JP2017150345A - Ignition device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition device for an internal combustion engine that is normally operated in response to an ignition signal for performing a high frequency multiple ignition or multiple ignition and at the same time prevents damage caused by an electric conduction for an extended period.SOLUTION: This invention comprises: a switch element 7 for generating a secondary voltage by electrical conduction and cutting-off of a primary current flowing from a power supply 5 to a primary coil 61 in response to an ignition signal from an ECU externally connected; a timer circuit 12 for detecting a length of electric conduction time indicated by the ignition signal; and a self-shutoff circuit 15 for controlling the switch element 7 in response to an output voltage of the timer circuit 12 and stopping electric conduction of the primary current. The timer circuit 12 comprises a charging circuit for accumulating electric load during electrical conduction time indicated by the ignition signal and an electrical discharging circuit for discharging the accumulated load during the shutoff time indicated by the ignition signal. The electrical discharging circuit has a time constant at the time of electrical discharging that is lower than a time constant at the time of electrical charging held by the electrical charging circuit and operates the self-shutoff circuit 15 when the accumulated load exceeds a specified amount.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ignition device provided in an ignition coil for an internal combustion engine.

In particular, since an internal combustion engine mounted on an automobile or the like frequently changes in rotation speed, an ignition coil that generates a high voltage during an ignition stroke also frequently changes a generation interval of the high voltage.
For this reason, the heat generated by the ignition device (igniter) provided in the ignition coil repeatedly increases and decreases, which may accelerate the damage or deterioration of circuit elements constituting the ignition device. It can happen.
Therefore, in order to prevent the occurrence of troubles due to the heat generation and the like, some ignition devices are provided with a current control circuit and an overheat detection circuit.

The ignition device includes a counter that operates in response to an ignition signal from an engine control unit (hereinafter referred to as ECU), and is configured to detect energization for a predetermined time or more using the counter ( For example, see Patent Document 1).
The circuit for detecting energization for a long time is constituted by a CR circuit using a resistor and a capacitor. Since such a CR circuit has a time constant, when a spark discharge is generated in the spark plug for a long time or a plurality of times according to the operating state or combustion state of the internal combustion engine, Circuit operation may not be supported.

JP 2014-118855 A

In order to improve the combustion state of the internal combustion engine, the ignition device operates by following the high-frequency multi-ignition signal and multi-ignition signal output from the ECU, and generates a high voltage that continues multiple times or for a predetermined period in the ignition coil. There are existing technologies to make it.
When the ignition device is provided with a long-time energization detection circuit configured by the above-described CR circuit, the time constant of this circuit affects, for example, when a signal level indicating the significance of a pulse signal occurs multiple times in a short period of time, When it continues for a long time, it becomes difficult to perform normal circuit operation.

Specifically, when the above-described long-time energization detection circuit is configured using a CR circuit, when a high-frequency multi-ignition signal or a multi-ignition signal is input from the ECU, electric charges are accumulated in a capacitor in the CR circuit by this signal voltage. The
Therefore, when a high-frequency multi-ignition signal or multiple ignition signal is input to an ignition device having a long-time energization detection circuit or the like, the detection circuit or the like malfunctions, for example, the self-shutoff function operates. There is.
This is an event that occurs because the circuit constant or time constant of the charging time and discharging time of the capacitor constituting the CR circuit is the same.

  The present invention has been made in view of the above problems, and provides an internal combustion engine ignition device that operates normally in response to an ignition signal for performing high-frequency multi-ignition or multiple ignition and prevents damage due to energization for a long time. The purpose is to provide.

  An internal combustion engine ignition device according to the present invention is responsive to an ignition coil that generates a secondary voltage in a secondary coil when a primary current flowing through the primary coil is interrupted, and an ignition signal from an externally connected control means. A switch part for generating the secondary voltage by energizing and interrupting the primary current flowing from the power source to the primary side coil, an energization detecting part for detecting the length of the energization time indicated by the ignition signal, A charging circuit that controls the switch unit according to an output voltage of the energization detection unit and stops energization of the primary current, and the energization detection unit accumulates electric charge during the energization time indicated by the ignition signal. And a discharge circuit that discharges the accumulated electric charge during a cut-off time indicated by the ignition signal, and the discharge circuit has a time constant during discharge that is smaller than a time constant during charge included in the charge circuit. The accumulated charge is equal to or to operate the power supply stop time exceeds a predetermined amount.

  The charging circuit includes a capacitor for storing the charge and a charging resistor connected in series to the capacitor, and the discharging circuit has an anode connected to a connection point between the charging resistor and the capacitor. A bypass diode and a discharge resistor connected to a cathode of the bypass diode, the energization detection unit flows a charging current to the capacitor via the charging resistor according to a level of the ignition signal, When a discharge current flows from a capacitor through the bypass diode and the discharge resistor, the energization stop unit is when the output voltage of the energization detection unit generated at a connection point between the capacitor and the charging resistor becomes a predetermined value or more. The primary current supply is stopped.

  The charging circuit causes the charging current to flow through the capacitor when the ignition signal is at a high level indicating the energization time, and the discharging circuit is configured to discharge the discharge current when the ignition signal is at a low level indicating the cutoff time. Is caused to flow through the discharge resistor to the control means or a portion of the ground potential of the internal combustion engine.

  In addition, when the time constant during charging of the capacitor and the charging resistor is 1, the charging resistor and the discharging resistor are set so that the time constant during discharging of the capacitor and the discharging resistor is 0.02 or less. And the value of the capacitor is set.

  According to the present invention, the ignition coil or the ignition device can be prevented from being damaged due to heat generation, and can be operated in response to a high-frequency multi-ignition signal or a multi-ignition signal input from an ECU or the like.

1 is a circuit diagram showing a schematic configuration of an internal combustion engine ignition device according to Embodiment 1 of the present invention; FIG. It is explanatory drawing which shows operation | movement of the internal combustion engine ignition device of FIG. It is explanatory drawing which shows operation | movement of the ignition device for internal combustion engines which is not provided with the bypass diode. 6 is a circuit diagram illustrating a schematic configuration of an internal combustion engine ignition device according to Embodiment 2. FIG. 6 is a circuit diagram illustrating a schematic configuration of an internal combustion engine ignition device according to Embodiment 3. FIG.

An embodiment of the present invention will be described below with reference to the drawings.
Example 1
1 is a circuit diagram showing a schematic configuration of an internal combustion engine ignition device according to Embodiment 1 of the present invention. The illustrated ignition device 1 includes a constant voltage circuit 11, a timer circuit 12, a self-shutoff circuit 15, and a switch element 7. For example, an IGBT is used for the switch element 7.
The constant voltage circuit 11 is connected to the high potential side electrode of the battery 5 at the input end, and is configured to convert the DC voltage supplied from the battery 5 into a predetermined DC voltage and output it. The output terminal of the constant voltage circuit 11 is connected to a self-shutoff circuit 15.

The high potential side electrode of the battery 5 is connected to one end of the primary side coil 61 of the ignition coil 6. The other end of the primary coil 61 is connected to the collector (switch contact) of the switch element 7. The emitter of the switch element 7 is grounded.
The gate (control terminal) of the switch element 7 is connected to the output terminal of the self-shutoff circuit 15 via the resistor 16, and the ignition signal input from the outside to the ignition device 1 is sent to the self-shutoff circuit 15. The circuit is connected to input via the A resistor 17 that protects the switch element 7 is connected to the gate of the switch element 7. The low potential side electrode of the battery 5 is grounded.
The secondary coil 62 of the ignition coil 6 has one end connected to the head (center) electrode of the spark plug 8 and the other end connected to the ground in the same manner as the outer electrode of the spark plug 8.

  The timer circuit 12 is, for example, a resistor 12a (charging resistor) and a capacitor 12b connected in series. One end of the resistor 12a is connected to an input point of an ignition signal from the outside (such as an ECU), and the capacitor 12b One end is grounded. One end of a resistor 13 (discharge resistor) is connected to one end of the resistor 12a, that is, the input point of the ignition signal of the ignition device 1, and the other end of the resistor 13 is connected to the input end of the self-shutoff circuit 15. And connected to the cathode of the bypass diode 14. The other end of the capacitor 12b is grounded.

  The connection point between the resistor 12a and the capacitor 12b is connected to the anode of the bypass diode 14 and further connected to the input terminal (positive input terminal) of the comparator 151 constituting the self-shutoff circuit 15. Note that a voltage Vref obtained by adjusting the output voltage of the constant voltage circuit 11 using the resistors 15a and 15b is input to the inverting input terminal of the comparator 151. Further, the base of the transistor 153 and the output terminal of the comparator 151 are connected via a resistor or the like so that the output signal of the comparator 151 is supplied to the control terminal (eg, base) of the transistor 153.

Next, the operation will be described.
FIG. 2 is an explanatory view showing the operation of the internal combustion engine ignition device of FIG. This figure shows the ignition signal input from the outside at the top, the output voltage (output signal) of the comparator 151 constituting the self-shutoff circuit 15 at the bottom, the charging voltage of the capacitor 12b at the bottom, and the self-shutoff at the bottom. 6 is a timing chart showing an operating state of the circuit 15 and a primary current flowing through the ignition coil 6 (primary coil 61) at the lowest stage.
Note that the ignition signal exemplified here indicates the energization time during which the primary current is energized when the period is at the high level, and the cutoff time when the primary current is interrupted during the period when the level is low.

When an ignition signal whose voltage level changes with time is input to the input terminal of the ignition device 1, the capacitor 12b of the timer circuit 12 repeats charging and discharging in response to the voltage level change of the ignition signal.
The comparator 151 of the self-shutoff circuit 15 compares the voltage across the capacitor 12b that repeats charging and discharging as described above with the voltage Vref generated from the output voltage of the constant voltage circuit 11, and the voltage across the capacitor 12b is the voltage. As long as it does not exceed Vref, the transistor 153 is turned on, and a pull-up voltage is applied to the gate of the switch element 7 via each resistor. When this pull-up voltage is applied, the function of the self-shutoff circuit 15 (the self-shutoff function shown in FIG. 2 and the like) is off, and an ignition signal (to the gate of the switch element 7 via the comparator 152) The ignition signal at a level that can control the switch element 7) is input.

When the self-shutoff function is in the off state, if the ignition signal input from the outside becomes significant, for example, becomes high level, the switch element 7 is turned on by the output signal of the comparator 152 and the like, and the primary coil 61 is supplied with the primary current. Flows.
Thereafter, when the ignition signal transitions to a low level, the switch element 7 rapidly transitions to the OFF state following the ignition signal, and cuts off the primary current. When the primary current is sharply interrupted, a high voltage (secondary voltage) is excited in the secondary coil 62, and a spark discharge is generated in the spark plug 8 to which this high voltage is applied, so that the ignition stroke of the internal combustion engine is reduced. To be implemented.

Here, the ignition signal supplied to the capacitor 12b is limited to an appropriate voltage level by the resistor 12a or adjusted so as to obtain a charging current having an appropriate magnitude. When the ignition signal output from the control means such as the ECU is at a high level, the capacitor 12b accumulates electric charge through the charging current limited by the resistor 12a as described above.
Further, when the ignition signal is at a low level, the accumulated electric charge is discharged (in the ignition device 1 shown in FIG. 1, the electric charge is discharged via a bypass diode 14 and a resistor 13 as will be described later). Absorb to part (GND part).

  As described above, when the capacitor 12b repeats charging and discharging according to the level transition of the ignition signal, if the ignition signal is maintained at a high level for a longer period than the predetermined period (when an abnormal ignition signal is input), the capacitor 12b As a result, the charge accumulated in the capacitor 12b becomes excessive, and the voltage across the capacitor 12b exceeds the voltage Vref. Then, a signal indicating significance is output from the comparator 151 to the transistor 153. For example, when the output signal of the comparator 151 transits from a low level to a high level indicating significance, the transistor 153 is turned off and the pull-up voltage is not applied.

When the application of the pull-up voltage is stopped, the control terminal voltage of the switch element 7 (the gate voltage in the circuit illustrated in FIG. 1) drops, and the switch element 7 is also turned off without depending on the ignition signal level. The primary current flowing in 61 stops.
That is, the function of the self-shutoff circuit 15 is turned on to stop the ignition operation by the ignition device 1, the ignition coil 6 and the ignition plug 8, and the temperature of the ignition device 1 and the ignition coil 6 is excessively increased. It is preventing.

Here, the internal combustion engine may be operated by high EGR or a lean air-fuel mixture that makes ignition and combustion difficult. For example, in order to increase combustion efficiency during acceleration, etc., depending on the operating state of the internal combustion engine, etc. Some perform high-frequency multi-ignition and multiple ignition.
When performing such an ignition operation, a high-frequency multi-ignition signal that repeats a significant high level (energization time) in a shorter cycle than a normal ignition signal, or a multiple ignition signal that increases the energization time of the primary current is an ECU or the like. Is output from. Specifically, in one ignition stroke, the high-frequency multi-ignition signal, the multiple ignition signal, and the like are shorter in the low level and the discharge time of the capacitor 12b is shorter than the normal ignition signal. .

FIG. 3 is an explanatory diagram showing the operation of the internal combustion engine ignition device that does not include the resistor 13 and the bypass diode 14. This figure relates to the operation of an ignition device having a circuit configuration substantially similar to that of the ignition device 1 of FIG. 1 and not including the bypass diode 14 and the like, and is a timing chart similar to FIG.
As described above, the capacitor 12b is connected to the input terminal of the ignition device 1 via the resistor 12a, and when the resistor 13 and the bypass diode 14 are not provided, the charging current path and the discharging current of the capacitor 12b. In other words, both the charging circuit and the discharging circuit include the resistor 12a. That is, the same time constant affects the charging operation and discharging operation of the capacitor 12b.

When an ignition signal (high-frequency multi-ignition signal or multiple ignition signal) having a low level period (interruption time) shorter than a normal ignition signal is input to such a circuit, the capacitor 12b Charges accumulated during the high level period (energization time) cannot be discharged sufficiently.
Each time charging / discharging is repeated in accordance with the level transition of the ignition signal, the accumulated charge increases and the voltage across the capacitor 12b (“charging voltage” in FIG. 3) increases.
If the voltage across the capacitor 12b exceeds the voltage Vref while charging and discharging are repeated, the self-shutoff circuit 15 is activated (turned on) as described above, and the application of the pull-up voltage is cut off by the output signal of the comparator 151. As a result, the switch operation of the switch element 7 stops and the primary current does not flow to the ignition coil 6.

In the ignition device 1 according to the present invention, when the ignition operation is controlled using the ignition signal having a short low level period, the self-cutoff circuit 15 is not operated as in the case of inputting an abnormal ignition signal. In addition, a bypass diode 14 and a resistor 13 are provided.
When the ignition signal input from the ECU or the like to the ignition device 1 is at a high level, a charging current flows from the ECU or the like to the capacitor 12b via the resistor 12a, and the ignition signal transitions to a low level. Then, a discharge current flows from the capacitor 12b whose voltage at both ends is increased by the charging current.

This discharge current flows in the forward direction through the bypass diode 14 from one end of the capacitor 12b which is at a high potential, and to the ECU or the like where the ignition signal is at a low level (low potential) via the resistor 13. And is absorbed by the ground potential portion of the ECU or the like.
That is, the charging current flows through the resistor 12a, and the discharging current flows through the resistor 13 via the bypass diode 14, and the ignition device 1 includes a charging current circuit and a discharging current circuit for the capacitor 12b separately.

For example, like a high-frequency multi-ignition signal or a multi-ignition signal, the energization time (high-level period of the ignition signal) in one ignition stroke becomes longer, whereas the cutoff time (low-level period of the ignition signal) In the case of controlling the ignition operation based on the shortened ignition signal, when the time constant of the resistor 12a and the capacitor 12b is “1”, for example, the time constant of the resistor 13 and the capacitor 12b is “0.02 or less. The value of each element is set so that “
In this way, the time constant of the charging circuit and the time constant of the discharging circuit are set to different magnitudes, specifically, the resistance value of the resistor 13 is set to be smaller than the resistor 12a, and the ignition signal is at a low level. The circuit is configured so that the charge can be sufficiently discharged from the capacitor 12b.
In addition, when a normal ignition signal is input, the capacitor 12b continues to accumulate charges by a charging current via the resistor 12a during a period (energization time) when the ignition signal is maintained at a high level. It has a capacity capable of performing (maintaining the charged state).

When the ignition device 1 receives an abnormal ignition signal in which the high level continues for a longer time than the predetermined time, the charge is accumulated in the capacitor 12b of the timer circuit 12 as described above, and the voltage between both ends is set to the voltage Vref. Exceed.
At this time, since a high-level ignition signal is input, the cathode side of the bypass diode 14 is at a higher potential than the anode side, and charge is discharged from the capacitor 12b to the ECU side via the bypass diode 14. (The discharge current does not flow).

  As described so far, regarding the charging / discharging operation of the capacitor 12b provided in the timer circuit 12, when the time constant corresponding to the energization time indicated by the ignition signal and the time constant corresponding to the cutoff time are individually set, for example, In the period A shown in FIG. 2, even when a surge voltage that fluctuates sharply is applied to the ignition signal, the primary current is normally turned on and off without following the surge fluctuation as shown in the period B. Therefore, it is possible to prevent a failure in the switch operation of the switch element 7. In other words, it is possible to closely correspond to the mode of the normal ignition signal, and it is possible to protect the ignition device 1 and the like by detecting an abnormally long energization without being affected by a steep fluctuation.

(Example 2)
FIG. 4 is a circuit diagram illustrating a schematic configuration of an internal combustion engine ignition device according to a second embodiment. Here, the same reference numerals are used for the same or corresponding parts as in the ignition device 1 described in the first embodiment. In addition, redundant description of portions connected and configured in the same manner as the ignition signal 1 is omitted.
The ignition device 2 is configured by connecting a battery 5, an ignition coil 6, a switch element 7, and a spark plug 8 in the same manner as the ignition device 1. Note that one end of a resistor 26 is connected to the control terminal (gate terminal) of the switch element 7. The other end of the resistor 26 is connected to one end of the resistor 27, the cathode of the diode 25b, and one end of the capacitor 25e. The other end of the resistor 27 and the other end of the capacitor 25e are grounded.

  The timer circuit 22 includes a resistor 12a (charging resistor) and a capacitor 12b (not shown) connected in series like the timer circuit 12 shown in FIG. 1, and a connection point between the resistor 12a and the capacitor 12b is provided at the connection point. The anode of the bypass diode 24 and the control terminal (base terminal) of the transistor 25d are connected. The input end of the timer circuit 22, that is, one end of the resistor 12a is connected so as to input an ignition signal from an externally connected ECU or the like. One end of a resistor 23 (discharge resistor) is connected to the input end of the timer circuit 22, and the other end of the resistor 23 is connected to the cathode of the bypass diode 24, the anode of the diode 25b, and one end of the resistor 25c. ing.

The other end of the resistor 25c is connected to the collector of the transistor 25d. The transistor 25d is, for example, an NPN bipolar transistor, and is grounded at the emitter.
Further, the cathode of the diode 25a is connected to the cathode of the bypass diode 24 rather than the connection point between the anode of the diode 25b and the resistor 25c, and the resistors 27 and 26 are connected more than the connection point between the cathode of the diode 25b and the capacitor 25e. The anode of the diode 25a is connected to the connection point.

Next, the operation will be described.
When a normal ignition signal such as a normal ignition signal, a high-frequency multi-ignition signal, or a multi-ignition signal is input, the ignition device 2 has a timer in a period (energization time) in which the ignition signal is at a high level. A charging current flows through the capacitor 12b via the resistor 12a of the circuit 22, and charges are accumulated in the capacitor 12b.
During the period in which the capacitor 12b is in a charged state, no current is output from the connection point between the resistor 12a and the capacitor 12b, so that no current flows through the base of the transistor 25d. Therefore, the transistor 25d is kept off.
At this time, the ignition signal input from the outside is input to the control terminal (gate terminal) of the switch element 7 via the resistor 23, the diode 25b, and the resistor 26, and the switch element 7 is turned on according to the ignition signal. And repeat off state.

When the ignition signal from an externally connected ECU or the like becomes a high level, the switch element 7 is turned on, and a primary current flows through the primary coil 61 as described in the first embodiment while maintaining this level.
Next, when the ignition signal transitions to a low level, a discharge current flows from the capacitor 12b that has accumulated electric charge. This discharge current flows through the diode 24 in the forward direction, and further flows through the resistor 23 to the low potential ECU side and is absorbed by the ground potential portion of the ECU or the like.
At this time, the control terminal of the switch element 7 also transitions to a low potential, and the switch element 7 transitions to an off state to cut off the primary current.
When the primary current is interrupted, a high voltage is generated in the secondary coil 62 and a discharge spark is generated in the spark plug 8.

Thus, when a normal ignition signal is input from the outside, a charging current flows through the resistor 12a to the capacitor 12b of the timer circuit 22 during a period when the ignition signal is at a high level. Transitions to the low level, electric charge is discharged from the capacitor 12b during the low level period, and a discharge current flows through the diode 24 and the resistor 23.
The ignition device 2 operates as described above when a normal ignition signal is input. Similar to the one described in the first embodiment, the time constant of the resistor 12a and the capacitor 12b, the resistor 23, and the capacitor The time constant with respect to 12b is determined to be a different value, and the circuit is configured so as to be able to identify whether or not it is normal corresponding to a normal ignition signal, a high-frequency multi-ignition signal, a multi-ignition signal, and the like. Specifically, for example, when the time constant of the resistor 12a and the capacitor 12b is “1”, the value of each element is set so that the time constant of the resistor 23 and the capacitor 12b is “0.02 or less”. Set.

Further, when an abnormal ignition signal in which the high level continues longer than a predetermined time is input, the ignition device 2 accumulates an electric charge of an arbitrary amount or more in the capacitor 12b of the timer circuit 22, and the capacitor 12b and the bypass diode The connection point of the anode 24 becomes a high potential (the voltage across the capacitor 12b is higher than a predetermined value).
At this time, the cathode side of the bypass diode 24 is at a high potential because a high level ignition signal is input, and the bypass diode 24 is in a state in which no current flows in the forward direction. That is, no charge is discharged from the capacitor 12b to the ECU side via the bypass diode 24 (no discharge current flows).

At this time, since the connection point between the capacitor 12b storing the charge and the bypass diode 24 is at a high potential, a base current flows from the connection point, that is, the output terminal of the timer circuit 22 to the transistor 25d. The transistor 25d is turned on.
Therefore, the high-level ignition signal input to the ignition device 2 is absorbed to the ground side via the resistor 25c and the transistor 25d, and the gate voltage of the switch element 7 decreases. At this time, the gate voltage is gently lowered by the capacitor 25e, the diodes 25a and 25b, the resistor 27, and the like, and the primary current flowing through the switch element 7 is gently reduced. That is, at this time, no high voltage is generated in the secondary coil 62.

(Example 3)
FIG. 5 is a circuit diagram illustrating a schematic configuration of an internal combustion engine ignition device according to a third embodiment. Here, the same reference numerals are used for the same or corresponding parts as in the ignition device 1 described in the first embodiment. In addition, redundant description of parts connected in the same manner as the ignition device 1 and the like is omitted.
The ignition device 3 is configured by connecting a battery 5, an ignition coil 6, a switch element 7, and a spark plug 8 in the same manner as the ignition device 1. Note that one end of a resistor 36 and one end of a resistor 37 are connected to the control terminal (gate terminal) of the switch element 7. The other end of the resistor 36 is connected to the output end of the self-shutoff circuit 35. The other end of the resistor 37 is grounded.
The constant voltage circuit 35 outputs a predetermined voltage using the power of the battery 5 and generates, for example, a DC voltage similar to the constant voltage circuit 11 described in the first embodiment.

The timer circuit 32 is configured to repeat charging and discharging according to the level transition of an ignition signal from an ECU or the like externally connected to the ignition device 3, for example, and is similar to the timer circuit 12 described in the first embodiment. The resistor 12a and the capacitor 12b are connected in series (not shown). The output terminal of the timer circuit 32 (the connection point between the resistor 12a and the capacitor 12b) is connected to the anode of the bypass diode 34 and the input terminal of the self-shutoff circuit 35 (the base of the transistor 351 via the resistor).
The input terminal of the ignition device 3 to which an ignition signal is input from the outside is a connection point between the input terminal of the timer circuit 32 (one end of the resistor 12a) and one end of the resistor 33. The other end of the resistor 33 is the cathode of the bypass diode 34. And connected to the positive input terminal of the comparator 43.

One end of a resistor 41 and a resistor 42 is connected to the inverting input terminal of the comparator 43, and the circuit is configured so that a voltage Vref adjusted by these resistors is input. The other end of the resistor 41 is connected so that the output voltage of the constant voltage circuit 31 is supplied, and the other end of the resistor 42 is grounded.
A self-shutoff circuit 35 is connected to the output terminal of the comparator 43. In the circuit illustrated in FIG. 5, the output terminal of the comparator 43 is connected to the other end of the resistor 36, and the self-shutoff circuit is connected to this connection point. Circuit 35 is configured to apply a pull-up voltage.

The self shut-off circuit 35 includes a transistor 351, a capacitor, and a plurality of resistors. The transistor 351 is, for example, a PNP bipolar transistor, and the output voltage of the constant voltage circuit 31 is supplied to the emitter, and the collector is connected to the connection point between the output terminal of the comparator 43 and the resistor 36 via a resistor or the like.
The base of the transistor 351 is connected to the output terminal of the timer circuit 32 (a connection point between the resistor 12a and the capacitor 12b) via a resistor, and is connected to the circuit so that a base current flows according to the output signal of the timer circuit 32. Yes.

Next, the operation will be described.
When a normal ignition signal such as a normal ignition signal, a high-frequency multi-ignition signal, or a multi-ignition signal is input, the ignition device 3 has a high level period (energization) of the ignition signal as in the ignition device 1 described above. Time), a charging current flows through the capacitor 12b via the resistor 12a (charging resistor) of the timer circuit 32, and charges are accumulated in the capacitor 12b.
Further, during the low level period (interruption time) of the ignition signal, a discharge current flows from the capacitor 12b via the bypass diode 34 and the resistor 33 (discharge resistor), and the charge accumulated in the capacitor 12b is released.

Here, a predetermined bias voltage is applied to the transistor 351 of the self-shutoff circuit 35 by a plurality of resistors connected to the base.
As described above, charging and discharging of the capacitor 12b are repeated in accordance with the signal level of the ignition signal, and the voltage at both ends of the capacitor 12b, that is, the voltage at the output end of the timer circuit 32 is the transistor when the charging and discharging are repeated. When the voltage is lower than the base voltage of 351, the base current of the transistor 351 flows.
Since the output voltage of the constant voltage circuit 31 is supplied to the emitter of the transistor 351 through which the base current flows, a pull-up voltage is applied to the output terminal of the comparator 43 via a resistor connected to the collector.
In other words, a pull-up voltage is applied to the output terminal of the comparator 43 unless a predetermined amount or more of charge is accumulated in the capacitor 12b.

As described above, the voltage Vref is input to the inverting input terminal of the comparator, and an ignition signal is input to the positive input terminal via the resistor 33 from the outside (ECU or the like).
The comparator 43 outputs an output signal of a predetermined voltage indicating significance (energization time) when the ignition signal input through the resistor 33 becomes high level and exceeds the voltage Vref. In other words, the level-converted ignition signal is output.
The ignition signal output from the comparator 43 is input to the control terminal (gate terminal) of the switch element 7 via the resistor 36. The output terminal of the self-shutoff circuit 35 is connected to the connection point between the output terminal of the comparator 43 and the resistor 36. By supplying the pull-up voltage from the output terminal, the ignition signal output from the comparator 43 becomes a signal level that can drive the switch operation of the switch element 7 and is input to the switch element 7. . The switch element 7 to which the ignition signal is input repeats the on state and the off state in the same manner as described in the first embodiment, and energizes and interrupts the primary current to generate a high voltage in the ignition coil 6.

When an abnormal ignition signal that continues the high level indicating the energization time for a predetermined time or more is input from the outside, the charge accumulated in the capacitor 12b increases to a predetermined amount or more, and the potential of the output terminal of the timer circuit 32 ( The voltage across the capacitor 12b) increases.
At this time, since the ignition signal input to the resistor 33 is at a high level, the charge accumulated in the capacitor 12b is not absorbed by any of the ground parts, that is, the discharge current does not flow through the resistor 33 and the capacitor 12b. The voltage at both ends increases. Since the discharge current does not flow from the capacitor 12b, the potential of the output terminal of the timer circuit 32 becomes higher, exceeds the bias voltage supplied to the base of the transistor 351, and the base current of the transistor 351 does not flow.

When the base current of the transistor 351 stops flowing as described above, the self-shutoff circuit 35 stops outputting the pull-up voltage, and the ignition signal input to the control terminal of the switch element 7 can drive the switch element 7. Will be less than the correct level.
When the supply of the pull-up voltage is stopped, the voltage input to the control terminal of the switch element 7 is lowered and the switch element 7 is turned off so that the primary current does not flow through the primary coil 61. The current path is interrupted. When the primary current is cut off, the switching element 7 is gradually changed from the conductive state to the cut-off state so that a high voltage is not generated in the secondary coil 62 so that the primary current is not sharply reduced.

The ignition device 3 is configured to detect abnormality of the ignition signal by repeating charging and discharging of the capacitor 12b provided in the timer circuit 32 in accordance with the voltage level of the ignition signal.
Similarly to the ignition device 1 and the ignition device 2 described above, a charging circuit and a discharging circuit for the capacitor 12b are separately provided, and the time constant of the charging circuit and the time constant of the discharging circuit are set to different values.
In the ignition device 3, specifically, for example, when the time constant between the resistor 12 a and the capacitor 12 b is “1”, the time constant between the resistor 33 and the capacitor 12 b is “0.02 or less”. Thus, the value of each element is set.
In this way, by setting the time constant of the charging circuit and the time constant of the discharging circuit, a normal ignition signal, and a high-frequency multi-ignition signal and a large number of energization times that are longer than the normal ignition signal in one ignition stroke. As for the heavy ignition signal, a normal ignition signal and an abnormal ignition signal (those whose energization time is longer than a predetermined time) can be distinguished.

1, 2, 3 ignition device 5 battery 6 ignition coil 7 switch element 8 spark plug 11, 31 constant voltage circuit 12, 22, 32 timer circuit 12a, 13, 16, 17 resistance 12b capacitor 14, 24, 34 bypass diode 15, 35 self-shutoff circuit 15a, 15b resistor 23, 25c, 26, 27 resistor 25a, 25b diode 25d transistor 25e capacitor 33, 36, 37, 41, 42 resistor 43 comparator 61 primary coil 62 secondary coil 151, 152 comparator 153,351 transistor

Claims (4)

An ignition coil that generates a secondary voltage in the secondary coil when the primary current flowing through the primary coil is interrupted;
In response to an ignition signal from an externally connected control means, a switch unit for generating the secondary voltage by energizing and interrupting the primary current flowing from the power source to the primary side coil;
An energization detector for detecting the length of energization time indicated by the ignition signal;
An energization stop unit that controls the switch unit according to an output voltage of the energization detection unit and stops energization of the primary current;
With
The energization detection unit is
A charging circuit that accumulates electric charge during the energization time indicated by the ignition signal; and a discharge circuit that releases the accumulated electric charge during a cutoff time indicated by the ignition signal;
The discharging circuit has a time constant at the time of discharging smaller than a time constant at the time of charging that the charging circuit has,
Operating the energization stop when the accumulated charge exceeds a predetermined amount;
An internal combustion engine ignition device. The charging circuit is
A capacitor for storing the charge, and a charging resistor connected in series to the capacitor,
The discharge circuit is:
A bypass diode having an anode connected to a connection point between the charging resistor and the capacitor, and a discharge resistor connected to a cathode of the bypass diode;
The energization detection unit is
Depending on the level of the ignition signal, a charging current is passed through the capacitor via the charging resistor, and a discharging current is passed from the capacitor via the bypass diode and the discharging resistor,
The energization stop unit is
Stopping the energization of the primary current when the output voltage of the energization detection unit generated at the connection point between the capacitor and the charging resistor becomes a predetermined value or more;
The ignition device for an internal combustion engine according to claim 1. The charging circuit is
When the ignition signal is at a high level indicating the energization time, the charging current is passed through the capacitor,
The discharge circuit is:
When the ignition signal is at a low level indicating the shut-off time, the discharge current is caused to flow through the discharge resistor to the control means or a portion of the ground potential of the internal combustion engine.
The ignition device for an internal combustion engine according to claim 2. When the time constant during charging of the capacitor and the charging resistor is 1, the charging resistor, the discharging resistor, and the discharging resistor are set so that the time constant during discharging of the capacitor and the discharging resistor is 0.02 or less. Set the capacitor value,
The internal combustion engine ignition device according to any one of claims 1 to 3, wherein the ignition device is an internal combustion engine ignition device.

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