JPH0650106B2 - Ignition device for internal combustion engine with over-rotation prevention function - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an internal combustion engine ignition device having an over-rotation preventing function for preventing the rotational speed of an internal combustion engine from exceeding a set value.

[Prior Art] As an internal combustion engine ignition device having a function of preventing over-rotation of an internal combustion engine, when the rotational speed of the engine exceeds a set value, the ignition operation is stopped to completely extinguish the engine. However, in the case of such a configuration, when the engine speed reaches the set value, the engine suddenly loses fire completely, causing a sudden deceleration of the engine and giving a driver an uncomfortable feeling. there were. Therefore, as shown in Japanese Examined Patent Publication No. 53-13740, when the rotational speed of the engine exceeds a set value, the engine is misfired at every predetermined ignition cycle and the engine is placed once or several times. Ignition devices have been proposed which are designed to be misfired.

[Problems to be Solved by the Invention] The above-mentioned conventional ignition device for an internal combustion engine (Japanese Patent Publication No. 53-1374).
No. 0), the first capacitor is charged with a constant voltage by the output of the generator coil with a constant time constant, and has a capacity sufficiently larger than the first capacitor and the charge of the first capacitor causes a constant time constant. Since the speed detection circuit is composed of the pump-up circuit including the second capacitor to be charged, there is a problem that the time constant of the speed detection circuit is considerably large and the responsiveness to changes in the rotation speed is deteriorated.

It is an object of the present invention to provide an ignition device for an internal combustion engine with an over-rotation preventing function, in which a discharge circuit having a large time constant is eliminated from a circuit for detecting the rotation speed and the responsiveness to changes in the rotation speed is improved.

[Means for Solving the Problems] The present invention, as seen in its embodiment, has an ignition coil 1
And a thyristor S1 that discharges the electric charge of the ignition energy storage capacitor through the primary coil of the ignition coil when it conducts with the ignition energy storage capacitor C1 provided on the primary side of the ignition coil. Ignition operation for preventing the ignition operation of the ignition circuit 3 by short-circuiting or opening the ignition circuit 3 and a part of the circuit on the primary side of the ignition coil to prevent discharge of the ignition energy storage capacitor C1. Blocking switch 4,
An ignition device for an internal combustion engine, comprising: an ignition operation blocking trigger circuit 5 that triggers an ignition operation blocking switch 4 every predetermined ignition cycle when the rotation speed of the internal combustion engine exceeds a set value. It is the one that enhances sex.

In the present invention, the ignition operation blocking trigger circuit 5 includes an integrating circuit 6 that constantly charges the integrating capacitor with a constant time constant to perform an integrating operation, and an integrating circuit reset switch connected in parallel to the integrating capacitor. 7, a reset trigger circuit 8 that detects the primary voltage of the ignition coil and triggers a reset switch when the primary voltage reaches a predetermined threshold level, and an integrated voltage obtained across the integrating capacitor. The trigger signal supply circuit 9 supplies a trigger signal to the ignition operation blocking switch when the integrated voltage becomes lower than the reference voltage as compared with the reference voltage.

[Operation] In the above ignition device, when the engine speed is lower than the set value, the integration voltage cannot be reduced to the reference voltage or less because the interval at which the integration circuit is reset is long.
Therefore, the ignition operation is performed without any trouble. The interval at which the integrator circuit is reset becomes shorter as the rotation speed increases, and when the rotation speed becomes equal to or higher than the set value, the integrated voltage becomes equal to or lower than the reference voltage. When the integrated voltage drops below the reference voltage, the ignition blocking switch is triggered,
The ignition operation is blocked. In the capacitor discharge type ignition circuit, when the ignition operation is blocked, the ignition coil 1
Since the voltage does not appear in the next coil, when the ignition operation is blocked, the integration circuit is not reset and the integration operation continues. Therefore, when a certain period of time elapses after the ignition operation is blocked, the integrated voltage becomes higher than the reference voltage, the trigger of the ignition blocking switch is interrupted, and the ignition operation is restored. If the rotation speed is still equal to or higher than the set value after the ignition operation is restored, the integrated voltage again becomes equal to or lower than the reference voltage, and thus the ignition operation is blocked again.
Since these operations are repeated, the ignition operation is stopped every predetermined ignition cycle, and the engine speed gradually decreases.

As described above, according to the present invention, since the ignition spark is thinned out at every predetermined ignition cycle during the over-rotation preventing operation, when the engine is completely misfired when the rotation speed reaches the set value. It is possible to prevent the driver from feeling uncomfortable by gently decelerating the engine as compared with.

Further, in the present invention, since the integrating circuit is reset every time the ignition operation is performed, it is not necessary to provide the integrating circuit with a discharging circuit having a large time constant. Therefore, the responsiveness to the fluctuation of the rotation speed can be enhanced, and the over-rotation preventing operation can always be performed appropriately.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the overall construction of an embodiment of the present invention.
In the figure, 1 is a known ignition coil in which a primary coil and a secondary coil are wound around an iron core, and 2 is an ignition coil 1.
This is a primary current control circuit that generates a high voltage in the secondary coil of the ignition coil 1 by controlling the secondary current, and the ignition coil 1 and the primary current control circuit 2 constitute an ignition circuit 3. An ignition plug P attached to a cylinder of the engine is connected to the secondary coil of the ignition coil 1.
When a high voltage is generated in the secondary coil, a spark is generated in the spark plug P and the engine is ignited. In the present invention, as the primary current control circuit 2, an ignition energy storage capacitor provided on the primary side of the ignition coil and a thyristor that discharges the electric charge of the capacitor to the primary coil of the ignition coil when conducting is established. A capacitor discharge type circuit is used.

Reference numeral 4 denotes an ignition operation blocking switch, which is provided so as to block the ignition operation by short-circuiting a part of the primary current control circuit 2 when conducting.

Reference numeral 5 is an ignition operation blocking trigger circuit that triggers the ignition operation blocking switch 4 when the engine speed reaches a set value. This trigger circuit always charges the integration capacitor with a constant time constant to perform an integration operation. The integrating circuit 6 for performing the above operation, the integrating circuit resetting switch 7 connected in parallel to the integrating capacitor in the integrating circuit 6, and the primary voltage of the ignition coil 1 are detected to detect a predetermined threshold voltage. The reset trigger circuit 8 that triggers the reset switch 7 when the level is reached, and the integrated voltage obtained across the integrating capacitor in the integrating circuit 6 are compared with the reference voltage, and when the integrated voltage becomes equal to or lower than the reference voltage. And a trigger signal supply circuit 9 for supplying a trigger signal to the ignition operation blocking switch.

In the above embodiment, the integrating circuit 6 always performs the integrating operation of charging the integrating capacitor with a constant time constant. When the voltage V1 is induced in the primary coil of the ignition coil 1 at the ignition timing of the engine, the reset trigger circuit 8 makes the reset switch 7 conductive, and the reset switch 7 instantly discharges the electric charge of the integration capacitor. Therefore, a triangular waveform integrated voltage Vc that rises at a constant gradient and returns to zero each time the ignition operation is performed is obtained across the integrating capacitor of the integrating circuit 6.

The trigger signal supply circuit 9 compares the integrated voltage Vc with the reference voltage, determines that the engine speed has reached the set value when the integrated voltage Vc becomes equal to or lower than the reference voltage, and causes the ignition operation blocking switch 4 to operate. Supply a trigger signal.

FIG. 2 shows an embodiment embodying the configuration of FIG. 1 described above. In this embodiment, the primary current control circuit 2 includes an ignition energy storage capacitor C1, diodes D1 to D3, a thyristor S1 and , Resistor R1 and signal coil L
It is composed of a known capacitor discharge type circuit composed of s and an exciter coil Le. In this primary current control circuit, the ignition energy storage capacitor C1 is charged to the polarity shown by the positive half cycle output of the exciter coil Le through the diode D1. Signal coil L
Positive and negative half cycle signal voltage generated by s (Fig. 3A)
When a positive half cycle signal voltage is supplied to the gate of the thyristor S1 as the ignition signal Vg (Fig. 3C) at the ignition timing, the thyristor S1 becomes conductive and the charge of the capacitor C1 is transferred to the thyristor S1 and the ignition coil. Discharge through the primary coil of 1.

Therefore, the terminal voltage Vc1 of the capacitor C1 changes as shown in FIG. 3D with respect to the engine rotation angle .theta., And when the capacitor C1 discharges at the ignition timing, the primary coil of the ignition coil 1 becomes as shown in FIG. 3E. A voltage V1 in which the ground side has a positive polarity is induced. This voltage V1 is boosted and the ignition coil 1
A high voltage is induced in the secondary coil, and the high voltage causes a spark in the spark plug P to ignite the engine.

The ignition operation blocking switch 4 includes an NPN transistor Tr1 having an emitter grounded and a collector connected to the gate of the thyristor S1, and a resistor R2 connected in parallel between the base and emitter of the transistor Tr1. When a base current is applied, the transistor becomes conductive and the gate and cathode of the thyristor S1 are short-circuited.

The integrating circuit 6 is composed of a resistor R3 and an integrating capacitor C2 connected to a direct current (not shown) (for example, a battery) through the resistor R3. The integrating capacitor C2 is a constant resistor except when a reset switch described later is turned on. R3
It is designed to be charged with a constant time constant through.

The reset switch 7 comprises an NPN transistor Tr2 whose emitter is grounded and whose collector is connected to the non-grounded side terminal of the capacitor C2. When the transistor Tr2 is turned on, the integrating capacitor C2 is instantaneously discharged through the collector and emitter of the transistor Tr2.

The reset trigger circuit 8 includes an NPN transistor Tr3 having a collector connected to the base of the transistor Tr2 and an emitter grounded, a diode D4 having a cathode connected to the non-grounded side terminal of the primary coil of the ignition coil 1, and a diode D4. A Zener diode Z1 having an anode connected to the anode, a resistor R4 connected between the cathode of the Zener diode Z1 and the base of the transistor Tr3,
Resistors R5 and R6 connected between a DC power source (not shown) and the base and collector of the transistor Tr3, respectively.
And a diode D5 connected between the base and emitter of the transistor Tr3 with the anode facing the ground side.

In the reset trigger circuit 8, the resistor R5 is normally provided.
Since the base current flows through the transistor Tr3 through
The transistor Tr3 is conductive. At this time, the transistor Tr2 is held in the cutoff state, and the integrating circuit 6 performs the integrating operation without any trouble. During the ignition operation, a voltage V1 having a positive polarity on the ground side is induced in the primary coil of the ignition coil 1.
When this voltage V1 reaches a predetermined threshold level, the Zener diode Z1 is turned on and the diode D5 → resistor R4 → Zener diode Z1 → from the primary coil.
A current flows through the path of the diode D4. At this time, a voltage drop across the diode D5 causes a transistor Tr3.
Is reverse-biased, so that the transistor Tr3 is turned off for a short time. When the transistor Tr3 is cut off, a base current flows to the transistor Tr2 through the resistor R6, so that the transistor Tr2 becomes conductive and the electric charge of the capacitor C2 is instantaneously discharged. Therefore, the waveform of the integrated voltage Vc2 obtained across the integrating capacitor C2 is as shown in FIG. 3B.

The trigger signal supply circuit 9 has a negative input terminal connected to the non-grounded terminal of the integrating capacitor C2, and an output terminal connected to the base of the transistor Tr1.
A resistor R7 connected between the positive phase input terminal of M1 and a DC power source (not shown), a resistor R8 connected between the positive phase input terminal of the comparator CM1 and ground, and an output terminal of the comparator CM1 and not shown. It consists of a resistor R9 connected to the DC power supply. The comparator CM1 compares the integrated voltage Vc2 with the reference voltage Vr obtained across the resistor R8. When the integrated voltage Vc2 exceeds the reference voltage Vr, the comparator CM1
The output terminal of is at ground potential, and at this time the transistor Tr1
Is not supplied with base current. On the other hand, when the integrated voltage Vc2 becomes lower than the reference voltage, the output terminal of the comparator CM1 becomes non-grounded, so that the base current is supplied to the transistor Tr1 through the resistor R9 and the transistor Tr1 becomes conductive.

The waveform of the integrated voltage Vc2 shown by the solid line in FIG. 3B shows the waveform when the engine speed is less than the set value. In this case, since the integrated voltage Vc2 exceeds the reference voltage Vr before the signal coil Ls generates the positive half cycle signal voltage, when the signal coil Ls generates the positive half cycle signal, the comparator CM1 outputs The output terminal is already grounded, and the base current is not supplied to the transistor Tr1. Therefore, at this time, the transistor Tr1 is in the cut-off state, the ignition signal is supplied from the signal coil Ls to the thyristor S1 without any trouble, and the ignition operation of the engine is performed without any trouble.

The interval at which the integration circuit is reset is inversely proportional to the engine speed, and the interval at which the integration capacitor is reset becomes shorter as the engine speed increases (the integration capacitor charging time becomes shorter. Therefore, the terminal voltage of the integrating capacitor becomes lower as the rotation speed of the engine increases, and when the rotation speed of the engine exceeds the set value, the signal coil as shown by the broken line in FIG. The integrated voltage Vc2 becomes lower than the reference voltage Vr when Ls generates a positive half cycle signal voltage. In this state, when the signal coil Ls generates a positive half cycle signal voltage, the output terminal of the comparator CM1 is not grounded and the base current is supplied to the transistor Tr1. Therefore, the signal coil Ls is supplied. Generates a positive half cycle signal voltage and at the same time the transistor Tr1 becomes conductive and prevents the firing signal Vg from being supplied to the thyristor S1. As described above, when the engine speed becomes equal to or higher than the set value, the ignition operation preventing switch 4 is turned on to prevent the ignition signal from being supplied from the signal coil Ls to the thyristor S1.
The ignition operation will not be performed. At the ignition timing when the ignition operation is blocked, the voltage V1 is applied to the primary coil of the ignition coil 1.
Is not induced, the reset trigger circuit 8 does not trigger the reset switch 7. At this time, the integration capacitor C
2 continues to be charged, and the integrated voltage V
c2 is higher than the reference voltage. Therefore, at the next ignition timing, the transistor Tr1 does not conduct, and the ignition operation is performed without any trouble. When the ignition operation is performed in this way, the integrating circuit is reset again. When the rotation speed of the engine is high and the integrated voltage Vc2 becomes equal to or lower than the reference voltage Vr at the later ignition timing, the transistor Tr1 is turned on again to prevent the ignition operation of the engine. In this way, in the rotation region equal to or higher than the set rotation speed, the ignition operation is blocked every predetermined ignition cycle, the ignition spark of the engine is thinned, and the rotation speed of the engine is reduced.

In the device of the present invention, since the integration constant is constant, the number of times ignition sparks are thinned increases as the engine speed increases. Therefore, it is possible to appropriately and smoothly suppress the increase in the rotation speed, and to always perform the stable over-rotation preventing operation without changing the rotation speed up and down during the over-rotation control. Moreover, since the ignition coil generates the primary voltage and the next primary voltage is generated, integration is performed to determine the engine speed for each ignition cycle.
It is possible to perform control with good responsiveness.

In the embodiment shown in FIG. 2, the ignition operation preventing switch 4 is used.
Thus, the gate and cathode of the thyristor S1 are short-circuited, but the switch 4 may short-circuit the signal coil Ls. Also, as shown in FIG.
The exciter coil Le is activated by the ignition operation preventing switch 4.
Can also be configured to be short-circuited. In the embodiment shown in FIG. 4, the ignition operation preventing switch 4 comprises a thyristor S2, and a resistor R2 is connected between the gate and cathode of the thyristor S2. The thyristor S2 conducts when the output terminal of the comparator CM1 is not grounded and the exciter coil Le generates an output voltage of a positive half cycle to short-circuit the exciter coil, thereby charging the capacitor C1. To prevent the ignition operation. The other points are similar to those of the embodiment shown in FIG. The waveform of each part of the embodiment of FIG. 4 is shown in FIG. 5, and the waveform of the voltage V2 across the thyristor S1 is shown in FIG. 5C.

In the embodiment shown in FIG. 4, the thyristor S2 can be connected between the cathode of the diode D1 and the ground, and the thyristor S1 can also serve as a switch for preventing the ignition operation. When the thyristor S1 also serves as the ignition operation preventing switch, the output terminal of the comparator CM1 may be connected to the gate of the thyristor S1.

FIG. 6 shows the output of the negative half cycle of the exciter coil Le without the special provision of the signal coil, and the thyristor S1.
This embodiment shows an embodiment using the primary current control circuit 2 adapted to give an ignition signal to the. In this embodiment, the non-ground side terminal and the ground side terminal of the exciter coil Le have their anodes grounded, respectively. Connected to the cathodes of the diodes D6 and D7, and connected to the gate of the thyristor S1 is the collector of the transistor Tr1 which constitutes the ignition operation blocking switch.

In the embodiment of FIG. 6, the positive half cycle output of the exciter coil Le charges the capacitor C1 through the diode D1 and the negative half cycle output of the exciter coil Le sends a firing signal to the thyristor S1 through the diode D3. Given. The transistor Tr1 constituting the ignition operation blocking switch 4 bypasses the ignition operation by bypassing the ignition signal given from the exciter coil Le through the diode D3 from the thyristor S1 when it is turned on.
The other points are similar to those of the embodiment shown in FIG.

In the above embodiment, the comparator CM1 and the resistors R7 and R8 form a trigger signal supply circuit. The trigger signal supply circuit compares the integrated voltage with the reference voltage and the integrated voltage becomes equal to or lower than the reference voltage. The circuit is not limited to the above-mentioned configuration as long as it is a circuit that supplies a trigger signal to the ignition operation blocking switch 4 during the operation. For example, as shown in FIG. 7, an NPN transistor Tr4 whose emitter is grounded and whose collector is connected to a DC power source through a resistor R9.
, A resistor R10 connected between the base and emitter of the transistor Tr4, and a Zener diode Z2 whose anode is connected to the base of the transistor Tr4. When the trigger signal supply circuit 9 shown in FIG. 7 is used, the collector of the transistor Tr4 is connected to the base of the transistor Tr1 of the ignition operation blocking switch (or the gate of the thyristor S2) and the cathode of the Zener diode Z2 is integrated. Connect to the non-grounded terminal of capacitor C2.

In the circuit of FIG. 7, the Zener voltage of the Zener diode Z2 is the reference voltage Vr, and when the integrated voltage Vc2 exceeds the reference voltage Vr, the transistor Tr4 becomes conductive and the integrated voltage Vc2 becomes equal to or lower than the reference voltage Vr. When this happens, the transistor Tr4 is cut off. When the transistor Tr4 is conducting, the trigger signal input terminal of the ignition operation blocking switch 4 is kept at the ground potential, so that the ignition operation blocking switch 4 is not triggered. On the other hand, when the transistor Tr4 is turned off, the trigger signal is supplied to the ignition operation blocking switch 4 through the resistor R9, and the switch 4 is turned off.
Is conducted and the ignition operation is blocked.

In each of the above-described embodiments, a switch means is inserted between the resistor R9 of the trigger signal supply circuit 9 and the DC power supply (not shown) to close the predetermined condition. If the trigger signal is supplied to the ignition operation preventing switch 4 only when the integrated voltage Vc2 becomes equal to or lower than the reference voltage Vr in the state where the predetermined condition is satisfied, the over-rotation preventing operation is performed. Can be done. For example, the rotational speed of the engine can be limited only when an abnormality occurs in the hydraulic pressure of the internal combustion engine, the temperature of the cooling water, or the like.

In the above description, when the ignition operation blocking switch is triggered to conduct and short-circuit a part of the primary current control circuit, a switch that opens when triggered is used as an ignition operation blocking switch. The ignition operation blocking switch may be inserted into a part of the primary current control circuit to open (separate) a part of the primary current control circuit to block the ignition operation.

[Effects of the Invention] As described above, according to the present invention, the integrating circuit is reset by detecting the voltage appearing in the primary coil of the ignition coil during the ignition operation and triggering the reset switch. Since the ignition operation blocking switch is triggered when the integrated voltage becomes equal to or lower than the reference voltage, the ignition operation is stopped every predetermined ignition cycle when the engine speed becomes equal to or higher than the set value, and the engine is stopped. It is possible to prevent the rotation speed of the vehicle from gradually decreasing and prevent the rotation speed from rapidly decreasing during the over-rotation preventing operation to give the driver uncomfortable feeling.

Further, according to the present invention, since the integrating circuit is reset every time the ignition operation is performed, it is not necessary to provide the integrating circuit with a discharging circuit having a large time constant. Therefore, the responsiveness to the fluctuation of the rotation speed can be enhanced, and the over-rotation preventing operation can always be performed appropriately.

Further, according to the present invention, since the number of sparks thinned out increases as the rotation speed increases, it is possible to accurately and smoothly suppress the increase in the rotation speed, and to increase or decrease the rotation speed during the over-rotation preventing operation. There is an advantage that it is possible to always perform a stable over-rotation preventing operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall structure of an embodiment of the present invention, FIG. 2 is a circuit diagram showing an embodiment embodying the structure of FIG. 1, and FIG. Diagram showing operation waveforms, FIG. 4 is a circuit diagram showing another embodiment of the present invention, FIG.
FIG. 7 is a diagram showing operation waveforms of respective parts of the embodiment shown in FIG. 4, FIG. 6 is a circuit diagram showing still another embodiment of the present invention, and FIG. 7 is a trigger signal which can be used in the present invention. It is a circuit diagram showing a modification of a supply circuit. 1 ... Ignition coil, 2 ... Primary current control circuit, 3 ... Ignition circuit, 4 ... Ignition operation blocking switch, 5 ... Ignition operation blocking trigger circuit, 6 ... Integration circuit, 7 ... Reset Switch, 8 ... Reset trigger circuit, 9 ... Trigger signal supply circuit, C1 ... Ignition energy storage capacitor, S1 ... Thyristor.

Claims (1)

[Claims] 1. An ignition coil and a thyristor for discharging the electric charge of the ignition energy storage capacitor through the primary coil of the ignition coil when the ignition coil is electrically connected to the ignition energy storage capacitor provided on the primary side of the ignition coil. The ignition circuit of the capacitor discharge type has an ignition operation of the ignition circuit by short-circuiting or opening a part of the circuit on the primary side of the ignition coil to prevent discharge of the ignition energy storage capacitor when triggered. An ignition device for an internal combustion engine, comprising: an ignition operation blocking switch for blocking; and an ignition operation blocking trigger circuit for triggering the ignition operation blocking switch when the rotation speed of the internal combustion engine exceeds a set value. The operation prevention trigger circuit includes an integration circuit that always charges an integration capacitor with a constant time constant to perform integration operation, and the integration capacitor. And an integrator circuit reset switch connected in parallel to the sensor, and a reset for detecting the primary voltage of the ignition coil and triggering the reset switch when the primary voltage reaches a predetermined threshold level. And a trigger signal supply circuit that compares the integrated voltage obtained across the integration capacitor with a reference voltage and supplies a trigger signal to the ignition operation blocking switch when the integrated voltage becomes equal to or lower than the reference voltage. An ignition device for an internal combustion engine, which is provided with an over-rotation preventing function.