Title of Invention

AN ENGINE START CONTROL APPARATUS

Abstract [Object]In an engine start control apparatus for cranking an engine with a starter motor to start the engine and automatically de-energizing the starter motor upon completion of the start of the engine, to start the engine reliably and quickly while preventing unnecessary cranking of the engine after the engine has achieved sustained rotation. [Solving Means] The energization of a starter motor is continued until an engine rotational speed reaches a first reference rotational speed (Nref3). The starter motor is de-energized when the engine rotational speed reaches the first reference rotational speed. The starter motor is re-energized when the engine rotational speed drops to a second reference rotational speed (Nref2) which is lower than the first reference rotational speed.
Full Text [See Section 10; rule 13]
"AN ENGINE START CONTROL APPARATUS"
HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan, 1 1, Minamiaoyama 2-chome, Minato-Ku, Tokyo, Japan,
The following specification particularly describes the invention and the manner in which it is to be performed*.


The present invention relates to an engine start control apparatus.
[Detailed Description of the Invention]
The present invention relates to an engine start control apparatus for cranking an engine with a starter motor to start the engine, and more particularly to an engine start control apparatus suitable for use in a system where the crankshaft of an engine and the rotating shaft of a starter motor are directly connected to each other. [0002]
[Prior_ar_t3
Conventional engine start control apparatus having a starter motor is operated by energizing the starter
2

motor to crank the engine while a starter switch is being turned on by the user. The user turns off the starter switch by intuitively determining when the engine is started from the pointer of an engine tachometer or the sound of the engine upon its start. If the engine is not started when the user turns off the starter switch, then the user turns on the starter switch again to try restarting the engine.
[0003]
There is disclosed in Japanese Patent Laid-open No. Hei 5-149221/ etc. an automatic engine stop/start system which automatically stops an engine when a motor vehicle is stopped in order to reduce exhaust gases and fuel consumption while the engine is idling and automatically starts a starter motor to restart the engine when a starting action such as moving a throttle grip from the automatically stopped state is detected.
[0004]
[Problems to be Solved by the Invention]
A system in which an engine is automatically restarted, such as a motor vehicle incorporating the above automatic engine stop/start system, needs to detect when the start of the engine is completed and automatically de-energize the starter motor.
3

[0005]
In a general starting mechanism which applies the rotational power of a starter motor through speed reduction gears to the crankshaft of an engine, there is a relatively large difference between the cranking rotational speed of the engine when the engine is cranked by the starter motor and the idling rotational speed of the engine. After the engine has started, since the engine rotational speed rises, it is relatively easy to detect when the start of the engine is completed based on the engine rotational speed.
[0006]
However, in a starting mechanism which directly connects the crankshaft of an engine and the rotating shaft of a starter motor to each other, the cranking rotational speed of the engine when the engine is cranked by the starter motor increases, reducing the difference between the cranking rotational speed and the idling rotational speed of the engine. Therefore, if the completion of the start of the engine is determined and the starter motor is automatically de-energized based on the engine rotational speed, then the cranking may be ended though the engine is not fully started or, conversely, the cranking may continue though the start of
4

the engine is completed.
[0007]
The above phenomenon also occurs similarly when the user turns on the starter switch to crank the engine. The user may turn off the starter switch though the engine is not fully started or, conversely, the user may continuously turn off the starter switch though the start of the engine is completed.
[0008]
It is an object of the present invention to provide an engine start control apparatus which will solve the conventional problems described above, and which accurately recognizes a timing to stop a starter motor and automatically stops the starter motor.
[0009]
[Means for Solving the Problems]
To achieve the above object, there is provided in accordance with the present invention an engine start control apparatus for cranking an engine with a starter motor to start the engine and automatically de-energizing the starter motor upon completion of the start of the engine, wherein the starter motor is continuously energized until the rotational speed of the engine reaches a first reference rotational speed, the starter
5

motor is de-energized when the rotational speed of the engine reaches the first" reference rotational speed, and the starter motor" is re-energized when the rotational speed of the engine drops to a second reference rotational speed which is lower than the first reference rotational speed. [0010]
According to the above features, when an engine rotational speed is detected at which the engine is highly likely to achieve sustained rotation, the starter motor is automatically stopped. Therefore, unnecessary cranking is prevented after the engine has achieved sustained rotation. When the engine rotational speed is lowered subsequently, the starter motor is immediately re-energized. Consequently, even if the engine has not achieved sustained rotation, the starter motor is automatically restarted before the engine stops, making it possible for the engine to quickly achieve sustained rotation. [0011] [Mode for Carrying out the Invention]
The present invention will be described in detail below with reference to the drawings.


[Brief Description of the Drawings] [Fig. 1]
Fig. l is a side elevational view of a scooter-type motorcycle incorporating an engine start control apparatus according to the present invention; [Fig. 2]
Fig. 2 is a cross - sectional view of swing unit shown in FIG. 1 which is taken along a crankshaft; [Fig. 3]
Fig. 3 is an enlarged view of a portion of the swing unit shown in FIG. 2; [Fig. 4]
Fig. 4 is a block diagram of a control system of a starter doubling as a generator; [Fig. 5]
Fig. 5 is a block diagram of major components of an
7

ECU shown in FIG. 4; [Fig. 6]
Fig. 6 is a flowchart of an engine start control process; [Fig. 7]
Fig. 7 is a timing chart of the engine start control process; [Fig. 8]
Fig. 8 is a flowchart of a processing sequence of an output control apparatus; [Fig. 9]
Fig. 9 is a diagram showing the timing of currents flowing through the phases of stator coils and output signals from rotor angle sensors in an ACG energization control process; [Fig. 10]
Fig. 10 is a table of energization duty ratios that are set using an engine rotational speed as a parameter; [Fig. 11]
Fig. 11 is a flowchart of a swingback control process; and
[Fig. 12{a) through 12(c)]
Fig. 12 (a) through 12 (c) are diagram illustrative of the swingback control process.
8

FIG, 1 is a side eleventionnl view of a scooter-type mrtorcycle
incorporating an engine start control apparatus according to the present invention. The motor vehicle also has an automatic engine stop/start function to automatically stop an engine when the motor vehicle is stopped, and automatically energize a starter motor to restart the engine when a starting action such as opening a throttle grip or turning on a starter switch is made.
[0012]
A front vehicle body portion and a rear vehicle body portion are interconnected by a low floor 4, and a vehicle body frame that serves as the skeleton of the vehicle body generally comprises a down tube 6 and a main pipe 7. A fuel tank and a storage box (both not shown) are supported by the main pipe 7, and a seat 8 is disposed upwardly of the fuel tank and the storage box.
[0013]
On the front vehicle body portion, there is a handle 11 pivotally supported on a steering head 5 upwardly thereof. A front fork 12 extends downwardly from the steering head 5, and a front wheel FW is rotatably supported on the lower end of the front fork 12. The handle 11 has an upper portion covered with a handle cover 13 doubling as an instrument panel. The main pipe 7 has a downwardly extending portion with a bracket 15


projecting from its lower end. A hanger bracket 18 of a swing unit 2 is swingably coupled to the bracket 15 by a link 16.
[0014]
A single-cylinder four-cycle engine E is mounted on a front portion of the swing unit 2. A belt-type continuously variable transmission 10 extends rearwardly from the engine E, and a rear wheel RW is rotatably supported on a speed reducer mechanism 9 that is mounted on a rear portion of the belt-type continuously variable transmission 10 by a centrifugal clutch. A rear cushion 3 is interposed between an upper end of the speed reducer mechanism 9 and an upper bend of the main pipe 7. A carburetor 17 connected to an intake pipe 19 extending from the engine E and an air cleaner 14 coupled to the carburetor 17 are disposed on a front portion of the swing unit 2.
[0015]
FIG. 2 is a cross-sectional view of the swing unit 2 taken along a crankshaft 2 01, and FIG. 3 is an enlarged view of a portion of the swing unit 2 shown in FIG. 2. Those reference characters which are identical to those shown above represent identical or equivalent parts.
[0016]
10

The swing unit 2 is covered with a crankcase 202 comprising left and right crankcaseS 202L, 202R that are combined with each other. The crankshaft 201 is rotatably supported by bearings 208, 209 that are fixed to the crankcase 202R. A connecting rod (not shown) is connected to the crankshaft 201 by a crankpin 213. [0017]
The left crankcase 202L doubles as a belt-type continuously variable transmission case which houses a belt drive pulley 210 rotatably mounted on a crankshaft 201 extending into the left crankcase 202L. The belt drive pulley 210 comprises a fixed pulley member 210L and a movable pulley member 210R. The fixed pulley member 210L is fixed to the left end of the crankshaft 201 by a boss 211, and the movable pulley member 210R is splined to the crankshaft 201 on the right side of the fixed pulley member 210L for movement toward and away from the fixed pulley member 210L. A V-belt 212 engages between the fixed pulley member 210L and the movable pulley member 210R. [0018]
A cam plate 215 is fixed to the crankshaft 201 on the right side of the movable pulley member 210R. A slide piece 215a disposed on the outer circumferential end of


the cam plate 215 is held in slidable engagement with a cam plate slide boss 210Ra disposed on the outer circumferential end of the movable pulley member 210R and extending in the axial direction thereof. The cam plate 215 has a tapered surface extending near its outer circumferential end and inclined toward the movable pulley member 210R, and a dry weight pole 216 is accommodated in a space between the tapered surface and the movable pulley member 210R.
[0019]
When the rotational speed of the crankshaft 201 increases, the dry weight pole 216 disposed between and rotating with the movable pulley member 210R and the cam plate 215 moves in a centrifugal direction under centrifugal forces, pushing the movable pulley member 210R leftward toward the fixed pulley member 210L. As a result, the V-belt 212 sandwiched between the pulley members 210L, 210R moves in a centrifugal direction, increasing the diameter of the engaging portion of the V-belt 212.
[0020]
A driven pulley {not shown) associated with the belt drive pulley 210 is disposed in the rear vehicle body portion, and the V-belt 212 is trained around the


driven pulley. The belt transmission mechanism thus constructed automatically adjusts the power from the engine E and transmits the adjusted power to the centrifugal clutch, causing the speed reducer mechanism 9, etc. to drive the rear wheel RW.
[0021]
A starter generator (ACG starter) 1 which comprises a combination of a starter motor and an AC generator is disposed in the right crankcase 2 02R. The ACG starter 1 has an outer rotor 6 0 fastened to a tapered tip end portion of the crankshaft 201 by a screw 253.
[0022]
A stator 50 disposed in the outer rotor 60 is fastened to the crankcase 202 by a bolt 279. A fan 280 is fixed to the outer rotor 60 by a bolt 246. A radiator 282 is disposed adjacent to the fan 2 80 and covered with a fan cover 281.
[0023]
As shown at an enlarged scale in FIG. 3, a sensor case 28 is fitted in the stator 50. The sensor case 28 houses therein rotor angle sensors {magnetic pole sensors) 29 and a pulse sensor {ignition pulser) 30 which are disposed at equal intervals along the outer circumferential surface of a boss 60a of the outer rotor


60. The rotor angle sensors 29 serve to control energization of the stator coils of the ACG starter 1, and are associated respectively with U, V, and W phases of the ACG starter 1. The ignition pulser 30 serves to control ignition of the engine, and comprises only one ignition pulser. Each of the rotor angle sensors 29 and the ignition pulser 30 may comprise a Hall IC or a magnetoresistor (MR).
[0024]
The rotor angle sensors 29 and the ignition pulser 30 have leads connected to a board 31 to which a wire harness 32 is connected. Over the boss 60a of the outer rotor 60, there is fitted a magnet ring 33 which is magnetized in two zones for applying magnetic actions respectively to the rotor angle sensors 29 and the ignition pulser 30.
[0025]
One of the magnetized zones of the magnet ring 33 which corresponds to the rotor angle sensors 29 has N and S poles arranged alternately at 30 intervals in the circumferential direction in association with the magnetic poles of the stator 50. The other magnetized zone of the magnet ring 3 3 which corresponds to the ignition pulser 30 has a single magnetized region

extending in an angular range over 15° through 40 in the circumferential direction.
[0026]
The ACG starter 1 functions as a starter motor (synchronous motor) when the engine is to be started. The ACG starter 1 is energized by a current supplied from a battery to rotate the crankshaft 201 to start the engine. After the engine is started, the ACG starter 1 functions as a synchronous generator to generate a current which is supplied to the battery charge the same and to various electric devices.
[0027]
Referring back to FIG. 2, a sprocket 231 is fixedly mounted on the crankshaft 201 between the ACG starter 1 and the bearing 209. A chain is trained around the sprocket 231 for driving camshaft (not shown) from the crankshaft 201. The sprocket 231 is integral with a gear 232 for transmitting power to a pump which circulates lubricating oil.
[0028]
FIG. 4 is a block diagram of an electric system including the ACG starter 1. An ECU 3 includes a three-phase full-wave rectification bridge circuit 300 for the full-wave rectification of three-phase alternating

15

currents that are generated by the power generating function of the ACG starter 1, and a regulator 100 for limiting the output from the three-phase full-wave rectification bridge circuit 300 to a predetermined regulating voltage (regulator operating voltage of 14.5 V, for example). [0029]
The ECU 3 also includes a start controller 500 for making it possible to start the engine reliably while preventing excessive cranking, a power generation controller 400 for increasing the arnount of generated power when the engine rotational speed is in a predetermined low rotational speed tange, and a swingback controller 700 for reversing the crankshaft to a given position immediately after the engine is stopped thereby to increase the starting ability of the engine in a next starting cycle. [0030]
To the ECU 3, there is connected to an ignition coil 21 whose secondary coil is connected to an ignition plug 22. To the ECU 3, there also Connected a throttle sensor 23, a fuel sensor 24, a seat switch 25, an idle switch 26, a coolant temperature sensor 27, the rotor angle sensors 29, and the ignition Bulser 30, which apply


detected signals to the ECU 3.
[0031]
To the ECU 3, there are further connected a starter relay 34, a starter switch 35, stop switches 36, 37, a standby indicator 38, a fuel indicator 39, a speed sensor 40, an auto-by starter 41, and a headlight 42. A dimmer switch 43 is connected to the headlight 42.
[0032]
A current is supplied from a battery 2 to the above various components via a main fuse 44 and a main switch 45. The battery 2 is directly connected to the ECU 3 by the starter relay 34, and is also connected to the ECU 3 via the main fuse 44, not via the main switch 45.
[0033]
Operation of the start controller 500, the power generation controller 4 00, and the swingback controller 700 of the ECU 3 will be described below with reference to a functional block diagram shown in FIG. 5.
[0034]
The three-phase full-wave rectification bridge circuit 300 comprises three sets of two series-connected FETs which are connected parallel to each other, and is controlled based on an output from a driver 80.
[0035]


In the start controller 500, an engine rotational speed determining unit 52 determines an engine rotational speed based on a detected signal from the ignition pulser 30 and a frequency signal of a generated voltage, and an engine start determining unit 51 controls the function of the ACG starter 1 as a starter motor based on the state of the starter switch 35, a throttle opening, and the engine rotational speed, etc. [0036]
Operation of the start controller 500 will be described below with reference to a flowchart shown in FIG. 6 and a timing chart shown in FIG. 7. Various reference values, timers, and flags used in the flowchart are defined as follows:
(1) Start failure rotational speed Nref1:
A rotational speed which the engine rotational speed should naturally reach if the ACG starter 1 and the Sft^ind da n&t suffer a failure when the ACC Otartor i is energized.
(2) Restart rotational speed Nref2:
An engine rotational speed at which the ACG starter 1 that has temporarily been stopped is restarted.
(3) Start stop rotational speed Nref3:
An engine rotational speed at which the ACG starter


1 is temporarily de-energized.
(4) Sustained rotational speed Nref4:
An engine rotational speed which is reached when the engine achieves sustained rotation.
(5) Start completion flag Frun:
This flag is set when the sustained rotation of the engine continues for a given period of time and the engine does not need to be cranked by the ACG starter 1, i.e., when the start of the engine is completed.
(6) Start stop flag Fstop:
This flag is set when a state short of the start failure rotational speed Nrefl has continued for a given period of time.
(7) Temporary de-energization flag Foff:
This flag is set for a period of time in which the starter motor is temporarily de-energized after the engine rotational speed has reached the start stop rotational speed Nref3.
(8) First timer Tml:
This timer measures a continuous time in which the engine rotational speed has not reached the start failure rotational speed Nrefl.
(9) Second timer Tm2:
This timer measures a continuous time in which the


engine rotational speed has exceeded the sustained rotational speed Nref4.
(10) Start stop reference value Tstop:
This is a reference value for determining an engine start failure based on the count of the timer Tml. The start stop flag Fstop is set when the count of the timer Tml reaches the start stop reference value Tstop.
(11) Start completion reference value Trun:
This is a reference value for determining a full
start of the engine based on the count of the timer Tm2. The start completion flag Frun is set when the count of the timer Tm2 reaches the start completion reference value Trun.
[0037]
An engine start control process according to the present embodiment is repeatedly carried out as an interrupt routine in a given cyclic period by the engine start determining unit 51.
[0038]
If the starter switch 35 is detected as being turned on or a given starting action is detected in step S10 shown in FIG. 6, the engine start determining unit 51 determines whether the starter switch 35 has been detected as being turned on or not in step Sll in a


preceding cycle. If not detected as being turned on in the previous cycle, then the engine start determining unit 51 performs an initializing process in step S12. [0039]
In step S12, the engine start determining unit 51 resets the temporary de-energization flag Foff which is set for temporarily de-energizing tfte ACG starter 1, the start stop flag Fstop which is set for forcibly stopping the start of the engine because the ACG starter 1 fails to crank the engine sufficiently, tfte first timer Tml which measures a continuous time in which the ACG starter 1 fails to crank the engine sufficiently, and the second timer Tm2 which measures a continuous time in which the engine rotational speed has exceeded the sustained rotational speed Nref4. [0040]
In step S13, the engine start determining unit 51 refers to the temporary de-energization flag Foff. Since the temporary de-energization flag foff is initially off, control goes to step S14. In step Sl4, the engine start determining unit 51 refers to the start completion flag Frun which is set when the start of the engine is completed. Since the start completion flag Frun is initially off, control goes to step S15. In step S15, a
21

drive current is supplied to the ACG starter 1 to enable the ACG starter 1 to crank the engine (at a time to in FIG. 7).
[0041]
In step S16, the engine start determining unit 51 compares the engine rotational speed Ne with the start failure rotational speed Nrefl. If the engine rotational speed Ne is lower than the start failure rotational speed Nrefl as at a time tl in FIG. 7, then the engine start determining unit 51 increments the first timer Tml in step S17. In step S18, the engine start determining unit 51 compares the count of the first timer Tml with the start stop reference value Tstop. Since the count of the first timer Tml is initially lower than the start stop reference value Tstop, the present cycle is put to an end.
[0042]
In next and subsequent cycles, control goes from step Sll to steps S13, S14, S15, S16, while skipping step S12. Control then goes to step S17 to continuously increment the first timer Tml until the engine rotational speed Ne is determined as being higher than the start failure rotational speed Nrefl in step S16.
[0043]
Thereafter, if the engine rotational speed Ne is


continuously lower than the start failure rotational speed Nrefl until a time t6 and the count of the first timer Tml is determined as exceeding the start stop reference value Tstop in step S18, as with a case 1 in FIG. 7, then the start stop flag Fstop is set in step S19. In next and subsequent cycles, therefore, controls goes from step S13 to step S20, turning off the ACG starter 1. Consequently, the cranking action is interrupted until the starter switch 35 is turned on again or a certain starting action is made. [0044]
Before the count of the first timer Tml is determined as exceeding the start stop reference value Tstop in step S18, if the engine rotational speed Ne exceeds the start failure rotational speed Nrefl at a time t2 as determined in step S16, control proceeds to step S21. In step S21, the first timer Tml is reset and the start stop flag Fstop is reset. [0045]
In step S22, the engine start determining unit 51 compares the engine rotational speeq Ne with the restart rotational speed Nref2. If the engine rotational speed Ne is lower than the restart rotational speed Nref2 as at a time t3, then the engine start determining unit 51 refers

2*r7-2>

to the temporary de-energization flag Foff in step S23. Since the temporary de-energization flag Foff is reset, control goes back to step S16 via steps S25, S27.
[0046]
Thereafter, if the engine rotational speed Ne reaches the restart rotational speed Nref2 at a time t4 as determined in step S22, then the engine start determining unit 51 compares the engine rotational speed Ne with the start stop rotational speed Nref3. Insofar as the engine rotational speed Ne is lower than the start stop rotational speed Nref3, control goes back to step S16 via step S27.
[0047]
Thereafter, if the engine rotational speed Ne reaches the start stop rotational speed Nref3 at a time t7 as determined in step S25, then the ACG starter 1 is turned off and the temporary de-energization flag Foff is set in step S26. In step s27, the engine start determining unit 51 compares the engine rotational speed Ne with the sustained rotational speed Nref4. Because the engine rotational speed Ne is initially lower than the sustained rotational speed Nref4, control returns to step S16.
[0048]


Subsequently, the processing from step S16 is repeated. If the engine is not fully started, then the engine rotational speed Ne is gradually lowered immediately after the ACG starter 1 is stopped at the time t7 (a case 2). If the engine rotational speed Ne drops to the restart rotational speed Nref2 at a time t8 as detected in step S22, then the engine start determining unit 51 refers to the temporary de-energization flag Foff in step S23.
Since the temporary de-energization flag Foff has now been set in step S26, control goes to step S24. In step S2 4, the engine start determining unit 51 restarts the ACG starter 1 and resets the temporary de-energization flag Foff. Therefore, the engine rotational speed Ne begins to increase again at the time t8. [0049]
If the engine achieves sustained rotation {a case 3) and the engine rotational speed Ne reaches the sustained rotational speed Nref4 at a time t9 or tlO as detected in step s27, then the engine start determining unit 51 increments the second timer Tm2 in step S28. In step S29, the engine start determining unit 51 compares the count of the second timer Tm2 with the start completion reference value Trun. If the count of the


second timer Tm2 reaches the start completion reference value Trun, then the engine start determining unit 51 sets the start completion flag Frun in step S30, and the present cycle of the engine start control process is finished.
In the present embodiment, if the engine rotational speed increases to a given rotational speed (Nref3) when the engine is cranked by the ACG starter as the starter motor, the cranking is interrupted and the engine rotational speed is monitored. If the engine rotational speed thereafter drops to a given rotational speed (Nref2), the ACG starter is restarted to crank the engine. Therefore, the engine can reliably be started while being prevented from being cranked excessively.
[0050]
Referring back to FIG. 5, the power generation controller 400 has, in addition to its normal function to control the amount of generated power, a function to energize the stator coils of the respective phases of the ACG starter 1 with the battery 2 at a retarded angle to increase the amount of generated power (hereinafter referred to as "ACG energization control").
[0051]
The energization of the stator coils at a retarded

angle refers to energizing the stator coils with a delay which corresponds to a predetermined electric angle from a detected signal representing a change in the magnetic poles of the magnetic ring 33 as detected by the rotor angle sensors 29. In order to prevent the engine rotational speed from becoming unstable due to a rapid change in the engine load which is caused when the regulator 100 is operated in a low rotational speed range, the output voltage (battery voltage) of the full-wave rectification bridge circuit 300 is controlled to fall in a predetermined voltage range lower than the regulating voltage. [0052]
In the power generation controller 400, an engine rotational speed determining unit 48 detects an engine rotational speed based on a detected signal from the ignition pulser 30, and supplies an angular retarding command to the driver 80 if the detected engine rotational speed is in a predetermined power generation control range. In response to the angular retarding command, the driver 80 reads a preset energization retarding angle from a retarded angle setting unit 49 to energize the stator coils at the retarded angle. An energization duty ratio is supplied from a duty ratio
27

setting unit 47 to the driver 80. [0053]
The driver 80 detects a magnetic-pole detected signal from the rotor angle sensors 29, i.e., a signal which is turned on each time each of the rotor angle sensors 2 9 detects one of the magnetized poles of the magnetized zone of the magnetic ring 33 which are
associated with the magnetic poles of the outer rotor 60. The driver 80 then outputs a PWM control signal to the FETs of the full-wave rectification bridge circuit 300 with a delay corresponding to the energization retarding angle from a positive-going edge of the signal. [0054]
A battery voltage determining unit 4 6 compares a battery voltage Vb with a control voltage maximum value VMax and a control voltage minimum value VMin which define a voltage control range, and increases or reduces the energization duty ratio set by the duty ratio setting unit 47 based on the compared result to bring the battery voltage Vb into the voltage control range. Specifically, if the battery voltage Vb reaches the control voltage maximum value VMax, the battery voltage determining unit 4 6 reduces the energization duty ratio by a predetermined small value of 1%, for example, and if the battery


voltage Vb falls to the control voltage minimum value VMin, the battery voltage determining unit 46 increases the energization duty ratio by the same small value.
[0055]
FIG. 8 is a flowchart of an operation sequence of the power generation controller 4 00, which is activated after the engine start control process carried by the start controller 500 is ended.
[0056]
In step S41, the power generation controller 400 determines whether the engine rotational speed is present in the power generation control range or not. The power generation control range is set between 1000 rpm and 3 5 00 rpm. If the engine rotational speed is present in the power generation control range, then control goes to step S4 2 in which the power generation controller 400 determines whether a flag FACG indicating that the engine rotational speed is present in the power generation control range is set {= 1) or not. If the flag FACG is not set, control goes to step S43 in which the power generation controller 400 sets the flag FACG. In step S44, the power generation controller 400 sets an energization retarding angle acgagl to a predetermined value ACGAGL. While the predetermined value ACGAGL may be of an


appropriate value, it is equal to an electric angle 60 for example, in the present embodiment. [0057]
In step S45, an energization duty ratio acduty is set to an initial value ACDUTY. While the initial value
ACDUTY may be of an appropriate value, it is set to 40° , for example, in the present embodiment. After steps S43 through S45, control goes to step S46. If the answer to step S42 is affirmative, then control goes to step S47, skipping steps S43 through S4 5. If the engine rotational speed is not present in the power generation control range in step S41, then the power generation controller 400 resets the flag FACG (= 0) in step S46, after which control goes to step s47. [0058]
In step S47, the power generation controller 400 determines whether the flag FACG is set or not in step S47. If the flag FACG is set, then the power generation controller 400 determines whether or not the battery voltage Vb is equal to or higher than the control voltage maximum value VMax in step S48. The control voltage maximum value VMax is set to a value lower than the regulating voltage, e.g., 13.5 volts. If the battery voltage Vb is not equal to or higher than the control


voltage maximum value VMax, then control goes to step S49 in which the power generation controller 400 determines whether or not the battery voltage Vb is equal to or higher than the control voltage minimum value VMin. The control voltage minimum value VMin is set to 13.0 volts, for example.
[0059]
If the battery voltage Vb is not equal to or higher than the control voltage minimum value VMin in step S49, then the power generation controller 400 determines that the battery voltage Vb is in an ACG energization range lower than the regulating voltage of the regulator. Control then goes to step S50 in which the power generation controller 400 performs an ACG energization control process according to the energization retarding angle acgagl and the energization duty ratio acduty.
[0060]
If the battery voltage Vb is equal to or higher than the control voltage maximum value VMax in step S48, then control goes to step S51 in which the power generation controller 400 subtracts the energization duty ratio acduty by a small value DDUTY, which is set to 1%, for example. If the battery voltage vb is equal to or higher than the control voltage minimum value VMin in

step S49, then control goes to step S52 in which the power generation controller 400 increases the energization duty ratio acduty by the small value DDUTY. After steps S51, S52, control goes to step S50. [0061]
The small value DDUTY to be added to increase the energization duty ratio acduty and the small value DDUTY to be subtracted to reduce the energization duty ratio acduty may not necessarily be identical to each other. The small value DDUTY may be varied in proportion to the difference between the control voltage maximum value VMax or the control voltage minimum value VMin and the present value of the battery voltage. [0062]
If the flag FACG is not set in step S47, then since the engine rotational speed is not present in the power generation control range, control goes to step S53 in which the power generation controller 400 stops the ACG energization control process. [0063]
FIG. 9 is a diagram showing the timing of currents flowing through the phases (phase currents) of the stator coils and output signals from the rotor angle sensors 29 in the ACG energization control process. In a normal mode

in which no retarded-angle energization control process is carried out, currents are supplied to the U, V, W phases of the stator coils in response to positive and negative (NS) changes of the output signals from the rotor angle sensors 29. When the retarded-angle energization control process is carried out, currents are supplied to the U, V, W phases of the stator coils at a
predetermined retarded angle d (= 60 ) from positive and negative (NS) changes of the output signals from the rotor angle sensors 29.
[0064]
In FIG. 9, an energization angle T according to duty ratio chopping is 18 0 . However, the energization angle T may be determined within 180 by an energization duty ratio that is supplied from the duty ratio setting unit 47 to the driver 80.
[0065]
FIG. 10 is a table of energization duty ratios that are set using the engine rotational speed Ne, i.e., the rotational speed of the ACG starter 1, as a parameter. An engine rotational speed is detected, and an energization duty ratio depending on the detected engine rotational speed is determined by referring to FIG. 8.
[0066]


With the power generation control according to the present embodiment, the amount of generated power can stably be increased without operating an ordinary voltage regulator in a low rotational speed range. Therefore, as when the engine is idling, variations in the engine load can be reduced to minimize variations in the engine rotational speed, thus allowing the engine to idle stably.
[0067]
Referring back to FIG. 5, immediately after the engine has stopped, the swingback controller 700 reverses the crankshaft to return to a predetermined position in order to reduce the cranking torque required to start the engine for thereby increasing the starting ability of the engine.
[0068]
A stage determining unit 73 divides one revolution of the crankshaft 201 into 36 stages ranging from stage #0 through stage #35 based on the output signals from the rotor angle sensors 29, and determines a present stage using the detected timing of a pulse signal generated by the ignition pulser 30 as a reference stage (stage #0).
[0069]
A stage passage time detector 74 detects a passage time Atn of a new stage based on a period of time from


the time when the stage determining unit 7 3 determines the new stage until it determines a next stage. A reverse controller 75 generates a reverse drive command based on the stage determined by the stage determining unit 7 3 and
the passage time Atn detected by the stage passage time detector 74.
[0070]
Based on the stage determined by the stage determining unit 73, a duty ratio setting unit 72 dynamically controls the duty ratio of a gate voltage supplied to each of the FETs of the full-wave rectification bridge circuit 3 00. The driver 80 supplies drive pulses of the duty ratio thus set to the respective FETs of the full-wave rectification bridge circuit 300.
[0071]
Operation of the swingback controller 7 00 will be described below with reference to a flowchart shown in FIG. 11 and diagrams illustrative of its operation in FIGS. 12(a) through 12(c). FIG. 12(a) shows the relationship between cranking torques (reverse load) required to reverse the crankshaft 201 and crank angles, the cranking torque sharply increasing immediately prior to a compression top dead center (when the crankshaft is reversed). FIG. 12(b) shows the relationship between


crank angles and stages. FIG. 12(c) shows the manner in which the angular velocity of the crankshaft changes when the crankshaft is reversed.
[0072]
If the engine is stopped as detected in step S61, then the present stage which has already been determined by the stage determining unit 73 is referred to in steps S62, S63. If the present stage is either one of stages #0 through #11, then control goes to step S64. If the present stage is either one of stages #12 through #32, then control goes to step S65. If the present stage is otherwise (i.e., it is either one of stages #33 through #35, then control goes to step S66. In steps S64, S66, the duty ratio setting unit 72 sets the duty ratio of drive pulses to 70%. In step S65, the duty ratio setting unit 72 sets the duty ratio of drive pulses to 80%.
[0073]
The dynamic control of the duty ratio is carried out to sufficiently lower the angular velocity of the crankshaft 201 when it is reversed, before (the crankshaft 201 is reversed) an angle corresponding to a compression top dead center where the cranking torque increases, and also to quickly reverse the crankshaft 201 at other angles.


[0074]
In step S67, the driver 80 controls the FETs of the full-wave rectification bridge circuit 300 with the set duty ratio to start energizing the FETs to reverse the crankshaft 201. In step S68, the passage time Atn of stage #n that has been passed is measured by the stage passage time detector 74.
[0075]
In step S69, the reverse controller 75 determines whether the crankshaft 201 has passed stage #0, i.e., in the vicinity of a top dead center, or not. If the crankshaft 2 01 has not passed stage #0, then the reverse controller 75 compares the ratio [Atn/Atn-1] between the passage time Atn of preceding stage #n which has been passed and the passage time Atn-1 of stage #(n-l) which has been passed prior to preceding stage #n with a reference value Rref (4/3 in the present embodiment). If the passage time ratio [Atn/Atn-1] is not in excess of the reference value Rref, then control returns to step S62 to continue the reversed rotation of the crankshaft, with the above various processes being performed concurrent therewith.
[0076]
If the engine stop position, i.e., the reverse


start position, is located on a side of an intermediate position between preceding and next compression top dead centers which is closer to the next compression top dead center, i.e., in an interval from an exhaust top dead center (when the crankshaft is rotated in normal direction) toward the next compression top dead center, as indicated by the curve A in FIG. 12 (c) , then the crankshaft can pass stage #0 (exhaust top dead center) through the ACG starter 1 is reversed at the duty ratio of 7 0%. Therefore, the passage of stage #0 is detected in step S69, and control goes to step S70 which determines whether the crankshaft 2 01 has reached stage #3 2 or not. If the crankshaft 201 has reached stage #32, then the energization of the FETs to reverse the crankshaft is stopped. Thereafter, the crankshaft is further reversed under inertial forces, and then stopped. [0077]
If the reverse start position is located on a side of the intermediate position between the preceding and next compression top dead centers which is closer to the preceding compression top dead center, i.e., in an interval from the preceding compression top dead center (when the crankshaft is rotated in normal direction) toward the exhaust top dead center, as indicated by the


curve B in FIG. 12{C), then since the ACG starter 1 is reversed at the duty ratio of 70%, when the reverse load increases prior to stage #0 (when the crankshaft is reversed), as shown in FIG. 12(a), the angular velocity of the crankshaft 201 sharply drops. If the passage time ratio [Atn/Atn-1] is equal to or greater than 4/3 of the reference value in step S71, then the energization of the FETs to reverse the crankshaft is stopped in step S72. The reversed rotation of the crankshaft is stopped substantially at the same time that the energization is stopped. [0078]
With the swingback control according to the present embodiment, as described above, when the crankshaft is reversed after the engine is stopped, it is monitored whether the crankshaft has passed an angle corresponding to a top dead center or not and whether the angular velocity of the crankshaft has dropped or not. If the crankshaft of it is reversed has passed a top dead center, then the energization of the FETs to reverse the crankshaft is ended immediately thereafter. If the angular velocity of the crankshaft has dropped due to an increase in the reverse load, then the energization of the FETs to reverse the crankshaft is also ended.
39

Therefore, regardless of the reverse start position, it is possible to return the crankshaft to a position before the preceding compression top dead center (when the crankshaft is reversed) and where compression reactive forces are low.
[0079]
With the swingback control according to the present embodiment, furthermore, since the angular velocity of the crankshaft 201 is detected based on the output signals from the rotor angle sensors 29 which detects the rotor angle (i.e., stages) of the ACG starter, it is not necessary to provide a separate sensor for detecting the angle of the crankshaft 201.
[0080]
[Effects of the Invention]
According to the present invention, since the starter motor is automatically stopped when an engine rotational speed which is highly likely to indicate that the engine has achieved sustained rotation is detected, unnecessary cranking after the engine has achieved sustained rotation is prevented. If the engine rotational speed is subsequently lowered because a determination of sustained rotation of the engine based on the engine rotational speed is in error, then the starter motor is

immediately restarted. Consequently, the engine can reliably be started even if it is difficult to determine sustained rotation of the engine based on the engine rotational speed because the cranking rotational speed of the engine cranked by the starter motor and the idling rotational speed of the engine are substantially the same as each other.
[Description of Reference Numerals]
1 "■ starter doubling as generator (ACG starter), 2 ■■■ battery, 3. ■".ECU, 4 ■■■ full-.wave rectifier, 5 ■■■ regulator, 29 ■•■ rotor angle sensor, 30 "" ignition pulser, 50 ■■• stator, 60 ••■ outer rotor, 62 •■■ magnet, 201 -■• crankshaft.


WE CLAIM:
1. An engine start control apparatus for cranking an engine with a
starter motor to start the engine and automatically de-energizing the
starter motor upon completion of the start of the engine, said engine
start control apparatus comprising:
means for continuously energizing the starter motor until the rotational speed of the engine reaches a first reference rotational speed;
means for de-energizing the starter motor when the rotational speed of the engine reaches said first reference rotational speed;
means for de-energizing the starter motor when the rotational speed of the engine drops to a second reference rotational speed which is lower than said first reference rotational speed; and
if the rotational speed of engine is higher than the third reference speed which is higher than the first reference speed for more than predetermined period, starting engine will be completed.
2. An engine start control apparatus as claimed in claim 1, wherein an idling rotational speed of said engine is substantially equal to a cranking rotational speed of the engine when the engine is cranked by said starter motor.
3. An engine start control apparatus as claimed in claim 1 or 2, wherein the start of the engine is completed when the rotational speed of the engine exceeds a third reference rotational speed which is higher than said first reference rotational speed for a predetermined time or more.
-42-

4 An engine start control apparatus as claimed in claim 3, wherein after completion of the start of the engine, a retard control process is carried out to cause an ignition timing to lag behind a reference timing in a low rotational speed range of the engine.
5. An engine start control apparatus substantially as hereinbefore described with reference to the accompanying drawings.

Documents:

1101-mum-2001-abstract.pdf

1101-mum-2001-claims.doc

1101-mum-2001-claims.pdf

1101-mum-2001-correspondence(ipo).pdf

1101-mum-2001-correspondence.pdf

1101-mum-2001-description(granted).doc

1101-mum-2001-description(granted).pdf

1101-mum-2001-drawing.pdf

1101-mum-2001-espana patents of europia.pdf

1101-mum-2001-espana patents of solicitud.pdf

1101-mum-2001-espana patents.pdf

1101-mum-2001-europian patent.pdf

1101-mum-2001-form 1-24-aug-2007.pdf

1101-mum-2001-form 1.pdf

1101-mum-2001-form 13.pdf

1101-mum-2001-form 18.pdf

1101-mum-2001-form 2(cancelled)-20-nov-2001.pdf

1101-mum-2001-form 2(granted).pdf

1101-mum-2001-form 2(title page).pdf

1101-mum-2001-form 3-1-apr-2002.pdf

1101-mum-2001-form 3.pdf

1101-mum-2001-form 5.pdf

1101-mum-2001-official letter-27-apr-2004.pdf

1101-mum-2001-others.pdf

1101-mum-2001-power of authority.pdf

1101-mum-2001-retyped us patent.pdf

1101-mum-2001-us patents.pdf

1101-mum-2001form-2(granted).doc

1101-mum-201-abstract.doc

abstract1.jpg


Patent Number 211339
Indian Patent Application Number 1101/MUM/2001
PG Journal Number 45/2007
Publication Date 09-Nov-2007
Grant Date 26-Oct-2007
Date of Filing 20-Nov-2001
Name of Patentee HONDA GIKEN KOGYO KABUSHIKI KAISHA
Applicant Address 1-1, MINAMIAOYAMA 2-CHOME, MINATO-KU, TOKYO,
Inventors:
# Inventor's Name Inventor's Address
1 OTA ATSUO C/O KABUSHIKI KAISHA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA,
PCT International Classification Number F02P5/15,F02N11/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2000-387255 2000-12-20 Japan