JPH03189367A - Ignition device for capacitor discharge type internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent consumption of surplus energy by providing a command signal generating circuit to output an operation command signal when a capacitor voltage detecting signal is below a voltage set signal through comparison of the capacitor voltage detecting signal with the voltage set signal and output a stop command signal when exceeding. CONSTITUTION:When a drive pulse Vp is fed from a drive pulse feed control circuit 28 to a switch element 10, a converter circuit 8 is operated to start charge of a capacitor 4 for accumulating ignition energy by means of an output therefrom. When the charge voltage of capacitor 4 is increased to a value higher than a value enough for ignition, a detecting signal Vcd for a charge voltage exceeds a set signal Vr1, and a stop command signal is generated from a command signal generating circuit 27. In which case, since the circuit 28 stops the feed of a driven pulse to the circuit 8, the increase of the charge voltage of the capacitor 4 is stopped. Since the signal Vr1 is set to a value responding to the intensity of the charge voltage of the capacity 4 required for current ignition at each ignition timing, the charge voltage of the capacitor 4 is properly controlled according to an ignition timing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capacitor discharge type ignition device for an internal combustion engine.

[Prior Art] As is well known, a capacitor discharge type ignition system for an internal combustion engine drains the charge of the ignition energy storage capacitor when it is electrically connected to the ignition energy storage capacitor provided on the primary side of the ignition coil. It is comprised of a thyristor provided to cause discharge to the primary side, and an ignition timing control circuit that provides a trigger signal to the thyristor at the ignition timing of the internal combustion engine.

When driving this type of ignition device using a battery as a power source, a DC-DC converter is used that continues the primary current of the transformer and boosts the battery voltage by a switching element that is turned on and off by the drive pulse obtained from the oscillator. A capacitor is charged by the output of the converter.

In a capacitor discharge type ignition device, the output voltage obtained on the secondary side of the ignition coil is approximately proportional to the charging voltage of the ignition energy storage capacitor.

In a conventional capacitor discharge type ignition system using a DC-DC converter, as shown in Japanese Patent Application Laid-Open No. 1-117984, the output voltage of the converter is detected and the detected voltage is compared with a certain reference voltage. The charging voltage of the ignition energy storage capacitor is limited to a substantially constant value regardless of the ignition timing.

[Problems to be Solved by the Invention] Generally, in a piston type internal combustion engine, the ignition timing is advanced in a medium to high speed range in order to obtain desired characteristics of the engine. In addition, for two-cycle engines for motorcycles, etc., Fig. 2 (
As shown in A), after advancing the ignition timing θi in the medium speed range, the ignition timing θi may be delayed again in the high speed range.

When ignition occurs during the engine's compression stroke in a piston-type internal combustion engine, the cylinder pressure at the instant of ignition is lower as the ignition timing advances, and conversely increases as the ignition timing is delayed. Generated voltage) V2
As shown in FIG. 2(B), s is low when the ignition timing is advanced, corresponding to the ignition timing shown in FIG. 2(A).
On the other hand, it becomes higher when the ignition timing is delayed.

On the other hand, in a capacitor discharge type ignition device, as is well known, the voltage generated on the secondary side of the ignition coil is approximately proportional to the charging voltage of the ignition energy storage capacitor connected to the primary side. Therefore, the charging voltage Vcs of the ignition energy storage capacitor is required to supply the required ignition voltage to the ignition plug.
As shown in FIG. 2(C), is low when the ignition timing θi is advanced, and conversely becomes high when the ignition timing θ1 is delayed.

In conventional ignition systems, the charging voltage of the ignition energy storage capacitor is maintained at a nearly constant value even if the ignition timing changes; The value was selected to be the highest value required when the value is highest.

Therefore, in conventional ignition systems, when the ignition timing is advanced, excess energy is stored in the ignition energy storage capacitor than necessary, resulting in large battery power consumption and ignition coil and DC-DC converter. extra energy will be consumed. Particularly in the case of motorcycles, which are often used in the mid-speed range with advanced ignition timing, the vehicle speed is not very fast, so the ignition system does not cool down sufficiently while driving (in order to suppress temperature rise, the ignition coil or DC- There was a problem in that the DC converter had to be made large.

An object of the present invention is to provide a capacitor discharge type ignition device for an internal combustion engine that can operate efficiently without consuming excess energy.

[Means for Solving the Problem] As seen in FIG. 1 showing an embodiment of the present invention,
a DC voltage step-up converter circuit 8 having a switching element 10 that is turned on and off by a drive pulse Vp; an ignition energy storage capacitor 4 provided on the primary side of the ignition coil 1 and charged by the output of the converter circuit 8;
A thyristor 5 provided to discharge the charge of the ignition energy storage capacitor 4 to the primary coil 1a of the ignition coil 1 when conductive, and an ignition timing control circuit that applies a trigger signal Vt between the gate cathode of the thyristor 5. The present invention relates to a capacitor discharge type ignition device for an internal combustion engine, which is equipped with 19.

In the present invention, a capacitor voltage detection circuit 24 detects the charging voltage of the capacitor 4 and outputs a capacitor voltage detection signal Vcd corresponding to the charging voltage of the capacitor,
A voltage setting signal generator 20 that outputs a voltage setting signal Vrl whose magnitude changes in accordance with the ignition timing such that it becomes smaller as the ignition timing of the engine advances and becomes larger as the ignition timing is delayed; and a capacitor voltage detection signal Vcd.
is compared with the voltage setting signal Vrl, and outputs an operation command signal when the capacitor voltage detection signal is less than the voltage setting signal, and outputs a stop command signal when the capacitor voltage detection signal exceeds the set voltage signal. The circuit 27 inputs the drive pulse and the output of the command signal generation circuit 27, supplies the drive pulse to the switching element when an operation command signal is generated, and outputs the drive pulse when a stop command signal is generated. Drive pulse supply control circuit 2 that stops supply
8 was established.

[Function] In the above configuration, when the drive pulse Vp is supplied from the drive pulse supply control circuit 28 to the switching element 10, the converter circuit 8 operates and starts charging the ignition energy storage capacitor 4 with its output. Ru. capacitor 4
When the charging voltage increases and becomes equal to or higher than the value required for ignition, the charging voltage detection signal Vcd becomes equal to or higher than the setting signal Vr1, and the command signal generation circuit 27 generates a stop command signal. When this stop command signal is generated, the drive pulse supply control circuit 2
8 stops supplying the drive pulse to the converter circuit, so the charging voltage of the capacitor 4 stops rising. The setting signal Vrl is set to a value corresponding to the charging voltage of the capacitor 4 required for ignition at each ignition timing, so if the ignition timing is advanced and the capacitor charging voltage required for ignition is low. In this case, the charging voltage of the capacitor is limited to that low value, and if the ignition timing is delayed and the charging voltage of the capacitor required for ignition becomes high, the charging voltage of the capacitor becomes a high value.

In this way, since the charging voltage of the capacitor is controlled to an appropriate value according to the ignition timing, the capacitor 4 is not charged to an excessively high voltage. Therefore, unnecessary energy is not consumed in the ignition coil or converter circuit, and battery power consumption can be reduced.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention, in which 1 indicates a primary coil 1a whose one end is grounded, and a secondary coil 1a whose one end is grounded.
The ignition coil 2 has an ignition coil 2, which is a spark plug attached to a cylinder of an engine (not shown), and the output voltage of the secondary coil 1b of the ignition coil is applied to the ignition plug 2. 1
A diode 3 with its cathode facing the ground side is connected in parallel to both ends of the secondary coil 1a. One end of an ignition energy storage capacitor 4 is connected to the non-grounded terminal of the primary coil 1a, and a thyristor 5 is connected between the other end of the capacitor 4 and the ground with its cathode facing the ground.

In order to charge the ignition energy storage capacitor 4, a converter circuit 8 consisting of a converter main circuit 6 and an oscillation circuit 7 is provided. Converter main circuit 6 includes a transformer 9, a field effect transistor 10, a resistor 11, and a diode 12. One end of the primary coil of the transformer 9 is connected via a power switch 14 to the positive electrode of a battery 13 whose negative electrode is grounded, and the other end is connected to the drain of a field effect transistor 10. The source of the field effect transistor 10 is grounded, and a resistor 11 is connected between the gate and source of the field effect transistor.

One end of the secondary coil of the transformer 9 is grounded, and the anode of the diode 12 is connected to the other end of the secondary coil. In this example, the field effect transistor 10 constitutes a switching element of the converter circuit.

The oscillation circuit 7 is composed of a known unstable multivibrator composed of an operational amplifier, a resistor, and a capacitor, and outputs a rectangular wave pulse having a frequency of, for example, about 200 kHz. The output pulse V'p (FIG. 4G) of the oscillation circuit 7 is supplied to the gate of the field effect transistor 10 through the AND circuit 15 as a drive pulse Vp. The field effect transistor 10 is turned on and off by this drive pulse to continue the primary current of the transformer 9. When the primary current of the transformer 9 continues, a high voltage is induced in the secondary coil, and this voltage is rectified by the diode 12 and applied to the ignition energy storage capacitor 4. This causes capacitor 4
is charged to the polarity shown.

In order to obtain rotation angle information and speed information of an internal combustion engine, a signal generator includes a reluctor 16 that rotates in synchronization with the rotation of the engine and a signal coil 17 that induces a voltage by a change in magnetic flux that occurs as the reluctor rotates. The output of the signal coil 17 is input to an ignition timing control device 19 whose power source is a stabilized power supply circuit 18 which receives the output voltage of the battery 13 and outputs a constant voltage. The ignition timing control device 19 obtains rotation angle information and speed information from the signal coil 17, calculates the ignition timing at each rotation speed, and supplies the trigger signal V1 to the thyristor 5 at the calculated ignition timing.

In this example, as shown in FIG. 4(A), the signal coil 17 outputs a signal es of one cycle per revolution of the engine. The signal eS used in this example consists of a negative voltage esl that occurs between the maximum advance position θ1 and the minimum advance position θ2 of the engine, and a steep positive voltage e that rises at the minimum advance position θ2.
It consists of s2.

This signal es is input to the ignition timing control device 19. The ignition timing control device 19 performs a predetermined calculation based on the rotation angle information and speed information given by the signal es, and generates a trigger signal Vt (fourth (see Figure B).

The ignition timing control device 19 has various configurations depending on the ignition characteristics of the engine, but the configuration of this ignition timing control device is arbitrary in the present invention. FIG. 2(A) shows an example of the characteristics of the ignition timing θi with respect to the rotational speed N of the engine. An ignition timing control device that obtains such ignition timing characteristics is already known, as disclosed in Japanese Patent Publication No. 62-42155, for example.

The present invention also provides a voltage setting signal Vrl according to the ignition timing.
A voltage setting signal generator 20 is provided that generates a voltage setting signal. This voltage setting signal generator 20 includes a stabilized power supply circuit 1
8 as a power source, receives a signal containing information on the current ignition timing from the ignition timing control device 19, and generates a voltage setting signal Vrl whose magnitude changes depending on the ignition timing of the engine. The change in the voltage setting signal Vrl with respect to the ignition timing is as shown in FIG. 3, for example, and decreases as the ignition timing advances and increases as the ignition timing delays.

Since the ignition timing has a correlation with the rotation speed, the rotation speed information may be incorporated into the voltage setting signal generating device 20 and the voltage setting signal Vrl may be generated based on the rotation speed information. Even in this case, the voltage setting signal Vrl still decreases as the ignition timing advances and increases as the ignition timing delays.

The ignition timing control device 19 and the voltage setting signal generation device 20 can be configured by a microcomputer.

The voltage setting signal Vrl is input to the non-inverting input terminal of the comparison circuit 21. In order to detect the charging voltage of the capacitor 4, a resistor 22 is connected between the anode and cathode of the thyristor 5.
A voltage dividing circuit consisting of a series circuit of a variable resistor 23 and a variable resistor 23 is connected in parallel, and a capacitor charging voltage detection circuit 24 is constituted by this voltage dividing circuit. The capacitor charging voltage detection circuit 24 generates a capacitor voltage detection signal Vcd proportional to the charging voltage of the ignition energy storage capacitor 4 across the variable resistor 23, and this detection signal is input to the inverting input terminal of the comparison circuit 21. There is. The comparison circuit 21 compares the capacitor voltage detection signal Vcd and the setting signal Vrl, and changes the state of the output signal v1 according to the magnitude relationship between these signals. That is, the detection signal Vcd is the voltage setting signal Vr.
When Vcd≦Vrl is less than Vrl, the output signal V1
becomes high level (logical value is "1"), and the detection signal Vcd
When the voltage exceeds the voltage setting signal Vrl (when Vcd>Vrl), the output signal v1 becomes a low level (logical value is "0"). In this example, a high level signal obtained from the comparison circuit 21 is used as an operation command signal, and a low level signal obtained from the comparison circuit 21 is used as a stop command signal.

The output signal v1 of the comparison circuit 21 is input to the AND circuit 15 together with the pulse signal Vp' obtained from the oscillation circuit 7.

Further, a capacitor 25 and a resistor 26 are connected in parallel between the gate and cathode of the thyristor 5, and the voltage Vgk between the gate and cathode of the thyristor 5 is inputted to an inverting input terminal of a comparison circuit 27. A reference voltage Vr2 obtained by dividing the output voltage of the stabilized power supply circuit 18 by a voltage dividing circuit including a resistor 29 and a variable resistor 30 is input to a non-inverting input terminal of the comparison circuit 27. The comparison circuit 27 compares the voltage Vgk between the gate and cathode of the thyristor 5 and the reference voltage Vr.
2 and 2 and change the state of the output signal v2. That is, the signal V2 becomes high level (logical value "1") when Vgk≦Vr2, and becomes low level (logical value "0") when Vgk>Vr2.

In this example, a high level signal obtained from the comparison circuit 27 is used as an operation command signal, and a low level signal obtained from the comparison circuit 27 is used as a stop command signal. The reference voltage Vr2 is set lower than the trigger level of the thyristor 5, and the gate-cathode voltage V of the thyristor 5 is set lower than the trigger level of the thyristor 5.
The output of the comparison circuit 27 becomes low level before gk reaches the trigger level of the thyristor 5. The output v2 of the comparison circuit 27 is input to the AND circuit 15.

In this example, the comparator circuit 21 is a command signal generation circuit that outputs an operation command signal when the capacitor voltage detection signal is less than or equal to the voltage setting signal, and outputs a stop command signal when the capacitor voltage detection signal exceeds the set voltage signal. is configured.

Furthermore, the AND circuit 15 causes the switching element (field effect transistor 10
), and a drive pulse supply control circuit 2 that supplies drive pulses when a stop command signal is generated.
8 are made up.

Next, the operation of the above embodiment will be explained.

When the trigger signal V1 is not applied to the thyristor 5, the output V2 of the comparison circuit 27 (see FIG. 4F) is in the state of "1". In addition, when the terminal voltage of the ignition energy storage capacitor 4 is lower than the charging voltage Vcs required for ignition,
When the charging voltage detection signal Vcd is lower than the setting signal Vrl, the output Vl of the comparison circuit 21 (see FIG. 4E) is "1". At this time, the AND condition of the AND circuit 15 is satisfied every time the oscillation circuit 7 generates a pulse, so the driving pulse Vp (see FIG. 4H) is applied to the gate of the field effect transistor 10 through the AND circuit 15, The field effect transistor repeatedly turns on and off to induce a high voltage in the secondary coil of the transformer 9.

Since this voltage is applied to the ignition energy storage capacitor 4 through the diode 12, the capacitor 4 is charged to the polarity shown, and the terminal voltage Vc of the capacitor 4 rises as shown in FIG. 4(D). go.

The terminal voltage Vc of the capacitor 4 is the charging voltage V required for ignition.
The detection signal Vcd is set to reach the setting signal Vr1 when the detection signal Vcd reaches the setting signal Vr1. Therefore, when the terminal voltage Vc of the capacitor 4 becomes equal to or higher than the charging voltage VCS required for ignition, the output of the comparison circuit 21 becomes "0" and the output signal of the AND circuit 15 becomes "0".

Therefore, the field effect transistor 10 is kept in a cut-off state, the operation of the converter main circuit 6 is stopped, and the charging of the capacitor 4 is also stopped, so that the terminal voltage of the capacitor 4 is kept at the charging voltage Vcs necessary for ignition.

The ignition timing control device 19 sends a trigger signal V to the ignition timing of the engine.
When 1 is generated, the thyristor 5 becomes conductive and discharges the charge in the capacitor 4 to the primary coil of the ignition coil. As a result, a high voltage is generated in the secondary coil of the ignition coil, a spark is generated in the ignition plug 2, and the engine is ignited.

When the thyristor 5 becomes conductive and the capacitor 4 discharges, an anode current flows through the thyristor, causing a voltage drop between the gate and cathode of the thyristor, and this voltage drop charges the capacitor 25. The voltage Vgk is maintained at or above the reference voltage Vr2. Therefore, the output of the comparison circuit 27 is kept at "0", and the AND circuit 15 stops outputting the drive pulse. Therefore, the converter circuit stops operating and stops charging the capacitor 4. Even if the anode current of the thyristor 5 disappears, the charge in the capacitor 25 is discharged through the resistor 26 at a constant time constant, and the terminal voltage of the capacitor 25 remains at or above the reference voltage Vr2 for a certain time.

Therefore, the output of the comparator circuit 27 continues to be "0" for a certain period of time not only while the anode current is flowing through the thyristor 5 but also after the anode current of the thyristor becomes zero. During this time, the AND circuit 15 stops supplying the drive pulse to the field effect transistor 10 and stops the operation of the converter, so that the commutation of the thyristor 5 is reliably performed.

When the capacitor 4 discharges and its terminal voltage drops sharply, and the detection signal Vcd becomes lower than the setting signal Vrl, the comparator circuit 21
The output V1 becomes "1". Therefore, the voltage Vgk between the gate and cathode of the thyristor 5 decreases, and the reference voltage Vgk decreases.
When r2 becomes lower and the output ■2 of the comparison circuit 27 becomes "1" again, the output pulse of the oscillation circuit 7 supplies a driving pulse to the field effect transistor 10 through the AND circuit 15, so the converter starts operating again. Charging of the ignition energy storage capacitor 4 is restarted. In this way, the ignition operation is repeated.

As the ignition timing of the engine advances, the cylinder internal pressure at the time of ignition decreases, so the charging voltage of the capacitor 4 required for ignition decreases to, for example, Vcs- (see the fourth diagram). At this time, the voltage setting signal Vl output from the voltage setting signal generation circuit 20
r decreases to voltage Vlr', which corresponds to voltage Vcs-. Further, when the terminal voltage Vc of the capacitor 4 reaches the voltage Vcs-, the detection signal Vcd reaches the setting signal Vr-.

Therefore, when the ignition timing advances and the charging voltage of the capacitor 4 necessary for ignition drops to Vcs=, when the detection signal Vcd reaches the voltage setting signal Vlr', the output of the comparator circuit 21 becomes "0" and the drive pulse The output of Vp is stopped. As a result, the operation of converter main circuit 6 is stopped, and the charging voltage of capacitor 4 is maintained at Vcs-.

If the ignition timing of the engine is delayed, the cylinder internal pressure at the time of ignition increases, so the charging voltage of the capacitor 4 required for ignition increases to, for example, Vcs' (see Figure 4). At this time, the voltage setting signal Vl output from the voltage setting signal generation circuit 20
r increases to voltage Vlr' corresponding to voltage Vcs'. Further, when the terminal voltage Vc of the capacitor 4 reaches the voltage Vcs', the detection signal Vcd reaches the setting signal Vrl'.

Therefore, when the ignition timing is delayed and the charging voltage of the capacitor 4 necessary for ignition rises to Vcs', the output of the comparator circuit 21 becomes "0" when the detection signal Vcd reaches the voltage setting signal Vlr', and the drive is driven. Output of pulse Vp is stopped.

As a result, the operation of the converter main circuit 6 is stopped, and the charging voltage of the capacitor 4 is maintained at Vcs.

As described above, in the present invention, the voltage setting signal set corresponding to the capacitor voltage required for ignition is compared with the capacitor voltage detection signal at each ignition timing, and when the detection signal exceeds the voltage setting signal, Since the operation of the converter is stopped immediately, the capacitor 4 is always charged to a voltage required for ignition, and the capacitor is never charged to a voltage higher than necessary.

In the above embodiment, the output of the oscillation circuit 7 is supplied to the field effect transistor 10 (switching element of the converter) through the AND circuit 15, but the output terminal of the oscillation circuit 7 is directly connected to the gate of the field effect transistor 10. The AND circuit 15 is connected so that the oscillation circuit 7 stops generating when the output of the AND circuit 15 is "0" and starts oscillating when the output of the AND circuit 15 is "1". The oscillation of the oscillation circuit 15 may be controlled by the following.

[Effects of the Invention] As described above, according to the present invention, the charging voltage of the ignition energy storage capacitor required for ignition of the engine at each ignition timing is set to vary with the ignition timing in accordance with the magnitude of the charging voltage. The voltage setting signal is compared with the detection signal of the charging voltage of the ignition energy storage capacitor, and when the detection signal exceeds the voltage setting signal, the supply of drive pulses to the converter circuit is stopped. Therefore, the charging voltage of the ignition energy storage capacitor can be limited to the level necessary for ignition of the engine at the current ignition timing. Therefore, it is possible to prevent the ignition energy storage capacitor from being charged to an unnecessarily high voltage, and the power consumption of the power source battery can be reduced.

Furthermore, since the energy consumption in the ignition circuit can be reduced, there is an advantage that the converter circuit and the ignition coil can be made smaller, and a highly efficient capacitor discharge type ignition device for an internal combustion engine can be obtained.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing an example of ignition characteristics obtained by the embodiment of Fig. 1, and Fig. 3 is a diagram showing the ignition timing in the embodiment of Fig. 1. FIG. 4 is a diagram showing an example of the relationship between the ignition energy storage capacitor and the charging voltage setting value, and FIG. 4 is a waveform chart showing signal waveforms at various parts in FIG. DESCRIPTION OF SYMBOLS 1... Ignition coil, 2... Spark plug, 4... Ignition energy storage capacitor, 5... Thyristor, 6
...Converter main circuit, 7...Oscillation circuit, 8...
Converter circuit, 9... Transformer, 10... Field effect transistor (switching element), 13... Battery, 15... AND circuit, 17... Signal coil,
19... Ignition timing control circuit, 20... Ignition timing function voltage generation circuit, 21... Comparison circuit, 24... Capacitor charging voltage detection circuit, 28... Drive pulse supply control circuit.

Claims (1)

[Claims] A DC voltage step-up converter circuit having a switching element that is turned on and off by a drive pulse, and one of the ignition coils.
an ignition energy storage capacitor provided on the next side and charged by the output of the converter circuit; and an ignition energy storage capacitor provided on the next side so as to discharge the electric charge of the ignition energy storage capacitor to the primary coil of the ignition coil when the capacitor is electrically connected. In a capacitor discharge type internal combustion engine ignition device comprising a thyristor and an ignition timing control circuit that provides a trigger signal between a gate cathode of the thyristor, the charging voltage of the capacitor is detected and a capacitor corresponding to the charging voltage of the capacitor is set. A capacitor voltage detection circuit that outputs a voltage detection signal; and a voltage setting that outputs a voltage setting signal that changes in magnitude according to the ignition timing so that it becomes smaller as the ignition timing of the engine advances and becomes larger as the ignition timing is delayed. a signal generator; comparing the capacitor voltage detection signal with the voltage setting signal; outputting an operation command signal when the capacitor voltage detection signal is less than or equal to the voltage setting signal; and when the capacitor voltage detection signal exceeds the setting voltage signal; a command signal generation circuit that outputs a stop command signal to the switching element; and a command signal generation circuit that receives the drive pulse and the output of the command signal generation circuit as input, and supplies a drive pulse to the switching element when the operation command signal is generated to stop the switching element. An ignition device for a capacitor discharge internal combustion engine, comprising a drive pulse supply control circuit that stops supply of the drive pulse when a command signal is generated.