JP2008025372A - Capacitor discharge type ignition device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitor discharge type ignition device for an internal combustion engine, preventing malfunction of a thyristor for discharge without sacrificing ignition performance in a high-speed rotation area of an engine so as to improve reliability. <P>SOLUTION: A DC-DC converter is used as a power source part charging a capacitor for ignition. An ignition position signal Vip is generated when an ignition position calculated by a microprocessor is detected. When the ignition position signal is generated, the thyristor for discharge is turned on to perform an ignition action. A pressure rising action stop command signal Va is generated at timing earlier than timing ti where the ignition position signal Vip is generated by a preset preceding time Tp, and the pressure rising action stop command signal Va is extinguished at timing extinguishing the ignition position signal Vip. By stopping the pressure rising action of the DC-DC converter while the pressure rising action stop command signal Va is generated, generation of the ignition position signal Vip is not generated while a charge current Ivc is passing through the capacitor for ignition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  A capacitor discharge type ignition device for an internal combustion engine includes an ignition coil, an ignition capacitor provided on a primary side of the ignition coil, and a turn-on when an ignition signal is given to connect the ignition capacitor to the primary coil of the ignition coil. An ignition circuit having a discharge thyristor for discharging through, a charging power supply unit for charging the ignition capacitor, and an ignition control unit for generating an ignition signal at the ignition position (crank angle position where the ignition operation is performed) of the internal combustion engine It consists of.

In this type of ignition device, when the ignition control unit generates an ignition signal, the discharge thyristor is turned on to discharge the charge of the ignition capacitor through the primary coil of the ignition coil, and a high voltage is applied to the primary coil of the ignition coil. Induce. Since this voltage is boosted by the step-up ratio between the primary and secondary of the ignition coil, a high voltage for ignition is induced in the secondary coil of the ignition coil. Since this high voltage is applied to a spark plug attached to the cylinder of the engine, a spark discharge is generated in the spark plug, and the engine is ignited. When the capacitance of the ignition capacitor C, the charging voltage of the ignition capacitor when the ignition operation is performed (the voltage across the ignition capacitor) and Vc, ignition energy P ^{is, P = C × Vc 2/} 2 Given in. Therefore, in order to obtain a predetermined ignition performance, it is necessary to charge the ignition capacitor until the charging voltage Vc of the ignition capacitor reaches a predetermined level before performing the ignition operation.

  The charging power source for charging the ignition capacitor includes an exciter coil provided in a magnet generator attached to the internal combustion engine and a rectifier for rectifying the AC output, and a battery output voltage (usually 12). [V]) includes a DC-DC converter that boosts the voltage by a booster circuit using a chopper circuit.

  Since it is necessary to increase the number of turns of the exciter coil, if the exciter coil is provided in the magnet generator, it is inevitable that the magnet generator attached to the engine will be increased in size. On the other hand, when a charging power supply unit composed of a DC-DC converter is employed, it is not necessary to provide an exciter coil having a large number of turns in the magnet generator, so that the magnet generator can be miniaturized.

  As an ignition device for a capacitor discharge type internal combustion engine using a charging power supply unit composed of a DC-DC converter, for example, there is one disclosed in Patent Document 1. The power supply unit for charging used in the ignition device disclosed in Patent Document 1 includes a step-up transformer in which the output voltage of the battery is applied to the primary coil, and a step-up transformer that conducts while the drive signal is applied and is connected from the battery. And a chopper switch circuit for supplying a primary current to the boost transformer, and when it is detected that the secondary current of the boost transformer is less than a predetermined threshold, When the primary current is passed and the primary current of the step-up transformer reaches the set value, the primary circuit of the step-up transformer is set so that the chopper switch circuit is cut off and a voltage is induced in the secondary coil of the step-up transformer. It comprises a DC-DC converter provided with a chopper switch control circuit for controlling the chopper switch circuit according to the current and the secondary current.

  In the ignition device disclosed in Patent Document 1, the DC-DC converter repeats the boost operation intermittently, and the ignition capacitor is charged stepwise by the voltage output from the converter every time the boost operation is performed. It will be done. Therefore, as shown in FIG. 4D, the charging current Ivc flows intermittently through the ignition capacitor, and as shown in FIG. 4C, the charging voltage of the ignition capacitor (the voltage across the ignition capacitor). Vc rises step by step. In the ignition device disclosed in Patent Document 1, the charging current Ivc flows through the ignition capacitor for the longest time T1 in the first step-up operation of the DC-DC converter performed at the start of charging of the ignition capacitor, and then the ignition capacitor. As the charging proceeds, the time during which the charging current Ivc flows when each boosting operation is performed becomes shorter.

  In the ignition device disclosed in Patent Document 1, in order to charge the ignition capacitor to a predetermined charging voltage, a voltage detection circuit for detecting the charging voltage of the ignition capacitor, and the ignition capacitor detected by the voltage detection circuit The boosting operation of the DC-DC converter is stopped when the charging voltage of the battery becomes equal to or higher than the set level Vcm, and the boosting operation of the DC-DC converter is restarted when the charging voltage of the ignition capacitor becomes lower than the set level. And a step-up operation control circuit for controlling the step-up operation of the DC-DC converter according to the charging voltage of the charging capacitor.

  In the ignition device disclosed in Patent Document 1, a voltage detection circuit including a resistor voltage divider is connected in parallel to the ignition capacitor, and the discharge circuit of the ignition capacitor is configured by this voltage detection circuit. The ignition capacitor is charged until its charge voltage Vc reaches the set level Vcm, and then is discharged little by little. When the charge voltage of the ignition capacitor falls below the set level due to this discharge, the DC-DC converter boosts. Operation resumes. Therefore, as shown in FIGS. 4C and 4D, the ignition capacitor is repeatedly charged and discharged, and the charge voltage Vc is maintained near the set level Vcm.

  In this type of ignition device, when the discharge thyristor is turned on in response to the ignition signal, if the current flows from the DC-DC converter to the discharge thyristor, the discharge thyristor cannot be turned off. Therefore, in the ignition device disclosed in Patent Document 1, in order to ensure that the discharge thyristor is turned off, the boost operation stop command signal Va (FIG. 4B) is set for a set time Ta when the ignition signal Vi is generated. And a step-up operation stop circuit for stopping the step-up operation of the DC-DC converter by keeping the chopper switch off while the step-up operation stop command signal Va is generated. When the ignition signal is generated, the boost operation of the DC-DC converter is stopped for a set time Ta (while the boost operation stop command signal is generated). The signal width (set time) Ta of the boosting operation stop command signal is set to a time (for example, 10 μsec) slightly longer than the time required to completely discharge the charge of the ignition capacitor in the fully charged state.

  When the ignition capacitor is not recharged immediately before the ignition signal Vi is generated, the boost operation stop command signal is generated as described above, and the charge of the ignition capacitor is increased after the ignition signal is generated. If the boost operation of the DC-DC converter is stopped until the discharge is completed, the discharge thyristor can be reliably turned off when the discharge of the ignition capacitor is completed. The capacitor can be charged and the ignition operation can be performed without any trouble.

  However, as described below, when the ignition capacitor is recharged just before the ignition signal Vi occurs (just before the boost operation stop command signal is generated), the discharge thyristor fails to turn off. As a result, the ignition operation stops and the engine may stall.

  That is, as shown in FIG. 4, the ignition capacitor is recharged immediately before the ignition signal Vi is generated at the ignition timing ti (immediately before the boost operation stop command signal is generated). If the ignition signal Vi is generated while the recharging current Ivc flows through the capacitor, when the discharging thyristor is turned on, the recharging current that has been flowing through the ignition capacitor flows into the discharging thyristor. Therefore, as shown in FIG. 4E, the anode current Isi flows through the discharging thyristor for a long time. When the ignition signal Vi disappears, the boost operation stop command signal Va disappears, and the DC-DC converter starts the boost operation. At this time, the current Isi is still flowing through the thyristor, and the thyristor is in the ON state. Therefore, the current flows from the DC-DC converter to the thyristor, and the thyristor cannot be turned off. Although the DC-DC converter intermittently performs the boosting operation, the period during which the boosting operation is paused is extremely short. Therefore, the discharge thyristor cannot be turned off while the DC-DC converter pauses the boosting operation. When such a condition occurs, the ignition capacitor is no longer charged, so the ignition operation is not performed and the engine stalls.

In order to solve the above problem, the energy stored in the secondary coil of the step-up transformer of the DC-DC converter is completely discharged through the discharge thyristor by the step-up operation performed immediately before the ignition signal Vi is generated. The boost operation stop command signal Va may be continuously generated until the anode current flowing through the discharge thyristor becomes less than the holding current.
JP-A-9-209893

  As described above, in the ignition apparatus for a capacitor discharge type internal combustion engine disclosed in Patent Document 1, even when the ignition capacitor is recharged immediately before the ignition signal Vi is generated, the discharge thyristor is reliably turned off. Therefore, it is necessary to continue generating the boosting operation stop command signal Va until the current Isi flowing through the discharging thyristor is attenuated to be less than the holding current of the thyristor.

  However, when the signal width of the boosting operation stop command signal is set to be long in this way, the start of charging of the ignition capacitor is delayed, so that the time for performing one combustion cycle of the internal combustion engine is shortened at the time of high-speed rotation of the engine. There is a problem that the ignition capacitor cannot be sufficiently charged, and the ignition performance at high-speed rotation is lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition device for a capacitor discharge type internal combustion engine that uses a DC-DC converter that performs a step-up operation by intermittently passing a primary current of a step-up transformer with a chopper switch as a power supply unit for charging an ignition capacitor. An object of the present invention is to improve reliability by eliminating the possibility of the discharge thyristor failing to turn off without sacrificing ignition performance during high-speed rotation.

  The present invention relates to a DC-DC converter that boosts the output voltage of a battery, an ignition coil, and an ignition coil that is provided on the primary side of the ignition coil and is charged stepwise by a voltage intermittently output from the DC-DC converter. A capacitor, an ignition control unit that generates an ignition signal at the ignition position of the internal combustion engine, a discharge thyristor that is turned on when the ignition signal is generated and discharges the charge accumulated in the ignition capacitor through the primary coil of the ignition coil; , A voltage detection circuit comprising a resistance voltage dividing circuit connected in parallel to the ignition capacitor, and when the charging voltage of the ignition capacitor detected by the voltage detection circuit exceeds a set level, the DC-DC converter When the boosting operation is stopped and the charging voltage of the ignition capacitor falls below the set level, the DC-DC converter boosting operation is started. Set to ensure that the boost operation control circuit controls the boost operation of the DC-DC converter according to the charging voltage of the charging capacitor so as to open and the time for turning off the discharge thyristor turned on in response to the ignition signal Capacitor having a boosting operation stop command signal generating means for generating a boosting operation stop command signal for a time, and a boosting operation stop circuit for stopping the boosting operation of the DC-DC converter while the boosting operation stop command signal is generated The subject is an ignition device for a discharge internal combustion engine.

  In the ignition device for a capacitor discharge internal combustion engine targeted by the present invention, the DC-DC converter is electrically connected to a step-up transformer in which the output voltage of the battery is applied to the primary coil while a drive signal is applied. A step-up circuit including a chopper switch circuit for flowing a primary current from the battery to the step-up transformer, and the chopper switch circuit is turned on when it is detected that the secondary current of the step-up transformer is less than a predetermined threshold value. When the primary current flows through the step-up transformer and the primary current of the step-up transformer is detected to reach the set value, the chopper switch circuit is turned off to induce a voltage in the secondary coil of the step-up transformer. A chopper switch control circuit for controlling the chopper switch circuit in accordance with the primary current and secondary current of the step-up transformer. It is used.

  In the present invention, the boosting operation stop command signal generation means generates a boosting operation stop command signal at a timing preceding the timing at which the ignition signal is generated by a set preceding time, and is used for ignition performed through a discharge thyristor. The boosting operation stop command signal is extinguished at a timing immediately after the capacitor discharge is completed.

  For the preceding time, a set margin time is added to the time when the charging current flows from the DC-DC converter that resumes the boost operation when the voltage across the ignition capacitor becomes lower than the set level to the ignition capacitor. It is preferable to set it equal to time.

  As described above, if the boost operation stop command signal is generated at a timing preceding the set preceding time by the timing at which the ignition signal is generated, the DC-DC converter re-applies from the DC-DC converter to the ignition capacitor at a low engine speed. Since it is possible to prevent an ignition signal from being applied to the discharging thyristor while the charging current is flowing, when the discharging thyristor is turned on in response to the ignition signal, current is supplied from the DC-DC converter to the discharging thyristor. It can be prevented from flowing. Therefore, even if the boosting operation stop command signal is extinguished immediately after the completion of the discharge of the ignition capacitor, the discharge thyristor can be reliably turned off.

  As described above, when the boosting operation stop command signal is generated at a timing that is earlier than the timing at which the ignition signal is generated, a recharge current flows from the DC-DC converter to the ignition capacitor. In such a way that no ignition signal is generated while the discharge thyristor is turned on in response to the ignition signal, current is prevented from flowing into the discharge thyristor from the DC-DC converter side. Therefore, even after the discharge of the ignition capacitor is completed (after the ignition operation is performed), the discharge thyristor cannot be turned off at the time of low-speed engine rotation even if the boost operation stop command signal is quickly extinguished. There is no. Therefore, after the ignition operation is performed, charging of the ignition capacitor can be started without delay, and it is possible to prevent a shortage of time for charging the ignition capacitor during high-speed rotation of the engine.

  As described above, according to the present invention, the boost operation stop command signal is generated from the DC-DC converter to the ignition capacitor at a timing that is earlier than the timing at which the ignition signal is generated. Since a state in which an ignition signal is given to the discharge thyristor does not occur while the charging current is flowing, when the discharge thyristor is turned on in response to the ignition signal, the DC-DC converter side It is possible to prevent a situation in which a current flows through the thyristor and the discharge thyristor cannot be turned off, and even if the boost operation stop command signal is extinguished immediately after the ignition capacitor discharge is completed, the discharge thyristor Turn-off can be performed reliably. Accordingly, the thyristor can be reliably turned off without delaying the timing of starting charging of the ignition capacitor, and the reliability of the operation of the ignition device can be achieved without sacrificing the ignition performance during high-speed rotation of the engine. Can be increased.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention. The hardware configuration of the ignition device according to this embodiment is the same as that of the ignition device disclosed in Patent Document 1. In FIG. 1, 1 is an ignition circuit, 2 is a power supply unit for charging, 3 is an ignition control unit having a microprocessor, 4 is a voltage detection circuit, 5 is a boost operation control circuit, 6 is a boost operation stop circuit, and 7 is a constant voltage. It is a power supply circuit. The configuration of each part will be described below.

  The ignition circuit 1 is connected to an ignition coil IG having a primary coil L1 and a secondary coil L2, an ignition capacitor Ci provided on the primary side of the ignition coil, and an ignition capacitor Ci when an ignition signal Vi is applied. A known capacitor discharge type circuit comprising a discharge thyristor Si for discharging the electric charge through the primary coil L1 of the ignition coil and an ignition plug P attached to the cylinder of the engine and connected to the secondary coil L2 of the ignition coil It is.

  Although there are various modifications to the specific configuration of the capacitor discharge ignition circuit, the configuration of the illustrated circuit will be described in more detail. In this example, one end of the primary coil L1 of the ignition coil IG is grounded, and the primary One end of an ignition capacitor Ci is connected to the other end of the coil. A thyristor Si is connected between the other end of the capacitor Ci and the ground with the cathode facing the ground side, and a resistor Ri is connected between the gate and cathode of the thyristor Si. A diode Di having a cathode facing the ground side is connected to both ends of the primary coil L1 of the ignition coil IG. One end of the secondary coil L2 of the ignition coil IG is commonly connected to the other end of the primary coil L1, and the other end of the secondary coil L2 is connected to a non-ground side terminal of an ignition plug P attached to the cylinder of the engine. .

  The charging power supply unit 2 includes a battery 2A having a negative electrode grounded, and a DC-DC converter that boosts the voltage of the battery. The DC-DC converter includes a booster circuit 2D including a booster transformer 2B and a chopper switch circuit 2C, and a chopper switch control circuit 2J.

  The chopper switch control circuit 2J includes a chopper drive command signal generation circuit 2E, a differentiation control switch circuit 2F, a differentiation circuit 2G, a drive signal supply circuit 2H, a cutoff command signal generation circuit 2K, and a switch cutoff control circuit 2L. It is comprised by.

  In this example, the voltage across the battery 2A (usually 12 [V]) is input to the constant voltage power supply circuit 7 through the power switch SW, and a substantially constant DC voltage Vcc obtained from the constant voltage power supply circuit 7 is applied to each part. Applied to the power supply terminal. Although not shown, the battery 2A is charged through a predetermined charging circuit by the output of a charging coil provided in a magnet generator attached to the internal combustion engine.

  The step-up transformer 2B is obtained by winding a primary coil W1 and a secondary coil W2 around a ferrite core, and one end of the primary coil W1 is connected to the positive terminal of the battery 2A. The other end of the primary coil W1 is connected to the drain of an FET (Field Effect Transistor) F1, and the source of the FET F1 is grounded through a primary current detection resistor R20. Df is a parasitic diode existing between the drain and source of the FET.

  One end of a resistor R1 is connected to the gate of the FET F1, and the other end of the resistor is connected to a common connection point between the emitter of the NPN transistor TR1 and the emitter of the PNP transistor TR2. The collector of the transistor TR1 is connected to the positive terminal of the battery 2A through the power switch SW, and the collector of the transistor TR2 is grounded. The bases of the transistors TR1 and TR2 are connected in common, and a resistor R2 is connected between the common connection point of the bases of both transistors and the collector of the transistor TR1.

  In this example, transistors TR1 and TR2 and resistors R1 and R2 constitute a drive circuit for driving FET F1, and the drive circuit and FET F1 constitute a chopper switch circuit 2C. In the chopper switch circuit 2C, the common connection point of the bases of the transistors TR1 and TR2 serves as an input terminal for the drive signal, and the drive signal Vd having a positive polarity (rising to a positive potential with respect to the ground) is connected to the input terminal. Is applied, the transistor TR2 is cut off and the transistor TR1 is turned on. When the transistor TR1 becomes conductive, the drive signal Vg is given to the FET F1 from the battery 2A side through the switch SW, the collector-emitter of the transistor TR1, and the resistor R1. The FET F1 conducts while the drive signal Vg is applied (while the drive signal Vd is generated), and causes a primary current to flow through the step-up transformer 2B.

  One end of the secondary coil W2 of the step-up transformer 2B is connected through a diode D1 to a connection point between the ignition capacitor Ci and the anode of the thyristor Si. On the other end side of the secondary coil W2 of the step-up transformer, a charging current detection diode D2 having an anode grounded is provided. The diode D2 is connected in series to the secondary coil W2 of the step-up transformer, and the base of the drive command signal generating transistor TR3 whose emitter is grounded is connected to the cathode of the diode D2. Resistors R3 and R4 are connected between the collector of the transistor TR3 and the output terminal of the constant voltage power supply circuit 7, and between the base of the transistor TR3 and the output terminal of the constant voltage power supply circuit 7, respectively. Is connected to a resistor R5. In this example, a diode D2, a transistor TR3, and resistors R3 to R5 constitute a chopper drive command signal generation circuit 2E.

  The base of the transistor TR4 for differential control is connected to the collector of the transistor TR3, and a resistor R6 is connected between the base and emitter of the transistor TR4. In this example, the transistor TR4 and the resistor R6 constitute a differential control switch circuit 2F.

  The collector of the differential control transistor TR4 is connected to one end of a differential capacitor C1, and the other end of the capacitor C1 is connected to the base of a differential pulse generating transistor TR5 whose emitter is grounded through a resistor R7b. A diode D3 having an anode directed to the ground side and a resistor R15 are connected in parallel between the base and emitter of the transistor TR5, and a resistor R7a is connected between one end of the differential capacitor C1 and the output terminal of the power supply circuit 7. . In this example, a differentiating circuit 2G is constituted by a differential capacitor C1, a differential pulse generating transistor TR5, a diode D3, and resistors R7a to R7b and R15.

  The drive signal supply circuit 2H includes an NPN transistor TR6 whose emitter is grounded, a resistor R8 connected between the base of the transistor TR6 and the output terminal of the power supply circuit 7, and a resistor connected between the base emitter of the transistor TR6. R9, and the collector and emitter of the transistor TR5 are connected to the base and emitter of the transistor TR6, respectively. The collector of the transistor TR6 is connected to the drive signal input terminal (bases of the transistors TR1 and TR2) of the chopper switch circuit 2C.

  In this example, the differential control switch circuit 2F and the differential circuit 2G constitute a drive pulse generation circuit that is triggered when a chopper drive command signal is generated and generates a pulse having a predetermined time width as the drive pulse Vd '. Has been. The drive signal supply circuit 2H inverts the polarity of the drive pulse Vd 'and supplies it as the drive signal Vd to the drive signal input terminal of the chopper switch circuit 2C.

  The voltage V20 across the primary current detection resistor R20 is input to the inverting input terminal of the comparison circuit CP1 through the resistor R21. A reference voltage Vr1 obtained by dividing the output voltage Vcc of the constant voltage power supply circuit 7 by a voltage dividing circuit composed of a series circuit of resistors R22 and R23 is input to the non-inverting input terminal of the comparison circuit CP1. The output terminal of the comparator circuit CP1 is connected to the gate of a programmable unijunction transistor (PUT) Pu1 whose cathode is grounded, and the anode of the PUT is connected to the connection point between the differential capacitor C1 and the resistor R7b. A resistor R24 is connected between the anode gates of PUT Pu1.

  In this example, when the primary current detection resistor R20, resistors R21 to R23, and the comparison circuit CP1 detect the primary current of the step-up transformer 2B and detect that the primary current has reached the set value. A cutoff command signal generation circuit 2K that generates a cutoff command signal Voff is configured. Further, the PUT Pu1 and the resistor R24 provide a switch cutoff control circuit 2L that prevents the drive signal Vd from being applied to the chopper switch circuit when the cutoff command signal Voff is generated and puts the chopper switch circuit in the cutoff state. It is configured.

  The ignition control unit 3 includes a signal coil 3A, a microprocessor (MPU) 3B that calculates the ignition position of the internal combustion engine using the output of the signal coil 3A as an input, and an ignition signal output circuit 3C.

  The signal coil 3A is provided in a signal generator (not shown) attached to the engine, and the first signal Vs1 and the second signal having a pulse waveform at the reference crank angle position and the minimum advance angle position of the engine, respectively. The signal Vs2 is generated. The first signal Vs1 is at a position sufficiently advanced with respect to the crank angle position (top dead center position) when the piston of the engine reaches top dead center (position advanced further than the maximum advance angle position). The signal is generated at the set reference crank angle position, and the second signal Vs2 is generated at the minimum advance angle position set at the crank angle position delayed from the reference crank angle position. The first signal Vs1 generated at the reference crank angle position sufficiently advanced from the top dead center position is used as a reference signal for determining the position at which the measurement of the ignition position of the engine is started.

  The microprocessor 3B uses the rotation angle information obtained from the first signal (reference signal) Vs1 and the second signal Vs2 and the rotation speed information, and the ignition position at each rotation speed (crank angle position that performs the ignition position). Is calculated. This ignition position is calculated as an advance angle from the top dead center position. The microprocessor generates an ignition position signal Vip (FIG. 2A) having a waveform that falls from a high level (H level) to a low level (L level) when it detects that the crank angle position of the engine matches the calculated ignition position. Output.

  In the present embodiment, the signal width of the ignition position signal Vip is slightly smaller than the time required to completely discharge the charge accumulated in the ignition capacitor Ci through the discharge thyristor Si and the primary coil L1 of the ignition coil. Set long (for example, about 10 μsec).

  The ignition signal output circuit 3C is a circuit that outputs an ignition signal Vi when the microprocessor 3B outputs the ignition position signal Vip. The emitter is connected to the output terminal of the constant voltage power supply circuit 7, and the base is the ignition of the microprocessor 3B. A PNP transistor TR7 connected to the position signal output port, a resistor R11 having one end connected to the collector of the transistor TR7, and a diode D4 having an anode connected to the other end of the resistor R11, the cathode of the diode D4 being The ignition signal output terminal is connected to the gate of the thyristor Si of the ignition circuit 1 (ignition signal input terminal of the ignition circuit).

  When the microprocessor 3B of the ignition position control unit lowers the potential of the ignition position signal output port to L level and outputs the ignition position signal Vip, the transistor TR7 becomes conductive, the emitter collector of the transistor TR7, the resistor R11 and the diode D4. And an ignition signal Vi as shown in FIG. The rising position of the ignition signal Vi becomes the ignition position of the engine. The waveform of the ignition signal Vi is a waveform obtained by inverting the waveform of the ignition position signal Vip.

  The voltage detection circuit 4 includes a series circuit of resistors R12 and R13 connected between the connection point of the ignition capacitor Ci and the anode of the thyristor Si and the ground, and a resistor R14 having one end connected to the connection point of the resistors R12 and R13. An output voltage V4 corresponding to the charging voltage of the capacitor Ci (terminal voltage of the capacitor Ci) is generated between the other end of the resistor R14 and the ground.

  The step-up operation control circuit 5 includes a reference voltage generation circuit 5A that generates a constant reference voltage Vr2 that gives a set level Vcm of the charging voltage of the ignition capacitor, and an output of the voltage detection circuit 4 that is proportional to the charging voltage Vc of the ignition capacitor. The comparison circuit CP2 in which the voltage V4 and the reference voltage Vr2 are input to the non-inverting input terminal and the inverting input terminal, respectively, and the resistor R32 connected between the output terminal of the comparison circuit CP2 and the output terminal of the constant voltage power supply circuit 7 The base of the comparator circuit CP2 is connected through a resistor R33, the emitter of which is grounded, and the resistor R34 connected between the base of the transistor TR8 and the ground. The collector of the transistor TR8 is connected to the connection point between the differential capacitor C1 and the resistor R7a. The reference voltage generation circuit 5A is composed of a series circuit of resistors R30 and R31 connected between the output terminals of the constant voltage power supply circuit 7, and divides the power supply voltage Vcc and outputs a reference voltage Vr2.

  The boosting operation stop circuit 6 has an NPN transistor TR9 whose collector is connected to a connection point between the differential capacitor C1 and the resistor R7a, an emitter grounded, a resistor R35 connected between the base emitter of the transistor TR9, and a transistor TR9. The resistor R36 has one end connected to the base, and the resistor R37 connected between the other end of the resistor R36 and the output terminal of the constant voltage power supply circuit 7. The base of the transistor TR9 is a boost operation of the microprocessor 3B. It is connected to the stop command signal output port.

  The microprocessor 3B of the ignition control unit 3 executes a predetermined program, thereby generating a boost operation stop command signal Va at a timing that is a set preceding time Tp before the timing at which the ignition signal Vi is generated. A stop command signal generating means is configured.

  As shown in FIG. 2, the boosting operation stop command signal generating means generates the boosting operation stop command signal Va at a timing before the set preceding time Tp from the timing ti at which the ignition signal Vi is generated ( The boost operation stop command signal Va is extinguished at a timing immediately after the timing of completion of the discharge of the ignition capacitor Ci performed through the discharge thyristor Si turned on in response to the ignition signal Vi (L level). To be configured). As will be described later, the preceding time Tp is set to a length necessary to extinguish the charging current flowing from the DC-DC converter to the ignition capacitor until the ignition signal is generated.

  In the present embodiment, the ignition position signal Vip is generated at the ignition position (becomes L level), and is extinguished (at H level) immediately after the completion of the discharge of the ignition capacitor Ci. Since the signal width of Vip (signal width of the ignition signal Vi) is set, the boost operation stop command signal Va is extinguished at the same time that the ignition position signal Vip disappears.

  The step-up operation stop command signal Va is inputted to the base of the transistor TR9 through the resistor R36, and the transistor TR9 is kept on while the step-up operation stop command signal Va is generated.

  When the engine is started, the microprocessor is initialized. At the time of initialization, the microprocessor outputs a boosting operation stop command signal Va.

  Next, operation | movement of the ignition device of this embodiment is demonstrated. In the ignition device of FIG. 1, it is assumed that the charge of the differential capacitor C1 is zero in a state where the power switch SW is open. When the power switch SW is open, the transistors TR1 to TR6 are in the cut-off state and the FET F1 is in the cut-off state, so that the step-up transformer 2B stops generating the voltage.

  When the power switch SW is turned on, the constant voltage power supply circuit 7 generates the voltage Vcc, and the voltage Vcc is applied to the chopper drive command signal generation circuit 2E. At this time, no current flows through the secondary coil W2 of the step-up transformer 2B, and no forward voltage drop occurs across the diode D2, so that the transistor TR3 is conductive and the transistor TR4 is in the cut-off state. At this time, since the power supply voltage Vcc is applied between the base and emitter of the transistor TR5 through a series circuit of the resistor R7a, the differential capacitor C1 and the resistor R7b, the charging current flowing from the constant voltage power supply circuit 7 to the differential capacitor C1 through the resistors R7a and R7b. Flows as a base current in the transistor TR5. Since the transistor TR5 conducts only while the charging current of the differential capacitor C1 flows, a drive pulse Vd 'falling from a high potential to almost zero potential is generated between the collector and emitter of the transistor TR5. Since the transistor TR6 is cut off only while the drive pulse Vd 'is generated (while the transistor TR5 is conducting), this corresponds to an inversion of the drive pulse Vd' between the collector and emitter of the transistor TR6. A drive signal Vd is generated. Since the transistor TR2 is in the cut-off state while the drive signal Vd is generated (while the transistor TR6 is cut off), the drive signal Vg is given to the FET F1 through the collector-emitter of the transistor TR1 and the resistor R1. As a result, the FET F1 becomes conductive, and a primary current flows through the step-up transformer 2B.

  When the primary current of the step-up transformer 2B reaches the set value, the voltage across the primary current detection resistor R20 reaches the set value, and the voltage V20 input to the inverting input terminal of the comparison circuit CP1 exceeds the reference voltage Vr1, The potential of the output terminal of the comparator circuit CP1 becomes the ground potential. Thereby, PUT Pu1 becomes conductive. When PUT Pu1 is conducted, the base current flowing to the transistor TR5 through the differential capacitor C1 and the resistor R7b is bypassed from the transistor TR5, so that the transistor TR5 is cut off. When the transistor TR5 is cut off, the transistor TR6 becomes conductive (the drive signal Vd disappears), so that the transistor TR2 becomes conductive and the drive signal Vg of the FET F1 disappears.

  In the illustrated example, the magnitude of the primary current flowing through the step-up transformer 2B when the FET F1 of the chopper switch circuit is cut off causes the magnetic flux flowing through the core of the transformer 2B to be close to the saturation value. Thus, it is preferable to set the set value of the primary current (so as not to make the saturation value).

  The pulse width (time width) of the drive signal Vd given from the differentiating circuit 2G to the chopper switch circuit 2C through the drive signal supply circuit 2H is based on the time from when the primary current starts to flow to the step-up transformer until the set value is reached. Also set to a long time. The pulse width of the drive signal Vd can be appropriately set by adjusting the time constant determined by the resistance values of the resistors R7a and R7b of the differentiating circuit 2G and the capacitance of the capacitor C1.

  When the drive signal Vd disappears, the supply of the drive signal Vg to the FET F1 is stopped, so that the FET F1 is cut off and the primary current of the step-up transformer 2B is cut off. As a result, a high voltage is induced in the secondary coil W2 of the step-up transformer 2B, and this voltage is applied to the ignition circuit 1 through the diode D1. At this time, the charging current flows through the ignition capacitor Ci through the path of the secondary coil W2, the diode D1, the ignition capacitor Ci, the diode Di, and the primary coil L1 of the ignition coil, the diode D2, and the secondary coil W2, and the ignition capacitor Ci It is charged to the polarity shown.

  When the charging current of the ignition capacitor Ci flows, a forward voltage drop (maximum of about 0.6 volts) Vak occurs across the charging current detection diode D2. This voltage drop reversely biases the base and emitter of the transistor TR3, so that the transistor TR3 is cut off and the transistor TR4 is turned on.

  When the transistor TR4 is turned on, the charge of the differential capacitor C1 is discharged through the path of the differential capacitor C1 → the collector-emitter of the transistor TR4 → the diode D3 → the resistor R7b → the differential capacitor C1. When the charging current flowing from the secondary coil W2 of the step-up transformer to the ignition capacitor Ci becomes less than a predetermined threshold value (substantially becomes zero) and the forward voltage drop across the diode D2 becomes less than a predetermined level, Since the transistor TR3 is turned on, the transistor TR4 is turned off. Since the charging current flows through the differential capacitor C1 at the same time as the transistor TR4 is cut off, the drive pulse Vd 'is generated from the differential circuit 2G, and the drive signal Vd is supplied from the drive signal supply circuit 2H to the chopper switch circuit 2C.

  When the drive signal Vd is generated, the drive signal Vg is applied to the FET F1 and the FET is turned on, so that a primary current flows through the step-up transformer 2B. When the primary current of the step-up transformer reaches the set value and the drive signal Vd disappears, the FET F1 is cut off, and the primary current of the step-up transformer is cut off, and the secondary coil W2 of the step-up transformer has 200 tens of volts. A boosted voltage is induced.

  Thereafter, the same operation is repeated, and whenever a voltage is induced in the secondary coil of the step-up transformer 2B, a charging current flows through the ignition capacitor Ci, and as shown in FIG. 2 (D), both ends of the ignition capacitor Ci. Voltage gradually increases.

  As shown in FIG. 2 (E), as the charging of the ignition capacitor Ci proceeds, the time during which the charging current Ivc flows through the capacitor Ci is shortened, so that the drive applied to the gate of the FET F1. The generation interval of the signal Vg becomes shorter. Accordingly, the charging interval of the ignition capacitor Ci decreases as the charging of the capacitor proceeds, and the charging voltage Vc of the capacitor Ci increases as shown in FIG.

  When the charging voltage Vc of the ignition capacitor Ci becomes equal to or higher than the set level Vcm, the output voltage V4 of the voltage detection circuit 4 becomes higher than the reference voltage Vr2, so that the potential of the output terminal of the comparison circuit CP2 becomes high level. As a result, the transistor TR8 becomes conductive, and one end of the differential capacitor C1 is kept substantially at the ground potential. Therefore, the differentiating circuit 2G does not generate the pulse signal Vd ', and the boosting operation of the boosting circuit 2D is stopped. However, the charging of the ignition capacitor with the output voltage of the DC-DC converter that has already been generated is continued. Is charged to a level slightly higher than the set level Vcm.

  After charging of the ignition capacitor Ci is completed once in this way, the charge of the ignition capacitor Ci is discharged with a constant time constant through the resistors R12 and R13 of the voltage detection circuit 4, so that the charging voltage of the ignition capacitor Ci is Decreases at a constant rate. When the charging voltage Vc of the ignition capacitor Ci becomes less than the set level Vcm, the potential of the output terminal of the comparison circuit CP2 becomes low level (L level), so that the transistor TR8 is turned off, and the drive signal Vg to the FET F1 Supply resumed. As a result, the FET is turned on, the boosting operation is resumed, and the ignition capacitor Ci is recharged. Due to this recharging, the charging voltage of the ignition capacitor Ci becomes equal to or higher than the set level Vcm, so that the potential of the output terminal of the comparison circuit CP2 becomes high, the transistor TR8 becomes conductive, and the boosting operation of the boosting circuit 2D is performed. Although it stops, charging of the ignition capacitor is continued by the output voltage of the DC-DC converter already generated, and the ignition capacitor is charged to a level slightly higher than the set level Vcm. As described above, the discharging and recharging of the ignition capacitor are repeated, and the charging voltage of the ignition capacitor Ci is maintained near the set level Vcm.

  The time Tn ′ during which the recharging current flows through the ignition capacitor Ci is substantially equal to the time Tn during which the charging current Ivc flows through the ignition capacitor immediately before the ignition capacitor is completely charged. Tn ′ and Tn are, for example, about 10 μsec.

  The ignition control unit 3 generates a boost operation stop command signal Va at a timing tp which is set by the preceding time Tp set before the timing at which the ignition position signal Vip is generated, and at the same time extinguishes the ignition position signal Vip and stops the boost operation. The command signal Va is extinguished. Since the transistor TR9 is conductive while the boosting operation stop command signal Va is generated, one end of the differential capacitor C1 is kept at the ground potential to prevent the differential circuit from generating the drive pulse Vd '.

  In the example shown in FIG. 2, since the recharging of the ignition capacitor is completed before the boost operation stop command signal Va is generated, the ignition capacitor is switched while the boost operation stop command signal Va is generated. Charging is never performed.

  When the ignition control unit 3 generates the ignition position signal Vip at the ignition position of the internal combustion engine, the ignition signal output circuit 3C outputs the ignition signal Vi. Since this ignition signal is given to the discharge thyristor Si, the thyristor Si is turned on to discharge the charge of the capacitor Ci through the primary coil L1 of the ignition coil IG. As a result, a high voltage for ignition is generated in the secondary coil L2 of the ignition coil IG, a spark is generated in the spark plug P, and the engine is ignited.

  In the example shown in FIG. 2, since the output of the DC-DC converter 2 is stopped when the ignition signal Vi is generated, the discharge thyristor from the DC-DC converter side when the discharge thyristor is turned on. No current flows into Si. Therefore, the discharge thyristor Si is turned off when the charge of the ignition capacitor Ci is completely discharged and the anode current becomes less than the holding current.

  In the above description, it is assumed that when the boost operation stop command signal Va is generated, the recharging of the ignition capacitor Ci has already been completed, and no charging current flows from the DC-DC converter 2 to the ignition capacitor Ci. Assuming that the boost operation stop command signal Va is generated while the step-up transformer 2B primary current of the DC-DC converter is flowing, the primary current of the boost transformer is cut off at the moment when the boost operation stop command signal is generated. Therefore, a voltage is induced in the secondary coil of the step-up transformer, and a charging current flows through the ignition capacitor Ci due to this voltage. In this case, the entire period during which the charging current Ivc flows from the DC-DC converter 2 to the ignition capacitor Ci overlaps a part of the preceding time Ta of the boost operation stop command signal Va. Even in such a state, the preceding time Tp that determines the generation timing of the boost operation stop command signal Va is such that no charging current flows from the DC-DC converter 2 to the ignition capacitor Ci when the ignition signal Vi is generated. Need to be set long enough. However, if the preceding time Tp is set too long, charging of the ignition capacitor may not be completed during high-speed rotation of the engine.

  Therefore, it is preferable to set the preceding time Tp to the minimum necessary length. In this embodiment, after the charge of the ignition capacitor Ci is once completed, the charge of the ignition capacitor is discharged through the resistor of the voltage detection circuit 4 and the charge voltage Vc of the ignition capacitor is set to the preceding time Tp. It is set equal to a time obtained by adding a set margin time Tα to a time Tn ′ in which the charging current flows from the DC-DC converter that has resumed the step-up operation to the ignition capacitor when it becomes less than the set level Vcm.

  The time Tn ′ during which the charging current flows from the DC-DC converter 2 that has resumed the step-up operation to the ignition capacitor Ci when the voltage across the ignition capacitor becomes less than the set level Vcm is, for example, about 10 μsec. In this case, the margin time Tα is set to about 10 μsec. The signal width of the ignition signal Vi is set to about 10 μsec. In this case, the signal width Ta of the boosting operation stop command signal is about 30 μsec. The margin time Tα is not necessarily equal to Tn ′.

  These specific numerical values are merely examples, and the preceding time Tp, the margin time Tα, and the signal width of the ignition signal can take various values depending on circuit constants and the like.

  As in this embodiment, the ignition signal Vi is extinguished at a timing immediately after the completion of the discharge of the ignition capacitor Ci, and simultaneously with the extinction of the ignition position signal Vip, the boost operation stop command signal Va is If it is made to disappear, the program for controlling generation | occurrence | production and extinction of pressure | voltage rise operation stop command signal Va can be simplified.

  However, the present invention is not limited to such a configuration, and the ignition position signal Vip is extinguished at a timing prior to the completion of the discharge of the charge of the ignition capacitor, and is performed through the discharge thyristor Si. The boosting operation stop command signal Va may be extinguished at a timing slightly delayed from the timing at which the discharge of the charge of the ignition capacitor is completed (timing slightly delayed from the timing at which the ignition signal Vi disappears). .

  As described above, when the boosting operation stop command signal Va is generated before the ignition signal is generated, a state in which the ignition signal Vi is generated while the recharging current Ivc of the ignition capacitor Ci is flowing occurs. Therefore, the recharging current of the ignition capacitor flows into the discharge thyristor Si, preventing an abnormal situation in which the turn-off of the discharge thyristor is delayed or the discharge thyristor cannot be turned off. it can.

  In this embodiment, an algorithm of a task to be executed by the microprocessor of the ignition control unit 3 to constitute an ignition position signal generating means for generating an ignition position signal and a boosting operation stop command signal generating means for generating a boosting operation stop command signal A flow chart showing an example of this is shown in FIG. The task of FIG. 3 coincides with the set count value when the signal coil 3A generates the reference signal Vs1 at the reference crank angle position and when the count value of the timer provided in the microprocessor constituting the ignition control unit 3 is set. Sometimes executed. The microcomputer starts a timer counting operation when a signal generator (not shown) generates a reference signal, and then sets a new count value each time the count value of the timer matches the set count value, The set count value is counted.

  In the case of the algorithm shown in FIG. 3, first, in step S1, it is determined whether or not the current task execution timing is the reference signal generation timing. As a result, when it is determined that it is the generation timing of the reference signal, the process proceeds to step S2 and the “Va output timing detection count value”, which is a count value for detecting the timing for generating the boost operation stop command signal Va, is obtained. The timer is set to start the counting operation, and this task is completed.

  When the timer counts “Va output timing detection count value”, the task of FIG. 3 is executed again. At this time, since it is determined in step S1 that the current task execution timing is not the generation timing of the reference crank signal, step S3 is executed, and it is determined whether or not the current task execution timing is the Va output timing. This determination is performed by determining whether or not the count value of the timer matches the “Va output timing detection count value”. The “Va output timing detection count value” corresponds to the time from the timing at which the reference signal is generated to the timing at which the boost operation stop command signal Va is generated.

  If it is determined in step S3 that the current task execution timing is the Va output timing, the process proceeds to step S4 where the boost operation stop command signal Va is set to H level to stop the boost operation of the DC-DC converter. Next, in step S5, a count value ("Vip output timing detection count value") to be counted by the timer between the current timing and the timing at which the ignition position signal Vip is set to the L level (ignition position signal output timing). At the same time, the counting is started and this task is completed. The “Vip output timing detection count value” is set to 20 μsec, for example.

  When the timer counts “Vip output timing detection count value”, the task of FIG. 3 is executed again. At this task execution timing, it is determined in step S1 that the current task execution timing is not the generation timing of the reference signal, and in step S3, it is determined that the current task execution timing is not the Va output timing, so step S6 is executed. Is done. In step S6, it is determined whether or not the current task execution timing is the Vip output timing. This determination is made by checking whether the count value counted by the timer between the previous task execution timing and the current task execution timing matches the count value for detecting the Vip output timing.

  If it is determined in step S6 that the current task execution timing is the Vip output timing, the potential of the ignition position signal output port of the microcomputer is set to L level in step S7 to generate the ignition position signal Vip, and then in step S8. Then, a “Vip signal width setting count value” (for example, 10 μsec), which is a count value for setting the time during which the ignition position signal Vip is kept at the L level (Vip signal width), is set in the timer and this task is completed. .

  When the timer counts “Vip signal width setting count value”, the task of FIG. 3 is executed again. In this task execution timing, it is determined in step S1 that the current task execution timing is not the reference signal generation timing, in step S3 it is determined that the current task execution timing is not the Va output timing, and in step S6, the current task execution timing is determined. Since it is determined that the task execution timing is not the Vip output timing, the routine proceeds to step S9, where the ignition position signal Vip is set to H level and the boosting operation stop command signal Va is set to L level.

  Next, in step S10, a count value (“Va output timing detection count value”) for detecting the generation timing of the next boost operation stop command signal Va is calculated, and this task is completed. The “Va output timing detection count value” is a boost operation stop command from the “ignition position detection count value”, which is the time required for the crankshaft to rotate from the reference position to the ignition position signal Vip generation position (ignition position). The calculation is performed by subtracting the preceding time (20 μsec in this example) that determines the generation timing of the signal Va. The “count value for ignition position detection” is the time required for the crankshaft to rotate from the reference crank angle position to the ignition position calculated by the ignition control unit 3 at the current engine speed.

  In the example shown in FIG. 3, the timing for generating and extinguishing the boost operation stop command signal Va and the timing for generating and extinguishing the ignition position signal Vip (ignition signal Vi) using one timer provided in the microprocessor. However, the timing for generating and extinguishing the boost operation stop command signal and the timing for generating and extinguishing the ignition position signal are obtained using separate timers that operate in synchronization with each other. You can also

  In the above ignition device, if the differential capacitor C1 is charged when the power switch SW is closed, the differential circuit 2G does not generate the drive pulse Vd ', so that the boost circuit 2D does not perform the boost operation. If the step-up operation is not performed, no current flows through the secondary coil W2 of the step-up transformer, so that the transistor TR3 maintains a conductive state and the transistor TR4 maintains a cut-off state. When such a state occurs, the boosting operation cannot be started, and the ignition operation cannot be started. Further, when the power switch SW is turned on, the contact resistance of the switch is large, and even when the power supply voltage Vcc gradually rises, the differentiating circuit 2G does not generate the drive pulse Vd '. Arise.

  As in the above example, the boosting operation stop circuit 6 is provided, and the boosting operation stop command signal is given at the timing tp before the initialization time of the microprocessor constituting the ignition control unit 3 or the preceding time Tp before the ignition signal generation timing. By generating Va, the transistor TR9 is turned on to forcibly discharge the differential capacitor C1, and the differential operation of the differential circuit 2G is started when the boost operation stop command signal Va disappears. Since the drive pulse Vd 'can be reliably generated after the ignition signal is generated once when the engine is started, the possibility of the engine starting failing can be eliminated.

  In order to prevent the charge from remaining in the differential capacitor C1 when the engine is stopped, a reset switch that closes in conjunction with the switch when the power switch SW is opened is provided, and the reset switch is connected to one end of the differential capacitor C1. It is also possible to adopt a configuration in which the differential capacitor is discharged by connecting directly between the grounds or via a current limiting element.

  As described above, when the primary current of the step-up transformer 2B is detected and it is detected that the primary current has reached the set value, a voltage is induced in the secondary coil of the step-up transformer by cutting off the primary current. As a result, the primary current cutoff value can be made constant regardless of the battery voltage, and the voltage induced in the secondary coil of the step-up transformer can be made constant by the single cutoff of the chopper switch. It is possible to prevent the charging voltage of the ignition capacitor from being insufficient when the voltage drops.

  Further, as described above, when the secondary current of the step-up transformer 2B is detected and it is detected that the secondary current is less than a predetermined threshold value, the chopper switch circuit 2C is turned on so that the step-up transformer 2B is turned on. When the primary current is allowed to flow, the primary current does not flow when the secondary current is flowing through the step-up transformer, that is, when the magnetic flux is flowing through the iron core of the step-up transformer. It is possible to increase the efficiency of the booster circuit by preventing the power consumption in the transformer from increasing, and to prevent the heat generation of the booster transformer and the heat generation in the chopper switch circuit 2C from increasing. it can.

  Further, with the above configuration, since the primary current flows immediately after the secondary current becomes less than the threshold value, the load on the step-up transformer is reduced (the charging time of the ignition capacitor is advanced and the charging current flows for a short time). As a result, the on / off frequency of the chopper switch can be increased. Therefore, the charging speed of the ignition capacitor can be increased and the voltage induced in the secondary coil of the step-up transformer can be made constant regardless of the battery voltage. Satisfactory ignition operation can be performed by charging to a sufficiently high voltage.

  In the above example, the drive signal Vd is generated using the differentiating circuit 2G. However, in the present invention, the secondary current of the step-up transformer 2B (or the charging current of the capacitor Ci) is less than the threshold value. Sometimes a pulse having a certain time width may be generated as a drive signal, and the configuration of the circuit for generating the pulse is not limited to the above example.

  For example, when the secondary current of the step-up transformer 2B becomes less than a threshold value and the chopper drive command signal generation circuit 2E generates a chopper drive command signal, a drive pulse is generated by triggering a monostable multivibrator. You can also take

  In the above example, the chopper switch circuit 2C is configured with the FET as the main switch element (switch element for turning on and off the primary current of the step-up transformer), but other switch elements that can be turned on / off, such as transistors, are used as the main switch element. Of course, a chopper switch circuit can be configured as an element.

  In the above example, the ignition capacitor Ci of the ignition circuit 1 is connected in series with the primary coil of the ignition coil, but a known ignition circuit having a configuration in which the positions of the capacitor Ci and the thyristor Si are interchanged is used. The present invention can also be applied to such cases.

1 is a circuit diagram showing a hardware configuration of an ignition device for a capacitor discharge internal combustion engine according to an embodiment of the present invention. It is a wave form diagram for demonstrating operation | movement of embodiment of this invention. 6 is a flowchart showing an algorithm of a task executed by a microprocessor in order to control generation and extinction of a boost operation stop command signal and an ignition position signal in the embodiment of the present invention. It is a wave form diagram for demonstrating operation | movement of the conventional capacitor discharge type internal combustion engine ignition device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition circuit 2 Charging power supply part 2A Battery 2B Step-up transformer 2C Chopper switch circuit 2D Step-up circuit 2E Chopper drive command signal generation circuit 2F Differential control switch circuit 2G Differentiation circuit 2H Drive signal supply circuit 3 Ignition control unit 3B Microprocessor 4 Voltage detection circuit 5 Boost operation control circuit 6 Boost operation stop circuit

Claims (2)

A step-up transformer having a step-up transformer to which an output voltage of the battery is applied to a primary coil; a chopper switch circuit that conducts while the drive signal is applied and flows a primary current from the battery to the step-up transformer; When it is detected that the secondary current of the transformer is less than a predetermined threshold value, the chopper switch circuit is turned on to pass the primary current to the step-up transformer, and the primary current of the step-up transformer reaches a set value. The chopper switch circuit according to a primary current and a secondary current of the step-up transformer so as to induce a voltage in the secondary coil of the step-up transformer by turning off the chopper switch circuit when it is detected A DC-DC converter comprising a chopper switch control circuit for controlling
An ignition coil;
An ignition capacitor that is provided on a primary side of the ignition coil and is charged stepwise by a voltage intermittently output by the DC-DC converter;
An ignition control unit for generating an ignition signal at an ignition position of the internal combustion engine;
A discharge thyristor that turns on when the ignition signal is generated and discharges the charge accumulated in the ignition capacitor through a primary coil of the ignition coil;
A voltage detection circuit comprising a resistance voltage dividing circuit connected in parallel to the ignition capacitor;
The boost operation of the DC-DC converter is stopped when the charging voltage of the ignition capacitor detected by the voltage detection circuit exceeds a set level, and the charging voltage of the ignition capacitor becomes less than the set level. A step-up operation control circuit for controlling the step-up operation of the DC-DC converter according to the charging voltage of the charging capacitor so as to restart the step-up operation of the DC-DC converter sometimes.
A boosting operation stop command signal generating means for generating a boosting operation stop command signal for a set time in order to secure a time for turning off the discharging thyristor turned on in response to the ignition signal;
A step-up operation stop circuit for stopping the step-up operation of the DC-DC converter while the step-up operation stop command signal is generated;
In an ignition device for a capacitor discharge internal combustion engine equipped with
The boosting operation stop command signal generating means generates the boosting operation stop command signal at a timing preceding the timing at which the ignition signal is generated by a set preceding time, and is performed through the discharge thyristor. The boost operation stop command signal is extinguished at a timing immediately after the completion of the discharge of
An ignition device for a capacitor discharge internal combustion engine. The preceding time is a margin that is set at a time when a charging current flows from the DC-DC converter that resumes the boosting operation when the voltage across the ignition capacitor becomes less than the set level to the ignition capacitor. An ignition device for a capacitor discharge type internal combustion engine, wherein the ignition device is set equal to the time obtained by adding time.

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