JP5776372B2 - Ignition control device for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition control device for an internal combustion engine that controls energization and shut-off of a primary coil of an ignition coil mounted on the internal combustion engine.

  In general, an ignition device for an internal combustion engine has a configuration in which a secondary voltage is boosted and spark discharge is performed by interrupting energization of the primary coil with an IGBT (ignition switching element), but the energization of the primary coil is interrupted. As a result, electrical noise (blocking noise) is generated.

  This interruption noise can be reduced by slowing down the interruption speed I1 / dt of the primary current I1. Therefore, conventionally, a circuit (feedback circuit) is provided that allows a feedback current to flow from the collector of the IGBT to the gate when the collector potential of the IGBT becomes higher than the gate potential after the start of turning off the energization to the gate of the IGBT. (See Patent Document 1). According to this, since the gate potential is raised by the feedback current after the gate energization is turned off, the gate voltage decrease rate from when the gate energization is started until the gate voltage becomes zero becomes slow. For this reason, the shutoff speed I1 / dt can be slowed down, and thus the shutoff noise can be reduced.

Japanese Patent No. 3917865

  However, in the above-described conventional feedback circuit, a feedback current is allowed to flow even after the interruption noise is instantaneously generated. Therefore, it can be said that the period during which the interruption speed I1 / dt is delayed is excessively long. As a result, although the cut-off noise can be reliably reduced, the secondary voltage is lowered due to the low cut-off speed I1 / dt, which prevents the spark discharge from being stabilized. In addition, when the shutoff speed I1 / dt is reduced in this way, the time (ignition response time) required from when the IGBT is turned off to when spark discharge is performed becomes longer.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide an internal combustion engine ignition control device that achieves both a high secondary voltage, a short ignition response time, and a cut-off noise reduction. Is to provide.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

In the first invention, the ignition switching element for controlling energization and interruption to the primary coil constituting the ignition coil, and connected between the input terminal and the conduction control terminal of the ignition switching element, And a feedback switching element that controls whether or not to apply a voltage to the conduction control terminal for feedback.

  A parasitic capacitor existing between the feedback input terminal and the feedback conduction control terminal of the feedback switching element is charged by the cut-off noise voltage generated at the input terminal due to the off operation of the ignition switching element. The feedback switching element is configured to be turned on when the control voltage of the feedback conduction control terminal is increased, and when the parasitic capacitor is discharged, the control voltage is decreased and the feedback switching element is turned off. It is configured to operate.

  The above invention will be described below with reference to the example of FIG. 1 in which an IGBT (insulated gate bipolar transistor) is employed for the ignition switching element and the feedback switching element.

  In the above invention, when a feedback current flows from the input terminal (collector Cm) of the ignition switching element (main IGBT 31) to the conduction control terminal (gate Gm), the parasitic capacitor Cpara of the feedback switching element (sub-IGBT 32) is set as follows. It was used for.

  That is, a cutoff noise voltage induced by the primary coil is generated in the collector Cm as the main IGBT 31 is turned off, and the parasitic capacitor Cpara is charged by this cutoff noise voltage, and this charging causes the feedback conduction control terminal (gate Gs) to be charged. The sub-IGBT 32 is configured to be turned on when the control voltage increases.

  Therefore, the sub IGBT 32 is turned on with the main IGBT 31 being turned off, and a feedback current flows from the collector Cm of the main IGBT 31 to the gate Gm. As a result, the potential of the gate Gm is raised, the voltage drop rate of the gate Gm is decreased, and the primary current cutoff rate I1 / dt is also decreased. Therefore, the cut-off noise can be reduced.

  Further, in the above invention, the parasitic capacitor Cpara is charged and then the parasitic capacitor Cpara is discharged, whereby the control voltage of the gate Gs of the sub IGBT 32 is lowered, and the sub IGBT 32 is turned off.

  For this reason, when cut-off noise occurs, the sub-IGBT 32 is turned on by the charging of the parasitic capacitor Cpara and a feedback current flows. Then, the parasitic capacitor Cpara is immediately discharged, so that the sub-IGBT 32 is turned off and the feedback current does not flow. Therefore, since the feedback current flows only at the moment when the cut-off noise is generated, the period during which the cut-off speed I1 / dt of the primary current is delayed can be matched with the occurrence of the cut-off noise. Therefore, it is possible to increase the secondary voltage and shorten the ignition response time as compared with the conventional method in which the feedback current is supplied even after the generation of the interruption noise.

  As described above, according to the above-described invention, since the feedback current is caused to flow in accordance with the occurrence of the cut-off noise, it is possible to achieve both higher secondary voltage and shorter ignition response time and cut-off noise.

In the second invention, the parasitic capacitor is configured to be discharged from the feedback conduction control terminal side to the feedback output terminal of the feedback switching element, and between the feedback conduction control terminal and the feedback output terminal. And a discharge suppressing means for suppressing the discharge from the parasitic capacitor.

  Here, if the feedback conduction control terminal and the feedback output terminal are short-circuited without the discharge suppression means, even if a cutoff noise voltage is applied to the collector side of the sub IGBT 32, the charge on the gate side of the parasitic capacitor Cpara is stored. There is a risk of discharging the battery as it is. Then, the parasitic capacitor Cpara is not sufficiently charged, the control voltage at the gate Gs of the sub-IGBT 32 cannot be sufficiently increased, and it is difficult to reliably turn on the sub-IGBT 32. According to the above invention in view of this point, by providing the discharge suppression means (for example, the resistor R2 illustrated in FIG. 1), the parasitic capacitor Cpara is sufficiently charged, and the control voltage at the gate Gs of the sub-IGBT 32 is sufficient. As a result, the sub IGBT 32 can be reliably turned on.

  Incidentally, the discharge suppression means is not limited to the resistor R2. For example, a switching element may be employed as the discharge suppression means. In this case, the switching element (discharge suppression means) is used during the charging period of the parasitic capacitor Cpara. May be turned off and turned on during the discharge period.

In a third aspect of the invention, the ignition switching element and the feedback switching element are formed on the same chip. According to a fourth aspect of the present invention, the ignition switching element and the feedback switching element are disposed on the same heat sink.

Here, contrary to the first invention using a parasitic capacitor, an actual capacitor and a resistor are provided between the collector and gate of the main IGBT 31 so that the capacitor is charged with a cutoff noise voltage and a feedback current flows. Thus, the present inventors have found that the feedback current can be made to flow in accordance with the occurrence of the cut-off noise. However, when the capacitor is provided as described above, it is difficult to form the capacitor on the same chip as the main IGBT 31.

On the other hand, according to the first invention using the parasitic capacitor Cpara of the sub-IGBT 32, it is possible to easily form the sub-IGBT 32 on the same chip as the main IGBT 31, as in the third invention. The mounting space of the ignition control device for an internal combustion engine can be reduced. Further, as in the fourth aspect of the invention, it is possible to easily arrange the main IGBT 31 and the sub-IGBT 32 on the same heat sink, thereby reducing the mounting space for the internal combustion engine ignition control device.

According to a fifth aspect of the invention, there is provided limiting means for limiting a current from flowing from the conduction control terminal to the input terminal through the feedback switching element.

  Here, contrary to the above invention, if the limiting means is abolished, there is a concern that when the potential of the gate Gm of the main IGBT 31 becomes higher than the potential of the collector Cm, current flows backward from the gate Gm to the collector Cm through the sub IGBT 32. The In view of this point, the above-described invention includes a restriction unit (for example, the diode 33 illustrated in FIG. 5) that restricts the flow of current from the conduction control terminal to the input terminal through the feedback switching element. Can be eliminated.

  Incidentally, the limiting means is not limited to the diode 33. For example, a switching element may be employed as the limiting means. In this case, switching is performed when the potential of the gate Gm of the main IGBT 31 becomes higher than the potential of the collector Cm. The element (restricting means) is turned off, and it may be turned on at other times.

The circuit diagram which shows the ignition control apparatus concerning 1st Embodiment of this invention, and the ignition device which is the control object of the said control apparatus. The figure explaining the action | operation of the sub IGBT32 of FIG. The time chart which shows the various changes when it act | operates so that a feedback current may be sent only for the moment in generation | occurrence | production of interruption noise in 1st Embodiment. The enlarged view of FIG.3 (b) (c). The circuit diagram which shows the ignition control apparatus concerning 2nd Embodiment of this invention. The block diagram which shows the ignition control apparatus concerning 3rd Embodiment of this invention.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used. Further, in each embodiment described below, an ignition device for an internal combustion engine mounted on a vehicle is a control target.

(First embodiment)
FIG. 1 is a circuit diagram illustrating an ignition control device according to the present embodiment and an ignition device that is a control target of the control device. The ignition device includes an ignition coil 10 including a primary coil 11 and a secondary coil 12, and an ignition plug 13. Then, the primary coil 11 is energized from the direct current battery 20 mounted on the vehicle, and the energization is interrupted to generate an induced voltage (secondary voltage V2) in the secondary coil 12, and the secondary voltage V2 is generated. Is applied to the spark plug 13 to cause a spark discharge. The various electric devices 21 and the ignition device are connected in parallel so that electric power is supplied from the battery 20 to the various electric devices 21 mounted on the vehicle.

  Switching between energization and cutoff of the primary coil 11 is controlled by the main IGBT 31 (ignition switching element). The on / off operation of the main IGBT 31 is controlled by a gate signal output from the gate drive circuit 41 included in the monolithic integrated circuit (MIC chip 40). The gate drive circuit 41 is controlled by an ignition signal output from the electronic control unit (ECU 50).

  The ECU 50 calculates a target ignition timing according to the output rotation speed of the internal combustion engine, the load of the internal combustion engine, and the like, and sends an ignition signal to the gate drive circuit 41 so that the ignition coil 10 performs a spark discharge at the target ignition timing. Output.

  The ignition signal is a 5V pulse signal. At the rising timing of the ignition signal pulse, the gate drive circuit 41 outputs the gate signal, and the gate signal (gate voltage VGm) adjusted by the resistor R1 is the gate Gm of the main IGBT 31. Applied to (conduction control terminal). As a result, the main IGBT 31 is turned on so that the current I1 flows from the collector Cm (input terminal) to the emitter Em (output terminal) of the main IGBT 31, and the current (primary current I1) supplied from the battery 20 to the primary coil 11 is supplied. Flowing.

  On the other hand, at the falling timing of the ignition signal pulse, the gate drive circuit 41 stops outputting the gate signal, and the gate voltage VGm applied to the gate Gm is cut off. As a result, the main IGBT 31 is turned off, the primary current I1 is cut off, and the secondary voltage V2 is applied to the spark plug 13 to cause a spark discharge.

  The ignition control device includes a current limiting circuit 42 that limits the primary current I1 so as not to exceed a predetermined value. In the example shown in FIG. 1, the current limiting circuit 42 and the gate drive circuit 41 are the same. It is provided on a monolithic integrated circuit (MIC chip 40). The main IGBT 31 is provided on the same integrated circuit (IGBT chip 30) as the sub-IGBT 32 and the resistor R2 (discharge suppression means) described below. The IGBT chip 30 and the MIC chip 40 are housed in the same housing to form an igniter Ig. The igniter Ig and the ignition coil 10 are unitized as one assembly (ignition coil assembly As). ing.

  The igniter Ig includes a noise removing capacitor C. The capacitor C functions to remove noise propagating from the outside of the igniter Ig, and removes noise generated inside the igniter Ig. Function to suppress propagation to the outside.

  The sub IGBT 32 is connected between the collector Cm and the gate Gm of the main IGBT 31, and controls whether or not the voltage of the collector Cm (that is, the primary voltage V1 applied to the primary coil 11) is applied to the gate Gm and returned. .

  That is, when the applied voltage (gate voltage VGs) to the gate Gs (feedback conduction control terminal) of the sub IGBT 32 becomes equal to or higher than the threshold Vth, the current Iret from the collector Cs (feedback input terminal) of the sub IGBT 32 to the emitter Es (feedback output terminal). So that the sub-IGBT 32 is turned on. As a result, a feedback current Iret flows from the collector Cm of the main IGBT 31 to the gate Gm. On the other hand, when the gate voltage VGs of the sub IGBT 32 becomes less than the threshold value Vth, the sub IGBT 32 is turned off and the feedback current Iret is cut off.

  Here, when the gate signal to the main IGBT 31 is turned off and the primary current I1 to the primary coil 11 is cut off, a large voltage is generated as a cut-off noise in the collector Cm of the main IGBT 31 for the moment when the gate current is cut off. Then, the cutoff noise is LC-resonated by the parasitic coil Lpara existing on the electric path for supplying electric power from the battery 20 to the electric device 21 and the ignition coil 10 and the capacitor C, and the wire connected to the ignition coil assembly As. There is concern over propagation to various electrical devices 21 through the harness W or the like.

  Such cut-off noise can be reduced by slowing the cut-off speed of the primary coil 11 and slowing down the primary voltage (that is, the collector voltage VCm of the main IGBT 31). Therefore, the rate of decrease of the gate voltage VGm of the main IGBT 31 is slowed by flowing the feedback current Iret for a moment when the gate signal is turned off and the primary current I1 is cut off. As a result, the rate at which the collector voltage VCm (primary voltage V1) is cut off can be reduced, and the cut-off noise can be reduced.

  However, the longer the period during which the primary voltage V1 is decreased, the lower the secondary voltage V2, which hinders spark discharge stabilization at the spark plug 13. Further, the longer the period for slowing down the shutoff speed in this way, the longer the time (ignition response time) required to spark discharge with the spark plug 13 after the ignition signal is pulsed off and the gate signal is turned off, Spark discharge at the target ignition timing cannot be controlled with high accuracy.

  Therefore, if the sub-IGBT 32 is turned on for a moment when the primary current I1 is cut off to feed the feedback current Iret, the secondary voltage V2 can be increased, the ignition response time can be shortened, and the cut-off noise can be reduced. be able to. Therefore, in this embodiment, the parasitic capacitor Cpara and the resistor R2, which will be described below, apply the gate voltage VGs of the sub-IGBT 32 for an instant of interruption to realize the on operation.

  That is, as shown in FIGS. 1 and 2, the resistor R <b> 2 is connected between the gate Gs and the emitter Es of the sub IGBT 32. Although not shown in FIG. 1, a parasitic capacitor Cpara exists between the collector Cs and the gate Gs of the sub IGBT 32 as shown in FIG.

  Therefore, when the main IGBT 31 is turned off, the parasitic capacitor Cpara is charged by the cut-off noise voltage (the voltages of the collectors Cm and Cs) generated at that moment (see FIG. 2A). Incidentally, when the resistor R2 is eliminated and the gate Gs and the emitter Es are short-circuited, the charge on the gate Gs side of the parasitic capacitor Cpara only moves to the emitter Es as it is, and the gate voltage VGs of the sub IGBT 32 can be increased. Can not. Therefore, even if the voltage of the collectors Cm and Cs becomes high due to the cut-off noise voltage, the sub IGBT 32 is not turned on.

  On the other hand, when the cut-off noise voltage disappears and the voltages of the collectors Cm and Cs decrease, the parasitic capacitor Cpara is discharged (see FIG. 2B). Specifically, the electric charge charged in the parasitic capacitor Cpara gradually moves to the emitter Es while being limited by the resistor R2. That is, the gate voltage VGs gradually decreases.

  Therefore, as the resistance value of the resistor R2 is larger, the rate of decrease of the gate voltage VGs of the sub-IGBT 32 after the interruption noise is eliminated becomes slower. As a result, the rate of decrease of the gate voltage VGm of the main IGBT 31 is decreased. The shut-off speed of is slow. That is, it can be said that the rate of decrease of the gate voltage VGs can be adjusted by adjusting the resistance value of the resistor R2, and consequently the rate of decrease of the gate voltage VGm can be adjusted to adjust the cutoff rate of the primary coil 11. In short, the resistance R2 may be selected by determining the resistance value that optimizes the balance between increasing the secondary voltage V2 and shortening the ignition response time and reducing the cut-off noise by testing or the like.

  FIG. 3 is a time chart when the operation is performed so that the feedback current Iret is allowed to flow only for a moment when the cutoff noise is generated as described above. In the figure, (a) is an ignition signal output from the ECU 50, (b) is a gate voltage VGm of the main IGBT 31, (c) is a collector voltage VCm of the main IGBT 31, (d) is a primary current I1, and (e) is a wire. A current Iw flowing through the harness W, (f) indicates a voltage VB of a battery supply terminal provided in the igniter Ig, and (g) indicates a change in the secondary voltage V2.

  First, when the ignition signal pulse-on is output from the ECU 50 at time t1 (see (a)), the gate voltage VGm gradually increases (see (b)), and the gate voltage VGm becomes the battery voltage + B. At time t2 when the main IGBT 31 is reached, the main IGBT 31 is turned on, and the primary current I1 starts to flow from the collector Cm to the emitter Em. That is, at time t2, the collector voltage (primary voltage V1) drops to substantially the same potential as the ground voltage (see (c)), and the primary current I1 and current Iw start to rise (see (d) and (e)). .

  Thereafter, when the ignition signal pulse-on is output from the ECU 50 at time t3 (see (a)), the gate voltage VGm gradually decreases (see (b)). Then, at time t4 when the gate voltage VGm decreases to a predetermined threshold value, the main IGBT 31 starts to turn off, and a cutoff noise N is generated in the primary voltage V1 (see (c)).

  FIG. 4 is an enlarged view of FIGS. 3B and 3C, in which (h) indicates the gate voltage VGs of the sub-IGBT 32, and (i) indicates changes in the operating state of the sub-IGBT 32. Then, at time t4 when the cutoff noise N occurs, the parasitic capacitor Cpara is charged and the gate voltage VGs of the sub-IGBT 32 is raised (see (h)), and the sub-IGBT 32 starts to turn on (see (i)). . Thereafter, the gate voltage VGs decreases with the discharge from the parasitic capacitor Cpara, and at time t5 when the gate voltage VGs decreases to the predetermined threshold value Vth, the sub IGBT 32 is switched to the off operation.

  Therefore, the feedback current Iret flows into the gate Gm of the main IGBT 31 during the period from the time t4 when the cut-off noise N occurs to the time t5 when the parasitic capacitor Cpara is discharged to some extent, and the gate during the period t4 to t5 The rate of decrease in voltage VGm (the cutoff rate (I1 / dt) of primary current I1) is reduced.

  Incidentally, in the method of flowing the feedback current by the conventional method described in the above-mentioned Patent Document 1 and the like, as shown by the dotted line in FIG. 4, the sub-IGBT 32 is turned on until t6 after the interruption noise N disappears. It can be said that the period t4 to t6 in which the feedback current flows is excessively long.

  As described above, according to the present embodiment, the sub-IGBT 32 can be turned on with the voltage of the cut-off noise N by the parasitic capacitor Cpara and the resistor R2, so that the moment when the cut-off noise N is generated (period t4 to t5) ) The feedback current Iret.

  Therefore, compared to the device described in Patent Document 1 in which the feedback current Iret flows until no interruption noise N occurs, the interruption speed of the primary current I1 can be increased, so that the secondary voltage V2 is increased to spark discharge. Can be stabilized. Further, the response delay (ignition response time) required from the time point t3 when the ignition signal is pulsed off to the time point t7 when the secondary voltage V2 reaches the peak can be shortened, and the spark discharge at the target ignition timing can be controlled with high accuracy.

  Nevertheless, at the instants t4 to t5 when the cut-off noise N is generated, the feedback current Iret flows and the cut-off speed of the primary current I1 becomes slow, so that cut-off noise can be reduced. Specifically, the degree to which the current Iw of the wire harness W and the voltage VB of the battery supply terminal pulsate due to the LC resonance of the cutoff noise N can be reduced as shown in FIGS. As described above, it is possible to achieve both the increase in the secondary voltage V2 and the shortening of the ignition response time and the reduction of the cut-off noise.

  In addition, by adjusting the resistance value of the resistor R2, the end timing t5 of the period t4 to t5 in which the feedback current Iret flows can be easily adjusted, so that the feedback current Iret flows only at the moment when the cutoff noise N is generated. Can be easily realized.

(Second Embodiment)
In the present embodiment shown in FIG. 5, a diode 33 (limiter) is connected between the emitter Es of the sub IGBT 32 and the gate Gm of the main IGBT 31. The ignition control device according to this embodiment is the same as that of the first embodiment except for the provision of the diode 33.

  The diode 33 is connected in such a direction as to allow the feedback current Iret to flow from the collector Cm of the main IGBT 31 to the gate Gm and prevent the reverse current (see reference numeral Ia in FIG. 5) from flowing. . Specifically, the anode side of the diode 33 is connected to the emitter Es, and the cathode side is connected to the gate Gm.

  As described above, according to the present embodiment, even if the potential of the gate Gm of the main IGBT 31 is higher than the potential of the collector Cm, the diode 33 is provided, so that the gate Gm of the main IGBT 31 is transferred to the collector Cm. The current Ia can be prevented from flowing through the IGBT 32.

(Third embodiment)
In the present embodiment shown in FIG. 6A, the sub IGBT 32 is provided on the integrated circuit (IGBT chip 30) that constitutes the main IGBT 31. Therefore, the heat sink 31H attached to the main IGBT 31 is also used for heat dissipation of the sub-IGBT 32. Although not shown in FIG. 6, at least one of the resistor R 2 and the diode 33 is provided on the IGBT chip 30.

  Here, the present inventors examined mounting a capacitor instead of the parasitic capacitor Cpara. However, since it is difficult to provide the capacitor on the IGBT chip 30, a space for accommodating the capacitor is required in addition to the IGBT chip 30, so that the igniter Ig is increased in size.

  On the other hand, according to the present invention using the parasitic capacitor Cpara, the sub-IGBT 32 can be easily provided on the same chip 30 as the main IGBT 31 as in the present embodiment, so that the igniter Ig can be downsized. be able to. Furthermore, according to the present embodiment, since the heat sink 31H of the main IGBT 31 is also used for heat dissipation of the sub IGBT 32, it is possible to promote downsizing of the igniter Ig as compared with the case where a heat sink dedicated to the sub IGBT 32 is provided.

  FIG. 6B is a diagram showing a modification of FIG. 6A, in which an IC chip 30A constituting the main IGBT 31 and an IC chip 30B constituting the sub IGBT 32 are provided separately. In this case, it is desirable to provide the resistor R2 on the same IC chip 30B as that of the sub IGBT 32.

  Even when separate IC chips 30A and 30B are provided in this way, as shown in FIG. 6B, both IC chips 30A and 30B are radiated by a common heat sink 31H, and an igniter Ig is obtained. It is desirable to reduce the size.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows. Moreover, you may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  In each of the above embodiments, an insulated gate bipolar transistor (IGBT) is employed as the ignition switching element and the feedback switching element, and at least one of these switching elements is a metal oxide semiconductor field effect transistor (MOSFET). May be adopted.

  In each of the above embodiments, the resistor R2 is employed as the discharge suppression unit. However, for example, a switching element may be employed as the discharge suppression unit. In this case, when the cutoff noise N is generated, the switching element (discharge suppression means) is turned off to charge the parasitic capacitor Cpara. After the generation of the cutoff noise N or during the generation period, the switching element is turned on to turn on the parasitic capacitor Cpara. It is sufficient to start the discharge.

  In each of the above embodiments, the diode 33 is used as the limiting unit. However, for example, a switching element may be used as the limiting unit. In this case, when the potential of the gate Gm of the main IGBT 31 becomes higher than the potential of the collector Cm, the switching element (restricting means) is turned off to prevent the reverse flow indicated by reference numeral Ia in FIG. It only has to be turned on.

  DESCRIPTION OF SYMBOLS 11 ... Primary coil, 30 ... IGBT chip, 31 ... Main IGBT (switching element for ignition), 31H ... Heat sink, 32 ... Sub IGBT (switching element for feedback), 33 ... Diode (limitation means), Cm ... Collector (for ignition) Switching element input terminal), Gm ... gate (conduction control terminal of ignition switching element), Cs ... collector (feedback input terminal of feedback switching element), Gs ... gate (feedback control terminal of feedback switching element), Cpara: parasitic capacitor, Iret: feedback current, R2: resistance (discharge suppression means), VGs: gate voltage (control voltage).

Claims (4)

An ignition switching element for controlling energization and shutoff of the primary coil constituting the ignition coil;
A feedback switching element that is connected between an input terminal of the ignition switching element and a conduction control terminal, and that controls whether to apply a voltage of the input terminal to the conduction control terminal for feedback; and
With
A parasitic capacitor that exists between a feedback input terminal and a feedback conduction control terminal of the feedback switching element due to a cut-off noise voltage generated at the input terminal as a result of the ignition switching element being turned off. A parasitic capacitor having a parasitic capacitance is charged, and by this charging, the control voltage of the feedback conduction control terminal rises, and the feedback switching element is configured to be turned on,
And, when the parasitic capacitor is discharged, the control voltage is lowered and the feedback switching element is configured to be turned off .
The parasitic capacitor is configured to be discharged from the feedback conduction control terminal side to the feedback output terminal of the feedback switching element,
An ignition control device for an internal combustion engine, comprising: a discharge suppression unit that is connected between the feedback conduction control terminal and the feedback output terminal and suppresses the discharge from the parasitic capacitor. The ignition control device for an internal combustion engine according to claim 1, wherein the ignition switching element and the feedback switching element are formed on the same chip. The ignition control device for an internal combustion engine according to claim 1 or 2, wherein the ignition switching element and the feedback switching element are disposed on the same heat sink. The internal combustion engine ignition according to any one of claims 1 to 3 , further comprising limiting means for restricting a current from flowing from the conduction control terminal to the input terminal through the feedback switching element. Control device.

Images