JP2011001851A - Internal combustion engine ignition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an electronic control device to accurately detect an abnormal condition.SOLUTION: A temperature detection circuit 14 gives a set signal to a set terminal of a latch circuit 15 when the temperature of an IGBT (Insulated Gate Bipolar Transistor) 13 is above a predetermined value, and the latch circuit 15 gives a cut-off signal to a cut-off circuit 12b. An inverting signal of an ignition signal IGt is given to a reset terminal of the latch circuit 15, and when the ignition signal IGt turns to "L", the latch circuit 15 stops the output of the cut-off signal. An AND gate 19 nullifies the output when a count of a counter circuit 18 amounts to a predetermined value or more, so that even if a detection signal of a current I1 is input from a fail detecting circuit 10, a fail signal IGf is not output during predetermined time or more. An ECU 5 detects the missing of the fail signal IGf.

Description

  The present invention relates to an internal combustion engine ignition device that transmits an ignition state of a spark plug to an electronic control device by responding to an ignition state signal when an ignition signal is input from an electronic control device.

  The internal combustion engine ignition device receives an ignition signal from an electronic control unit (hereinafter referred to as an ECU (Electronic Control Unit)) in a circuit block of the igniter, and returns a fail signal (corresponding to an ignition state signal) from the circuit block to the ECU. (For example, refer to Patent Document 1). According to the technical idea described in Patent Document 1, when the igniter receives an ignition signal, the ignition plug is ignited, and a fail signal corresponding to the ignition state is returned to the ECU.

  A specific example of this type of circuit is shown in FIG. As shown in FIG. 13, the internal combustion engine ignition device 101 connects an igniter 102, an ignition coil 3, and a diode 4 in the illustrated form, energizes the ignition coil 3 based on an ignition signal IGt from the ECU 5, and an ignition plug 6 Spark.

  The igniter 2 is provided with an IGBT (corresponding to a switching element) and a diode (not shown) for detecting the temperature inside the IGBT. By utilizing the Vf temperature characteristic of the diode, If it is determined that there is, the gate drive of the IGBT is cut off. This gate drive cutoff function is referred to as a lock energization prevention function (abbreviation: lock prevention). When this lock prevention function is activated, the temperature of the IGBT can be lowered to prevent overheating destruction of the IGBT. Can do.

  FIG. 14 is a timing chart showing the basic operation at this time. As shown in FIG. 14, when the ECU 5 outputs the ignition signal IGt to the igniter 2 with a predetermined duty ratio, the current I1 energized to the IGBT is detected, and the fail signal IGf is output to the ECU 5 based on the detection result (( 0)).

  In this case, when the duty ratio of the ignition signal IGt is large, the time during which the ignition signal IGt is “H” (corresponding to the on-ignition signal) becomes longer, and the energization time of the IGBT becomes longer. Since the energization time of the current I1 becomes longer, the temperature of the IGBT becomes higher. Then, it is determined that the temperature of the IGBT is overheated in accordance with the decrease in Vf of the built-in diode of the IGBT (see timing (1)). If the igniter 2 determines that the temperature is excessively high, the current I1 flowing through the IGBT is stopped by interrupting the driving of the gate of the IGBT. Thereby, the energization destruction of IGBT can be prevented.

  Thereafter, the ECU 5 sets the ignition signal IGt to “L” (corresponding to the off ignition signal) to reset the lock energization prevention function (see (2)), and the igniter 102 returns to the normal operation mode. Thereafter, when the ignition signal IGt is periodically input, if the IGBT temperature is determined not to be excessively high according to the Vf voltage of the diode, normal operation is performed (see (3)). In this case, the ECU 5 can recognize that the igniter 102 is in the normal operation mode by periodically inputting the fail signal IGf from the igniter 102.

JP-A-8-128381

  However, as shown in FIG. 14, when the off signal of the ignition signal IGt is input, the energization cut-off state is canceled (see (2)). Therefore, when the on ignition signal is continuously input thereafter (3) Since the IGBT is energized, the fail signal IGf is continuously output to the ECU 5, and the ECU 5 regards the igniter 2 as operating normally.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an internal combustion engine ignition device in which an electronic control device can accurately detect an abnormal state.

  According to the first aspect of the invention, the operation is as follows. For example, in the normal state, the ignition state output unit detects a current when the switching element is energized and outputs an ignition state signal corresponding to the detected current to the electronic control unit. During normal operation, the temperature of the switching element operates at a temperature lower than a predetermined value and does not reach the overheated temperature, so that the normal operation is transmitted to the electronic control unit.

The energization cut-off holding unit cuts off the energization to the switching element by the drive unit when the temperature of the switching element detected by the temperature detection unit becomes a predetermined value or more. Thereby, the switching element can be protected from excessive temperature rise.
The release unit releases the energization cut-off state on condition that an off-ignition signal is input from the electronic control device when the energization cut-off holding unit is held, so that normal operation can be continued thereafter. Become.

  Since the ignition state output unit does not output an ignition state signal to the electronic control unit when the number of times the temperature detection value of the temperature detection unit exceeds the predetermined value, the ignition state signal is not output to the electronic control unit when the condition is satisfied. The status signal is not transmitted. As a result, the electronic control unit does not detect the ignition state signal, and the electronic control unit can accurately detect the abnormal state.

  According to the second aspect of the present invention, for example, in the normal state, the ignition state output unit detects a current when the switching element is energized and outputs an ignition state signal corresponding to the detected current to the electronic control unit. The operation can be transmitted to the electronic control unit. When the temperature of the switching element detected by the temperature detection unit exceeds a predetermined value, the energization cutoff holding unit cuts off the energization of the switching element by the drive unit, and thus can protect the switching element from excessive temperature rise.

The release unit releases the energization cut-off state on condition that an off-ignition signal is input from the electronic control device when the energization cut-off holding unit is held, so that normal operation can be continued thereafter. Become. In the state where the power supply interruption holding part is held by the power supply interruption holding part under the condition that the count number of the counting part is equal to or greater than the predetermined number, even if an off ignition signal is given from the electronic control unit, the electric conduction interruption state is not released. I have to. For this reason, the energization interruption state of the switching element is continued.
Therefore, since the ignition state output unit does not detect the energization current of the switching element, the ignition state signal is not output to the electronic control unit. As a result, the electronic control unit does not detect the ignition state signal, and the abnormal state can be accurately detected.

  According to the invention of claim 3, the duty ratio detection unit detects the duty ratio between the on ignition signal and the off ignition signal input from the electronic control circuit, but the release unit has a predetermined duty ratio of the duty ratio detection unit. When the off-ignition signal is given from the electronic control unit when the energization interruption is held by the energization interruption holding unit under the condition that exceeds the value, the energization interruption state is not released, so the energization interruption to the switching element The state can be continued. For this reason, the ignition state signal is not output to the electronic control unit. Thereby, the electronic control unit can accurately detect the abnormal state.

The circuit diagram which shows the structure of the principal part about the 1st Embodiment of this invention Block diagram schematically showing the circuit configuration of an internal combustion engine ignition device Illustration of constant current circuit Illustration of basic operation of igniter Timing chart showing how each signal changes Circuit block diagram of an igniter shown for the second embodiment of the present invention Figure equivalent to FIG. Circuit block diagram of an igniter shown for the third embodiment of the present invention Circuit diagram of duty detection circuit Timing chart showing operation of duty detection circuit Schematic explanatory diagram of the duty ratio determination method Figure equivalent to FIG. FIG. 2 equivalent diagram showing a conventional example Figure equivalent to FIG.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In addition, about the part which has the same function or the similar function demonstrated in the background art column, the same code | symbol is attached | subjected and demonstrated.
FIG. 2 is a schematic block diagram showing the overall configuration of the internal combustion engine ignition device. As shown in FIG. 2, the internal combustion engine ignition device 1 includes an igniter 2, an ignition coil 3, a diode 4, and the like. The internal combustion engine ignition device 1 is operated by a battery + B (power supply voltage), receives an ignition signal IGt from an ECU (Electronic Control Unit) 5 and energizes the ignition coil 6 to generate a spark and use it as fuel. It is supposed to ignite.

  The igniter 2 mainly includes an overvoltage protection circuit 7, a lock prevention circuit 8, an input circuit (waveform shaping circuit) 9, a fail detection circuit 10, an overcurrent protection circuit 11, and a drive circuit 12. The igniter 2 is configured by connecting an IGBT (Insulated Gate Bipolar Transistor) 13 as a driving switching element to a drive circuit 12. The igniter 2 is mainly composed of a semiconductor integrated circuit device and an IGBT 13.

  The primary coil of the ignition coil 3 and the IGBT 13 are connected in series between the battery power source + B and the ground GND, and the IGBT 13 drives and controls the energization timing of the primary current of the ignition coil 3. Between the battery + B and the ground GND, a secondary coil of the ignition coil 3, a diode 4 connected in the reverse direction, and a spark plug 6 are connected in series.

  When the drive circuit 12 turns on the IGBT 13, the current I1 flows through the primary coil of the ignition coil 3, and when the drive circuit 12 turns off the current I1 flowing through the primary coil of the ignition coil 3 is cut off. When a secondary current flows through the ignition coil 3, the spark plug 6 is ignited by being discharged to the spark plug 6.

  FIG. 1 shows the internal circuit configuration of the internal combustion engine ignition device. As shown in FIG. 1, the ignition signal IGt of the ECU 5 is input to the input circuit 9. The input circuit 9 is provided as a waveform shaping circuit that shapes the ignition signal IGt, and outputs the waveform-shaped signal to the lock prevention circuit 8. The lock prevention circuit 8 outputs a cutoff signal to the cutoff circuit 12b of the drive circuit 12 based on the ignition signal IGt and the temperature detection signal of the IGBT 13.

  The drive circuit 12 includes a driver main circuit 12a as a drive unit and a cutoff circuit 12b connected to the driver main circuit 12a. In the normal state, the ignition signal IGt is given to the driver main circuit 12a, and the gate of the IGBT 13 is driven according to the given ignition signal IGt. When the gate of the IGBT 13 is driven, the ignition coil 3 is energized on and off, and the spark plug 6 sparks.

The cutoff circuit 12b is composed of, for example, a switching element connected between the output of the driver main circuit 12a and the ground, and a cutoff signal is given to the cutoff circuit 12b during driving of the IGBT 13 by the driver main circuit 12a. Then, the interruption circuit 12b interrupts the driving state of the IGBT 13.
The lock prevention circuit 8 includes a temperature detection circuit 14 as a temperature detection unit, a latch circuit 15 as a release unit, an OR gate 16, a NOT gate 17, a counter circuit 18 as a count unit, an AND gate 19, and a constant current circuit 20. ing. The temperature detection circuit 14 detects the temperature by detecting Vf of the diode D1 (see FIG. 3) built in the IGBT 13.

  FIG. 3 shows an example of electrical connection between the temperature detection circuit and the IGBT built-in diode. As shown in FIG. 3, a current source Ir and a plurality of diodes D1 are connected in series between the power source and the ground, and a common connection point N1 between the current source Ir and the plurality of diodes D1 has a temperature. It is connected to the detection circuit 14. In a normal state, a constant first current flows through the current source Ir. When the ambient temperature of the diode D1 increases, the Vf of the diode D1 decreases.

  The temperature detection circuit 14 detects a change in Vf of the diode D1 by detecting the voltage at the common connection point N1. Thereby, a temperature change can be detected. The constant current circuit 20 is controlled to decrease the current value of the current source Ir on the condition that the voltage at the common connection point N1 is equal to or lower than a predetermined voltage, and the voltage at the common connection point N1 is equal to or higher than the predetermined voltage. Is controlled to increase the current value of the current source Ir.

  As shown in FIG. 1, the temperature detection signal of the temperature detection circuit 14 is input to the set terminal of the latch circuit 15. The temperature detection circuit 14 determines that the temperature of the IGBT 13 is equal to or higher than the predetermined temperature (overheated) on the condition that the voltage at the common connection point N1 is lower than a predetermined threshold voltage Vref (overheated threshold level), and latches the latch. A set signal “H” is output to the set terminal of the circuit 15.

  On the other hand, the output signal of the input circuit 9 is input to the NOT gate 17, and the output of the NOT gate 17 is input to the OR gate 16. A power-off instruction signal is input to the OR gate 16, and the output of the OR gate 16 is input to the reset terminal of the latch circuit 15. Therefore, the ignition signal IGt is inputted to the reset terminal of the latch circuit 15 through the input circuit 9 and the NOT gate 17 unless a power-off instruction signal is given to the OR gate 16. The Q output of the latch circuit 15 is input to the drive circuit 12 and also supplied to the counter circuit 18. The output of the counter circuit 18 is given to the AND gate 19 in an inverted state.

  The fail detection circuit 10 detects a current I1 flowing through the IGBT 13 and outputs a signal to the AND gate 19 based on the current detection signal. The output of the AND gate 19 is input to the ECU 5 as a fail signal IGf.

FIG. 4 schematically shows the basic operation of the igniter. As shown in FIG. 4, when the ECU 5 gives the ignition signal IGt to the igniter 2, the gate voltage VG of the IGBT 13 rises through the delay time of each block, and passes between the collector and emitter of the IGBT 13 to the primary side of the ignition coil 3. An energization current begins to flow (at the time point (A)). At this time, the collector voltage V1 of the IGBT 13 decreases instantaneously. The energizing current gradually increases in proportion to time.
The energization current I1 between the collector and the emitter of the IGBT 13 gradually increases in proportion to time and reaches a certain first threshold current Iref1 (time (B)). Then, the fail detection circuit 10 detects that the current I1 has reached the first threshold current Iref1, and inverts and outputs the digital fail signal IGf from “H” to “L”.

Thereafter, the conduction current I1 between the collector and the emitter of the IGBT 13 gradually increases in proportion to the time from the first threshold current Iref1, and reaches the second threshold current Iref2 (time point (C)). Then, the fail detection circuit 10 inverts the digital fail signal IGf from “L” to “H” and outputs it.
By performing such a basic operation, the igniter 2 outputs to the ECU 5 a pulse-like fail signal IGf that becomes an ignition state signal of the spark plug 6 when the energizing current I1 flows. Therefore, the ECU 5 can detect the energized state of the IGBT 13 and the ignition state of the spark plug 6 by receiving the fail signal IGf periodically and periodically within a predetermined period.

Next, characteristic portions according to this embodiment will be described with reference to FIG. In FIG. 5, a signal indicated by a dotted line is a waveform drawn for easy understanding of the explanation, and is not actually output.
FIG. 5 shows a schematic operation of the circuit shown in FIG. 1 by a timing chart. As shown in FIG. 5, the ECU 5 outputs a rectangular wave ignition signal IGt having a predetermined duty ratio corresponding to the engine speed (see FIG. 5A).

When the ignition signal IGt is given to the gate of the IGBT 13 through the driver main circuit 12a of the drive circuit 12 (see the gate output in FIG. 5D), the IGBT 13 drives the ignition coil 3.
When the ignition signal IGt shifts to the “H” state (corresponding to an on ignition signal) and the ignition coil 3 is energized from the battery power source + B (see (10) in FIG. 5), a current is supplied to the primary side of the ignition coil 3. I1 flows and current I1 begins to flow through the IGBT 13 (see FIG. 5E).

  The fail detection circuit 10 detects this current I1 and outputs an “L” signal as an ignition state signal when the current Iref1 is equal to or larger than the predetermined current Iref1 and equal to or smaller than the predetermined current Iref2 (see (11) in FIG. 5F). In the initial state, the count number of the counter circuit 18 is 0, so the output of the counter circuit 18 is held in the “L” state. Since the inverted signal of the output of the counter circuit 18 is input to the AND gate 19, the AND gate 19 is enabled (enabled). Therefore, the output of the fail detection circuit 10 is directly output to the ECU 5 as the fail signal IGf through the AND gate 19.

  When the current I1 continues to flow through the IGBT 13, the temperature of the IGBT 13 rises. When the temperature of the IGBT 13 rises, Vf of the built-in diode D1 of the IGBT 13 falls, thereby lowering the voltage at the common connection point N1 (see FIG. 5B). The temperature detection circuit 14 determines that the voltage at the common connection point N1 is lower than the predetermined temperature while detecting that the voltage at the common connection point N1 is higher than the threshold voltage Vref, and gives an “L” signal to the set terminal of the latch circuit 15. .

  When the voltage at the common connection point N1 becomes equal to or lower than the predetermined voltage Vref, the temperature detection circuit 14 determines that the temperature of the IGBT 13 is equal to or higher than the predetermined temperature, and the temperature detection circuit 14 sets the output to the “H” state (FIG. 5 ( c) (12)). At the same time, the constant current circuit 20 reduces the conduction current of the current source Ir to the second current. Then, the temperature detection circuit 14 is detected in a state where the input voltage (the voltage at the common connection point N1) is further lower than the threshold voltage Vref (see (12) in FIG. 5B).

  When the “H” signal, which is the output signal of the temperature detection circuit 14, is input to the set terminal, the latch circuit 15 holds the Q output in the “H” state (see (12) in FIG. 5 (g)). The signal is output to the cutoff circuit 12b of the drive circuit 12. When this Q output is input, the cutoff circuit 12b cuts off the signal from the driver main circuit 12a to the IGBT 13 and puts the gate output to the IGBT 13 in the energization cutoff state ("L" state) ((d) in FIG. 12) See and after).

  When the cut-off circuit 12b cuts off the drive signal from the driver main circuit 12a to the gate of the IGBT 13 and maintains the energization cut-off state, the current I1 does not flow through the IGBT 13. During this time, since the fail detection circuit 10 does not detect the current I1, the fail signal IGf is also not output (see the dotted line portion in (13) of FIG. 5).

  For example, if the ECU 5 can detect the absence of the fail signal IGf, the abnormal state on the igniter 2 side can be detected, but the ECU 5 can determine the abnormal state with reliability by detecting a plurality of times within a predetermined time, for example. In some cases, the ECU 5 cannot detect a missing part due to some influence. Therefore, in the present embodiment, the problem is solved by providing the counter circuit 18. The counter circuit 18 counts the number of times that the energization cut-off state is reached by counting the rising signal of the output of the latch circuit 15 that the temperature of the IGBT 13 becomes equal to or higher than a predetermined temperature (see (12) in FIG. 5 (i)). ).

When the current I1 is not passed through the IGBT 13, the temperature of the IGBT 13 decreases. As Vf of the built-in diode D1 of the IGBT 13 gradually increases, the input voltage (voltage at the common connection point N1) of the temperature detection circuit 14 also gradually increases (see (12) and (13) in FIG. 5B). .
When the voltage at the common connection point N1 becomes equal to or higher than the threshold voltage Vref, the temperature detection circuit 14 holds the output in the “L” state (see (14) in FIGS. 5B and 5C). Although this output is input to the set terminal of the latch circuit 15, since the input of the reset terminal of the latch circuit 15 is in the “L” state, the energization is cut off by holding the Q output in the “H” state. Keep holding.

At this time, since the constant current circuit 20 increases the control current value of the current source Ir from the second current to the first current, the voltage at the common connection point N1 detected by the temperature detection circuit 14 is steep. It rises (see (14) in FIG. 5B).
Thereafter, when the ignition signal IGt is in the “L” state (corresponding to the off ignition signal), the inverted signal (“H” signal) is input to the reset terminal of the latch circuit 15, and the latch circuit 15 L "signal is output (see (15) in FIG. 5 (g)). As a result, the latch circuit 15 stops outputting the cutoff signal. When the cutoff signal is not input from the latch circuit 15 to the cutoff circuit 12b, the driver main circuit 12a can re-output the drive signal to the gate of the IGBT 13. In this way, the energization cut-off state is canceled and the normal state is entered.

  Thereafter, when the ignition signal IGt is input to the igniter 2, the driver main circuit 12a normally drives the gate of the IGBT 13 unless the input voltage of the temperature detection circuit 14 becomes equal to or lower than the threshold voltage Vref. At this time, the fail signal IGf is normally output to the ECU 5 (see (16) in FIG. 5).

  Thereafter, when the temperature detection circuit 14 detects that the voltage of the common connection point N1 is equal to or lower than the threshold voltage Vref, thereby detecting that the temperature of the IGBT 13 is equal to or higher than the predetermined temperature, the set terminal of the latch circuit 15 is again connected. The “H” signal is input, and the output of the temperature detection circuit 14 shifts to the “H” state again (see (17) in FIG. 5). In this case, the same control as described above is performed, but the counter circuit 18 counts the rising signal of the latch circuit 15 and determines whether or not it is a predetermined number of times (for example, twice) or more. In this case, the output of the counter circuit 18 is set to the “H” state (see (17) in FIG. 5 (h)).

  Since the inverted signal of the output of the counter circuit 18 is input to the AND gate 19, the AND gate 19 is disabled (disabled). Thereafter, the AND gate 19 does not output the fail signal IGf to the ECU 5 even if the detection signal of the current I1 is input from the fail detection circuit 10 (see (18) in FIG. 5 (i)). Since the missing state of the fail signal IGf continues for a predetermined time or longer, the ECU 5 can accurately detect the missing of the fail signal IGf.

  According to the present embodiment, the AND gate 19 invalidates the output when the count number of the counter circuit 18 exceeds a predetermined number, and even if the detection signal of the current I1 is input from the fail detection circuit 10, the fail signal IGf is set for a predetermined time or more. Since no output is made, the ECU 5 can accurately detect that an abnormality has occurred in the igniter by detecting the absence of the fail signal IGf.

(Second Embodiment)
6 and 7 show a second embodiment of the present invention. The difference from the previous embodiment is that the number of times that the temperature of the switching element has reached a predetermined value or more is a predetermined number of times or more. In the case of satisfying, even if an off ignition signal is inputted, the energization cut-off state is not released. The same parts as those of the above-described embodiment are denoted by the same reference numerals, description thereof is omitted, and different parts will be described below.

  FIG. 6 shows a circuit configuration by a schematic block diagram. As shown in FIG. 6, the lock prevention circuit 21 includes a temperature detection circuit 14, a latch circuit 15, an OR gate 16, and a NOT gate 17. Instead of the counter circuit 18 and the AND gate 19, an AND gate 22, A counter circuit 23 serving as a count unit is provided.

  The output of the temperature detection circuit 14 is input to the counter circuit 23. The output of the counter circuit 23 is given to the inverting input of the AND gate 22. The output of the NOT gate 17 is given to the input of the AND gate 22. The lock prevention circuit 21 is configured by such a connection relationship. Note that the fail detection circuit 10 described in the above-described embodiment functions as an ignition state output unit in the embodiments after this embodiment, and the output of the fail detection circuit 10 is directly input to the ECU 5 as a fail signal IGf. Has been.

  The count number of the counter circuit 23 is 0 in the initial state. In this case, the counter circuit 23 outputs “L”, and outputs “H” when counting a predetermined number of times or more.

  FIG. 7 schematically shows a timing chart. For example, when the duty ratio of the ignition signal IGt is large, the energization time of the IGBT 13 becomes long, the temperature of the IGBT 13 rises, and the Vf of the built-in diode of the IGBT 13 falls. The voltage at the common connection point N1 decreases and becomes equal to or lower than the threshold voltage Vref. Since the output of the temperature detection circuit 14 is in the “H” state and the set terminal of the latch circuit 15 is in the “H” state, the Q output of the latch circuit 15 is also in the “H” state. When the Q output of the latch circuit 15 becomes “H”, the energization current I1 of the IGBT 13 is cut off and the output of the fail signal IGf is stopped (see (21) in FIG. 7).

  At the same time, “H” is also given to the counter circuit 23, and the counter circuit 23 counts “one time”, but the counter circuit 23 counts “L” because the count number is less than a predetermined number (for example, three times). "H" is continuously input to the AND gate 22. As a result, the AND gate 22 continues to output the inverted signal of the ignition signal IGt.

Thereafter, when the voltage at the common connection point N1 becomes equal to or higher than the threshold voltage Vref due to an increase in Vf of the built-in diode of the IGBT 13, the temperature detection circuit 14 outputs “L” to the set terminal of the latch circuit 15, but the ignition signal Since IGt is in the “H” state, “L” is continuously input to the reset terminal of the latch circuit 15, and the output of the latch circuit 15 is held at “H” (see (22) in FIG. 7).
Thereafter, when the ignition signal IGt becomes the “L” state (corresponding to the off ignition signal), the “H” signal is given to the reset terminal of the latch circuit 15. When the output of the latch circuit 15 becomes “L”, the energization interruption by the lock prevention circuit 21 is once released, and the energization interruption state is released (see (23) in FIG. 7).

Thereafter, the rising signal (“H” signal) of the ignition signal IGt causes the current I1 to flow through the IGBT 13 (see (24) in FIG. 7), and the fail signal IGf is output ((25) in FIG. 7). reference).
Thereafter, these operations are performed every time the ignition signal IGt is repeatedly turned on and off, and the counter circuit 23 counts each time the output of the temperature detection circuit 14 transitions from “L” to “H” (FIG. 7). (Refer to (26)).

  For example, when the counter circuit 23 counts a predetermined number of times (for example, three times) or more, “H” is given to the inverting input of the AND gate 22, and therefore “L” is given to the input of the AND gate 22, and The operation of the gate 22 is invalidated, and the output of the AND gate 22 is always “L” regardless of the change of the ignition signal IGt. Therefore, “L” is always given to the reset terminal of the latch circuit 15 unless the power-off instruction signal is given. The latch circuit 15 always continues to provide the “H” signal as the cutoff signal to the cutoff circuit 12b (see (27) and thereafter in FIG. 7).

  Since the driver main circuit 12a does not drive the gate of the IGBT 13 even when the ignition signal IGt is given from the ECU 5 to the igniter 2, the current I1 does not flow through the IGBT 13. The fail detection circuit 10 does not detect the current I1 flowing through the IGBT 13, and therefore does not output the fail signal IGf to the ECU 5. Therefore, the ECU 5 can accurately detect the abnormal state of the igniter by detecting the absence of the fail signal IGf.

  According to the present embodiment, the counter circuit 23 counts the number of times the output of the temperature detection circuit 14 transitions from the “L” state to the “H” state, and the latch circuit 15 satisfies the condition that the count number is equal to or greater than a predetermined number. Since the cut-off signal is continuously applied to the cut-off circuit 12b below, the energization cut-off state continues. Therefore, the ECU 5 can easily detect the lack of the fail signal IGf. Therefore, the ECU 5 can accurately detect the abnormal state of the igniter.

(Third embodiment)
8 to 12 show a third embodiment of the present invention. The difference from the previous embodiment is that the duty ratio between the on-ignition signal and the off-ignition signal by the electronic control device is not less than a predetermined value. Is set to the condition that the lock cannot be released, and when the condition that the lock cannot be released is satisfied, even when the off ignition signal is input, the energization cut-off state is not released. The same parts as those of the above-described embodiment are denoted by the same reference numerals, description thereof is omitted, and different parts will be described below.

  FIG. 8 schematically shows a circuit configuration. As shown in FIG. 8, the lock prevention circuit 24 includes the temperature detection circuit 14, the latch circuit 15, the OR gate 16, the NOT gate 17, and the AND gate 22 described in the above embodiment, and a duty ratio detection unit. The detection circuit 25 is connected to the inverting input of the AND gate 22.

  FIG. 9 shows a specific configuration of the duty detection circuit. As shown in FIG. 9, the duty detection circuit 25 includes transistors Tr1 to Tr3 (Tr1, Tr3 are NPN type, Tr2 is PNP type), constant current sources Ia1 to Ia3, a capacitor C1, and a comparator CP1. ing.

  A constant current source Ia1 and the collector-emitter of the transistor Tr1 are connected in series between the power supply node N0 and the ground. An ignition signal IGt is input to the base of the transistor Tr1. The bases of the transistors Tr2 and Tr3 are commonly connected to a common connection node N2 between the constant current source Ia1 and the collector of the transistor Tr1.

  The constant current source Ia2, the emitter-collector of the transistor Tr2, the collector-emitter of the transistor Tr3, and the constant current source Ia3 are connected in series between the power supply node N0 and the ground. A capacitor C1 is connected between the common connection node N3 between the collectors of the transistors Tr2 and Tr3 and the ground.

  The capacitor C1 has a function for monitoring the duty ratio. The charging voltage of the capacitor C1 is given to the non-inverting input terminal of the comparator CP1. The reference voltage Vr is applied to the inverting input terminal of the comparator CP1, and the comparator CP1 compares the voltage at the node N3 with the reference voltage Vr, and uses the comparison result as the output of the duty detection circuit 25.

When the “H” signal of the ignition signal IGt is input to the base of the transistor Tr1, the transistor Tr1 is turned on and draws a current flowing through the constant current source Ia1. Accordingly, since the voltage at the node N2 decreases, the accumulated charge of the capacitor C1 increases and the voltage across the capacitor C1 increases.
Conversely, when the “L” signal of the ignition signal IGt is input to the base of the transistor Tr1, the transistor Tr1 is turned off and the voltage at the node N2 increases. Then, the charge of the capacitor C1 is discharged from the constant current source Ia3 through the transistor Tr3.

FIG. 10 transiently shows the operation of the duty detection circuit according to the duty ratio, and FIG. 11 shows the voltage of the node N3 in comparison with the reference voltage.
As shown in FIG. 10, when the duty ratio of the ignition signal IGt is relatively low (for example, 20%), the voltage at the node N3 (the voltage across the capacitor C1) is the charged charge while being repeatedly charged and discharged. Are discharged, the voltage at the node N3 does not exceed the reference voltage Vr, and the output of the comparator CP1 remains “L”.

  When the duty ratio of the ignition signal IGt is relatively high (for example, 50%), the voltage at the node N3 (the voltage across the capacitor C1) gradually increases while repeating charging and discharging, and the voltage at the node N3 is increased for a predetermined time t1. When the time has elapsed, the voltage becomes equal to or higher than the reference voltage Vr. The duty detection circuit 25 outputs “H” when the duty ratio exceeds a predetermined value and continues for a predetermined time.

FIG. 12 schematically shows a timing chart. Consider the case where an ignition signal IGt having a relatively high duty ratio is input as shown in FIG.
Time range t1 from the time when the input of the ignition signal IGt “H” starts (see (31) in FIG. 12) to the time when the output of the duty detection circuit 25 reaches the “H” state (see (33) in FIG. 12). As shown in the above-described embodiment, when the ignition signal IGt changes from “H” to “L”, “H” is input to the reset terminal of the latch circuit 15, and therefore the Q output of the latch circuit 15 is “L”. (See (32) of FIG. 12), the fail detection circuit 10 outputs the fail signal IGf to the ECU 5 thereafter. However, when the duty detection circuit 25 detects a duty ratio greater than or equal to a predetermined value for a predetermined time or more, the duty detection circuit 25 outputs an “H” signal (see (33) in FIG. 12).

  Thereafter, when the temperature detection circuit 14 detects the voltage at the common connection point N1 as a predetermined voltage Vref or less and outputs an “H” signal to the set terminal of the latch circuit 15, the latch circuit 15 outputs an “H” signal as a cutoff signal. It outputs to the interruption | blocking circuit 12b (refer (34) of FIG. 12). At this time, since the output of the AND gate 22 is held at “L” and “L” is input to the reset terminal of the latch circuit 15, even if the ignition signal IGt becomes “L”, the latch circuit 15 Does not stop the output of the cutoff signal, and the energization cutoff state is not released (see (35) in FIG. 12).

  The driver main circuit 12a does not drive the gate of the IGBT 13 even when the ignition signal IGt is given from the ECU 5, so that the current I1 does not flow through the IGBT 13. The fail detection circuit 10 does not detect the current I1 flowing through the IGBT 13, and therefore does not output a fail signal to the ECU 5. Therefore, the ECU 5 can accurately detect the abnormal state of the igniter by detecting the absence of the fail signal IGf.

Other operations are the same as those of the previous embodiment. Therefore, according to the present embodiment, the duty detection circuit 25 detects that the duty ratio of the ignition signal IGt is equal to or greater than a predetermined value, and the latch circuit 15 is in the “L” state when the condition is satisfied. Even if it becomes, the interruption signal is continuously given to the interruption circuit 12b. For this reason, the energization cut-off state continues and the ECU 5 can detect the absence of the fail signal IGf. Therefore, the ECU 5 can accurately detect the abnormal state on the igniter 2 side.
The switching element is not limited to the IGBT 13.

  In the drawings, 1 is an internal combustion engine ignition device, 5 is an ECU (electronic control unit), 6 is a spark plug, 12a is a driver main circuit (drive unit), 12b is a transistor (energization cutoff holding unit), and 13 is an IGBT (switching element). ), 14 is a temperature detection circuit (temperature detection unit), 15 is a latch circuit (release unit), 18 and 23 are counter circuits (count units), 25 is a duty detection circuit (duty ratio detection unit), and Z is an ignition state output. Indicates the part.

Claims (3)

When the on-ignition signal is input from the electronic control unit, the ignition element is energized by energizing the switching element, and when the off-ignition signal is input from the electronic control unit, the switching element is de-energized. A drive unit that is de-energized,
An ignition state output unit that detects a current when the switching element is energized and outputs an ignition state signal corresponding to the detected current to the electronic control unit;
A temperature detector for detecting the temperature of the switching element;
When the temperature detection value by the temperature detection unit is equal to or higher than a predetermined temperature, an energization interruption holding unit that interrupts and holds energization to the switching element by the drive unit,
A release unit that releases the energization cut-off state when an off-ignition signal is input from the electronic control device when the energization cut-off holding unit is held.
The ignition state output unit is configured not to output an ignition state signal to the electronic control unit when the number of times the temperature detection value of the temperature detection unit is equal to or higher than a predetermined temperature is greater than or equal to a predetermined number. Internal combustion engine ignition device. When an on ignition signal is input from the electronic control unit, the switching element is energized to energize the ignition coil, and when an off ignition signal is input from the electronic control unit, the switching element is de-energized to A non-energized drive unit;
An ignition state output unit that detects a current when the switching element is energized and outputs an ignition state signal corresponding to the detected current to the electronic control unit;
A temperature detector for detecting the temperature of the switching element;
When the temperature detection value by the temperature detection unit is equal to or higher than a predetermined temperature, an energization interruption holding unit that interrupts and holds energization by the drive unit;
A release unit for releasing the energization cut-off state when an off-ignition signal is input from the electronic control device when the energization cut-off holding unit is held by the electronic cut-off holding unit;
A count unit that counts the number of times the temperature detection value by the temperature detection unit has reached a predetermined value or more,
The release unit is energized when an off-ignition signal is given from the electronic control unit when the energization interruption holding unit is held by the energization interruption holding unit under the condition that the count of the count unit is a predetermined number or more. An internal combustion engine ignition device characterized in that the shut-off state is not released. When an on ignition signal is input from the electronic control unit, the switching element is energized to energize the ignition coil, and when an off ignition signal is input from the electronic control unit, the switching element is de-energized to A non-energized drive unit;
An ignition state output unit that detects a current when the switching element is energized and outputs an ignition state signal corresponding to the detected current to the electronic control unit;
A temperature detector for detecting the temperature of the switching element;
When the temperature detection value by the temperature detection unit is equal to or higher than a predetermined temperature, an energization interruption holding unit that interrupts and holds energization by the drive unit;
A release unit for releasing the energization cut-off state when an off-ignition signal is input from the electronic control device when the energization cut-off holding unit is held.
A duty ratio detection unit that detects a duty ratio between an on ignition signal and an off ignition signal input from the electronic control unit;
The release unit is configured to receive an off-ignition signal from the electronic control unit when the energization interruption holding unit is held by the energization interruption holding unit under a condition that the duty ratio of the duty ratio detection unit is a predetermined value or more. An internal combustion engine ignition device characterized in that the energization cut-off state is not released.

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