Title of Invention	AN IGNITION APPARATUS FOR AN INTERNAL COMBUSTION ENGINE
Abstract	An ignition apparatus for an engine ignites mixture gas in a combustion chamber of the engine. The ignition apparatus includes an ignition coil, a battery, a switching element, a first condenser, and a reverse flow preventing means. The ignition coil includes a primary coil and a secondary coil. The battery supplies electricity to the primary coil. The switching element controls primary electricity, which passes through the primary coil. The first condenser is arranged to be in parallel with the battery. The first condenser supplies electricity to the primary coil and the switching element, when the battery runs down. The reverse flow preventing means prevents electricity from flowing from the first condenser to the battery.

Title of Invention

AN IGNITION APPARATUS FOR AN INTERNAL COMBUSTION ENGINE

Abstract

An ignition apparatus for an engine ignites mixture gas in a combustion chamber of the engine. The ignition apparatus includes an ignition coil, a battery, a switching element, a first condenser, and a reverse flow preventing means. The ignition coil includes a primary coil and a secondary coil. The battery supplies electricity to the primary coil. The switching element controls primary electricity, which passes through the primary coil. The first condenser is arranged to be in parallel with the battery. The first condenser supplies electricity to the primary coil and the switching element, when the battery runs down. The reverse flow preventing means prevents electricity from flowing from the first condenser to the battery.

Full Text	IGNITION APPARATUS FOR INTERNAL COMBUSTION ENGINE Description The present invention relates to an ignition apparatus for an internal combustion engine, the ignition apparatus igniting mixture gas in a combustion chamber of an internal combustion engine for a motorcycle, an automobile, and the like. Mixture gas is introduced into a combustion chamber of an internal combustion engine, and the mixture gas is ignited with an ignition plug. Here, high voltage for the ignition plug is generated by an ignition coil. That is, electricity passing through a primary coil of the ignition coil is intermitted, so that predetermined low-voltage is generated in the primary coil by self-induction. The low-voltage is boosted by mutual induction between the primary coil and a secondary coil, so that boosted high voltage is applied to the ignition plug via the secondary coil. A voltage boosting system is roughly classified into CDI (Capacitor Discharge Ignition) system and an induction discharge system, i.e., a full-transistor system. The CDI system is a boosting system, in which high-voltage electricity, which is charged in a condenser of the CDI system, is instantaneously discharged into a primary coil, so that predetermined high voltage is generated in a secondary coil. In this system, decrease of ignition energy is small, even when rotation speed of the engine is high. In addition, mixture gas can be ignited with electric charge, which is accumulated in the condenser, even when a battery is completely discharged, i.e., the battery runs out. Therefore, the CDI system is generally applied to an engine, which rotates at high speed, and a small displacement motorcycle, that is, a 2-cycle engine. On the contrary, the induction discharge system is a boosting system, in which primary electricity, which passes through the primary coil, is shut using a switching element of an igniter, so that electricity at predetermined high-voltage is generated in a secondary coil. In this system, a time period, in which spark is generated in an ignition coil, is extended, so that the system can steadily ignite even lean mixture gas. Therefore, the induction discharge system is generally applied to an automobile and a large displacement motorcycle, that is, a 4-cycle engine, to which high fuel efficiency is demanded. In recent years, emission regulations are apt to be intensified with respect to motorcycles. Accordingly, the number of motorcycles with 4-cycle engines, which can easily meet emission regulations, is apt to increase. Particularly, the tendency is remarkable in a small displacement motorcycle, so that an igniter using the induction discharge system is apt to be applied to a small displacement motorcycle in consideration of fuel efficiency. A battery of a motorcycle is small in capacity, accordingly, the battery is apt to run down. When the battery runs down, the primary coil and the igniter cannot be supplied with electricity. Therefore, when an igniter using the induction discharge system is applied to a small displacement motorcycle, a special structure needs to be provided to steadily start an engine when a battery runs down. According to a conventional igniter disclosed in JP-A-2001 -349270, a condenser is connected in parallel with a primary coil, so that electric charge is accumulated in a condenser when an engine is rotated. Thereby, the electric charge, which is accumulated in the condenser, is used for starting the engine, in the case where the battery runs down. A battery-less small displacement motorcycle, which does not have a battery, is used in consideration of reduction of a vehicle body in weight, maintenance free, and a safety measure for prevention of theft of a battery. In this case, an engine is started by kicking, and an alternator supplies a primary coil and an igniter with electricity after the engine is started. However, electricity supplied from the alternator may become unstable depending on rotation speed of the alternator and performance of a regulator, which rectifies alternate current into direct current. Accordingly, in this case, electricity needs to be supplied using a condenser. The condenser in above conventional ignition apparatus is connected with a wiring (line) that connects a battery with a primary coil. Accordingly, when the battery runs down, electricity passes from the condenser not only to a primary coil but also to the battery. The battery acts as a resister, and electric charge, which is accumulated in the condenser, is consumed in the battery. As a result, the primary coil and the igniter may not be supplied with predetermined electricity. In view of the foregoing problems, it is an object of the present invention to produce an ignition apparatus for an internal combustion engine using an induction discharge system, the ignition apparatus being capable of steadily igniting mixture gas, even in starting when a mounted battery runs down, and even when an alternator unstably supplies electricity in a battery less system. According to the present invention, an ignition apparatus for an internal combustion engine ignites mixture gas in a combustion chamber of the internal combustion engine. The ignition apparatus includes an ignition coil, a battery, a switching element, a first condenser, and a reverse flow preventing means. The ignition coil includes a primary coil and a secondary coil. The battery supplies electricity to the primary coil. The switching element controls primary electricity, which passes through the primary coil. The first condenser is arranged to be in parallel with the battery. The first condenser supplies electricity to the primary coil and the switching element when the battery runs down. The reverse flow preventing means prevents electricity from flowing to the battery from the first condenser. The ignition apparatus further includes a first wiring and a second wiring. The first wiring extends from the battery to the primary coil. The second wiring extends from a branch point, which is located at an intermediate point in the first wiring, to the switching element. The first condenser is arranged at the branch point. The first condenser is arranged between the reverse flow preventing means and the primary coil. The first condenser is arranged between the reverse flow preventing means and the switching element. The first condenser has capacitance that is equal to or greater than 1000 μF, and is equal to or less than 7000 μF. The ignition apparatus further includes a condenser accommodating portion that accommodates the first condenser, which is in one piece. The condenser accommodating portion is exposed to outside air The ignition apparatus further includes a controller, a transformer power source, and a second condenser. The controller is arranged on the second wiring. The controller controls the switching element. The transformer power source transforms voltage of the battery. The transformer power source applies the voltage to the controller. The second condenser is connected to a portion between the transformer power source and the controller. The second condenser is capable of supplying electricity to the controller. The second condenser has capacitance that is equal to or greater than 500 μF, and is equal to or less than 1000μF. The reverse flow preventing means is at least one of a diode and a thyristor that is arranged between the branch point and the battery. Alternatively, an ignition apparatus for an internal combustion engine ignites mixture gas in a combustion chamber of the internal combustion engine. The ignition apparatus includes an ignition coil, an alternator, a switching element, a first condenser, and an accessory condenser. The ignition coil includes a primary coil and a secondary coil. The alternator is operated by the internal combustion engine. The alternator supplies electricity to the primary coil. The switching element controls primary electricity, which passes through the primary coil. The first condenser supplies electricity to at least the primary coil and the switching element when electricity supplied from the alternator is unstable. The accessory condenser supplies electricity to an accessory when electricity supplied from the alternator is unstable. The ignition apparatus further includes a fourth wiring and a fifth wiring. The fourth wiring extends from the alternator to the primary coil. The fifth wiring extends from a branch point, which is located at an intermediate point in the fourth wiring, to the switching element. The first condenser is arranged at the branch point. The ignition apparatus further includes a first reverse flow preventing means and a second reverse flow preventing means. The first reverse flow preventing means is arranged between the first condenser and the alternator. The second reverse flow preventing means is arranged between the accessory condenser and the alternator. The ignition apparatus further includes a first accessory and a second accessory. The first condenser supplies electricity to the primary coil, the switching element, and the first accessory. The accessory condenser supplies electricity to the second accessory. The first accessory may be an injector. The second accessory may be a pump. The first condenser supplies electricity to the primary coil and the switching element. The accessory condenser supplies electricity to the first accessory and the second accessory. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: FIG. 1 is a block diagram showing an ignition apparatus for an internal combustion engine according to a first embodiment of the present invention; FIG. 2 is a perspective view showing an igniter according to the first embodiment; FIG. 3 is a graph showing a relationship between rotation speed Ne of an engine and voltage Vth for starting the engine when the engine is started by kicking; FIG. 4 is a block diagram showing an ignition apparatus for an internal combustion engine according to a second embodiment of the present invention; FIG. 5 is a block diagram according to a first variation of the second embodiment; and FIG. 6 is a block diagram according to a second variation. (First Embodiment) An ignition apparatus is applied to an ignition apparatus for an internal combustion engine of a motorcycle with a displacement of 125 cc, in the following description. As shown in FIG. 1, a first wiring 12 extends from a battery 10 to a primary coil 37 of an ignition coil 36. A diode 30 is arranged on the first wiring 12. The diode 30 serves as a reverse flow preventing means. A second wiring 16 branches from a branch point 14 on the downstream side of the diode 30, and extends to a gate of a power transistor 22. The power transistor 22 serves as a switching element. A transformer power source 24 and a CPU 26 are arranged on the second wiring 16. The CPU 26 serves as a controller. A first condenser 20 is connected to the branch point 14. A second condenser 28 is connected between the transformer power source 24 and the CPU 26. A third wiring 18 extends from an alternator 32 to the battery 10. A regulator 33 including a rectifier is arranged on the third wiring 18. A lamp 34 is connected to the regulator 33. The alternator 32 is arranged on the high voltage side with respect to the battery 10. The alternator 32 includes a magnet and a coil. The alternator 32 is operated by the engine, so that the alternator 32 generates alternate current. An ignition coil 36 includes the primary coil 37 and a secondary coil 38. The secondary coil 38 is connected to an ignition plug 39. The primary coil 37 has one end, which is connected to the battery 10, and has the other end, which is connected to a collector of the power transistor 22. Next, an igniter 45, which is located on the low-voltage side of the battery 10, is described in reference to FIGS. 1,2. As shown in FIG. 2, the igniter 45 includes a casing 46, a substrate 48, the first condenser 20, and the like. The casing 46 is formed of resin to be in a box shape. The casing 46 is secured to the inside of a side cowling (not shown) to be exposed to outside air. A condenser accommodating portion 47, which is in a partially cylindrical shape, is integrally formed with the casing 46. The first condenser 20, the second condenser 28, the diode 30, the transformer power source 24, the CPU 26, the power transistor 22, and the like are arranged on the substrate 48. The first condenser 20 in a cylindrical shape is set at 4700 nF in capacitance, so that the first condenser 20 has a relatively large body. The first condenser 20 upwardly protrudes from the substrate 48, and the protruding portion of the first condenser 20 is accommodated in the condenser accommodating portion 47. The diode 30 is arranged such that the anode of the diode 30 is located on the side of the battery 10, so that the diode 30 permits electricity flowing from the battery 10 to the primary coil 37, the first condenser 20, the transformer power source 24, and the like. The diode 30 prohibits electricity from flowing to the battery 10 from the first condenser 20. The first condenser 20 and the transformer power source 24 are connected in parallel with each other on the low-voltage side of the diode 30, and are connected in parallel with the primary coil 37 of the ignition coil 36. The second condenser 28 is set at 1000 μF in capacitance. The power transistor 22, which is connected on the low-voltage side of the CPU 26, is turned ON and OFF by the CPU 26, so that electricity supplied from the battery 10 to the primary coil 37 is turned ON and OFF. Next, an operation of the ignition apparatus is described. A start button (not shown) is operated by a driver, so that the engine is started. In this situation, electricity passes from the battery 10 to the primary coil 37 and the igniter 45. The CPU 26 turns the transistor 22 OFF, and primary electricity is shut, so that high voltage is generated in the secondary coil 38, thereby, the ignition coil 36 ignites mixture gas. The alternator 32 is rotated by the engine after the engine is started, and alternate current generated in the alternator 32 is rectified through the regulator 33. The rectified current is supplied to the primary coil 37, the transformer power source 24, the CPU 26, and the power transistor 22 through the first wiring 12 and the second wiring 16. Generated current is transformed, i.e., is decreased in voltage through the transformer power source 24, so that the transformed current is used for operating the CPU 26. The CPU 26 receives a predetermined signal, so that the CPU 26 performs ON/OFF control with respect to the power transistor 22. The power transistor 22 is turned ON, and the battery 10 and the primary coil 37 are supplied with electricity, so that primary electricity passes through the primary coil 37. The power transistor 22 is turned OFF, and primary electricity is shut, so that the primary coil 37 generates predetermined low-voltage by self-induction. The low-voltage is boosted by mutual induction between the primary coil 37 and the secondary coil 38, so that boosted high voltage is applied to the ignition plug 39 via the secondary coil 38. Alternate current is generated in the alternator 32, and the alternate current is rectified through the regulator 33 to be direct current. The direct current, which is rectified through the regulator 33, is charged in the first condenser 20. Direct current, which is charged in the first condenser 20 as electric charge, is transformed in voltage through the transformer power source 24. The transformed current is charged in the second condenser 28 as electric charge. When the battery 10 runs down, electric charge accumulated in the first condenser 20 is supplied to the primary coil 37, the transformer power source 24, and the like to start the engine. Besides, electric charge accumulated in the second condenser 28 is supplied to the CPU 26. Thereby, the ignition coil 36 generates high voltage, so that the ignition plug 39 ignites mixture gas. In the above structure, the engine can be steadily started, even when the battery 10 runs down. As described above, the battery 10 of a motorcycle with a relatively small displacement (125 cc) is small in capacity. Accordingly, the battery 10 is apt to run down. However, in the above structure, the first condenser 20 supplies electricity to the primary coil 37 and the CPU 26 when the battery 10 runs down. Besides, capacitance of the first condenser 20 is set at 4700 μF, so that the engine can be steadily started. In addition, when the engine is started, in the case where the battery runs down, the diode 30 prohibits electricity from flowing to the battery 10 from the first condenser 20. As a result, electric charge charged in the first condenser 20 can be prevented from being consumed in the battery 10, and all the electric charge charged in the first condenser 20 can be supplied to the primary coil 37 and the CPU 26, so that generation of high voltage in the ignition coil 36 can be stabilized. Besides, the CPU 26 steadily operates when the engine is started and after the engine is started. Thereby, the power transistor 22 is steadily turned ON and OFF. Since when electricity, which is supplied from the alternator 32 and the first condenser 20 to the transformer power source 24, is insufficient, the CPU 26 can be supplied with electricity from the second condenser 28. Here, the second condenser 28 has capacitance that is set at 1000μF, so that reliability of operation of the CPU 26 is high. The igniter 45 includes the first condenser 20, which is constructed of only one condenser, so that the number of components becomes small compared with a structure, which includes the first condenser 20 constructed of multiple condensers. In addition, the first condenser 20 of the igniter 45 has an enhanced heat radiating performance. The condenser accommodating portion 47 is formed in the casing 46 to surround the first condenser 20, and the casing 46 is exposed to outside air. Particularly, the condenser accommodating portion 47 has an inner surface along the outer surface of the first condenser 20, so that heat generated in the first condenser 20 is easily transmitted to the condenser accommodating portion 47. Thereby, the heat transmitted to the condenser accommodating portion 47 can be easily radiated to the outside through the condenser accommodating portion 47. When the motorcycle runs, the outer surface of the condenser accommodating portion 47 decreases in temperature, so that heat radiating performance of the first condenser 20 is further enhanced. The first condenser 20 may be provided to the regulator 33 to backup the battery 10. However, the regulator 33 generates a large amount of heat, and the regulator 33 is relatively high in temperature. By contrast, the first condenser 20 is arranged in the igniter 45 in the above structure, so that thermal load applied to the first condenser 20 decreases. (Second Embodiment) As shown in FIG. 4, the structure of the second embodiment is different from the structure of the first embodiment such that a battery is not provided, and an injector 70, a fuel pump 72, and a third condenser 76 are provided. The injector 70 is a first accessory, and the fuel pump 72 is a second accessory. The third condenser 76 serves as an accessory condenser. Structure excluding the above differences is substantially the same as the structure in the first embodiment. As follows, differences between structures are mainly described. A fourth wiring 60 extends from the alternator 32 to the primary coil 37. A first diode 30 is arranged on the fourth wiring 60. A second wiring (fifth wiring) 64 branches from a branch point 62, and extends to the switching element 22. The transformer power source 24 and the CPU 26 are arranged on the second wiring 64. The first condenser 20 is connected to the branch point 62. An injector 70 is connected to a portion between the branch point 62 and the first condenser 20. The second condenser 28 is connected to a portion between the transformer power source 24 and the CPU 26. The third condenser 76 is connected to the side of the alternator 32 with respect to the first diode 30 via the second diode 78 on the fourth wiring 60. The direction of the second diode 78 is the same as the direction of the first diode 30. The fuel pump 72 is connected to a portion between the third condenser 76 and the second diode 78. The first condenser 20 has capacitance, which is set to be greater than capacitance of the third condenser 76. The structure in the second embodiment may not have a battery. Therefore, engine is started by kicking, so that the engine is rotated. The alternator generates electricity after the engine is started, so that the primary coil 37, the CPU 26, and the like are supplied with the electricity. Besides, the electricity is charged in the first condenser 20, the second condenser 28, and the third condenser 76. Electricity needed for the primary coil 37 may be insufficient by only supplying electricity generated by the alternator 32, depending on rotation speed of the alternator 32, an operating condition of the regulator 33, and performance of the regulator 33, which are subjected to an operating condition, e. g, rotation speed Ne of the engine. When electricity is insufficient, electricity in the first condenser 20 is supplied to the primary coil 37 and the switching element 22. In addition, electricity in the first condenser 20 is supplied to the injector 70, and electricity in the third condenser 76 is supplied to the furl pump 72. In the structure of the second embodiment, the ignition coil 36 generates predetermined high voltage at a predetermined timing using electricity supplied from the first condenser 20, even when electricity supplied from the alternator 32 is unstable. The injector 70 and the fuel pump 72 respectively operate at a predetermined timing using electricity supplied from the first condenser 20 and the third condenser 76. Here, electricity supplied from the first condenser 20 is used for the ignition system and the injector 70. The injector 70 is an accessory (first accessory). However, the first condenser 20 has capacitance that is greater than capacitance of the third condenser 76, so that supplied electricity becomes sufficient. Electricity is prevented from causing reverse flow from the third condenser 76 to the alternator 32 by the second diode 78. Furthermore, the first and the third condensers 20, 76 are provided, and the first and the second diodes 30, 78 are provided, so that electricity passing therethrough becomes small, so that the lifespan of the condensers 20, 76 and the diodes 30, 78 is enhanced. (Variation) As shown in FIG. 5, in a first variation of the second embodiment, the first condenser 20 supplies only the primary coil 37, the CPU 26, and the like with electricity. The third condenser 76 supplies electricity to the injector 70 and the fuel pump 72. That is, the ignition system, which is relatively high in importance, is supplied with electricity form the first condenser 20, which is large in capacitance. On the contrary, accessories, i.e., the injector 70 and the fuel pump 72, which are relatively low in importance, are supplied with electricity form the third condenser 76, which is small in capacitance. As a result, an operation of the ignition system and operations of the injector 70 and the fuel pump 72 become steady. Furthermore, the first and the third condensers 20, 76 are provided, and the first and the second diodes 30, 78 are provided, so that electricity passing therethrough becomes small, so that the lifespan of the condensers 20, 76 and the diodes 30, 78 is enhanced. As shown in FIG. 6, the structure in the second variation has a battery less structure. Besides, the injector, the fuel pump, and the third condenser are not provided to this structure. The battery, the injector, the fuel pump, and the third condenser are not provided, so that the structure of the engine is simplified, and the engine can be downsized. Thereby, cost can be reduced. Here, the battery 10 (FIG. 1) may be provided to this structure. In this case, the structure is equivalent to a variation of the first embodiment. The third condenser 76 may be provided to this structure. In this case, the structure is equivalent to a variation of the second embodiment. An open regulator 80 is provided to a portion between the branch point 14 and the alternator 32. The open regulator 80 includes a zener diode 81, a diode 82, and a thyristor 83. The thyristor 83 is arranged such that the anode of the thyristor 83 is located on the side of the alternator 32. In this variation, the alternator 32 generates electricity, and the electricity passes through the fourth wiring 60. The zener diode 81 restricts an amount of the electricity at a predetermined value. Predetermined voltage is applied to the gate of the thyristor 83 via the diode 82, and the thyristor 83 is turned ON, so that the primary coil 37 and the CPU 26 are supplied with electricity from the alternator 32. The open regulator 80 restricts an amount of the electricity at a predetermined value, even when an amount of electricity becomes higher than a predetermined value due to degradation of the regulator 33 in performance or due to disorder of the regulator 33. Thereby, an amount of electricity supplied from the alternator 32 becomes stable. When an amount of electricity passing through the fourth wiring 60 becomes lower than a predetermined value, the thyristor 83 is turned OFF, so that electricity from the first condenser 20 may not cause reverse flow into the alternator 32. Thus, the open regulator 80 stabilizes electricity from the alternator 32, and supplies the electricity to the primary coil 37, and the like. In addition, the open regulator 80 prevents electric charge accumulated in the first condenser 20 from causing reverse flow to the side of the alternator 32. In the above structure, the ignition apparatus for the engine in the first embodiment includes the ignition coil 36, the battery 10, the power transistor (switching element) 22, the first condenser 20, and the diode (reverse flow preventing means) 30. The ignition coil 36 includes the primary coil 37 and the secondary coil. The battery 10 supplies electricity to the primary coil 37. The switching element 22 controls primary electricity, which passes through the primary coil 37. The first condenser 20 is arranged to be in parallel with the battery 10. The first condenser 20 supplies electricity to the primary coil 37 and the switching element 22 when the battery 10 runs down. The reverse flow preventing means 30 prevents electricity from causing reverse flow from the first condenser 20 to the battery 10. The ignition apparatus for the engine according to the second embodiment includes the ignition coil 36, the alternator 32, the switching element 22, the first condenser 20, and the third condenser (accessory condenser) 76. The ignition coil 36 includes the primary coil 37 and the secondary coil. The alternator 32 is operated by the internal combustion engine for supplying electricity to the primary coil 37. The switching element 22 controls primary electricity, which passes through the primary coil 37. The first condenser 20 supplies electricity to at least the primary coil 37 and the switching element 22 when electricity supply from the alternator 32 is unstable. The third condenser 76 is capable of supplying electricity to the injector (first accessory) 70 and the fuel pump (second accessory) 72 when electricity supply from the alternator 32 is unstable. The structure in the second embodiment may include the battery. In the first and the second embodiments, an internal combustion engine may be a 4-cycle engine or a 2-cycle engine. The engine may be capable of rotating at high speed, e. g, 10000 rpm, and the engine has a relatively small displacement, e. g., equal to or less than 125 cc. The engine may be a single cylinder engine, and may be a multicylinder engine. A 2-cycle engine is typically used in a motorcycle. However, a 2-cycle engine is also used in an automobile, a ship, a snowmobile, and a buggy. The engine preferably includes a battery 10, i.e., a DC power source. However, a battery 10 is not necessarily indispensable. The structure in the first embodiment is conceived to include a battery 10. When the engine is started, direct current is supplied from the battery 10 to an end of the primary coil 37 via a first wiring 12, and the direct current is supplied to the switching element 22, which is connected to the other end of the primary coil 37, via the second wiring 16. The structure in the second embodiment is conceived to be a battery less structure, in which rotating power is externally applied to the engine by kicking or the like to start the engine. The alternator 32 generates electricity after the engine is started, so that the electricity is supplied to the primary coil 37 and the igniter in the first and the second embodiments. The numbers of phases and poles are not limited to the alternator 32. Here, the primary coil 37 and the igniter 45 are supplied with electricity using the first condenser 20 when the batter runs down. Alternatively, the primary coil 37 and the igniter 45 are supplied with electricity using the alternator 32 after the engine is started. Therefore, the capacitance of the first condenser 20 can be reduced, as the number of phases of the alternator 32 is increased. The ignition apparatus is constructed of the ignition coil 36 and the igniter 45. The ignition coil 36 includes the primary coil 37 and the secondary coil 38. The igniter ignites using the induction discharge system. Primary electricity passing though the primary coil 37 is turned off using the switching element 22 (e.g., power transistor), which is operated with electricity supplied from the battery 10 or the alternator 32, so that high voltage is generated in the secondary coil 38. The igniter 45 includes at least the switching element 22 and the first condenser 20. The igniter 45 may further include the second condenser 28 and/or a third condenser 76. The igniter may be arranged inside the side cowling, under a seat, or under a tank, as appropriate. The switching element 22, the first condenser 20, and the like are arranged on the substrate 48. The substrate 48 includes the first wiring 12 and the second wiring. The first wiring 12 extends from the battery 10 to the primary coil 37. The second wiring branches from the branch point in an intermediate portion of the first wiring 12, and extends to the switching element 22. The first condenser 20 supplies electricity to the primary coil 37 and the switching element 22, mainly when the battery 10 runs down, or mainly when the alternator 32 is unstably operated, in the first and the second embodiments. The first condenser 20 is preferably arranged on the branch point. The first condenser 20 may be constructed of one part, when the one part of the first condenser 20 has large capacitance, and the first condenser 20 mainly supplies electricity to the igniter 45 and the ignition coil 36. Thereby, the number of components of the ignition apparatus becomes small, when the first condenser 20 is constructed of one part, i.e., when the first condenser 20 is constructed of one condenser. The first condenser 20 has capacitance that is preferably equal to or greater than 1000μF, and is equal to or less than 7000μF. When the capacitance of the first condenser 20 is less than 1000 ΜF, predetermined voltage may not be applied to the primary coil 37 and the switching element 22. When the capacitance of the first condenser 20 is greater than 7000 μF, the engine may not be properly started. That is, when the battery 10 of the motorcycle runs down, a crankshaft needs to be rotated by kicking or by push-start. Accordingly, rotation speed of the engine needs to be increased to charge the condenser, and generated voltage needs to be increased up to voltage equal to or greater than a threshold of starting voltage. In FIG. 3, the horizontal axis shows rotation speed Ne of the engine, and the vertical axis shows voltage for starting the engine. When capacitance C of the condenser is small, charging curve quickly rises, so that starting voltage at a threshold Vth for starting can be secured at relatively low rotation speed n1 of the engine. That is, starting voltage at the threshold Vth can be secured with relatively small power of stepping a kick pedal. On the contrary, when capacitance C of the condenser is large, charging curve slowly rises. Accordingly, starting voltage at the threshold Vth cannot be secured without generating relatively high rotation speed n2 of the engine. That is, starting voltage at the threshold Vth cannot be secured without relatively large power of stepping the kick pedal. The first condenser 20 has large capacitance, and has a large body. The first condenser 20 generates heat when the first condenser 20 is operated. The first condenser 20 may decrease in performance due to increase in temperature. Therefore, a heat radiating means is preferably provided around the first condenser 20. The heat radiating means may be constructed of a cylindrical condenser accommodating portion 47 that accommodates the first condenser 20, which is in a column shape, for example. Heat generated in the first condenser 20 is radiated to the outside via the condenser accommodating portion 47. The condenser accommodating portion 47 is exposed to outside air, so that heat of the first condenser 20 can be further radiated. The transformer power source 24 and the CPU (controller) 26 can be arranged on the second wiring 16 in the first and the second embodiments. The transformer power source 24 transforms voltage generated in the battery 10, and supplies the controller 26 with electricity at the voltage. The controller 26 controls ON and OFF states of the switching element 22. The second condenser 28 is connected between the transformer power source 24 and the controller 26, and is charged by the transformer power source 24, so that the second condenser 28 supplies electricity to the controller 26 in cooperation with the first condenser 20, mainly when the battery 10 runs down. That is, when the battery 10 runs down, the controller 26 is supplied with electricity from the first condenser 20. However, electricity supplied from the first condenser 20 is also supplied to the primary coil 37. Accordingly, electricity supplied to the transformer power source 24 may be insufficient. Therefore, the second condenser 28 is provided, so that the second condenser 28 steadily operates the controller 26 in cooperation with the first condenser 20. The second condenser 28 has capacitance that is preferably equal to or greater than 500 μF, and is equal to or less than 1000 μF. When the capacitance of the second condenser 28 is less than 500 μF, predetermined voltage may not be applied to the controller 26. When the capacitance of the second condenser 28 is greater than 1000 μF, the charging curve thereof slowly rises, and the engine may not be properly started. The third condenser 76 in the second embodiment supplies electricity mainly to the first accessory 70 and the second accessory 72 excluding the ignition system, e. g, the primary coil 37 and the igniter 45. However, the third condenser 76 may supply electricity to the ignition system. The first accessory 70 is the injector 70, for example. The second accessory 72 is the fuel pump 72, for example. The third condenser 76 may be arranged on the fourth wiring between the alternator 32 and the branch point. The number of the third condenser 76 may be one, or may be equal to or greater than two. The third condenser 76 may supply electricity to the first accessory 70 in cooperation with the first condenser 20. The third condenser 76 may supply electricity to the first and second accessories 70, 72. The reverse flow preventing means 30 in the first embodiment prevents electricity from flowing to the alternator 32 from the first condenser 20. The reverse flow preventing means 30 may be constructed of a diode or a thyristor. A diode or the like is provided between the first condenser 20 and the battery 10 in the first embodiment. The reverse flow preventing means 30 is provided between the first condenser 20 and the alternator 32, and is provided between the third condenser 76 and the alternator 32 in the second embodiment. According to the ignition apparatus for the engine in the first embodiment, when the battery 10 runs down, the first condenser 20 supplies electricity to the primary coil 37 and the switching element 22, so that the ignition coil 36 can generate high voltage. In this situation, the reverse flow preventing means 30 restricts electricity, which is caused by electric charge accumulated in the first condenser 20, from being consumed by the battery 10, so that the primary coil 37 and the switching element 22 can be steadily supplied with electricity. According to the ignition apparatus for the engine as described above, when the battery 10 runs down, the first condenser 20 can supply electricity to the primary coil 37 and the switching element 22. In the above structure, the first condenser 20 may not become needlessly large, and may not become insufficient in capacitance. In the above structure, the number of the first condenser 20 is one, so that the first condenser 20 becomes low in cost, and a mounting space becomes small. In the above structure, electricity is transformed in the transformer power source 24, and the electricity is supplied to the controller 26, so that the controller 26 steadily operates. Besides, when the battery 10 runs down, the second condenser 28 supplies electricity to the controller 26, so that turning the switching element 22 ON and OFF can be steadily performed. In the above structure, the second condenser 28 may not become needlessly large, and may not become insufficient in capacitance. In the above structure, reverse flow of electricity can be steadily prevented using a cheap element. In the ignition apparatus for the engine in the second embodiment, even when the alternator 32 unstably supplies electricity, i.e., the alternator 32 insufficiently supplies electricity, the primary coil 37 and the switching element 22 can be supplied with electricity from the first condenser 20, so that the secondary coil 38 can generate high voltage. In addition, the accessory, i.e., the injector 70 can be stably operated with the first condenser 20. In the above structure, the first condenser 20 is arranged at the branch point 62, so that the first condenser 20 may not become needlessly large, and may not become insufficient in capacitance. In the above structure, electric charge in the first and the third condensers 20, 76 can be prevented from flowing to the side of the alternator 32, and can be supplied to the primary coil 37 or the like. In the above structure, the first condenser 20 having large capacitance can supply electricity to the ignition system and the accessories 70, 72. In the above structure, the first condenser 20 supplies electricity to the ignition system, and the third condenser 76 supplies electricity to the accessory 70, 72 individually from the first condenser 20 and the ignition system, so that the ignition system and the accessory 70, 72 can be steadily operated. The above embodiments may be combined as appropriate. Various modifications and alternations may be diversely made to the above embodiments without departing from the spirit of the present invention. Claims: 1. An ignition apparatus for an internal combustion engine, the ignition apparatus igniting mixture gas in a combustion chamber of the internal combustion engine, the ignition apparatus characterized by comprising: an ignition coil that includes a primary coil and a secondary coil; a battery that supplies electricity to the primary coil; a switching element that controls primary electricity, which passes through the primary coil; a first condenser that is arranged to be in parallel with the battery, the first condenser supplying electricity to the primary coil and the switching element when the battery runs down; and a reverse flow preventing means that prevents electricity from flowing to the battery from the first condenser. 2. The ignition apparatus according to claim 1, characterized by further comprising: a first wiring that extends from the battery to the primary coil; and a second wiring that extends from a branch point, which is located at an intermediate point in the first wiring, to the switching element, wherein the first condenser is arranged at the branch point. 3. The ignition apparatus according to claim 1 or 2, wherein the first condenser is arranged between the reverse flow preventing means and the primary coil. 4. The ignition apparatus according to claim 3, wherein the first condenser is arranged between the reverse flow preventing means and the switching element. 5. The ignition apparatus according to claim 2, wherein the first condenser has capacitance that is equal to or greater than 1000 μF, and the first condenser has capacitance that is equal to or less than 7000 6. The ignition apparatus according to claim 5, characterized by further comprising: a condenser accommodating portion that accommodates the first condenser, which is in one piece, wherein the condenser accommodating portion is exposed to outside air. 7. The ignition apparatus according to claim 2, characterized by further comprising: a controller that is arranged on the second wiring, the controller controlling the switching element; a transformer power source that transforms voltage of the battery, the transformer power source applying the voltage to the controller; and a second condenser that is connected to a portion between the transformer power source and the controller, the second condenser supplying electricity to the controller. 8. The ignition apparatus according to claim 7, wherein the second condenser has capacitance that is equal to or greater than 500ΜF, and the second condenser has capacitance that is equal to or less than 1000 9. The ignition apparatus according to claim 2, wherein the reverse flow preventing means is at least one of a diode and a thyristor that is arranged between the branch point and the battery. 10. An ignition apparatus for an internal combustion engine, the ignition apparatus igniting mixture gas in a combustion chamber of the internal combustion engine, the ignition apparatus characterized by comprising: an ignition coil that includes a primary coil and a secondary coil; an alternator that is operated by the internal combustion engine, the alternator supplying electricity to the primary coil; a switching element that controls primary electricity, which passes through the primary coil; a first condenser that supplies electricity to at least the primary coil and the switching element when electricity supplied from the alternator is unstable; at least one accessory; and an accessory condenser that supplies electricity to the at least one accessory when electricity supplied from the alternator is unstable. 11. The ignition apparatus according to claim 10, characterized by further comprising: a fourth wiring that extends from the alternator to the primary coil; and a fifth wiring that extends from a branch point, which is located at an intermediate point in the fourth wiring, to the switching element, wherein the first condenser is arranged at the branch point. 12. The ignition apparatus according to claim 10 or 11, characterized by further comprising: a first reverse flow preventing means that is arranged between the first condenser and the alternator; and a second reverse flow preventing means that is arranged between the accessory condenser and the alternator. 13. The ignition apparatus according to claim 12, wherein the at least one accessory includes a first accessory and a second accessory, the first condenser supplies electricity to the primary coil, the switching element, and the first accessory, and the accessory condenser supplies electricity to the second accessory. 14. The ignition apparatus according to claim 12, wherein the first condenser supplies electricity to the primary coil and the switching element, and the accessory condenser supplies electricity to the first accessory and the second accessory. 15. The ignition apparatus according to claim 13 or 14, wherein the first accessory is an injector, and the second accessory is a pump. 16. The ignition apparatus according to claim 10 or 11, characterized by further comprising: a battery that supplies electricity to the primary coil.

Full Text

IGNITION APPARATUS FOR INTERNAL COMBUSTION ENGINE
Description
The present invention relates to an ignition apparatus for an internal combustion engine, the ignition apparatus igniting mixture gas in a combustion chamber of an internal combustion engine for a motorcycle, an automobile, and the like.
Mixture gas is introduced into a combustion chamber of an internal combustion engine, and the mixture gas is ignited with an ignition plug. Here, high voltage for the ignition plug is generated by an ignition coil. That is, electricity passing through a primary coil of the ignition coil is intermitted, so that predetermined low-voltage is generated in the primary coil by self-induction. The low-voltage is boosted by mutual induction between the primary coil and a secondary coil, so that boosted high voltage is applied to the ignition plug via the secondary coil.
A voltage boosting system is roughly classified into CDI (Capacitor Discharge Ignition) system and an induction discharge system, i.e., a full-transistor system. The CDI system is a boosting system, in which high-voltage electricity, which is charged in a condenser of the CDI system, is instantaneously discharged into a primary coil, so that predetermined high voltage is generated in a secondary coil. In this system, decrease of ignition

energy is small, even when rotation speed of the engine is high. In addition, mixture gas can be ignited with electric charge, which is accumulated in the condenser, even when a battery is completely discharged, i.e., the battery runs out. Therefore, the CDI system is generally applied to an engine, which rotates at high speed, and a small displacement motorcycle, that is, a 2-cycle engine.
On the contrary, the induction discharge system is a boosting system, in which primary electricity, which passes through the primary coil, is shut using a switching element of an igniter, so that electricity at predetermined high-voltage is generated in a secondary coil. In this system, a time period, in which spark is generated in an ignition coil, is extended, so that the system can steadily ignite even lean mixture gas. Therefore, the induction discharge system is generally applied to an automobile and a large displacement motorcycle, that is, a 4-cycle engine, to which high fuel efficiency is demanded.
In recent years, emission regulations are apt to be intensified with respect to motorcycles. Accordingly, the number of motorcycles with 4-cycle engines, which can easily meet emission regulations, is apt to increase. Particularly, the tendency is remarkable in a small displacement motorcycle, so that an igniter using the induction discharge system is apt to be applied to a small displacement motorcycle in consideration of fuel efficiency. A battery of a motorcycle is small in capacity, accordingly, the battery is apt to run down. When the battery runs down, the primary coil and the igniter cannot be supplied

with electricity. Therefore, when an igniter using the induction discharge system is applied to a small displacement motorcycle, a special structure needs to be provided to steadily start an engine when a battery runs down.
According to a conventional igniter disclosed in JP-A-2001 -349270, a condenser is connected in parallel with a primary coil, so that electric charge is accumulated in a condenser when an engine is rotated. Thereby, the electric charge, which is accumulated in the condenser, is used for starting the engine, in the case where the battery runs down.
A battery-less small displacement motorcycle, which does not have a battery, is used in consideration of reduction of a vehicle body in weight, maintenance free, and a safety measure for prevention of theft of a battery. In this case, an engine is started by kicking, and an alternator supplies a primary coil and an igniter with electricity after the engine is started. However, electricity supplied from the alternator may become unstable depending on rotation speed of the alternator and performance of a regulator, which rectifies alternate current into direct current. Accordingly, in this case, electricity needs to be supplied using a condenser.
The condenser in above conventional ignition apparatus is connected with a wiring (line) that connects a battery with a primary coil. Accordingly, when the battery runs down, electricity passes from the condenser not only to a primary coil but also to the battery. The battery acts as a resister, and electric charge, which is accumulated in the condenser, is consumed in the battery. As

a result, the primary coil and the igniter may not be supplied with predetermined electricity.
In view of the foregoing problems, it is an object of the present invention to produce an ignition apparatus for an internal combustion engine using an induction discharge system, the ignition apparatus being capable of steadily igniting mixture gas, even in starting when a mounted battery runs down, and even when an alternator unstably supplies electricity in a battery less system.
According to the present invention, an ignition apparatus for an internal combustion engine ignites mixture gas in a combustion chamber of the internal combustion engine. The ignition apparatus includes an ignition coil, a battery, a switching element, a first condenser, and a reverse flow preventing means. The ignition coil includes a primary coil and a secondary coil. The battery supplies electricity to the primary coil. The switching element controls primary electricity, which passes through the primary coil. The first condenser is arranged to be in parallel with the battery. The first condenser supplies electricity to the primary coil and the switching element when the battery runs down. The reverse flow preventing means prevents electricity from flowing to the battery from the first condenser.
The ignition apparatus further includes a first wiring and a second wiring. The first wiring extends from the battery to the primary coil. The second wiring extends from a branch point, which is located at an intermediate

point in the first wiring, to the switching element. The first condenser is arranged at the branch point.
The first condenser is arranged between the reverse flow preventing means and the primary coil. The first condenser is arranged between the reverse flow preventing means and the switching element. The first condenser has capacitance that is equal to or greater than 1000 μF, and is equal to or less than 7000 μF.
The ignition apparatus further includes a condenser accommodating portion that accommodates the first condenser, which is in one piece. The condenser accommodating portion is exposed to outside air
The ignition apparatus further includes a controller, a transformer power source, and a second condenser. The controller is arranged on the second wiring. The controller controls the switching element. The transformer power source transforms voltage of the battery. The transformer power source applies the voltage to the controller. The second condenser is connected to a portion between the transformer power source and the controller. The second condenser is capable of supplying electricity to the controller.
The second condenser has capacitance that is equal to or greater than 500 μF, and is equal to or less than 1000μF.
The reverse flow preventing means is at least one of a diode and a thyristor that is arranged between the branch point and the battery.
Alternatively, an ignition apparatus for an internal combustion engine

ignites mixture gas in a combustion chamber of the internal combustion engine. The ignition apparatus includes an ignition coil, an alternator, a switching element, a first condenser, and an accessory condenser. The ignition coil includes a primary coil and a secondary coil. The alternator is operated by the internal combustion engine. The alternator supplies electricity to the primary coil. The switching element controls primary electricity, which passes through the primary coil. The first condenser supplies electricity to at least the primary coil and the switching element when electricity supplied from the alternator is unstable. The accessory condenser supplies electricity to an accessory when electricity supplied from the alternator is unstable.
The ignition apparatus further includes a fourth wiring and a fifth wiring. The fourth wiring extends from the alternator to the primary coil. The fifth wiring extends from a branch point, which is located at an intermediate point in the fourth wiring, to the switching element. The first condenser is arranged at the branch point.
The ignition apparatus further includes a first reverse flow preventing means and a second reverse flow preventing means. The first reverse flow preventing means is arranged between the first condenser and the alternator. The second reverse flow preventing means is arranged between the accessory condenser and the alternator.
The ignition apparatus further includes a first accessory and a second accessory. The first condenser supplies electricity to the primary coil, the

switching element, and the first accessory. The accessory condenser supplies electricity to the second accessory. The first accessory may be an injector. The second accessory may be a pump.
The first condenser supplies electricity to the primary coil and the switching element. The accessory condenser supplies electricity to the first accessory and the second accessory.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
FIG. 1 is a block diagram showing an ignition apparatus for an internal combustion engine according to a first embodiment of the present invention;
FIG. 2 is a perspective view showing an igniter according to the first embodiment;
FIG. 3 is a graph showing a relationship between rotation speed Ne of an engine and voltage Vth for starting the engine when the engine is started by kicking;
FIG. 4 is a block diagram showing an ignition apparatus for an internal combustion engine according to a second embodiment of the present invention;
FIG. 5 is a block diagram according to a first variation of the second embodiment; and
FIG. 6 is a block diagram according to a second variation.

(First Embodiment)
An ignition apparatus is applied to an ignition apparatus for an internal combustion engine of a motorcycle with a displacement of 125 cc, in the following description.
As shown in FIG. 1, a first wiring 12 extends from a battery 10 to a primary coil 37 of an ignition coil 36. A diode 30 is arranged on the first wiring 12. The diode 30 serves as a reverse flow preventing means. A second wiring 16 branches from a branch point 14 on the downstream side of the diode 30, and extends to a gate of a power transistor 22. The power transistor 22 serves as a switching element. A transformer power source 24 and a CPU 26 are arranged on the second wiring 16. The CPU 26 serves as a controller. A first condenser 20 is connected to the branch point 14. A second condenser 28 is connected between the transformer power source 24 and the CPU 26.
A third wiring 18 extends from an alternator 32 to the battery 10. A regulator 33 including a rectifier is arranged on the third wiring 18. A lamp 34 is connected to the regulator 33. The alternator 32 is arranged on the high voltage side with respect to the battery 10. The alternator 32 includes a magnet and a coil. The alternator 32 is operated by the engine, so that the alternator 32 generates alternate current. An ignition coil 36 includes the primary coil 37 and a secondary coil 38. The secondary coil 38 is connected to an ignition plug 39. The primary coil 37 has one end, which is connected to

the battery 10, and has the other end, which is connected to a collector of the power transistor 22.
Next, an igniter 45, which is located on the low-voltage side of the battery 10, is described in reference to FIGS. 1,2. As shown in FIG. 2, the igniter 45 includes a casing 46, a substrate 48, the first condenser 20, and the like. The casing 46 is formed of resin to be in a box shape. The casing 46 is secured to the inside of a side cowling (not shown) to be exposed to outside air. A condenser accommodating portion 47, which is in a partially cylindrical shape, is integrally formed with the casing 46.
The first condenser 20, the second condenser 28, the diode 30, the transformer power source 24, the CPU 26, the power transistor 22, and the like are arranged on the substrate 48. The first condenser 20 in a cylindrical shape is set at 4700 nF in capacitance, so that the first condenser 20 has a relatively large body. The first condenser 20 upwardly protrudes from the substrate 48, and the protruding portion of the first condenser 20 is accommodated in the condenser accommodating portion 47.
The diode 30 is arranged such that the anode of the diode 30 is located on the side of the battery 10, so that the diode 30 permits electricity flowing from the battery 10 to the primary coil 37, the first condenser 20, the transformer power source 24, and the like. The diode 30 prohibits electricity from flowing to the battery 10 from the first condenser 20. The first condenser 20 and the transformer power source 24 are connected in parallel with each

other on the low-voltage side of the diode 30, and are connected in parallel with the primary coil 37 of the ignition coil 36. The second condenser 28 is set at 1000 μF in capacitance. The power transistor 22, which is connected on the low-voltage side of the CPU 26, is turned ON and OFF by the CPU 26, so that electricity supplied from the battery 10 to the primary coil 37 is turned ON and OFF.
Next, an operation of the ignition apparatus is described. A start button (not shown) is operated by a driver, so that the engine is started. In this situation, electricity passes from the battery 10 to the primary coil 37 and the igniter 45. The CPU 26 turns the transistor 22 OFF, and primary electricity is shut, so that high voltage is generated in the secondary coil 38, thereby, the ignition coil 36 ignites mixture gas.
The alternator 32 is rotated by the engine after the engine is started, and alternate current generated in the alternator 32 is rectified through the regulator 33. The rectified current is supplied to the primary coil 37, the transformer power source 24, the CPU 26, and the power transistor 22 through the first wiring 12 and the second wiring 16. Generated current is transformed, i.e., is decreased in voltage through the transformer power source 24, so that the transformed current is used for operating the CPU 26.
The CPU 26 receives a predetermined signal, so that the CPU 26 performs ON/OFF control with respect to the power transistor 22. The power transistor 22 is turned ON, and the battery 10 and the primary coil 37 are

supplied with electricity, so that primary electricity passes through the primary coil 37. The power transistor 22 is turned OFF, and primary electricity is shut, so that the primary coil 37 generates predetermined low-voltage by self-induction. The low-voltage is boosted by mutual induction between the primary coil 37 and the secondary coil 38, so that boosted high voltage is applied to the ignition plug 39 via the secondary coil 38. Alternate current is generated in the alternator 32, and the alternate current is rectified through the regulator 33 to be direct current. The direct current, which is rectified through the regulator 33, is charged in the first condenser 20. Direct current, which is charged in the first condenser 20 as electric charge, is transformed in voltage through the transformer power source 24. The transformed current is charged in the second condenser 28 as electric charge.
When the battery 10 runs down, electric charge accumulated in the first condenser 20 is supplied to the primary coil 37, the transformer power source 24, and the like to start the engine. Besides, electric charge accumulated in the second condenser 28 is supplied to the CPU 26. Thereby, the ignition coil 36 generates high voltage, so that the ignition plug 39 ignites mixture gas.
In the above structure, the engine can be steadily started, even when the battery 10 runs down. As described above, the battery 10 of a motorcycle with a relatively small displacement (125 cc) is small in capacity. Accordingly, the battery 10 is apt to run down. However, in the above structure, the first

condenser 20 supplies electricity to the primary coil 37 and the CPU 26 when the battery 10 runs down. Besides, capacitance of the first condenser 20 is set at 4700 μF, so that the engine can be steadily started.
In addition, when the engine is started, in the case where the battery runs down, the diode 30 prohibits electricity from flowing to the battery 10 from the first condenser 20. As a result, electric charge charged in the first condenser 20 can be prevented from being consumed in the battery 10, and all the electric charge charged in the first condenser 20 can be supplied to the primary coil 37 and the CPU 26, so that generation of high voltage in the ignition coil 36 can be stabilized.
Besides, the CPU 26 steadily operates when the engine is started and after the engine is started. Thereby, the power transistor 22 is steadily turned ON and OFF. Since when electricity, which is supplied from the alternator 32 and the first condenser 20 to the transformer power source 24, is insufficient, the CPU 26 can be supplied with electricity from the second condenser 28. Here, the second condenser 28 has capacitance that is set at 1000μF, so that reliability of operation of the CPU 26 is high. The igniter 45 includes the first condenser 20, which is constructed of only one condenser, so that the number of components becomes small compared with a structure, which includes the first condenser 20 constructed of multiple condensers.
In addition, the first condenser 20 of the igniter 45 has an enhanced heat radiating performance. The condenser accommodating portion 47 is

formed in the casing 46 to surround the first condenser 20, and the casing 46 is exposed to outside air. Particularly, the condenser accommodating portion 47 has an inner surface along the outer surface of the first condenser 20, so that heat generated in the first condenser 20 is easily transmitted to the condenser accommodating portion 47. Thereby, the heat transmitted to the condenser accommodating portion 47 can be easily radiated to the outside through the condenser accommodating portion 47. When the motorcycle runs, the outer surface of the condenser accommodating portion 47 decreases in temperature, so that heat radiating performance of the first condenser 20 is further enhanced.
The first condenser 20 may be provided to the regulator 33 to backup the battery 10. However, the regulator 33 generates a large amount of heat, and the regulator 33 is relatively high in temperature. By contrast, the first condenser 20 is arranged in the igniter 45 in the above structure, so that thermal load applied to the first condenser 20 decreases. (Second Embodiment)
As shown in FIG. 4, the structure of the second embodiment is different from the structure of the first embodiment such that a battery is not provided, and an injector 70, a fuel pump 72, and a third condenser 76 are provided. The injector 70 is a first accessory, and the fuel pump 72 is a second accessory. The third condenser 76 serves as an accessory condenser. Structure excluding the above differences is substantially the same as the structure in the first embodiment. As follows, differences between structures

are mainly described.
A fourth wiring 60 extends from the alternator 32 to the primary coil 37. A first diode 30 is arranged on the fourth wiring 60. A second wiring (fifth wiring) 64 branches from a branch point 62, and extends to the switching element 22. The transformer power source 24 and the CPU 26 are arranged on the second wiring 64. The first condenser 20 is connected to the branch point 62. An injector 70 is connected to a portion between the branch point 62 and the first condenser 20.
The second condenser 28 is connected to a portion between the transformer power source 24 and the CPU 26. The third condenser 76 is connected to the side of the alternator 32 with respect to the first diode 30 via the second diode 78 on the fourth wiring 60. The direction of the second diode 78 is the same as the direction of the first diode 30. The fuel pump 72 is connected to a portion between the third condenser 76 and the second diode 78. The first condenser 20 has capacitance, which is set to be greater than capacitance of the third condenser 76.
The structure in the second embodiment may not have a battery. Therefore, engine is started by kicking, so that the engine is rotated. The alternator generates electricity after the engine is started, so that the primary coil 37, the CPU 26, and the like are supplied with the electricity. Besides, the electricity is charged in the first condenser 20, the second condenser 28, and the third condenser 76.

Electricity needed for the primary coil 37 may be insufficient by only supplying electricity generated by the alternator 32, depending on rotation speed of the alternator 32, an operating condition of the regulator 33, and performance of the regulator 33, which are subjected to an operating condition, e. g, rotation speed Ne of the engine. When electricity is insufficient, electricity in the first condenser 20 is supplied to the primary coil 37 and the switching element 22. In addition, electricity in the first condenser 20 is supplied to the injector 70, and electricity in the third condenser 76 is supplied to the furl pump 72.
In the structure of the second embodiment, the ignition coil 36 generates predetermined high voltage at a predetermined timing using electricity supplied from the first condenser 20, even when electricity supplied from the alternator 32 is unstable. The injector 70 and the fuel pump 72 respectively operate at a predetermined timing using electricity supplied from the first condenser 20 and the third condenser 76. Here, electricity supplied from the first condenser 20 is used for the ignition system and the injector 70. The injector 70 is an accessory (first accessory). However, the first condenser 20 has capacitance that is greater than capacitance of the third condenser 76, so that supplied electricity becomes sufficient.
Electricity is prevented from causing reverse flow from the third condenser 76 to the alternator 32 by the second diode 78. Furthermore, the first and the third condensers 20, 76 are provided, and the first and the second

diodes 30, 78 are provided, so that electricity passing therethrough becomes small, so that the lifespan of the condensers 20, 76 and the diodes 30, 78 is enhanced. (Variation)
As shown in FIG. 5, in a first variation of the second embodiment, the first condenser 20 supplies only the primary coil 37, the CPU 26, and the like with electricity. The third condenser 76 supplies electricity to the injector 70 and the fuel pump 72. That is, the ignition system, which is relatively high in importance, is supplied with electricity form the first condenser 20, which is large in capacitance. On the contrary, accessories, i.e., the injector 70 and the fuel pump 72, which are relatively low in importance, are supplied with electricity form the third condenser 76, which is small in capacitance. As a result, an operation of the ignition system and operations of the injector 70 and the fuel pump 72 become steady. Furthermore, the first and the third condensers 20, 76 are provided, and the first and the second diodes 30, 78 are provided, so that electricity passing therethrough becomes small, so that the lifespan of the condensers 20, 76 and the diodes 30, 78 is enhanced.
As shown in FIG. 6, the structure in the second variation has a battery less structure. Besides, the injector, the fuel pump, and the third condenser are not provided to this structure. The battery, the injector, the fuel pump, and the third condenser are not provided, so that the structure of the engine is simplified, and the engine can be downsized. Thereby, cost can be reduced.

Here, the battery 10 (FIG. 1) may be provided to this structure. In this case, the structure is equivalent to a variation of the first embodiment. The third condenser 76 may be provided to this structure. In this case, the structure is equivalent to a variation of the second embodiment.
An open regulator 80 is provided to a portion between the branch point 14 and the alternator 32. The open regulator 80 includes a zener diode 81, a diode 82, and a thyristor 83. The thyristor 83 is arranged such that the anode of the thyristor 83 is located on the side of the alternator 32. In this variation, the alternator 32 generates electricity, and the electricity passes through the fourth wiring 60. The zener diode 81 restricts an amount of the electricity at a predetermined value. Predetermined voltage is applied to the gate of the thyristor 83 via the diode 82, and the thyristor 83 is turned ON, so that the primary coil 37 and the CPU 26 are supplied with electricity from the alternator 32.
The open regulator 80 restricts an amount of the electricity at a predetermined value, even when an amount of electricity becomes higher than a predetermined value due to degradation of the regulator 33 in performance or due to disorder of the regulator 33. Thereby, an amount of electricity supplied from the alternator 32 becomes stable. When an amount of electricity passing through the fourth wiring 60 becomes lower than a predetermined value, the thyristor 83 is turned OFF, so that electricity from the first condenser 20 may not cause reverse flow into the alternator 32. Thus, the open regulator 80

stabilizes electricity from the alternator 32, and supplies the electricity to the primary coil 37, and the like. In addition, the open regulator 80 prevents electric charge accumulated in the first condenser 20 from causing reverse flow to the side of the alternator 32.
In the above structure, the ignition apparatus for the engine in the first embodiment includes the ignition coil 36, the battery 10, the power transistor (switching element) 22, the first condenser 20, and the diode (reverse flow preventing means) 30. The ignition coil 36 includes the primary coil 37 and the secondary coil. The battery 10 supplies electricity to the primary coil 37. The switching element 22 controls primary electricity, which passes through the primary coil 37. The first condenser 20 is arranged to be in parallel with the battery 10. The first condenser 20 supplies electricity to the primary coil 37 and the switching element 22 when the battery 10 runs down. The reverse flow preventing means 30 prevents electricity from causing reverse flow from the first condenser 20 to the battery 10.
The ignition apparatus for the engine according to the second embodiment includes the ignition coil 36, the alternator 32, the switching element 22, the first condenser 20, and the third condenser (accessory condenser) 76. The ignition coil 36 includes the primary coil 37 and the secondary coil. The alternator 32 is operated by the internal combustion engine for supplying electricity to the primary coil 37. The switching element 22 controls primary electricity, which passes through the primary coil 37. The

first condenser 20 supplies electricity to at least the primary coil 37 and the switching element 22 when electricity supply from the alternator 32 is unstable. The third condenser 76 is capable of supplying electricity to the injector (first accessory) 70 and the fuel pump (second accessory) 72 when electricity supply from the alternator 32 is unstable. The structure in the second embodiment may include the battery.
In the first and the second embodiments, an internal combustion engine may be a 4-cycle engine or a 2-cycle engine. The engine may be capable of rotating at high speed, e. g, 10000 rpm, and the engine has a relatively small displacement, e. g., equal to or less than 125 cc. The engine may be a single cylinder engine, and may be a multicylinder engine. A 2-cycle engine is typically used in a motorcycle. However, a 2-cycle engine is also used in an automobile, a ship, a snowmobile, and a buggy.
The engine preferably includes a battery 10, i.e., a DC power source. However, a battery 10 is not necessarily indispensable. The structure in the first embodiment is conceived to include a battery 10. When the engine is started, direct current is supplied from the battery 10 to an end of the primary coil 37 via a first wiring 12, and the direct current is supplied to the switching element 22, which is connected to the other end of the primary coil 37, via the second wiring 16. The structure in the second embodiment is conceived to be a battery less structure, in which rotating power is externally applied to the engine by kicking or the like to start the engine.

The alternator 32 generates electricity after the engine is started, so that the electricity is supplied to the primary coil 37 and the igniter in the first and the second embodiments. The numbers of phases and poles are not limited to the alternator 32. Here, the primary coil 37 and the igniter 45 are supplied with electricity using the first condenser 20 when the batter runs down. Alternatively, the primary coil 37 and the igniter 45 are supplied with electricity using the alternator 32 after the engine is started. Therefore, the capacitance of the first condenser 20 can be reduced, as the number of phases of the alternator 32 is increased.
The ignition apparatus is constructed of the ignition coil 36 and the igniter 45. The ignition coil 36 includes the primary coil 37 and the secondary coil 38. The igniter ignites using the induction discharge system. Primary electricity passing though the primary coil 37 is turned off using the switching element 22 (e.g., power transistor), which is operated with electricity supplied from the battery 10 or the alternator 32, so that high voltage is generated in the secondary coil 38.
The igniter 45 includes at least the switching element 22 and the first condenser 20. The igniter 45 may further include the second condenser 28 and/or a third condenser 76. The igniter may be arranged inside the side cowling, under a seat, or under a tank, as appropriate. The switching element 22, the first condenser 20, and the like are arranged on the substrate 48. The substrate 48 includes the first wiring 12 and the second wiring. The first wiring

12 extends from the battery 10 to the primary coil 37. The second wiring branches from the branch point in an intermediate portion of the first wiring 12, and extends to the switching element 22.
The first condenser 20 supplies electricity to the primary coil 37 and the switching element 22, mainly when the battery 10 runs down, or mainly when the alternator 32 is unstably operated, in the first and the second embodiments. The first condenser 20 is preferably arranged on the branch point. The first condenser 20 may be constructed of one part, when the one part of the first condenser 20 has large capacitance, and the first condenser 20 mainly supplies electricity to the igniter 45 and the ignition coil 36. Thereby, the number of components of the ignition apparatus becomes small, when the first condenser 20 is constructed of one part, i.e., when the first condenser 20 is constructed of one condenser.
The first condenser 20 has capacitance that is preferably equal to or greater than 1000μF, and is equal to or less than 7000μF. When the capacitance of the first condenser 20 is less than 1000 ΜF, predetermined voltage may not be applied to the primary coil 37 and the switching element 22. When the capacitance of the first condenser 20 is greater than 7000 μF, the engine may not be properly started. That is, when the battery 10 of the motorcycle runs down, a crankshaft needs to be rotated by kicking or by push-start. Accordingly, rotation speed of the engine needs to be increased to charge the condenser, and generated voltage needs to be increased up to

voltage equal to or greater than a threshold of starting voltage.
In FIG. 3, the horizontal axis shows rotation speed Ne of the engine, and the vertical axis shows voltage for starting the engine. When capacitance C of the condenser is small, charging curve quickly rises, so that starting voltage at a threshold Vth for starting can be secured at relatively low rotation speed n1 of the engine. That is, starting voltage at the threshold Vth can be secured with relatively small power of stepping a kick pedal. On the contrary, when capacitance C of the condenser is large, charging curve slowly rises. Accordingly, starting voltage at the threshold Vth cannot be secured without generating relatively high rotation speed n2 of the engine. That is, starting voltage at the threshold Vth cannot be secured without relatively large power of stepping the kick pedal.
The first condenser 20 has large capacitance, and has a large body. The first condenser 20 generates heat when the first condenser 20 is operated. The first condenser 20 may decrease in performance due to increase in temperature. Therefore, a heat radiating means is preferably provided around the first condenser 20. The heat radiating means may be constructed of a cylindrical condenser accommodating portion 47 that accommodates the first condenser 20, which is in a column shape, for example. Heat generated in the first condenser 20 is radiated to the outside via the condenser accommodating portion 47. The condenser accommodating portion 47 is exposed to outside air, so that heat of the first condenser 20 can be further radiated.

The transformer power source 24 and the CPU (controller) 26 can be arranged on the second wiring 16 in the first and the second embodiments. The transformer power source 24 transforms voltage generated in the battery 10, and supplies the controller 26 with electricity at the voltage. The controller 26 controls ON and OFF states of the switching element 22. The second condenser 28 is connected between the transformer power source 24 and the controller 26, and is charged by the transformer power source 24, so that the second condenser 28 supplies electricity to the controller 26 in cooperation with the first condenser 20, mainly when the battery 10 runs down.
That is, when the battery 10 runs down, the controller 26 is supplied with electricity from the first condenser 20. However, electricity supplied from the first condenser 20 is also supplied to the primary coil 37. Accordingly, electricity supplied to the transformer power source 24 may be insufficient. Therefore, the second condenser 28 is provided, so that the second condenser 28 steadily operates the controller 26 in cooperation with the first condenser 20. The second condenser 28 has capacitance that is preferably equal to or greater than 500 μF, and is equal to or less than 1000 μF. When the capacitance of the second condenser 28 is less than 500 μF, predetermined voltage may not be applied to the controller 26. When the capacitance of the second condenser 28 is greater than 1000 μF, the charging curve thereof slowly rises, and the engine may not be properly started.
The third condenser 76 in the second embodiment supplies electricity

mainly to the first accessory 70 and the second accessory 72 excluding the ignition system, e. g, the primary coil 37 and the igniter 45. However, the third condenser 76 may supply electricity to the ignition system. The first accessory 70 is the injector 70, for example. The second accessory 72 is the fuel pump 72, for example. The third condenser 76 may be arranged on the fourth wiring between the alternator 32 and the branch point. The number of the third condenser 76 may be one, or may be equal to or greater than two. The third condenser 76 may supply electricity to the first accessory 70 in cooperation with the first condenser 20. The third condenser 76 may supply electricity to the first and second accessories 70, 72.
The reverse flow preventing means 30 in the first embodiment prevents electricity from flowing to the alternator 32 from the first condenser 20. The reverse flow preventing means 30 may be constructed of a diode or a thyristor. A diode or the like is provided between the first condenser 20 and the battery 10 in the first embodiment. The reverse flow preventing means 30 is provided between the first condenser 20 and the alternator 32, and is provided between the third condenser 76 and the alternator 32 in the second embodiment.
According to the ignition apparatus for the engine in the first embodiment, when the battery 10 runs down, the first condenser 20 supplies electricity to the primary coil 37 and the switching element 22, so that the ignition coil 36 can generate high voltage. In this situation, the reverse flow

preventing means 30 restricts electricity, which is caused by electric charge accumulated in the first condenser 20, from being consumed by the battery 10, so that the primary coil 37 and the switching element 22 can be steadily supplied with electricity.
According to the ignition apparatus for the engine as described above, when the battery 10 runs down, the first condenser 20 can supply electricity to the primary coil 37 and the switching element 22. In the above structure, the first condenser 20 may not become needlessly large, and may not become insufficient in capacitance. In the above structure, the number of the first condenser 20 is one, so that the first condenser 20 becomes low in cost, and a mounting space becomes small.
In the above structure, electricity is transformed in the transformer power source 24, and the electricity is supplied to the controller 26, so that the controller 26 steadily operates. Besides, when the battery 10 runs down, the second condenser 28 supplies electricity to the controller 26, so that turning the switching element 22 ON and OFF can be steadily performed. In the above structure, the second condenser 28 may not become needlessly large, and may not become insufficient in capacitance. In the above structure, reverse flow of electricity can be steadily prevented using a cheap element.
In the ignition apparatus for the engine in the second embodiment, even when the alternator 32 unstably supplies electricity, i.e., the alternator 32 insufficiently supplies electricity, the primary coil 37 and the switching element

22 can be supplied with electricity from the first condenser 20, so that the secondary coil 38 can generate high voltage. In addition, the accessory, i.e., the injector 70 can be stably operated with the first condenser 20. In the above structure, the first condenser 20 is arranged at the branch point 62, so that the first condenser 20 may not become needlessly large, and may not become insufficient in capacitance.
In the above structure, electric charge in the first and the third condensers 20, 76 can be prevented from flowing to the side of the alternator 32, and can be supplied to the primary coil 37 or the like. In the above structure, the first condenser 20 having large capacitance can supply electricity to the ignition system and the accessories 70, 72. In the above structure, the first condenser 20 supplies electricity to the ignition system, and the third condenser 76 supplies electricity to the accessory 70, 72 individually from the first condenser 20 and the ignition system, so that the ignition system and the accessory 70, 72 can be steadily operated.
The above embodiments may be combined as appropriate.
Various modifications and alternations may be diversely made to the above embodiments without departing from the spirit of the present invention.

Claims:
1. An ignition apparatus for an internal combustion engine, the ignition apparatus igniting mixture gas in a combustion chamber of the internal combustion engine, the ignition apparatus characterized by comprising:
an ignition coil that includes a primary coil and a secondary coil;
a battery that supplies electricity to the primary coil;
a switching element that controls primary electricity, which passes through the primary coil;
a first condenser that is arranged to be in parallel with the battery, the first condenser supplying electricity to the primary coil and the switching element when the battery runs down; and
a reverse flow preventing means that prevents electricity from flowing to the battery from the first condenser.
2. The ignition apparatus according to claim 1, characterized by further comprising:
a first wiring that extends from the battery to the primary coil; and
a second wiring that extends from a branch point, which is located at an intermediate point in the first wiring, to the switching element,
wherein the first condenser is arranged at the branch point.
3. The ignition apparatus according to claim 1 or 2, wherein the first

condenser is arranged between the reverse flow preventing means and the primary coil.
4. The ignition apparatus according to claim 3, wherein the first condenser is arranged between the reverse flow preventing means and the switching element.
5. The ignition apparatus according to claim 2, wherein the first condenser has capacitance that is equal to or greater than 1000 μF, and
the first condenser has capacitance that is equal to or less than 7000
6. The ignition apparatus according to claim 5, characterized by further comprising:
a condenser accommodating portion that accommodates the first condenser, which is in one piece,
wherein the condenser accommodating portion is exposed to outside air.
7. The ignition apparatus according to claim 2, characterized by further comprising:

a controller that is arranged on the second wiring, the controller controlling the switching element;
a transformer power source that transforms voltage of the battery, the transformer power source applying the voltage to the controller; and
a second condenser that is connected to a portion between the transformer power source and the controller, the second condenser supplying electricity to the controller.
8. The ignition apparatus according to claim 7,
wherein the second condenser has capacitance that is equal to or greater than 500ΜF, and
the second condenser has capacitance that is equal to or less than 1000
9. The ignition apparatus according to claim 2, wherein the reverse flow preventing means is at least one of a diode and a thyristor that is arranged between the branch point and the battery.
10. An ignition apparatus for an internal combustion engine, the ignition apparatus igniting mixture gas in a combustion chamber of the internal combustion engine, the ignition apparatus characterized by comprising:
an ignition coil that includes a primary coil and a secondary coil;

an alternator that is operated by the internal combustion engine, the alternator supplying electricity to the primary coil;
a switching element that controls primary electricity, which passes through the primary coil;
a first condenser that supplies electricity to at least the primary coil and the switching element when electricity supplied from the alternator is unstable;
at least one accessory; and
an accessory condenser that supplies electricity to the at least one accessory when electricity supplied from the alternator is unstable.
11. The ignition apparatus according to claim 10, characterized by further comprising:
a fourth wiring that extends from the alternator to the primary coil; and
a fifth wiring that extends from a branch point, which is located at an intermediate point in the fourth wiring, to the switching element,
wherein the first condenser is arranged at the branch point.
12. The ignition apparatus according to claim 10 or 11, characterized by further comprising:
a first reverse flow preventing means that is arranged between the first condenser and the alternator; and

a second reverse flow preventing means that is arranged between the accessory condenser and the alternator.
13. The ignition apparatus according to claim 12,
wherein the at least one accessory includes a first accessory and a second accessory,
the first condenser supplies electricity to the primary coil, the switching element, and the first accessory, and
the accessory condenser supplies electricity to the second accessory.
14. The ignition apparatus according to claim 12,
wherein the first condenser supplies electricity to the primary coil and
the switching element, and
the accessory condenser supplies electricity to the first accessory and
the second accessory.
15. The ignition apparatus according to claim 13 or 14, wherein the first accessory is an injector, and the second accessory is a pump.
16. The ignition apparatus according to claim 10 or 11, characterized by further comprising:

a battery that supplies electricity to the primary coil.

Documents:

380-CHE-2005 AMANDED CLAIMS 26-10-2009.pdf

380-CHE-2005 EXAMINATION REPORT REPLY RECIEVED 26-10-2009.pdf

380-che-2005-abstract.pdf

380-che-2005-claims.pdf

380-che-2005-correspondnece-others.pdf

380-che-2005-description(complete).pdf

380-che-2005-drawings.pdf

380-che-2005-form 1.pdf

380-che-2005-form 3.pdf

380-che-2005-form 5.pdf

380-che-2005-priority document.pdf

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Patent Number

240996

Indian Patent Application Number

380/CHE/2005

PG Journal Number

25/2010

Publication Date

18-Jun-2010

Grant Date

14-Jun-2010

Date of Filing

05-Apr-2005

Name of Patentee

DENSO CORPORATION

Applicant Address

1-1, SHOWA-CHO, KARIYA-CITY, AICHI-PREF 448-8661, JAPAN

Inventors:

#	Inventor's Name	Inventor's Address
1	SAKAI, KATSUHIRO	C/O DENSON CORPORATION 1-1, SHOWA-CHO, KARIYA-CITY, AICHI-PREF 448-8661, JAPAN

PCT International Classification Number

F02P3/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2005-33115	2005-02-09	Japan
2	2004-114251	2004-04-08	Japan