JP3584664B2 - Capacitor discharge type internal combustion engine ignition device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
[0002]
The present invention relates to a capacitor discharge type ignition device for an internal combustion engine.
[Prior art]
A capacitor discharge type ignition device for an internal combustion engine includes an ignition coil in which an ignition plug attached to a cylinder of the internal combustion engine is connected to a secondary side, a capacitor charging power supply for generating a capacitor charging voltage, and an ignition coil. An ignition capacitor, which is provided on the primary side and is charged to one polarity by the output of the capacitor charging power supply unit, and conducts when a trigger signal is given, and charges the electric charge accumulated in the ignition capacitor with the ignition coil. A discharge switch for discharging through the primary coil, and an ignition timing control unit for giving a trigger signal to the discharge switch at the ignition timing of the internal combustion engine.
[0003]
FIG. 10 shows an example of the configuration of one cylinder of this type of conventional ignition device. In FIG. 10, reference numeral 1 denotes an ignition coil having a primary coil 1a and a secondary coil 1b, and 2 denotes output terminals 2a and 2b. A power supply unit 3 for charging a capacitor having one output terminal 2a grounded and an ignition timing control unit 3 for outputting a trigger signal Vt at the ignition timing of the internal combustion engine.
[0004]
The ignition coil 1 is provided with one end of a primary coil 1a and one end of a secondary coil 1b grounded. One end of an ignition capacitor C1 is connected to a non-grounded terminal of the primary coil 1a. The other end of the capacitor C1 is connected to the non-ground side output terminal 2b of the capacitor charging power supply unit 2 through a diode D1 whose cathode is directed toward the capacitor C1. Th1 is a thyristor connected between the other end of the ignition capacitor C1 and ground with the cathode directed to the ground, and the gate of this thyristor is connected to the output terminal of the ignition timing control unit 3. A discharge switch is constituted by the thyristor Th1.
[0005]
D2 is a flywheel diode connected to both ends of the primary coil 1a of the ignition coil 1 with its cathode facing the ground, P is a spark plug attached to a cylinder of the internal combustion engine, and a non-ground terminal of the spark plug P Is connected to a non-ground side terminal of the secondary coil 1b of the ignition coil 1 through a high voltage cord.
[0006]
The capacitor charging power supply unit 2 generates a voltage for charging the ignition capacitor 3 to a relatively high voltage of about 200 to 250 [V]. The power supply unit 2 is driven by an internal combustion engine. An exciter coil provided in a magnet generator, a generator coil provided in a magnet generator driven by an internal combustion engine, and a chopper circuit for increasing the output of the generator coil, or a battery and an output voltage of the battery For example, a DC-DC converter that boosts (for example, 12 [V]) to about 200 to 250 [V] is used.
[0007]
The ignition capacitor C1 is charged to the illustrated polarity through the diode D1, the primary coil 1a of the ignition coil 1 and the flywheel diode D2 by the output of the capacitor charging power supply unit 2.
[0008]
The ignition timing control section 3 supplies a trigger signal Vt to the gate of the thyristor Th1 when the ignition timing of the internal combustion engine is detected. As a result, the thyristor Th1 becomes conductive, so that the electric charge accumulated in the ignition capacitor C1 is discharged through the thyristor Th1 and the primary coil 1a of the ignition coil 1. This discharge causes a large change in magnetic flux in the core of the ignition coil, and a high voltage for ignition is induced in the secondary coil 1b. Since the high voltage induced in the secondary coil of the ignition coil is applied to the ignition plug P, a spark discharge occurs in the ignition plug and the engine is ignited.
[0009]
FIG. 10 shows the configuration of one cylinder of the ignition device. However, when the internal combustion engine has two or more cylinders, the portion excluding the capacitor charging power supply unit 2 and the ignition timing control unit 3 is omitted. The ignition capacitors C1 provided for each cylinder are charged by the capacitor charging power supply unit 2 for each cylinder. In this case, when the ignition timing of each cylinder is detected, the ignition timing control unit 2 gives a trigger signal Vt to the thyristor Th1 constituting the discharge switch for each cylinder.
[0010]
[Problems to be solved by the invention]
In recent years, along with the tightening of exhaust gas regulations for internal combustion engines, in order to purify the exhaust gas even more, it has been practiced to dilute the fuel (air-fuel mixture) and burn it. Therefore, there is a need for an ignition device for an internal combustion engine that is capable of generating a spark discharge that has a fast rise time, does not break a spark, and has a long duration.
[0011]
The capacitor discharge type ignition device is characterized in that the secondary voltage of the ignition coil 1 rises quickly and its peak value is high. However, as shown in FIG. When only the ignition capacitor C1 is provided, it is difficult to extend the duration of the spark discharge generated in the spark plug.
[0012]
Therefore, a plurality of ignition capacitors are provided on the primary side of the ignition coil, and the plurality of ignition capacitors are sequentially discharged at different timings, thereby increasing the duration of spark discharge generated in the ignition plug. 2. Description of the Related Art A discharge type ignition device for an internal combustion engine has been proposed.
[0013]
However, in this type of conventional igniter, the igniter which is assumed in advance without taking into account changes in the state of the load on the secondary side of the ignition coil (the state of the discharge gap of the ignition plug or the state of the air-fuel mixture in the combustion chamber) is considered. Since the timing for discharging the plurality of ignition capacitors is determined based on the ideal state of the secondary load of the coil, the spark discharge is continued when the state of the secondary load of the ignition coil deviates from the ideal state. In some cases (sparks may break).
[0014]
For example, when the engine is accelerated by opening the throttle valve from the idling state or when the engine is suddenly accelerated during operation, the fuel (air-fuel mixture) becomes lean and the discharge starting voltage of the spark plug increases. Therefore, the start of the discharge of the preceding ignition capacitor is delayed, and the waveform of the secondary commutation flowing through the ignition plug changes. Therefore, in order to perform the subsequent discharge without interrupting the preceding discharge, it is necessary to change the timing at which the subsequent discharge is started. Also, when the discharge gap is widened due to exhaustion of the spark plug electrode or when carbon adheres to the electrode, the discharge starting voltage increases, so in order to maintain the discharge, the timing to start the subsequent discharge must be set. It needs to be changed.
[0015]
In the conventional ignition device, since the discharge timing of the plurality of ignition capacitors is constant, it is not possible to cope with the change in the state of the secondary side of the ignition coil as described above, and the spark is not interrupted, In some cases, the intended purpose of obtaining a discharge having a long duration cannot be achieved.
[0016]
SUMMARY OF THE INVENTION It is an object of the present invention to automatically adjust the timing of discharging a plurality of ignition capacitors in accordance with a change in a secondary load (a state of a spark plug or a state in a combustion chamber of an engine) of an ignition coil. Another object of the present invention is to provide a capacitor discharge type internal combustion engine ignition device capable of obtaining a discharge which has a fast rising time, a continuous spark, and a long spark duration.
[0017]
[Means for Solving the Problems]
Automatically adjusts the timing of discharging a plurality of ignition capacitors according to changes in the secondary load of the ignition coil to obtain a discharge with a long spark durationA capacitor discharge type internal combustion engine ignition device includes an ignition coil in which an ignition plug attached to a cylinder of the internal combustion engine is connected to a secondary side, a capacitor charging power supply unit for generating a voltage for capacitor charging, and a primary coil for the ignition coil. And a trigger provided for each of the first and second ignition capacitors and the first and second ignition capacitors that are provided on the sides and are charged to one polarity by the output of the capacitor charging power supply unit. A first and a second discharge switch for conducting when a signal is applied and discharging the electric charges stored in the first and second ignition capacitors through the primary coil of the ignition coil, respectively; An ignition timing control unit for applying a first trigger signal to the first discharge switch, and inducing the primary coil of the ignition coil after the discharge of each ignition capacitor is completed A flywheel diode connected in parallel to the primary coil in a direction in which the pressure is applied in a forward direction, current detecting means for detecting a flywheel current flowing through the flywheel diode, and a flywheel detected by the current detecting means. And a multiple ignition trigger circuit for generating a second trigger signal when the wheel current has attenuated to a set value and applying the second trigger signal to a second discharge switch. The set value of the flywheel current is set to a value equal to or larger than the flywheel current value that flows when the secondary current of the ignition coil has attenuated to the lower limit of the magnitude required to sustain the spark discharge generated in the spark plug.
[0018]
In the above ignition device, the first and second ignition capacitors are charged to one polarity by the output voltage of the capacitor charging power supply unit. When the first discharge switch is turned on at the ignition timing of the internal combustion engine, the electric charge accumulated in the first ignition capacitor is discharged through the first discharge switch and the primary coil of the ignition coil, and the large primary coil is charged to the primary coil. Electric current flows. A high voltage for ignition is induced in the secondary coil of the ignition coil by a change in magnetic flux generated in the iron core of the ignition coil in accordance with the change in the primary current. When the discharge of the first ignition capacitor progresses and the electric charge stored in the capacitor is exhausted, a voltage in a direction in which the primary current that has been flowing so far continues to flow is induced in the primary coil of the ignition coil. Is applied to both ends of the flywheel diode in the forward direction. Therefore, a flywheel current flows from the primary coil of the ignition coil through the flywheel diode. The waveform of the flywheel current is a waveform that sharply rises to a peak when the discharge of the first ignition capacitor is completed, and then attenuates.
[0019]
Spark discharge is generated in the ignition plug by the high voltage for ignition induced in the secondary coil of the ignition coil, and a secondary current flows through the secondary coil. This secondary current starts to flow gradually from the start of discharging of the first ignition capacitor, reaches a peak when the flywheel current starts to flow, and then attenuates. The waveform of the secondary current of the ignition coil slightly changes in accordance with a change in the state of the secondary side of the ignition coil (the state of the discharge gap of the ignition plug, the state of the air-fuel mixture in the combustion chamber, and the like).
[0020]
In the capacitor discharge type ignition device, the change in the process in which the secondary current of the ignition coil attenuates from the peak and becomes zero and the change in the process in which the flywheel current flowing through the flywheel diode attenuates to zero are synchronized. ing. Therefore, by detecting the change in the flywheel current, it is possible to estimate the change in the secondary current of the ignition coil, and that the secondary current of the ignition coil has reached the lower limit necessary for sustaining the spark discharge. Can be estimated from the change in the flywheel current.
[0021]
The above ignition deviceIn the above, a set value of a value equal to or larger than a flywheel current value flowing when the secondary current of the ignition coil attenuates to the lower limit of the magnitude required to maintain the spark discharge generated in the ignition plug is determined in advance, When it is detected that the flywheel current detected by the current detecting means has reached the set value, a trigger signal is supplied to the second discharge switch to discharge the second ignition capacitor.
[0022]
With this configuration, regardless of the state of the secondary side of the ignition coil (particularly, the discharge starting voltage), the spark discharge generated by the high voltage generated by the discharge of the first ignition capacitor is not interrupted. Since the spark discharge can be continued by performing multiple ignitions by the high voltage generated by the discharge of the ignition capacitor of No. 2, a spark discharge which always rises quickly, is not interrupted on the way, and has a long duration is obtained. be able to.
[0023]
The multiple ignition trigger circuit compares the current detection signal obtained from the current detection means with a reference signal and determines whether the magnitude of the current detection signal exceeds the magnitude of the reference signal and the magnitude of the current detection signal. Circuit that generates an output at a level different from that when the magnitude of the reference signal is smaller than the magnitude of the reference signal, and occurs when the magnitude of the current detection signal falls below the magnitude of the reference signal as the flywheel current decays A trigger signal generation circuit for detecting a change in the output level of the comparison circuit and generating a second trigger signal to be applied to the second discharge switch. The magnitude of the reference signal is set to a magnitude corresponding to the set value of the flywheel current.
[0024]
In the above configuration, two ignition capacitors are provided, but in the present invention, the ignition capacitors areProvide three or more.
[0025]
That is, the ignition device according to the present invention includes an ignition coil connected to an ignition plug on the secondary side, a capacitor charging power supply unit for generating a voltage for capacitor charging, and a capacitor charging unit provided on the primary side of the ignition coil. A first to an n-th (n is an integer of 3 or more) ignition capacitors charged to one polarity by the output of the power supply unit, and a first and an n-th ignition capacitor. A first to n-th discharging switch which conducts when a first to n-th trigger signal is applied and discharges a charge stored in each of the first to n-th ignition capacitors through a primary coil of the ignition coil. An ignition timing control unit for providing a first trigger signal to a first discharge switch at the time of ignition of the internal combustion engine; A flywheel diode connected in parallel to the primary coil in a direction in which a voltage induced in the coil is applied in a forward direction, current detection means for detecting a flywheel current flowing through the flywheel diode, the second to n-th trigger signal output terminals connected to the respective trigger signal input terminals of the n discharge switches, and the flywheel current detected by the current detection means has attenuated to a set value. The trigger signal output terminal that outputs a trigger signal each time a signal is detected is shifted from the second trigger signal output terminal to the n-th trigger signal output terminal, so that the second to n-th discharge switches are sequentially switched to the second to n-th discharge switches. And a multiple ignition trigger circuit for providing an nth trigger signal.
[0026]
Also in this case, the set value of the flywheel current is set to be equal to or larger than the flywheel current value that flows when the secondary current of the ignition coil has attenuated to the lower limit of the magnitude necessary to sustain the spark discharge generated in the spark plug. You.
[0027]
In the case where three or more ignition capacitors are provided as described above, the multiple ignition trigger circuit includes a timing signal generation circuit that generates a timing signal when the flywheel current detected by the current detection means attenuates to a set value. And a second to n-th trigger signal output terminals connected to respective trigger signal input terminals of the second to n-th discharge switches, and the timing signal generation circuit generates a timing signal. The trigger signal output terminal, which outputs a trigger signal every time, is sequentially shifted from the second trigger signal output terminal to the nth trigger signal output terminal, so that the second to nth discharge switches are sequentially shifted to the second to nth discharge switches. And a trigger signal shift circuit that supplies an n-th trigger signal.
[0028]
The trigger signal shift circuit can be constituted by, for example, a shift register using a flip-flop circuit.
[0029]
The timing signal generation circuit compares the current detection signal obtained from the current detection means with the reference signal, and determines whether the magnitude of the current detection signal exceeds the magnitude of the reference signal and the magnitude of the current detection signal. And a comparison circuit that generates an output having a different level when the current detection signal is smaller than the reference signal in the process of attenuating the flywheel current. A timing signal output circuit for detecting a change in the output level and outputting a timing signal.
[0030]
When three or more ignition capacitors are provided as described above and the three or more ignition capacitors are sequentially discharged, a spark discharge having a longer duration than when two ignition capacitors are sequentially discharged is performed. Obtainable.
[0031]
In the present invention, it is also possible to adopt a configuration in which multiple ignition is performed only when it is necessary to extend the duration of the spark discharge.
[0032]
That is, a control signal generation circuit for generating a multiple ignition permission signal or a multiple ignition inhibition signal in accordance with the operation state of the internal combustion engine, and a second to n-th trigger signal when the multiple ignition permission signal is generated Is applied to the second to n-th discharging switches, and the second to n-th trigger signals are applied to the second to n-th discharging switches when the multiple ignition prohibition signal is generated. Further, by providing a multiple ignition control circuit for prohibiting the ignition, the multiple ignition can be performed only when it is necessary to extend the duration of the spark discharge.
[0033]
The control signal generation circuit generates the multiple ignition permission signal when rapid acceleration or rapid deceleration of the internal combustion engine is detected, and outputs the multiple ignition inhibition signal when rapid acceleration or rapid deceleration of the internal combustion engine is not detected. It can be configured to occur.
[0034]
The control signal generation circuit may be configured to generate a multiple ignition prohibition signal when the internal combustion engine is started and generate a multiple ignition permission signal after the internal combustion engine is started.
[0035]
When the control signal generation circuit and the multiple ignition control circuit are provided as described above, and the multiple discharge is performed only in the operation state in which the duration of the spark discharge needs to be increased, the duration of the spark discharge is reduced. When it is not necessary to lengthen, the charging voltage of the ignition capacitor can be increased to increase the peak value of the ignition high voltage. Therefore, as in the case of starting the engine, the duration of the spark discharge does not need to be particularly long, and the ignition performance can be improved when the peak value of the high voltage for ignition needs to be increased. If multiple ignition is performed only when necessary, such as when sudden acceleration or sudden deceleration of the engine is detected, the period during which multiple ignition is performed can be shortened, so that consumption of the spark plug is suppressed. can do.
[0036]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG.As a reference example used to explain the principle of the ignition device according to the present invention,1 shows an example of a configuration of one cylinder of a capacitor discharge type internal combustion engine ignition device, in which 1 is an ignition coil having a primary coil 1a and a secondary coil 1b whose one end is grounded, and 2 is an output terminal 2a. A power supply unit for charging a capacitor having an output terminal 2a grounded and having an output terminal 2b, and an ignition timing control unit 3 for outputting a trigger signal Vt at the ignition timing of the internal combustion engine.
[0037]
Ignition device shown in FIG., One ends of the first and second ignition capacitors C11 and C12 are connected to the non-ground side terminal of the primary coil 1a of the ignition coil, and the other ends of the ignition capacitors C11 and C12 have cathodes connected to these capacitor sides. It is connected to the non-ground side output terminal of the capacitor charging power supply unit 2 through the directed diodes D11 and D12.
[0038]
The other ends of the ignition capacitors C11 and C12 are connected to the anodes of first and second thyristors Th1 and Th2 constituting first and second discharge switches, respectively, and the cathodes of these thyristors are grounded. . The gate of the first thyristor Th1 is connected to the output terminal of the ignition timing control unit 3, so that the ignition timing control unit 3 supplies the first trigger signal Vt1 to the first thyristor Th1 at the ignition timing of the internal combustion engine. ing.
[0039]
The output signal of the pulsar coil PC provided in the signal generator attached to the internal combustion engine is input to the ignition timing control unit 3. The illustrated pulsar coil PC has a negative first pulse signal Vs1 at a first rotation angle position θ1 set at a position sufficiently advanced from the top dead center of the engine as shown in FIG. 3A, for example. And a second pulse signal Vs2 having a positive polarity is generated at a second rotation angle position θ2 that is delayed from the first rotation angle position and slightly advanced from the top dead center of the engine. The ignition timing control unit 3 includes, for example, a microcomputer, and calculates the ignition timing at each rotation speed using the rotation angle information and the rotation speed information obtained from the output pulse of the pulsar coil PC, and detects the calculated ignition timing. When this is done, a first trigger signal Vt1 is output as shown in FIG.
[0040]
In FIGS. 3A to 3L, θ on the horizontal axis indicates the rotation angle of the crankshaft of the engine.
[0041]
The anode of a flywheel diode D2 is connected to the non-ground terminal of the primary coil 1a of the ignition coil 1, and a current detecting resistor R1 is connected between the cathode of the diode and ground. The flywheel diode D2 is connected to the primary coil 1a when the primary current flowing from the ignition capacitors C11 and C12 through the primary coil 1a of the ignition coil through the discharge switches Th1 and Th2 respectively disappears (when the charge of the ignition capacitor is exhausted). The induced voltage (voltage in the direction in which the primary current is to be kept flowing) is connected in parallel to the primary coil 1a in a direction to be applied in the forward direction. In this example, a current detecting means 4 for detecting a flywheel current flowing through a flywheel diode D2 by a resistor R1 is formed.
[0042]
The non-ground side terminal of the resistor R1 constituting the current detecting means 4 is connected to the non-ground side input terminal of the multiple ignition trigger circuit 5, and the output terminal of the multiple ignition trigger circuit 5 is connected to the second thyristor Th2. Connected to the gate. The non-ground side terminal of the secondary coil 1b of the ignition coil is connected to the non-ground side terminal of a spark plug P attached to a cylinder of the engine.
[0043]
The capacitor charging power supply unit 2 outputs a voltage (a voltage of about 200 to 250 [V]) for charging the ignition capacitors C11 and C12. The power supply unit 2 is attached to an internal combustion engine. An exciter coil provided in the magnet generator to output an AC voltage in synchronization with the rotation of the engine, a power supply circuit in which the output voltage of the generator coil provided in the magnet generator is boosted by a chopper circuit, A power supply circuit in which the output voltage is boosted by a DC-DC converter can be used.
[0044]
When the capacitor charging power supply unit 2 is configured to generate an output voltage for capacitor charging even at the ignition timing (for example, when the power supply unit 2 includes a battery and a DC-DC converter), In order to facilitate the commutation of the thyristors Th1 and Th2 constituting the discharge switch, the power supply unit 2 stops the output during the ignition operation.
[0045]
The multiple ignition trigger circuit 5 is configured to generate a second trigger signal Vt2 when the flywheel current detected by the current detecting means 4 has attenuated to the set value Ifs, and to generate the second trigger signal Vt2. Vt2 is given to the gate of the thyristor Th2 constituting the second discharge switch.
[0046]
The set value Ifs of the flywheel current is set to be equal to or larger than the flywheel current value that flows when the secondary current of the ignition coil has attenuated to the lower limit of the magnitude required to maintain the spark discharge generated in the spark plug. .
[0047]
In the ignition device shown in FIG. 1, a first ignition capacitor C11 and a second ignition capacitor C12 are shown through diodes D11 and D12 and a primary coil 1a of an ignition coil according to an output voltage of a capacitor charging power supply unit 2. Is charged to the polarity. Accordingly, the voltage Vc1 across the first ignition capacitor C11 and the voltage Vc2 across the second ignition capacitor C12 are shown in FIGS. 3 (C) and 3 (I) as the crankshaft rotation angle θ changes. And so on.
[0048]
When the ignition timing control unit 3 generates the first trigger signal Vt1 at the rotational angle position θi corresponding to the ignition timing of the internal combustion engine, the first thyristor Th1 conducts. As a result, the electric charge stored in the first ignition capacitor C11 is discharged through the first thyristor Th1 and the primary coil 1a of the ignition coil, and a large primary current (discharge current) I11 (FIG. 3D) flows through the primary coil 1a. Flows. A high voltage for ignition is induced in the secondary coil 1b of the ignition coil by a change in magnetic flux generated in the iron core of the ignition coil 1 with the change in the primary current, and the high voltage is applied to the ignition plug P. When the high voltage applied to the ignition plug P exceeds the discharge starting voltage, a spark discharge occurs in the gap of the ignition plug, and the secondary current I21 (see FIG. 3L) flows through the secondary coil of the ignition coil. When the discharge of the first ignition capacitor C11 progresses and the electric charge stored in the ignition capacitor is exhausted, a voltage in the direction of continuing to flow the primary current I1 which has been flowing until now is applied to the primary coil of the ignition coil. And this voltage is applied in the forward direction across the flywheel diode D2. Therefore, as shown in FIG. 3K, a flywheel current If1 flows from the primary coil 1a of the ignition coil 1 through the flywheel diode D2. The waveform of the flywheel current If1 is a waveform that sharply rises to its peak when the discharge of the first ignition capacitor C11 is completed and then attenuates.
[0049]
As shown in FIG. 3 (L), the waveform of the secondary current I21 of the ignition coil that flows when a spark discharge is generated in the ignition plug P at a high voltage generated by the discharge of the first ignition capacitor C11, as shown in FIG. The current gradually starts flowing from the start of discharge of the capacitor for use, and reaches a peak when the flywheel current If1 starts flowing, and then attenuates. The waveform of the secondary current I21 slightly changes according to a change in the state of the secondary side of the ignition coil (the state of the discharge gap of the ignition plug, the state of the air-fuel mixture in the combustion chamber, and the like).
[0050]
In the capacitor discharge type ignition device, the change in the process in which the secondary current I21 of the ignition coil 1 attenuates from the peak and becomes zero, and the change in the process in which the flywheel current If1 flowing through the flywheel diode D2 attenuates to zero. Changes are in sync. Therefore, by detecting the change in the flywheel current If1, the change in the secondary current I21 of the ignition coil can be estimated, and the secondary current I21 of the ignition coil reaches the lower limit necessary for sustaining the discharge. This can be estimated from the change in the flywheel current.
[0051]
In the ignition device shown in FIG. 1, when the flywheel current If1 detected by the current detection means 4 reaches the set value Ifs, the multiple ignition trigger circuit 5 sends a second trigger signal to the second thyristor Th2. Vt2. As a result, the second thyristor Th2 conducts, and the electric charge of the second ignition capacitor C12 is discharged through the primary coil of the ignition coil. Due to this discharge, a primary current I12 (FIG. 3J) flows through the ignition coil 1, and a high voltage is again generated in the secondary coil of the ignition coil. When this high voltage is applied to the ignition plug P, a secondary current I22 (FIG. 3L) flows through the ignition coil 1. Even after the discharge of the second ignition capacitor C12 is completed, the flywheel current If2 flows through the flywheel diode D2. The waveform of the flywheel current If2 is as shown in FIG.
[0052]
Ignition device shown in FIG.In this case, the set value Ifs of the flywheel current If is equal to or larger than the flywheel current value flowing when the secondary current I2 of the ignition coil is attenuated to the lower limit of the magnitude required to sustain the spark discharge generated in the spark plug P. Irrespective of the state of the secondary side of the ignition coil 1, the second ignition capacitor is discharged in a state where spark discharge always occurs in the ignition plug P and the subsequent capacitor is discharged. A high voltage for ignition can be generated. Therefore, the high voltage generated by the discharge of the second ignition capacitor C2 is applied to the spark plug without interrupting the spark discharge generated by the high voltage generated by the discharge of the first ignition capacitor, and the multiple ignition is performed. Regardless of the state of the electrode of the spark plug or the state of the air-fuel mixture in the combustion chamber, a rapid start-up can be achieved without interruption, and a spark discharge with a long duration can be obtained. it can.
[0053]
In the ignition device shown in FIG. 1, when charging the ignition capacitors C11 and C12, a voltage is applied across the series circuit of the flywheel diode D2 and the resistor R1, but the flywheel diode D2 and the resistor Since the impedance of the series circuit with R1 is sufficiently larger than the impedance of the primary coil 1a of the ignition coil, a small amount of current flows through the flywheel diode D2 when the capacitors C11 and C12 are charged. Therefore, the multiple ignition trigger circuit 5 does not generate a trigger signal by the detection signal of the current flowing through the flywheel diode D2 when the capacitors C11 and C12 are charged.
[0054]
The multiple ignition trigger circuit 5 used in the ignition device of FIG. 1 can be configured, for example, as shown in FIG. In FIG. 2, parts that are the same as the parts shown in FIG. 1 are given the same reference numerals. In this example, a current detection signal Vi obtained at both ends of a resistor R1 constituting the current detection means 4 is input to an inverting input terminal of a comparator CP1 through a resistor R2. A reference signal Vr obtained by dividing the output voltage Vb of a constant voltage DC power supply circuit (not shown) by a voltage dividing circuit including resistors R3 and R4 is input to the non-inverting input terminal of the comparator CP1. The magnitude of the reference signal Vr is set to a magnitude corresponding to the set value of the flywheel current (so that the output of the comparator CP1 is inverted when the flywheel current reaches the set value).
[0055]
One end of a differential capacitor C2 is connected to the output terminal of the comparator CP1, and the other end of the capacitor C2 is connected to the base of a transistor TR1 whose emitter is grounded. A diode D3 having an anode directed to the ground is connected between the base and the emitter of the transistor TR1, and a connection point between one end of the capacitor C2 and the output terminal of the comparator CP1 is connected to a DC constant voltage power supply (not shown) through a resistor R5. I have. The collector of the transistor TR1 is connected through a resistor R6 to the base of a PNP transistor TR2, and a resistor R7 is connected between the emitter and the base of the transistor TR2. One end of a resistor R8 is connected to the collector of the transistor TR2, and the other end of the resistor R8 is connected to the gate of a second thyristor Th2 constituting a second discharging switch.
[0056]
In this example, the comparator CP1 and the resistors R2 to R4 compare the current detection signal Vi obtained from the current detection means 4 with the reference signal Vr so that the magnitude of the current detection signal Vi exceeds the magnitude of the reference signal Vr. The comparison circuit 5A generates an output voltage having a different level when the current detection signal Vi is smaller than the reference signal Vr when the current detection signal Vi is smaller than the reference signal Vr. Also, the output of the comparison circuit generated when the magnitude of the current detection signal falls below the magnitude of the reference signal in the process of attenuating the flywheel current is determined by the transistor TR1, the differential capacitor C2, the diode D3, and the resistor R5. A differential signal 501 for generating a differential pulse by differentiating a change in the level of the trigger signal is provided. A trigger signal output circuit 502 for inverting the differential pulse by a transistor TR2 and resistors R6 to R8 and outputting a second trigger signal Vt2 is provided. It is configured. By the differentiating circuit 501 and the trigger signal output circuit 502, the level of the output level of the comparison circuit 5A generated when the magnitude of the current detection signal Vi falls below the magnitude of the reference signal Vr in the process of attenuating the flywheel current. A trigger signal generating circuit 5B for detecting a change and generating a second trigger signal Vt2 to be applied to the second discharge switch is configured.
[0057]
Other configurations of the ignition device shown in FIG. 2 are the same as those of the ignition device shown in FIG. In the ignition device shown in FIG. 2, when no flywheel current is flowing, the output voltage V1 of the comparator CP1 is at a high level as shown in FIG. 3 (F). At this time, the differential capacitor C2 is charged through the resistor R5, and the voltage V2 across the capacitor C2 is at a high level as shown in FIG. When the flywheel current If1 flowing after the discharge of the first ignition capacitor C11 is completed exceeds the set value Ifs and the current detection signal Vi becomes larger than the reference signal Vr, the output voltage V1 of the comparator CP1 becomes low (ground potential). ). As a result, the electric charge stored in the differential capacitor C2 is discharged through the output stage of the comparator CP1 and the diode D3, so that the voltage V2 across the differential capacitor C2 becomes zero (see FIG. 3G). When the flywheel current If1 becomes smaller than the set value Ifs and the magnitude of the current detection signal Vi becomes smaller than the magnitude of the reference signal Vr, the output voltage V1 of the comparator CP1 rises to a high level. Charged through R5, the voltage across the differential capacitor C2 rises as shown in FIG. While the differentiation capacitor C2 is being charged, a base current flows through the transistor TR1 to turn on the transistor TR1, and the transistor TR2 is turned on while the transistor TR1 is turned on. Accordingly, as shown in FIG. 3H, the trigger signal Vt2 is supplied to the second thyristor Th2 through the transistor TR2 and the resistor R8.
[0058]
FIGS. 4A to 4H show how the waveforms of the primary current, the secondary current, and the flywheel current change when the state of the load on the secondary side of the ignition coil changes. The waveforms of the first trigger signal Vt1 and the terminal voltages of the ignition capacitors C11 and C12 are shown together with the waveforms of the output signal of the pulsar coil and the waveform of the first trigger signal Vt1. FIGS. 4C and 4D show the waveforms of the terminal voltages Vc1 and Vc2 of the first and second ignition capacitors C11 and C12, respectively. FIGS. 4E and 4F show waveforms of primary currents I11 and I12 flowing when the first ignition capacitor C11 and the second ignition capacitor C12 are discharged, respectively. (H) shows the waveforms of the flywheel currents If1, If2 and the secondary currents I21, I22 of the ignition coil, respectively. 4 (F) to 4 (H), the waveform shown by a solid line shows the waveform when the discharge starting voltage of the ignition plug connected to the secondary side of the ignition coil is low, and the waveform shown by the broken line shows the discharge of the ignition plug. The waveform when the starting voltage is high is shown.
[0059]
When the discharge starting voltage of the spark plug P is low, the second trigger signal is generated when the flywheel current If1 shown by the solid line in FIG. 4 (G) attenuates to the set value Ifs, and the second thyristor Th2 becomes conductive. Then, the second ignition capacitor C12 is discharged, and the primary current I12 flows as shown by the solid line in FIG. As a result, a high voltage is induced in the secondary coil of the ignition coil, and when the high voltage reaches the discharge starting voltage of the ignition plug, discharge occurs in the ignition plug P, as shown by the solid line in FIG. The secondary current I21 flows.
[0060]
On the other hand, when the discharge start voltage of the ignition plug P becomes high, it takes time for the secondary voltage of the ignition coil to reach the discharge start voltage. Therefore, as shown by a broken line in FIG. After the primary current I11 starts to flow, a time delay occurs before the secondary current I21 starts to flow, and the peak of the secondary current I21 also tends to decrease. The duration of the generated discharge tends to be shorter. At this time, as indicated by a broken line in FIG. 4G, the flywheel current If1 also tends to decrease, and the position where the flywheel current If1 attenuates and becomes equal to the set value Ifs advances. The discharge start position of the second ignition capacitor C12 is advanced by an amount corresponding to the decrease of I21, and the spark discharge generated in the ignition plug is prevented from being interrupted.
[0061]
Thus, the ignition coilThe magnitude of the flywheel current showing a tendency of change similar to that of the secondary current is detected, and the flywheel current is set to a set value (lower limit value of the secondary current necessary for continuing discharge at the spark plug). (The flywheel current value is set to be equal to or greater than the flywheel current value).ThenRegardless of the state of the load on the secondary side of the ignition coil (discharge start voltage of the ignition plug), the spark discharge generated in the ignition plug by the discharge of the first ignition capacitor is not interrupted, and the second ignition By starting the discharge of the capacitor, the duration of the spark discharge generated in the spark plug can be extended.
[0062]
aboveReference exampleHas two ignition capacitors C11 and C12 on the primary side of the ignition coil.In the present invention,By providing three or more ignition capacitors and sequentially discharging the three or more ignition capacitors, the duration of spark discharge can be further increased.Be able to make it longer.FIG. 5 shows an example in which a first ignition capacitor C11 to a third ignition capacitor C13 are provided on the primary side of the ignition coil 1. The first ignition capacitor C11 to the third ignition capacitor C13 are shown. Is connected to the non-ground side terminal of the primary coil 1a of the ignition coil, and the other ends of the first to third ignition capacitors C11 to C13 are diodes each having a cathode directed toward the corresponding ignition capacitor. It is connected to the non-ground side output terminal of the capacitor charging power supply unit 2 through D11 to D13. Further, first to third thyristors Th1 to Th3 constituting first to third discharge switches are connected between the other ends of the ignition capacitors C11 to C13 and the ground with their respective cathodes facing the ground. The gate of the first thyristor Th1 is supplied with a first trigger signal Vt1 from an output terminal (first trigger signal output terminal) t1 of the ignition timing controller 3.
[0063]
The multiple ignition trigger circuit 5 receives a current detection signal Vi obtained from the current detection means 4 as an input, and generates a timing signal Vo when the flywheel current attenuates to a set value Ifs. And second and third output terminals t2 and t3 connected to respective trigger signal input terminals (gates of thyristors Th2 and Th3) of the discharge switch and the third discharge switch, respectively, to generate a timing signal. Each time the circuit 5a generates the timing signal Vo, the output terminal for outputting the trigger signal is shifted from the second output terminal to the third output terminal, so that the second and third discharge switches (Th2 and Th3) are output. ) And a trigger signal shift circuit 5b for sequentially supplying the second and third trigger signals Vt2 and Vt3.
[0064]
The timing signal generation circuit 5a can be configured by the same circuit as the trigger circuit 5 shown in FIG. That is, in the ignition device shown in FIG. 5, the second trigger signal Vt2 used in the ignition device of FIG. 2 may be used as the timing signal Vo.
[0065]
The trigger signal shift circuit 5b includes a well-known flip-flop circuit 510 having a positive logic output terminal Q1 and a negative logic output terminal Q2, and inverting the potentials of the output terminals Q1 and Q2 each time the timing signal Vo is applied. A differentiating circuit 511 for differentiating the rising edge of the signal obtained at the output terminal Q1 of the circuit 510 and outputting a second pulsed trigger signal Vt2 to the output terminal t2; and a differential circuit 511 for outputting the signal obtained at the output terminal Q2 of the flip-flop circuit 510. A differentiation circuit 512 for differentiating the rising edge and outputting a pulse-like third trigger signal Vt3 to an output terminal t3. The differentiating circuit 511 comprises a capacitor C3 connected between the output terminal of the flip-flop circuit 510 and the gate of the thyristor Th2, and a resistor R10 connected between the thyristor Th2 side terminal of the capacitor C3 and the ground. Reference numeral 512 denotes a capacitor C4 connected between the output terminal of the flip-flop circuit 510 and the gate of the thyristor Th3, and a resistor R11 connected between the thyristor Th3 side terminal of the capacitor C4 and the ground.
[0066]
In the ignition device shown in FIG. 5, when the ignition timing control unit 3 generates the first trigger signal Vt1, the first thyristor Th1 conducts to discharge the charge of the first ignition capacitor C11, and the ignition coil is connected to the ignition coil. The primary current I11 flows. Thereby, a high voltage for ignition is generated in the secondary coil of the ignition coil. When this high voltage reaches the discharge starting voltage, a secondary current I21 flows through the ignition coil. After the discharge of the first ignition capacitor C11 is completed, the flywheel current If1 flowing through the flywheel diode D2 attenuates to a set value, and when the current detection signal Vi decreases to the magnitude of the reference signal, the timing signal generating circuit 5a Generates a timing signal Vo. When the timing signal Vo is generated, the potential of the output terminal Q1 of the flip-flop circuit 510 rises to a high level, and the second trigger signal Vt2 is given to the gate of the second thyristor Th2 through the differentiating circuit 511. As a result, the second thyristor Th2 is turned on, the electric charge stored in the second ignition capacitor C12 is discharged, and the primary current I12 flows through the ignition coil. Due to this change in the primary current, a high voltage is generated on the secondary side of the ignition coil, and the secondary current I22 flows through the ignition coil. When the flywheel current If2 flowing after the discharge of the ignition capacitor C12 is completed attenuates to a set value, a timing signal Vo is generated again, so that the potential of the output terminal Q1 of the flip-flop circuit 510 decreases, and the potential of the output terminal Q2 decreases. The potential rises. The rise in the potential is differentiated by the differentiating circuit 512 and converted into a pulse signal, and the third trigger signal Vt3 is given to the third thyristor Th3. As a result, the third thyristor Th3 conducts, and the electric charge of the third ignition capacitor C13 is discharged, so that the primary current I13 flows through the ignition coil. As a result, a high voltage is generated in the secondary coil of the ignition coil, and a secondary current I23 flows.
[0067]
The electric charges accumulated in the capacitors C3 and C4 of the differentiating circuits 511 and 512 are stored in the flip-flop circuit when the potentials of the output terminals Q1 and Q2 of the flip-flop circuit to which the respective capacitors are connected decrease (when the potentials reach the ground potential). Discharged instantaneously through the output stage.
[0068]
Generally, when the first to n-th ignition capacitors C11 to C1n and the first to n-th discharge switches for discharging these capacitors are provided on the primary side of the ignition coil, the second to n-th discharge capacitors are provided. The second to n-th trigger signal output terminals t2 to tn connected to the respective trigger signal input terminals of the switch for setting the flywheel currents If1 to Ifn-1 detected by the current detecting means 4. By shifting the trigger signal output terminal for outputting a trigger signal every time the value is detected to have decreased to the value from the second trigger signal output terminal t2 to the nth trigger signal output terminal tn, A multiple ignition trigger circuit for sequentially providing the second to n-th trigger signals Vt2 to Vtn to the discharge switch is provided.
[0069]
The multiple ignition trigger circuit includes a timing signal generation circuit for generating a timing signal Vo when the flywheel current detected by the current detection means 4 has attenuated to a set value, a second discharge switch or an n-th discharge switch. The discharge switch has second to nth trigger signal output terminals t2 to tn connected to respective trigger signal input terminals of the discharge switch, and outputs a trigger signal each time the timing signal generating circuit generates a timing signal. By sequentially shifting the trigger signal output terminal from the second trigger signal output terminal to the nth trigger signal output terminal, the second to nth trigger signals are sequentially supplied to the second to nth discharge switches. It can be constituted by a trigger signal shift circuit. The trigger signal shift circuit can be constituted by, for example, a shift register using a flip-flop circuit.
[0070]
In the examples shown in FIGS. 1, 2 and 5, respectively, the ignition capacitor is connected in series with the primary coil of the ignition coil so that the charging current of the ignition capacitor flows through the primary coil of the ignition coil. However, the present invention can be applied to a case where a circuit configured to charge the ignition capacitor without passing through the primary coil of the ignition coil is used.
[0071]
FIG. 6 shows an example in which the ignition capacitor is charged without passing the primary coil of the ignition coil, and corresponds to the ignition device shown in FIG. In the example of FIG. 6, one ends of the first and second ignition capacitors C11 and C12 are grounded, and the other ends of the capacitors C11 and C12 are used for charging the capacitors through diodes D11 and D12 whose cathodes are directed toward the respective capacitors. It is connected to the non-ground side output terminal of the power supply unit 2. The first and second thyristors Th1 and Th2 constituting the first and second discharge switches are respectively connected between the non-ground terminals of the capacitors C11 and C12 and the non-ground terminal of the primary coil 1a of the ignition coil 1. It is connected. The flywheel diode D2 is provided with its cathode facing the non-ground terminal of the primary coil 1a of the ignition coil, and the current detecting resistor R1 is connected between the anode of the flywheel diode D2 and ground. .
[0072]
The operation of the ignition device shown in FIG. 6 is the same as the operation of the ignition device shown in FIG. In the case of the configuration as shown in FIG. 6, no current flows through the flywheel diode D2 when charging the ignition capacitors C11 and C12, so that the current flowing through the flywheel diode is generated in the current detecting means 4. The possibility that the current detection signal is given to the multiple ignition trigger circuit 5 as noise can be eliminated.
[0073]
Even when three or more ignition capacitors are provided on the primary side of the ignition coil, it goes without saying that the same configuration as that of FIG. 6 can be adopted.
[0074]
In each of the above examples, multiple ignitions are always performed during operation of the engine.However, if multiple ignitions are performed in the entire rotation range of the engine, it is necessary to constantly charge a plurality of ignition capacitors. There is a possibility that the charging voltage of the capacitor for use decreases, and the peak value of the high voltage induced on the secondary side of the ignition coil becomes lower than when multiple ignition is not performed. In particular, when the charging voltage of the ignition capacitor decreases at the time of starting the engine, it may be difficult to start the engine. It is not always necessary to perform multiple ignitions over the entire rotation range of the engine. In most cases, the mixture becomes particularly lean, for example, when the engine is rapidly accelerated or decelerated. Only when it is difficult to arrive, the multiple ignition is performed to extend the duration of the spark discharge.
[0075]
Therefore, it is desirable that the ignition device according to the present invention be capable of performing the multiple ignitions only when necessary so as to extend the duration of the spark discharge. FIG. 7 shows an example in which multiple ignition can be performed only when necessary. In this example, in addition to the configuration shown in FIG. 1, a high-level ("1" state) A control signal generating circuit 6 for outputting a multiple ignition permission signal Vm1 and a low level ("0") multiple ignition prohibition signal Vm2; and the control signal generation circuit 6 generates a multiple ignition permission signal. The thyristor Th2 that constitutes the second discharge switch when the trigger signal is supplied to the thyristor Th2, and prohibits the thyristor Th2 from receiving the trigger signal when the multiple ignition inhibition signal is generated. A fire control circuit 7 is provided. In the illustrated example, the multiplex control circuit 7 comprises an AND circuit 7, the output of the control signal generation circuit 6 is input to the AND circuit AND1 together with the output of the multiple ignition trigger circuit 5, and the output of the AND circuit is output to the AND circuit AND1. 2 is supplied to the gate of the second thyristor Th2.
[0076]
In the ignition device shown in FIG. 7, when the control signal generating circuit 6 outputs the high-level multiple ignition permission signal Vm1 as shown in the left half of FIG. When the circuit 5 generates a trigger signal, the AND condition of the AND circuit AND1 is satisfied, and the trigger signal Vt2 is supplied to the thyristor Th2, so that the thyristor Th2 conducts and the multiplex point is set as shown in the left half of FIG. A fire takes place. On the other hand, as shown in the right half of FIG. 9 (M), when the control signal generating circuit 6 generates the low level multiple ignition prohibition signal Vm2, the multiple ignition trigger circuit 5 Occurs, the AND condition of the AND circuit AND1 is not satisfied, so that the trigger signal Vt2 is not supplied to the thyristor Th2, and multiple ignition is not performed as shown in the right half of FIG. When multiple ignition is not performed, the ignition capacitor C12 is maintained in a charged state, so that all the outputs of the capacitor charging power supply unit 2 are used for charging the capacitor C11. Therefore, the charging voltage of the capacitor C11 can be sufficiently increased, and the peak value of the ignition high voltage induced in the secondary coil of the ignition coil can be increased.
[0077]
The multiple ignition control circuit 6 outputs the multiple ignition permission signal Vm1 at the time of rapid acceleration or rapid deceleration of the engine, for example, where the duration of the spark discharge needs to be extended, and outputs the multiple ignition permission signal Vm1 at the time of starting the engine and the rotation speed of the engine. When the rate of change over time is small, a multiple ignition prohibition signal Vm2 is output. Sudden acceleration and sudden deceleration of the engine can be detected by obtaining a temporal change rate of a signal voltage proportional to the rotational speed of the engine and comparing the temporal change rate with a set value.
[0078]
The control signal generating circuit 6 is configured to generate a multiple ignition prohibition signal at the start of an engine that requires a particularly high peak value of the ignition high voltage, and to generate a multiple ignition permission signal after the engine is started. You can also.
[0079]
FIG. 8 shows a more specific example of each part in FIG. In the example shown in FIG. 8, the multiple ignition trigger circuit 5 is configured similarly to the example shown in FIG. The control signal generation circuit 6 detects the presence or absence of sudden acceleration and sudden deceleration of the engine, generates a high-level acceleration detection signal when the sudden acceleration or sudden deceleration is detected, and does not detect the sudden acceleration and sudden deceleration. An acceleration detection circuit 6A that sometimes generates a low level signal, and an inversion circuit 6B that inverts a signal output from the acceleration detection circuit 6A to generate a multiple ignition permission signal Vm1 and a multiple ignition inhibition signal Vm2. I have. The inverting circuit 6B is connected between an NPN transistor TR3 whose emitter is grounded, a resistor R20 connected between the base of the transistor TR3 and the output terminal of the control signal generating circuit 6, and a base and emitter of the transistor TR3. An AND circuit is formed by connecting the collector of the transistor TR3 to the output terminal of the multiple ignition trigger circuit 5, and the multiple ignition control circuit 7 is formed. Other configurations are the same as the configuration of the ignition device shown in FIG.
[0080]
In the ignition device shown in FIG. 8, when rapid acceleration and rapid deceleration of the engine are not detected, since the acceleration detection circuit 6A generates a low-level signal, the transistor TR3 holds the cut-off state. The potential of the collector of the transistor TR3 is at a high level (a state in which the multiple ignition permission signal Vm1 is generated). In this state, the trigger signal Vt2 is supplied to the thyristor Th2 when the trigger circuit 5 for multiple ignition outputs the trigger signal, so that multiple ignition is performed as shown in the left half of FIG. 9 (M).
[0081]
On the other hand, when rapid acceleration or rapid deceleration of the engine is detected, the acceleration detection circuit 6A generates a high-level acceleration detection signal, so that the transistor TR3 is turned on and the collector of the transistor TR3 is turned on. The potential becomes a low level (a state in which the multiple ignition prohibition signal Vm2 is generated). In this state, since the trigger signal Vt2 is not supplied to the thyristor Th2 when the trigger circuit 5 for multiple ignition outputs the trigger signal, the multiple ignition is not performed as shown in the right half of FIG. The ignition capacitor C12 is kept charged.
[0082]
The waveforms shown in the left half of FIGS. 9A to 9L are the same as the waveforms shown in FIGS. 3A to 3L, and are the same as those shown in FIGS. 9A to 9L. The waveforms shown in the halves are that (H) the trigger signal Vt2 is not generated, (I) the terminal voltage Vc2 of the capacitor C12 is held, (J) the primary current I12 does not flow, and ( It is the same as that shown in FIG. 3 except that the secondary current waveform of L) is no longer a multiple discharge current waveform.
[0083]
In the examples shown in FIGS. 7 and 8, two ignition capacitors are provided on the primary side of the ignition coil. However, when three or more ignition capacitors are provided, the multiple ignition It can be provided so that multiple ignition is performed only when necessary.
[0084]
In the above example, a thyristor is used as the discharging switch, but the discharging switch may be constituted by another semiconductor switch such as an FET.
[0085]
【The invention's effect】
As described above, according to the present invention, the current detection means for detecting the flywheel current that changes in synchronization with the secondary current of the ignition coil is provided, and the secondary current of the ignition coil is generated by the spark discharge generated in the spark plug. The flywheel current that flows when the discharge of the preceding capacitor is completed is set in advance, and the flywheel current that flows after the discharge of the preceding capacitor is completed is set in advance. Since the discharge of the subsequent capacitor is started when it is detected that the voltage has attenuated, the discharge of the first ignition capacitor can be performed regardless of the state of the secondary side of the ignition coil (in particular, the discharge start voltage). The discharge is continued by the high voltage generated by the subsequent discharge of the ignition capacitor without interrupting the spark discharge generated by the generated high voltage. Rukoto can. Therefore, a spark discharge can be obtained in which the start-up is always fast, there is no break in the middle, and the duration is long, and the loading performance in a state where the air-fuel mixture is lean can be improved.
[0086]
In the present invention, when a multiple ignition control circuit is provided to perform multiple ignition only when necessary, the charging voltage of the ignition capacitor is increased when multiple ignition is not required. The peak value of the high voltage for ignition can be increased.
[0087]
Further, when multiple ignition is performed only when rapid acceleration or rapid deceleration of the engine is detected, the period during which multiple ignition is performed can be shortened, so that consumption of the spark plug is suppressed. be able to.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration example of a capacitor discharge type ignition device for an internal combustion engine according to the present invention.
FIG. 2 is a circuit diagram showing a more specific example of each part of the capacitor discharge type internal combustion engine ignition device shown in FIG.
FIG. 3 is a waveform diagram showing a voltage or current waveform of each part of the ignition device of FIGS. 1 and 2;
FIG. 4 is a waveform diagram showing the voltage or current waveform of each part of the ignition device of FIGS. 1 and 2 when the firing voltage of the spark plug is high and when it is low.
FIG. 5 is a circuit diagram showing another example of the configuration of the ignition device for a capacitor discharge type internal combustion engine according to the present invention.
FIG. 6 is a circuit diagram showing still another configuration example of the capacitor discharge type ignition device for an internal combustion engine according to the present invention.
FIG. 7 is a circuit diagram showing still another configuration example of the capacitor discharge type internal combustion engine ignition device according to the present invention.
8 is a circuit diagram showing an example in which each part of the ignition device shown in FIG. 7 is further concretely illustrated.
FIG. 9 is a waveform diagram showing a voltage or current waveform of each part of the ignition device of FIG. 8;
FIG. 10 is a circuit diagram showing a configuration of a conventional capacitor discharge ignition system for an internal combustion engine.
[Explanation of symbols]
1 ignition coil
2 Power supply for capacitor charging
3 Ignition timing control section
4 Current detection means
5 Trigger circuit for multiple ignition
C11, C12, C13 Ignition capacitor
Thyristor constituting Th1, Th2, Th3 discharge switch
D2 flywheel diode
P Spark plug

Claims (6)

An ignition coil in which an ignition plug attached to a cylinder of the internal combustion engine is connected to a secondary side,
  A capacitor charging power supply for generating a capacitor charging voltage;
  First to n-th (n is an integer of 3 or more) ignition capacitors provided on the primary side of the ignition coil and charged to one polarity by an output of the capacitor charging power supply unit;
  Each of the first to n-th ignition capacitors is provided, and becomes conductive when a first to n-th trigger signal is applied, and is stored in the first to n-th ignition capacitors. First to n-th discharging switches for discharging the charged electric charge through the primary coil of the ignition coil;
  An ignition timing control unit for providing a first trigger signal to the first discharge switch at an ignition timing of the internal combustion engine;
  A flywheel diode connected in parallel to the primary coil in a direction in which the voltage induced in the primary coil of the ignition coil is applied in the forward direction after the discharge of each ignition capacitor is completed,
  Current detection means for detecting a flywheel current flowing through the flywheel diode,
  It has a second to nth trigger signal output terminals connected to respective trigger signal input terminals of the second to nth discharge switches, and sets a flywheel current detected by the current detection means. By shifting the trigger signal output terminal for outputting a trigger signal every time it is detected that the signal has attenuated to the value from the second trigger signal output terminal to the nth trigger signal output terminal, A multi-ignition trigger circuit for sequentially providing second to n-th trigger signals to the switch;
  The set value of the flywheel current is set to be equal to or larger than a flywheel current value that flows when the secondary current of the ignition coil attenuates to a lower limit of a magnitude necessary for sustaining a spark discharge generated in a spark plug. An ignition device for a capacitor discharge internal combustion engine, comprising: The multiple ignition trigger circuit,
  A timing signal generation circuit that generates a timing signal when the flywheel current detected by the current detection means attenuates to a set value;
  A timing signal generating circuit for generating a timing signal having a second to n-th trigger signal output terminals connected to respective trigger signal input terminals of the second to n-th discharge switches; The trigger signal output terminal, which outputs a trigger signal every time, is sequentially shifted from the second trigger signal output terminal to the nth trigger signal output terminal, so that the second to nth discharge switches are sequentially shifted to the second to nth discharge switches 2. The ignition device for a capacitor discharge type internal combustion engine according to claim 1, further comprising a trigger signal shift circuit for supplying an nth trigger signal. The timing signal generation circuit includes:
  The current detection signal obtained from the current detection means is compared with a reference signal, and when the magnitude of the current detection signal exceeds the magnitude of the reference signal, the magnitude of the current detection signal is larger than the magnitude of the reference signal. A comparison circuit that generates an output with a different level when the signal is small;
  The timing of detecting the change in the output level of the comparison circuit that occurs when the magnitude of the current detection signal falls below the magnitude of the reference signal in the process of the flywheel current being attenuated, and outputting the timing signal. 3. The ignition device for a capacitor discharge internal combustion engine according to claim 2, further comprising a signal output circuit. A control signal generation circuit for generating a multiple ignition permission signal or a multiple ignition inhibition signal in accordance with an operation state of the internal combustion engine; and the second to n-th trigger signals when the multiple ignition permission signal is generated Is applied to the second to n-th discharge switches, and the second to n-th trigger signals are supplied to the second to n-th trigger signals when the multiple ignition prohibition signal is generated. 4. The ignition device for a capacitor discharge type internal combustion engine according to claim 2, further comprising: a multiple ignition control circuit for inhibiting application to the discharge switch. The control signal generation circuit generates the multiple ignition permission signal when rapid acceleration or sudden deceleration of the internal combustion engine is detected, and outputs the multiple ignition inhibition signal when rapid acceleration or sudden deceleration of the internal combustion engine is not detected. 5. The ignition device for a capacitor discharge internal combustion engine according to claim 4, wherein the ignition device is configured to generate an electric current. 5. The control signal generating circuit according to claim 4, wherein the control signal generation circuit is configured to generate the multiple ignition prohibition signal when the internal combustion engine is started, and to generate the multiple ignition permission signal after the internal combustion engine is started. Capacitor discharge type ignition device for internal combustion engines.

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