JPH09310669A - Ignition device for capacitor discharge type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition device for a capacitor discharge type internal combustion engine which can make the number of times of multiplex ignition more than the usual number of times. SOLUTION: An ignition energy accumulating capacitor 2 is charged by the output of a magnet generator 4, and the electric charge of the capacitor 2 is discharged to the primary coil 1a of an ignition coil through a discharging switch 8 for carrying out an ignition motion. When an ignition signal V1 is generated, the discharging switch 8 is controlled through a control circuit 13 so as to repeat turning ON and OFF. In the case of charging the capacitor 2 by the output of the magnetic generator 4, a backup capacitor 15 is simultaneously charged, and when the discharging switch 8 varies from an ON state to an OFF state, the ignition energy accumulating capacitor 2 is charged through an auxiliary charging circuit 17 by voltage at both the ends of the backup capacitor 15 to supplement the electric charge of the capacitor 2.

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 Generally, in an internal combustion engine, the fuel concentration at each rotational speed is adjusted by assuming a steady operating state of the engine. However, when the engine is suddenly accelerated, the fuel becomes thinner than that in the steady operation, so that the ignition is incomplete and the output of the engine cannot be sufficiently obtained. In particular, when an ignition device that ignites an internal combustion engine is a capacitor discharge type ignition device that obtains a high voltage for ignition by discharging the electric charge of an ignition energy storage capacitor to a primary coil of an ignition coil, Although it is possible to obtain a fast secondary voltage, the duration of the discharge current cannot be lengthened, so incomplete combustion often occurs when the fuel becomes lean during rapid acceleration of the engine.

In recent years, as exhaust gas regulations have become stricter, the number of engines adopting a lean burn system has increased. Therefore, the secondary voltage of the ignition coil rises quickly and the secondary discharge current (spark current) continues. There is an increasing need for long time ignition devices.

Therefore, as disclosed in Japanese Patent Laid-Open No. 5-133317, multiple charges are carried out by repeatedly discharging the charge of the ignition energy storage capacitor in the primary coil of the ignition coil at regular time intervals several times. An ignition device of a capacitor discharge type that is designed to be made possible has been proposed.

In this ignition device, an ignition signal is generated by using a switch element, such as a field effect transistor (FET), which can be forcibly turned off as a discharge switch for discharging the ignition energy storage capacitor. When a drive signal is applied to the FET, the FET becomes conductive
Through which the electric charge of the capacitor is discharged to the primary coil of the ignition coil. When the discharge current reaches the set value, the drive signal is set to zero to put the FET in a cutoff state to temporarily stop the discharge of the capacitor, and after a certain period of time, the drive signal is given to the FET again to restart the discharge. 2 for spark plug
Sparks are generated more than once to prolong the duration of the secondary discharge current.

[0006]

In the conventional capacitor discharge type ignition device described above, in which the electric charge of one ignition energy storage capacitor is discharged twice or more to perform multiple ignition. Subsequent discharges use the remaining stored energy consumed in the previous discharge, so
The discharge after the first time is rapidly attenuated. Therefore, 2
There is a problem that the duration of the secondary discharge current cannot be made sufficiently long.

An object of the present invention is to generate multiple sparks by repeating discharge of the ignition energy storage capacitor when the internal combustion engine is ignited, and the stored energy is not rapidly attenuated during the second and subsequent discharges of the capacitor. In this way, it is an object of the present invention to provide a capacitor discharge type internal combustion engine ignition device capable of obtaining the characteristic that the duration of the secondary discharge current is long.

[0008]

SUMMARY OF THE INVENTION According to the present invention, an ignition energy storage capacitor provided on the primary side of an ignition coil and an ignition energy storage capacitor provided by an output of a magneto generator attached to an internal combustion engine are provided. A main charging circuit for charging to polarity, a discharge switch provided to discharge the electric charge of the ignition energy storage capacitor to the primary coil of the ignition coil when conducting, and an ignition for determining the ignition timing of the internal combustion engine An ignition signal generator for generating a signal,
The present invention relates to a capacitor discharge type internal combustion engine ignition device including a discharge switch control circuit that controls a discharge switch so that conduction and interruption of the discharge switch are repeated when an ignition signal is generated.

In the present invention, when the ignition energy storage capacitor is charged by the output of the magnet generator, the backup capacitor charged to one polarity by the output of the magnet generator and the discharging switch are disconnected from the conducting state. And an auxiliary charging circuit for charging the ignition energy storage capacitor with the voltage across the backup capacitor when the state is reached.

In order to control so that conduction and interruption of the discharge switch are repeated when an ignition signal is generated, for example, a discharge current detection circuit for detecting the discharge current of the ignition energy storage capacitor is provided. The discharge switch is turned on when an ignition signal is generated, and the discharge switch is turned off and then turned on again each time the discharge current detected by the discharge current detection circuit reaches a set value. A switch control circuit may be configured.

To charge the ignition energy storage capacitor with the voltage across the backup capacitor, a charging switch and a discharge switch are provided to apply the voltage across the backup capacitor to the ignition energy storage capacitor. Is equipped with a charging switch control circuit that conducts the charging switch before it is re-conducted after being turned off, and the voltage across the backup capacitor when the discharging switch goes from the conducting state to the blocking state. A charging circuit is provided to charge the ignition energy storage capacitor.

With the above arrangement, when the ignition signal is generated at the ignition timing of the internal combustion engine, the discharge switch is turned on and the charge of the ignition energy storage capacitor is discharged to the primary coil of the ignition coil. The secondary voltage of the first rising speed is generated in the next coil. When the magnitude of the discharge current of the ignition energy storage capacitor reaches the set value,
When the discharge switch is turned off and the voltage of the backup capacitor replenishes the stored charge in the ignition energy storage capacitor, and the discharge switch is turned on again, a sufficiently high second secondary voltage is induced in the ignition coil. To be done. In this way, the discharge of the ignition energy storage capacitor and the replenishment of the stored charge of the ignition energy storage capacitor by the voltage of the backup capacitor are repeated, so that the ignition plug is discharged several times in succession at one ignition of the engine. Sparks can be generated to prolong the duration of the secondary discharge current, and even if the fuel becomes lean, the ignition can be completely performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the configuration of an ignition device according to the present invention. In FIG. 1, 1 is a primary coil 1
It is an ignition coil having a and a secondary coil 1b, and one end of the primary coil 1a is grounded. Reference numeral 2 is a capacitor for storing ignition energy, one end of which is connected to a non-grounded side terminal of the primary coil 1a of the ignition coil, and 3 is an ignition plug attached to a cylinder of an engine (not shown) and connected to a secondary coil 1b of the ignition coil. Is.

Reference numeral 5 designates an exciter coil which is provided in a magnet generator 4 attached to the internal combustion engine and has one end grounded. A terminal of the exciter coil 5 which is not grounded is a diode 6
Is connected to the other end of the capacitor 2 through. In the illustrated example, the circuit of the exciter coil 4-diode 6-capacitor 2-ignition coil primary coil 1a-exciter coil 4 constitutes a main charging circuit for charging the ignition energy storage capacitor 2 to one polarity. . A diode 7 with its anode facing the ground side is connected in parallel between both ends of the exciter coil 5.

Reference numeral 8 is a field effect transistor (FET) constituting a discharge switch, the drain of which is the capacitor 2
Is connected to a connection point between the diode 6 and the diode 6, and the source is grounded through a resistor R1 for current detection. The resistance value of the resistor R1 is set to be sufficiently small, and the discharge current detection circuit 9 is constituted by the resistor R1.

Reference numeral 10 is a signal source for outputting a signal Vs containing information for determining the ignition timing of the engine. As the signal source, a generator coil provided in a magneto generator attached to an internal combustion engine or an engine is used. A signal coil or the like provided in the signal generator that outputs a signal in synchronization with is used. The output of the signal source 10 is input to the ignition timing control device 11, and the output of the ignition timing control device 11 is input to the discharge switch control circuit 13 through the signal output circuit 12 including the transistor Tr1 and the resistors R2 and R3. .

The ignition timing control device 11 inputs the output of the signal source 10 to calculate the ignition timing at each engine speed, and sets the potential of its output terminal to zero level (ground level) at the calculated ignition timing. Apply base current to. As a result, the transistor Tr1 becomes conductive,
The ignition signal Vi is output through the resistor R3.

In the example shown in FIG. 1, the signal source 10, the ignition timing controller 11 and the signal output circuit 12 constitute an ignition signal generator 14.

The ignition timing control device 11 may be composed of an electronic circuit or a microcomputer. Further, the ignition timing control device 11 is omitted, and the ignition signal generator 14 is provided only by the signal source 10.
May be configured.

In many cases, the signal source 10 includes a signal generator including a signal coil and a permanent magnet that generates a magnetic flux interlinking with the signal coil, an outer peripheral portion of a rotor yoke of a magnet rotor, and a boss portion. And a reluctor that induces a signal voltage in the signal coil by changing the magnetic flux that links the signal coil when facing the signal generator. In some cases, a signal generator provided separately is used. In recent years, there is also a type in which a Hall IC is used instead of a signal coil, and a signal is generated by detecting a change in magnetic flux by the Hall IC.

The discharge switch control circuit 13 includes a trigger signal supply circuit 13A composed of a diode D1 and a comparator C.
Discharge stop command circuit 13 consisting of P1 and resistors R4 and R5
B, and a trigger signal supply control circuit 13C composed of a comparator CP2, transistors Tr2 and Tr3, a capacitor C1 and resistors R6 to R12. Here, the trigger signal supply circuit 13A is a circuit for supplying the trigger signal Vt to the field effect transistor (discharge switch) 8 when the ignition signal Vi is generated. Further, in the discharge stop command circuit 13B, the detection output Vd of the discharge current detection circuit 9 changes the power supply voltage E to the resistance R.
When the set value Vr1 obtained by dividing the voltage by 4 and R5 is reached, the potential of the output terminal of the comparator CP1 is lowered from the high level state to the ground level to reduce the potential of the output terminal of the comparator. This is a circuit that uses a discharge stop command signal.

The trigger signal supply control circuit 13C is arranged to trigger the trigger signal supply circuit 13A when the discharge stop command signal is generated.
Is a circuit for starting the timed operation and restarting the supply of the trigger signal by the trigger signal supply circuit 13A when the timed operation is completed.

Reference numeral 15 denotes an output voltage of the exciter coil 5 in the direction of the solid arrow shown in the figure, and the ignition energy storage capacitor 2 is provided.
Is a backup capacitor that is charged by the output of the exciter coil to the polarity shown in the figure through the diode 16 when charging.

Reference numeral 17 denotes an auxiliary charging circuit, which is a charging switch 1
8 and a diode D2 and a resistor R13. In the auxiliary charging circuit 17, when the discharging switch 8 is switched from the conducting state to the blocking state, the charging switch 18
Becomes conductive and charges the ignition energy storage capacitor 2 with the voltage across the backup capacitor 15. In the illustrated example, the charging switch 18 is constituted by the PNP transistor Tr4 having the emitter connected to the positive terminal of the backup capacitor 15 and the collector connected to the positive terminal of the ignition energy storage capacitor 2 through the diode D2. ing.

Field-effect transistor (discharging switch)
A charging switch control circuit 19 is provided for controlling the charging switch 18 so that the charging switch 18 becomes conductive after being turned off and before being re-conducted. The charging switch control circuit 19 includes a PNP transistor Tr5, an NPN transistor Tr6, and resistors R14 to R17, and operates based on a signal supplied from the discharging switch control circuit 13.

Further, the ignition energy storage capacitor 2
When the backup capacitor 15 is charged, the backup capacitor 15 also outputs the diode 1 with the output voltage of the exciter coil 5 in a half cycle.
As shown in FIG. 2 (H), the battery is charged to the polarity shown in FIG. 6 and the terminal voltage Vb of the capacitor 15 rises.

The signal source 10 outputs signals Vs1 and Vs2 including information for determining the ignition timing, as shown in FIG. In this example, the signal Vs1 is set to reach the threshold level at the maximum advance position of the engine, and the signal Vs2 is set to reach the threshold level at the minimum advance position. The ignition timing control device 11 calculates the ignition timing of the engine by inputting these signals, and the transistor T is set to the calculated ignition timing.
By making r1 conductive, as shown in FIG. 2B, the ignition signal Vi is output through the emitter-collector of the transistor Tr1 and the resistor R3.

Since the voltage across the resistor R1 is zero before the ignition energy storage capacitor 2 starts to discharge, the output of the comparator CP1 is at a high level, and the transistor Tr2 is in the cutoff state at this time. It is in. Therefore, the voltage across the capacitor C1 is zero, and the comparator CP
The output Vf of 2 is at the high level and the transistor T
r3 is shut off.

When the ignition signal Vi is generated, the diode D
A trigger signal Vt (FIG. 2C) is applied to the gate of the field effect transistor 8 through 1. As a result, the field effect transistor 8 becomes conductive, and the electric charge of the capacitor 2 is transferred to the field effect transistor 8, the resistor R1 and the primary coil 1 of the ignition coil.
discharge through a. When the capacitor 2 is discharged, a detection voltage Vd (about 1 to 4 V) proportional to the discharge current appears across the resistor R1 as shown in FIG. When the discharge current of the capacitor 2 reaches the set value, the detection voltage Vd
Exceeds the reference voltage Vr1 obtained across the resistor R5, the output of the comparator CP1 drops to the zero level (ground potential). The decrease in the output level of the comparator CP1 becomes the discharge stop command signal. When the output of the comparator CP1 becomes the ground level, the transistor Tr2 becomes conductive, so that the capacitor C1 is charged from the DC power supply (not shown) through the transistor Tr2 and the resistor R8. Since the resistance value of the resistor R8 is set to be sufficiently small, the capacitor C1 is charged almost instantly, and the voltage across the capacitor C1 is as shown in FIG.
As shown in (E), it rises almost instantaneously. At this time, the voltage across the capacitor C1 exceeds the set voltage Vr2 obtained across the resistor R11, so the output voltage Vf of the comparator CP2
Becomes low level (ground level) as shown in FIG. 2 (F), and the transistor Tr3 becomes conductive. Transistor Tr3
Is conducted, the ignition signal Vi is short-circuited by the transistor Tr3, so that the trigger signal Vt (FIG. 2C) of the field effect transistor 8 is made zero. As a result, the field effect transistor 8 is turned off and the discharge of the capacitor 2 is stopped.

When the output Vf of the comparator CP2 becomes zero level, the field effect transistor 8 is cut off, and the base current flows through the transistor Tr5 of the charge switch control circuit 19 to make the transistor Tr5 conductive, whereby the transistor Tr6 is turned on. Becomes conductive. Therefore, the charging switch 18 (transistor Tr4) becomes conductive, and the voltage across the backup capacitor 15 starts charging the ignition energy storage capacitor 2 through the transistor Tr4 and the diode D2. Therefore, the terminal voltage Vc of the ignition energy storage capacitor 2 and the voltage Vb across the backup capacitor 15 instantly become the same potential as shown in FIGS. 2 (G) and 2 (H), respectively. After that, the charge of the ignition energy storage capacitor 2 is replenished by the charge of the backup capacitor 15 together with the rise of the charge.

As shown in FIG. 2 (E), the electric charge of the capacitor C1 which has been charged almost instantly and whose terminal voltage Ve exceeds the set value Vr2 is discharged through the resistor R9 with a constant time constant. The terminal voltage Ve of the capacitor C1 is the set value Vr2
When it becomes lower than the above, the output voltage Vf of the comparator CP2 becomes high level, so that the transistor Tr3 is turned off and the transistors Tr5, Tr6 and Tr4 are also turned off. As a result, the charging of the ignition energy storage capacitor 2 by the voltage of the backup capacitor 15 is stopped, the field effect transistor 8 is re-conducted, and the residual charge of the ignition energy storage capacitor 2 supplemented by the backup capacitor 15 is transferred to the ignition coil. The primary coil 1a is discharged.

During the period when the ignition signal Vi is generated,
By the same operation, the ignition energy storage capacitor 2
The discharge of the electric charge to the primary coil 1a of the ignition coil and the replenishment of the residual charge of the ignition energy storage capacitor 2 by the voltage of the backup capacitor 15 are repeated stepwise, and the spark plug 3 is sparked several times. It occurs and the discharge duration is extended.

In the above example, the set value of the discharge current of the ignition energy storage capacitor 2 which is determined by the reference voltage Vr1 is such that the magnitude of the secondary voltage induced by the first discharge of the capacitor 2 is the spark plug 3 Set to a value that will surely generate a spark. With this setting, when the ignition energy storage capacitor 2 is discharged for the second time and thereafter, the ions generated by the previous spark remain in the discharge gap space of the ignition plug 3, It is possible to easily generate the second and subsequent discharges in the spark plug.

As described above, according to the present invention, even if the ignition energy storage capacitor is discharged and its residual charge is reduced, the reduction of the charge of the ignition energy storage capacitor is supplemented by the stored charge of the backup capacitor. Therefore, the number of repetitions of multiple ignition can be increased and the discharge continuation time in the spark plug can be lengthened as compared with the case of the conventional capacitor discharge type ignition device for performing multiple ignition. Therefore, even if the fuel becomes lean during acceleration of the engine, or even if the lean burn system is adopted, it is possible to reliably ignite the fuel and prevent incomplete combustion.

The ignition energy storage capacitor 2
Is possible as long as the charge is replenished by the backup capacitor 15 and the charge of the ignition energy storage capacitor 2 remains, and the time width of the ignition signal Vi output from the ignition signal generator 14 and the discharge of the capacitor C1. By adjusting the time constant, the duration of the secondary discharge current and the number of times the capacitor 2 is repeatedly discharged can be adjusted.

In the above example, the discharge switch is composed of the field effect transistor 8. However, the discharge switch may be any one that can be forcibly turned off by applying a predetermined signal to the control terminal. Other switch elements such as the above may be used.

In the above-mentioned example, the residual charge of the ignition energy storage capacitor is replenished by the voltage of the backup capacitor in all engine rotation regions to cause multiple ignition, but the backup capacitor is used only in a predetermined rotation region. The charge may be replenished, or multiple ignition may be performed only in a predetermined rotation region. For example, when igniting an engine in which the duration of the secondary discharge current needs to be extended only at the time of starting and idling, the residual charge of the ignition energy storage capacitor is replenished with the voltage of the backup capacitor only in the low rotation speed region. Therefore, multiple ignition can be performed.

[0038]

As described above, according to the present invention, the discharge is temporarily stopped when the discharge current of the ignition energy storage capacitor reaches the set value, and the ignition energy storage capacitor is controlled by the voltage across the backup capacitor. Since the discharge is restarted after replenishing the residual charge of, the residual stored energy of the ignition energy storage capacitor is prevented from being rapidly attenuated, and the induced voltage of the rising edge is continued on the secondary side of the ignition coil continuously. It can be generated a plurality of times and the discharge duration can be made sufficiently long to improve the ignition performance. Therefore, according to the present invention, it is possible to completely ignite the fuel even when the fuel becomes lean, and prevent incomplete combustion and discharge of unburned gas.

[Brief description of drawings]

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

2A to 2H are waveform diagrams showing voltage waveforms at various parts of the ignition device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ignition coil 2 Ignition energy storage capacitor 3 Spark plug 4 Magnet generator 5 Exciter coil 6 Diode constituting a main charging circuit 8 Field effect transistor 9 constituting a discharge switch 9 Discharge current detection circuit 10 Signal source 11 Ignition timing control device 13 Discharge Switch Control Circuit 13A Trigger Signal Supply Control Circuit 13B Discharge Stop Command Circuit 13C Trigger Signal Supply Control Circuit 14 Ignition Signal Generator 15 Backup Capacitor 17 Auxiliary Charging Circuit 18 Charging Switch 19 Charging Switch Control Circuit

Claims (2)

[Claims] Claim: What is claimed is: 1. An ignition energy storage capacitor provided on the primary side of an ignition coil, and a main charging circuit for charging the ignition energy storage capacitor to one polarity with an output of a magneto generator attached to an internal combustion engine. A discharge switch provided to discharge the electric charge of the ignition energy storage capacitor to the primary coil of the ignition coil when conducting, and an ignition signal generating an ignition signal for determining the ignition timing of the internal combustion engine Capacitor discharge type internal combustion engine ignition including a signal generator and a discharge switch control circuit for controlling the discharge switch so as to repeatedly conduct and cut off the discharge switch when the ignition signal is generated. In the device, when charging the ignition energy storage capacitor with the output of the magneto generator, the output of the magneto generator is A backup capacitor that is charged to the same polarity, and an auxiliary charging circuit that charges the ignition energy storage capacitor with the voltage across the backup capacitor when the discharge switch changes from the conductive state to the cutoff state. Discharge type internal combustion engine ignition device characterized by: 2. An ignition energy storage capacitor provided on the primary side of the ignition coil, and a main charging circuit for charging the ignition energy storage capacitor to one polarity by an output from a magneto generator attached to an internal combustion engine. A discharge switch provided to discharge the electric charge of the ignition energy storage capacitor to the primary coil of the ignition coil when conducting, and an ignition signal generating an ignition signal for determining the ignition timing of the internal combustion engine A signal generator, a discharge current detection circuit that detects a discharge current of the ignition energy storage capacitor, and a discharge current detected by the discharge current detection circuit when the discharge switch is turned on when the ignition signal is generated. The discharge switch so that the discharge switch is turned off and then re-conducted each time In a capacitor discharge type internal combustion engine ignition device having a discharge switch control circuit for controlling, when charging the ignition energy storage capacitor with the output of the magnet generator, the output of the magnet generator charges one polarity. Backup capacitor, a charging switch provided to apply the voltage across the backup capacitor to the ignition energy storage capacitor when conducting, and re-conducting after the discharging switch is cut off. A charging switch control circuit for conducting the charging switch before being turned on, and the ignition energy storage capacitor with the voltage across the backup capacitor when the discharging switch is switched from the conduction state to the cutoff state. And a capacitor discharge type internal combustion engine, comprising: Engine ignition device.