JPH10184512A - Internal combustion engine ignition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine ignition device of a capacitor discharging type which can obtain ignition spark with long electric discharging time. SOLUTION: Provided on a primary side of an ignition coil 3 are an ignition energy storing capacitor C1 charged by an output of an exciter coil W1 arranged inside a magnetic generator 1 rotated synchronously with an internal combustion engine, and a thyristor Th conducted upon receiving an ignition signal Vi for discharging electric charge of the condenser C1 through a primary coil 3a of the ignition coil 3. An overlapping discharging capacitor C2 is connected to both ends of an overlapping discharge generating coil W2 arranged in a magnetic generator through a diode D3. Voltage on both ends of the overlapping discharging capacitor C2 is overlapped with high voltage Vh induced on a secondary coil 3b of the ignition coil with the same polarity and applied to an ignition plug 7 for performing overlapping discharging, and thereby elongating discharge duration time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, air pollution by exhaust gas of an internal combustion engine has become a social problem, and there is a strong demand for purifying the exhaust gas of the internal combustion engine. In particular, in a two-stroke engine, since the exhaust gas is contaminated by blow-by (a phenomenon in which part of fresh air blows into an exhaust port during scavenging), the necessity of purifying the exhaust gas is emphasized. Various researches are being conducted in order to take countermeasures.

As one method for preventing blow-by in a two-cycle engine, an injector (fuel injection valve) is mounted on a cylinder of the engine.
And in-cylinder injection for injecting fuel directly into the cylinder is about to be performed. When performing this in-cylinder injection, fuel injection is performed after the exhaust port is closed,
Alternatively, the fuel injection timing is set so that the injected fuel does not reach the exhaust port or the scavenging port, and the fuel is ignited by generating a spark at the ignition plug at a predetermined ignition position. To burn.

In order to purify the exhaust gas, it is necessary to completely burn the fuel, and for that purpose, it is necessary that the fuel is sufficiently vaporized at the time of ignition. is there.

In order to perform in-cylinder injection, it is necessary to vaporize the fuel in a short period of time from when the fuel is injected to when the ignition is performed. Therefore, a device for promoting vaporization is required.
Generally, in order to promote the vaporization of the injected fuel, it is necessary to reduce the particle size of the injected fuel as much as possible, for which, for example, by increasing the pressure of the fuel supplied to the injector from a fuel pump. It is said that it is effective.

[0006] However, no matter what measures are taken to promote the vaporization of the fuel, in practice, it often does not go as desired, and especially when the engine is running at high speed, the ignition is performed after the fuel is injected. Since the time until the operation is performed is extremely short, it is often difficult to sufficiently vaporize the injected fuel.

If ignition is performed in a state where the fuel is not sufficiently vaporized, soot is generated because the fuel is not completely burned, and carbon adheres to the electrode portion of the ignition plug. If carbon adheres to the electrode part of the spark plug, the dielectric strength between the electrodes will decrease, and when a voltage for ignition is applied to the spark plug, a leak current will flow and the voltage applied between the electrodes will decrease. , Sparks may fail. In order to restore the carbon-attached ignition plug to a normal state, it is necessary to burn a large amount of current from the ignition device to the ignition plug to burn off the carbon attached to the electrode portion of the ignition plug.

Further, in order to purify exhaust gas by performing in-cylinder injection, it is necessary to perform combustion by reducing the concentration of the air-fuel mixture (as a lean air-fuel mixture). In order to completely burn the lean air-fuel mixture, it is necessary to make the duration of the spark discharge generated during the ignition operation sufficiently long. If the duration of the spark discharge is extended, energy can be injected into the center of the flame nucleus generated by the combustion of the air-fuel mixture to prevent the flame nucleus from cooling. Becomes possible.

Therefore, the internal combustion engine igniter for performing in-cylinder injection can supply a sufficiently large current to the ignition plug and sufficiently increase the discharge duration to satisfy the above two requirements. It is desirable to be able to do it.

In an ignition device for an internal combustion engine, an electric charge stored in an ignition energy storage capacitor provided on a primary side of the ignition coil is discharged through the primary coil of the ignition coil at an ignition position, so that the ignition coil is recharged. A capacitor discharge type ignition device for generating a high voltage for ignition in a secondary coil, and a current flowing through a primary coil of an ignition coil or an ignition power supply coil connected in parallel to the primary coil is cut off at an ignition position. There is known a current interruption type ignition device that generates a high voltage for ignition in a secondary coil of the ignition coil.

Among them, the capacitor discharge type ignition device can obtain a large amount of current that can flow from the secondary coil of the ignition coil to the ignition plug, but has a problem that the discharge duration is short. . On the other hand, the current interruption type ignition device has a problem in that the discharge duration can be lengthened, but the current flowing from the secondary coil of the ignition coil to the ignition plug cannot be increased.

Therefore, the output voltage of the battery is set to 1000
Using a DC-DC converter that boosts the voltage from [V] to 1500 [V] as a power source for a capacitor discharge type ignition device, an ignition energy storage capacitor is charged by the output voltage of the converter, and the output voltage of the converter is reduced. There has been proposed a lap discharge type capacitor discharge type internal combustion engine ignition device in which the duration of discharge is extended by superimposing it on the secondary output voltage of an ignition coil.

According to this ignition device, after a spark is generated in the ignition plug by using the secondary induced voltage of the ignition coil as a trigger, energy is supplied to the discharge gap of the ignition plug by the output voltage of the DC-DC converter to discharge. Since the current can continue to flow, the duration of the spark discharge can be lengthened, and the lean air-fuel mixture can be favorably burned. When carbon adheres to the electrode of the spark plug and a leak current flows between the electrodes, DC-D
Since a large leak current can flow from the C converter between the electrodes of the spark plug to burn off the carbon attached to the electrodes, the spark plug can be restored to a normal state.

[0014]

In a conventional internal combustion engine igniter in which an output voltage of a DC-DC converter is superimposed on an induced voltage of a secondary coil of a capacitor discharge type igniter to perform an overlap discharge, If the output impedance of the DC-DC converter is set to be small, the discharge current flowing from the DC-DC converter to the spark plug does not attenuate forever, so that the ignition spark cannot be extinguished. In order to extinguish the spark at an appropriate time, DC
-It is necessary to suppress the discharge current by increasing the output impedance of the DC converter to increase the voltage drop caused by the output impedance of the converter when the discharge current flows from the converter to the spark plug. However, when the output impedance of the DC-DC converter is increased, it takes time to charge the ignition energy storage capacitor provided on the primary side of the ignition coil by the converter. A problem arises in that the charging voltage of the ignition energy storage capacitor is insufficient and the ignition performance is reduced.

In the above-described ignition device, a battery is used as a power source. However, if a battery is used as a power source for the ignition device, the engine cannot be operated when the battery is over-discharged. Occurs. In particular, in the case of an internal combustion engine used for an outboard motor, a snowmobile, or the like, if the engine cannot be operated, an occupant may be distressed. Therefore, it is not preferable to use a battery-powered ignition device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a capacitor discharge type internal combustion engine ignition system capable of increasing the duration of discharge by causing lap discharge during ignition operation without deteriorating ignition performance at high speed. It is to provide a device.

Another object of the present invention is to provide a large current flowing between the electrodes of the ignition plug to burn off the carbon when the carbon adheres to the electrodes of the ignition plug and a leak current flows. It is an object of the present invention to provide an ignition device for an internal combustion engine that can restore a plug to a normal state.

[0018]

According to the present invention, there is provided a magnet generator provided to rotate synchronously with an internal combustion engine, an ignition coil, and a primary side of the ignition coil provided in the magnet generator. An ignition energy storage capacitor that is charged to one polarity by the output voltage of the exciter coil, and that conducts when an ignition signal is applied to discharge the charge stored in the ignition energy storage capacitor through the primary coil of the ignition coil And an ignition position control means for supplying an ignition signal to the discharge switch at the ignition position of the internal combustion engine. The present invention relates to a capacitor discharge type internal combustion engine ignition device for inducing a high voltage for ignition in a secondary coil.

According to the present invention, a lap discharge power generating coil for generating an output voltage of one half cycle at a rotational angle position advanced in phase from the ignition position of the internal combustion engine is provided separately from the exciter coil in the magnet generator. . Further, a lap discharge capacitor charged with the output voltage of one half cycle of the lap discharge generating coil is provided, and a voltage obtained by superposing the voltage at both ends of the lap discharge capacitor and the high voltage for ignition with the same polarity is applied to the ignition device. And the secondary coil of the ignition coil is connected so as to output as an output voltage.

In the above igniter, when the overlapping discharge generating coil generates a half-cycle voltage of one polarity at the rotation angle position advanced from the ignition position, the overlapping discharging capacitor is turned on by the output voltage of the generating coil. Is charged to the polarity. When an ignition signal is generated at the ignition position, the discharge switch conducts, so that the charge of the ignition energy storage capacitor is discharged through the discharge switch and the primary coil of the ignition coil, and the high voltage for ignition is applied to the secondary coil of the ignition coil. Is induced. A voltage obtained by superimposing the high voltage for ignition and the voltage at both ends of the capacitor for lap discharge is applied to the ignition plug. In the discharge gap of the spark plug, a spark discharge is generated with the ignition high voltage as a trigger voltage, and the engine is ignited. Once discharge occurs in the discharge gap of the spark plug, the impedance of the discharge gap decreases, so a large current flows from the lap discharge capacitor to the spark plug, and energy is supplied to the discharge gap. Therefore, in the discharge gap of the ignition plug, the discharge is maintained even after the high voltage for ignition has disappeared, and the discharge stops when the electric charge accumulated in the capacitor for lap discharge becomes less than a predetermined amount.

As described above, according to the present invention, the lap discharge capacitor charged by the output of the lap discharge coil is provided, and the voltage obtained by superposing the voltage at both ends of the capacitor and the ignition high voltage is applied to the ignition plug. Is applied to
The duration of the spark discharge generated at the time of the ignition operation can be lengthened, and the lean mixture can be favorably burned. The duration of the lap discharge can be adjusted by the capacitance of the lap discharge capacitor and the impedance of the secondary coil of the ignition coil.

Further, when carbon adheres to the electrode of the spark plug and a leak current flows, the electric charge accumulated in the lap discharge capacitor is discharged through the leak resistance of the spark plug, and a large amount of electric charge is applied to the spark plug. Since a leak current can flow, carbon attached to the electrode of the spark plug can be burned off, and the spark plug can be restored to a normal state.

As described above, according to the present invention, when carbon adheres to the spark plug, not only can the carbon be burned off to restore the spark plug to a normal state, but the duration of spark discharge can be extended. As a result, the lean air-fuel mixture can be satisfactorily burned, so that the probability of occurrence of an ignition error can be reduced, the harmful substances in the exhaust gas can be reduced, and the exhaust gas can be purified.

As described above, without providing the capacitor for the lap discharge, the power generation coil for the lap discharge is provided at the ignition position.
The phase of the output of the power generation coil for lap discharge is set so that the voltage of the power generation coil for lap discharge is generated so as to generate a sufficiently large voltage for lap discharge having the same polarity as the high voltage for ignition. Even when superimposed on a high voltage, it is possible to cause an overlap discharge. However, in the case of such a configuration, the phase of the output of the lap discharge power generation coil and the phase of the high voltage for ignition cannot be properly matched due to the number of poles of the magnet generator and the like. In some cases, discharge cannot be performed. In particular, when it is necessary to increase the advance width of the ignition position, it may be difficult to match the phase of the output voltage of the lapping discharge power generation coil and the phase of the ignition high voltage during the advance.

On the other hand, according to the present invention, the capacitor for the lap discharge is charged with the output of the coil for the lap discharge, and the voltage across the capacitor is superimposed on the high voltage for ignition.
Irrespective of the number of poles of the magnet generator, the overlapping discharge can be performed by superimposing the overlapping discharge voltage on the ignition high voltage.

When the output of the superposition discharge power generation coil is directly superimposed on the high voltage for ignition, the impedance of the secondary coil of the ignition coil is reduced in order to increase the current flowing through the ignition plug. It is necessary to set the secondary impedance of the ignition coil.
When the lap discharge capacitor is provided as described above and the charge of the capacitor is discharged through the secondary coil, the capacitor exhibits a low impedance with respect to a high-frequency discharge current. Even if the impedance is increased, a sufficiently large current can flow through the spark plug. Therefore, with the configuration described above, the impedance on the secondary side of the ignition coil can be set freely, and the degree of freedom in design can be increased.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a configuration for one cylinder of an internal combustion engine ignition device according to the present invention. In FIG. 1, 1 is a magnet generator provided so as to rotate synchronously with the internal combustion engine, 3 is an ignition coil having a primary coil 3a and a secondary coil 3b, 4 is an ignition circuit for controlling a primary current of the ignition coil 3, Reference numeral 5 denotes an ignition control unit, and reference numeral 7 denotes an ignition plug attached to a cylinder of the internal combustion engine.

The magnet generator 1 has an exciter coil W1 and a lap discharge power generating coil W2 on the stator side, and induces an AC voltage in both coils in synchronization with the rotation of the engine. The exciter coil W1 is wound with a sufficiently large number of turns using a relatively thin coil conductor so as to induce a voltage of 200 to 300 [V] even at a low speed of the engine. In addition, the power generation coil W2 for lap discharge
Is an AC voltage (e.g., 1000 to 1500) having a peak value required to sustain a spark discharge generated in a discharge gap of the ignition plug 7 using a high voltage for ignition induced in a secondary coil of the ignition coil as a trigger voltage during an ignition operation. [V]), the number of turns is set.

In the example shown in the figure, the rotor of the magnet generator is constituted by two poles so that one cycle of AC voltage is induced in the exciter coil W1 and the lap discharge generating coil W2 during one rotation of the engine. It has become.

The ignition circuit 4 includes an ignition energy storage capacitor C1 and a thyristor Th constituting a discharge switch.
And diodes D1 and D2.
The ignition energy storage capacitor C1 is connected between one end of the primary coil 3a of the ignition coil 3 and ground, and the thyristor Th is connected between the other end of the primary coil 3a and ground with the cathode facing the ground. ing. One end of the exciter coil W1 is grounded, and the non-ground side terminal of the exciter coil is connected to a connection point between the capacitor C1 and the primary coil 3a through a diode D1 whose anode is directed toward the exciter coil. Primary coil of ignition coil 3
A diode D2 whose anode is directed to the anode side of the thyristor Th is connected to both ends of a.

One end of the overlapping discharge power generating coil W2 is grounded, and the other end of the generating coil W2 is connected to one end of the overlapping discharging capacitor C2 through a diode D3 whose anode is directed toward the power generating coil W2. The other end of the capacitor C2 is grounded, and the non-grounded terminal of the capacitor C2 is connected to one end of the secondary coil 3b of the ignition coil 3.
The other end of the secondary coil 3b of the ignition coil 3 is connected to a non-ground terminal of the ignition plug 7 through a high-voltage cord.

The lap discharge generating coil W2 generates an AC voltage in synchronism with the rotation of the internal combustion engine. The output voltage of one half cycle of the AC voltage is applied to the lap discharge capacitor C2 through the diode D3 so that the lap discharge capacitor C2 has one polarity. Is charged. The voltage Vc across the capacitor C2 is superposed with the same polarity as the ignition high voltage Vh generated across the secondary coil 3b of the ignition coil and is output as the output voltage of the ignition device (applied to the ignition plug 7). So that the capacitor C2
Is set, and the polarity of the ignition high voltage Vh induced in the secondary coil 3b is set.

The ignition control unit 5 has a microcomputer. The microcomputer executes a predetermined program so that the ignition signal Vi is applied to the gate of the thyristor Th constituting a discharge switch at the ignition position of the internal combustion engine. The ignition position control means to be provided is realized.

The ignition control unit 5 does not necessarily need to be configured using a microcomputer, but may be configured to generate an ignition signal using a hardware circuit.

In the internal combustion engine ignition device shown in FIG.
The exciter coil W1 outputs one cycle of the AC voltage V1 during one revolution of the engine. The output voltage of one half cycle of the exciter coil W1 charges the capacitor C1 through the diode D1 to the polarity shown. As shown in FIG. 2A, when the ignition control unit 5 generates an ignition signal Vi at the ignition position θi of the internal combustion engine,
Since the thyristor Th conducts, the electric charge of the capacitor C1 is discharged through the thyristor Th and the primary coil 3a of the ignition coil. This discharge induces a high ignition voltage Vh in the secondary coil 3b of the ignition coil 3. The overlapping discharge power generating coil W2 generates an AC voltage V2 as shown by a chain line in FIG. 2 (B). In one half cycle (positive half cycle in the illustrated example) of this AC voltage, the power is passed through a diode D3. The capacitor C2 is charged. The voltage Vc across the lap discharge capacitor C2 is shown in FIG.
As shown in the figure. Overlap discharge capacitor C
2 is superposed on the ignition high voltage Vh with the same polarity and applied to the ignition plug 7.

A spark discharge is generated in the discharge gap of the ignition plug 7 with the ignition high voltage Vh as a trigger voltage.
The discharge current i2 flows as shown in FIG. Once discharge occurs in the discharge gap of the spark plug, the impedance of the discharge gap decreases, so that the lap discharge capacitor C2
A large current flows through the discharge gap of the spark plug 7, and the terminal voltage Vc of the capacitor C2 decreases as shown in FIG. Energy is supplied to the discharge gap of the ignition plug by the discharge of the electric charge stored in the lap discharge capacitor C2. Therefore, the discharge current continues to flow in the discharge gap of the ignition plug even after the high voltage for ignition Vh has disappeared, and the spark discharge continues. The spark discharge is the capacitor C2
Is discharged, and disappears when the energy supplied to the discharge gap of the ignition plug becomes less than the magnitude required to maintain the discharge. The duration of the overlap discharge is determined by the capacitance of the overlap discharge capacitor and the secondary coil 3b of the ignition coil.
And the impedance can be adjusted as appropriate.

As described above, according to the present invention, a spark discharge having a long duration can be generated in the spark plug at the ignition position, so that even if the mixture in the cylinder of the engine is a lean mixture, Combustion can be favorably performed.

When carbon adheres to the electrodes of the ignition plug 2 and a leak occurs between the electrodes, the electric charge accumulated in the lap discharge capacitor C2 causes a large leakage through the electrodes of the ignition plug 2. Since current can be applied to burn off the carbon attached to the electrode, the electrode of the spark plug can be restored to a normal state.

Further, as described above, the capacitor C2 for lap discharge is charged with the output voltage of the power generation coil for lap discharge,
When the capacitor C2 is discharged through the secondary coil of the ignition coil to perform lap discharge,
As indicated by broken lines in FIGS. 2A and 2B, the ignition signal V
Even when the generation position (ignition position) of i is advanced from θi to θi ', the electric charge of the capacitor C2 can be discharged through the secondary coil of the ignition coil to perform the overlapping discharge. The angular width can be widened.

In the above example, the ignition energy storage capacitor C1 is connected between one end of the primary coil 3a of the ignition coil and the ground, but the configuration of the circuit on the primary side of the ignition coil is not limited to the above example. For example, in FIG. 1, the capacitor C1 is connected between one end of the primary coil 3a and the cathode of the diode D1, and the other end of the primary coil 3a is grounded, and between the connection point of the capacitor C1 and the diode D1 and ground. A well-known circuit for connecting the thyristor Th can also be used. In this case, the diode D
2 is the primary coil 3 with its cathode facing the ground side.
a in parallel.

In the above example, the magnet generator has two poles. However, the present invention can of course be applied to a case where a multi-pole magnet generator is used.

In the example shown in FIG. 1, the exciter coil W
Although only one is provided, both a low-speed exciter coil that generates a high voltage at a high speed of the engine and a high-speed exciter coil that generates a high voltage at a high speed of the engine are provided. The present invention can be applied to a case where a circuit for charging the ignition energy storage capacitor C1 with the outputs of both exciter coils is employed.

[0043]

As described above, according to the present invention, when carbon adheres to the spark plug, not only can the carbon be burned off to restore the spark plug to a normal state, but also the duration of the spark discharge can be reduced. , The combustion of a lean mixture can also be performed satisfactorily, so that the probability of occurrence of an ignition mistake can be reduced, the harmful substances in the exhaust gas can be reduced, and the exhaust gas can be purified. There are advantages that can be done.

Further, according to the present invention, the capacitor for the lap discharge is charged with the output voltage of the coil for the lap discharge, and the voltage at both ends of the capacitor is superimposed on the high voltage for ignition with the same polarity. Irrespective of the number of poles, the overlapping discharge voltage can be superimposed on the ignition high voltage to perform the overlapping discharge.

Further, according to the present invention, even if the impedance on the secondary side of the ignition coil is increased by flowing the discharge current through the lap discharge capacitor and the secondary coil having a low impedance with respect to the discharge current, Since a sufficiently large current can be passed through the ignition plug, there is an advantage that the impedance on the secondary side of the ignition coil can be set freely.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration example of an internal combustion engine ignition device according to the present invention.

FIG. 2 is a waveform diagram showing a voltage waveform and a signal waveform of each part in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnet generator 3 Ignition coil 5 Ignition control part W1 Exciter coil W2 Overlap discharge generation coil C1 Ignition energy storage capacitor C2 Overlap discharge capacitor Th thyristor (discharge switch) D1 diode D3 diode

Claims (1)

[Claims] An output voltage of a magnet generator provided to rotate synchronously with an internal combustion engine, an ignition coil, and one of output voltages of an exciter coil provided on the primary side of the ignition coil and provided in the magnet generator. An ignition energy storage capacitor charged to the polarity of the ignition coil, and provided so as to conduct when an ignition signal is given, and discharge the electric charge stored in the ignition energy storage capacitor through the primary coil of the ignition coil. A discharge switch, and ignition position control means for giving an ignition signal to the discharge switch at an ignition position of the internal combustion engine, wherein the secondary coil of the ignition coil is discharged by discharging electric charges stored in the ignition energy storage capacitor. In the capacitor discharge type internal combustion engine ignition device for inducing a high voltage for ignition, the phase is advanced from the ignition position of the internal combustion engine. A lap discharge power generating coil for generating an output voltage of one half cycle at the turning angle position is provided separately from the exciter coil in the magnet generator, and charged by the output voltage of one half cycle of the lap discharge coil. Is provided, and a voltage obtained by superimposing a voltage at both ends of the overlap discharge capacitor and the high voltage for ignition with the same polarity is output as an output voltage of the ignition device. An internal combustion engine ignition device, wherein a capacitor and a secondary coil of an ignition coil are connected.