JPH05172029A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable multipoint ignition to be applied without use of a large size capacitor and a special ignition coil by generating an ignition signal, when an ignition control signal having the predetermined pulse width is generated, and the terminal voltage of a capacitor for accumulating ignition energy becomes equal to or above a set value. CONSTITUTION:An ignition device is provided with an ignition circuit 1 having an ignition coil 1G, a capacitor C1 for accumulating ignition energy, a discharge thyrister S1 or the like. Also, the device has a converter 2 for stepping up the output voltage of a DC power supply 2A. Furthermore, the device has an ignition control circuit 3 for applying an ignition signal to the thyrister S1. In this constitution, an ignition control signal having the predetermined pulse width is generated by the control signal generation circuit 3B of the ignition control circuit 3, according to ignition timing, and an ignition signal is generated by a multi-discharge control circuit 3C of the circuit 3, when the terminal voltage of the capacitor C1 is equal to or above a set value. On the other hand, the operation interruption circuit 2D of the converter 2 stops the operation of the device, when voltage across the gate cathodes of the thyrister S1 is equal to or above a reference value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor discharge type ignition device for an internal combustion engine.

[0002]

2. Description of the Related Art As a capacitor discharge type ignition device, an ignition energy storage capacitor is charged by the output of a converter that boosts the voltage of a battery by interrupting a current flowing from a battery to a primary coil of a step-up transformer at a predetermined frequency. Then, a high voltage for ignition is generated by discharging the charge of the capacitor to the primary coil of the ignition coil through a discharging thyristor.

In order to stably perform combustion in the internal combustion engine, it is preferable to extend the duration of ignition spark.
In the capacitor discharge type ignition device, the duration of spark tends to be shorter than that in the current interruption type ignition device. Therefore, by devising the winding specification and magnetic path of the ignition coil, the spark duration can be lengthened, or the spark energy duration capacitor can be increased by increasing the charging voltage to increase the spark duration. There is a proposal to lengthen it.

Further, as seen in Japanese Patent Publication No. 45-26526, a capacitor for ignition energy storage is charged with a voltage boosted by a converter, and a gate signal is applied from a multiple gate signal circuit to a discharging thyristor multiple times to drive the capacitor. There is also one in which a plurality of sparks are generated by causing a plurality of discharges to cause multiple ignition.

[0005]

In an ignition device in which the duration of sparks is lengthened by devising the winding specifications and magnetic path of the ignition coil, the ignition coil becomes large and expensive. Inevitably, when the capacity of the ignition energy storage capacitor is increased to increase its charging voltage, it is inevitable that the power supply circuit for charging the capacitor becomes large.

Further, the conventional ignition device in which the capacitor is discharged a plurality of times to generate a plurality of sparks is not practical because it is necessary to use a large number of expensive step-up transformers for the converter. Also, in this ignition device, in order not to fail commutation of the discharge thyristor,
Since the oscillating frequency of the converter cannot be increased so much, the conversion efficiency of the transformer of the converter cannot be increased.

An object of the present invention is to provide a capacitor discharge type ignition device for an internal combustion engine, which can perform multiple ignition without using a large capacity capacitor.

Another object of the present invention is to increase the conversion frequency in the transformer of the converter by increasing the oscillation frequency of the converter, and to perform multiple ignition without causing the commutation failure of the discharge thyristor. It is an object of the present invention to provide a capacitor discharge type ignition device for an internal combustion engine that can be operated.

[0009]

SUMMARY OF THE INVENTION The present invention comprises a converter for boosting the output voltage of a DC power source such as a battery, an ignition energy storage capacitor charged to one polarity by the output of the converter, and an ignition coil. It conducts when an ignition signal is given, and charges the capacitor to the 1 of the ignition coil.
The present invention relates to an internal combustion engine ignition device including a discharge thyristor provided to cause a secondary coil to discharge, and an ignition control circuit that provides an ignition signal to the discharge thyristor at an ignition timing of the internal combustion engine.

In the present invention, the ignition control circuit is
An ignition control signal generating circuit for generating an ignition control signal having a predetermined pulse width at the ignition timing of the internal combustion engine, the terminal voltage of the ignition energy storage capacitor and the ignition control signal are detected, and the ignition control signal is generated. And a multiple discharge control circuit for generating an ignition signal when the terminal voltage of the capacitor is equal to or higher than a set value. The converter also includes an operation stop circuit that detects the voltage between the gate and cathode of the discharging thyristor and stops the operation when the voltage between the gate and cathode becomes equal to or higher than a reference value.

[0011]

With the above-mentioned structure, since the terminal voltage of the capacitor is already above the set value at the ignition timing of the internal combustion engine, at the same time when the ignition control signal is generated, the ignition signal is generated and the discharge thyristor becomes conductive. To do. Due to the conduction of the thyristor, the electric charge of the capacitor is discharged to the primary coil of the ignition coil, and the ignition operation is performed. When the capacitor discharges, its terminal voltage becomes zero and the ignition signal disappears. When the thyristor becomes conductive, the voltage between the gate and cathode of the thyristor becomes higher than the reference value, so that the operation of the converter is stopped. Therefore, immediately after the discharge thyristor becomes conductive and the ignition operation is performed, the voltage applied between the anode and the cathode of the thyristor becomes zero and the thyristor is cut off. When the thyristor shuts off, the voltage between its gate and cathode becomes lower than the reference value, so that the converter resumes operation and the capacitor is charged. When the terminal voltage of the capacitor reaches the set value while the ignition control signal is generated, the ignition signal is generated and the thyristor is re-conducted.
The ignition operation is performed again. Hereinafter, the same operation is repeated as long as the ignition control signal is generated.

Therefore, by appropriately setting the signal width of the ignition control signal, the ignition operation can be continuously performed a plurality of times, and a large capacity capacitor or a special ignition coil is used. It is possible to make multiple ignitions without.

Further, since the operation of the capacitor is stopped by detecting the conduction of the thyristor from the voltage between the gate and cathode of the discharging thyristor, the commutation of the thyristor fails even if the oscillation frequency of the converter is increased. Never. Therefore, the oscillation frequency of the converter can be set sufficiently high, and the conversion efficiency of the transformer of the converter can be increased.

[0014]

FIG. 1 shows an embodiment of the present invention. In FIG. 1, 1 is an ignition circuit, 2 is a converter, and 3 is an ignition control circuit.

The ignition circuit 1 is a well-known capacitor discharge type circuit, and includes an ignition coil IG and an ignition plug P1 attached to a cylinder of the engine and connected to a secondary coil of the ignition coil IG.
And an ignition energy storage capacitor C1 which is provided on the primary side of the ignition coil and charged by the output of the converter 1 through the diode D1, and an electric charge of the capacitor C1 which conducts when an ignition signal is applied to the ignition coil. It comprises a discharge thyristor S1 for discharging the primary coil and a damper diode D2 connected in parallel with the primary coil of the ignition coil.

In this type of ignition circuit, the capacitor C
It is well known that a circuit in which the positions of 1 and thyristor S1 are interchanged may be used.

The converter 2 is a DC power source 2 such as a battery.
A, a booster circuit 2B to which the output of the DC power source is applied via a switch SW1, an oscillator circuit 2C for outputting a pulse signal Vp having a high frequency as shown in FIG. 2H, and an operation stop circuit 2D. It consists of

The booster circuit 2B comprises a transformer TF1 and a transistor T1 in which a collector-emitter circuit is connected in series to the primary coil of the transformer, and a DC power supply 2A is provided.
The primary current supplied from the switch SW1 is turned on and off by the transistor T1 to output a high frequency high voltage.

The operation stop circuit 2D includes resistors R1 and R2.
And a comparator CM1 and an AND circuit AND1. The comparator CM1 divides the output of a DC constant voltage circuit (not shown) by resistors R1 and R2 to obtain a reference voltage Vr, which is a gate-cathode voltage Vg of the thyristor S1 (FIG. 2F).
In comparison with FIG. 2 (G), the thyristor S
When the gate-cathode voltage Vg of 1 is lower than the reference voltage Vr, the output Vq is set to the high level, and when the gate-cathode voltage Vgk of the thyristor S1 becomes the reference voltage Vr or more, the output Vq is set to the zero level.

The output Vp 'of the AND circuit AND1 is supplied to the base of the transistor T1. As shown in FIG. 2 (I), the output Vp 'of the AND circuit AND1 has the same pulse waveform as the oscillation output of the oscillation circuit 2C when the output Vq of the comparator CM1 is at a high level, and the output Vq of the comparator CM1. Becomes zero when becomes zero level.

The ignition control circuit 3 is provided in a signal generator (not shown), and a pulsar coil 3A for generating a signal at a predetermined position in synchronization with the rotation of the engine, for example, a maximum advance position and a minimum advance position. It is composed of an ignition control signal generation circuit 3B which outputs an ignition control signal Vi at an ignition timing at each rotation speed of the internal combustion engine, and an output of the pulser coil 3A, and a multiple discharge control circuit 3C.

As shown in FIG. 2A, the ignition control signal generation circuit 3B outputs a rectangular wave-shaped ignition control signal Vi having a predetermined signal width at the ignition timing Ti. The ignition control signal generation circuit calculates an ignition timing by an analog calculation circuit based on engine rotation angle information and speed information obtained from the output of the pulsar coil 3A, and generates a signal at the calculated ignition timing. It can be configured by an arithmetic circuit and a signal generating circuit (for example, a monostable multivibrator) that generates an ignition control signal of a constant time width when the ignition timing arithmetic circuit generates a signal. Further, by controlling the width of the output signal of the signal generation circuit according to the engine speed, it is possible to control the time width of the ignition control signal Vi to be shortened as the engine speed increases, for example. ..

The multiple discharge control circuit 3C includes resistors R3 to R7, a comparator CM2, a capacitor C2, diodes D3 and D4, an inverter INV1 and an AND circuit A.
It is composed of ND2. The comparator CM2 has a detection voltage Vc '(FIG. 2) obtained by dividing the terminal voltage Vc of the ignition energy storage capacitor C1 by resistors R3 and R4.
B) is compared with a set voltage Vf obtained by dividing the output voltage of the DC constant voltage circuit by resistors R5 and R6, and when the detected voltage Vc 'is equal to or higher than the set voltage Vf (of the capacitor C1). When the output terminal is grounded when the terminal voltage is above the set value and the detected voltage Vc 'becomes lower than the set voltage Vf (when the terminal voltage of the capacitor C1 becomes lower than the set value). The output terminal is not grounded. The capacitor C2 is charged to a constant voltage through the resistor R7 when the output terminal of the comparator CM2 is in the non-grounded state, and through the output stage of the comparator when the output terminal of the comparator CM2 is in the grounded state. To discharge.

The inverter INV1 is a potential of the output terminal of the comparator CM2 (terminal voltage of the capacitor C2, see FIG. 2C).
Va is inverted and given to the AND circuit AND2. The AND circuit AND2 outputs the high level signal Vd (when the output Vb of the inverter INV1 is at a high level (the terminal voltage Vc of the capacitor C1 is equal to or more than the set value) and the ignition control signal Vi is generated. 2E) and the diode D is generated when this high level signal Vd is generated.
An ignition signal is given to the thyristor S1 through 4.

Next, the operation of the above embodiment will be described. When the switch SW1 is turned on, the oscillation circuit 2C starts oscillating and generates a pulse signal as shown in FIG. At the beginning, the thyristor S1 is in the cutoff state, and the gate-cathode voltage Vgk is equal to or lower than the reference voltage Vf, so that the output Vq of the comparator CM1 is at a high level. At this time, the AND circuit AND1 supplies the pulse signal Vp 'as shown in FIG. 2 (I) to the transistor T1 to turn on / off the transistor T1. As a result, the primary current of the transformer TF1 is interrupted, so that a pulsed high voltage is induced in its secondary coil. Since this high voltage is applied to the capacitor C1 through the diode D1, the capacitor C1 is gradually charged, and its terminal voltage gradually increases. The waveform of the terminal voltage of this capacitor C1 is shown in Fig. 2.
It is similar to the waveform of the detection voltage Vc 'shown in FIG. The detection voltage Vc 'of the terminal voltage of the capacitor C1 is the ignition timing Ti.
The set voltage Vf is exceeded at a time earlier than that.

When the detected voltage Vc 'exceeds the set voltage Vf, the output Va of the comparator CM2 becomes low level, and the voltage across the capacitor C2 is maintained at zero. Therefore, the output of the inverter INV1 is at high level.

As shown in FIG. 2A, the ignition control signal generation circuit 3B outputs the ignition control signal Vi at the ignition timing Ti of the internal combustion engine.
When the ignition control signal Vi exceeds the threshold value Vt1 of the AND circuit AND1, the output Vd of the AND circuit AND2 is generated.
(FIG. 2E) goes high, providing an ignition signal to thyristor S1. As a result, the thyristor S1 becomes conductive,
The electric charge of the capacitor C1 is changed to the thyristor S1 and the ignition coil I.
Discharge through the G primary coil. When the capacitor C1 is discharged, a large magnetic flux change occurs in the iron core of the ignition coil, so that the high voltage Vh (Fig.
J) is generated, and a discharge current i1 flows from the secondary coil of the ignition coil through the ignition plug P1 as shown in FIG. 2 (K) to generate a spark in the ignition plug.

When the capacitor C1 is discharged, its terminal voltage becomes zero (the relationship of Vc '<Vf is established).
The output of the comparator CM2 becomes non-grounded and the capacitor C
2 is charged through resistor R7. Therefore capacitor C
The terminal voltage Va of 2 rises as shown in FIG. The terminal voltage of the capacitor C2 is the threshold value Vt2 of the inverter INV1.
While the output Vb of the inverter is zero while the output Vb is zero, the output Vd of the AND circuit AND2 is output while the output Vb is zero even if the ignition control signal Vi of the threshold value Vt1 or more is generated.
Is zero.

When the thyristor S1 becomes conductive, the gate-cathode voltage Vg exceeds the reference value Vr.
The output Vq of the comparator CM1 becomes zero as shown in (G), and the output of the AND circuit AND1 becomes zero as shown in FIG. 2 (I). Therefore, when the thyristor S1 becomes conductive, the transistor T1 is held in the cutoff state, and the converter 2 stops operating. When the converter stops operating, the voltage applied between the anode and cathode of the thyristor S1 becomes zero, and the thyristor S1 surely commutates.

As described above, in the present invention, since the operation of the converter is once stopped when the thyristor S1 is conducted, even if the output frequency of the converter is set high,
The commutation of the thyristor S1 can be reliably performed, and the conversion efficiency of the transformer of the converter can be increased.

When the thyristor S1 is turned off, the gate-cathode voltage Vgk becomes lower than the reference voltage Vr, so that the output Vq of the comparator CM1 becomes high level and the AND circuit AND1 outputs the pulse signal Vp '. As a result, the transistor T1 restarts the on / off operation, and the converter 2 produces an output. Therefore, the charging of the capacitor C1 is restarted.

When the terminal voltage of the capacitor C1 reaches the set value and the detected voltage Vc 'reaches the set voltage Vf, the output terminal of the comparator CM2 is grounded, so that the voltage across the capacitor C2 becomes zero. Become. As a result, the output Vb of the inverter INV1 becomes high level, and if the ignition control signal Vi of the threshold value Vt1 or more is generated at this time, the output Vd of the AND circuit AND2 becomes high level. Therefore, an ignition signal is given to the thyristor S1 and the thyristor S1 is re-conducted. As a result, the capacitor C1 is discharged and the ignition operation is performed again. Thereafter, the same operation as described above is repeated, and the ignition operation is repeated at a predetermined time interval Td1 as shown in FIG. 2K during the period Td2 during which the ignition control signal Vi having the threshold value Vt1 or more is generated. Then, multiple ignition is performed. When the internal combustion engine is ignited multiple times, combustion is performed stably,
Since complete combustion can be performed, exhaust gas can be purified and fuel consumption can be saved.

When the ignition control signal Vi disappears, the AND circuit AN does not operate even if the output of the inverter INV1 becomes high level.
Since the AND condition of D2 is not satisfied, the capacitor C
Even if the terminal voltage of 1 reaches the set value, the output terminal of the comparator CM2 is grounded, and the output of the inverter circuit INV1 becomes high level, the ignition signal is not generated. Therefore, the charging of the capacitor C1 is continued, and its terminal voltage gradually rises to a value higher than the set value.

In the above description, the ignition control signal generating circuit calculates the ignition timing by the analog calculation circuit, but the ignition timing may be calculated by the microcomputer in some cases.

[0035]

As described above, according to the present invention, the ignition control signal is generated by detecting the terminal voltage of the ignition energy storage capacitor and the ignition control signal having a predetermined signal width generated at the ignition timing. In addition, since the ignition signal is generated when the terminal voltage of the capacitor is equal to or higher than the set value, the ignition operation can be continuously performed multiple times by appropriately setting the signal width of the ignition control signal. Therefore, there is an advantage that multiple ignition can be performed without using a large-capacity capacitor or using a special ignition coil.

Further, in the present invention, the operation of the capacitor is stopped by detecting the conduction of the thyristor from the gate-cathode voltage of the discharging thyristor, so that the operation of the capacitor is stopped even if the oscillation frequency of the converter is increased. The commutation never fails. Therefore, there is an advantage that the oscillation frequency of the converter can be set sufficiently high and the conversion efficiency of the transformer of the converter can be increased.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

2 (A) to (K) are waveform charts showing signal waveforms of respective portions in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ignition circuit, IG ... Ignition coil, C1 ... Ignition energy storage capacitor, S1 ... Discharge thyristor, 2 ... Converter, 2A ... DC power supply, 2B ... Booster circuit, TF1 ...
Transformer, T1 ... Transistor, 2C ... Oscillation circuit, 2D
... operation stop circuit, CM1 ... comparator, AND1 ... AND circuit, 3 ... ignition control circuit, 3A ... pulser coil, 3B ... ignition control signal generation circuit, 3C ... multiple discharge control circuit, CM2
… Comparator, INV1… Inverter, AND2… And circuit.

Claims (1)

[Claims] 1. A converter for boosting the output voltage of a DC power source, an ignition energy storage capacitor charged to one polarity by the output of the converter, an ignition coil, and a conduction circuit when an ignition signal is applied. An ignition device for an internal combustion engine including a discharge thyristor provided to discharge the electric charge of the capacitor to a primary coil of an ignition coil, and an ignition control circuit for giving an ignition signal to the discharge thyristor at the ignition timing of the internal combustion engine. In the above, the ignition control circuit detects an ignition control signal generation circuit that generates an ignition control signal having a predetermined pulse width at an ignition timing of the internal combustion engine, a terminal voltage of the ignition energy storage capacitor, and the ignition control signal. Discharge control circuit for generating the ignition signal when the control signal is generated and the terminal voltage of the capacitor is equal to or higher than a set value. Wherein the converter includes an operation stop circuit that detects the voltage between the gate and cathode of the discharge thyristor and stops the operation when the voltage between the gate and cathode becomes a reference value or more. Ignition device for internal combustion engine.