JP3293442B2 - Capacitor discharge type internal combustion engine ignition method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A capacitor discharge type internal combustion engine igniter includes an ignition coil, an ignition energy storage capacitor provided on a primary side of the ignition coil, and an electric connection between an ignition signal and an ignition signal to ignite the capacitor. A discharge switch for discharging through the primary coil of the coil, an ignition circuit including a spark plug connected to the secondary coil of the ignition coil and generating a spark when a high voltage for ignition is induced in the secondary coil, It comprises a charging power supply unit for charging the ignition energy storage capacitor, and an ignition signal generating unit for generating an ignition signal at an ignition position of the internal combustion engine.

[0003] As a charging method for the ignition energy storage capacitor, there are an AC method and a DC method. In the AC system, an ignition energy storage capacitor is charged with a rectified output using an exciter coil provided in a magnet generator attached to an internal combustion engine. In the DC method, an ignition energy storage capacitor is charged with a voltage obtained by boosting an output voltage (normally, 12 [V]) of a battery by a booster circuit using a chopper circuit.

[0004] A booster circuit used in the DC system has 100
A boost transformer that can respond to a high frequency of about [KHz] is required. Conventionally, since the size of the step-up transformer cannot be avoided, the charging power supply unit is mainly configured by using the AC method. However, recently, since a boosting transformer using a small ferrite core capable of responding to a high frequency has become available, a DC power supply has been often used to constitute a charging power supply unit. D
When the charging power supply unit is configured by adopting the C method, it is not necessary to provide an exciter coil having a large number of turns in the magnet generator, so that the size of the magnet generator can be reduced.

FIG. 3 shows an example of the configuration of a conventional capacitor discharge type internal combustion engine ignition device in which a charging power supply unit is formed by a DC system. In FIG. 1, reference numeral 1 denotes a capacitor discharge type ignition circuit, 2 denotes a charging power supply unit, and 3 denotes an ignition signal generation unit.

The charging power supply unit 2 includes a battery 2A, a booster circuit 2D including a booster transformer 2B and a chopper switch circuit 2C, an oscillator circuit 2E 'using a comparator, a differential control circuit 2F', and a differential circuit. 2G 'and a drive signal supply circuit 2H. The ignition signal generator 3 includes a signal coil 3 provided in a signal generator attached to the internal combustion engine.
A, an ignition position calculation device 3B, and an ignition signal output circuit 3C
It consists of

Further, reference numeral 4 'denotes a charging voltage detecting circuit for detecting a charging voltage of an ignition energy storage capacitor provided in the ignition circuit, and 5' denotes a charging voltage when the charging voltage of the ignition energy storage capacitor reaches a set value. A charge voltage limiting boosting operation stop circuit for stopping the boosting operation of the power supply unit, 6 'detects the discharge current of the ignition energy storage capacitor and detects that the magnitude of the discharge current of the capacitor is greater than or equal to the threshold value. The ignition boosting operation stop circuit stops the boosting operation of the booster circuit when the ignition is in operation.

In the ignition device shown in FIG. 3, an oscillation circuit 2E 'is driven and oscillated by an output voltage of a power supply circuit (not shown) using a battery 2A as a power supply, and the oscillation circuit 2E' outputs a pulse signal Vp. . The differential control circuit 2F 'includes a reference voltage Vr1 obtained by dividing the power supply voltage Vcc and a pulse signal Vp.
And a comparator CPo that compares
o indicates that when the pulse signal Vp becomes equal to or higher than a reference voltage Vr1 giving a predetermined threshold value, the output signal is set to a low level, and when the pulse signal Vp becomes lower than the reference voltage Vr1, the output signal is set to a high level. To level.

When the output signal of the comparator CPo changes to a high level, the differentiating circuit 2G 'charges the differentiating capacitor C1 through the resistor R7 with the output voltage Vcc of the power supply circuit (not shown). Since the transistor TR5 conducts for a predetermined time during which the charging current flows through the capacitor C1, a pulse signal (pulse signal falling from a high level to a low level) Vd having a predetermined time width is applied between the collector and the emitter of the transistor TR5. 'Is obtained. When the output pulse Vp of the oscillation circuit 2E 'exceeds the reference voltage Vr1 and the output signal of the comparator CPo goes low, the electric charge of the differential capacitor C1 is discharged through the output stage of the comparator CPo, the ground circuit, and the diode D3. By these operations, a driving pulse Vd 'having a fixed time width is output from the differentiating circuit 2G, and the driving pulse Vd' is inverted by the driving signal supply circuit 2H,
The signal is supplied to the drive signal input terminal of the chopper switch circuit 2C as the drive signal Vd.

The chopper switch circuit 2C includes an FET F1 connected in series to a primary coil of a step-up transformer,
An NPN transistor TR1 having a collector connected to the positive terminal of the battery, an emitter connected to the emitter of the transistor TR1, and a PNP transistor TR2 having a collector grounded with the source of the FET; a common connection point of the emitters of the transistors TR1 and TR2; A resistor R1 connected between the gate of the FET and a transistor TR
A drive signal Vd is provided to the bases of the transistors TR1 and TR2. In this example, the oscillation circuit 2E
, A differentiation control circuit 2F ′, a differentiation circuit 2G, and a drive signal supply circuit 2H, thereby forming a chopper switch circuit 2C.
And a chopper switch drive circuit for supplying a drive signal Vd to the switch.

The drive signal V is supplied to the chopper switch circuit 2C.
When d is given, the transistor TR2 is turned off only while the drive signal is being generated, so that a pulse-like drive signal Vg of a fixed time width is given to the gate of the FET F1 through the transistor TR1. This allows FE
TF1 becomes conductive and the primary coil W1 of the step-up transformer 2B
The primary current I1. When the drive signal Vd disappears, the transistor TR2 is turned on to stop supplying the drive signal to the FET F1, so that the FET F1 is turned off. The time width of the drive signal Vd (the time during which the primary current flows through the step-up transformer) is set so that the FET F1 is turned off immediately before the magnetic flux flowing through the core of the step-up transformer is saturated. When the FET F1 is cut off, the primary current is cut off, so that the magnetic flux flowing through the iron core of the step-up transformer suddenly becomes zero, and a high voltage (for example, 200 [V]) is applied to the secondary coil of the step-up transformer. Degree) is induced. This voltage is applied to the ignition circuit 1 through a rectifier circuit comprising a diode D1.
Given to.

The illustrated ignition circuit 1 includes an ignition coil IG,
An ignition energy storage capacitor Ci provided on the primary side of the ignition coil; a thyristor Si serving as a discharge switch for conducting when an ignition signal Vi is applied to discharge the charge of the capacitor Ci to the primary coil of the ignition coil; A resistor Ri connected between the gate and cathode of the thyristor Si
A diode Di connected to both ends of the primary coil of the ignition coil, and a spark plug P attached to the cylinder of the engine and connected to the secondary coil of the ignition coil. The voltage induced in the next coil is applied to the ignition energy storage capacitor Ci through the diode D1. Each time a voltage is induced in the secondary coil W2 of the step-up transformer, the capacitor Ci is connected to the secondary coil W2 → the diode D1 → the capacitor Ci → the diode Di and the primary coil → the secondary coil W2 of the ignition coil IG.
Is charged to the polarity shown in FIG.

The ignition signal generating section 3 is provided with a signal coil 3A provided in a signal generator attached to the engine, and an ignition position of the engine based on rotation angle information and speed information obtained from the output of the signal coil 3A. The ignition position signal Vip which falls from the high level to the low level at the calculated ignition position
And an ignition signal output circuit 3C for outputting the ignition signal Vi by turning on the transistor TR7 when the ignition position operation device 3B generates the ignition position signal Vip.

When the ignition signal output circuit 3C outputs the ignition signal Vi, the thyristor Si of the ignition circuit 1 conducts to discharge the electric charge of the capacitor Ci through the primary coil of the ignition coil IG. A large change in magnetic flux occurs, and this change in magnetic flux induces a high voltage for ignition in the secondary coil of the ignition coil IG. Since this high voltage is applied to the spark plug P, a spark is generated in the spark plug and the engine is ignited.

In the course of charging the ignition energy storage capacitor Ci, when the charging voltage of the capacitor Ci reaches a set value, the output voltage V4 of the charging voltage detection circuit 4 'becomes higher than the reference voltage Vr2. The output terminal of the comparator CP1 constituting the voltage limiting boosting operation stop circuit 5 'is set to the ground potential, and one end of the differential capacitor C1 of the differentiating circuit 2G is forcibly grounded. for that reason. The differentiating circuit 2G 'cannot generate the driving pulse Vd', and the FET of the chopper switch circuit 2C is kept off. Therefore, the booster circuit 2D stops its boosting operation and stops charging the ignition energy storage capacitor Ci. This prevents the charging voltage of the ignition energy storage capacitor Ci from becoming excessive. When the capacitor Ci discharges, the potential of the output terminal of the comparator CP1 becomes high level, and the operation of the differentiating circuit 2G 'is permitted.

When an ignition signal is given to the thyristor Si,
Is turned on, the discharge current of the capacitor Ci flowing from the anode to the cathode of the thyristor Si causes the voltage between the gate and the cathode of the thyristor to rise, and the comparator CP2 constituting the boosting operation stop circuit 6 'during the ignition operation
Gate-cathode voltage V of thyristor Si input to
Since gk is equal to or higher than the reference voltage Vr3, the output terminal of the comparator CP2 is at the ground potential, and one end of the differential capacitor C1 is grounded. As a result, the differentiating circuit 2G 'outputs the driving pulse Vd.
In order to stop the generation of ', the generation of the drive signal Vd is stopped, the FET of the chopper switch circuit 2C is kept in the cut-off state, and the booster circuit 2D stops the boosting operation. When the discharge of the ignition energy storage capacitor Ci is completed, the gate-cathode voltage Vgk of the thyristor Si becomes lower than the reference voltage Vr3, so that the potential of the output terminal of the comparator CP2 becomes high level, and the operation of the differentiation circuit 2G is stopped. Will be resumed. This ensures that the thyristor Si is turned off.

FIG. 4 shows voltage waveforms at various points of the ignition device of FIG. 3 with respect to the rotation angle θ of the engine. FIG. 4A shows signals Vs1 and Vs2 generated by the signal coil 3A. FIG. 4B shows the ignition signal V output from the ignition signal output circuit 3C.
i. The signals Vs1 and Vs2 are respectively generated at specific rotational angular positions, for example, the maximum advance position and the minimum advance position of the engine. The ignition position calculation device 3B obtains rotation angle information and rotation speed information of the engine from these signals, calculates an ignition position at each rotation speed, and generates an ignition position signal Vip when the calculated ignition position is detected. Output. The ignition signal output circuit 3C outputs the ignition signal Vi (FIG. 4B) when the ignition position signal Vip is generated.

FIG. 4C shows the waveform of the drive signal Vg applied to the gate of the FET F1. During the generation of the drive signal Vg, the FET F1 conducts and the primary current flows to the step-up transformer 2B. Flow. When the drive signal Vg becomes zero, the FET F1 is turned off, so that a voltage is induced in the secondary coil of the step-up transformer 2B. The frequency of the drive signal Vg is set to, for example, about 100 [KHz], and the ignition energy storage capacitor Ci is charged each time a voltage is induced on the secondary side of the step-up transformer. In a state where no charge is stored in the capacitor Ci (a state immediately after the ignition operation is performed), the charging current flowing through the capacitor Ci when the boosting transformer generates the secondary voltage is large, and the time required for the charging current to flow is long. However, as the charging of the capacitor Ci progresses, the charging current decreases, and the time during which the charging current flows decreases. Therefore, the load of the booster circuit 2D is largest when charging of the capacitor Ci is started (immediately after the ignition operation is performed), and gradually decreases as charging progresses.

[0019]

In the above ignition device,
Since the secondary voltage induced when the primary current of the step-up transformer is cut off is a pulsed voltage, it is not possible to charge the ignition energy storage capacitor to the voltage required for the ignition operation by one charge, The series of secondary voltages generated by the step-up transformer gradually charges the ignition energy storage capacitor. In this case, in order to charge the ignition energy storage capacitor to a predetermined voltage required for the ignition operation during one revolution of the engine, it is necessary to turn on and off the chopper switch of the booster circuit (in the above example, the oscillation circuit 2E '). Oscillation frequency) must be set to an appropriate value.

When the charging voltage of the ignition energy storage capacitor is low and the load of the boosting circuit is large, the charging current flows through the ignition energy storage capacitor for a long time, so that the on / off frequency of the chopper switch of the boosting circuit is set high. Then, a state occurs in which the chopper switch conducts while a part of the magnetic flux generated during the previous conduction of the switch remains, and the primary current becomes extremely easy to flow. Therefore, the primary current of the step-up transformer becomes considerably larger than when the load is small, and the power consumption on the primary side of the step-up transformer increases irrespective of the rotational speed of the engine, and the heat generated by the step-up transformer and the chopper switch is increased. Inevitably increase. Therefore, when the charging voltage of the ignition energy storage capacitor is low and the load of the booster circuit is large, it is preferable to set the on / off frequency of the chopper switch to be low.

When the charging voltage of the ignition energy storage capacitor is increased and the load of the booster circuit is reduced, the charging current flowing through the capacitor is small and the charging current flows for a short time. If the on / off frequency of the capacitor is set low, it takes a long time to make the charging voltage of the ignition energy storage capacitor reach a predetermined value, and the charging speed of the capacitor decreases. When the charging speed of the ignition energy storage capacitor is reduced, the ignition energy storage capacitor cannot be charged to a value necessary for obtaining sufficient ignition performance, and the ignition performance is reduced. Therefore, when the charging voltage of the ignition energy storage capacitor is high and the load on the booster circuit is small, it is preferable to set the on / off frequency of the chopper switch to be high.

However, in this type of conventional ignition device,
Since the on / off frequency of the chopper switch is constant, an appropriate frequency cannot be set for both a large load state and a small load state of the booster circuit.

That is, if the on / off frequency of the chopper switch is set high in accordance with the light load of the booster circuit, when the load of the booster circuit is heavy (from the initial charging to the first half of charging of the ignition energy storage capacitor), Since a state occurs in which the switch conducts while a part of the magnetic flux generated during the previous conduction of the switch remains in the iron core of the step-up transformer, the primary current of the step-up transformer increases,
The efficiency of the step-up circuit is deteriorated, and the heat generated by the step-up transformer and the switch for the chopper increases.

Further, if the ON / OFF frequency of the chopper switch is set low in accordance with the charging voltage of the ignition energy storage capacitor being low and the load of the booster circuit being large, the charging of the ignition energy storage capacitor proceeds and the booster circuit is charged. When the load is reduced, the charging speed of the ignition energy storage capacitor is reduced, so that the charging voltage of the ignition energy storage capacitor cannot reach a sufficient value, which causes a problem that the ignition performance is reduced.

In the conventional capacitor discharge type ignition device shown in FIG. 3, the constant time of the primary current flowing through the step-up transformer is kept constant by appropriately setting the constant of the differentiating circuit 2G '. However, when the primary transformer current supply time is constant, the amount of magnetic flux flowing through the iron core of the step-up transformer changes according to the battery voltage when the chopper switch circuit enters the cut-off state. The magnitude of the voltage induced in the secondary coil of the step-up transformer is affected by the battery voltage due to the single interruption of the voltage, and the voltage induced in the secondary coil of the step-up transformer decreases when the battery voltage decreases, and the ignition is performed. There is a problem that the energy storage capacitor cannot be charged to a sufficiently high voltage.

In particular, since a small and lightweight battery mounted on a small vehicle such as a motorcycle is often used, even if the battery is charged by the output of a generator attached to the internal combustion engine, a large battery is required. When a load is applied, the battery voltage may decrease. Further, in a race vehicle, a circuit for charging a battery may be omitted in order to reduce the weight, and the vehicle may travel without charging the battery.

As described above, when the battery voltage is unavoidable and the conventional ignition device shown in FIG. 3 is used, when the battery voltage drops, the charging voltage of the ignition energy storage capacitor is reduced. There is a problem that the ignition performance is reduced due to the decrease.

An object of the present invention is to improve the efficiency of a booster circuit by reducing power consumption in a booster transformer without lowering the charging speed of an ignition energy storage capacitor.
An object of the present invention is to provide a capacitor discharge type internal combustion engine ignition method capable of suppressing heat generation in a step-up transformer and a chopper switch and an ignition device for implementing the method.

[0029] Another object of the present invention, as the battery voltage is not one blocked by substantially change the voltage induced in the step-up transformer secondary coil of the chopper switch circuit even when reduced, ignition energy storage It is an object of the present invention to provide a method for igniting a capacitor-discharge-type internal combustion engine, which eliminates the possibility that the charging voltage of the capacitor becomes insufficient, and an ignition device for implementing the method.

[0030]

SUMMARY OF THE INVENTION In an ignition method according to the present invention, a step-up transformer in which an output voltage of a battery is applied to a primary coil, and a chopper switch circuit for turning on and off a primary current flowing through the primary coil of the step-up transformer. A voltage induced in a secondary coil of the step-up transformer is applied through a rectifier circuit; an ignition energy storage capacitor; and an ignition coil, which is turned on when an ignition signal is supplied to ignite the charge of the ignition energy storage capacitor. A discharge switch for discharging through the primary coil of the coil is provided, and a secondary current of the step-up transformer is detected to detect the secondary current.
When the primary current is detected to be less than a predetermined threshold , the chopper switch circuit is turned on to supply a primary current to the step-up transformer, and the primary current of the step-up transformer is detected and the primary current is set to a set value. When it is detected that the voltage has reached the voltage, the primary current is cut off to induce a voltage in the secondary coil of the step-up transformer. And the process of charging to the polarity of the polarity is repeatedly performed. And
An ignition signal is supplied to the discharge switch at the ignition position of the internal combustion engine to conduct the discharge switch, thereby discharging the charge of the ignition energy storage capacitor through the primary coil of the ignition coil, and igniting by discharging the ignition energy storage capacitor. The engine is ignited by applying a high voltage induced in the secondary coil of the coil to the spark plug to cause a spark in the spark plug.

It is preferable that the set value of the primary current is set to a value slightly smaller than the primary current value at which the magnetic flux of the step-up transformer is saturated.

As described above, the primary current of the step-up transformer is detected, and when it is detected that the primary current has reached the set value, the primary current is cut off, so that a voltage is applied to the secondary coil of the step-up transformer. , It is possible to make the cutoff value of the primary current constant regardless of the battery voltage, and to make the voltage induced in the secondary coil of the step-up transformer constant by one cutoff of the chopper switch circuit. It is possible to prevent the charging voltage of the ignition energy storage capacitor from becoming insufficient when the battery voltage drops.

As described above, the secondary current of the step-up transformer is detected, and when it is detected that the secondary current is less than the predetermined threshold value, the chopper switch circuit is turned on to allow the step-up transformer to operate. When the primary current is allowed to flow, the primary current does not flow when the secondary current is flowing through the boost transformer, that is, when the magnetic flux is flowing through the iron core of the boost transformer. It is possible to prevent the power consumption of the transformer from increasing and to increase the efficiency of the booster circuit, thereby preventing the heat generation of the booster transformer and the heat generation of the chopper switch circuit from increasing. .

Further, with the above configuration, the secondary current is
Since the primary current flows immediately after the voltage falls below the threshold value, as the load on the step-up transformer decreases (the charging current of the ignition energy storage capacitor advances and the time for the charging current to flow decreases), the chopper switch circuit The on / off frequency can be increased. Therefore, the charging rate of the ignition energy storage capacitor can be increased, and the voltage induced in the secondary coil of the step-up transformer can be kept constant regardless of the battery voltage. The charging capacitor can always be charged to a sufficiently high voltage to perform a satisfactory ignition operation.

In order to prevent the charging voltage of the ignition energy storage capacitor from becoming excessive, the process of supplying the primary current to the step-up transformer is performed only when the charging voltage of the ignition energy storage capacitor is less than the set value. It is preferred that this be done. In order to surely turn off the thyristor when the thyristor is used as the discharge switch, it is preferable that the step of supplying the primary current to the step-up transformer be performed after the discharge switch is turned off. That is, the process of supplying the primary current to the step-up transformer is performed by setting the secondary current of the step-up transformer to a predetermined value in a state where the discharge switch is shut off and the voltage between both ends of the ignition energy storage capacitor is less than the set value. It is preferable that the processing be performed when it is detected that the value has become smaller than the threshold value.

The igniter used to carry out the above-described ignition method includes a step-up transformer 2B in which an output voltage of a battery 2A is applied to a primary coil and a booster transformer 2B which conducts while a drive signal is being supplied, and is connected to the step-up transformer by the battery. Circuit 2 having a chopper switch circuit 2C for supplying a primary current to the circuit
And D, the secondary current of the step-up transformer 2B is flowing a primary current to the step-up transformer by conducting the chopper switch circuit 2C when it is detected is below a predetermined threshold value, the primary current of the step-up transformer is set When it is detected that the voltage has reached the value, the chopper switch circuit 2C is turned off to induce a voltage in the secondary coil of the booster transformer, and the chopper switch circuit 2C is driven in accordance with the primary current and the secondary current of the booster transformer. A chopper switch control circuit 2J for controlling the switch circuit 2C, an ignition coil IG, and an ignition energy storage capacitor Ci provided on the primary side of the ignition coil and charged to one polarity by the output voltage of the booster circuit 2D; ,
A discharge switch Si provided so as to conduct when an ignition signal is given at an ignition position of the internal combustion engine to discharge the electric charge of the capacitor Ci through the primary coil of the ignition coil.

The chopper switch control circuit 2J includes:
Detecting a secondary current in said secondary current Tokoro of the step-up transformer 2B
A chopper drive command signal generating circuit 2E for generating a chopper drive command signal when it is detected is below Jono threshold, the drive pulses Vd having a predetermined time width when the chopper drive command signal is generated ' , A drive signal supply circuit 2H for supplying a drive signal Vd to the chopper switch circuit 2C when a drive pulse is generated, a primary current for detecting a primary current of the step-up transformer 2B, and detecting the primary current. Command signal generation circuit 2K that generates a cut command signal when it is detected that the set value has reached a set value.
And a switch cutoff control circuit 2 for preventing a drive signal from being supplied to the chopper switch circuit when a cutoff command signal is generated and for setting the chopper switch circuit to a cutoff state.
And L.

The chopper drive command signal generating circuit 2E
The secondary current detection diode D2 inserted in the secondary circuit of the step-up transformer with the secondary current flowing through the secondary coil of the step-up transformer 2B flowing in the ignition energy storage capacitor flowing in the forward direction; A constant voltage power supply circuit 7 that outputs a substantially constant DC voltage with an output as an input
And a drive command signal generating transistor TR3 which is turned on when a base current is applied at the output of the transistor D3 to conduct and the base-emitter is reverse-biased due to a forward voltage drop generated across the charging current detecting diode D2. Can be configured.

The driving pulse generating circuit includes a differential capacitor C1 charged by the output of the constant voltage power supply circuit through the resistors R7a and R7b, and a transistor for generating a differential pulse which is rendered conductive by being supplied with a base current by the charging current flowing through the differential capacitor. A differential circuit 2G having a transistor TR5 for generating a drive pulse Vd 'between the collector and the emitter of the differential pulse generating transistor; and a differential capacitor for conducting when the drive command signal generating transistor TR3 is turned off. C1 is discharged, and while the driving command signal generating transistor TR3 is in the cut-off state, the conduction state is maintained to prevent the charging of the differential capacitor C1 and cut off when the driving command signal generating transistor TR3 is turned on. Switch circuit 2 for differential control that allows charging of differential capacitor C1 It can be constructed by providing and.

The shutoff command signal generating circuit 2K compares the voltage across the primary current detecting resistor R20 connected in series with the primary coil of the step-up transformer and the voltage across the primary current detecting resistor with a reference voltage. A comparator CP1 for generating a cutoff command signal when the voltage across the primary current detection resistor becomes higher than the reference voltage.

The switch cutoff control circuit 2L can be constituted by a cutoff control switch Pu1 which conducts when a cutoff command signal is generated and prevents the base current from being supplied to the differential pulse generating transistor TR5.

In order to prevent the charging voltage of the ignition energy storage capacitor from becoming excessive, the voltage across the both ends of the ignition energy storage capacitor Ci is detected, and the drive signal is output when the voltage across the capacitor exceeds a set value. It is preferable to further provide a boosting operation stopping circuit 5 for limiting the charging voltage, which stops the boosting operation of the boosting circuit by preventing the occurrence of the above.

When a thyristor is used as the discharge switch, in order to ensure that the discharge switch is turned off, the ignition drive which generates the switch drive stop command signal Va for a set time when the ignition signal is generated is generated. It is preferable to further include a stop command signal generating means and a boosting operation stop circuit during ignition operation 6 for stopping the boosting operation of the booster circuit 2D by preventing the generation of the drive signal while the switch drive stop command signal is being generated. . The set time is set slightly longer than the time required from the time when the discharging switch Si is turned on to the time when the discharging switch Si is turned off.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is an ignition circuit, 2 is a charging power supply unit, 3 is an ignition signal generation unit, 4 is a charging voltage detection circuit,
Reference numeral 5 is a charge voltage limiting boosting operation stop circuit, 6 is an ignition operation boosting operation stop circuit, and 7 is a constant voltage power supply circuit. Hereinafter, the configuration of each unit will be described.

The ignition circuit 1 conducts the ignition coil IG, the ignition energy storage capacitor Ci provided on the primary side of the ignition coil, and the ignition signal Vi, and conducts the electric charge of the capacitor Ci to the primary of the ignition coil. This is a well-known capacitor discharge type circuit including a thyristor Si serving as a discharge switch for discharging a coil and an ignition plug P attached to a cylinder of the engine and connected to a secondary coil of the ignition coil.

Although the specific configuration of the capacitor discharge type ignition circuit has various modifications, the configuration of the illustrated circuit will be described in further detail. In this example, one end of the primary coil L1 of the ignition coil IG is grounded. One end of an ignition energy storage capacitor Ci is connected to the other end of the primary coil. A thyristor Si is connected between the other end of the capacitor Ci and the ground with the cathode facing the ground, and a resistor Ri is connected between the gate and the cathode of the thyristor Si. Both ends of the primary coil L1 of the ignition coil IG are connected to a diode Di whose cathode is directed to the ground side. One end of a secondary coil L2 of the ignition coil IG is commonly connected to the other end of the primary coil L1, and the other end of the secondary coil L2 is connected to a non-ground terminal of a spark plug P attached to a cylinder of the engine. .

The charging power supply section 2 includes a battery 2A having a negative electrode grounded, a booster circuit 2D including a booster transformer 2B and a chopper switch circuit 2C, and a chopper switch control circuit 2J. The chopper switch control circuit 2J includes a chopper drive command signal generation circuit 2E, a differentiation control switch circuit 2F, a differentiation circuit 2G, a drive signal supply circuit 2H, a cutoff command signal generation circuit 2K, and a switch cutoff control circuit 2L. It consists of.

In this example, the voltage (normally 12 [V]) across the battery 2A is input to the constant voltage power circuit 7 through the power switch SW, and a substantially constant DC voltage Vcc obtained from the constant voltage power circuit 7 is obtained. Is applied to the power supply terminal of each part.

Although not shown, the battery 2A is charged through a predetermined charging circuit by the output of a charging coil provided in a magnet generator attached to the internal combustion engine.

The step-up transformer 2B is formed by winding a primary coil W1 and a secondary coil W2 around a ferrite core, and one end of the primary coil W1 is connected to a positive terminal of the battery 2A. The other end of the primary coil W1 is connected to the drain of an FET (field effect transistor) F1.
The source of F1 is grounded through a primary current detecting resistor R20. Df is a parasitic diode existing between the drain and source of the FET.

One end of a resistor R1 is connected to the gate of the FET F1, and the other end of the resistor R1 is connected to an NPN transistor TR1.
And the emitter of the PNP transistor TR2. The collector of the transistor TR1 is connected to the positive terminal of the battery 2A through the power switch SW, and the collector of the transistor TR2 is grounded. The bases of the transistors TR1 and TR2 are commonly connected, and a resistor R2 is connected between the common connection point of the bases of both transistors and the collector of the transistor TR1. Transistors TR1 and TR2 and resistor R
A drive circuit for driving the FET F1 is constituted by 1 and R2, and a chopper switch circuit 2C is constituted by the drive circuit and the FET F1. In the chopper switch circuit 2C, the common connection point of the bases of the transistors TR1 and TR2 is an input terminal of a drive signal, and the input terminal has a positive drive signal Vd (rising to a positive potential with respect to the ground). Is applied, the transistor TR2 is turned off, the transistor TR1 is turned on, and the drive signal Vg is applied from the battery 2A to the FET F1 through the switch SW, the collector and the emitter of the transistor TR1, and the resistor R1. It has become. The FET F1 conducts while the drive signal Vg is being supplied (while the drive signal Vd is being generated), and causes the primary current to flow to the step-up transformer 2B.

One end of the secondary coil W2 of the step-up transformer 2B is connected through a diode D1 to a connection point between the ignition energy storage capacitor Ci and the anode of the thyristor Si.

At the other end of the secondary coil W2 of the step-up transformer, a charging current detecting diode D2 having an anode grounded is provided.
The diode D2 is connected in series to the secondary coil W2, and the cathode of the diode D2 is connected to the base of a drive command signal generating transistor TR3 whose emitter is grounded. Resistors R3 and R4 are connected between the collector of the transistor TR3 and the output terminal of the constant voltage power supply circuit 7, and between the base of the transistor TR3 and the output terminal of the power supply circuit 7, respectively.
3, a resistor R5 is connected between the base grounds. In this example, a chopper drive command signal generating circuit 2 is composed of a diode D2, a transistor TR3, and resistors R3 to R5.
E is configured.

The collector of the transistor TR3 is connected to the base of the differential control transistor TR4, and the resistor R6 is connected between the base and the emitter of the transistor TR4. In this example, the transistor TR4 and the resistor R6 constitute a differential control switch circuit 2F.

The collector of the differential control transistor TR4 is connected to one end of a differential capacitor C1, and the other end of the capacitor C1 is connected through a resistor R7b to the base of a differential pulse generating transistor TR5 whose emitter is grounded. . Between the base and the emitter of the transistor TR5, a diode D3 having an anode facing the ground and a resistor R15
Are connected in parallel, and a resistor R7a is connected between one end of the differential capacitor C1 and the output terminal of the power supply circuit 7.
In this example, a differential capacitor C1, a differential pulse generating transistor TR5, a diode D3, and resistors R7a to
R7b and R15 form a differentiating circuit 2G.

The drive signal supply circuit 2H includes an NPN transistor TR6 whose emitter is grounded, and a transistor TR6.
6 comprises a resistor R8 connected between the base of the power supply circuit 7 and the output terminal of the power supply circuit 7, and a resistor R9 connected between the base and the emitter of the transistor TR6.
A transistor TR is connected to the base and the emitter of R6, respectively.
5 is connected to the collector and the emitter of
The collector of R6 is the drive signal input terminal of the chopper switch circuit 2C (the bases of the transistors TR1 and TR2).
It is connected to the.

In this example, the differential control switch circuit 2F
And a differentiating circuit 2G constitute a driving pulse generating circuit which is triggered when a chopper driving command signal is generated and generates a pulse having a predetermined time width as a driving pulse Vd '. The drive signal supply circuit 2H inverts the polarity of the drive pulse Vd 'and supplies it as a drive signal Vd to the drive signal input terminal of the chopper switch circuit 2C.

The voltage V20 across the primary current detecting resistor R20
Is input to the inverting input terminal of the comparison circuit CP1 through the resistor R21. The non-inverting input terminal of the comparison circuit CP1
A reference voltage Vr1 obtained by dividing the output voltage Vcc of the constant voltage power supply circuit 7 by a voltage dividing circuit composed of a series circuit of resistors R22 and R23 is input. The output terminal of the comparison circuit CP1 is connected to the gate of a programmable unijunction transistor (PUT) Pu1 whose cathode is grounded.
The anode of the UT is connected to the connection point between the differential capacitor C1 and the resistor R7b. A resistor R24 is connected between the anode and the gate of PUT Pu1.

In this example, a primary current detecting resistor R20,
A shutoff command signal generating circuit for detecting the primary current of the step-up transformer 2B by the resistors R21 to R23 and the comparing circuit CP1 and generating an interrupt command signal Voff when it is detected that the primary current has reached a set value. 2K is configured. Further, the cutoff command signal Voff is generated by the PUT Pu1 and the resistor R24.
When the drive signal V is supplied to the chopper switch circuit when
The switch cutoff control circuit 2L is configured to block the chopper switch circuit from being supplied and to shut off the chopper switch circuit.

The ignition signal generator 3 includes a signal coil 3A,
It comprises an ignition position calculation device 3B for calculating the ignition position of the internal combustion engine by using the output of the signal coil 3A as an input, and an ignition signal output circuit 3C.

The signal coil 3A is provided on a signal generator attached to the engine, and as shown in FIG. 2A, the first signal is provided at the maximum advance position and the minimum advance position of the engine, respectively. Vs1 and a second signal Vs2. The ignition position calculator 3B calculates the ignition position at each rotation speed using the rotation angle information obtained from the signals Vs1 and Vs2 and the rotation speed information, and calculates the ignition position signal V based on the calculated ignition position.
Output ip. The ignition position signal Vip takes an appropriate form according to the configuration of the ignition signal output circuit 3C. In the illustrated example, the ignition position signal Vip is a signal that falls from a high level to a low level (ground potential) at the ignition position.

As the ignition position calculating device 3B, an analog type that calculates an ignition position by analog calculation, a C
A digital type that calculates an ignition position using a PU is known. In the present invention, any type of ignition position calculation device may be used, but in the illustrated example, the ignition position calculation device 3B comprises a CPU.

The ignition signal output circuit 3C has a PNP transistor TR7 having an emitter connected to the output terminal of the constant voltage power supply circuit 7, a base connected to the output terminal of the ignition position calculation device 3B, and one end connected to the collector of the transistor TR7. The resistor R11 is connected to a diode D4 having an anode connected to the other end of the resistor R11. The cathode of the diode D4 serves as an ignition signal output terminal for the gate of the thyristor Si of the ignition circuit 1 (ignition signal input terminal of the ignition circuit). )It is connected to the.

In the ignition signal output circuit 3C, when the ignition position signal Vip is given, the transistor TR7
And the ignition signal Vi passes between the emitter and collector of the transistor TR7, the resistor R11 and the diode D4.
[FIG. 2 (B)] is output. The rising position of the ignition signal Vi is the ignition position of the engine.

One end of the charging voltage detection circuit 4 is connected to a connection point between the connection point between the ignition energy storage capacitor Ci and the anode of the thyristor Si and the series connection of the resistors R12 and R13 and the connection point between the resistors R12 and R13. Connected resistor R14
A capacitor Ci is connected between the other end of the resistor R14 and the ground.
And an output voltage V4 corresponding to the charging voltage (terminal voltage of the capacitor Ci).

The charge voltage limiting step-up operation stop circuit 5 comprises a series circuit of resistors R30 and R31 connected between the output terminals of the constant voltage power supply circuit 7, and divides the power supply voltage Vcc to output the reference voltage Vr2. A reference voltage generating circuit 5A, a comparison circuit CP2 in which the output voltage V4 and the reference voltage Vr2 of the charging voltage detection circuit 4 are input to a non-inverting input terminal and an inverting input terminal, respectively, an output terminal of the comparing circuit CP2 and a constant voltage power supply. A resistor R32 connected between the output terminal of the circuit 7 and an NPN transistor TR8 whose base is connected to the output terminal of the comparison circuit CP2 via a resistor R33 and whose emitter is grounded.
And a resistor R34 connected between the base of the transistor TR8 and the ground. The collector of the transistor TR8 is connected to the connection point between the differential capacitor C1 and the resistor R7a.

The ignition operation boosting operation stop circuit 6 includes an NPN transistor TR9 having a collector connected to a connection point of the differential capacitor C1 and the resistor R7a and having an emitter grounded;
A resistor R35 connected between the base and the emitter of the transistor TR9, a resistor R36 having one end connected to the base of the transistor TR9, and a resistor connected between the other end of the resistor R36 and the output terminal of the constant voltage power supply circuit 7. The base of the transistor TR9 is connected to the output port of the CPU constituting the ignition position calculating device 3. The CPU constituting the ignition position calculation device 3 realizes an ignition operation drive stop command signal generating means for generating a switch drive stop command signal Va for a set time when an ignition signal is generated. The set time (signal width of switch drive stop command signal Va)
Is set slightly longer than the time required from the time when the thyristor Si constituting the discharging switch becomes conductive to the time when the thyristor Si is turned off. The switch drive stop command signal Va output from the CPU is supplied to the transistor TR9 through the resistor R37.
Is entered in the base.

When the engine is started, the CPU is initialized.
A switch drive stop command signal Va is generated from the PU.

Next, the operation of the above-described ignition device will be described together with the ignition method according to the present invention. In the ignition device of FIG.
With the power switch SW open, the differentiation capacitor C
Assume that the charge of 1 is zero.

When the power switch SW is open,
The transistors TR1 to TR6 are in the cut-off state, and the FET
Since F1 is open, the step-up transformer 2B stops generating voltage.

When the power switch SW is turned on, the constant voltage power circuit 7 generates the voltage Vcc, and the voltage Vcc is applied to the chopper drive command signal generation circuit 2E. At this time, no current flows through the secondary coil W2 of the step-up transformer, and no forward voltage drop occurs across the diode D2, so that the transistor TR3 is turned on and the transistor T3 is turned on.
R4 is off. At this time, the power supply voltage Vcc is
Since the voltage is applied between the base and the emitter of the transistor TR5 through a series circuit of the differential capacitor 7a, the differential capacitor C1 and the resistor R7b, the charging current flowing from the constant voltage power supply circuit 7 to the differential capacitor C1 through the resistors R7a and R7b
R5 flows as a base current. Since the transistor TR5 conducts only while the charging current of the differential capacitor C1 is flowing, the drive pulse Vd that falls from a high potential to almost zero potential between the collector and the emitter of the transistor TR5.
'Occurs. Since the transistor TR6 is turned off only while the drive pulse Vd 'is being generated (while the transistor TR5 is conducting), it corresponds to an inversion of the drive pulse Vd' between the collector and the emitter of the transistor TR6. A drive signal Vd is generated. Since the transistor TR2 is turned off while the drive signal Vd is being generated (while the transistor TR6 is turned off), FIG.
As shown in (C), a drive signal Vg is supplied to the FET F1 through the collector and the emitter of the transistor TR1 and the resistor R1. As a result, the FET F1 becomes conductive, and a primary current flows through the step-up transformer 2B.

When the primary current of the step-up transformer 2B reaches the set value, the voltage across the primary current detecting resistor R20 reaches the set value, and the voltage V20 input to the inverting input terminal of the comparison circuit CP1 becomes the reference voltage Vr1. The comparison circuit CP1
Of the output terminal becomes the ground potential. This allows PUT
Pu1 conducts. When the PUT is turned on, the base current flowing to the transistor TR5 through the differential capacitor C1 and the resistor R7b is bypassed from the transistor TR5, so that the transistor TR5 is turned off. When the transistor TR5 is turned off, the transistor TR6 is turned on (the drive signal Vd disappears), so that the transistor TR2 is turned on and the drive signal Vg of the FET F1 disappears.

In the illustrated example, the magnitude of the primary current flowing through the step-up transformer 2B when the FET F1 of the chopper switch circuit is in the cut-off state causes the magnetic flux flowing through the core of the transformer 2B to be close to the saturation value. It is preferable to set the set value of the primary current so as to make the current value (not the saturation value).

The pulse width (time width) of the drive signal Vd supplied from the differentiating circuit 2G to the chopper switch circuit 2C through the drive signal supply circuit 2H is from the time when the primary current starts flowing through the boosting transformer to the time when the set value is reached. Is set to a time longer than the time. The pulse width of the drive signal Vd can be appropriately set by adjusting a time constant determined by the resistance values of the resistors R7a and R7b of the differentiating circuit 2G and the capacitance of the capacitor C1.

When the drive signal Vd disappears, the FET F1
Since the supply of the drive signal to the FET is stopped, the FET is turned off, and the primary current of the step-up transformer 2B is cut off.
As a result, a high voltage is induced in the secondary coil W2 of the step-up transformer 2B, and this voltage is applied to the ignition circuit 1 through the diode D1. At this time, the secondary coil W2 → the diode D1 → the ignition energy storage capacitor Ci → the diode Di and the primary coil L1 of the ignition coil → the diode D
2 → A charging current flows through the ignition energy storage capacitor Ci through the path of the secondary coil W2, and the capacitor Ci is charged to the polarity shown in the figure.

When the charging current of the ignition energy storage capacitor Ci is flowing, a forward voltage drop (about 0.6 volt at maximum) Vak is applied across the charging current detecting diode D2 as shown in FIG. Occurs. This voltage drop causes a reverse bias between the base and the emitter of the transistor TR3, so that the transistor TR3 is turned off and the transistor TR4 is turned on. Transistor TR
4 conducts, the differential capacitor C1 → transistor T
R4 collector-emitter → diode D3 → resistor R7b
→ The charge of the differential capacitor C1 is discharged through the path of the differential capacitor C1. The charging current flowing from the secondary coil W2 of the step-up transformer to the ignition energy storage capacitor Ci becomes less than a predetermined threshold value (substantially becomes zero), and the forward voltage drop across the diode D2 becomes less than a predetermined level. Then, the transistor TR3 is turned on, and the transistor TR4 is turned off. At the same time as the transistor TR4 is turned off, a charging current flows to the differential capacitor C1. Therefore, a driving pulse Vd 'is generated from the differentiating circuit 2G, and the driving signal Vd is supplied from the driving signal supply circuit 2H to the chopper switch circuit 2C. When the drive signal Vd is generated, the drive signal Vg is applied to the FET F1 to make the FET conductive, so that a primary current flows through the step-up transformer 2B. When the primary current reaches the set value and the drive signal V
When d disappears, the FET is cut off, the primary current of the step-up transformer is cut off, and the secondary coil W2 of the transformer is turned off.
Voltage is induced at

Thereafter, the same operation is repeated, and every time a voltage is induced in the secondary coil of the step-up transformer 2B, a charging current flows through the ignition energy storage capacitor Ci.
(F), as shown in FIG.
The voltage across i rises gradually.

As the charging of the capacitor Ci progresses, the time for the charging current to flow through the capacitor Ci decreases, and as shown in FIG. 2C, the drive signal Vg applied to the gate of the FET F1 The interval of occurrence becomes shorter. Accordingly, the charging interval of the ignition energy storage capacitor Ci becomes shorter as the charging of the capacitor progresses, and the voltage (charging voltage) V across the capacitor Ci is reduced.
ci rises as shown in FIG.

When the charging voltage Vci of the ignition energy storage capacitor Ci reaches the limit value Vcim, the output V4 of the charging voltage detecting circuit 4 exceeds the reference voltage Vr2.
The potential of the output terminal of P2 becomes high. As a result, the transistor TR8 becomes conductive and the differential capacitor C
One end of 1 is kept almost at the ground potential. Therefore, the differentiation circuit 2G
Stops generating the pulse signal Vd ', and the boosting operation of the booster circuit 2D stops. As a result, charging of the ignition energy storage capacitor Ci is stopped, and the charging voltage of the capacitor Ci is prevented from exceeding the limit value Vcim.

The ignition position calculating device 3 determines the ignition position of the internal combustion engine.
Generates an ignition position signal Vip, the ignition signal output circuit 3
C outputs an ignition signal Vi. Since this ignition signal is given to the thyristor Si, the thyristor Si conducts and discharges the electric charge of the capacitor Ci through the primary coil of the ignition coil IG. As a result, a high voltage for ignition is generated in the secondary coil of the ignition coil IG, a spark is generated in the ignition plug P, and the engine is ignited.

The ignition position calculation device 3 calculates the ignition position signal Vi
Is generated, a high-level switch drive stop command signal Va that is maintained for a set time is generated. While the switch drive stop command signal Va is being generated, the transistor T
Since R9 conducts, one end of the differentiating capacitor C1 is kept at the ground potential to prevent the differentiating circuit from generating the driving pulse Vd '. Since the signal width (set time) of the switch drive stop command signal Va is set slightly longer than the time required from the time when the thyristor Si turns on to the time when the thyristor Si turns off, the voltage is increased until the thyristor Si turns off. It is possible to prevent the circuit 2D from outputting a voltage and to reliably turn off the thyristor. When the switch drive stop command signal Va disappears, the transistor TR9 is turned off, so that the differentiating circuit 2G outputs the drive pulse Vd ', and the boosting circuit 2 starts the boosting operation.

In the above ignition device, the power switch S
If the differential capacitor C1 is in a charged state when W is closed, the differentiating circuit 2G does not generate the driving pulse Vd ', and the boosting circuit 2D does not perform the boosting operation. If the step-up operation is not performed, no current flows through the secondary coil W2 of the step-up transformer, so that the transistor TR3 keeps on and the transistor TR4 keeps off. When such a state occurs, the boosting operation cannot be started, and the ignition operation cannot be started. Further, even when the contact resistance of the power switch SW is turned on and the power supply voltage Vcc gradually rises when the power switch SW is turned on, the differentiating circuit 2G does not generate the drive pulse Vd '. Occurs.

As in the above-described example, the boosting operation stop circuit 6 during the ignition operation is provided, and the C
If the transistor TR9 is turned on when the PU is initialized or an ignition signal is generated, the differential capacitor C1 is forcibly discharged, and when the switch drive stop command signal Va disappears, the differential operation of the differential circuit 2G is started. Since the drive pulse Vd 'can be reliably generated after the ignition signal is generated once at the time of starting the engine, it is possible to eliminate the possibility that the engine will fail to start.

In order to prevent charges from remaining on the differential capacitor C1 when the engine is stopped, a reset switch is provided which is closed in conjunction with the power switch SW when the power switch SW is opened. It is also possible to adopt a configuration in which the differential capacitor is discharged by connecting it directly between one end of C1 and ground or via a current limiting element.

As described above, in the ignition method of the present invention, the step-up transformer 2B in which the output voltage of the battery 2A is applied to the primary coil W1, and the chopper switch for turning on and off the primary current flowing through the primary coil of the step-up transformer A circuit 2C, an ignition energy storage capacitor Ci to which a voltage induced in the secondary coil W2 of the step-up transformer 2B is applied through a rectifier circuit (the diode D1 in the above example);
An ignition coil IG and a discharge switch (thyristor Si in the above example) that conducts when an ignition signal Vi is supplied and discharges the charge of the ignition energy storage capacitor Ci through the primary coil L1 of the ignition coil are provided. Every
When the secondary current of the step-up transformer 2B is detected and it is detected that the secondary current is zero or less than a predetermined threshold value, the chopper switch circuit 2C is turned on to supply the primary current to the step-up transformer 2B. Process, detecting the primary current of the step-up transformer 2B and, when it is detected that the primary current has reached the set value, interrupting the primary current to induce a voltage in the secondary coil of the step-up transformer. And charging the ignition energy storage capacitor Ci to one polarity with a voltage induced in the secondary coil of the step-up transformer.

Then, at the ignition position of the internal combustion engine, an ignition signal Vi is given to the discharge switch Si to make the discharge switch conductive so that the ignition energy storage capacitor Ci is obtained.
Is discharged through the primary coil L1 of the ignition coil IG, and a high voltage induced in the secondary coil of the ignition coil by the discharge of the ignition energy storage capacitor Ci is applied to the ignition plug P to generate a spark in the ignition plug. To ignite the engine.

As described above, the primary current of the step-up transformer 2B is detected, and when it is detected that the primary current has reached the set value, the primary current is cut off, so that the secondary coil of the step-up transformer is connected. When the voltage is induced, the cutoff value of the primary current can be made constant regardless of the battery voltage, and the voltage induced in the secondary coil of the step-up transformer by one cutoff of the chopper switch can be made constant. It is possible to prevent the charging voltage of the ignition energy storage capacitor from becoming insufficient when the battery voltage drops.

As described above, when the secondary current of the step-up transformer 2B is detected and it is detected that the secondary current is less than the predetermined threshold, the chopper switch circuit 2C
When the primary current flows through the step-up transformer 2B, the primary current does not flow when the secondary current flows through the step-up transformer, that is, when the magnetic flux flows through the iron core of the step-up transformer. To prevent the power consumption of the transformer from increasing due to the increase of the primary current, thereby increasing the efficiency of the booster circuit, increasing the heat generation of the booster transformer and increasing the heat generation in the chopper switch circuit 2C. Can be prevented.

With the above configuration, the secondary current is
Since the primary current flows immediately after the voltage drops below the threshold ,
As the load of the step-up transformer decreases (the charging current of the ignition energy storage capacitor advances and the time for the charging current to flow decreases), the on / off frequency of the chopper switch can be increased. Therefore, the charging rate of the ignition energy storage capacitor can be increased, and the voltage induced in the secondary coil of the step-up transformer can be kept constant regardless of the battery voltage. The charging capacitor can always be charged to a sufficiently high voltage to perform a satisfactory ignition operation.

In the above example, the drive signal Vd is generated by using the differentiating circuit 2G. However, in the present invention, the secondary current (or the capacitor C) of the step-up transformer 2B is generated.
It is sufficient that a pulse having a fixed time width is generated as a drive signal when the (i.sup.i charging current) becomes less than the threshold value, and the configuration of the circuit for generating the pulse is not limited to the above example.
For example, a configuration in which a drive pulse is generated by triggering a monostable multivibrator when the secondary current of the step-up transformer 2B becomes less than the threshold value and the chopper drive command signal generation circuit 2E generates a chopper drive command signal. Can also be taken.

In the above example, the chopper switch circuit 2
In C, the FET is configured as a main switch element (a switch element for turning on and off a primary current of a step-up transformer).
Needless to say, the chopper switch circuit can be configured by using another switch element capable of on / off control such as a transistor as a main switch element.

In the above example, the ignition position is calculated using the ignition position calculation device. However, a capacitor discharge type ignition device in which an ignition signal is directly supplied to an ignition circuit by a signal generated by a signal coil is also used. The present invention can be applied.

In the above example, the capacitor Ci for storing the ignition energy of the ignition circuit 1 is connected in series to the primary coil of the ignition coil. However, a well-known configuration in which the positions of the capacitor Ci and the thyristor Si are interchanged. The present invention can also be applied to a case where the ignition circuit is used.

In the above example, the thyristor Si is used as the discharge switch.
Other switch elements such as ET can also be used.

[0096]

As described above, according to the present invention, the primary current of the step-up transformer is detected, and when it is detected that the primary current has reached the set value, the primary current is cut off to thereby increase the voltage. Since the voltage is induced in the secondary coil of the transformer, the cutoff value of the primary current is kept constant regardless of the battery voltage, and the cutoff of the chopper switch is induced once in the secondary coil of the step-up transformer. The voltage can be kept constant.

Therefore, it is possible to prevent the charging voltage of the ignition energy storage capacitor from becoming insufficient when the battery voltage drops.

Further, according to the present invention, the secondary current of the step-up transformer is detected, and when it is detected that the secondary current is less than the predetermined threshold value, the chopper switch circuit is turned on to turn on the step-up transformer. So that the primary current flows
When a secondary current flows through the step-up transformer and a magnetic flux flows through the core of the transformer, the primary current does not flow. For this reason, it is possible to prevent the primary current of the step-up transformer from increasing and the power consumption of the step-up transformer from increasing, thereby increasing the efficiency of the step-up circuit. An increase in heat generation can be prevented.

Further, according to the present invention, since the primary current flows immediately after the secondary current becomes less than the threshold value, the on / off frequency of the chopper switch is reduced as the load on the step-up transformer decreases. Can be higher. Therefore,
The charge rate of the ignition energy storage capacitor can be increased, and the voltage induced in the secondary coil of the step-up transformer can be kept constant regardless of the battery voltage. Can always be charged to a sufficiently high voltage to perform a satisfactory ignition operation.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration example of an ignition device for performing an ignition method according to the present invention.

FIG. 2 is a waveform diagram showing voltage waveforms at various parts in FIG.

FIG. 3 is a circuit diagram showing a configuration of a conventional ignition device.

FIG. 4 is a waveform diagram showing voltage waveforms at various parts in FIG.

[Explanation of symbols]

 Reference Signs List 1 ignition circuit 2 charging power supply unit 2A battery 2B step-up transformer 2C chopper switch circuit 2D step-up circuit 2E chopper drive command signal generation circuit 2F differentiation control switch circuit 2G differentiation circuit 2H drive signal supply circuit 3 ignition signal generation unit 4 charging voltage Detection circuit 5 Boost operation stop circuit for charging voltage limitation 6 Boost operation stop circuit at ignition operation

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02P 3/08

Claims (8)

(57) [Claims] 1. A step-up transformer for applying an output voltage of a battery to a primary coil, a chopper switch circuit for turning on and off a primary current flowing through the primary coil of the step-up transformer, and a voltage induced in a secondary coil of the step-up transformer An ignition energy storage capacitor applied through a rectifier circuit, an ignition coil, and a discharge switch that conducts when an ignition signal is supplied and discharges the charge of the ignition energy storage capacitor through the primary coil of the ignition coil. the may be provided, the booster transformer to detect the secondary current the secondary current is Tokoro
A step of conducting the primary current to the step-up transformer by conducting the chopper switch circuit when it is detected that the primary current is less than a predetermined threshold value , and a step of detecting the primary current of the step-up transformer to set the primary current. When it is detected that the voltage has reached the value, the primary current is cut off to induce a voltage in the secondary coil of the step-up transformer and the voltage induced in the secondary coil of the step-up transformer is used as the ignition energy storage capacitor. Is repeatedly performed, and an ignition signal is supplied to the discharge switch at the ignition position of the internal combustion engine to make the discharge switch conductive, thereby charging the charge of the ignition energy storage capacitor with the ignition coil. High voltage induced in the secondary coil of the ignition coil by the discharge of the ignition energy storage capacitor. Capacitor discharge engine ignition method characterized by igniting the engine by generating a spark in the ignition plug by applying a grayed. 2. A step-up transformer for applying an output voltage of a battery to a primary coil, a chopper switch circuit for turning on and off a primary current flowing through the primary coil of the step-up transformer, and a voltage induced in a secondary coil of the step-up transformer An ignition energy storage capacitor applied through a rectifier circuit, an ignition coil, and a discharge switch that conducts when an ignition signal is supplied and discharges the charge of the ignition energy storage capacitor through the primary coil of the ignition coil. In the state where the discharge switch is shut off and the voltage between both ends of the ignition energy storage capacitor is less than a set value, the secondary current of the step-up transformer falls below a predetermined threshold value. When it is detected that the voltage is full, the chopper switch circuit is turned on to supply a primary current to the step-up transformer. And detecting the primary current of the step-up transformer to cut off the primary current when it is detected that the primary current has reached a set value, thereby inducing a voltage in the secondary coil of the step-up transformer. And charging the ignition energy storage capacitor to one polarity with a voltage induced in the secondary coil of the step-up transformer, and applying an ignition signal to the discharge switch at the ignition position of the internal combustion engine. The electric charge of the ignition energy storage capacitor is discharged through the primary coil of the ignition coil by conducting the discharge switch, and the high voltage induced in the secondary coil of the ignition coil by the discharge of the ignition energy storage capacitor is applied to the ignition plug. And igniting the engine by applying a spark to the spark plug to apply the spark to the internal combustion engine. Law. 3. A step-up transformer (2B) in which an output voltage of a battery (2A) is applied to a primary coil, and a chopper switch that conducts while a drive signal is being supplied and flows a primary current from the battery to the step-up transformer. A booster circuit (2D) having a circuit (2C); and the chopper switch circuit when a secondary current of the booster transformer (2B) is detected to be less than a predetermined threshold value. (2C) is turned on, a primary current is supplied to the step-up transformer, and when it is detected that the primary current of the step-up transformer has reached a set value, the chopper switch circuit (2C) is turned off and the step-up is performed. Chopper switch control for controlling the chopper switch circuit (2C) according to a primary current and a secondary current of the step-up transformer so as to induce a voltage in a secondary coil of the transformer. Circuit (2
J), an ignition coil (IG), and the booster circuit (2) provided on the primary side of the ignition coil.
An ignition energy storage capacitor (Ci) charged to one polarity with the output voltage of D), and conducting when an ignition signal is given at an ignition position of the internal combustion engine to conduct the charge of the capacitor (Ci) to an ignition coil; And a discharge switch (Si) provided to discharge through the primary coil of the internal combustion engine. 4. An output voltage of a battery (2A) is a primary coil.
Transformer (2B) applied to the
While the battery is in operation,
And a chopper switch circuit (2C) for supplying a primary current to
And a secondary current of the step-up transformer (2B) having a predetermined threshold value.
When it is detected that the value is less than
Switch circuit (2C) to conduct the primary voltage to the step-up transformer.
A current flows, and the primary current of the step-up transformer reaches a set value.
When the chopper switch is detected,
Road (2C) in a cut-off state and the secondary coil of the step-up transformer
Primary voltage of the step-up transformer so as to induce voltage
Switch circuit for the chopper according to current and secondary current
Chopper switch control circuit (2C)
J), an ignition coil (IG), and the booster circuit (2
D) Ignition energy charged to one polarity with the output voltage
Conduction when an ignition signal is given at the ignition position of the internal combustion engine with the storage capacitor (Ci)
To charge the capacitor (Ci) to the primary of the ignition coil.
Discharge switch provided to discharge through the coil
Tsu; and a switch (Si), the chopper switch control circuit (2J), said secondary detecting the secondary current of the step-up transformer (2B)
A chopper drive command signal generating circuit (2E) for generating a chopper drive command signal when the current is detected to be less than a predetermined threshold value; and a predetermined time width when the chopper drive command signal is generated. A drive pulse generation circuit (2F, 2G) for generating a drive pulse (Vd '), and a drive signal supply circuit (2D) for supplying a drive signal (Vd) to the chopper switch circuit (2C) when the drive pulse is generated. 2H) and a shutoff command signal generating circuit (2) that detects a primary current of the step-up transformer (2B) and generates a shutoff command signal (Voff) when it is detected that the primary current has reached a set value.
K) a switch cutoff control circuit (2L) for preventing a drive signal from being supplied to the chopper switch circuit when the cutoff command signal (Voff) is generated, and for turning the chopper switch circuit into a cutoff state. A capacitor discharge type internal combustion engine ignition device comprising: 5. The chopper drive command signal generating circuit (2)
E) a secondary current detecting secondary current inserted in the secondary circuit of the step-up transformer in a direction in which a secondary current flowing through the secondary coil of the step-up transformer (2B) flows through the capacitor for storing ignition energy in a forward direction; A diode (D2),
The base current is applied to the output of the constant voltage power supply circuit (7), which outputs a substantially constant DC voltage with the output of the battery (2A) as an input, and conducts, and occurs at both ends of the charging current detection diode (D2). A drive command signal generating transistor (TR3) which is reverse-biased between the base and emitter by a forward voltage drop to be in a cut-off state, wherein the drive pulse generating circuit includes resistors (R7a, R7b) provided by the output of the constant voltage power supply circuit. ), And a differential pulse generating transistor (TR5), which is rendered conductive by being supplied with a base current by a charging current flowing through the differential capacitor, between the collector and the emitter of the differential pulse generating transistor. , A differentiating circuit (2G) for generating the drive pulse (Vd '), and the drive command signal generating transistor (TR3). ) Is turned off to conduct and discharge the differential capacitor (C1), and to generate the drive command signal generating transistor (TR).
3) While the conduction state is maintained, the conduction state is maintained and the charging of the differential capacitor (C1) is prevented, and when the drive command signal generating transistor (TR3) is brought into the conduction state, the state is cut off and the differentiation is performed. 5. A capacitor discharge type internal combustion engine ignition device according to claim 4, further comprising a differential control switch circuit (2F) for permitting charging of the capacitor (C1). 6. The shutoff command signal generation circuit (2K)
A primary current detecting resistor (R20) connected in series to the primary coil of the step-up transformer, and comparing the voltage across the primary current detecting resistor with a reference voltage to determine the voltage across the primary current detecting resistor. And a comparator circuit (CP1) for generating the shut-off command signal when the signal becomes higher than a reference voltage. The switch cut-off control circuit (2L) conducts when the cut-off command signal is generated to generate the differential signal. 6. The capacitor discharge type internal combustion engine ignition device according to claim 5, further comprising a cut-off control switch (Pu1) for preventing a base current from being supplied to the pulse generating transistor (TR5). 7. The ignition energy storage capacitor (C)
i) detecting the voltage across both ends of the capacitor, and, when the voltage across the capacitor exceeds a set value, prevents the generation of the drive signal and stops the boosting operation of the boosting circuit (a boosting operation stop circuit for charging voltage limitation) The ignition device for a capacitor discharge internal combustion engine according to claim 4 , wherein 5) is further provided. 8. An ignition drive stop command signal generating means for generating a switch drive stop command signal (Va) for a set time when the ignition signal is generated, and the switch drive stop command signal is generated. An ignition boosting operation stop circuit (6) for stopping the boosting operation of the boosting circuit (2D) by preventing generation of the drive signal during the operation, wherein the discharging switch (Si) is turned on for the set time. 8. The capacitor discharge type internal combustion engine ignition device according to claim 4 , wherein the time is set to be slightly longer than a time required until the shutdown state is established.