JPS63629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an engine.

An engine's ignition timing control device adjusts the timing of supplying a high voltage pulse, or ignition pulse, to the engine's spark plug, in other words, the ignition timing according to increases and decreases in engine speed to achieve optimal combustion within the cylinder. That is.

As an example of such an ignition timing control device,
-139500 can be mentioned. This ignition timing control device advances the ignition timing in proportion to the engine speed when the engine speed is within a predetermined range, and at engine speeds below and above the predetermined range, the ignition timing is set to the latest ignition timing. ignition timing and the most advanced ignition timing.

However, with an ignition timing control device having such characteristics, sufficient engine characteristics may not be obtained, particularly in a high-speed range.

Therefore, in the ignition timing control device disclosed in Japanese Patent Application Laid-Open No. 57-49070, the ignition timing is adjusted so that the ignition advance characteristic with respect to changes in engine speed is represented by a trapezoidal or similar graph. It is.

However, in such a conventional device, the second triangular wave rises at a predetermined slope from the minimum advance position to the maximum advance position and maintains the level at the maximum advance position after the maximum advance position. A first triangular wave having a vertical rising portion at a corner position and rising at a predetermined slope from there to the minimum position is generated, and the point in time when the first triangular wave crosses the second triangular wave is set as the trigger timing.

That is, since the conventional device is configured to compare the levels of triangular waves generated in different time periods, there is a possibility that it will be greatly affected by fluctuations in the circuit power supply. Furthermore, since changes in engine speed are once replaced by changes in voltage and ignition timing is determined according to the changes in voltage, it is inherently susceptible to fluctuations in the circuit power supply.

Further, in this conventional device, the retard angle setting voltage is superimposed on the flat part of the second triangular wave, but in order to obtain this retard angle setting voltage, the predetermined voltage V ₃ and the flat part of the second triangular wave are superimposed. The level difference is inverted and amplified, and the linearity of the gain when inverting and amplifying the level difference is also a problem, and the fluctuations in the level difference due to fluctuations in the circuit power supply are amplified and effective, and the retard setting voltage is This has the disadvantage of large fluctuations.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ignition timing control device that solves the problems of the conventional example described above.

The ignition timing control device according to the present invention includes a pulse generating means that generates first and second timing pulses at the most advanced ignition angle position and the latest ignition angle position that define a predetermined ignition timing range for each engine cycle, and the second timing pulse. a first sawtooth wave generating means for generating a first sawtooth wave having the same period as the pulse; and a leading edge rising portion having a slope greater than the first sawtooth wave between the first and second timing pulses. a second sawtooth wave generating means for generating a second sawtooth wave having a second sawtooth wave; and a comparison means for generating an ON signal that continues only while the second sawtooth wave exceeds the first sawtooth wave; Trigger signal generation means for generating the trigger signal in accordance with a leading edge position of the ON signal; and inhibiting means for prohibiting supply of the ON signal to the trigger signal generation circuit within a predetermined time after generation of the second timing pulse. Consisting of

Hereinafter, an ignition timing control device according to the present invention will be explained in detail with reference to the drawings.

In the engine ignition timing control device according to the present invention, as shown in FIG.
If N is less than ₁ , the ignition timing is maintained at the first predetermined angle θ ₁ , and if the engine rotation speed is greater than or equal to the first predetermined rotation speed N ₁ and less than the second predetermined rotation speed N ₂ , the ignition timing is increased to the engine rotation speed. The engine speed is advanced according to the second predetermined speed (for example, proportionally).
If the engine speed is greater than or equal to N ₂ and less than the third predetermined rotation speed N ₃ , the second predetermined rotation speed θ ₂ is maintained, and if the engine rotation speed is greater than or equal to the third predetermined rotation speed N ₃ and less than the fourth predetermined rotation speed N ₄ , the engine Depending on the increase in rotational speed (e.g. inversely proportional)
The ignition timing is retarded, and the ignition timing is maintained at a first predetermined angle θ ₁ at engine speeds equal to or higher than the fourth engine speed N ₄ .

In short, the ignition timing control device according to the present invention relatively retards the ignition timing in a certain low speed range and a certain high speed range of the engine speed, and advances it in the middle speed range between the low speed and high speed range. In the intermediate range from low speed to medium speed and from medium speed to high speed, the ignition timing is gradually advanced or retarded.

An example of the ignition timing control device according to the present invention is shown in FIG. 2, in which 10 is a generator coil of a generator rotated by an engine (not shown) whose ignition timing is to be controlled, and 11 is a rectifier diode. , 12 is an ignition power supply capacitor that is charged via the diode 11 by the voltage generated by the generator coil 10, and 13 is a thyristor that is conductive via a gate circuit to be described later. 14 and the ignition plug 1 through its secondary winding 14-2.
5 to generate a spark. In addition, the diode 18
is a diode for preventing backflow from the external terminal 21, and diode 19 is a short-circuiting diode for short-circuiting the output when the output voltage of the generating coil 10 has a polarity opposite to that shown in the figure. The main circuit is configured above.

Next, 20 is a pulse generating coil (hereinafter referred to as a pulsar coil) that generates positive and negative (first and second) timing pulses at predetermined most advanced and delayed ignition angle positions in the engine cycle.

Further, , , , , is a control circuit section of the main circuit section, , is a first sawtooth wave generation circuit that generates a first sawtooth wave voltage in synchronization with the timing pulse from the pulser coil 20, and is a control circuit section of the main circuit section, a second sawtooth voltage having a slope greater than the first sawtooth voltage during the negative timing pulses;
The sawtooth wave generation circuit is a comparator that compares the first and second sawtooth waves (voltages) and generates an on signal from when the difference between the two reaches a predetermined value to the negative timing pulse. A trigger signal generation circuit that supplies a trigger signal to the gate of the thyristor 13 based on the output of the comparator; is a driving power supply section of the control circuit section; This is a prohibition circuit that prohibits

The power supply section includes a diode 36 that rectifies the output voltage of the generator coil 10 and a resistor 37 that uses this rectified output.
a capacitor 38 charged via the capacitor 38 and a constant voltage element 39 for charging the capacitor 38 with a constant voltage.
It is formed by Next, in the first sawtooth wave generation circuit, 24 is a capacitor that is charged with a required time constant with a resistor 25 using the charging voltage of the capacitor 38 as a power source, and 26 is a capacitor that is charged with the required time constant of the capacitor 24.
A transistor connected between both ends of the transistor 2 through a diode D ₁ and resistors 27 and 28.
6 becomes conductive due to the negative timing pulse of the pulser coil 20 synchronized with the engine rotation due to the presence of the diode 34, and together with the resistor 31 and the capacitor 32 constitutes a discharge circuit of 24.

Next, in the second sawtooth wave generation circuit, the switch transistor 71 is turned on and off in response to the on and off of the auxiliary transistor 72 which is turned on and off by the positive timing pulse from the pulser coil 20. The capacitor 41 is connected to the transistor 71
is charged via the diode 42 when is on,
The resistors 43 and 44 constitute a voltage divider that divides the driving power supply voltage, and the base of a transistor 45 is connected to the voltage dividing point of the voltage divider 43 and 44, and is made conductive by the conduction of the switch transistor 71, and the capacitor 46 is connected to the base of the transistor 45. The battery is charged to the divided voltage of the voltage divider.
Capacitors 46 and 41 are connected by a resistor 47, and capacitor 46 is charged with a time constant with resistor 47 using capacitor 41 as a power source.

The comparison circuit is formed by a transistor 51, the emitter of which is connected to the output terminal (point D) of the second sawtooth wave generation circuit, and the base connected to the output terminal (point E) of the first sawtooth wave generation circuit. The collector is also connected to a trigger signal generation circuit via a resistor 52 with the collector as a comparison output terminal.

Next, 61 and 62 are amplifying transistors, and the transistor 61 is made conductive by the output of the comparison circuit.
This makes the transistor 62 conductive.
Then, as the transistor 62 becomes conductive, the thyristor 13 is supplied with a gate current and is turned on (conductive). In addition, the trigger prohibition circuit is a diode _D2
The circuit includes a timer circuit 80 that is reset by a negative timing pulse supplied through the circuit, starts the timer, and generates a trigger prohibition pulse that continues for a predetermined period of time, and a transistor 81 that is turned on by the trigger prohibition pulse. . Note that the trigger inhibit pulse width of the timer circuit 80 is never longer than the time until the next negative timing pulse.

Next, the circuit operation of the device of the present invention will be explained with reference to FIG.

First, when the engine starts, the pulsar coil 2
From 0 onwards, positive and negative timing pulses are emitted as shown in FIG. 3A. As mentioned above, the positive and negative timing pulses are generated at the most advanced and the latest angular positions of the ignition timing in the engine cycle, in other words, the positive and negative timing pulses This defines the ignition timing variation range. On the other hand, capacitor 38
is the Zener voltage Vz of the Zener diode 39
The waveform of the voltage across the battery is maintained almost constant as shown in FIG. 3B. The positive timing pulse from the pulser coil 20 is connected to the resistor 31a.
The signal is supplied to the base of the transistor 72 through the parallel circuit of the capacitor 32a and turns on the transistor 72, and at the same time turns on the transistor 71 as well. When the transistor 71 is turned on by a positive timing pulse, the output voltage of the power supply section is applied to the capacitor 41 via the diode 42.
The voltage across the terminal becomes approximately the power supply voltage as shown in FIG. 3C. At the same time, transistor 45 also becomes conductive and charges capacitor 46;
The initial charging current of capacitor 46 is limited by the voltage divided by voltage dividing circuits 43 and 44, and the initial voltage across capacitor 46 is lower than that of capacitor 41. Therefore, the charge stored in the capacitor 41 is transferred to the capacitor 46 via the resistor 47, and the voltage across the capacitor 46 gradually increases as shown in FIG. 3D.

Then, the negative timing pulse is applied to the pulser coil 2.
When supplied from 0, diode 34 and resistor 2
8 and 31, the emitter current of the transistor 26 decreases, and the transistor 26 becomes conductive, passing through the diode D ₁ and the resistor 27 to the capacitor 24.
At the same time, the transistor 51 is made conductive and the capacitors 41 and 46 are also discharged. Since the power supply voltage is always applied to the capacitor 24,
After being discharged with a negative timing pulse, it is charged with a time constant determined by the resistor 25 and the capacitor 24, and the voltage across the capacitor 24 gradually rises to form a sawtooth wave as shown in FIG. 3E.

On the other hand, the timer circuit 80 supplies the base of the transistor 81 with a trigger inhibit pulse that continues for a predetermined period of time starting from the negative timing pulse, as shown in FIG. 3F.

In the operation of the control circuit section as described above, when the second sawtooth voltage (D in FIG. 3) exceeds the first sawtooth voltage (E in FIG. 3), the transistor 51 is turned on, and then the transistor 62 is turned on. The trigger signal is then supplied to the resistors 16 and 17, turning on the thyristor 13, discharging the capacitor 12, and igniting it.

Therefore, the ignition timing is determined by the point in time after the generation of the negative timing pulse when the difference between the first and second sawtooth voltages reaches a predetermined value (for example, zero) (in this case, the predetermined value is the base-emitter voltage of the transistor 51). It is determined. Here, since the slope of the second sawtooth wave is larger than that of the first sawtooth wave, as the engine speed increases beyond the predetermined speed _N1 , the voltage of the second sawtooth wave becomes higher than that of the first sawtooth wave. The time it takes to reach the wave voltage becomes earlier, and the ignition timing becomes earlier, that is, the ignition timing is advanced. However,
The second sawtooth wave voltage is a pulse waveform having a leading edge rising part that immediately increases by a predetermined voltage at the same time as the negative timing pulse is generated, and when the predetermined engine rotation speed _N2 is exceeded, the second sawtooth wave voltage is generated simultaneously with the generation of the negative timing pulse. Since the second sawtooth wave exceeds the first sawtooth voltage, a trigger signal is provided to the thyristor simultaneously with the negative timing pulse. In this state, the most advanced ignition timing is obtained, and this state continues until the predetermined rotation speed _N3 .
When the engine speed increases beyond the predetermined speed _N3 , when the transistor 81 is in the on state, the second sawtooth voltage exceeds the first sawtooth voltage, the transistor 51 is turned on, and the transistor 81 is turned on. As long as it is on, the transistor 61 is not turned on and the thyristor 13 is not triggered, and at the end of the trigger inhibit pulse, the transistor 61 is turned on and the thyristor 13 is triggered. thus,
As the engine speed increases, the ignition timing is retarded, but since the trigger prohibition pulse from the timer circuit 80 is limited to the time when the next negative timing pulse is generated, if the engine speed exceeds the predetermined speed _N4 . Ignition will occur at the latest ignition angle.

Note that it is clear that the timer circuit 80 can be realized using a capacitor charging/discharging circuit. In addition, the device of the present application is configured to cut off the leading edge of the on signal using a fixed timer, and is configured to directly reflect fluctuations in the engine rotation itself in the trigger timing, so there is little effect from fluctuations in the circuit power supply voltage. The circuit configuration is simple.

The temporal relationship between the first sawtooth voltage, the second sawtooth voltage, the trigger inhibit pulse, and the trigger pulse according to the change in engine speed as described above is expressed as
As shown in the figure. That is, Fig. 4 A, B, C, and D are as follows.
A first sawtooth voltage, a second sawtooth voltage, a trigger inhibit pulse, and a trigger pulse are shown, respectively. In Fig. 4B, the waveform indicated by the solid line corresponds to the predetermined rotational speed.
When the engine speed is N ₁ or less, the dashed line is the predetermined engine speed N ₁ to N ₂ , the one-dot chain line is the predetermined engine speed N ₂ to N ₃ , and the two-dot chain line is the predetermined engine speed N ₃ to N 2. The case of engine speed of _N4 is shown respectively.

In the engine ignition timing control device according to the present invention, the first and second sawtooth waves are generated simultaneously and the rising edge of the on signal continues only while one of the waves exceeds the other. Both sawtooth waves are generated simultaneously and in parallel, so even if there is a voltage fluctuation in the circuit power supply, the voltage level of both sawtooth waves will only shift in the same way, and the relative There is no significant effect on the size relationship. Therefore, the system according to the present invention is excellent as an on-vehicle engine ignition timing control device driven by an on-vehicle power source whose voltage fluctuates.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the ignition timing characteristics of the ignition timing control device according to the present invention, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIGS.
FIG. 3 is a waveform diagram showing voltage operation waveforms of various parts of the circuit shown in the figure. Explanation of symbols of main parts, ...main circuit section, ...
...first sawtooth wave generation circuit, ...second sawtooth wave generation circuit, ...comparator, ...trigger signal generation circuit, ...power supply section, ...trigger prohibition circuit, 10
...Generating coil, 20...Pulsa coil.

Claims (1)

[Claims] 1 An ignition timing control device that supplies a trigger signal to an ignition circuit that supplies a high voltage pulse to an ignition coil for driving an ignition plug of an engine in response to a trigger signal, the ignition timing control device determining a predetermined ignition timing range for each engine cycle. Pulse generating means for generating first and second timing pulses at the ignition angular position and the latest ignition angular position, and first sawtooth wave generating means for generating a first sawtooth wave having the same period as the second timing pulse. and a second sawtooth wave generating means for generating a second sawtooth wave having a slope greater than that of the first sawtooth wave and having a leading edge rising portion between the first and second timing pulses; comparison means for generating an ON signal that continues only while the second sawtooth wave exceeds the first sawtooth wave; and trigger signal generation means for generating the trigger signal in accordance with the leading edge position of the ON signal. An ignition timing control device comprising: prohibiting means for prohibiting supply of the on signal to the trigger signal generation circuit within a predetermined time after generation of the second timing pulse.