JP2841943B2 - 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 of igniting a capacitor discharge type internal combustion engine and an igniter used for carrying out the method.

[0002]

2. Description of the Related Art A capacitor discharge type ignition device is known as an ignition device for igniting an internal combustion engine. In this type of ignition device, the ignition energy storage capacitor provided on the primary side of the ignition coil is charged to one polarity, and the charge of the ignition energy storage capacitor is passed through the primary coil of the ignition coil at the ignition timing of the internal combustion engine. By discharging, a high secondary voltage is induced in the ignition coil. As a charging power supply for the ignition energy storage capacitor, an exciter coil provided in the magnet generator or a booster circuit (DC-DC converter) for boosting the voltage of the battery is used.

[0003] In the above-described capacitor discharge type ignition device, a secondary voltage which rises quickly can be obtained.
There is a problem that the duration of the discharge current cannot be extended. However, recently, as the regulations on exhaust gas have become stricter, the number of engines adopting a lean combustion system has increased, so that the secondary voltage of the ignition coil rises quickly and the duration of the secondary discharge current (spark current) is long. An ignition device is needed.

Therefore, as seen in Japanese Patent Publication No. 53-452, a capacitor discharge ignition method in which the secondary voltage rises quickly but the duration of the secondary discharge current is short, and the secondary voltage rises slowly, An ignition device has been proposed which combines a battery cut-off type ignition system with a long secondary discharge current duration.

[0005]

In the conventional ignition device using both the capacitor discharge type and the battery cut-off type, the primary winding number of the ignition coil is required to be 200 to 300 turns, and it is necessary to increase the iron core. The size of the ignition coil was inevitable. In particular, when configuring an ignition device for a multi-cylinder internal combustion engine, a large number of ignition coils are required, so that the size of the ignition device is increased and the weight of the ignition device is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a capacitor discharge type internal combustion engine ignition which can obtain a characteristic in which a secondary voltage rises quickly and a long duration of a secondary discharge current can be obtained without increasing the size of the device. It is to provide a device.

[0007]

According to the present invention, the ignition energy storage capacitor is charged to one polarity, and the charge of the ignition energy storage capacitor is discharged through the primary coil of the ignition coil at the ignition timing of the internal combustion engine. A capacitor discharge type internal combustion engine ignition method for inducing a high voltage for ignition in a secondary coil of an ignition coil. In the present invention, a damper diode is connected in parallel to a primary coil of an ignition coil, and ignition energy is After the discharge of the storage capacitor is started, the process of stopping the discharge of the capacitor when the discharge current of the capacitor reaches the set value, and the ignition when the current flowing through the damper diode falls below a predetermined reference value. The process of restarting the discharge of the energy storage capacitor is repeated.

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. This is the same as that used in the capacitor discharge ignition device.

An ignition device for performing the above-described ignition method includes an ignition energy storage capacitor provided on a primary side of an ignition coil, a capacitor charging circuit for charging the ignition energy storage capacitor to one polarity, and an internal combustion engine. An ignition signal generation device that generates an ignition signal at the ignition timing of, and a discharge switch that conducts when an ignition signal is given and discharges the charge of the ignition energy storage capacitor to the primary coil of the ignition coil; A damper diode connected in parallel to the primary coil of the ignition coil, a discharge stop command circuit for outputting a discharge stop command signal when a discharge current of the ignition energy storage capacitor reaches a predetermined value, and energization of the damper diode A discharge restart command circuit for detecting a current and outputting a discharge restart command signal when the supplied current becomes equal to or less than a reference value; The discharge switch when the discharge stop command signal is generated by the shut-off state, discharge resuming instruction signal can be formed by a discharge switch control circuit for a discharge switch in a conductive state when an error occurs.

The discharge stop command circuit can be constituted by a circuit for outputting a discharge stop command signal when the discharge current of the ignition energy storage capacitor reaches a peak value.

[0011]

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 having a high polarity is induced in the primary coil of the ignition coil so as to keep the current flowing until then. Since this voltage is applied to the damper diode, the primary current of the ignition coil continues to flow through the diode. On the secondary side of the ignition coil, 2
A secondary discharge current flows, which is approximately proportional to the current flowing through the damper diode. Therefore, the secondary discharge current can be estimated by detecting the current flowing through the damper diode. When the discharge switch is turned on again when the current flowing through the damper diode falls below the reference value (when the secondary discharge current falls below the predetermined value), the charge remaining in the ignition energy storage capacitor is reduced. Discharge occurs in the primary coil of the ignition coil, and an induced voltage with a fast rise is generated again on the secondary side of the ignition coil.
When the discharge of the capacitor is stopped again when the discharge current of the capacitor reaches the set value, a high voltage is induced in the primary coil of the ignition coil, and the current flows through the damper diode. These operations can be repeated until the charge of the ignition energy storage capacitor is exhausted,
By repeating these operations, a secondary voltage having a fast rise can be repeatedly generated, and the duration of the secondary current can be extended.

In carrying out the above method, it is desirable to stop the discharge of the ignition energy storage capacitor when the discharge current reaches a peak. That is, until the discharge current of the ignition energy storage capacitor reaches the peak, the secondary electromotive force of the ignition coil increases with an increase in the temporal change rate of the discharge current. Since the change in the discharge current hardly contributes to the secondary electromotive force, it is sufficient to discharge the ignition coil until the discharge current reaches a peak.

Although the conventional capacitor discharge type ignition device is also provided with a damper diode, the above effect cannot be obtained because the ignition energy storage capacitor is conventionally discharged at a stroke. . That is, since the rising portion of the discharge current contributes to the secondary electromotive force of the ignition coil, when the capacitor is discharged at a stretch, a secondary voltage which rises once at the beginning of the discharge is induced once. In addition, the damper diode merely acts to short-circuit the voltage induced in the primary coil when the discharge of the capacitor is completed, and to continue the secondary discharge current for a short time.

On the other hand, when the discharge of the capacitor is performed in a plurality of times as in the present invention, the duration of the secondary discharge current is lengthened while repeatedly inducing the secondary voltage having a rapid rise. Therefore, the ignition performance can be remarkably improved as compared with the conventional device.

[0015]

FIG. 1 shows an embodiment of the present invention, in which 1 is an ignition coil having one end of a primary coil 1a grounded, and 2 is a non-ground side terminal of the primary coil 1a of the ignition coil. An ignition energy storage capacitor, one end of which is connected to
Reference numeral 3 denotes an ignition plug attached to a cylinder of an engine (not shown) and connected to a secondary coil 1b of the ignition coil.

Reference numeral 5 denotes a battery, and reference numeral 6 denotes a booster circuit (DC-DC converter) for boosting the output voltage of the battery 5.
The booster circuit 6 includes a pulse oscillating circuit 601 driven by the battery 5 to generate a rectangular pulse, and a transformer 6
02 and one of the transformers 602
Field effect transistor (F) connected in series to the secondary coil
ET) 603, and the voltage of the battery 5 is applied to both ends of a series circuit of the primary coil of the transformer 602 and the FET 603. The output of the oscillation circuit 601 is supplied to the gate of the FET through the resistor 604, and the oscillation output of the oscillation circuit 601 controls ON / OFF of the FET. Transformer 6
02 is applied to both ends of the series circuit of the capacitor 2 and the primary coil of the ignition coil via the diode 7, and the secondary coil of the transformer 602 → the diode 7 → the capacitor 2 → the primary coil of the ignition coil 1 → Transformer 602
, A capacitor charging circuit is configured.

Reference numeral 8 denotes a signal source for outputting a signal Vs containing information for determining the ignition timing of the engine. The signal source includes a generator coil provided in a magnet generator mounted on the internal combustion engine, an engine coil, and the like. A signal coil or the like provided in a signal generator that outputs a signal in synchronization with the signal generator is used. The output of the signal source 8 is input to an ignition timing control device 9. The output terminal of the ignition timing control device 9 has a resistor 1 connected to the base of a PNP transistor 10 whose emitter is connected to the positive terminal of the battery.
1 are connected. The ignition timing control device 9 calculates the ignition timing at each rotational speed of the engine by using the output of the signal source 8 as an input, and adds the potential V of the output terminal to the calculated ignition timing.
i ′ is set to zero level (ground level),
Apply a base current to Therefore, the transistor 10 becomes conductive at the time of ignition, and applies an ignition signal Vi to a discharge switch described later. An ignition signal generating device 1 includes a signal source 8, an ignition timing control device 9, a transistor 10, and a resistor 11.
2 are configured.

Incidentally, the ignition timing control device 9 may be constituted by an electronic circuit or a microcomputer. In some cases, the ignition timing control device 9 is omitted, and the ignition signal generation device 12 is constituted by the signal source 8 alone.

In many cases, the signal source 8 includes a signal generator having a built-in signal coil and a permanent magnet for generating a magnetic flux linked to the signal coil, and an outer peripheral portion or a boss of a rotor yoke of a magnet rotor. And a reluctor (inductor) that is provided in a part and changes a magnetic flux linked to the signal coil when the signal coil is opposed to the signal generator to induce a signal voltage in the signal coil. In some cases, a signal generator provided completely separately from the signal generator may be used. Also recently,
Using a Hall IC instead of a signal coil,
In some cases, a signal is generated by detecting a change in magnetic flux.

The other end of the capacitor 2 is connected to the drain of an FET 13 constituting a discharging switch, and the source of the FET is grounded through a current detecting resistor 14 having a sufficiently small resistance. The emitters of the PNP transistors 15 and 16 are commonly connected to the non-ground side terminal of the current detecting resistor 14, and a diode 17 whose cathode is directed to the emitter side of the transistor 15 is connected between the emitter and the base of the transistor 15. A peak detecting capacitor 18 is connected between the base of the transistor 15 and the ground, and a resistor 19 is connected between the collector of the transistor 15 and the ground. The base of the transistor 16 is the transistor 15
, And the collector of the transistor 16 is connected via a resistor 20 to the base of an NPN transistor 21. The emitter of the transistor 21 is grounded, and the collector is connected via a resistor 22 to the PNP transistor 2.
3 connected to the base. The emitter of the transistor 23 is connected to the positive terminal of the battery 5 and the collector is connected to one end of the resistor 24. A capacitor 25 and a resistor 26 are connected in parallel between the other end of the resistor 24 and the ground, and the voltage across the capacitor 25 is input to a non-inverting input terminal of a comparator 27. The inverting input terminal of the comparator 27
A set voltage Vr obtained by dividing the voltage of the battery 5 by a voltage dividing circuit including resistors 28 and 29 is input. The output terminal of the comparator 27 is connected to the base of the NPN transistor 30 whose emitter is grounded, and the collector of the transistor 30 is connected to the gate of the FET 13. The output terminal of the comparator 27 is connected to the positive terminal of the battery 5 through the resistor 31.

A damper diode 32 is connected in parallel with the primary coil of the ignition coil. This damper diode 32 is connected to the ignition energy storage capacitor 2.
Is connected in such a direction that a voltage induced in the primary coil 1a is applied in the forward direction when the discharge of the current is stopped, and a current detecting resistor 33 is connected in series with the diode 32. The connection point between the resistor 33 and the diode 32 is connected through a resistor 34 to the base of a PNP transistor 35 whose emitter is grounded, and the collector of the transistor 35 is connected through a resistor 36 to the base of a PNP transistor 37. The emitter of the transistor 37 is connected to the positive terminal of the battery 5, and the collector is connected to the non-inverting input terminal of the comparator 27 through the resistor 38. In the present embodiment, when the discharge current of the ignition energy storage capacitor 2 reaches a predetermined value, the resistors 14, 19, 20, 22, and 24, the transistors 15, 16, 21, 23, and the capacitor 18 cause the discharge current to reach a predetermined value. A discharge stop command circuit 41 that outputs a discharge stop command signal is configured. The resistance 3
The discharge restart command circuit 42 outputs a discharge restart command signal when the current supplied to the damper diode 32 becomes equal to or less than the reference value.

Further, a comparator 27 and resistors 28, 29, 3
1 and the transistor 30 constitute a discharge switch control circuit 43. The gate of the FET 13 is connected to the collector of the transistor 10 via the resistor 44.

In the above embodiment, the ignition energy storage capacitor 2 is charged to the polarity shown in FIG. 2 through the diode 7 with the output voltage of the booster circuit 6, and the terminal of the capacitor 2 as shown in FIG. The voltage Vc gradually increases. Note that Vc in FIG.
The potential of the connection point with T13 is shown.

The signal source 8 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, the signal Vs2 is set to reach the threshold level at the minimum advance position, and the ignition timing control device 9 receives these signals. The transistor 10 is turned on at the ignition timing of the engine, and the ignition signal Vi is output through the transistor 10 as shown in FIG. When the ignition signal Vi rises, the FET 13 conducts, and the electric charge of the capacitor 2 is transferred to the primary coil 1 of the ignition coil 1.
a is discharged. When the capacitor 2 discharges, FIG.
As shown in (C), a detection voltage Vd1 (about 1 to 4 V) proportional to the discharge current appears at both ends of the resistor 14. With this detection voltage Vd1, a current flows from the emitter of the transistor 15 to the peak detection capacitor 18 through the base,
Transistor 15 conducts. While the transistor 15 is conducting, the transistor 16 is kept off. After a predetermined time (about 5 μsec) has elapsed after the start of the discharge, the discharge current reaches a peak. When the discharge current reaches a peak, charging of the capacitor 18 stops. At this time, the potential of the base of the transistor 15 becomes substantially equal to the potential of the emitter, so that the base current of the transistor 15 becomes zero and the transistor 15 is turned off. As a result, the transistor 16 conducts, and a base current is supplied to the transistor 21 through the resistor 20. As a result, the transistors 21 and 23 become conductive, and the discharge stop command signal Vfs is output from the battery 5 through the transistor 23 and the resistor 24. By this discharge stop command signal, the capacitor 25
Is charged. Since the discharge stop command signal Vfs is set higher than the set voltage Vr, the potential of the output terminal of the comparator 27 becomes high. As a result, the transistor 30 becomes conductive and the gate of the FET 13 is grounded.
3 is turned off, and discharging of the capacitor 2 is stopped.
When the FET 13 is turned off, the electric charge of the capacitor 18 is discharged through the diode 17 and the resistor 14. When the discharge of the ignition energy accumulating capacitor 2 is stopped, an electromotive force having a polarity to keep the current flowing therethrough is generated in the primary coil 1a of the ignition coil. A current flows through the use resistor 33. Therefore, both ends of the resistor 33 are
As shown in (D), a voltage Vd2 proportional to the current flowing through the diode 32 is generated. While the voltage Vd2 exceeds the predetermined value, the transistors 35 and 37 are conducting, so that the discharge from the battery 5 to the comparator 27 through the transistor 37 and the resistor 38 is substantially equal to the discharge stop command signal Vfs. A stop command signal is provided. Therefore, the transistor 30 maintains the conductive state, and the FET 13 maintains the cutoff state. When the current flowing through the diode 32 falls below a predetermined reference value and the voltage Vd2 falls below the reference value,
The transistors 34 and 37 are turned off. In this embodiment, the zero output of the transistor 37 becomes the discharge restart command signal. That is, when the transistor 37 is turned off, the charge of the capacitor 25 is discharged through the resistor 26, and the input voltage of the non-inverting input terminal of the comparator 27 becomes lower than the set voltage Vr. At this time, the output of the comparator 27 becomes low level, and the transistor 30 is turned off. Therefore, when the ignition signal Vi is given, the FET 13 conducts again, and the discharge of the capacitor 2 is restarted. Thereafter, the same operation as described above is repeated, and as long as the ignition signal Vi is given, FIG.
As shown in FIG. 2C, the capacitor 2 repeatedly discharges at a predetermined time interval, and every time the discharge of the capacitor 2 stops, a current flows through the damper diode 32 as shown in FIG. The current supplied to the damper diode 32 is proportional to the secondary discharge current of the ignition coil. Further, the potential Vc at the connection point between the capacitor 2 and the FET 13 gradually decreases every time discharge is performed as shown in FIG.

As described above, if the discharge of the capacitor is performed in a plurality of times, the duration of the secondary discharge current can be lengthened while repeatedly inducing the secondary voltage having a fast rise. In addition, the ignition performance can be improved. The number of turns of the primary coil of the ignition coil may be 50 to 80 turns, similar to that used in a general capacitor discharge type ignition device, so that it is not necessary to use a large ignition coil.

Repetitive discharge of the ignition energy storage capacitor is possible as long as the charge remains in the capacitor. By controlling the time width of the ignition signal Vi output from the ignition signal generator 12, the discharge of the capacitor can be performed. Can be controlled (duration of secondary discharge current).

In the above embodiment, the discharge stop command circuit 41 is configured to output a discharge stop command signal when the discharge current reaches a peak. However, the discharge stop command signal is detected by detecting the peak of the discharge current. Is not limited to those shown in the above embodiments, and in the present invention, various circuits that detect a peak of a current and output a signal may be used as a discharge stop command circuit. it can.

Also, the discharge stop command circuit does not necessarily need to be a circuit that generates a discharge stop command signal when the discharge current reaches a peak, and outputs the discharge stop command signal when the discharge current reaches a predetermined value. A circuit that generates the signal may be used.

In the above embodiment, the discharge switch is FE
Although configured by T13, another switch element such as a transistor (which can be forcibly turned off by applying a predetermined signal to the control terminal) may be used.

In the above embodiment, the FET 603 is used as a switch element for turning on / off the primary current of the booster circuit 6. However, this switch may be any switch capable of turning on / off the primary current of the transformer. It can be replaced with another switch element.

In the above embodiment, the ignition signal generator 12
Has a signal source 8 and an ignition timing control device 9, but the configuration of the ignition signal generation device is arbitrary. For example, the ignition signal may be output directly from the signal source 8 or through a waveform shaping circuit. In the above embodiment, DC-
Although the ignition energy storage capacitor is charged using the DC converter, the present invention can be applied to the case where the ignition energy storage capacitor is charged by the output of the exciter coil provided in the magnet generator.

When igniting an engine that requires a longer secondary discharge current only in a predetermined rotation region, for example, during idling, a discharge restart command signal is generated only in a low rotation speed region and a high rotation speed is generated. In the region, the discharge restart command signal may not be generated. To do so, for example, a trigger signal is generated from the ignition timing control circuit 9 when the rotation speed exceeds a set value, and this trigger signal is given to the transistor 35, thereby forcibly turning on the transistors 35 and 37. What is necessary is just to hold | maintain a conduction state.

As described above, in the case where the generation of the discharge restart command signal is stopped in the high rotation speed region and the discharge of the ignition energy storage capacitor is performed only once, the ignition energy is maintained even after ignition. Since the charge remains in the storage capacitor 2, the secondary voltage of the transformer of the DC-DC converter does not become zero. Therefore, the current flowing to the primary side of the transformer can be reduced, and heat generation in the transformer 602 and the control circuit for the primary current can be suppressed.

Even when the discharge of the ignition energy storage capacitor is repeated a plurality of times, the load on the DC-DC converter can be similarly reduced if the capacitor is not completely discharged.

In the above embodiment, the discharge stop command circuit 41
, A discharge stop command signal is continuously generated from the discharge restart command circuit 42 to keep the discharge switch (FET 13) in the cut-off state. However, this is not always necessary. There is no. For example, when the discharge current of the ignition coil energy storage capacitor reaches a predetermined value, a discharge stop command signal is continuously generated from the discharge stop command circuit 41, and when the current supplied to the damper diode falls below the reference value. The discharge switch 13 may be turned on again by stopping the generation of the discharge stop command signal in response to the discharge restart command signal generated from the discharge restart command circuit.

[0036]

As described above, according to the present invention, it is possible to obtain a characteristic that the secondary voltage rises quickly and the duration of the secondary discharge current is long without increasing the number of turns of the primary coil of the ignition coil. be able to.

Further, according to the present invention, there is an advantage that the duration of the secondary discharge current can be easily controlled by controlling the time width of the ignition signal.

Further, in the present invention, since the ignition energy storage capacitor does not have to be completely discharged, when a DC-DC converter is used as a charging power source for the capacitor, the secondary voltage of the transformer of the converter should not be reduced to zero. Therefore, there is an advantage that the primary current of the transformer can be suppressed and the heat generation in the transformer can be suppressed low.

[Brief description of the drawings]

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

2 (A) to 2 (E) are waveform diagrams showing voltage waveforms at various parts in the embodiment of FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ignition coil, 2 ... Ignition energy storage capacitor, 3 ... Ignition plug, 5 ... Battery, 6 ... Boost circuit, 7
... Diode, 8 ... Signal source, 9 ... Ignition timing control device, 1
2: ignition signal generator, 13: FET (discharge switch), 41: discharge stop command circuit, 42: discharge restart command circuit, 43: discharge switch control circuit.

Claims (3)

(57) [Claims] 1. An ignition energy storage capacitor is charged to one polarity, and the charge of the ignition energy storage capacitor is discharged through a primary coil of an ignition coil at an ignition timing of an internal combustion engine 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, a damper diode is connected in parallel to a primary coil of an ignition coil, and after starting discharge of the ignition energy storage capacitor, The process of stopping the discharge of the capacitor when the discharge current reaches the set value and the process of restarting the discharge of the capacitor for storing the ignition energy when the current flowing through the damper diode becomes a predetermined value or less are repeated. A method for igniting a capacitor discharge internal combustion engine, comprising: 2. An ignition energy storage capacitor provided on a primary side of an ignition coil, a capacitor charging circuit for charging the ignition energy storage capacitor to one polarity, and generating an ignition signal at an ignition timing of an internal combustion engine. An ignition signal generator, and a discharge switch that conducts when the ignition signal is supplied and discharges the charge of the ignition energy storage capacitor to the primary coil of the ignition coil.
A capacitor discharge type internal combustion engine igniter comprising: a damper diode connected in parallel to a primary coil of the ignition coil; a discharge stop command signal when a discharge current of the ignition energy storage capacitor reaches a predetermined value. A discharge stop command circuit that detects a current flowing through the damper diode and outputs a discharge restart command signal when the current becomes equal to or less than a reference value. A discharge switch control circuit for turning off the discharge switch when the discharge switch occurs and turning on the discharge switch when the discharge restart command signal is generated. Engine ignition device. 3. The discharge stop command circuit according to claim 2, wherein the discharge stop command circuit is configured to output the discharge stop command signal when a discharge current of the ignition energy storage capacitor reaches a peak value. A igniter for a capacitor discharge type internal combustion engine according to claim 1.