Title of Invention	IGNITION METHOD AND SYSTEM FOR ENGINE
Abstract	IGNITION METHOD AND SYSTEM FOR ENGINE

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] PROVISIONAL/ COMPLETE SPECIFICATION [See Section 10] "IGNITION METHOD AND SYSTEM FOR ENGINE" HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan, 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo, Japan The following specification particularly describes the nature of the invention and the manner in which it is to be performed :- 55 7=|£L| 2001 ^WTED [Prior Art] At starting an engine, it is necessary to supply a sufficient electric power to an ignition device and thereby supply a large ignition energy to a spark plug. Accordingly, in the case of starting the engine with a load such as a headlight consuming a large power being energized in the condition where the discharge power of a battery is low, there is a possibility that a sufficient electric power may not be supplied to the ignition device to reduce the startability of the engine. [0003] To solve this problem, Japanese Patent Laid-open No. Hei 4-132877 or Japanese Utility Model Registration No. 2518904 has proposed a start control device for temporarily cutting off a lamp load such as a headlight from a power supply line at starting an engine. [0004] [Problem to be Solved by the Invention] An AC voltage generated by a generator is converted into a DC voltage by a filtering" circuit, and this DC voltage is supplied to a battery and an electric load. It is known that this DC voltage is not completely flat, but includes ripple synchronous with the period of the AC voltage generated by the generator. Accordingly, when an 2 ignition timing is provided at the valley of the ripple voltage, a voltage to be supplied from an ignition device (igniter) to an ignition coil is reduced and an ignition energy to be supplied from the ignition coil to a spark plug is therefore reduced. As a result, there is a possibility that sufficient explosion cannot be obtained. " [0005] The ignition coil for the engine includes a primary winding to which a_DC voltage is applied and a secondary winding for generating a voltage according to a current change in the primary winding. The ignition device is generally classified into a full-transistor type such that a current change is generated in the primary winding by cutting off an ignition transistor to interrupt the supply of a current to the primary winding and a CDI type such that electrical charge stored in a capacitor is discharged to the primary winding in synchronism with an ignition timing. [0006] The above-mentioned problem is remarkable especially in a system such that a current change in the primary winding of the ignition coil largely depends on an input voltage to the ignition device at the ignition timing as in the case of adopting a full- transistor type 3 ignition device. [0007] It is accordingly an object of the present invention to provide an ignition method and system for an engine which can supply an always large ignition energy to a spark plug. [0008] [Means for Solving the Problem] In accordance with the present invention, there is provided an ignition system for an engine comprising cranking means for cranking a crankshaft, an AC generator connected to the crankshaft, a filtering circuit for filtering an output from the AC generator, and an ignition device for generating an ignition energy by using an output from the filtering circuit at an ignition timing; wherein the timing when the output from the filtering circuit shows ripple is synchronized with the ignition timing. [0009] With this configuration, a peak of the voltage to be supplied to the ignition device coincides with the ignition timing, so that a high voltage can be supplied from the ignition device to the ignition coil. As a result, a large ignition energy can be supplied to a 4 spark plug connected to the secondary winding of the ignition coil, thereby improving.the startability of the engine. [Mode for Carrying out the Invention] A preferred embodiment of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an. essential part of an engine ignition system to which the present invention is applied. According to the present invention there is provided an ignition system for an engine comprising cranking means for cranking a crankshaft, an AC generator connected to said crankshaft, a filtering circuit for filtering an output from said AC generator, and an ignition device for generating an ignition energy by using an output from said filtering circuit at an ignition timing; wherein the relative positional relation between a rotor and a stator in said AC generator and the relative positional relation between said rotor and said crankshaft are adjusted so that the timing when the output from said filtering circuit shows ripple is synchronized with said ignition timing. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS [FIG. 1] FIG. 1 is a block diagram showing a preferred embodiment of the present invention. [FIG. 2] FIG. 2 is a timing chart showing signal -Waveforms in an essential part of the preferred embodiment shown in FIG. 1. [0011] An AC generator 24 is connected to a crankshaft 18 of an engine. The crankshaft 18 is connected to cranking means such as a kick pedal or a starter motor (both not shown). A regulator 27 performs half-wave rectification of an AC voltage generated by a charge coil 25 of the AC generator 24 to output a DC voltage. The DC voltage output,.from the regulator 27 is supplied both to a battery 29 and through a main switch 28 to a DC load and a full-transistor type (dielectric charge type) ignition device 22. [0012] A pulser coil 23 outputs one pulser signal to the full- transistor type ignition device 22 per rotation of 6 the engine. The full-transistor type ignition device 22 includes an ignition transistor 20 to control the supply and interruption of a current to a primary winding 19a of an ignition coil 19 according to a detection timing of the pulser signal. A spark plug 30 is connected to a secondary winding 19b of the ignition coil 19. The secondary winding 19b generates a high voltage according to a current change in the primary winding 19a and supplies the high voltage to the spark plug 30. [0013] FIG. 2 is a timing chart showing signal waveforms in the essential part of the preferred embodiment. More specifically, a cutoff timing of the ignition transistor 20, an output voltage from the AC generator 24, and an output voltage from the regulator 27 are shown in relation to a rotational position of the crankshaft 18. [0014] In this preferred embodiment, the AC generator 24 has a single-phase eight-pole structure, and the output voltage therefrom is therefore an AC voltage having a period equal to a crank angle of 90 degrees. This AC voltage is subjected to half-wave rectification by the regulator 27 and thereby converted into a substantially DC voltage, which is then supplied to the primary winding 19a of the ignition coil 19. [0015] The output voltage from the regulator 27 includes ripple synchronous with the period of the AC voltage from the AC generator 24. As well known in the art, the full-transistor type ignition device 22 operates so that the ignition transistor 20 cuts off the current supply to the primary winding 19a to generate a current change in the primary winding 19a, thereby generating a high voltage in the secondary winding 19b according to this current change. Accordingly, the larger the applied voltage to the primary winding 19a at the timing of cutting off the ignition transistor 20, the larger ignition energy can be generated in the secondary winding 19b. [0016] In this preferred embodiment, the relative positional relation between a rotor and a stator (both not shown) in the AC generator 24 and the relative positional relation between the rotor and the crankshaft 18 are adjusted so that the ignition transistor 20 of the ignition device 22 is cut off at the timing Tl when the ripple component included in the DC voltage shows a maximum value, in other words, at the timing when the AC voltage shows a maximum value. [0017] According to this preferred embodiment, the timing of cutting off the ignition transistor 20 always coincides with a peak of the generated voltage. Accordingly, a high voltage can be supplied to the primary winding 19a of the ignition coil 19, so that a large ignition energy can be supplied to the spark plug 30. [0018] While the ignition device 22 is of a full-transistor type in the above preferred embodiment, the present invention is not limited to this type, but a CDI type or a combined full - transistor and CDI type may be adopted. Also in any type of ignition device, a similar effect can be obtained. [0019] [Effect of the Invention] According to the present invention, the timing of cutting off the ignition transistor of the ignition device to generate a current change in the primary winding of the ignition coil coincides with a peak of the generated voltage, so that a large current change can be generated in the primary winding. Accordingly, a large ignition energy can be supplied from the secondary 9 winding of the ignition coil to the spark plug, thereby improving the startability of the engine. [Description of Reference Numerals] 18 ... crankshaft; 19 ... ignition coil; 22 ... full- transistor type ignition device; 23 ... pulser coil; 24 . AC generator; 25 ... charge coil; 27 ... regulator; 28 ... main switch; 29 ... battery; 30 ... spark plug 10 We Claim: 1. An ignition system for an engine comprising cranking means for cranking a crankshaft, an AC generator connected to said crankshaft, a filtering circuit for filtering an output from said AC generator, and an ignition device for generating an ignition energy by using an output from said filtering circuit at an ignition timing; wherein the relative positional relation between a rotor and a stator in said AC generator and the relative positional relation between said rotor and said crankshaft are adjusted so that the timing when the output from said filtering circuit shows ripple is synchronized with said ignition timing. 2. An ignition system as claimed in claim 1, wherein said ignition device comprises a primary winding, a secondary winding inductively coupled to said primary winding, and an ignition transistor for controlling the supply and interruption of a current to said primary winding; wherein a current change is generated by cutting off said ignition transistor to interrupt the current to said primary winding, thereby generating a high-voltage ignition energy in said secondary winding. 11

Documents:

557-mum-2001-cancelled pages(2-12-2005).pdf

557-mum-2001-claims(granted)-(2-12-2005).doc

557-mum-2001-claims(granted)-(2-12-2005).pdf

557-mum-2001-correspondence(3-4-2006).pdf

557-mum-2001-correspondence(ipo)-(10-11-2006).pdf

557-mum-2001-drawing(11-7-2001).pdf

557-mum-2001-form 1(18-6-2001).pdf

557-mum-2001-form 18(10-6-2005).pdf

557-mum-2001-form 1a(2-12-2005).pdf

557-mum-2001-form 2(granted)-(2-12-2005).doc

557-mum-2001-form 2(granted)-(2-12-2005).pdf

557-mum-2001-form 3(18-6-2001).pdf

557-mum-2001-form 3(2-1-2006).pdf

557-mum-2001-form 4(3-4-2006).pdf

557-mum-2001-form 5(18-6-2001).pdf

557-mum-2001-petition under rule 137(2-1-2006).pdf

557-mum-2001-petition under rule 138(2-1-2006).pdf

557-mum-2001-power of authority(15-10-2001).pdf

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