JP2007120374A - Capacitor discharge type internal combustion engine ignition device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitor discharge type internal combustion engine ignition device capable of improving ignition performance by prolonging electric discharge time at a time of ignition without causing enlargement of a device and cost increase. <P>SOLUTION: A first primary coil 1a1 and a second primary coil 1a2 are provided in an ignition coil and a first ignition capacitor 401 and a second ignition capacitor 501 are provided in a primary side of the ignition coil. A first and a second ignition circuits 4, 5 are constructed to discharge the first ignition capacitor 401 through a first discharge switch 502 and the first primary coil 1a1 and to discharge the second ignition capacitor 501 through the second discharge switch 502, the first primary coil 1a1 and the second primary coil 1a2 as a series circuit. Then an ignition timing control part 15 is constructed to give trigger signal to the second discharge switch before spark discharge generated in a spark plug disappears after trigger signal is given to the first discharge switch. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a capacitor discharge type ignition device for an internal combustion engine.

  In order to ignite an internal combustion engine mounted on a two-wheeled vehicle, a general-purpose internal combustion engine, or the like, a capacitor discharge type ignition device is used. The capacitor discharge type ignition device includes an ignition coil, an ignition capacitor provided on a primary side of the ignition coil and charged to one polarity by an output of an ignition power supply unit, and stored in the ignition capacitor A discharge switch for discharging the charge through the primary coil of the ignition coil, and by causing a fast rising current to flow through the primary coil of the ignition coil due to the discharge of the charge accumulated in the ignition capacitor, the secondary of the ignition coil A high voltage for ignition is induced in the coil.

  Recently, along with the tightening of exhaust gas regulations of internal combustion engines, in order to further purify exhaust gas, the fuel (air mixture) is diluted and burned. Generally, in order to ignite a lean air-fuel mixture, a spark discharge having a large discharge energy and a long discharge duration is required.

  The capacitor discharge type internal combustion engine ignition device has a short secondary voltage rise time (rise time), so the secondary voltage caused by leakage current due to ignition plug contamination (carbon adhesion to the electrode, etc.) However, it has the advantage that the ignition coil can be made compact. On the other hand, the duration of the discharge that occurs in the discharge gap of the spark plug (secondary current flows through the ignition coil). Has the disadvantage of being short.

  Therefore, an apparatus disclosed in Patent Document 1 has been proposed as a capacitor discharge igniter devised for extending the discharge duration. The ignition device disclosed in Patent Document 1 includes an ignition coil having a single primary coil and a single secondary coil, a capacitor charging power source for generating a capacitor charging voltage, and a primary side of the ignition coil. First and second triggers provided for the first and second ignition capacitors, which are provided and charged to one polarity by the output of the power supply unit, and the first and second ignition capacitors, respectively. First and second discharge switches that conduct when a signal is applied and discharge the electric charge accumulated in the first and second ignition capacitors through the primary side of the ignition coil, and the ignition timing of the internal combustion engine The first trigger signal is applied to the first discharge switch, and the second trigger signal is applied to the second discharge switch before the spark discharge generated in the spark plug due to the conduction of the first discharge switch disappears. Given An ignition timing control unit, and after the first discharge switch is turned on, the first ignition operation is performed, and then the second discharge switch is turned on to perform the second ignition operation. As a result, the discharge duration is lengthened.

  FIG. 5 schematically shows the structure of the ignition device disclosed in Patent Document 1. In FIG. 5, reference numeral 1 denotes an ignition coil having a primary coil 1a and a secondary coil 1b that are grounded at one end. A spark plug 3 is attached to a cylinder of an internal combustion engine (not shown) to which a voltage induced in a secondary coil of the ignition coil is applied, and 3 is a flywheel diode connected to both ends of the primary coil 1a of the ignition coil. Reference numerals 4 and 5 denote first and second ignition circuits, respectively. The first and second ignition circuits 4 and 5 are each connected in common to a terminal on the non-ground side of the primary coil 1a of the ignition coil 1. The first and second ignition capacitors 401 and 501 are connected between the other ends of the ignition capacitors 401 and 501 and the ground, and the first trigger signal Vt1 and the second trigger signal Vt2 are given, respectively. It is composed of first and second discharge switches 402 and 502 that are sometimes conducted and discharge the electric charges accumulated in the ignition capacitors 401 and 501 through the primary coil 1a of the ignition coil 1, respectively. In the illustrated example, the first and second discharge switches 402 and 502 are formed of thyristors Th1 and Th2, respectively.

  Reference numeral 6 denotes an exciter coil provided in the stator of a magnet generator driven by the internal combustion engine. The exciter coil 6 has a negative half-wave voltage Ven and a positive half-wave as shown in FIG. One cycle of the alternating voltage Ve consisting of the voltage Vep is generated once during one revolution of the crankshaft of the engine.

  One end of the exciter coil 6 is connected to the other ends of the first and second ignition capacitors 401 and 501 through a diode 7 whose anode is directed to one end side of the exciter coil. One end of the exciter coil 6 is also connected to a ground circuit through a diode 8 with the cathode facing one end of the exciter coil, and the other end of the exciter coil 6 is grounded through a diode 9 with the cathode facing the other end of the exciter coil. ing.

  The other end of the exciter coil 6 is also connected to the non-grounded input terminal of the power supply circuit 11 through the diode 10 with the anode directed to the other end of the exciter coil 6 and the anode directed to the other end of the exciter coil. The diode 12 is connected to the input terminal of the waveform shaping circuit 13.

  Reference numeral 15 denotes an ignition timing control unit having a microcomputer (CPU), and a negative half-wave voltage Ven output from the exciter coil 6 is inputted to the microcomputer through the waveform shaping circuit 13. As shown in FIG. 6B, the waveform shaping circuit 13 outputs a pulse signal Vp at the rising edge of the negative half-wave voltage Ven. In this example, the pulse signal Vp at the reference crank angle position set at a crank angle position sufficiently advanced from the crank angle position (referred to as the top dead center position) when the piston of the internal combustion engine reaches the top dead center. The positional relationship between the stator and the rotor of the magnet generator is set so that.

  The power supply circuit 11 converts the negative half-wave voltage Ven of the exciter coil 6 into a DC voltage Vcc having a certain level. This DC voltage Vcc is applied to the power supply terminal of the ignition timing control unit 15 and the power supply terminal (not shown) of the waveform shaping circuit 13.

  In the ignition device shown in FIG. 5, when the exciter coil 6 outputs a positive half-wave voltage Vep, the diode 7, the ignition capacitors 401 and 501, the primary coil 1a of the ignition coil and the flywheel diode 3 , A current flows through the diode 9, and the ignition capacitors 401 and 501 are charged to the polarity shown in the figure, and as shown in FIGS. 6C and 6D, the both ends of the capacitors 401 and 501 are respectively connected. The voltages Vc1 and Vc2 rise to the peak value (about 200V) of the positive half-wave voltage Vep.

  The ignition timing control unit 15 determines the rotational speed of the engine from the generation period of the pulse signal Vp obtained by shaping the negative half-wave voltage Ven output from the exciter coil 6 (the time required for the engine to make one revolution). Then, the ignition timing detection timing data T1 used to measure the ignition timing of the engine with respect to the rotational speed is calculated. This ignition timing detection timing data T1 is the time required for the engine crankshaft to rotate from the reference crank angle position (position where the pulse signal Vp is generated) to the crank angle position corresponding to the ignition timing at the current rotational speed. is there.

  The ignition timing control unit 15 also sets the ignition timing detection timing data T1 calculated when the pulse signal Vp is generated (at the reference crank angle position) at the time t1 in the timer, and starts the measurement. When the timer completes the measurement of the ignition timing detection timing data T1 (when the ignition timing is detected), the first trigger signal Vt1 is given to the first discharge switch 402, and then the timer is further set. When the measured delay time T2 is measured, the second trigger signal Vt2 is given to the second discharge switch 502.

  When the first trigger signal Vt1 is applied to the first discharge switch 402, the first discharge switch 402 is turned on, so that the charge accumulated in the first ignition capacitor 401 is changed to the first discharge switch 402. Discharge occurs through 402 and the primary coil 1a of the ignition coil, and a primary current ic1 that rises quickly flows as shown in FIG. In the process of decreasing the primary current ic1 past the peak, an induced voltage in the direction of the arrow shown in the figure (a direction that prevents the decrease of the current ic1) is generated in the primary coil 1a, and the flywheel diode 3 and the primary coil are generated by this induced voltage. A flywheel current if1 flows through 1a.

  Due to the change of the magnetic flux generated in the iron core of the ignition coil due to the flow of the primary current ic1, a high ignition voltage is induced in the secondary coil 1b that is higher than the breakdown voltage (several tens of KV) of the discharge gap of the spark plug 2. Since this ignition high voltage is applied to the spark plug 2, spark discharge occurs between the discharge gaps of the spark plug 2, and a secondary current i 21 flows through the secondary coil 1 b and the spark plug 2 of the ignition coil. The flywheel current if1 acts to increase the time during which the secondary current i21 flows.

The second trigger signal is generated after the first trigger signal Vt1 is generated so that the second discharge switch 502 is turned on while the secondary current i21 flows (while the discharge continues). A delay time T2 until Vt2 is generated is set. When the second trigger signal Vt2 is applied to the second discharge switch 502, the second discharge switch 502 is turned on, so that the charge accumulated in the second ignition capacitor 501 is changed to the second discharge switch 502. Discharge occurs through 502 and the primary coil 1a of the ignition coil, and a primary current ic2 flows as shown in FIG. In the process of decreasing the primary current ic2 past the peak, an induced voltage is generated in the primary coil 1a in the direction indicated by the arrow (in a direction that prevents the decrease in the current ic2), as shown in FIG. 7D. A flywheel current if2 flows through the flywheel diode 3 and the primary coil 1a due to the voltage. As the primary current ic2 that rises quickly flows, the secondary current i22 'rises as shown in FIG. 7E, and the time during which the secondary current flows through the ignition coil (discharge duration) is extended. The voltage between the discharge gaps of the spark plug while the secondary current is flowing through the ignition coil is usually about 2 KV.
JP-A-10-252624

  In the above-described conventional capacitor discharge ignition device, in order to increase the discharge duration, the inductance of the primary coil of the ignition coil may be increased, but the secondary coil has a high ignition voltage (not less than the breakdown voltage of the discharge gap). In order to induce several tens of KV), it is necessary to flow a large current through the primary coil, and there is a limit to increasing the inductance of the primary coil of the ignition coil. For this reason, conventionally, the capacitance of the ignition capacitor has been set large. However, if a capacitor having a large capacitance is used as the ignition capacitor, there is a problem that the ignition device becomes large or costs increase. Arise. Although it is conceivable to provide three ignition circuits, it is not preferable to increase the number of ignition circuits because the structure of the ignition device becomes complicated and the cost increases.

  As an internal combustion engine ignition device, in addition to a capacitor discharge ignition device, there is a primary current interruption type ignition device that induces a high voltage for ignition by interrupting a primary current passed through a primary coil of an ignition coil. Although used, the peak value of the secondary current of the ignition coil flowing in the primary current interrupting ignition device is about 50 mA. On the other hand, the peak value of the secondary current of the ignition coil flowing in the capacitor discharge type ignition device is about 500 mA. In the ignition device shown in FIG. 5, even if the peak value of the secondary current that flows during the operation of the first ignition circuit 4 is required to be about 500 mA, the operation of the second ignition circuit 5 in order to increase the discharge duration time. The peak value of the secondary current that flows sometimes may be equal to the peak value of the secondary current that flows in the primary current interrupting ignition device.

  However, in the conventional ignition device shown in FIG. 5, the peak value of the primary current ic1 that flows when the first ignition circuit 4 operates and the peak value of the primary current ic2 that flows when the second ignition circuit 5 operates. Therefore, the peak value of the secondary current i22 that flows by the operation of the ignition circuit 5 while the secondary current i21 flows by the operation of the ignition circuit 4 is 2 It becomes larger than the peak value of the secondary current i21. Therefore, in the conventional ignition device, there is a problem that the average value of the secondary current that flows during the ignition operation becomes large, and the temperature of the secondary coil of the ignition coil becomes high. Since it was necessary to keep the insulation class high, the cost of the ignition coil could not be avoided.

  SUMMARY OF THE INVENTION An object of the present invention is to improve the ignition performance by extending the discharge duration during the ignition operation without increasing the size of the ignition device and increasing the cost. An object of the present invention is to provide an ignition device.

  The present invention is provided on the primary side of an ignition coil, an ignition coil connected to a secondary side of an ignition plug attached to a cylinder of an internal combustion engine, a capacitor charging power source for generating a capacitor charging voltage, and the like. Provided for each of the first and second ignition capacitors and the first and second ignition capacitors charged to one polarity by the output of the power supply unit, the first and second trigger signals are respectively provided. The first and second discharge switches that conduct when given and discharge the electric charge accumulated in the first and second ignition capacitors through the primary side of the ignition coil, and the first at the ignition timing of the internal combustion engine. The first trigger signal is applied to the first discharge switch, and the second trigger signal is applied to the second discharge switch before the spark discharge generated in the spark plug due to the conduction of the first discharge switch disappears. An ignition device for capacitor discharge type internal combustion engine having an ignition timing control unit of interest.

  In the present invention, the ignition coil includes a first primary coil and a second primary coil connected in series with the first primary coil on the primary side. The first discharge switch is provided so as to discharge the charge accumulated in the first ignition capacitor through the first primary coil when conducting, and the second discharge switch is configured to discharge the charge accumulated in the first primary coil. The charge accumulated in the second ignition capacitor is discharged through a series circuit of a first primary coil and a second primary coil. The first flywheel diode is connected in parallel with the first primary coil of the ignition coil, and in parallel with the series circuit of the first primary coil and the second primary coil of the ignition coil. A second flywheel diode is connected.

  If comprised as mentioned above, in order to enlarge the peak value of the primary current which flows at the time of discharge of the 1st ignition capacitor, the primary coil (1st of the ignition coil which comprises a part of discharge circuit of the 1st ignition capacitor Part of the discharge circuit of the second ignition capacitor by increasing the number of turns of the second primary coil and increasing the inductance of the second primary coil even if the inductance of the primary coil is reduced. The inductance of the primary coil (the series circuit of the first primary coil and the second primary coil) constituting the ignition coil can be sufficiently increased. Therefore, the peak value of the primary current that flows when the first ignition capacitor is discharged flows without limiting the peak value of the primary current that flows when the first ignition capacitor is discharged. It can be made smaller than the peak value of the primary current. Accordingly, while allowing the secondary current having a large peak value to flow when discharging the first ignition capacitor, the peak value of the secondary current flowing when discharging the second ignition capacitor is limited, and the ignition coil The average value of the secondary current of the ignition coil can be reduced, and the temperature rise of the secondary coil of the ignition coil can be suppressed, thereby lowering the insulation class of the ignition coil than before and reducing its cost. You can plan.

  In general, in a capacitor discharge type ignition device, when the capacitance of the ignition capacitor is constant, the spark R generated in the spark plug is smaller as the ratio R / L of the resistance R and inductance L of the primary coil of the ignition coil is smaller. The duration of discharge becomes longer. With the above configuration, the inductance of the primary coil constituting a part of the circuit for discharging the second ignition capacitor is increased without suppressing the peak value of the primary current that flows during the discharge of the first ignition capacitor. Since R / L can be reduced, the discharge duration can be extended without particularly increasing the capacitance of the ignition capacitor or increasing the number of ignition circuits.

  In a preferred aspect of the present invention, the ignition coil is connected in series with the first primary coil, one end of which is grounded at one end and the other end of the first primary coil. And a second primary coil on the primary side, and the other end of the first primary coil and the other end of the second primary coil are respectively connected to one end of the first ignition capacitor and the second ignition capacitor. One end is connected. The first discharge switch and the second discharge switch are connected between the other end of the first ignition capacitor and the ground, and between the other end of the second ignition capacitor and the ground, respectively. A first flywheel diode having a cathode facing the ground side is connected between the other end of the primary coil and the ground, and a cathode is directed to the ground side between the other end of the second primary coil of the ignition coil and the ground. A second flywheel diode is connected.

  As described above, when the first primary coil and the second primary coil are connected in series, it is easy to increase the inductance of the primary coil of the ignition coil that discharges the charge of the second ignition capacitor. become. However, the present invention is not limited to the case where the first primary coil and the second primary coil are connected in series as described above, and the first ignition capacitor and the second ignition capacitor are provided. You may make it discharge through a 1st primary coil and a 2nd primary coil, respectively.

  In this case, a first primary coil and a second primary coil having a larger number of turns than the first primary coil are provided on the primary side of the ignition coil. The first discharge switch is provided so as to discharge the charge accumulated in the first ignition capacitor through the first primary coil when conducting, and the second discharge switch is configured to discharge the charge accumulated in the first primary coil. The charge accumulated in the second ignition capacitor is provided to be discharged through the second primary coil. A first flywheel diode is connected in parallel to the first primary coil of the ignition coil, and a second flywheel diode is connected in parallel to the second primary coil of the ignition coil.

  Even when configured in this way, by increasing the number of turns of the second primary coil and sufficiently increasing the inductance, the first primary coil and the second primary coil are connected in series, The same effect can be obtained as in the case where the second ignition capacitor is discharged through the first primary coil and the second primary coil.

  As described above, according to the present invention, the first primary coil and the second primary coil are provided in the ignition coil, and the first ignition capacitor is discharged through the first primary coil. The first ignition capacitor is discharged through a series circuit of a first primary coil and a second primary coil having a large inductance, or the first ignition capacitor is discharged through the first primary coil, and then the second Since the ignition capacitor is discharged through the second primary coil having an inductance larger than that of the first primary coil, a secondary current having a large peak value is allowed to flow when the first ignition capacitor is discharged. However, the average value of the secondary current of the ignition coil can be reduced by limiting the peak value of the secondary current that flows when the second ignition capacitor is discharged. Therefore, the temperature rise of the secondary coil of the ignition coil can be suppressed, the insulation class of the ignition coil can be made lower than before, and the cost can be reduced.

  Further, according to the present invention, the inductance of the primary coil constituting a part of the circuit for discharging the second ignition capacitor is increased without suppressing the peak value of the primary current that flows during the discharge of the first ignition capacitor. Therefore, the discharge duration can be extended without particularly increasing the capacitance of the ignition capacitor or increasing the number of ignition circuits.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a circuit diagram showing the configuration of the present embodiment. In FIG. 1, parts that are the same as the parts of the conventional ignition device shown in FIG.
In FIG. 1, reference numeral 1 denotes an ignition coil. This ignition coil is connected to the first primary coil 1a1 whose one end is grounded and to the other end of the first primary coil 1a1 and connected to the first primary coil. A second primary coil 1a2 connected in series is provided on the primary side, and one secondary coil 1b having one end grounded is provided on the secondary side. A first flywheel diode 301 having a cathode grounded is connected in parallel to the first primary coil 1a1 of the ignition coil, and a second flywheel diode 302 also having a cathode grounded is connected to the first primary coil 1a1 of the ignition coil. Are connected in parallel to the series circuit of the primary coil and the second primary coil.

  One end of a first ignition capacitor 401 and one end of a second ignition capacitor 501 are connected to the other end of the first primary coil 1a1 and the other end of the second primary coil 1a2, respectively. Thyristors Th1 and Th2 constituting the first discharge switch 402 and the second discharge switch 502 are respectively connected between the other end of the capacitor 401 and the ground and between the other end of the second ignition capacitor 501 and the ground, respectively. The cathode is connected to the ground side.

  A first ignition circuit 4 is configured by the first ignition capacitor 401 and the first discharge switch 402, and the second ignition circuit 5 is configured by the second ignition capacitor 401 and the second discharge switch 402. Is configured.

  Reference numeral 6 denotes an exciter coil provided in a stator of a magnet generator driven by an internal combustion engine. The exciter coil 6 has a negative half-wave voltage Ven and a positive half-wave as shown in FIG. One cycle of the alternating voltage Ve consisting of the voltage Vep is generated only once during one revolution of the crankshaft of the engine.

  As the magnet generator, for example, a magnet magnetized in the radial direction of the flywheel is attached in a recess provided in a part of the outer periphery of the flywheel attached to the crankshaft of the engine, and the outer side of the magnet is installed. A flywheel magnet rotor having three magnetic poles formed by a magnetic pole and flywheel outer peripheral surfaces on both sides of the magnet, an iron core having pole portions opposite to the magnetic pole of the flywheel magnet rotor at both ends, and the iron core What comprises the stator which consists of the wound exciter coil can be used. When such a magnet generator is used, a positive half-wave voltage having a small peak value is generated prior to the negative half-wave voltage Ven having the waveform shown in FIG. A negative half-wave voltage having a small peak value is generated following Vep. In FIG. 2A, a positive and negative half-wave voltage having a small peak value generated before voltage Ven and after voltage Vep is shown. Ignoring.

  One end of the exciter coil 6 is connected to the anode of the diode 7, and the cathode of the diode 7 is connected to the other ends of the first and second ignition capacitors 401 and 501. One end of the exciter coil 6 is also connected to the cathode of the diode 8 whose anode is grounded, and the other end of the exciter coil 6 is connected to the cathode of the diode 9 whose anode is grounded.

  The other end of the exciter coil 6 is also connected to the non-grounded input terminal of the power supply circuit 11 through the diode 10 with the anode directed to the other end of the exciter coil 6 and the anode directed to the other end of the exciter coil. The diode 12 is connected to the input terminal of the waveform shaping circuit 13. As shown in FIG. 2B, the waveform shaping circuit 13 outputs a pulse signal Vp at the rising edge of the negative half-wave voltage Ven. Also in the present embodiment, the pulse signal Vp is generated at the reference crank angle position set to the crank angle position sufficiently advanced from the crank angle position when the piston of the internal combustion engine reaches top dead center. The positional relationship between the stator and rotor of the magnet generator is set. The pulse signal Vp generated by the waveform shaping circuit 13 is input to the microcomputer in the ignition timing control unit 15.

  The power supply circuit 11 converts the negative half-wave voltage Ven of the exciter coil 6 into a DC voltage Vcc having a certain level, and this DC voltage Vcc is supplied to the power supply terminal of the ignition timing control unit 15 and the waveform shaping circuit 13. Give to power terminal.

  In the ignition device shown in FIG. 1, when the exciter coil 6 outputs a positive half-wave voltage Vep, the exciter coil 6-diode 7-ignition capacitor 401-primary coil 1a1 and flywheel diode 301-diode 9 A current flows through the circuit of the exciter coil 6 and the exciter coil 6 -diode 7 -ignition capacitor 501 -the series circuit of the primary coils 1a2 and 1a1 and the flywheel diode 302 -diode 9 -the circuit of the exciter coil 6; The first and second ignition capacitors 401 and 501 are charged with the polarity shown in the figure, and as shown in FIGS. 2C and 2D, the voltages Vc1 and Vc2 across the capacitors 401 and 501 are respectively The positive half-wave voltage Vep increases to the peak value (about 200 V). In this example, the exciter coil 6 and the diodes 7 to 9 constitute a capacitor charging power supply unit that generates a capacitor charging voltage.

  The ignition timing control unit 15 obtains the engine speed from the generation period of the pulse signal Vp obtained by shaping the negative half-wave voltage Ven output from the exciter coil 6, and the engine speed is determined with respect to the engine speed. Timing timing detection timing data T1 used to measure the ignition timing [the crankshaft of the engine rotates at the current rotation speed from the reference crank angle position (position where the pulse signal Vp is generated) to the crank angle position corresponding to the ignition timing. The time required to do] is calculated.

  The ignition timing control unit 15 also sets the ignition timing detection timing data T1 calculated when the pulse signal Vp is generated at the time t1 corresponding to the reference crank angle position in the timer, and starts the measurement. Then, when the timer completes the measurement of the ignition timing detection timing data T1 (when the ignition timing is detected), the first trigger signal Vt1 is given to the first discharge switch 402, and then the timer is set. When the delay time T2 is measured, the second trigger signal Vt2 is given to the second discharge switch 502.

  When the first trigger signal Vt1 is applied to the first discharge switch 402, the first discharge switch 402 is turned on, so that the charge accumulated in the first ignition capacitor 401 is changed to the first discharge switch 402. Discharge occurs through the first primary coil 1a1 having a small inductance 402, and a primary current ic1 having a fast rise flows as shown in FIG. In the process of decreasing the primary current ic1 past the peak, an induced voltage is generated in the primary coil 1a1 in a direction that prevents the current ic1 from decreasing, and this induced voltage causes the flywheel current to pass through the flywheel diode 301 and the primary coil 1a1. If1 (FIG. 3B) flows.

  Due to the change of the magnetic flux generated in the iron core of the ignition coil due to the flow of the primary current ic1, a high ignition voltage is induced in the secondary coil 1b that is higher than the breakdown voltage (several tens of KV) of the discharge gap of the spark plug 2. Since this high voltage for ignition is applied to the spark plug 2, a spark discharge occurs between the discharge gaps of the spark plug 2, and as shown in FIG. 3 (E), the secondary coil 1b of the ignition coil, the spark plug 2, Through the secondary current i21.

  The second trigger signal is generated after the first trigger signal Vt1 is generated so that the second discharge switch 502 is turned on while the secondary current i21 flows (while the discharge continues). A delay time T2 until Vt2 is generated is set. When the second trigger signal Vt2 is applied to the second discharge switch 502, the second discharge switch 502 is turned on, so that the charge accumulated in the second ignition capacitor 501 is changed to the second discharge switch 502. The electric current is discharged through 502, the series circuit of the first primary coil 1a1 and the second primary coil 1a2, and a primary current ic2 flows as shown in FIG. Since the primary coil of the ignition coil that constitutes a part of the discharge circuit of the second ignition capacitor 501 is composed of two primary coils 1a1 and 1a2 connected in series with each other, its inductance is the first primary coil. It is larger than the inductance of 1a1 alone. Therefore, the peak value of the primary current ic2 that flows when the second ignition capacitor 501 is discharged is smaller than the peak value of the primary current ic1 that flows when the first ignition capacitor 401 is discharged. . In the process of decreasing the primary current ic2 past the peak, an induced voltage is generated in the primary coil 1a so as to prevent the current ic2 from decreasing. The induced voltage causes the flywheel current to pass through the flywheel diode 3 and the primary coil 1a. if2 (FIG. 3D) flows. When the primary current ic2 that rises quickly flows, the secondary current i22 rises as shown in FIGS. 2 (G) and 3 (E), and the time during which the secondary current flows through the ignition coil (discharge duration) is extended. .

  In the present embodiment, the primary coil constituting a part of the discharge circuit of the second ignition capacitor 501 is made by increasing the number of turns of the second primary coil 1a2 and increasing the inductance sufficiently. 5 can be made larger (about 2 to 5 times) than the inductance of the primary coil 1a of the ignition coil in the conventional ignition device shown in FIG. 5, so that the discharge circuit of the second ignition capacitor 501 The ratio R / L of the resistance R and the inductance L of the primary coil that constitutes a part of the coil can be reduced, and the discharge duration can be lengthened.

  When the capacitance of the second ignition capacitor is constant, the discharge duration T4 (FIGS. 2G and 3E) obtained by discharging the second ignition capacitor through the primary coils 1a1 and 1a2 is shown in FIG. In the conventional ignition device shown in FIG. 6, the discharge duration time T4 ′ (FIGS. 6G and 7E) obtained by discharging the second ignition capacitor 501 through the primary coil 1a can be significantly increased. Even if the capacitance of the ignition capacitor 501 is not particularly increased, the ignition spark discharge duration can be made sufficiently long to improve the ignition performance.

  In addition, since the inductance of the circuit that discharges the second ignition capacitor 501 can be increased, the peak value of the secondary current i22 that flows when the second ignition capacitor is discharged is reduced, and the average of the secondary currents is reduced. A value can be made small and the heat_generation | fever from a secondary coil can be decreased.

  In the capacitor discharge type ignition device, the voltage at both ends of the secondary coil 1b when spark discharge is generated in the spark plug 2 is about 2 KV. That is, after a spark discharge is generated between the gaps of the spark plug 2, in order to sustain the discharge, a voltage of 2 KV or more may be generated in the secondary coil of the ignition coil.

  As an example, when the charging voltage of the ignition capacitors 401 and 501 is 200 V, a primary current having a peak value of 60 A flows through the first primary coil 1a1 of the ignition coil. If a 20 KV (secondary no-load voltage) is induced in the secondary coil at this time, the primary coil 1a2 has a primary current flowing through the series circuit of the primary coils 1a1 and 1a2 when the ignition capacitor 501 is discharged so as to be 6A or more. If the impedance is set, the secondary coil 1b can generate a voltage of 2 KV or more necessary for maintaining the discharge at the spark plug 2.

  In the above embodiment, the first primary coil 1a1 and the second primary coil 1a2 are connected in series. However, as shown in FIG. 4, the first primary coil 1a1 and the second primary coil 1a2 are connected. Without being connected in series, the first ignition capacitor 401 is discharged through the first discharge switch 402 and the first primary coil 1a1, and the second ignition capacitor 501 is connected to the second discharge switch 502. The first and second ignition circuits 4 and 5 may be configured to discharge through the second primary coil 1a2.

In the example shown in FIG. 4, one end of the first primary coil 1a1 and one end of the second primary coil 1a2 are grounded, and the other end of the first primary coil 1a1 and the other end of the second primary coil 1a2. Are connected to one end of the first ignition capacitor 401 and one end of the second ignition capacitor 501, respectively, between the other end of the second ignition capacitor 401 and the ground, and to the other end of the second ignition capacitor 501. Thyristors Th1 and Th2 constituting the first discharge switch 402 and the second discharge switch 502, respectively, are connected between the grounds with their cathodes facing the ground side.
In this case, the second primary coil 1a2 has a sufficiently larger number of turns than the first primary coil 1a1 so that the second primary coil 1a2 has an inductance sufficiently larger than the inductance of the first primary coil 1a1. It is wound. The first flywheel diode 301 is connected in parallel to the first primary coil 1a1 of the ignition coil, and the second flywheel diode 302 is connected in parallel to the second primary coil 1a2 of the ignition coil. Has been.

  Also in the case of the configuration shown in FIG. 4, the number of turns of the first primary coil 1a1 is reduced to reduce its inductance, the number of turns of the second primary coil 1a2 is increased, and the inductance is sufficiently increased. The first primary coil and the second primary coil are connected in series, and the charge of the second ignition capacitor is discharged through the first primary coil and the second primary coil (see FIG. The same effect as in the case of (1) can be obtained.

  In each of the above embodiments, the first discharge switch and the second discharge switch are configured by thyristors, but these discharge switches may be switches having a self-holding function, and are not limited to thyristors. . For example, a switch having a function equivalent to that of a thyristor by combining two MOSFETs may be used as a discharge switch.

  In the embodiment described above, the exciter coil 6 and the diodes 7 to 9 constitute the capacitor charging power supply unit that generates a capacitor charging voltage. However, the configuration of the capacitor charging power supply unit is not limited to this. For example, the capacitor charging power supply unit may be configured by a battery and a DC / DC converter that boosts the terminal voltage of the battery to 2 hundred and several tens of volts. Further, a power supply for charging a capacitor by a power generation coil provided in a magnet generator driven by an engine, having a relatively small number of turns, a chopper circuit for boosting an induced voltage of the power generation coil, and a rectifier for rectifying the output of the chopper circuit The part can also be configured.

1 is a circuit diagram showing a configuration of a first exemplary embodiment of the present invention. FIG. 2 is a waveform diagram showing a voltage waveform and a current waveform of each part of the ignition device shown in FIG. 1. FIG. 2 is a waveform diagram showing waveforms of a current and a secondary current that flow on the primary side of an ignition coil of the ignition device shown in FIG. 1. It is the circuit diagram which showed the structure of the 2nd Embodiment of this invention. It is the circuit diagram which showed the structure of the conventional capacitor discharge type internal combustion engine ignition device. FIG. 6 is a waveform diagram showing a voltage waveform and a current waveform of each part of the conventional ignition device shown in FIG. 5. FIG. 6 is a waveform diagram showing waveforms of a current and a secondary current that flow on the primary side of the ignition coil of the conventional ignition device shown in FIG. 5.

Explanation of symbols

1 ignition coil 1a1 first primary coil 1a2 second primary coil 1b secondary coil 2 spark plug 301 first flywheel diode 302 second flywheel diode 4 first ignition circuit 401 first ignition capacitor 402 First discharge switch 5 Second ignition circuit 501 Second ignition capacitor 502 Second discharge switch 6 Exciter coil

Claims (3)

An ignition coil connected to a secondary side of an ignition plug attached to a cylinder of the internal combustion engine, a capacitor charging power source for generating a capacitor charging voltage, and the power source provided on the primary side of the ignition coil Are provided for each of the first and second ignition capacitors charged to one polarity by the output of the first output and the first and second ignition capacitors, and the first and second trigger signals are respectively given to the first and second ignition capacitors. The first and second discharge switches for discharging the electric charge accumulated in the first and second ignition capacitors through the primary side of the ignition coil and the ignition timing of the internal combustion engine. The first trigger signal is applied to the first discharge switch, and the second discharge scan is generated before the spark discharge generated in the spark plug due to the conduction of the first discharge switch disappears. The ignition device for capacitor discharge type internal combustion engine having an ignition timing control unit for the pitch giving the second trigger signal,
The ignition coil includes a first primary coil and a second primary coil connected in series to the first primary coil on a primary side,
The first discharge switch is provided so as to discharge the electric charge accumulated in the first ignition capacitor through the first primary coil when conducting.
The second discharge switch is provided to discharge the electric charge accumulated in the second ignition capacitor through a series circuit of the first primary coil and the second primary coil when conducting.
A first flywheel diode is connected in parallel with the first primary coil of the ignition coil, and in parallel with a series circuit of the first primary coil and the second primary coil of the ignition coil. The second flywheel diode is connected,
An ignition device for a capacitor discharge internal combustion engine. An ignition coil connected to a secondary side of an ignition plug attached to a cylinder of the internal combustion engine, a capacitor charging power source for generating a capacitor charging voltage, and the power source provided on the primary side of the ignition coil Are provided for each of the first and second ignition capacitors charged to one polarity by the output of the first output and the first and second ignition capacitors, and the first and second trigger signals are respectively given to the first and second ignition capacitors. The first and second discharge switches for discharging the electric charge accumulated in the first and second ignition capacitors through the primary side of the ignition coil and the ignition timing of the internal combustion engine. The first trigger signal is applied to the first discharge switch, and the second discharge scan is generated before the spark discharge generated in the spark plug due to the conduction of the first discharge switch disappears. The ignition device for capacitor discharge type internal combustion engine having an ignition timing control unit for the pitch giving the second trigger signal,
The ignition coil includes a first primary coil having one end grounded and a second primary coil having one end connected to the other end of the first primary coil and connected in series to the first primary coil. And the other end of the first primary coil and the other end of the second primary coil are connected to one end of the first ignition capacitor and one end of the second ignition capacitor, respectively. ,
The first discharge switch and the second discharge switch are connected between the other end of the first ignition capacitor and the ground, and between the other end of the second ignition capacitor and the ground, respectively.
A first flywheel diode having a cathode facing the ground side is connected between the other end of the first primary coil of the ignition coil and the ground, and between the other end of the second primary coil of the ignition coil and the ground. A second flywheel diode with the cathode facing the ground is connected to
An ignition device for a capacitor discharge internal combustion engine. An ignition coil connected to a secondary side of an ignition plug attached to a cylinder of the internal combustion engine, a capacitor charging power source for generating a capacitor charging voltage, and the power source provided on the primary side of the ignition coil Are provided for each of the first and second ignition capacitors charged to one polarity by the output of the first output and the first and second ignition capacitors, and the first and second trigger signals are respectively given to the first and second ignition capacitors. The first and second discharge switches for discharging the electric charge accumulated in the first and second ignition capacitors through the primary side of the ignition coil and the ignition timing of the internal combustion engine. The first trigger signal is applied to the first discharge switch, and the second discharge scan is generated before the spark discharge generated in the spark plug due to the conduction of the first discharge switch disappears. The ignition device for capacitor discharge type internal combustion engine having an ignition timing control unit for the pitch giving the second trigger signal,
The ignition coil includes a first primary coil and a second primary coil having a larger number of turns than the first primary coil on the primary side,
The first discharge switch is provided so as to discharge the electric charge accumulated in the first ignition capacitor through the first primary coil when conducting.
The second discharge switch is provided to discharge the electric charge accumulated in the second ignition capacitor through the second primary coil when conducting.
A first flywheel diode is connected in parallel to the first primary coil of the ignition coil, and a second flywheel diode is connected in parallel to the second primary coil of the ignition coil. Being
An ignition device for a capacitor discharge internal combustion engine.

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