Title of Invention	"CYLINDER INJECTION TYPE INTERNAL COBSUTION ENGINE"
Abstract	[Problem] To provide a cylinder injection-type internal combustion engine with superior starting performance with simple control. [Resolving Means] A cylinder injection type internal combustion engine has a fuel/air injection valve for directly injecting a fuel/air mixture of fuel and injection air into a combustion chamber, an air pump driven by the power of a crankshaft for discharging compressed air constituted by the injection air, and control means for setting injection timing of the fuel/air injection valve. When starting of the internal combustion engine is detected, the control means sets the injection timing TM to the intake stroke (S3, S12, S13), and when the engine rotational speed Ne reaches a prescribed engine rotational speed Nel corresponding to a state where the pressure of the injection air reaches a set pressure where injection of the fuel/air mixture is possible on the compression stroke, switches the injection timing TM from the intake stroke to the compression stroke (S3, S12, S14).

Title of Invention

"CYLINDER INJECTION TYPE INTERNAL COBSUTION ENGINE"

Abstract

[Problem] To provide a cylinder injection-type internal combustion engine with superior starting performance with simple control. [Resolving Means] A cylinder injection type internal combustion engine has a fuel/air injection valve for directly injecting a fuel/air mixture of fuel and injection air into a combustion chamber, an air pump driven by the power of a crankshaft for discharging compressed air constituted by the injection air, and control means for setting injection timing of the fuel/air injection valve. When starting of the internal combustion engine is detected, the control means sets the injection timing TM to the intake stroke (S3, S12, S13), and when the engine rotational speed Ne reaches a prescribed engine rotational speed Nel corresponding to a state where the pressure of the injection air reaches a set pressure where injection of the fuel/air mixture is possible on the compression stroke, switches the injection timing TM from the intake stroke to the compression stroke (S3, S12, S14).

Full Text	The present invention relates to a cylinder injection type internal combustion engine equipped with a fuel/air injection valve for directly injecting a fuel/injection air mixture into a combustion chamber, and particularly relates to a cylinder injection type internal combustion engine where discharged air is compressed air from an air pump driven by the power of a crank shaft of an internal combustion engine. [Related Art] Conventionally, that disclosed, for example, in patent document 1, is taken as this type of cylinder injection type internal combustion engine. This internal combustion engine is equipped with a fuel injection unit for injecting a fuel-air mixture of fuel and compressed air directly into a combustion chamber and a compressor driven by a crankshaft in order to provide compressed air to an air duct communicating with the fuel injection unit. Fuel supplied to the fuel injection unit is mixed with compressed air within the fuel injection unit and is injected into the combustion chamber from the air duct together with the compressed air. An internal combustion engine with good combustibility is therefore obtained because a powerful airflow is formed due to the injected compressed air so as to promote atomization of the fuel. However, at the time of starting up the internal combustion engine, and in particular, directly after the beginning of starting up, the amount of discharged gas for the compressor is small. Therefore, when the pressure of the compressed air within the air duct falls due to the internal combustion engine having been' stopped for a long time, it is not possible to provide compressed air of a pressure sufficient to convey the fuel to within the cylinder. Because of this, the air flow formed within the combustion chamber by the compressed air injected from the fuel injection unit is weak, it becomes difficult for the fuel to be atomized, combustibility falls, and starting performance is therefore lowered. The internal combustion engine of patent document 1 opens a valve of the fuel injection unit of a cylinder on a compression stroke at the time of starting up, and increases the air pressure within the air cylinder by guiding compressed air within the cylinder to within the fuel injection unit. [Patent Document 1] Japanese Patent Publication No. 2000-514150. [Problems To Be Solved By The Invention] However, in the related technology, compressed air at the time of the compression stroke bleeds via the fuel injection unit. The pressure within the cylinder therefore falls, and the starting performance of the internal combustion engine deteriorates. Further, it is necessary to control the timing of valve opening of the fuel injection unit in order to increase the air pressure within the air duct. Control of the fuel injection unit therefore becomes complex and cost is increased in cases where a pressure sensor is required to detect the pressure within the air duct. Moreover, as there is a small amount of oil mixed in with the air within the cylinder, this oil adheres to or accumulates on the walls of an air passage within the fuel injection unit as a deposit and hinders the flow of the compressed air. In order to resolve the aforementioned situation, it is the object of the invention as disclosed in claim 1 to claim 4 to provide a cylinder injection type internal combustion engine with superior starting performance using straightforward control. It is a further object of the invention of claims 2 and 3 to reduce costs and it is an object of claim 4 to improve fuel efficiency. Accordingly, there is provided a cylinder injection type internal combustion engine, having a fuel/air injection valve for directly injecting a fuel/air mixture of fuel and injection air into a combustion chamber, an air pump driven by the power of a crankshaft for discharging compressed air constituting the injection air, and control means for setting injection timing of the fuel/air injection valve, comprising : engine state detecting means for detecting an engine state of the internal combustion engine, wherein the control means sets the injection timing to the compression stroke of the internal combustion engine according to the engine state detected by the engine state detecting means characterized in that when starting up of the internal combustion engine is detected by the engine state detecting means, the infection timing is set to the intake stroke of the internal combustion engine and control during starting is executed. The cylinder injection type internal combustion engine, wherein the engine state detecting means comprises rotational speed detecting means for detecting rotational speed of the engine, so that when the pressure of the injection air is detected to have reached a prescribed engine rotating speed corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the rotational speed detecting means, during starting control, the control means switches over the injection timing from the intake stroke to the compression stroke. According to this, at the time of starting up the internal combustion engine, when the rotational speed of the engine falls so that the pressure of the injection air that is rising in pressure due the compressed air ejected from the air pump driven by the power of the crank shaft is not of a sufficiently high pressure to inject a fuel-air mixture on the compression stroke, the fuel-air mixture is injected from the fuel/air injection valve at the time of the intake stroke so that the pressure within the internal combustion engine becomes negative pressure. At this time, in addition to there being a negative pressure state within the combustion chamber, the injection air has a pressure that is higher than the relatively low pressure of atmospheric air as a result of the compressed air being supplied from the air pump and the difference in pressure between the pressure of the fuel air mixture within the fuel/air injection valve and the pressure within the combustion chamber is therefore large so as to promote atomizing of the fuel within the combustion chamber. A powerful airflow is therefore formed within the combustion chamber by high-pressure injection air injected together with the fuel from the fue]/air injection valve at the time of the compression stroke according to the engine state so as to promote atomizing of the fuel. Superior combustibility can therefore be attained and a stratified combustion operation is possible. As a result, according to the invention as disclosed in claim 1, the following results are obtained. Namely, in a cylinder injection type internal combustion engine where the injection timing to the combustion chamber of the fuel/air injection valve is set to the compression stroke according to the engine state, when starting of the internal combustion engine is detected, the injection timing is set to the intake stroke. It is therefore possible to promote atomizing of the fuel within the combustion chamber, improve combustibility during starting, and improve starting performance. Further, the air pressure at the time of the compression stroke is utilized in air injection and there is substantially no fear of the air path within the fuel/air injection valve becoming blocked up due to deposits. Further, by setting the injection timing of-the fuel/air injection valve to the compression stroke, superior combustibility is obtained, and stratified combustion is possible. In the invention as disclosed in claim 2, in the cylinder injection type internal combustion engine as disclosed in claim 1, the engine state detecting means comprises rotational speed detecting means for detecting rotational speed of the engine, so that when the pressure of the injection air is detected to have reached a prescribed engine rotating speed corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the rotational speed detecting means, during starting control, the control means swirches over the injection timing from the intake stroke to the compression stroke. [0012] According to this, when pressure of the injection air reaches a basic air pressure, the injection period is switched over from the intake stroke to the compression stroke based on detection results of the rotational speed detecting means and atomizing of the fuel is carried out using high-pressure injection air without having to use a pressure sensor for detecting pressure of the injection air. [0013] As a result, according to the claim 2 of the invention, in addition to the results of the invention disclosed in claim 1, the following results are attained. A pressure sensor is therefore not required to detect pressure of the injection air, costs can be reduced, and atomizing of fuel can be carried out using high-pressure injection air so as to ensure good starting performance. [0014] With the invention disclosed in claim 3, the cylinder injection type internal combustion engine disclosed in claim 1 is such that, the engine state detecting means comprises injection frequency detecting means for detecting injection frequency of the fuel/air injection valve, so that when the pressure of the injection air is detected to have reached a prescribed injection frequency corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the injection frequency detecting means, during starting control, the control means switches over the injection timing from the intake stroke to the compression stroke. [0015] According to this, when pressure of the injection air reaches a basic air pressure, the injection period is switched over from the intake stroke to the compression stroke based on detection results of the injection frequency detecting means after completion of control during starting and atomizing of the fuel is carried out using high-pressure injection air without having to use a pressure sensor for detecting pressure of the injection air. As a result, according to the claim 3 of the invention, the same results as for the invention of claim 2 are attained. [0016] Tn the invention as disclosed in claim 4, with the cylinder injection type internal combustion engine as disclosed in claim 1, the engine state detecting means comprises time detecting means for detecting a time of halting the internal combustion engine, so that when the halt time detected by the time detecting means is within a prescribed halt time corresponding to a state where pressure of the injection air is greater than a basic air pressure where injection of the air mixture is possible in the compression stroke when starting of the internal combustion engine is detected by the engine state detecting means, the control means sets the injection timing to the compression stroke, and when the halt time exceeds the prescribed halt time, control during starting is executed. [0017] According to this, because the halt time from the time of halting operation for the previous time for the internal combustion engine to the timing for starting the start up on this occasion is within a prescribed halt time, there is substantially very little or no drop in pressure of the injection air due to leaking of compressed air from between slight gaps existing in the air supply system etc. from the air pump to the fuel/air injection valve. When the pressure of the injection air is then greater than the basic air pressure at the starting timing, fuel/air mixture can be injected in the compression stroke without executing control during starting. A powerful airflow is therefore formed within the combustion chamber by injection air of a pressure greater than the basic air pressure and fuel atomizing is promoted. It is therefore possible to obtain superior combustibility and stratified combustion operation is possible directly after the start of starting-up. [0018] As a result, according to the claim 4 of the invention, in addition to the results of the invention disclosed in claim 1, the following results are attained. Namely, even when an internal combustion engine is in a start state, when the halt time of an internal combustion engine is within a prescribed halt time, it is possible to improve combustibility by carrying out injection of an air-fuel mixture using high-pressure injection air without carrying out control during starting, superior starting performance is ensured, and the start timing of a stratified combustion operation is made to come about more quickly, so that fuel consumption is dramatically improved. [0019] [Brief Description of the Drawings] FIG. 1 is a partial cross-sectional view of a plane orthogonal to a central line of rotation L2 of a crankshaft of a multi-cylinder injection-type internal combustion engine constituting an embodiment of the present invention, and is as viewed from I of FIG. 3 and FIG. 5. FIG. 2 is a cross-sectional view of a plane perpendicular to a central line of rotation of a crankshaft containing a cylinder axis line for a crankcase and cylinder of the internal combustion engine of FIG. 1, and is a cross-sectional view as viewed from II—II of FIG. 5 for a cylinder head. FIG. 3 is a cross-sectional view from III—III of FIG. 5. FIG. 4 is an enlarged view of essentia] parts of a cylinder head and head cover of FIG. 2, and is a cross-sectional view from IV-IV of FIG. 8 of the vicinity of an air pressure regulator. FIG. 5 is a view from V of FIG. 1 when the head cover is outside. FIG. 6 is a partial cross-sectional view mainly from VI-VI of FIG. 5 of essential parts. FIG. 7 is a schematic view illustrating a fuel supply system and air supply system for a fuel/air mixture valve of the internal combustion engine of FIG. 1. FIG. 8 is a view of the head cover from VIII of FIG. 1. FIG, 9 is a flowchart illustrating a routine for control during starting for injection timing of a fuel/air mixture valve of the internal combustion engine of FIG. 1. FIG. 10 is a schematic view illustrating injection timing for a fuel/air mixture valve and fuel injection valve of the internal combustion engine of FIG. 1, discharge timing of an air pump, and ignition timing, where FIG. 10(A) is a view for when the fuel/air injection valve injects a fuel/air mixture on the intake stroke, and FIG. 10(B) is a view when the fuel/air injection valve injects a fuel/air mixture on the compression stroke. FIG. 11 is a flowchart illustrating a routine for control during starting for injection timing of a fuel/air mixture valve of a multi-cylinder injection-type internal combustion engine constituting a further embodiment of the present invention. [Embodiments] In the following, a description is given of embodiments of the present invention with reference to FIG. 1 to FIG. 11. Referring to FIG. 1 to FIG. 3, an cylinder injection type internal combustion engine E to which the present invention is applied is a water-cooled single-cylinder four-stroke internal combustion engine mounted on a vehicle constituted by a motorcycle, and is equipped with an engine body comprised of a crankcase 1 forming a crank chamber housing a crankshaft 5, a cylinder 2 connected to an upper end of the crankcase 1, a cylinder head 3 coupled to the upper end of the cylinder 2, and a head cover 4 coupled to an upper end of the cylinder head 3. [0020] The internal combustion engine E is arranged so as to be laid so that the crankshaft 5 extends in a direction from left to right of the vehicle (vehicle width direction) so as to be suspended at the vehicle in a state where the cylinder 2 positioned to the front of the vehicle with respect to the crankshaft 5 is inclined slightly upwards with respect to the vehicle (refer to FIG. 1 and FIG. 2). [0021] In this embodiment, with regards to the body of the internal combustion engine E, in the direction D of a cylinder shaft line LI, an upward direction is the direction where the cylinder head 3 is positioned with respect to the cylinder 2. [0022] A piston 6 fitted so as to be reciprocally moveable at a cylinder hole 2a of the cylinder 2 is coupled to the crankshaft 5 supported in a rotatable manner at the crankcase 1 via a connecting rod 7. A combustion chamber 8 constituted of a recess 3a formed at the lower surface of the cylinder head 3 and a cavity 6a formed at the top surface of the piston 6, between the piston 6 and the cylinder head 3. [0023] Referring to FIG. 4, an intake port 9 having a pair of intake openings 9a opening at the combustion chamber 8 and an exhaust port 10 having a single exhaust opening 10a opening at the combustion chamber 8 are formed at the cylinder head 3 and are provided with a pair of intake valves 11 opening and closing the pair of intake openings 9a and a single exhaust valve 12 opening and closing the exhaust opening 10a. A fuel/air injection valve 30 and sparkplug 14 are fitted facing the combustion chamber 8. [0024] The fuel/air injection valve 30 is arranged at a substantially central part of the combustion chamber 8 as viewed from a cylinder axis line direction D so as to have an axial line of substantially the same axis as that of the cylinder shaft line LI so as to directly inject a fuel-air mixture of fuel and compressed air into the combustion chamber 8. Both of the intake valves 11, the exhaust valve 12 and the sparkplug 14 are arranged spaced apart in a circumferential direction about the periphery of the fuel/air injection valve 30 taking the fuel/air injection valve 30 as center. [0025] An intake pipe 15 of an intake device having an air cleaner 51 (refer to FIG. 7) and a throttle body is connected so as to communicate with an inlet 9b at a side surface of the intake side of the cylinder head 3 at which the inlet 9b of the intake port 9 opens, and an exhaust pipe of an exhaust device is connected to the side surface of an exhaust side of the cylinder head 3 at which an outlet 10b of the exhaust port 10 opens. [0026] Here, intake side refers to the side where the intake port 9 is positioned with respect to a plane H parallel with a rotation center line L2 of the crankshaft 5 containing the cylinder shaft line LI at the engine body, and exhaust side refers to the side where the exhaust port 10 is positioned with respect to plane H at the engine body. [0027] Intake air provided from the intake device via the intake pipe 15 is drawn into the combustion chamber 8 via the pair of opened intake valves 11 from the intake ports 9 when the piston is on the downward intake stroke. Fuel injected into the combustion chamber 8 from the fuel/air injection valve 30 in a state mixed with air is combusted by a spark from the sparkplug 14 after being compressed by the rising piston 6 on the compression stroke, and the piston 6 falling due to the pressure of the combusted gas on the expansion stroke rotates the crankshaft 5 via the connecting rod 7. On the exhaust stroke, the combusted gas is exhausted from the combustion chamber 8 to the exhaust port 10 as exhaust gas via the open exhaust valve 12 and is further exhausted to the outside via the exhaust device. [0028] Referring to FIG. 1 to FIG. 5, a valve assembly 16 for opening and closing the intake valves 11 and the exhaust valve 12 is comprised of a cam shaft 17 an intake cam 18i and an exhaust cam 18e supported in a rotatable manner at side parts of the cylinder 2, an intake cam follower 20i making contact with the intake cam 18i and an exhaust cam follower 20e making contact with the exhaust cam 18e respectively supported in a swingable manner at a pair of support shafts 19i, 19e supported at the cylinder 2, intake rocker arms 22i making contact with tips of valve stems of the pair of intake valves 11 and an exhaust rocker arm 22e making contact with the tip of a valve stem of the exhaust valve 12 supported respectively in a swingable manner at a pair of rocker shafts 21i, 21e supported at the cylinder head 3, and a pair of rods 23i, 23e, making contact with the ends of the cam follower 20i and exhaust cam follower 20e and the intake rocker arm 22i and exhaust rocker arm 22e, and transmitting the rocking action of the cam follower 20i and the exhaust cam follower 20e to the intake rocker arm 22i and exhaust rocker arm 22e. [0029] As shown in FIG. 1, the cam shaft 17 is rotatably driven at a rotational speed that is half the rotational speed of the cam shaft 17 by driving force of a crankshaft 5 transmitted via a transmission mechanism containing a drive sprocket 24 provided at the crankshaft 5, a cam sprocket 25 provided at cam shaft 17 and a timing chain 26 spanning the sprockets 24 and 25. The intake cam 18i and the exhaust cam 18e rotating together with the cam shaft 17 open and close the pair of intake valves 11 and the exhaust valve 12 urged in a valve-closing direction by a valve spring 27 at prescribed opening and closing timings in synchronization with rotation of the crankshaft 5 via the intake cam follower 20i and the exhaust cam follower 20e, a pair of rods 23i, 23e, the intake rocker arms 22i, and the exhaust rocker arm 22e. [0030] Referring to FIG. 3 and FIG. 6, the fuel/air injection valve 30 fitted so as to extend at the cylinder head 3 and the head cover 4 directly injects a fuel/air mixture formed of fuel and injection air into the cavity 6a of the combustion chamber 8. [0031] The fuel/air injection valve 30 is comprised of a fuel injection valve 31, inserted into an insertion tube 4c formed at the head cover 4, for injecting fuel provided via a fuel supply system 40 (refer to FIG. 7), and an air injection valve 32, inserted into an insertion tube 3c formed at the cylinder head 3, for injecting a fuel/air mixture of fuel injected from the fuel injection valve 31 and injection air provided via an air supply system 50 (refer to FIG. 7) from a nozzle 32a having a valve body 32al opening and closing a nozzle hole (not shown) to within the combustion chamber 8. [0032] An annular fuel chamber 36 sealed by a pair of annular seals 33, 34 fitted about the outer periphery of a valve body 31b of the fuel injection valve 31 is formed so as to encompass the valve body 31b. Fuel is supplied to the fuel chamber 36 from the fuel supply system 40. An annular air chamber 37 sealed by a seal 34 and an annular seal 35 fitted about the outer periphery of the valve body 32b of the air injection valve 32 is formed so as to encompass a nozzle section 31a of the fuel injection valve 31 and an air introducing section 32c of the air injection valve 32 between the insertion tube 4c, fuel injection valve 31 and air injection valve 32. Compressed air from the air supply system 50 is supplied as injection air at the air chamber 37. [0033] The amount of fuel contained in the fuel/air mixture injected from the fuel/air injection valve 30, injection timing TM (refer to FIG. 10) of the fuel/air injection valve 30 and the injection amount are set by electronic control means (hereinafter referred to as "ECU") 80 (refer to FIG. 1) taken as control means according to engine conditions such as engine load of the internal combustion engine E, engine rotational speed Ne, and engine temperature etc. detected by engine state detecting means described later. Further, spark timing Ti (refer to FIG. 10) of the sparkplug 14 is also controlled by the ECU 80 according to the engine states. [0034] The fuel injection valve 31 and the air injection valve 32 are comprised of a solenoid valve driven to open and close by a signal from the ECU 80. The fuel injection valve 31 injects fuel flowing from the fuel chamber 36 through a fuel introduction opening 31c formed in the valve body 31b from the nozzle section 31a through the air introducing section 32c and into the valve body 32b of the air injection valve 32 at an injection timing TF (refer to FIG. 10) and fuel amount set by the ECU 80 according to the engine states. After this, the air injection valve 32 injects a fuel/air mixture of fuel within the valve body 32b and injection air within the valve body 32b and of the air chamber 37 from the facing nozzle section 32a within the combustion chamber 8 towards the cavity 6a at an injection timing and injection amount that is the injection timing TM and the injection amount of the fuel/air injection valve 30. [0035] Referring to FIG. 7, the fuel supply system 40 is comprised of an electric-powered fuel pump 42 for force-feeding liquid fuel pumped from a fuel tank 41 at high-pressure, a fuel pressure regulator 43 for regulating pressure of fuel supplied from the fuel pump 42 to the fuel chamber 36 to a set fuel pressure PF, and a fuel passage system 44 communicating with the fuel pump 42, fuel pressure regulator 43 and fuel chamber 36. Referring to FIG. 6 and FIG. 8, fuel at the set fuel pressure PF is supplied to the fuel chamber 36 via a fuel passage 44c comprised of holes formed in the head cover 4 via a fitting 46 to which a pipe 45 is connected. Fuel passages 44a, 44b and a fuel passage 44c formed respectively by the pipe 45 and the fitting 46 constitute part of the fuel passage system 44. Surplus fuel of the fuel discharged from the fuel pump 42 is returned to the fuel tank 41 from the fuel pressure regulator 43 via a return fuel passage 47. [0036] Referring to FIG. 5 to FIG. 7, the air supply system 50 is comprised of an air pump 52 discharging air drawn in from an air cleaner 51 of the intake device driven by the power of the crankshaft 5, an air pressure regulator 53 for regulating the pressure of the injection air constituted by the compressed air discharged from the air pump 52 supplied to within the air chamber 37 to a set air pressure PA, and an air passage system 54 communicating with the air pump 52, air pressure regulator 53, and air chamber 37. The set air pressure PA is a pressure capable of enabling injection of a fuel/air mixture from the fuel/air injection valve 30 in the compression stroke and preferably in the latter half of the compression stroke, and is set to be a pressure that is as low as possible to enable injection of the fuel/air mixture in the compression stroke while being higher than a basic air pressure PAO. [0037] The air pump 52 provided at the exhaust side of the cylinder 2 is a displacement-type reciprocal-type pump for discharging compressed air of a pressure higher than the set air pressure PA at a discharge timing TA described later and is comprised of a pump body 52a formed integrally with the cylinder 2, a pump cover 52b coupled via a gasket 52c constituted by a thin plate at the pump body 52a, a rotating shaft 55 rotatably drive by the force of the crankshaft 5 supported in a rotatable manner at the cylinder 2, and a piston 52d coupled to the rotating shaft 55 forming a pump chamber 52e with a pump cover 52b inserted in a manner capable of reciprocal movement at the pump body 52a. [0038] An intake section formed from an intake path 52fl provided with an intake valve comprised of a reed valve taking part of a gasket 52c as a reed body and a discharge section 52g formed with a discharge path 52gl provided with a discharge valve 52h having a valve body 52hl urged by a spring 52h2 are formed at the pump cover 52b. Referring to FIG. 1 and FIG. 3, the rotating shaft 55 is rotatably driven at the same speed as the cam shaft 17 by power of the crankshaft 5 transmitted via a transmission mechanism comprised of a drive sprocket 56 provided at the crankshaft 5, a driven sprocket 57 provided at the rotating shaft 55 and a transmission chain 58 spanning the sprockets 56, 57. [0039] The pump cover 52b and the discharge section 52g are as a whole arranged next to the exhaust side of the cylinder head 3, are positioned to the side of the cylinder head 3 from a joining surface 3d, and the uppermost end of the pump chamber 52e is positioned substantially above the joining surface 3d. Further, the whole of the air chamber 37 is positioned more towards the air pump 52 than the fuel chamber 36. [0040] The piston 52d is coupled to the rotating shaft 55 via a Scotch yoke mechanism. Specifically, the piston 52d is coupled via a sliding piece 59 fitting in a sliding manner into a columnar guide hole formed at the piston 52d to an eccentric shaft 55a provided eccentrically from a centerline of rotation of the rotating shaft 55 at one end of the rotating shaft 55, so as to be made to move in a reciprocal manner in an axial direction of the pump body 52a within the pump body 52a due to rotation of the rotating shaft 55. A transmission mechanism for rotatably driving an impeller of a cooling water pump 28 is provided at the other end of the rotating shaft 55. [0041] Air drawn into the pump chamber 52e from the intake path 52fl via the a fitting 60 to which a pipe communicating with the air cleaner 51 is connected is compressed to a high pressure by the piston 52d, the discharge valve 52h is opened, and the air is discharged at the discharge path 52gl as compressed air. [0042] Referring to FIG. 4 and FIG. 8, the air pressure regulator 53 is fitted to the head cover 4 so as to be partially contained in a storage section 4d integrally formed at an intake side of the head cover 4. The air pressure regulator 53 is comprised of a first case 53a contained in a storage chamber 4e formed at the storage section 4d and a second case 53b positioned at an outside part of the storage chamber 4e so as to be covered by a cover 53c. An air introduction chamber 63 sealed by a pair of annular seals 61, 62 fitted to the first case 53a so as to encompass the first case 53a between the seals 61 and 62 and a return air chamber 64 encompassing an air discharge section 53al of the first case 53a between the seal 62 and the bottom of the storage section 4d are formed between the storage section 4d and the first case 53a. At the return air chamber 64, surplus air discharged from the air pressure regulator 53 during pressure regulation is guided along the air discharge section 53a 1. [0043] An air guide hole 53d for guiding outside air as fluid having standard pressure during correction of the set air pressure PA is formed at the second case 53b. The outside air flows from a gap 53e formed between the storage section 4d and the cover 53c into a gap 53f formed between the second case 53b and the cover 53c so as to flow into the air pressure regulator 53 from the air guide hole 53d opened in the gap 53f. [0044] Referring to FIG. 7, the air introduction chamber 63 guides air having the set air pressure PA taken as a fluid having a reference pressure during correction of the set fuel pressure PF of the fuel pressure regulator 43 according to the pressure within the air chamber 37 so that the air communicates with the fuel pressure regulator 43 via an air passage partially constituted by a passage 65a formed at the storage section 4d. Further, the return air chamber 64 communicates with the air cleaner 51 via a return air path 67 formed from a fitting 66 fitted to the storage section 4d and piping (not shown) connected to the fitting 66, etc. Surplus air of compressed air discharged from the air pump 52 is circulated back to the air cleaner 51 from the air pressure regulator 53 via the return air path 67. [0045] Referring to FIG. 5 to FIG. 8, the air passage system 54 is comprised of an air passage 54a formed by a pipe 68 connected to an outlet of the discharge path 52gl of the pump cover 52b, a head-side air passage 54b comprised of a hole formed in the cylinder head 3, a cover-side air passage 54c comprised of a hole formed in the head cover 4, a connection air passage 54d formed from a hollow positioning pin 69 provided at the surface where the cylinder head 3 and the head cover 4 join in order to connect the head-side air passage 54b and the cover-side air passage 54c, and a branching air passage 54e branching from the cover-side air passage 54c. [0046] The branching air passage 54e comprised of a hole formed in the head cover 4 communicates with the air chamber 37 and the air pressure regulator 53 via the cover-side air passage 54c. An orifice 70 (refer also to FIG. 4) is provided at the branching air passage 54e. By using this orifice 70, the pressure of the injection air within the air chamber 37 can be kept higher than the set air pressure PA at the timing of emission of compressed air of a pressure higher than that of the set air pressure PA from the air pump 52 at a prescribed time from the emission start timing of the air pump 52. The orifice 70 therefore constitutes a high-pressure maintaining structure for temporarily keeping the injection air pressure at a higher pressure than that of the set air pressure PA at least until a timing coinciding with the injection start timing of the fuel/air injection valve 30. Further, pulsing of the compressed air guided by the air pressure regulator 53 is suppressed by the orifice 70 and the precision of the regulating function of the air pressure regulator 53 is improved. [0047] Further, by arranging the pipe 68 on the exhaust side of the cylinder 2 and forming the head-side air passage 54b and the cover-side air passage 54c on the exhaust side of the cylinder head 3 and the exhaust side of the head cover 4 respectively, of the air passage system 54, the air passages 54a, 54b and 54c reaching the air chamber 37 from the air pump 52 can be provided on the exhaust side of the cylinder head 3 and the exhaust side of the head cover 4 for which the temperature is high compared with the intake side because of exhaust gas flowing through the exhaust port 10. [0048] Next, a description is given of control of the fuel/air injection valve 30 using the discharge timing TA of compressed air from the air pump 52and the ECU 80 with reference to FIG. 1, FIG. 3, FIG. 9 and FIG. 10. Referring to FIG. 1, detection signals from engine state detecting means comprised of a rotational speed sensor 81 for detecting rotation speed of the crankshaft 5 constituting rotational speed detecting means for detecting rotational speed Ne of the internal combustion engine E, a load sensor 82 for detecting opening of a throttle valve provided at the intake device constituting load detecting means for detecting engine load, a top dead center sensor 83 for detecting rotational position of the rotating shaft 55 constituting top dead center detecting means for detecting top dead center of a compression stroke of the internal combustion engine E, a starting sensor 84 constituting starting detecting means for detecting when the internal combustion engine E is in a starting state, a circulating water temperature sensor 85 constituting engine temperature detecting means for detecting engine temperature, an ignition switch 86 for putting an ignition circuit for controlling energizing of the sparkplug 14 in an operating state or a non-operating state, and a switch 87 for putting the ignition circuit in an operating state or non-operating state constituting idling stop detection means for detecting operation or non-operation of the idling stop control device based on a signal from the idling stop control device for putting the internal combustion engine E in a halted state at times of temporary stopping such as at an intersection etc. are inputted to the ECU 80. [0049] Here, the starting state of the internal combustion engine E is an operating state from a starting timing where a starting motor (not shown) taken as starting means is made to operate by a starting switch being put in an on state so that the crankshaft 5 currently in a stationary state starts to rotate to a starting completion timing where the internal combustion engine E is in a purely combustive state. In this embodiment, the starting sensor 84 is configured so as to utilize a rotational speed sensor 81, with the starting state taken to be when the engine rotational speed Ne is within the range of rotational speed from zero for a starting commencement timing to the engine rotational speed Ne at the timing where starting is complete. [0050] Further, control programs for controlling injection timing TF of injection of fuel injected from the fuel injection valve 31 and the amount of fuel (here, this is equivalent to the valve opening time) and controlling the injection timing TM and injection amount (which in this case is equivalent to the valve opening time) of injection timing TM and injection amount of the fuel/air mixture injected from the air injection valve 32, i. e. from the fuel/air injection valve 30 and various maps, with the ECU 80 controlling the fuel/air injection valve 30 in accordance with these control programs. [0051] In the following, a description is given with reference to FIG. 3, FIG. 9 and FIG. 10 of control of the fuel/air injection valve 30 at the time of the starting state of the internal combustion engine E. Referring to the flowchart of FIG. 9 for illustrating the control routine for the time of starting of the fuel/air injection valve 30, in step SI, a halt time determination flag Ft is set to 1 at the time of starting up this routine in order to carry out a determination in a step S6 once. [0052] Next, in step S2, a determination is made as to whether or not the ignition circuit is in an operating state, i.e. as to whether or not the ignition switch 86 and the switch 87 are both on, and when this determination is negative the routine is ended. When the switch 87 is on, the idling stop control device is in an non-operating state and an idling stop is not carried out. When the switch 87 is in an off state, the ignition circuit is in a non-operating state and the idling stop control device is in an operating state, so that idling stopping is carried out. When the determination of step S2 is affirmative, the rotational speed Ne of the engine detected by the rotational speed sensor 81 is read-in in step S3. Before commencement of starting, the engine rotational speed Ne is zero. [0053] Proceeding to step S4, a determination is made as to whether or not the internal combustion engine E is in a starting state based on a detection signal from the starting sensor 84. When this determination is negative, the internal combustion engine is operating in a state other than a starting state. Step S15 is then proceeded to and a determination is made as to whether or not the ignition circuit is in a non-operating state due to the ignition switch 86 and the switch 87 being in off states. When this determination is negative, the internal combustion engine E is in an operating state, step S3 is returned to and execution of the processing of this routine continues to be executed. [0054] When the determination of step S4 is affirmative, when the internal combustion engine E is in the starting state, step S5 is proceeded to and flag Ft is referred to. When flag Ft is set to 1 so that it is necessary to determine whether or not the stop time t is within a prescribed stop time tl, step S6 is proceeded to. When the determination of step S5 is negative, determination of the stop time t has already been executed. Step Sll is then proceeded to and a determination is then made as to whether or not control during starting of the injection timing TM (refer to FIG> 10) of the fuel/air injection valve 30 is to be carried out. [0055] In step S6, a determination is made as to whether or not stop time t detected by a timer constituting time detecting means for detecting the stop time of the internal combustion engine E from the stop timing of the previous time to the starting commencement timing of this time is within a prescribed stop time tl corresponding to the state where the pressure of the injection air is greater than the basic air pressure PA0. This timer is also constituted by the engine state detecting means for detecting engine states of the internal engine E. [0056] The pressure of the injection air gradually falls as the stop time t elapses due to leaking of compressed air from slight gaps in the air supply system 50 formed of the cylinder 2, cylinder head 3, and head cover 4 etc. due to the operation of the air pump having stopped at the time of stopping the internal combustion engine E. The basic air pressure PA0 is the lowest possible pressure capable of enabling injection of the fuel/air mixture from the fuel/air injection valve 30 on the compression stroke. [0057] Therefore with normal temporary stopping of the internal combustion engine E and idling stops etc., at the time of a restarting operation within a short time after stopping the internal combustion engine E, the stop time t is comparatively short. The fall in pressure of the injection air is therefore substantially non-existent or small, and the pressure of the injection air is a value greater than the basic air pressure PAO. Because of this, after a stop time that is a short time such as for an idling stop, when the internal combustion engine E is re-started, the determination in step S6 is affirmative, and step S8 is proceeded to after the flag Ft is set to zero in step S7. In step S8, the injection air is of a pressure greater than the basic air pressure PAO and injection of the fuel/air mixture in the compression stroke is possible and it is therefore not necessary to inject the fuel/air mixture on the intake stroke. A starting time control flag Fs can then be set to zero in order to indicate that control during starting of the injection timing TM is not executed. [0058] As the stop time t is long, time corresponding to the state where the pressure of the injection air is lower than the basic air pressure PAO elapses. Therefore, when the determination of step S6 is negative, in step S9, the flag Ft is set to zero, and step S10 is proceeded to. In step S10, the injection air is at a pressure lower than the basic air pressure PAO and injection of the fuel/air mixture at the time of the compression stroke is difficult. Flag Fs is then set to 1 in order to indicate that control during starting is executed to set the injection timing TM at the intake stroke, and step Sll is proceeded to. [0059] Then, in step Sll, when the flag Fs is 1, step S12 is proceeded to and a determination is made as to whether or not the engine rotational speed Ne has reached a prescribed engine rotation speed Nel. This prescribed engine rotational speed Nel is the engine rotational speed Ne corresponding to when the pressure of the injection air within the air chamber 37 reaches the basic pressure PAO and is set in advanced based on experimentation etc. [0060] When the determination of step S12 is negative, i.e. when it is determined that the pressure of the injection air within the air chamber 37 has not reached the basic air pressure PAO, step S13 is proceeded to, and the injection timing TM of the fuel/air injection valve 30 is only set for the intake stroke. As shown in FIG. 10(A), in advance of the injection timing TM, fuel injected at an injection timing TF from the fuel injection valve 31 is injected in the direction of the combustion chamber 8 which is at negative pressure due to being at an intake stroke together with the injection air one time every cycle of the internal combustion engine E. As a result of the injection of the fuel/air mixture on this intake stroke, a substantially homogenous fuel/air mixture is formed within the whole of the combustion chamber 8 up to the ignition timing Ti prior to the compression top dead center point, and this homogenous fuel/air mixture can then be combusted in a homogenous manner. [0061] More specifically, when one cycle is carried out in the order of an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke, at each cycle, the injection timing TF of the fuel injection valve 31 is set to the first half of the exhaust stroke, and the injection timing TM (the injection timing of the air injection valve 32) of the fuel/air injection valve 30 is set to be a timing that is slower than the injection timing TF and is set here to the first half of the intake stroke. [0062] At this time, when a long period of time has elapsed from the internal combustion engine E being stopped to the extent that the air pressure within the air chamber 37 becomes equal to the atmospheric pressure of the outside air due to leaking of compressed air from slight gaps in the air supply system 50, at the injection timing TF on the current cycle shown in FIG. 10(A), fuel injected from the fuel injection valve 31 is injected into the combustion chamber 8 together with the injection air having an increased air pressure for the previous cycle and injection air having air pressure equal to the atmospheric pressure at the time of the initial cycle after the current cycle commences starting. At the cycle for this time, compressed air discharged at the discharge timing TA of the air pump 52 set to span from the first half of the compression stroke to the second half is such that the pressure of the injection air within the air chamber 37 is raised, and the raised injection air is injected into the combustion chamber 8 together with the fuel on the next cycle. In the case where time that elapses from when the internal combustion engine E is stopped is not to the extent that the air pressure within the air chamber 37 becomes equal to the atmospheric pressure, the fuel/air mixture is injected using injection air of a pressure higher than the atmospheric pressure from commencement of starting. [0063] As a result of using the series of steps of step S4 to S6, and S9 to S13, when the air pressure of the injection air becomes lower than the basic air pressure PA0 and the internal combustion engine E then commences starting with the stop state having spanned a length of time sufficient, for example, for the air pressure of the injection air to become equal to the atmospheric air pressure, the compression timing TM can always be set to the intake stroke. [0064] When the determination of step S12 is affirmative, the injection air pressure is greater than the basic air pressure PAO. Step S14 is then proceeded to, and the injection timing TM of the fuel/air injection valve 30 is switched over from the intake stroke to the compression stroke, and set to the compression stroke. As shown in FIG. 10(B), in advance of the injection timing TM, fuel injected at an injection timing TF from the fuel injection valve 31 is injected in the direction of the combustion chamber 8 which is at negative pressure due to being at an intake stroke together with the injection air one time every cycle of the internal combustion engine E. At this time, fuel/air mixture injected from the fuel/air injection valve 30 mostly collects within the cavity 6a, and in order to prevent or suppress dispersion at the combustion chamber 8, stratified combustion is carried out so as to combust the fuel/air mixture with a fuel/air mixture of good combustibility existing in the vicinity of the sparkplug 14 with an air layer that does not include fuel being present at the periphery of the cavity 6a. [0065] More specifically, at each cycle, discharge timing TF of the fuel injection valve 31 is set to a higher timing than the discharge timing TA of, for example, the latter half of the intake stroke, with respect to the discharge timing TA of the air pump 52 set spanning from the former half of the compression stroke to the latter half. The discharge timing TM of the fuel/air injection valve 30 (also the discharge timing of the air injection valve 32) is a timing partially overlapping with the discharge period TA, does not overlap with the discharge timing TA, and is set to the latter half of the compression stroke at a timing that is slightly slower than the discharge timing TA. In either case, the injection timing TM is set to overlap with a timing period such that the pressure of injection air within the air chamber 37 is held at a state higher than the set air pressure PA. [0066] In the starting state, the engine state from the commencement of starting until a prescribed engine rotational speed Nel is reached is a first engine state corresponding to a state where the pressure of the injection air is less than the basic air pressure PAO. At the time of this first state, the injection timing TM of the fuel/air injection valve 30 is set to the intake stroke. In the starting state, the engine state when the prescribed engine rotational speed is Nel or more is a second engine state corresponding to a state where the pressure of the injection air is the basic air pressure PA () or more. At the time of this second state, the injection timing TM of the fuel/air injection valve 30 is set to the compression stroke. [0067] In relation to step S4, when the internal combustion engine E operates in a state other than at the time of starting, the injection period TM is set at the compression stroke or the intake stroke according to the engine state by the ECU 80. For example, directly after completion of starting of the internal combustion engine E, the injection timing TM of the fuel/air injection valve 30 is set to the latter half of the compression stroke as shown in FIG. 10(B) in a partial running region of the internal combustion engine E such as during idling and low-speed or low-load running, and stratified combustion is carried out. Further, in a separate running region of the internal combustion engine E for the time of high-speed or high-load running of the internal combustion engine E etc., the injection timing TM of the fuel/air injection valve 30 is set to the intake stroke, a substantially homogeneous fuel/air mixture is formed in the whole of the combustion chamber 8, and uniform combustion is carried out. [0068] When the determination of step S4 is negative and the determination of step S15 is affirmative, then running of the internal combustion engine E has stopped, with this including idling stops. At this time, step S16 is proceeded to, and after the timer is reset, a count is started, and this routine ends. Then, the processing from step S3 to step S14 is executed every prescribed period by the ECU 80 until the determination of step S4 is negative due to starting being complete. [0069] The following is a description of the operation and effects of the embodiment with the configuration described above. In an internal combustion engine E equipped with the air pump 52 driven by the power of the fuel/air injection valve 30 and the crankshaft 5 and an ECU 80 for setting the injection timing TM of the fuel/air injection valve 30 to the intake stroke or the compression stroke according to the engine state detected by the engine state detecting means, when starting of the internal combustion engine E is detected by the starting sensor 84, the ECU 80 executes control at the time of starting for setting the injection timing TM to the intake stroke so that at the time of starting the internal combustion engine E, a fuel/air mixture is injected from the fuel/air injection valve 30 at the time of the intake stroke where the pressure within the combustion chamber 8 when the speed of the engine Ne becomes low so that the pressure of the injection air raised in pressure by compressed air discharged from the air pump 52 driven by the power of the crankshaft 5 is not of sufficiently high pressure to inject the fuel/air mixture on the compression stroke. At this time, in addition to there being a negative pressure state within the combustion chamber 8, the injection air has a pressure that is higher than the relatively low pressure of atmospheric air as a result of the compressed air being supplied from the air pump 52 and the difference in pressure between the pressure of the fuel air mixture within the fuel/air injection valve 30 and the pressure within the combustion chamber 8 is therefore large so as to promote atomizing of the fuel within the combustion chamber 8. A powerful airflow is therefore formed within the combustion chamber 8 by high-pressure injection air injected together with the fuel from the fuel/air injection valve 30 at the time of the compression stroke so as to promote atomizing of the fuel. Superior combustibility can therefore be attained and a stratified combustion operation is possible. [0070] As a result, atomizing of the fuel within the combustion chamber 8 is promoted, combustibility during starting is improved, and starting performance is also improved using simple control where the injection timing TM is changed to the intake stroke when starting of the internal combustion engine E is detected. Further, the air pressure within cylinder hole 2a at the time of the compression stroke is utilized in air injection and there is substantially no fear of the air path within the fuel/air injection valve 30 becoming blocked up due to deposits. Further, by setting the injection timing TM of the fuel/air injection valve 30 to the compression stroke, superior combustibility is obtained, and stratified combustion is possible. [0071] When a prescribed engine rotational speed Nel corresponding to the pressure of injection air reaching a basic pressure PA0 where injection of the fuel/air mixture in the compression stroke is possible is detected by the rotational speed sensor 81 constituting the engine state detecting means used for calculating fuel amount of the fuel/air injection valve 30 and injection timing period, the injection timing TM is switched over from the intake stroke to the compression stroke when the pressure of the injection air reached the basic air pressure PA0 based on detection results of the rotational speed sensor 81 without using a pressure sensor to detect pressure of the injected air and fuel atomizing is carried out using injection air of a pressure in excess of the basic air pressure PA0. [0072] A pressure sensor is therefore not required to detect pressure of the injection air, costs can be reduced, and atomizing of fuel can be carried out using high-pressure injection air so as to ensure good starting performance. [0073] When the halt time detected by the timer when starting of the internal combustion engine E is detected is within a prescribed halt time tl corresponding to a state where the injection air pressure is greater than the basic air pressure PAO, the ECU 80 sets the injection timing TM to the compression stroke. When the halt time t exceeds the prescribed halt time tl, as a result of execution of control at the time of starting, the halt time t from the running halt timing for the previous time of the internal combustion engine E to the running start period for this time is within the prescribed halt time t. Fall in pressure of injection air due to leaking of compressed air from minute gaps in the air supply system 50 and air chamber 37 from the air pump 52 to the fuel/air injection valve 30 is almost non-existent or small. The fuel/air mixture can therefore be injected on the compression stroke when the pressure of the injection air at the commencement of starting timing is greater than the basic air pressure PAO without executing control at the time of starting. A powerful airflow is therefore formed within the combustion chamber 8 by injection air of a pressure greater than the basic air pressure PAO and fuel atomizing is promoted. It is therefore possible to obtain superior combustibility and stratified combustion operation is possible directly after the start of starting-up. [0074] As a result, even when the internal combustion engine E is in a starting state, when activation of starting is within a short time after temporary halting such as an idling stop, i. e. when the halt time t is within the prescribed halt time tl, injection of a fuel/air mixture is carried out using high-pressure injection air without exerting control at the time of starting and combustibility is improved. Superior starting performance is therefore ensured, and the starting period for running in stratified combustion can be made faster so as to dramatically improve combustion. [0075] The discharge section 52g and pipe 68 of the air pump 52 are arranged next to the exhaust side of the cylinder head 3, and the head-side air passage 54b and cover-side air passage 54c are arranged at the exhaust side of the cylinder head 3 and at the exhaust side of the head cover 4 respectively. As a result, the air passages 54a, 54b, and 54c of the air passage system 54 guiding compressed air discharged from the air pump 52 are arranged at the exhaust side of the cylinder head 3 and the exhaust side of the head cover 4 which are at a comparatively high temperature compared to the intake side for exhaust gas flowing into the exhaust port 10. When compressed air that is compressed by the air pump 52 so as to rise in temperature flows through the air passages 54a, 54b and 54c, falls in the temperature of the compressed air are suppressed, and it is possible to maintain the temperature of the compressed air. [0076] As a result, when compressed air flows through the air passage system 54, the occurrence of condensation due to contact with passage walls that are at a lower temperature than the temperature of the compressed air is prevented or suppressed, and the temperature of the injection air within the air chamber 37 can be kept relatively high. The vaporization of fuel at the time of starting is therefore promoted and starting performance is also improved in this respect. [0077] The whole of the pump cover 52b and the discharge section 52g is positioned further to the side of the connecting surface 3d of the cylinder 2 of the cylinder 3, the uppermost part of the pump chamber 52e is positioned substantially above the connecting surface 3d, and the whole of the air chamber 37 is positioned further towards the air pump 52 than the fuel chamber 36. As a result, the air passages 54a, 54b and 54c reaching the air chamber 37 from the discharge section 52g of the air passage system 54 can be made small and can be arranged collectively at and close to the exhaust side of the cylinder head 3 where the exhaust port 10 is formed. The effect of retaining heat in the compressed air at the air passages 54a, 54b and 54c reaching the air chamber 37 from the air pump 52 of the air passage system 54 can therefore be improved. As a result, this contributes to keeping the temperature of the injection air comparatively high, vaporizing of fuel during starting is promoted, and starting performance is improved. [0078] By providing an orifice 70 constituting a high-pressure maintaining structure for temporarily keeping the pressure of the injection air at a pressure higher than the set air pressure PA at least until where timing overlaps with the injection start timing of the fuel/air injection valve 30 at the air passage system 54, fuel is injected together with injection air of a pressure higher than the set pressure PA at the injection timing TM and atomizing of fuel within the combustion chamber 8 is therefore promoted. [0079] As a result, when the discharge timing TM during starting is set to the compression stroke, atomizing of fuel within the combustion chamber is further promoted, and the starting performance is improved accordingly. [0080] Following is a description of the embodiment with a modified configuration of part of the configuration of the embodiment mentioned above. In the above embodiment, the timing of switching the injection timing TM from the intake stroke to the compression stroke is decided based on the engine rotational speed Ne. However, as shown in FIG. 11, this may also be decided based on an injection number Ni of the fuel/air injection valve 30 rather than on the engine rotational speed Ne. [0081] In a flowchart showing a control routine for control during starting of FIG. 11, processing of step S3 and step S12 of the flowchart of FIG. 9 are replaced with a process of step S23 and step S32, with other aspects of the processing being the same as for the flowchart of FIG. 9. [0082] Specifically, in step S23, a count for an injection frequency Ni of the fuel/air injection valve 30 is started from when the ignition circuit enters an operating state. In step S32, a determination is made as to whether or not Ni is less than or equal to a prescribed injection number Nil. The prescribed injection frequency Nil is the frequency of injection Ni corresponding to when the pressure of the injection air within the air chamber 37 reaches the basic pressure PA0 and may be a plurality of prescribed numbers such as, for example, 4 to 10, set in advance based on experimentation etc. [0083] When the determination of step S32 is negative, i.e. when it is determined that the pressure of the injection air has not reached the basic air pressure PA0, step S13 is proceeded to, and the injection timing TM of the fuel/air injection valve 30 is only set for the intake stroke. Further, when the determination of step S12 is affirmative, the pressure of the injection air is the basic pressure PA0 or more that is capable of injection of the fuel/air mixture on the compression stroke. Step S14 is then proceeded to, and the injection timing TM of the fuel/air injection valve 30 is switched over from the intake stroke to the compression stroke, so as to be set to the compression stroke. [0084] Injection frequency detecting means for detecting the frequency of injection Ni is configured from part of the ECU 80 executing the processing in step S23, and the injection frequency detecting means also constitutes the engine state detecting means. [0085] According to the internal combustion engine equipped with the injection frequency detecting means, the injection timing TM is changed over from the intake stroke to the compression stroke when the pressure of the injection air reaches the basic air pressure based on detection results of the injection frequency detecting means without using a pressure sensor for detecting pressure of the injection air so that fuel atomizing is carried out using high-pressure injection air. This gives the same results as for the embodiment where whether or not the basic pressure PAO is reached is determined based on the engine rotational speed Ne. [0086] The starting sensor 84 may also start calculating timing during starting using the on or off state of a starting switch rather than the rotational speed sensor 81 or a configuration using a timer where time runs out after a prescribed period of time has elapsed may also be adopted. Further, a recoil starter may also be used as starting means. [0087] In the above embodiment, the injection timing TM of the fuel/air injection valve 30 during high-speed or high-load running of the engine E is set only to the intake stroke but may'also be set to the intake stroke and the compression stroke respectively. In this case, the fuel amount corresponding tot he running state is provided to the combustion chamber 8 separated between the intake stroke and the compression stroke. [0088] In internal combustion engine may also be a multi-cylinder internal combustion engine. Further, the internal combustion engine may be mounted on vehicles other than motorcycles, and in addition to motorcycles, may also be used as an outboard motor or as other equipment. [Description of the Numerals] 1 crankcase, 2 cylinder, 3 cylinder head, 4 head cover, 5 crankshaft, 6 piston, 7 connecting rod, 8 combustion chamber, 9 intake port, 10 exhaust port, 11 intake valve, 12 exhaust valve, 14 sparkplug, 15 intake pipe, 16 valve assembly, 17 camshaft, 18i, 18e cam I9i, 19e support shaft, 20i, 20e cam follower, 21 i, 21e rocker shaft, 22i, 22e rocker arm, 23i, 23e rod, 24, 25 sprockets, 26 timing chain, 27 valve spring, 28 cooling water pump, 30 fuel/air mixture injection valve, 31 fuel injection valve, 32 air injection valve, 33 to 35 seals, 36 fuel chamber, 37 air chamber, 40 fuel supply system, 41 fuel tank, 42 fuel pump, 43 fuel pressure regulator, 44 fuel passage system, 45 pipe, 46 fitting, 47 return fuel passage, 50 air supply system, 51 air cleaner, 52 air pump, 53 air pressure regulator, 54 air passage system, 55 rotating shaft, 56, 57 sprocket, 58 transmission chain, 59 sliding piece, 60 fitting, 61, 62 seals, 63 air introduction chamber, 64 return air chamber, 65 air passage, 66 fitting 67 return air passage, 68 passage, 69 pin, 70 orifice, 80 ECU 81 rotational speed sensor, 82 load sensor, 83 top dead center sensor, 84 starting sensor, 85 cooling water temperature sensor, 86 ignition switch, 87 switch E, LI cylinder shaft, L2 center line of rotation, D cylinder axis direction, H plane, PA set air pressure, PAO basic air pressure, PF set fuel pressure, NE engine rotational speed, Nel prescribed engine rotational speed, Ft, Fs flags t halt time, tl prescribed halt time, Ni injection frequency, Nil prescribed injection frequency, TM, TF injection timing, TA discharge timing, Ti ignition timing [Claims] A cylinder injection type internal combustion engine, having a fuel/air injection valve for directly injecting a fuel/air mixture of fuel and injection air into a combustion chamber, an air pump driven by the power of a crankshaft for discharging compressed air constituting the injection air, and control means for setting injection timing of the fuel/air injection valve, comprising: engine state detecting means for detecting an engine state of the internal combustion engine, wherein the control means sets the injection timing to the compression stroke of the internal combustion engine according to the engine state detected by the engine state detecting means, and when starting up of the internal combustion engine is detected by the engine state detecting means, the injection timing is set to the intake stroke of the. internal combustion engine and control during starting is executed. [Claim 2] The cylinder injection type internal combustion engine as disclosed in claim 1, wherein the engine state detecting means comprises rotational speed detecting means for detecting rotational speed of the engine, so that when the pressure of the injection air is detected to have reached a prescribed engine rotating speed corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the rotational speed detecting means, during starting control, the control-means switches over the injection timing from the intake stroke to the compression stroke. [Claim 3] The cylinder injection type internal combustion engine as disclosed in claim 1, wherein the engine state detecting means comprises injection frequency detecting means for detecting injection frequency of the fuel/air injection valve, so that when the pressure of the injection air is detected to have reached a prescribed injection frequency corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the injection frequency detecting means, during starting control, the control means switches over the injection timing from the intake stroke to the compression stroke. [Claim 4] The.cylinder injection type internal combustion engine as disclosed in claim 1, wherein the engine state detecting means comprises time detecting means for detecting a time of halting the internal combustion engine, so that when the halt time detected by the time detecting means is within a prescribed halt time corresponding to a state where pressure of the injection air is greater than a basic air pressure where injection of the air mixture is possible in the compression stroke when starting of the internal combustion engine is detected by the engine state detecting means, the control means sets the injection timing to the compression stroke, and when the halt time exceeds the prescribed halt time, control during starting is executed. 5. A cylinder injection type internal combustion engine substantially as hereinbefore described with reference to the accompanying drawings.

Full Text

The present invention relates to a cylinder injection type internal combustion engine equipped with a fuel/air injection valve for directly injecting a fuel/injection air mixture into a combustion chamber, and particularly relates to a cylinder injection type internal combustion engine where discharged air is compressed air from an air pump driven by the power of a crank shaft of an internal combustion engine.
[Related Art]
Conventionally, that disclosed, for example, in patent document 1, is taken as this type of cylinder injection type internal combustion engine. This internal combustion engine is equipped with a fuel injection unit for injecting a fuel-air mixture of fuel and compressed air directly into a combustion chamber and a compressor driven by a crankshaft in order to provide compressed air to an air duct communicating with the fuel injection unit. Fuel supplied to the fuel injection unit is mixed with compressed air within the fuel injection unit and is injected into the combustion chamber from the air duct together with the compressed air. An internal combustion engine with good combustibility is therefore obtained because a powerful airflow is formed due to the injected compressed air so as to promote atomization of the fuel.
However, at the time of starting up the internal combustion engine, and in particular, directly after the beginning of starting up, the amount of discharged gas for the compressor is small. Therefore, when the pressure of the compressed air within the air duct falls due to the internal combustion engine having been' stopped for a long time, it is not possible to provide compressed air of a pressure sufficient to convey the fuel to within the cylinder. Because of this, the air flow formed within the combustion chamber by the compressed air injected from the fuel injection unit is weak, it becomes difficult for the fuel to be atomized, combustibility falls, and starting performance is therefore lowered.
The internal combustion engine of patent document 1 opens a valve of the fuel injection
unit of a cylinder on a compression stroke at the time of starting up, and increases the air pressure within the air cylinder by guiding compressed air within the cylinder to within the fuel injection unit.
[Patent Document 1]
Japanese Patent Publication No. 2000-514150.
[Problems To Be Solved By The Invention]
However, in the related technology, compressed air at the time of the compression stroke bleeds via the fuel injection unit. The pressure within the cylinder therefore falls, and the starting performance of the internal combustion engine deteriorates. Further, it is necessary to control the timing of valve opening of the fuel injection unit in order to increase the air pressure within the air duct. Control of the fuel injection unit therefore becomes complex and cost is increased in cases where a pressure sensor is required to detect the pressure within the air duct. Moreover, as there is a small amount of oil mixed in with the air within the cylinder, this oil adheres to or accumulates on the walls of an air passage within the fuel injection unit as a deposit and hinders the flow of the compressed air.
In order to resolve the aforementioned situation, it is the object of the invention as disclosed in claim 1 to claim 4 to provide a cylinder injection type internal combustion engine with superior starting performance using straightforward control. It is a further object of the invention of claims 2 and 3 to reduce costs and it is an object of claim 4 to improve fuel efficiency.
Accordingly, there is provided a cylinder injection type internal combustion engine, having a fuel/air injection valve for directly injecting a fuel/air mixture of fuel and injection air into a combustion chamber, an air pump driven by the power of a crankshaft for discharging compressed air constituting the injection air, and control means for setting injection timing of the fuel/air injection valve, comprising : engine state detecting means for detecting an engine state of the internal combustion engine, wherein the control means sets the injection timing to the compression stroke of the internal combustion engine according to the engine state detected by the engine state detecting means characterized in that when starting up of the internal combustion engine is detected by the engine state detecting means, the infection timing is set to the intake stroke of the internal combustion engine and control during starting is executed. The cylinder injection type internal combustion engine, wherein the engine state detecting means comprises rotational speed detecting means for detecting rotational speed of the engine, so that when the pressure of the injection air is detected to have reached a prescribed engine rotating speed corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the rotational speed detecting means, during starting control, the control means switches over the injection timing from the intake stroke to the compression stroke.
According to this, at the time of starting up the internal combustion engine, when the rotational speed of the engine falls so that the pressure of the injection air that is rising in pressure due the compressed air ejected from the air pump driven by the power of the crank shaft is not of a sufficiently high pressure to inject a fuel-air mixture on the compression stroke, the fuel-air mixture is injected from the fuel/air injection valve at the time of the intake stroke so that the pressure within the internal combustion engine becomes negative pressure. At this time, in addition to there being a negative pressure state within the combustion chamber, the injection air has a pressure that is higher than the relatively low pressure of atmospheric air as a result of the compressed air being supplied from the air pump and the difference in pressure between the pressure of the fuel air mixture within the fuel/air injection valve and the pressure within the combustion chamber is therefore large so as to promote atomizing of the fuel within the combustion chamber. A powerful airflow is therefore formed within the combustion chamber by high-pressure injection air injected together with the fuel from the fue]/air injection valve at the time of the compression stroke according to the engine state so as to promote atomizing of the fuel. Superior combustibility can therefore be attained and a stratified combustion operation is possible.
As a result, according to the invention as disclosed in claim 1, the following results are obtained. Namely, in a cylinder injection type internal combustion engine where the injection timing to the combustion chamber of the fuel/air injection valve is set to the compression stroke according to the engine state, when starting of the internal combustion engine is detected, the injection timing is set to the intake stroke. It is therefore possible to promote atomizing of the fuel within the combustion chamber, improve combustibility during starting, and improve starting performance. Further, the air pressure at the time of the compression stroke is utilized in air injection and there is substantially no fear of the air path within the fuel/air injection valve becoming blocked up due to deposits. Further, by setting the injection timing of-the fuel/air injection valve to the compression stroke, superior combustibility is obtained, and stratified combustion is possible.
In the invention as disclosed in claim 2, in the cylinder injection type internal
combustion engine as disclosed in claim 1, the engine state detecting means comprises rotational speed detecting means for detecting rotational speed of the engine, so that when the pressure of the injection air is detected to have reached a prescribed engine rotating speed corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the rotational speed detecting means, during starting control, the control means swirches over the injection timing from the intake stroke to the compression stroke. [0012]
According to this, when pressure of the injection air reaches a basic air pressure, the injection period is switched over from the intake stroke to the compression stroke based on detection results of the rotational speed detecting means and atomizing of the fuel is carried out using high-pressure injection air without having to use a pressure sensor for detecting pressure of the injection air.
[0013] As a result, according to the claim 2 of the invention, in addition to the results of the invention disclosed in claim 1, the following results are attained. A pressure sensor is therefore not required to detect pressure of the injection air, costs can be reduced, and atomizing of fuel can be carried out using high-pressure injection air so as to ensure good starting performance. [0014]
With the invention disclosed in claim 3, the cylinder injection type internal combustion engine disclosed in claim 1 is such that, the engine state detecting means comprises injection frequency detecting means for detecting injection frequency of the fuel/air injection valve, so that when the pressure of the injection air is detected to have reached a prescribed injection frequency corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the injection frequency detecting means, during starting control, the control means switches over the injection timing from the intake stroke to the compression stroke. [0015]
According to this, when pressure of the injection air reaches a basic air pressure, the injection period is switched over from the intake stroke to the compression stroke based on detection results of the injection frequency detecting means after completion of control during starting and atomizing of the fuel is carried out using high-pressure injection air without having to use a pressure sensor for detecting pressure of the injection air. As a result, according to the claim 3 of the invention,
the same results as for the invention of claim 2 are attained. [0016]
Tn the invention as disclosed in claim 4, with the cylinder injection type internal combustion engine as disclosed in claim 1, the engine state detecting means comprises time detecting means for detecting a time of halting the internal combustion engine, so that when the halt time detected by the time detecting means is within a prescribed halt time corresponding to a state where pressure of the injection air is greater than a basic air pressure where injection of the air mixture is possible in the compression stroke when starting of the internal combustion engine is detected by the engine state detecting means, the control means sets the injection timing to the compression stroke, and when the halt time exceeds the prescribed halt time, control during starting is executed. [0017]
According to this, because the halt time from the time of halting operation for the previous time for the internal combustion engine to the timing for starting the start up on this occasion is within a prescribed halt time, there is substantially very little or no drop in pressure of the injection air due to leaking of compressed air from between slight gaps existing in the air supply system etc. from the air pump to the fuel/air injection valve. When the pressure of the injection air is then greater than the basic air pressure at the starting timing, fuel/air mixture can be injected in the compression stroke without executing control during starting. A powerful airflow is therefore formed within the combustion chamber by injection air of a pressure greater than the basic air pressure and fuel atomizing is promoted. It is therefore possible to obtain superior combustibility and stratified combustion operation is possible directly after the start of starting-up. [0018]
As a result, according to the claim 4 of the invention, in addition to the results of the invention disclosed in claim 1, the following results are attained. Namely, even when an internal combustion engine is in a start state, when the halt time of an internal combustion engine is within a prescribed halt time, it is possible to improve combustibility by carrying out injection of an air-fuel mixture using high-pressure injection air without carrying out control during starting, superior starting performance is ensured, and the start timing of a stratified combustion operation is made to come about more quickly, so that fuel consumption is dramatically improved. [0019]
[Brief Description of the Drawings]
FIG. 1 is a partial cross-sectional view of a plane orthogonal to a central line of
rotation L2 of a crankshaft of a multi-cylinder injection-type internal combustion
engine constituting an embodiment of the present invention, and is as viewed from
I of FIG. 3 and FIG. 5.
FIG. 2 is a cross-sectional view of a plane perpendicular to a central line of rotation
of a crankshaft containing a cylinder axis line for a crankcase and cylinder of the
internal combustion engine of FIG. 1, and is a cross-sectional view as viewed from
II—II of FIG. 5 for a cylinder head.
FIG. 3 is a cross-sectional view from III—III of FIG. 5.
FIG. 4 is an enlarged view of essentia] parts of a cylinder head and head cover of
FIG. 2, and is a cross-sectional view from IV-IV of FIG. 8 of the vicinity of an air
pressure regulator.
FIG. 5 is a view from V of FIG. 1 when the head cover is outside.
FIG. 6 is a partial cross-sectional view mainly from VI-VI of FIG. 5 of essential
parts.
FIG. 7 is a schematic view illustrating a fuel supply system and air supply system
for a fuel/air mixture valve of the internal combustion engine of FIG. 1.
FIG. 8 is a view of the head cover from VIII of FIG. 1.
FIG, 9 is a flowchart illustrating a routine for control during starting for injection
timing of a fuel/air mixture valve of the internal combustion engine of FIG. 1.
FIG. 10 is a schematic view illustrating injection timing for a fuel/air mixture valve
and fuel injection valve of the internal combustion engine of FIG. 1, discharge timing
of an air pump, and ignition timing, where FIG. 10(A) is a view for when the fuel/air
injection valve injects a fuel/air mixture on the intake stroke, and FIG. 10(B) is
a view when the fuel/air injection valve injects a fuel/air mixture on the compression
stroke.
FIG. 11 is a flowchart illustrating a routine for control during starting for
injection timing of a fuel/air mixture valve of a multi-cylinder injection-type
internal combustion engine constituting a further embodiment of the present
invention.
[Embodiments]
In the following, a description is given of embodiments of the present invention with
reference to FIG. 1 to FIG. 11. Referring to FIG. 1 to FIG. 3, an cylinder injection
type internal combustion engine E to which the present invention is applied is a
water-cooled single-cylinder four-stroke internal combustion engine mounted on a
vehicle constituted by a motorcycle, and is equipped with an engine body comprised
of a crankcase 1 forming a crank chamber housing a crankshaft 5, a cylinder 2 connected
to an upper end of the crankcase 1, a cylinder head 3 coupled to the upper end of
the cylinder 2, and a head cover 4 coupled to an upper end of the cylinder head 3.
[0020]
The internal combustion engine E is arranged so as to be laid so that the crankshaft
5 extends in a direction from left to right of the vehicle (vehicle width direction)
so as to be suspended at the vehicle in a state where the cylinder 2 positioned to
the front of the vehicle with respect to the crankshaft 5 is inclined slightly upwards
with respect to the vehicle (refer to FIG. 1 and FIG. 2).
[0021]
In this embodiment, with regards to the body of the internal combustion engine E,
in the direction D of a cylinder shaft line LI, an upward direction is the direction
where the cylinder head 3 is positioned with respect to the cylinder 2.
[0022]
A piston 6 fitted so as to be reciprocally moveable at a cylinder hole 2a of the
cylinder 2 is coupled to the crankshaft 5 supported in a rotatable manner at the
crankcase 1 via a connecting rod 7. A combustion chamber 8 constituted of a recess
3a formed at the lower surface of the cylinder head 3 and a cavity 6a formed at the
top surface of the piston 6, between the piston 6 and the cylinder head 3.
[0023]
Referring to FIG. 4, an intake port 9 having a pair of intake openings 9a opening
at the combustion chamber 8 and an exhaust port 10 having a single exhaust opening
10a opening at the combustion chamber 8 are formed at the cylinder head 3 and are
provided with a pair of intake valves 11 opening and closing the pair of intake
openings 9a and a single exhaust valve 12 opening and closing the exhaust opening
10a. A fuel/air injection valve 30 and sparkplug 14 are fitted facing the combustion
chamber 8.
[0024]
The fuel/air injection valve 30 is arranged at a substantially central part of the
combustion chamber 8 as viewed from a cylinder axis line direction D so as to have
an axial line of substantially the same axis as that of the cylinder shaft line LI so as to directly inject a fuel-air mixture of fuel and compressed air into the combustion chamber 8. Both of the intake valves 11, the exhaust valve 12 and the sparkplug 14 are arranged spaced apart in a circumferential direction about the periphery of the fuel/air injection valve 30 taking the fuel/air injection valve 30 as center. [0025]
An intake pipe 15 of an intake device having an air cleaner 51 (refer to FIG. 7) and a throttle body is connected so as to communicate with an inlet 9b at a side surface of the intake side of the cylinder head 3 at which the inlet 9b of the intake port
9 opens, and an exhaust pipe of an exhaust device is connected to the side surface
of an exhaust side of the cylinder head 3 at which an outlet 10b of the exhaust port
10 opens.
[0026]
Here, intake side refers to the side where the intake port 9 is positioned with respect to a plane H parallel with a rotation center line L2 of the crankshaft 5 containing the cylinder shaft line LI at the engine body, and exhaust side refers to the side where the exhaust port 10 is positioned with respect to plane H at the engine body. [0027]
Intake air provided from the intake device via the intake pipe 15 is drawn into the combustion chamber 8 via the pair of opened intake valves 11 from the intake ports 9 when the piston is on the downward intake stroke. Fuel injected into the combustion chamber 8 from the fuel/air injection valve 30 in a state mixed with air is combusted by a spark from the sparkplug 14 after being compressed by the rising piston 6 on the compression stroke, and the piston 6 falling due to the pressure of the combusted gas on the expansion stroke rotates the crankshaft 5 via the connecting rod 7. On the exhaust stroke, the combusted gas is exhausted from the combustion chamber 8 to the exhaust port 10 as exhaust gas via the open exhaust valve 12 and is further exhausted to the outside via the exhaust device. [0028]
Referring to FIG. 1 to FIG. 5, a valve assembly 16 for opening and closing the intake valves 11 and the exhaust valve 12 is comprised of a cam shaft 17 an intake cam 18i and an exhaust cam 18e supported in a rotatable manner at side parts of the cylinder 2, an intake cam follower 20i making contact with the intake cam 18i and an exhaust cam follower 20e making contact with the exhaust cam 18e respectively supported in a swingable manner at a pair of support shafts 19i, 19e supported at the cylinder
2, intake rocker arms 22i making contact with tips of valve stems of the pair of intake
valves 11 and an exhaust rocker arm 22e making contact with the tip of a valve stem
of the exhaust valve 12 supported respectively in a swingable manner at a pair of
rocker shafts 21i, 21e supported at the cylinder head 3, and a pair of rods 23i, 23e,
making contact with the ends of the cam follower 20i and exhaust cam follower 20e
and the intake rocker arm 22i and exhaust rocker arm 22e, and transmitting the rocking
action of the cam follower 20i and the exhaust cam follower 20e to the intake rocker
arm 22i and exhaust rocker arm 22e.
[0029]
As shown in FIG. 1, the cam shaft 17 is rotatably driven at a rotational speed that
is half the rotational speed of the cam shaft 17 by driving force of a crankshaft
5 transmitted via a transmission mechanism containing a drive sprocket 24 provided
at the crankshaft 5, a cam sprocket 25 provided at cam shaft 17 and a timing chain
26 spanning the sprockets 24 and 25. The intake cam 18i and the exhaust cam 18e rotating
together with the cam shaft 17 open and close the pair of intake valves 11 and the
exhaust valve 12 urged in a valve-closing direction by a valve spring 27 at prescribed
opening and closing timings in synchronization with rotation of the crankshaft 5 via
the intake cam follower 20i and the exhaust cam follower 20e, a pair of rods 23i,
23e, the intake rocker arms 22i, and the exhaust rocker arm 22e.
[0030]
Referring to FIG. 3 and FIG. 6, the fuel/air injection valve 30 fitted so as to extend
at the cylinder head 3 and the head cover 4 directly injects a fuel/air mixture formed
of fuel and injection air into the cavity 6a of the combustion chamber 8.
[0031]
The fuel/air injection valve 30 is comprised of a fuel injection valve 31, inserted
into an insertion tube 4c formed at the head cover 4, for injecting fuel provided
via a fuel supply system 40 (refer to FIG. 7), and an air injection valve 32, inserted
into an insertion tube 3c formed at the cylinder head 3, for injecting a fuel/air
mixture of fuel injected from the fuel injection valve 31 and injection air provided
via an air supply system 50 (refer to FIG. 7) from a nozzle 32a having a valve body
32al opening and closing a nozzle hole (not shown) to within the combustion chamber
8.
[0032]
An annular fuel chamber 36 sealed by a pair of annular seals 33, 34 fitted about the
outer periphery of a valve body 31b of the fuel injection valve 31 is formed so as
to encompass the valve body 31b. Fuel is supplied to the fuel chamber 36 from the
fuel supply system 40. An annular air chamber 37 sealed by a seal 34 and an annular seal 35 fitted about the outer periphery of the valve body 32b of the air injection valve 32 is formed so as to encompass a nozzle section 31a of the fuel injection valve 31 and an air introducing section 32c of the air injection valve 32 between the insertion tube 4c, fuel injection valve 31 and air injection valve 32. Compressed air from the air supply system 50 is supplied as injection air at the air chamber 37.
[0033]
The amount of fuel contained in the fuel/air mixture injected from the fuel/air injection valve 30, injection timing TM (refer to FIG. 10) of the fuel/air injection valve 30 and the injection amount are set by electronic control means (hereinafter referred to as "ECU") 80 (refer to FIG. 1) taken as control means according to engine conditions such as engine load of the internal combustion engine E, engine rotational speed Ne, and engine temperature etc. detected by engine state detecting means described later. Further, spark timing Ti (refer to FIG. 10) of the sparkplug 14 is also controlled by the ECU 80 according to the engine states. [0034]
The fuel injection valve 31 and the air injection valve 32 are comprised of a solenoid valve driven to open and close by a signal from the ECU 80. The fuel injection valve 31 injects fuel flowing from the fuel chamber 36 through a fuel introduction opening 31c formed in the valve body 31b from the nozzle section 31a through the air introducing section 32c and into the valve body 32b of the air injection valve 32 at an injection timing TF (refer to FIG. 10) and fuel amount set by the ECU 80 according to the engine states. After this, the air injection valve 32 injects a fuel/air mixture of fuel within the valve body 32b and injection air within the valve body 32b and of the air chamber 37 from the facing nozzle section 32a within the combustion chamber 8 towards the cavity 6a at an injection timing and injection amount that is the injection timing TM and the injection amount of the fuel/air injection valve 30. [0035]
Referring to FIG. 7, the fuel supply system 40 is comprised of an electric-powered fuel pump 42 for force-feeding liquid fuel pumped from a fuel tank 41 at high-pressure, a fuel pressure regulator 43 for regulating pressure of fuel supplied from the fuel pump 42 to the fuel chamber 36 to a set fuel pressure PF, and a fuel passage system 44 communicating with the fuel pump 42, fuel pressure regulator 43 and fuel chamber 36. Referring to FIG. 6 and FIG. 8, fuel at the set fuel pressure PF is supplied to the fuel chamber 36 via a fuel passage 44c comprised of holes formed in the head cover
4 via a fitting 46 to which a pipe 45 is connected. Fuel passages 44a, 44b and a fuel passage 44c formed respectively by the pipe 45 and the fitting 46 constitute part of the fuel passage system 44. Surplus fuel of the fuel discharged from the fuel pump 42 is returned to the fuel tank 41 from the fuel pressure regulator 43 via a return fuel passage 47. [0036]
Referring to FIG. 5 to FIG. 7, the air supply system 50 is comprised of an air pump 52 discharging air drawn in from an air cleaner 51 of the intake device driven by the power of the crankshaft 5, an air pressure regulator 53 for regulating the pressure of the injection air constituted by the compressed air discharged from the air pump 52 supplied to within the air chamber 37 to a set air pressure PA, and an air passage system 54 communicating with the air pump 52, air pressure regulator 53, and air chamber 37. The set air pressure PA is a pressure capable of enabling injection of a fuel/air mixture from the fuel/air injection valve 30 in the compression stroke and preferably in the latter half of the compression stroke, and is set to be a pressure that is as low as possible to enable injection of the fuel/air mixture in the compression stroke while being higher than a basic air pressure PAO. [0037]
The air pump 52 provided at the exhaust side of the cylinder 2 is a displacement-type reciprocal-type pump for discharging compressed air of a pressure higher than the set air pressure PA at a discharge timing TA described later and is comprised of a pump body 52a formed integrally with the cylinder 2, a pump cover 52b coupled via a gasket 52c constituted by a thin plate at the pump body 52a, a rotating shaft 55 rotatably drive by the force of the crankshaft 5 supported in a rotatable manner at the cylinder 2, and a piston 52d coupled to the rotating shaft 55 forming a pump chamber 52e with a pump cover 52b inserted in a manner capable of reciprocal movement at the pump body 52a. [0038]
An intake section formed from an intake path 52fl provided with an intake valve comprised of a reed valve taking part of a gasket 52c as a reed body and a discharge section 52g formed with a discharge path 52gl provided with a discharge valve 52h having a valve body 52hl urged by a spring 52h2 are formed at the pump cover 52b. Referring to FIG. 1 and FIG. 3, the rotating shaft 55 is rotatably driven at the same speed as the cam shaft 17 by power of the crankshaft 5 transmitted via a transmission mechanism comprised of a drive sprocket 56 provided at the crankshaft 5, a driven sprocket 57 provided at the rotating shaft 55 and a transmission chain 58 spanning
the sprockets 56, 57.
[0039]
The pump cover 52b and the discharge section 52g are as a whole arranged next to the
exhaust side of the cylinder head 3, are positioned to the side of the cylinder head
3 from a joining surface 3d, and the uppermost end of the pump chamber 52e is positioned
substantially above the joining surface 3d. Further, the whole of the air chamber
37 is positioned more towards the air pump 52 than the fuel chamber 36.
[0040]
The piston 52d is coupled to the rotating shaft 55 via a Scotch yoke mechanism.
Specifically, the piston 52d is coupled via a sliding piece 59 fitting in a sliding
manner into a columnar guide hole formed at the piston 52d to an eccentric shaft 55a
provided eccentrically from a centerline of rotation of the rotating shaft 55 at one
end of the rotating shaft 55, so as to be made to move in a reciprocal manner in an
axial direction of the pump body 52a within the pump body 52a due to rotation of the
rotating shaft 55. A transmission mechanism for rotatably driving an impeller of a
cooling water pump 28 is provided at the other end of the rotating shaft 55.
[0041]
Air drawn into the pump chamber 52e from the intake path 52fl via the a fitting 60
to which a pipe communicating with the air cleaner 51 is connected is compressed to
a high pressure by the piston 52d, the discharge valve 52h is opened, and the air
is discharged at the discharge path 52gl as compressed air.
[0042]
Referring to FIG. 4 and FIG. 8, the air pressure regulator 53 is fitted to the head
cover 4 so as to be partially contained in a storage section 4d integrally formed
at an intake side of the head cover 4. The air pressure regulator 53 is comprised
of a first case 53a contained in a storage chamber 4e formed at the storage section
4d and a second case 53b positioned at an outside part of the storage chamber 4e so
as to be covered by a cover 53c. An air introduction chamber 63 sealed by a pair of
annular seals 61, 62 fitted to the first case 53a so as to encompass the first case
53a between the seals 61 and 62 and a return air chamber 64 encompassing an air
discharge section 53al of the first case 53a between the seal 62 and the bottom of
the storage section 4d are formed between the storage section 4d and the first case
53a. At the return air chamber 64, surplus air discharged from the air pressure
regulator 53 during pressure regulation is guided along the air discharge section
53a 1.
[0043]
An air guide hole 53d for guiding outside air as fluid having standard pressure during correction of the set air pressure PA is formed at the second case 53b. The outside air flows from a gap 53e formed between the storage section 4d and the cover 53c into a gap 53f formed between the second case 53b and the cover 53c so as to flow into the air pressure regulator 53 from the air guide hole 53d opened in the gap 53f. [0044]
Referring to FIG. 7, the air introduction chamber 63 guides air having the set air pressure PA taken as a fluid having a reference pressure during correction of the set fuel pressure PF of the fuel pressure regulator 43 according to the pressure within the air chamber 37 so that the air communicates with the fuel pressure regulator 43 via an air passage partially constituted by a passage 65a formed at the storage section 4d. Further, the return air chamber 64 communicates with the air cleaner 51 via a return air path 67 formed from a fitting 66 fitted to the storage section 4d and piping (not shown) connected to the fitting 66, etc. Surplus air of compressed air discharged from the air pump 52 is circulated back to the air cleaner 51 from the air pressure regulator 53 via the return air path 67. [0045]
Referring to FIG. 5 to FIG. 8, the air passage system 54 is comprised of an air passage 54a formed by a pipe 68 connected to an outlet of the discharge path 52gl of the pump cover 52b, a head-side air passage 54b comprised of a hole formed in the cylinder head 3, a cover-side air passage 54c comprised of a hole formed in the head cover 4, a connection air passage 54d formed from a hollow positioning pin 69 provided at the surface where the cylinder head 3 and the head cover 4 join in order to connect the head-side air passage 54b and the cover-side air passage 54c, and a branching air passage 54e branching from the cover-side air passage 54c. [0046]
The branching air passage 54e comprised of a hole formed in the head cover 4 communicates with the air chamber 37 and the air pressure regulator 53 via the cover-side air passage 54c. An orifice 70 (refer also to FIG. 4) is provided at the branching air passage 54e. By using this orifice 70, the pressure of the injection air within the air chamber 37 can be kept higher than the set air pressure PA at the timing of emission of compressed air of a pressure higher than that of the set air pressure PA from the air pump 52 at a prescribed time from the emission start timing of the air pump 52. The orifice 70 therefore constitutes a high-pressure maintaining structure for temporarily keeping the injection air pressure at a higher pressure than that of the set air pressure PA at least until a timing coinciding with the
injection start timing of the fuel/air injection valve 30. Further, pulsing of the compressed air guided by the air pressure regulator 53 is suppressed by the orifice 70 and the precision of the regulating function of the air pressure regulator 53 is improved. [0047]
Further, by arranging the pipe 68 on the exhaust side of the cylinder 2 and forming the head-side air passage 54b and the cover-side air passage 54c on the exhaust side of the cylinder head 3 and the exhaust side of the head cover 4 respectively, of the air passage system 54, the air passages 54a, 54b and 54c reaching the air chamber 37 from the air pump 52 can be provided on the exhaust side of the cylinder head 3 and the exhaust side of the head cover 4 for which the temperature is high compared with the intake side because of exhaust gas flowing through the exhaust port 10. [0048]
Next, a description is given of control of the fuel/air injection valve 30 using the discharge timing TA of compressed air from the air pump 52and the ECU 80 with reference to FIG. 1, FIG. 3, FIG. 9 and FIG. 10. Referring to FIG. 1, detection signals from engine state detecting means comprised of a rotational speed sensor 81 for detecting rotation speed of the crankshaft 5 constituting rotational speed detecting means for detecting rotational speed Ne of the internal combustion engine E, a load sensor 82 for detecting opening of a throttle valve provided at the intake device constituting load detecting means for detecting engine load, a top dead center sensor 83 for detecting rotational position of the rotating shaft 55 constituting top dead center detecting means for detecting top dead center of a compression stroke of the internal combustion engine E, a starting sensor 84 constituting starting detecting means for detecting when the internal combustion engine E is in a starting state, a circulating water temperature sensor 85 constituting engine temperature detecting means for detecting engine temperature, an ignition switch 86 for putting an ignition circuit for controlling energizing of the sparkplug 14 in an operating state or a non-operating state, and a switch 87 for putting the ignition circuit in an operating state or non-operating state constituting idling stop detection means for detecting operation or non-operation of the idling stop control device based on a signal from the idling stop control device for putting the internal combustion engine E in a halted state at times of temporary stopping such as at an intersection etc. are inputted to the ECU 80. [0049] Here, the starting state of the internal combustion engine E is an operating state
from a starting timing where a starting motor (not shown) taken as starting means is made to operate by a starting switch being put in an on state so that the crankshaft 5 currently in a stationary state starts to rotate to a starting completion timing where the internal combustion engine E is in a purely combustive state. In this embodiment, the starting sensor 84 is configured so as to utilize a rotational speed sensor 81, with the starting state taken to be when the engine rotational speed Ne is within the range of rotational speed from zero for a starting commencement timing to the engine rotational speed Ne at the timing where starting is complete. [0050]
Further, control programs for controlling injection timing TF of injection of fuel injected from the fuel injection valve 31 and the amount of fuel (here, this is equivalent to the valve opening time) and controlling the injection timing TM and injection amount (which in this case is equivalent to the valve opening time) of injection timing TM and injection amount of the fuel/air mixture injected from the air injection valve 32, i. e. from the fuel/air injection valve 30 and various maps, with the ECU 80 controlling the fuel/air injection valve 30 in accordance with these control programs. [0051]
In the following, a description is given with reference to FIG. 3, FIG. 9 and FIG. 10 of control of the fuel/air injection valve 30 at the time of the starting state of the internal combustion engine E. Referring to the flowchart of FIG. 9 for illustrating the control routine for the time of starting of the fuel/air injection valve 30, in step SI, a halt time determination flag Ft is set to 1 at the time of starting up this routine in order to carry out a determination in a step S6 once. [0052]
Next, in step S2, a determination is made as to whether or not the ignition circuit is in an operating state, i.e. as to whether or not the ignition switch 86 and the switch 87 are both on, and when this determination is negative the routine is ended. When the switch 87 is on, the idling stop control device is in an non-operating state and an idling stop is not carried out. When the switch 87 is in an off state, the ignition circuit is in a non-operating state and the idling stop control device is in an operating state, so that idling stopping is carried out. When the determination of step S2 is affirmative, the rotational speed Ne of the engine detected by the rotational speed sensor 81 is read-in in step S3. Before commencement of starting, the engine rotational speed Ne is zero. [0053]
Proceeding to step S4, a determination is made as to whether or not the internal
combustion engine E is in a starting state based on a detection signal from the
starting sensor 84. When this determination is negative, the internal combustion
engine is operating in a state other than a starting state. Step S15 is then proceeded
to and a determination is made as to whether or not the ignition circuit is in a
non-operating state due to the ignition switch 86 and the switch 87 being in off states.
When this determination is negative, the internal combustion engine E is in an
operating state, step S3 is returned to and execution of the processing of this routine
continues to be executed.
[0054]
When the determination of step S4 is affirmative, when the internal combustion engine
E is in the starting state, step S5 is proceeded to and flag Ft is referred to. When
flag Ft is set to 1 so that it is necessary to determine whether or not the stop time
t is within a prescribed stop time tl, step S6 is proceeded to. When the determination
of step S5 is negative, determination of the stop time t has already been executed.
Step Sll is then proceeded to and a determination is then made as to whether or not
control during starting of the injection timing TM (refer to FIG> 10) of the fuel/air
injection valve 30 is to be carried out.
[0055]
In step S6, a determination is made as to whether or not stop time t detected by a
timer constituting time detecting means for detecting the stop time of the internal
combustion engine E from the stop timing of the previous time to the starting
commencement timing of this time is within a prescribed stop time tl corresponding
to the state where the pressure of the injection air is greater than the basic air
pressure PA0. This timer is also constituted by the engine state detecting means for
detecting engine states of the internal engine E.
[0056]
The pressure of the injection air gradually falls as the stop time t elapses due to
leaking of compressed air from slight gaps in the air supply system 50 formed of the
cylinder 2, cylinder head 3, and head cover 4 etc. due to the operation of the air
pump having stopped at the time of stopping the internal combustion engine E. The
basic air pressure PA0 is the lowest possible pressure capable of enabling injection
of the fuel/air mixture from the fuel/air injection valve 30 on the compression
stroke.
[0057]
Therefore with normal temporary stopping of the internal combustion engine E and
idling stops etc., at the time of a restarting operation within a short time after stopping the internal combustion engine E, the stop time t is comparatively short. The fall in pressure of the injection air is therefore substantially non-existent or small, and the pressure of the injection air is a value greater than the basic air pressure PAO. Because of this, after a stop time that is a short time such as for an idling stop, when the internal combustion engine E is re-started, the determination in step S6 is affirmative, and step S8 is proceeded to after the flag Ft is set to zero in step S7. In step S8, the injection air is of a pressure greater than the basic air pressure PAO and injection of the fuel/air mixture in the compression stroke is possible and it is therefore not necessary to inject the fuel/air mixture on the intake stroke. A starting time control flag Fs can then be set to zero in order to indicate that control during starting of the injection timing TM is not executed. [0058]
As the stop time t is long, time corresponding to the state where the pressure of the injection air is lower than the basic air pressure PAO elapses. Therefore, when the determination of step S6 is negative, in step S9, the flag Ft is set to zero, and step S10 is proceeded to. In step S10, the injection air is at a pressure lower than the basic air pressure PAO and injection of the fuel/air mixture at the time of the compression stroke is difficult. Flag Fs is then set to 1 in order to indicate that control during starting is executed to set the injection timing TM at the intake stroke, and step Sll is proceeded to. [0059]
Then, in step Sll, when the flag Fs is 1, step S12 is proceeded to and a determination is made as to whether or not the engine rotational speed Ne has reached a prescribed engine rotation speed Nel. This prescribed engine rotational speed Nel is the engine rotational speed Ne corresponding to when the pressure of the injection air within the air chamber 37 reaches the basic pressure PAO and is set in advanced based on experimentation etc. [0060]
When the determination of step S12 is negative, i.e. when it is determined that the pressure of the injection air within the air chamber 37 has not reached the basic air pressure PAO, step S13 is proceeded to, and the injection timing TM of the fuel/air injection valve 30 is only set for the intake stroke. As shown in FIG. 10(A), in advance of the injection timing TM, fuel injected at an injection timing TF from the fuel injection valve 31 is injected in the direction of the combustion chamber 8 which
is at negative pressure due to being at an intake stroke together with the injection air one time every cycle of the internal combustion engine E. As a result of the injection of the fuel/air mixture on this intake stroke, a substantially homogenous fuel/air mixture is formed within the whole of the combustion chamber 8 up to the ignition timing Ti prior to the compression top dead center point, and this homogenous fuel/air mixture can then be combusted in a homogenous manner. [0061]
More specifically, when one cycle is carried out in the order of an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke, at each cycle, the injection timing TF of the fuel injection valve 31 is set to the first half of the exhaust stroke, and the injection timing TM (the injection timing of the air injection valve 32) of the fuel/air injection valve 30 is set to be a timing that is slower than the injection timing TF and is set here to the first half of the intake stroke. [0062]
At this time, when a long period of time has elapsed from the internal combustion engine E being stopped to the extent that the air pressure within the air chamber 37 becomes equal to the atmospheric pressure of the outside air due to leaking of compressed air from slight gaps in the air supply system 50, at the injection timing TF on the current cycle shown in FIG. 10(A), fuel injected from the fuel injection valve 31 is injected into the combustion chamber 8 together with the injection air having an increased air pressure for the previous cycle and injection air having air pressure equal to the atmospheric pressure at the time of the initial cycle after the current cycle commences starting. At the cycle for this time, compressed air discharged at the discharge timing TA of the air pump 52 set to span from the first half of the compression stroke to the second half is such that the pressure of the injection air within the air chamber 37 is raised, and the raised injection air is injected into the combustion chamber 8 together with the fuel on the next cycle. In the case where time that elapses from when the internal combustion engine E is stopped is not to the extent that the air pressure within the air chamber 37 becomes equal to the atmospheric pressure, the fuel/air mixture is injected using injection air of a pressure higher than the atmospheric pressure from commencement of starting. [0063]
As a result of using the series of steps of step S4 to S6, and S9 to S13, when the air pressure of the injection air becomes lower than the basic air pressure PA0 and the internal combustion engine E then commences starting with the stop state having spanned a length of time sufficient, for example, for the air pressure of the injection
air to become equal to the atmospheric air pressure, the compression timing TM can always be set to the intake stroke. [0064]
When the determination of step S12 is affirmative, the injection air pressure is greater than the basic air pressure PAO. Step S14 is then proceeded to, and the injection timing TM of the fuel/air injection valve 30 is switched over from the intake stroke to the compression stroke, and set to the compression stroke. As shown in FIG. 10(B), in advance of the injection timing TM, fuel injected at an injection timing TF from the fuel injection valve 31 is injected in the direction of the combustion chamber 8 which is at negative pressure due to being at an intake stroke together with the injection air one time every cycle of the internal combustion engine E. At this time, fuel/air mixture injected from the fuel/air injection valve 30 mostly collects within the cavity 6a, and in order to prevent or suppress dispersion at the combustion chamber 8, stratified combustion is carried out so as to combust the fuel/air mixture with a fuel/air mixture of good combustibility existing in the vicinity of the sparkplug 14 with an air layer that does not include fuel being present at the periphery of the cavity 6a. [0065]
More specifically, at each cycle, discharge timing TF of the fuel injection valve 31 is set to a higher timing than the discharge timing TA of, for example, the latter half of the intake stroke, with respect to the discharge timing TA of the air pump 52 set spanning from the former half of the compression stroke to the latter half. The discharge timing TM of the fuel/air injection valve 30 (also the discharge timing of the air injection valve 32) is a timing partially overlapping with the discharge period TA, does not overlap with the discharge timing TA, and is set to the latter half of the compression stroke at a timing that is slightly slower than the discharge timing TA. In either case, the injection timing TM is set to overlap with a timing period such that the pressure of injection air within the air chamber 37 is held at a state higher than the set air pressure PA. [0066]
In the starting state, the engine state from the commencement of starting until a prescribed engine rotational speed Nel is reached is a first engine state corresponding to a state where the pressure of the injection air is less than the basic air pressure PAO. At the time of this first state, the injection timing TM of the fuel/air injection valve 30 is set to the intake stroke. In the starting state, the engine state when the prescribed engine rotational speed is Nel or more is a second
engine state corresponding to a state where the pressure of the injection air is the basic air pressure PA () or more. At the time of this second state, the injection timing TM of the fuel/air injection valve 30 is set to the compression stroke. [0067]
In relation to step S4, when the internal combustion engine E operates in a state other than at the time of starting, the injection period TM is set at the compression stroke or the intake stroke according to the engine state by the ECU 80. For example, directly after completion of starting of the internal combustion engine E, the injection timing TM of the fuel/air injection valve 30 is set to the latter half of the compression stroke as shown in FIG. 10(B) in a partial running region of the internal combustion engine E such as during idling and low-speed or low-load running, and stratified combustion is carried out. Further, in a separate running region of the internal combustion engine E for the time of high-speed or high-load running of the internal combustion engine E etc., the injection timing TM of the fuel/air injection valve 30 is set to the intake stroke, a substantially homogeneous fuel/air mixture is formed in the whole of the combustion chamber 8, and uniform combustion is carried out. [0068]
When the determination of step S4 is negative and the determination of step S15 is affirmative, then running of the internal combustion engine E has stopped, with this including idling stops. At this time, step S16 is proceeded to, and after the timer is reset, a count is started, and this routine ends. Then, the processing from step S3 to step S14 is executed every prescribed period by the ECU 80 until the determination of step S4 is negative due to starting being complete. [0069]
The following is a description of the operation and effects of the embodiment with the configuration described above. In an internal combustion engine E equipped with the air pump 52 driven by the power of the fuel/air injection valve 30 and the crankshaft 5 and an ECU 80 for setting the injection timing TM of the fuel/air injection valve 30 to the intake stroke or the compression stroke according to the engine state detected by the engine state detecting means, when starting of the internal combustion engine E is detected by the starting sensor 84, the ECU 80 executes control at the time of starting for setting the injection timing TM to the intake stroke so that at the time of starting the internal combustion engine E, a fuel/air mixture is injected from the fuel/air injection valve 30 at the time of the intake stroke where the pressure within the combustion chamber 8 when the speed of the engine
Ne becomes low so that the pressure of the injection air raised in pressure by compressed air discharged from the air pump 52 driven by the power of the crankshaft 5 is not of sufficiently high pressure to inject the fuel/air mixture on the compression stroke. At this time, in addition to there being a negative pressure state within the combustion chamber 8, the injection air has a pressure that is higher than the relatively low pressure of atmospheric air as a result of the compressed air being supplied from the air pump 52 and the difference in pressure between the pressure of the fuel air mixture within the fuel/air injection valve 30 and the pressure within the combustion chamber 8 is therefore large so as to promote atomizing of the fuel within the combustion chamber 8. A powerful airflow is therefore formed within the combustion chamber 8 by high-pressure injection air injected together with the fuel from the fuel/air injection valve 30 at the time of the compression stroke so as to promote atomizing of the fuel. Superior combustibility can therefore be attained and a stratified combustion operation is possible. [0070]
As a result, atomizing of the fuel within the combustion chamber 8 is promoted, combustibility during starting is improved, and starting performance is also improved using simple control where the injection timing TM is changed to the intake stroke when starting of the internal combustion engine E is detected. Further, the air pressure within cylinder hole 2a at the time of the compression stroke is utilized in air injection and there is substantially no fear of the air path within the fuel/air injection valve 30 becoming blocked up due to deposits. Further, by setting the injection timing TM of the fuel/air injection valve 30 to the compression stroke, superior combustibility is obtained, and stratified combustion is possible. [0071]
When a prescribed engine rotational speed Nel corresponding to the pressure of injection air reaching a basic pressure PA0 where injection of the fuel/air mixture in the compression stroke is possible is detected by the rotational speed sensor 81 constituting the engine state detecting means used for calculating fuel amount of the fuel/air injection valve 30 and injection timing period, the injection timing TM is switched over from the intake stroke to the compression stroke when the pressure of the injection air reached the basic air pressure PA0 based on detection results of the rotational speed sensor 81 without using a pressure sensor to detect pressure of the injected air and fuel atomizing is carried out using injection air of a pressure in excess of the basic air pressure PA0. [0072]
A pressure sensor is therefore not required to detect pressure of the injection air, costs can be reduced, and atomizing of fuel can be carried out using high-pressure injection air so as to ensure good starting performance. [0073]
When the halt time detected by the timer when starting of the internal combustion engine E is detected is within a prescribed halt time tl corresponding to a state where the injection air pressure is greater than the basic air pressure PAO, the ECU 80 sets the injection timing TM to the compression stroke. When the halt time t exceeds the prescribed halt time tl, as a result of execution of control at the time of starting, the halt time t from the running halt timing for the previous time of the internal combustion engine E to the running start period for this time is within the prescribed halt time t. Fall in pressure of injection air due to leaking of compressed air from minute gaps in the air supply system 50 and air chamber 37 from the air pump 52 to the fuel/air injection valve 30 is almost non-existent or small. The fuel/air mixture can therefore be injected on the compression stroke when the pressure of the injection air at the commencement of starting timing is greater than the basic air pressure PAO without executing control at the time of starting. A powerful airflow is therefore formed within the combustion chamber 8 by injection air of a pressure greater than the basic air pressure PAO and fuel atomizing is promoted. It is therefore possible to obtain superior combustibility and stratified combustion operation is possible directly after the start of starting-up. [0074]
As a result, even when the internal combustion engine E is in a starting state, when activation of starting is within a short time after temporary halting such as an idling stop, i. e. when the halt time t is within the prescribed halt time tl, injection of a fuel/air mixture is carried out using high-pressure injection air without exerting control at the time of starting and combustibility is improved. Superior starting performance is therefore ensured, and the starting period for running in stratified combustion can be made faster so as to dramatically improve combustion. [0075]
The discharge section 52g and pipe 68 of the air pump 52 are arranged next to the exhaust side of the cylinder head 3, and the head-side air passage 54b and cover-side air passage 54c are arranged at the exhaust side of the cylinder head 3 and at the exhaust side of the head cover 4 respectively. As a result, the air passages 54a, 54b, and 54c of the air passage system 54 guiding compressed air discharged from the air pump 52 are arranged at the exhaust side of the cylinder head 3 and the exhaust
side of the head cover 4 which are at a comparatively high temperature compared to the intake side for exhaust gas flowing into the exhaust port 10. When compressed air that is compressed by the air pump 52 so as to rise in temperature flows through the air passages 54a, 54b and 54c, falls in the temperature of the compressed air are suppressed, and it is possible to maintain the temperature of the compressed air. [0076]
As a result, when compressed air flows through the air passage system 54, the occurrence of condensation due to contact with passage walls that are at a lower temperature than the temperature of the compressed air is prevented or suppressed, and the temperature of the injection air within the air chamber 37 can be kept relatively high. The vaporization of fuel at the time of starting is therefore promoted and starting performance is also improved in this respect. [0077]
The whole of the pump cover 52b and the discharge section 52g is positioned further to the side of the connecting surface 3d of the cylinder 2 of the cylinder 3, the uppermost part of the pump chamber 52e is positioned substantially above the connecting surface 3d, and the whole of the air chamber 37 is positioned further towards the air pump 52 than the fuel chamber 36. As a result, the air passages 54a, 54b and 54c reaching the air chamber 37 from the discharge section 52g of the air passage system 54 can be made small and can be arranged collectively at and close to the exhaust side of the cylinder head 3 where the exhaust port 10 is formed. The effect of retaining heat in the compressed air at the air passages 54a, 54b and 54c reaching the air chamber 37 from the air pump 52 of the air passage system 54 can therefore be improved. As a result, this contributes to keeping the temperature of the injection air comparatively high, vaporizing of fuel during starting is promoted, and starting performance is improved. [0078]
By providing an orifice 70 constituting a high-pressure maintaining structure for temporarily keeping the pressure of the injection air at a pressure higher than the set air pressure PA at least until where timing overlaps with the injection start timing of the fuel/air injection valve 30 at the air passage system 54, fuel is injected together with injection air of a pressure higher than the set pressure PA at the injection timing TM and atomizing of fuel within the combustion chamber 8 is therefore promoted. [0079] As a result, when the discharge timing TM during starting is set to the compression
stroke, atomizing of fuel within the combustion chamber is further promoted, and the
starting performance is improved accordingly.
[0080]
Following is a description of the embodiment with a modified configuration of part
of the configuration of the embodiment mentioned above. In the above embodiment, the
timing of switching the injection timing TM from the intake stroke to the compression
stroke is decided based on the engine rotational speed Ne. However, as shown in FIG.
11, this may also be decided based on an injection number Ni of the fuel/air injection
valve 30 rather than on the engine rotational speed Ne.
[0081]
In a flowchart showing a control routine for control during starting of FIG. 11,
processing of step S3 and step S12 of the flowchart of FIG. 9 are replaced with a
process of step S23 and step S32, with other aspects of the processing being the same
as for the flowchart of FIG. 9.
[0082]
Specifically, in step S23, a count for an injection frequency Ni of the fuel/air
injection valve 30 is started from when the ignition circuit enters an operating state.
In step S32, a determination is made as to whether or not Ni is less than or equal
to a prescribed injection number Nil. The prescribed injection frequency Nil is the
frequency of injection Ni corresponding to when the pressure of the injection air
within the air chamber 37 reaches the basic pressure PA0 and may be a plurality of
prescribed numbers such as, for example, 4 to 10, set in advance based on
experimentation etc.
[0083]
When the determination of step S32 is negative, i.e. when it is determined that the
pressure of the injection air has not reached the basic air pressure PA0, step S13
is proceeded to, and the injection timing TM of the fuel/air injection valve 30 is
only set for the intake stroke. Further, when the determination of step S12 is
affirmative, the pressure of the injection air is the basic pressure PA0 or more that
is capable of injection of the fuel/air mixture on the compression stroke. Step S14
is then proceeded to, and the injection timing TM of the fuel/air injection valve
30 is switched over from the intake stroke to the compression stroke, so as to be
set to the compression stroke.
[0084]
Injection frequency detecting means for detecting the frequency of injection Ni is
configured from part of the ECU 80 executing the processing in step S23, and the
injection frequency detecting means also constitutes the engine state detecting
means.
[0085]
According to the internal combustion engine equipped with the injection frequency
detecting means, the injection timing TM is changed over from the intake stroke to
the compression stroke when the pressure of the injection air reaches the basic air
pressure based on detection results of the injection frequency detecting means
without using a pressure sensor for detecting pressure of the injection air so that
fuel atomizing is carried out using high-pressure injection air. This gives the same
results as for the embodiment where whether or not the basic pressure PAO is reached
is determined based on the engine rotational speed Ne.
[0086]
The starting sensor 84 may also start calculating timing during starting using the
on or off state of a starting switch rather than the rotational speed sensor 81 or
a configuration using a timer where time runs out after a prescribed period of time
has elapsed may also be adopted. Further, a recoil starter may also be used as starting
means.
[0087]
In the above embodiment, the injection timing TM of the fuel/air injection valve 30
during high-speed or high-load running of the engine E is set only to the intake stroke
but may'also be set to the intake stroke and the compression stroke respectively.
In this case, the fuel amount corresponding tot he running state is provided to the
combustion chamber 8 separated between the intake stroke and the compression stroke.
[0088]
In internal combustion engine may also be a multi-cylinder internal combustion engine.
Further, the internal combustion engine may be mounted on vehicles other than
motorcycles, and in addition to motorcycles, may also be used as an outboard motor
or as other equipment.
[Description of the Numerals]
1 crankcase, 2 cylinder, 3 cylinder head, 4 head cover, 5 crankshaft, 6 piston, 7 connecting rod, 8 combustion chamber, 9 intake port, 10 exhaust port, 11 intake valve, 12 exhaust valve, 14 sparkplug, 15 intake pipe, 16 valve assembly, 17 camshaft, 18i, 18e cam
I9i, 19e support shaft, 20i, 20e cam follower, 21 i, 21e rocker shaft, 22i, 22e rocker arm, 23i, 23e rod, 24, 25 sprockets, 26 timing chain, 27 valve spring, 28 cooling water pump, 30 fuel/air mixture injection valve, 31 fuel injection valve, 32 air injection valve, 33 to 35 seals, 36 fuel chamber, 37 air chamber, 40 fuel supply system, 41 fuel tank, 42 fuel pump, 43 fuel pressure regulator, 44 fuel passage system, 45 pipe, 46 fitting, 47 return fuel passage, 50 air supply system, 51 air cleaner, 52 air pump, 53 air pressure regulator, 54 air passage system, 55 rotating shaft, 56, 57 sprocket, 58
transmission chain, 59 sliding piece, 60 fitting,
61, 62 seals, 63 air introduction chamber, 64 return air chamber, 65 air
passage, 66 fitting
67 return air passage, 68 passage, 69 pin, 70 orifice, 80 ECU
81 rotational speed sensor, 82 load sensor, 83 top dead center sensor, 84
starting sensor,
85 cooling water temperature sensor, 86 ignition switch, 87 switch E, LI
cylinder shaft, L2 center line of rotation, D cylinder axis direction, H plane,
PA set air pressure, PAO basic air pressure, PF set fuel pressure, NE engine
rotational speed, Nel prescribed engine rotational speed, Ft, Fs flags
t halt time, tl prescribed halt time, Ni injection frequency, Nil
prescribed injection frequency, TM, TF injection timing, TA discharge timing, Ti
ignition timing

[Claims]
A cylinder injection type internal combustion engine, having a fuel/air injection valve for directly injecting a fuel/air mixture of fuel and injection air into a combustion chamber, an air pump driven by the power of a crankshaft for discharging compressed air constituting the injection air, and control means for setting injection timing of the fuel/air injection valve, comprising: engine state detecting means for detecting an engine state of the internal combustion engine, wherein the control means sets the injection timing to the compression stroke of the internal combustion engine according to the engine state detected by the engine state detecting means, and when starting up of the internal combustion engine is detected by the engine state detecting means, the injection timing is set to the intake stroke of the. internal combustion engine and control during starting is executed. [Claim 2] The cylinder injection type internal combustion engine as disclosed in claim 1, wherein the engine state detecting means comprises rotational speed detecting means for detecting rotational speed of the engine, so that when the pressure of the injection air is detected to have reached a prescribed engine rotating speed corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the rotational speed detecting means, during starting control, the control-means switches over the injection timing from the intake stroke to the compression stroke.
[Claim 3] The cylinder injection type internal combustion engine as disclosed in claim 1, wherein the engine state detecting means comprises injection frequency detecting means for detecting injection frequency of the fuel/air injection valve, so that when the pressure of the injection air is detected to have reached a prescribed injection frequency corresponding to reaching of a basic air pressure where injection of an air mixture is possible in the compression stroke by the injection frequency detecting means, during starting control, the control means switches over the injection timing from the intake stroke to the compression stroke.
[Claim 4] The.cylinder injection type internal combustion engine as disclosed in claim 1, wherein the engine state detecting means comprises time detecting means for detecting a time of halting the internal combustion engine, so that when the halt time detected by the time detecting means is within a prescribed halt time corresponding to a state where pressure of the injection air is greater than a basic air pressure where injection of the air mixture is possible in the compression stroke
when starting of the internal combustion engine is detected by the engine state detecting means, the control means sets the injection timing to the compression stroke, and when the halt time exceeds the prescribed halt time, control during starting is executed.
5. A cylinder injection type internal combustion engine substantially as hereinbefore described with reference to the accompanying drawings.

Documents:

746-del-2004-abstract.pdf

746-del-2004-claims cancelled.pdf

746-del-2004-claims.pdf

746-del-2004-correspondence-others.pdf

746-del-2004-correspondence-po.pdf

746-del-2004-description (complete).pdf

746-del-2004-drawings.pdf

746-del-2004-form-1.pdf

746-del-2004-form-19.pdf

746-del-2004-form-2.pdf

746-del-2004-form-3.pdf

746-del-2004-form-5.pdf

746-del-2004-gpa.pdf

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Patent Number

217748

Indian Patent Application Number

746/DEL/2004

PG Journal Number

34/2008

Publication Date

22-Aug-2008

Grant Date

28-Mar-2008

Date of Filing

19-Apr-2004

Name of Patentee

HONDA MOTOR CO., LTD.

Applicant Address

1-1, MINAMIAOYAM 2-CHOME, MINATO-KU, TOKYO, JAPAN.

Inventors:

#	Inventor's Name	Inventor's Address
1	MAMORU URAKI	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYYSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
2	TSUYOSHI TAKIZAWA	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYYSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
3	MASATOSHI SUZUKI	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYYSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
4	SHUNJI AKAMATSU	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYYSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.

PCT International Classification Number

B62D

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2003-138235	2003-05-16	Japan