JP2014037778A - Ignition device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition device of an internal combustion engine capable of keeping a discharge voltage generated on a secondary winding substantially constant for a prescribed time without using a high withstand voltage element.SOLUTION: In an ignition device of an internal combustion engine including an ignition coil 10 generating high voltage on a secondary winding by increasing or decreasing electric current of a primary winding, a DC power source connected to the primary winding, an ignition plug 12 igniting a fuel by receiving high voltage generated in the secondary winding, and an IGBT 11 functioning as a switch for interrupting and conducting electric current of the primary winding, a capacitor 22 of a prescribed capacity is connected between a gate terminal and a collector terminal of the IGBT 11, and electric charge corresponding to the prescribed capacity, is supplied to the gate terminal from the capacitor 22 when the IGBT 11 is switched off to keep high voltage generated in the secondary winding at a specific value for a prescribed time in switching the IGBT 11 off.

Description

  The present invention relates to ignition of an internal combustion engine in which a high voltage is generated in a secondary winding by increasing / decreasing a current in a primary winding of an ignition coil, and a spark is generated in a spark plug by the generated high voltage to ignite fuel. Relates to the device.

  In Patent Document 1, in order to suppress variations in the discharge voltage, a voltage waveform generated in the secondary winding is obtained by inserting a constant voltage element in parallel with the spark plug on the secondary winding side of the ignition coil. It has a flat peak waveform.

Japanese Patent Publication No. 6-80313

  By the way, in recent years, there is a tendency to increase the applied voltage and perform ignition in a short time.

  Here, in the spark plug, the higher the voltage applied between the electrodes, the more easily the discharge phenomenon occurs when the voltage is applied for a short time. That is, if the voltage applied to the spark plug is lowered, it is necessary to continue to apply a constant voltage to the spark plug for a longer time. However, generally, the waveform of the voltage generated in the secondary winding has a sharp peak waveform, and the voltage generated in the secondary winding cannot be maintained for a predetermined time.

  In this regard, in the device described in Patent Document 1, although the variation of the discharge voltage can be suppressed by the constant voltage element, the voltage generated in the secondary winding may not be maintained for a predetermined time.

  Furthermore, since the ignition device of Patent Document 1 uses a high-voltage constant voltage element on the secondary winding side of the ignition coil, there are problems such as an increase in cost, an increase in physique, and a decrease in reliability.

  In view of the above circumstances, an object of the present invention is to provide an ignition device for an internal combustion engine that can make a discharge voltage generated in a secondary winding substantially constant for a predetermined time without using a high-voltage element. .

  In order to solve the above-described problem, an invention according to claim 1 is an ignition device for an internal combustion engine, wherein an ignition coil that generates a high voltage in a secondary winding by increasing or decreasing a current in a primary winding, and the primary coil MOS gate structure transistor that functions as a DC power source connected to the winding, a spark plug that ignites the fuel upon receiving a high voltage generated in the secondary winding, and a switch that interrupts the current in the primary winding An ignition device for an internal combustion engine comprising: a capacitor having a predetermined capacity connected between a gate terminal and a collector terminal of the transistor, which is generated in the secondary winding when the transistor is turned off. In order to maintain the high voltage at a constant value for a predetermined time, a charge corresponding to the predetermined capacity is supplied from the capacitor to the gate terminal when the transistor is turned off.

  According to the first aspect of the present invention, when the MOS gate structure transistor is turned on, a current flows through the primary winding to accumulate electromagnetic energy. Thereafter, when the MOS gate structure transistor is turned off, electromagnetic energy stored in the primary winding is transmitted, and an induced voltage corresponding to a change in the current of the primary winding is generated in the secondary winding. At this time, when the current flowing through the primary winding decreases rapidly, the waveform of the voltage generated in the secondary winding becomes a waveform having a sharp peak. In order to make the waveform of the voltage generated in the secondary winding into a flat peak waveform, it is necessary to moderate the current change in the primary winding.

  According to the first aspect of the present invention, a capacitor is connected between the gate terminal and the collector terminal of the MOS gate structure transistor. Therefore, when the MOS gate structure transistor is turned on, a voltage is applied to the capacitor and electric charges are accumulated. When the MOS gate structure transistor is turned off, the electric charge accumulated in the capacitor is supplied to the gate terminal, and the gate voltage is boosted to the vicinity of the threshold voltage. The threshold voltage is a gate voltage serving as a boundary between ON and OFF of the MOS gate structure transistor. When the gate voltage is kept near the threshold voltage, the MOS gate structure transistor is in a half-on state, and current starts to leak from the collector terminal to the emitter terminal.

  The leakage current gradually increases as the charge accumulates in the MOS gate structure transistor, and then stops flowing as the charge accumulated in the capacitor decreases. On the other hand, when the MOS gate structure transistor is turned off, the current flowing through the primary winding gradually decreases and then temporarily stops flowing in response to the change in the leakage current. Therefore, the current of the primary winding can be appropriately changed by appropriately setting the predetermined capacity and adjusting the time for flowing the leak current. As a result, the high voltage generated in the secondary winding can be maintained at a substantially constant value for a predetermined time. Therefore, since a certain level of high voltage generated in the secondary winding is applied to the spark plug for a predetermined time, the spark plug discharge phenomenon is suppressed while preventing the high voltage generated in the secondary winding from becoming excessively high. Can occur.

The circuit diagram of the ignition device of the internal-combustion engine concerning a 1st embodiment. The figure which shows the discharge voltage waveform by the ignition device of the internal combustion engine which concerns on 1st Embodiment. The figure which shows the discharge voltage waveform by the ignition device of the conventional internal combustion engine. The circuit diagram of the ignition device of the internal combustion engine which concerns on 2nd Embodiment. The figure which shows the discharge voltage waveform in case a primary interruption | blocking current is 8A. The figure which shows the discharge voltage waveform in case a primary interruption | blocking current is 9.5A. The figure which shows the discharge voltage waveform in case a primary interruption | blocking current is 11A. The circuit diagram of the ignition device of the internal combustion engine which concerns on other embodiment. The circuit diagram of the ignition device of the internal combustion engine which concerns on other embodiment. The circuit diagram of the ignition device of the internal combustion engine which concerns on other embodiment. The circuit diagram of the ignition device of the internal combustion engine which concerns on other embodiment. The circuit diagram of the ignition device of the internal combustion engine which concerns on other embodiment. The circuit diagram of the ignition device of the internal combustion engine which concerns on other embodiment.

  Hereinafter, embodiments embodying an ignition device for an internal combustion engine will be described with reference to the drawings. The ignition device for an internal combustion engine according to each embodiment is assumed to be mounted on a vehicle using the internal combustion engine as a power source. 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.

(First embodiment)
First, the configuration of the circuit of the ignition device for an internal combustion engine according to the first embodiment will be described with reference to FIG. The ignition device includes an ignition coil 10, an ignition plug 12 connected to the secondary winding side of the ignition coil 10, a battery 14 (DC power supply) connected to the primary winding side of the ignition coil 10, and a primary winding. It includes an IGBT 11 (MOS gate structure transistor) which is a switch for interrupting the line current.

  The IGBT 11 has a collector terminal connected to the primary winding of the ignition coil 10, an emitter terminal connected to the ground potential, and a base terminal connected to the input resistor 17. Further, a series body in which a resistor 23 having a predetermined size, a capacitor 22 having a predetermined capacity, and a Zener diode 21 having a predetermined breakdown voltage are connected in series between the gate terminal and the collector terminal of the IGBT 11 in this order from the gate terminal side. 20 is connected. Further, a Zener diode 13 that protects the IGBT 11 from overvoltage is connected in parallel with the series body 20 between the gate terminal and the collector terminal of the IGBT 11. The Zener diode 21 and the Zener diode 13 are connected in the direction from the gate terminal to the collector terminal, that is, reversely connected in the direction from the collector terminal to the gate terminal. The withstand voltage of the Zener diode 21 is set lower than the withstand voltage of the Zener diode 13, and the withstand voltage of the Zener diode 13 is set lower than the withstand voltage between the collector terminal and the emitter terminal of the IGBT 11. Further, a relatively large resistor (not shown) for current limitation is connected between the Zener diode 21 and the collector terminal. Also, a relatively large resistor (not shown) for current limitation is connected between the Zener diode 13 and the collector terminal.

  Next, the operation of the ignition device will be described. When the ignition signal IGT is input to the gate terminal of the IGBT 11 via the input resistor 17, a voltage is applied to the gate terminal, an inversion layer is formed in the MOSFET part of the IGBT 11, and the MOSFET part is turned on. Then, the drain current of the MOSFET part flows as the base current of the pnp transistor part of the IGBT 11, and the IGBT 11 is turned on. At this time, the voltage applied to the gate terminal is sufficiently higher than the threshold voltage of the IGBT 11, and this state is referred to as full-on. The threshold voltage is a voltage when the inversion layer is formed in the IGBT 11 and is a voltage that becomes a boundary between the on and off of the IGBT 11. When the IGBT 11 is turned on, a constant current flows through the primary winding of the ignition coil 10, and electromagnetic energy is accumulated in the primary winding.

  Next, when the ignition signal IGT is turned off, the turn-off transition of the IGBT 11 starts. When the turn-off transition of the IGBT 11 starts, the primary current flowing through the primary winding decreases, and an induced voltage corresponding to a change in the primary winding current is generated in the primary winding by self-induction. At the same time, a high voltage corresponding to a change in the primary current is induced in the secondary winding by mutual induction. Therefore, when the primary current flowing through the primary winding is rapidly reduced when the IGBT 11 is turned off, the waveform of the secondary voltage generated in the secondary winding becomes a waveform having a sharp peak.

  In this ignition device, since the series body 20 of the resistor 23, the capacitor 22 and the Zener diode 21 is connected between the gate terminal and the collector terminal of the IGBT 11, the primary current is gently reduced when the IGBT 11 is turned off. Change. Therefore, the waveform of the secondary voltage is a flat peak waveform. That is, the secondary voltage can be maintained at a substantially constant value for a predetermined time. Hereinafter, the operation of the serial body 20 will be described in detail.

  When the ignition signal IGT is input and input to the gate terminal of the IGBT 11, a voltage is applied to the capacitor 22, and charges corresponding to a predetermined capacity are accumulated in the capacitor 22. When the ignition signal IGT is turned off and the IGBT 11 is turned off, the primary current decreases and a primary voltage is induced in the primary winding. While the primary voltage is smaller than the withstand voltage of the Zener diode 21, the charge is not transferred from the capacitor 22 because it is equal to the state where the capacitor 22 and the collector terminal are open. When the potential of the primary voltage rises and becomes higher than the predetermined breakdown voltage of the Zener diode 21, the capacitor 22 and the collector terminal are brought into conduction. Then, the electric charge accumulated in the capacitor 22 moves, and a minute current flows from the capacitor 22 through the resistor 23 to the gate terminal. That is, when the IGBT 11 is turned off, a charge corresponding to the predetermined capacity is supplied from the capacitor 22 to the gate terminal so that the high voltage generated in the secondary winding when the IGBT 11 is turned off is maintained at a constant value for a predetermined time. .

  At this time, as the predetermined capacity of the capacitor 22 is larger and the accumulated charge is larger, the current flowing from the capacitor 22 to the gate terminal flows for a longer time while gradually decreasing. Further, as the predetermined size of the resistor 23 is smaller, a larger current flows from the capacitor 22 to the gate terminal for a shorter time. Therefore, by appropriately setting the capacitance of the capacitor 22 and the size of the resistor 23, the magnitude of the minute current flowing from the capacitor 22 to the gate terminal and the flowing time can be adjusted.

  When the adjusted minute current flows into the gate terminal, the gate voltage is raised near the threshold voltage. As a result, an inversion layer is formed in the MOSFET portion of the IGBT 11, but the inversion layer is not completely formed because the gate voltage is not sufficiently higher than the threshold value, and a slight current starts to leak from the collector terminal to the emitter terminal. . Thus, unlike the full-on state (MOSFET saturation region state), the state in which a leakage current flows from the collector terminal to the emitter terminal is called half-on (MOSFET non-saturation region state).

  The leakage current gradually increases as charges accumulate in the IGBT 11, and then decreases and does not flow as the charge accumulated in the capacitor 22 decreases. When the electric charge accumulated in the capacitor 22 is completely eliminated, the IGBT 11 is turned off.

  By the way, the primary current after the turn-off transition of the IGBT 11 starts changes in accordance with the change of the leakage current. Therefore, by appropriately changing the leakage current, the primary current can be appropriately changed so that the secondary voltage becomes a substantially constant value for a predetermined time.

  The time when the leak current starts to leak, the magnitude of the leak current, and the time during which the leak current flows depend on the time when the current starts to flow from the capacitor 22 to the gate terminal, the magnitude of the current flowing into the gate terminal, and the flow time. Determined. That is, the leak current changes according to the predetermined breakdown voltage of the Zener diode 21, the predetermined magnitude of the resistor 23, and the predetermined capacity of the capacitor 22.

  Accordingly, by appropriately setting the predetermined breakdown voltage of the Zener diode 21, the predetermined size of the resistor 23, and the predetermined capacity of the capacitor 22, the leakage start time of the leakage current, the size of the leakage current, and the time for flowing the leakage current are reduced. It is adjusted and the primary current changes appropriately.

  Next, FIG. 2 shows changes in the gate voltage, primary current, primary voltage, and secondary voltage when the IGBT 11 is turned off in the ignition device. FIG. 3 shows changes in the gate voltage, primary current, primary voltage, and secondary voltage when the IGBT 11 is turned off in a general ignition device that does not include the series body 20 of the ignition device.

  In a general ignition device, as shown in FIG. 3, when the turn-off transition of the IGBT 11 starts, the primary current decreases rapidly. With the rapid change of the primary current, the primary voltage also rapidly increases and reaches the withstand voltage of the Zener diode 13 at the time point G. When the primary voltage reaches the withstand voltage of the Zener diode 13, the collector voltage is clamped to approximately the withstand voltage of the Zener diode 13, and the IGBT 11 is protected from overvoltage.

  Furthermore, a current flows from the collector terminal to the gate terminal, the gate voltage rises and becomes half-on, and a leak current starts to flow from the collector terminal to the emitter terminal. Since a relatively large resistor for current limiting is connected to the Zener diode 13, when the IGBT 11 is half-on, current flows from the collector terminal to the emitter terminal of the IGBT 11, and current does not easily flow through the Zener diode 13. As a result, at time H, the gate voltage becomes 0, the IGBT 11 is turned off, and the primary voltage starts to drop.

  On the other hand, the secondary voltage induced in response to the change in the primary current rapidly decreases until reaching a very high voltage until time point G, and further decreases without being maintained at a constant value.

  Even in a general ignition device, when the primary voltage rises to the withstand voltage of the Zener diode 13, a leakage current flows from the collector terminal to the emitter terminal. However, since the withstand voltage of the Zener diode 13 for overvoltage protection is set high, the secondary voltage has already increased to a voltage value exceeding the withstand voltage of the spark plug 12 before the leak current starts to leak. . Particularly in recent years, such a situation is likely to occur because the applied voltage tends to be increased to perform ignition in a short time. Further, the zener diode 13 alone cannot adjust the magnitude and time of the current flowing into the gate terminal, so that the leakage current cannot be changed appropriately. As a result, the secondary voltage cannot be maintained at a substantially constant value for a predetermined time by appropriately changing the primary current.

  On the other hand, in this ignition device, as shown in FIG. 2, the primary current, the gate voltage, the primary voltage, and the secondary voltage change until time A, as in a general ignition device. However, when the primary voltage rises to the withstand voltage of the Zener diode 21 at time A, the gate voltage rises, the IGBT 11 is half-on, and a leak current starts to flow. Therefore, after the time point A, the primary current gradually decreases as compared with a general ignition device, and then increases with an increase in charge moving from the capacitor 22 to the gate terminal. In addition, with the gradual change of the primary current, the primary voltage also gradually increases as compared with a general ignition device. At time B, the leakage current begins to decrease due to the decrease in the charge accumulated in the capacitor 22, and thus the primary current begins to decrease. Thereafter, at time C, the primary voltage reaches the withstand voltage of the Zener diode 13. Since the temporary voltage rises more slowly than a general ignition device, the time point C is later than the time point G.

  Even when the primary voltage reaches the withstand voltage of the Zener diode 13, since the current has already flowed from the collector terminal to the emitter terminal of the IGBT 11, almost the current flows through the Zener diode 13 to which a relatively large resistor for current limitation is connected. Absent. At time D, the charge accumulated in the capacitor 22 disappears, the IGBT 11 is turned off, and the primary voltage starts to drop.

  On the other hand, the secondary voltage induced according to the change in the primary current is maintained at a substantially constant value for a predetermined time because the primary current gradually increases and decreases between the time A and the time D. Further, since a leak current starts to flow at an earlier time than a general ignition device, the peak value of the secondary voltage is lower than that of a general ignition device.

  Here, it is better to design the predetermined breakdown voltage of the Zener diode 21 higher as the target value of the secondary voltage applied to the spark plug 12 is higher. In this way, when the target secondary voltage is high, the secondary voltage is sufficiently boosted before the primary voltage reaches the withstand voltage of the Zener diode 21, and thus a high secondary voltage is likely to be generated.

  According to 1st Embodiment described above, there exist the following effects.

  -By appropriately setting the predetermined capacity of the capacitor 22 and the predetermined size of the resistor 23, the time for flowing the leak current and the magnitude of the leak current are adjusted, and the predetermined breakdown voltage of the Zener diode 21 is set appropriately. Thus, the leak start time of the leak current can be adjusted. Therefore, the current of the primary winding can be appropriately changed. As a result, the high voltage generated in the secondary winding of the ignition coil 10 can be maintained at a substantially constant value for a predetermined time. Therefore, since the high voltage generated in the secondary winding of the ignition coil 10 is applied to the spark plug 12 for a predetermined time, the spark plug 12 is prevented from excessively increasing the high voltage generated in the secondary winding. The discharge phenomenon can be caused.

  -Since this ignition device connects the serial body 20 to the primary side of the ignition coil 10, it can set the withstand voltage of the serial body 20 low compared with the case where the serial body 20 is connected to the secondary side. Therefore, the ignition device for the internal combustion engine can be downsized as compared with the case where a high voltage element is connected to the secondary side.

(Second Embodiment)
With reference to FIG. 4, the structure of the circuit of the ignition device of the internal combustion engine which concerns on 2nd Embodiment is demonstrated. In the ignition device for an internal combustion engine according to the second embodiment, serial bodies 30, 40, and 50 are connected in parallel between the gate terminal and the collector terminal of the IGBT 11 in order from the gate terminal side. The series bodies 30, 40, 50 are respectively provided with resistors 33, 43, 53 having a predetermined size, capacitors 32, 42, 52 having a predetermined capacity, Zener diodes 31, 41, 51 having a predetermined breakdown voltage, and bipolar transistors 34, 44, 54 (changeover switch) is connected in series.

  A primary current detection resistor 15 is connected in parallel between the emitter terminal of the IGBT 11 and the ground potential. Further, a current detection circuit 16 that detects a current flowing through the resistor 15 and transmits an ON signal to each of the transistors 34, 44, and 54 is connected.

  In this ignition device, a transistor that is switched to energization (turned on) is selected from the transistors 34, 44, and 54 in accordance with the magnitude of the primary current (primary cutoff current) at the start of the turn-off transition of the IGBT 11. That is, the series body to be conducted is selected according to the magnitude of the primary cutoff current.

  The predetermined capacities of the capacitors 32, 42, and 52 are different from each other. In this ignition device, the predetermined capacity of the capacitor 32 is set to be the largest, and the predetermined capacity of the capacitor 52 is set to be the smallest. The predetermined sizes of the resistors 33, 43, and 53 are also different. In the present ignition device, the predetermined size of the resistor 33 is set to the smallest, and the predetermined size of the resistor 53 is set to the largest. That is, the predetermined magnitude is set smaller as the resistance is connected to a capacitor having a larger predetermined capacity.

  By combining the resistor 33 having a small predetermined size and the capacitor 32 having a large predetermined capacitance, a large leak current can be adjusted to flow for a long time. Further, by combining the resistor 53 having a large predetermined size and the capacitor 52 having a small predetermined capacitance, it is possible to adjust so that a small leak current flows for a short time. That is, it is possible to adjust so that when the transistor 34 is turned on, the amount of leak current that flows is the largest, and when the transistor 54 is turned on, the amount of leak current that flows is the smallest.

  Further, the predetermined withstand voltages of the Zener diodes 31, 41, 51 are set according to the withstand voltage of the spark plug 12, that is, the target secondary voltage, and therefore all have the same value.

  The primary cutoff current often has a different value each time the IGBT 11 is turned off. The larger the primary cutoff current, the more the primary current tends to decrease when turning off the IGBT. That is, the larger the primary cutoff current, the greater the negative slope of the primary current. Therefore, when the primary cutoff current is larger, the amount of leakage current is increased and the change in the primary current is moderated, whereby the secondary voltage is easily maintained at a substantially constant value for a predetermined time.

  Taking the case where the transistor 44 is turned on as an example, when the IGBT 11 is turned off, changes in gate voltage, primary current, primary voltage and secondary voltage when the primary cutoff current is 8A, 9.5A, 11A are shown. These are shown in FIGS.

  As shown in FIG. 6, when the primary breaking current is 9.5 A, the secondary voltage is maintained at a substantially constant value for a predetermined time. Therefore, in this case, it can be said that the predetermined capacity of the capacitor 42 and the predetermined size of the resistor 43 are set appropriately. On the other hand, as shown in FIGS. 5 and 7, when the primary cutoff current is 8A and 11A, the secondary voltage is not maintained at a substantially constant value for a predetermined time.

  When the primary cut-off current is 8 A, the negative slope of the primary current becomes too small, so that the secondary voltage reaches its peak late. In this case, since the predetermined capacity of the capacitor 42 and the predetermined size of the resistor 43 are not set appropriately, it is considered that the leakage current is increased and the negative gradient of the primary current is too small. Therefore, when the primary cutoff current is 8 A, it is appropriate to turn on the transistor 54 of the series body 50.

  In addition, when the primary cutoff current is 11 A, since the time during which the leakage current flows is too short, after the secondary voltage reaches the peak, the drop starts without being maintained at the peak value. Also in this case, since the predetermined capacity of the capacitor 42 and the predetermined size of the resistor 43 are not appropriately set, it is considered that the time during which the leakage current flows is shortened and the secondary voltage is not maintained for the predetermined time. Therefore, when the primary cutoff current is 11 A, it is appropriate to turn on the transistor 34 of the series body 30.

  In this ignition device, the primary cutoff current is detected by the current detection circuit 16 and the transistor 34 of the series body 30 to which the capacitor 32 having a larger predetermined capacity is connected is turned on as the detected primary cutoff current is larger. That is, the secondary voltage is easily maintained at a substantially constant value for a predetermined time by adjusting so that the larger the primary cutoff current is, the larger the leak current flows for a longer time. On the contrary, as the detected primary cutoff current is smaller, the transistor 54 of the series body 50 connected to the capacitor 52 having a smaller predetermined capacity is turned on.

  According to 2nd Embodiment described above, there exist the following effects.

  -The larger the magnitude of the primary cutoff current, the larger the leak current can be adjusted to flow for a longer time, and the leak start timing of the leak current can be adjusted by appropriately setting the predetermined withstand voltage. Therefore, the current of the primary winding can be changed more appropriately when turning off the IGBT 11 regardless of the magnitude of the primary cutoff current. As a result, the high voltage generated in the secondary winding is easily maintained at a substantially constant value for a predetermined time regardless of the magnitude of the primary current.

(Other embodiments)
In the first embodiment, as shown in FIG. 8, the series body 20 connected between the gate terminal and the collector terminal of the IGBT 11 may be only the capacitor 22. If the predetermined capacity of the capacitor 22 is set appropriately, the time during which the leakage current flows can be adjusted, so that the primary current can be changed appropriately.

  In the first embodiment, as shown in FIG. 9, the series body 20 connected between the gate terminal and the collector terminal of the IGBT 11 may be a series body in which a resistor 23 and a capacitor 22 are connected in series. If the predetermined capacity of the capacitor 22 and the predetermined size of the resistor 23 are appropriately set, the magnitude of the leakage current and the time during which the leakage current flows can be adjusted, so that the primary current can be appropriately changed.

  In the first embodiment, as shown in FIG. 10, the series body 20 connected between the gate terminal and the collector terminal of the IGBT 11 may be a series body in which a capacitor 22 and a Zener diode 21 are connected in series. If the predetermined capacity of the capacitor 22 and the predetermined breakdown voltage of the Zener diode 21 are set appropriately, the time when the leak current starts to leak and the time during which the leak current flows can be adjusted, so that the primary current can be changed appropriately.

  In the second embodiment, as shown in FIG. 11, the series bodies 30, 40, 50 connected between the gate terminal and the collector terminal of the IGBT 11 are capacitors 32, 42, 52 and bipolar transistors 34, 44, 54 may be connected in series. In this way, the larger the primary cutoff current is, the more the series body connected with a capacitor having a large predetermined capacity is energized, and the leakage current can be adjusted to flow longer. Therefore, the primary current can be appropriately changed according to the magnitude of the primary cutoff current.

  In the second embodiment, as shown in FIG. 12, the series bodies 30, 40, 50 connected between the gate terminal and the collector terminal of the IGBT 11 include resistors 33, 43, 53 and capacitors 32, 42, 52, respectively. And transistors 34, 44, 54 may be connected in series. In this way, the larger the primary cutoff current, the more the series body connected with the capacitor having a large predetermined capacity and the resistor having a small predetermined magnitude is energized, and a large leak current can be adjusted to flow long. Therefore, the primary breaking current can be appropriately changed according to the magnitude of the primary current.

  In the second embodiment, as shown in FIG. 13, the series bodies 30, 40, 50 connected between the gate terminal and the collector terminal of the IGBT 11 include capacitors 32, 42, 52 and Zener diodes 31, 41, A serial body in which 51 and transistors 34, 44, and 54 are connected in series may be used. In this way, the larger the primary cutoff current is, the more the series body connected with a capacitor having a large predetermined capacity is energized, and the leakage current can be adjusted to flow longer, and the leakage start timing of the leakage current can be adjusted. Therefore, the primary current can be appropriately changed according to the magnitude of the primary cutoff current.

  In the second embodiment, the negative slope of the primary breaking current may be detected, and the magnitude of the negative slope may be used instead of the magnitude of the primary breaking current. Further, both the magnitude of the primary cutoff current and the magnitude of the negative gradient may be used.

  In the second embodiment, three series bodies are connected between the gate terminal and the collector terminal of the IGBT 11, but the number of series bodies may be set as appropriate. If the number of series bodies increases, the primary current can be appropriately changed correspondingly to the change in the magnitude of the primary cutoff current.

  -In 2nd Embodiment, you may employ | adopt MOSFET, a relay switch, etc. instead of the bipolar transistors 34,44,54.

  DESCRIPTION OF SYMBOLS 10 ... Ignition coil, 11 ... IGBT, 12 ... Spark plug, 13, 21, 31, 41, 51 ... Zener diode, 14 ... Battery, 22, 32, 42, 52 ... Capacitor, 23, 33, 43, 53 ... Resistance .

Claims (7)

Ignition coil (10) for generating a high voltage in the secondary winding by increasing or decreasing the current in the primary winding, a DC power supply (14) connected to the primary winding, and a high voltage generated in the secondary winding An ignition device for an internal combustion engine, comprising: an ignition plug (12) for igniting fuel by being supplied with a MOS gate structure transistor (11) functioning as a switch for interrupting the current of the primary winding;
A capacitor (22) having a predetermined capacity is connected between the gate terminal and the collector terminal of the transistor so as to maintain a high voltage generated in the secondary winding at a constant value for a predetermined time when the transistor is turned off. An ignition device for an internal combustion engine, wherein when the transistor is turned off, a charge corresponding to the predetermined capacity is supplied from the capacitor to the gate terminal.   A series body of a changeover switch (34, 44, 54) and a capacitor (32, 42, 52) for switching between the gate terminal and the collector terminal between energization and de-energization between the gate terminal and the collector terminal. (30, 40, 50) are connected in parallel, the capacitors of the plurality of series bodies have different predetermined capacities, and the larger the current of the primary winding when turning off the transistor, the higher the predetermined The ignition device for an internal combustion engine according to claim 1, wherein the changeover switch connected to a capacitor having a large capacity is switched to energization.   A series body of a changeover switch (34, 44, 54) and a capacitor (32, 42, 52) for switching between the gate terminal and the collector terminal between energization and de-energization between the gate terminal and the collector terminal. (30, 40, 50) are connected in parallel, the capacitors in the plurality of series bodies have different predetermined capacities, and the larger the negative gradient of the current in the primary winding when the transistor is turned off, 2. The ignition device for an internal combustion engine according to claim 1, wherein the changeover switch connected to a capacitor having a large predetermined capacity is switched to energization.   The internal combustion engine ignition device according to claim 1, wherein a resistor (23) having a predetermined magnitude is further connected in series with the capacitor between the gate terminal and the collector terminal.   Between the gate terminal and the collector terminal, a resistor (33, 43, 53) having a predetermined size is connected in series to each of the plurality of series bodies, and the series body having a large predetermined capacity is connected. The ignition device for an internal combustion engine according to claim 2 or 3, wherein the predetermined magnitude is set to be smaller for the connected resistor.   The internal combustion engine ignition device according to claim 1 or 4, wherein a Zener diode (21) having a predetermined breakdown voltage is further connected in series with the capacitor between the gate terminal and the collector terminal.   The Zener diode (31, 41, 51) having a predetermined breakdown voltage is further connected in series with each of the plurality of series bodies between the gate terminal and the collector terminal. An ignition device for an internal combustion engine according to claim 1.

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