JPH05133317A - Internal combustion engine ignition method and device of capacitor discharge type - Google Patents

Abstract

PURPOSE:To prevent occurrence of incomplete combustion in the case fuel becomes lean. CONSTITUTION:A switch element such as FET 7 that can be forcibly disconnected is used as a discharging switch for discharging a capacitor 2. When an ignition signal V1 which decides the ignition timing of an internal combustion engine is generated, a trigger signal Vt is given to the FET 7 to turn on this switch. As a result, electric change of the capacitor 2 is discharged to the primary coil of an ignition coil 1 through the FET 7. When the discharge current has reached a set value, the FET 7 is turned off by making the trigger signal Vt zero to once stop the discharge of the capacitor 2. After the lapse of a predetermined time period, the trigger signal Vt is given to the FET 7 again to restart the discharge.

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 internal combustion engine ignition method and an ignition device used for implementing the method.

[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, at the time of sudden acceleration of the engine, the fuel becomes thinner than during steady operation, so combustion after ignition becomes incomplete,
There was a problem that the output of the engine could not be fully 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 a capacitor for storing ignition energy to a primary coil of an ignition coil, the rise of 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, so that the secondary voltage of the ignition coil rises quickly and the secondary discharge current (spark current) continues. There is a need for long time ignition devices.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 60-204968, two sets of capacitor discharge circuits each consisting of a capacitor for storing ignition energy and a discharge switch for discharging the electric charge of the capacitor to the primary coil of the ignition coil are disclosed. A capacitor discharge type ignition device has been proposed which is provided so as to perform double ignition.

In this ignition device, one of the ignition energy storage capacitors is discharged at the regular ignition position to perform the first ignition operation, and then the other ignition is slightly delayed from the regular ignition position. By discharging the energy storage capacitor and performing the second ignition operation, the apparent discharge time is lengthened to prevent incomplete combustion when the fuel is lean.

[0006]

In a conventional capacitor discharge type ignition device for performing double ignition, a capacitor and a switch for discharging the electric charge of the capacitor are provided in two.
Since a group is required, there is a problem that the device configuration becomes complicated.

Further, since it is necessary to charge the two ignition energy storage capacitors, it is necessary to use one having a large capacity as a power source for charging the capacitors, which is in combination with the need for two capacitors and switches. There is a problem that the device becomes large in size.

An object of the present invention is to ignite a capacitor discharge type internal combustion engine capable of obtaining a characteristic that the secondary voltage rises quickly and the secondary discharge current has a long duration without increasing the size of the device. It is to provide a method and an apparatus used to carry out the method.

[0009]

An ignition method according to the present invention charges an ignition energy storage capacitor to one polarity,
A capacitor discharge type internal combustion engine ignition method for inducing a high voltage for ignition in a secondary coil of an ignition coil by discharging an electric charge of an ignition energy storage capacitor through a primary coil of an ignition coil at an ignition timing of the internal combustion engine Is.

In the present invention, the process of stopping the discharge of the capacitor when the discharge current of the capacitor reaches a set value after starting the discharge of the ignition energy storage capacitor, and after stopping the discharge of the capacitor And a process of restarting the discharge of the ignition energy storage capacitor when a predetermined time has elapsed. The number of times the discharge is repeated is arbitrary.

The ignition device of the present invention for carrying out the above-mentioned ignition method includes an ignition energy storage capacitor provided on the primary side of an ignition coil, and a capacitor charging circuit for charging the ignition energy storage capacitor to one 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 signal for generating an ignition signal for determining the ignition timing of the internal combustion engine A capacitor discharge type internal combustion engine ignition device comprising a generator and a damper diode connected in parallel to a primary coil of an ignition coil, and in the present invention, discharge current detection for detecting a discharge current of an ignition energy storage capacitor. Discharge detected by the discharge current detection circuit by connecting the circuit and the discharge switch when an ignition signal is generated. When the current reaches the set value, the discharge switch is turned off, and the discharge switch is controlled to re-conduct when a certain time has passed since the discharge switch was turned off. And a switch control circuit.

The damper diode is a diode connected in a direction in which the voltage induced in the primary coil of the ignition coil is applied in the forward direction when the discharge current of the capacitor becomes zero. It is the same as that used in the capacitor discharge ignition device.

The discharge switch control circuit is, for example,
A trigger signal supply circuit that supplies a trigger to the discharge switch when an ignition signal is generated, a discharge stop command circuit that outputs a discharge stop command signal when the detection output of the discharge current detection circuit reaches a set value, and a discharge A trigger signal supply control circuit that prevents the trigger signal supply circuit from supplying the trigger signal when the stop command signal is generated, starts the timed operation, and restarts the supply of the trigger signal by the trigger signal when the timed operation is completed. It can be configured with.

[0014]

When the ignition of the ignition energy storage capacitor is discharged to the primary coil of the ignition coil, an induced voltage with a fast rise is generated on the secondary side of the ignition coil. When the discharge of the capacitor is stopped when the discharge current of the capacitor reaches a predetermined value, a voltage of high polarity is induced in the primary coil of the ignition coil, which tends to keep the current that has been flowing until then.

In the capacitor discharge type ignition device, almost the ignition performance (secondary output of the ignition coil) is obtained due to the change of the current in the process of the primary current of the ignition coil rising toward the peak.
When the primary current becomes sufficiently large and the magnetic flux of the iron core is saturated, the secondary output of the ignition coil begins to decrease thereafter.

Therefore, in order to increase the energy efficiency, it is preferable to stop the discharge of the capacitor when the discharge current of the ignition energy storage capacitor reaches a predetermined value. If the first discharge of the ignition energy storage capacitor is stopped halfway in this way, sufficient electric charge still remains in the capacitor, so that the second and subsequent discharges can be sufficiently performed.

Therefore, in the present invention, the discharge is temporarily stopped when the discharge current of the ignition energy storage capacitor reaches a set value, and then the discharge is restarted after a certain period of time. In this way, the induced voltage can be generated multiple times in succession on the secondary side of the ignition coil to prolong the discharge time, and complete combustion can be performed even when the fuel becomes lean. it can.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 denotes an ignition coil having a primary coil 1a and a secondary coil 1b, one end of which is grounded, Two
Is an ignition energy storage capacitor whose one end is connected to the non-grounded side terminal of the primary coil 1a of the ignition coil, and 3 is an ignition plug which is attached to a cylinder of an engine (not shown) and is connected to the secondary coil 1b of the ignition coil. is there.

Reference numeral 5 denotes an exciter coil which is provided in a magnet generator attached to the internal combustion engine and has one end grounded.
The non-grounded side terminal of the exciter coil 5 is connected to the other end of the capacitor 2 through the diode 6. 7 is a field effect transistor (FET) that constitutes a discharge switch
The drain is connected to the connection point between the capacitor 2 and the diode 6, and the source is grounded through the resistor R1. The resistance value of the resistor R1 is set sufficiently small, and the discharge current detection circuit 8 is constituted by the resistor R1.

A signal source 9 outputs a signal Vs containing information for determining the ignition timing of the engine. Examples of the signal source include a generator coil provided in a magneto generator attached to the internal combustion engine, and an engine. A signal coil or the like provided in the signal generating device that outputs a signal in synchronization with is used. The output of the signal source 9 is input to the ignition timing control device 10, and the output of the ignition timing control device 10 is the transistor Tr1 and the resistor R2.
, And R3 are input to the discharge switch control circuit 12 through a signal output circuit 11.

The ignition timing control device 10 inputs the output of the signal source 9 to calculate the ignition timing at each engine speed,
At the calculated ignition timing, the potential of the output terminal is set to zero level (ground level), and the base current is passed through the transistor Tr1. As a result, the transistor Tr1 becomes conductive, and the ignition signal Vi is output through the resistor R3.

In this embodiment, the signal generator 9, the ignition timing control device 10, and the signal output circuit 11 are used for the signal generator 13.
Is configured.

The ignition timing control device 10 may be composed of an electronic circuit or a microcomputer. Further, the ignition timing control device 10 may be omitted and the signal generator 13 may be configured only by the signal source 9.

In many cases, the signal source 9 includes a signal generator containing a signal coil and a permanent magnet that generates a magnetic flux interlinking with the signal coil, and an outer peripheral portion or a boss of the rotor yoke of the magnet rotor. And a reluctor (inductor) that is provided in a part or the like and changes the magnetic flux that links the signal coil when facing the signal generator to induce a signal voltage in the signal coil. In some cases, a signal generator that is provided separately from and is used. Also recently
Hall IC is used instead of the signal coil.
There is also one that generates a signal by detecting a change in magnetic flux.

The discharge switch control circuit 12 includes a trigger signal supply circuit 12A composed of transistors Tr2 and Tr3 and a resistor R4, a discharge stop command circuit 12B composed of a comparator CP1 and resistors R5 and R6, a comparator CP2 and a transistor And a trigger signal supply control circuit composed of Tr3, a capacitor C1 and resistors R7 to R12. Here, the trigger signal supply circuit 12A is a circuit for supplying a trigger Vt to the discharge switch 7 when the ignition signal Vi is generated,
The discharge stop command circuit 12B is a circuit that outputs a discharge stop command signal when the detection output Vd of the discharge current detection circuit 8 reaches the set value Vr1. Also, the trigger signal supply control circuit 1
2C is a circuit that blocks the supply of the trigger signal by the trigger signal supply circuit when the discharge stop command signal is generated, starts the timed operation, and restarts the supply of the trigger signal by the trigger signal when the timed operation is completed. is there.

In this embodiment, the damper diode 14 is connected in parallel with the primary coil of the ignition coil 1. This damper diode 14 is provided for the primary coil 1a when the discharge of the ignition energy storage capacitor 2 is stopped.
The connection is made so that the voltage induced in is applied in the forward direction.

In the circuit of FIG. 1, the terminal labeled E is connected to the positive output terminal of a DC power supply (not shown). This DC power supply is composed of a battery,
Alternatively, it comprises an exciter coil 5, a rectifier circuit for rectifying the output of the exciter coil, and a constant voltage circuit for controlling the output voltage of the rectifier circuit so as to keep the output voltage substantially constant.

Next, the operation of the above embodiment will be described. The ignition energy storage capacitor 2 is charged with the output voltage of the exciter coil in a half cycle to the polarity shown in the figure through the diode 6, and the terminal voltage Vc of the capacitor 2 rises as shown in FIG. 2 (F). .. Note that V in FIG. 2 (E)
c indicates the potential at the connection point between the capacitor 2 and the field effect transistor 7.

The signal source 9 outputs signals Vs1 and Vs2 containing 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, and the ignition timing control device 10 inputs these signals. As a result, the transistor Tr1 is turned on at the ignition timing of the engine, and the ignition signal V is supplied through the transistor Tr1 and the resistor R3 as shown in FIG.
Output i.

Since the voltage across the resistor R1 is zero before the capacitor 2 starts discharging, the comparator CP1
Is at a high level, and the transistor Tr3 is in the cutoff state at this time. Therefore, the voltage across the capacitor C1 is zero and the output of the comparator CP2 is high.

When the ignition signal Vi is generated, the transistor Tr2 becomes conductive at the rising edge of the ignition signal Vi, and the field effect transistor 7 is connected from the DC power source through the transistor Tr2 and the resistor R4.
A trigger signal Vt is applied to the gate of the. As a result, the field effect transistor 7 becomes conductive, and the electric charge of the capacitor 2 is discharged through the field effect transistor 7, the resistor R1 and the primary coil 1a of the ignition coil. When the capacitor 2 discharges, 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 R6, so that the output of the comparator CP1 is zero level (ground potential).
Fall to. 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 Tr3 becomes conductive, so that the capacitor C1 is charged from the DC power supply (not shown) through the transistor Tr3 and the resistor R9. Since the resistance value of the resistor R9 is set to be sufficiently small, the capacitor C1 is charged almost instantly, and the voltage across the capacitor C1 rises almost instantly as shown in FIG. 2 (E). At this time, since the voltage across the capacitor C1 exceeds the set voltage Vr2 obtained across the resistor R12, the output of the comparator CP2 becomes zero level (ground level) and the transistor Tr3 becomes conductive. Therefore, the transistor Tr2 is cut off, and the trigger signal Vt of the field effect transistor 7 becomes zero. As a result, the field effect transistor 7 is cut off and the discharge of the capacitor C2 is stopped.

As shown in FIG. 2 (E), the capacitor C1
Is discharged through the resistor R10 with a constant time constant. When the terminal voltage of the capacitor C1 becomes lower than the set value Vr2, the output voltage of the comparator CP2 becomes high level, the transistor Tr3 is cut off, and the trigger signal Vt is given to the field effect transistor 7 again. As a result, the field effect transistor 7 becomes conductive, and the residual charge of the capacitor 2 is discharged to the primary coil of the ignition coil 1.

Since the same operation is repeated as long as the residual charge of the capacitor 2 is present, the residual charge of the capacitor 2 is gradually discharged through the primary coil of the ignition coil, and the secondary coil of the ignition coil 1 becomes high. The voltage is repeatedly generated. Therefore, sparks are repeatedly generated in the spark plug 3, and the discharge duration time is extended.

In the above embodiment, the set value of the discharge current of the capacitor 2 (determined by the reference voltage Vr1) is set to a value near the minimum value of the current value in the range where the iron core of the ignition coil is magnetically saturated, for example. I'll do it. With this setting, even if the discharge of the capacitor 2 is stopped midway, the secondary output of the ignition coil does not decrease, and the peak value of the high voltage induced in the secondary coil of the ignition coil at the ignition timing. Is equivalent to the conventional one.

As described above, according to the present invention, a high voltage for ignition having a peak value equivalent to that obtained by the conventional ignition device can be obtained and the discharge duration can be lengthened. Ignition performance can be improved significantly. Therefore, even if the fuel becomes lean at the time of sudden acceleration of the engine, it is possible to reliably ignite the fuel,
Incomplete combustion can be prevented from occurring.

Repeated discharge of the ignition energy storage capacitor is possible as long as electric charge remains in the capacitor, and the time width of the ignition signal Vi output from the ignition signal generator 13 or the discharge time constant of the capacitor C1 is adjusted. By doing so, the number of times the capacitor is repeatedly discharged (the duration of the secondary discharge current) can be adjusted.

In the above embodiment, the discharging switch is constituted by the field effect transistor 7. However, the discharging switch may be any one that can be forcibly turned off by giving a predetermined signal to the control terminal. Other switch elements such as transistors may be used.

In the above embodiment, the ignition energy storage capacitor 2 is charged by the output of the exciter coil 5, but when the ignition energy storage capacitor is charged by using the DC-DC converter which boosts the voltage of the battery. The present invention can also be applied to.

In the above embodiment, multiple ignition is performed in the entire rotation range, but multiple ignition may be performed only in a predetermined rotation range. For example, when igniting an engine in which the secondary discharge current needs to be lengthened only during idling, multiple ignition can be performed only in a region where the rotational speed is low.

[0040]

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 then restarted after a certain period of time. Therefore, it is possible to continuously generate the induced voltage having a fast rise on the secondary side of the ignition coil a plurality of times to prolong the discharge time and improve the ignition performance.

Further, according to the present invention, since it is sufficient to provide only one ignition energy storage capacitor and one discharge switch, the ignition circuit does not become complicated.
Since it is sufficient to charge each ignition energy storage capacitor, it is possible to use a small capacity power source for charging.

Therefore, according to the present invention, it is possible to improve the ignition performance without making the ignition device large in size and to completely perform the combustion when the fuel becomes lean.

[Brief description of drawings]

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

2A to 2F are waveform diagrams showing voltage waveforms at various portions of the embodiment of FIG.

[Explanation of symbols]

1 ... Ignition coil, 2 ... Ignition energy storage capacitor, 3 ... Ignition plug, 5 ... Exciter coil, 6 ... Diode, 9 ... Signal source, 10 ... Ignition timing control device, 12 ...
Discharge switch control circuit, 12A ... Trigger signal supply circuit, 12B ... Discharge stop command circuit, 12C ... Trigger signal supply control circuit, 13 ... Ignition signal generator, 14 ... Damper diode.

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[Procedure amendment]

[Submission date] April 15, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014]

When the electric charge of the ignition energy storage capacitor is discharged to the primary coil of the ignition coil, an induced voltage with a fast rise is generated on the secondary side of the ignition coil. When the discharge of the capacitor is stopped when the discharge current of the capacitor reaches a predetermined value, a voltage of high polarity is induced in the primary coil of the ignition coil, which tends to keep the current that has been flowing until then.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

The discharge switch control circuit 12 includes a trigger signal supply circuit 12A composed of transistors Tr2 and Tr3 and a resistor R4, a discharge stop command circuit 12B composed of a comparator CP1 and resistors R5 and R6, a comparator CP2 and a transistor A trigger signal supply control circuit 12C composed of Tr3, a capacitor C1 and resistors R7 to R12. Here, the trigger signal supply circuit 12A is a circuit that supplies the trigger signal Vt to the discharge switch 7 when the ignition signal Vi is generated, and the discharge stop command circuit 12B is such that the detection output Vd of the discharge current detection circuit 8 is the set value. It is a circuit that outputs a discharge stop command signal when the voltage reaches Vr1. The trigger signal supply control circuit 12C prevents the trigger signal supply circuit from supplying the trigger signal when the discharge stop command signal is generated and starts the timed operation, and when the timed operation is completed, the trigger signal supply control circuit 12C outputs the trigger signal of the trigger signal. It is a circuit that restarts the supply.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

Next, the operation of the above embodiment will be described. The ignition energy storage capacitor 2 is charged with the output voltage of the exciter coil in a half cycle to the polarity shown in the figure through the diode 6, and the terminal voltage Vc of the capacitor 2 rises as shown in FIG. 2 (F). .. Note that V in FIG. 2 ( F )
c indicates the potential at the connection point between the capacitor 2 and the field effect transistor 7.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

When the ignition signal Vi is generated, the transistor Tr2 becomes conductive at the rising edge of the ignition signal Vi, and the field effect transistor 7 is connected from the DC power source through the transistor Tr2 and the resistor R4.
A trigger signal Vt is applied to the gate of the. As a result, the field effect transistor 7 becomes conductive, and the electric charge of the capacitor 2 is discharged through the field effect transistor 7, the resistor R1 and the primary coil 1a of the ignition coil. When the capacitor 2 discharges, 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 R6, so that the output of the comparator CP1 is zero level (ground potential).
Fall to. 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 Tr3 becomes conductive, so that the capacitor C1 is charged from the DC power supply (not shown) through the transistor Tr3 and the resistor R9. Since the resistance value of the resistor R9 is set to be sufficiently small, the capacitor C1 is charged almost instantly, and the voltage across the capacitor C1 rises almost instantly as shown in FIG. 2 (E). At this time, since the voltage across the capacitor C1 exceeds the set voltage Vr2 obtained across the resistor R12, the output of the comparator CP2 becomes zero level (ground level) and the transistor Tr3 becomes conductive. Therefore, the transistor Tr2 is cut off, and the trigger signal Vt of the field effect transistor 7 becomes zero. As a result, the field effect transistor 7 is cut off and the discharge of the capacitor 2 is stopped.

Claims (3)

[Claims] 1. An ignition energy storage capacitor is charged to one polarity, and at the ignition timing of an internal combustion engine, the charge of the ignition energy storage capacitor is discharged through a primary coil of an ignition coil to a secondary coil of the ignition coil. In a capacitor discharge type internal combustion engine ignition method for inducing a high voltage for ignition, after starting the discharge of the ignition energy storage capacitor, the discharge of the capacitor is stopped when the discharge current of the capacitor reaches a set value. A method for igniting a capacitor discharge internal combustion engine, comprising: performing a step and a step of restarting the discharge of the ignition energy storage capacitor after a lapse of a certain time after the discharge of the capacitor is stopped. 2. An ignition energy storage capacitor provided on the primary side of an ignition coil, a capacitor charging circuit for charging the ignition energy storage capacitor to one polarity, and the ignition energy storage capacitor when electrically connected. A discharge switch provided so as to discharge the electric charge of 1 to the primary coil of the ignition coil, and an ignition signal generator for generating an ignition signal for determining the ignition timing of the internal combustion engine,
In a capacitor discharge type internal combustion engine ignition device comprising a damper diode connected in parallel to a primary coil of the ignition coil, a discharge current detection circuit for detecting a discharge current of the ignition energy storage capacitor, and the ignition signal When the discharge switch is turned on, the discharge switch is turned on, and when the discharge current detected by the discharge current detection circuit reaches a set value, the discharge switch is turned off, and the discharge switch is turned off and then kept constant. And a discharge switch control circuit for controlling the discharge switch so that the discharge switch is re-conducted when the time elapses. 3. A trigger signal supply circuit for supplying a trigger to the discharge switch when the ignition signal is generated, and a detection output of the discharge current detection circuit reaches a set value. When a discharge stop command signal that outputs a discharge stop command signal and when the discharge stop command signal is generated, the supply of the trigger signal by the trigger signal supply circuit is blocked and the timed operation is started, and the timed operation is completed. 3. A trigger signal supply control circuit for restarting supply of the trigger signal according to the trigger signal at times.
The capacitor discharge type internal combustion engine ignition device according to item 1.