JPS6316868Y2 - - 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.

Therefore, in the ignition timing control device for an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 57-359, the ignition timing change characteristic with respect to the change in engine speed is not proportional and is expressed, for example, as a line graph. However, in this conventional device, the quick response to engine speed fluctuations was not necessarily sufficient.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an engine ignition timing control device that can quickly respond to and determine a desired ignition timing even if the engine speed fluctuates drastically.

The ignition timing control device according to the present invention generates two sawtooth waves that are synchronized with each other and have different slopes between the most advanced and the latest ignition positions in each engine cycle, and the sawtooth wave with the larger slope is generated before the sawtooth wave with the larger slope. An edge riser is provided and at least two slopes are provided to trigger the ignition each time its level exceeds the level of the other sawtooth wave.

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

An example of the ignition timing control device according to the present invention as described above is shown in FIG.
is an engine whose ignition timing should be controlled (not shown)
A generating coil of a generator rotated by 1
1 is a rectifier diode, 12 is the generator coil 1
The ignition power supply capacitor 13 is charged via the diode 11 by the generated voltage of 0, and the thyristor 13 is made conductive via a gate circuit to be described later. A spark is generated in the ignition plug 15 via the secondary winding 14-2. Also,
The diode 18 is a diode for preventing backflow from the external terminal 21, and the 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 a timing pulse from the pulser coil 20, and is a control circuit section of the above-mentioned positive and negative waveforms. a second sawtooth wave generation circuit that generates a second sawtooth voltage having a slope angle and peak value greater than the first sawtooth voltage between timing pulses; A comparator that generates an on signal from when the difference between the two reaches a predetermined value to the negative timing pulse is a trigger signal that supplies a trigger signal to the gate of the thyristor 13 by the output of the comparator. The generation circuit is a driving power supply section of the control circuit section, and is an inhibition circuit that prohibits generation of a trigger signal within a predetermined time from the negative timing pulse generated from the pulser coil 20. The power supply section includes a diode 36 that rectifies the output voltage of the generator coil 10, a capacitor 38 that is charged via a resistor 37 by the rectified output, and the capacitor 38.
It is formed by a constant voltage element 39 for constant voltage charging. Next, in the first sawtooth wave generation circuit, 24 is a capacitor that is charged with the required time constant with a resistor 25 using the charging voltage of the capacitor 38 as a power source, and 26 is a diode D ₁ and a resistor connected between both ends of the capacitor 24. Transistors 27 and 28 are connected through transistors 27 and 28. Transistor 26 becomes conductive due to the negative timing pulse of pulser coil 20 synchronized with engine rotation due to the presence of diode 34, and together with resistor 31 and capacitor 32 constitutes a discharge circuit for 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 form 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 voltage dividing point of the voltage divider 43 and 44. Charge the battery 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. On the other hand, the capacitor 80 has a resistor 81 connected in parallel with the capacitor 41, and is charged by the power supply voltage that passes through the resistor 81, the diode 42, and the switch transistor 71 under a time constant determined by the resistor 81 and its own capacitance. The voltages across capacitors 44 and 80 are summed by a summing circuit consisting of diodes D ₁ and D ₂ and supplied to the comparator circuit as a second sawtooth wave.

The comparison circuit is formed by a transistor 51, the emitter of which is connected to the output terminal (point G) 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 amplification 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 from the capacitor 41 and is turned on (conducted).

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, positive and negative timing pulses are emitted as shown in FIG. 2A. 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. 2B. 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, the output voltage of the power supply section is applied to the capacitor 41 via the diode 42, and the voltage across the capacitor 41 becomes approximately the power supply voltage as shown in FIG. 2C. At the same time, the transistor 45 also becomes conductive to charge the capacitor 46, but the initial charging current of the capacitor 46 is limited by the voltage divided by the voltage dividing circuits 43 and 44. The voltage will be lower than that of capacitor 41. Therefore, the charge in the capacitor 41 is transferred to the capacitor 46 via the resistor 47, and the voltage across the capacitor 46 gradually increases from the rising edge of the leading edge as shown in FIG. 2D. On the other hand, the capacitor 80 is charged at the same time as the capacitor 40, but due to the presence of the resistor 81, the voltage across both ends gradually increases at a predetermined time constant, as shown in FIG.
This results in a sawtooth wave as shown in . This sawtooth wave and the sawtooth wave generated at both ends of the capacitor 46 are connected to the diode.
They are added via D ₁ and D ₂ to form a second sawtooth wave as shown in FIG. 2F. This second sawtooth wave has a leading edge rising portion and a different slope.

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 it is discharged by a negative timing pulse, the voltage across the capacitor 24 increases with a time constant determined by the resistor 25 and the capacitor 24, as shown in FIG. 2G. This results in a first sawtooth wave like this.

In the operation of the control circuit section as described above, when the second sawtooth voltage (FIG. 3F) exceeds the first sawtooth voltage (FIG. 3G), 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, the relationship between the first sawtooth wave and the second sawtooth wave will be considered with reference to FIG. In this figure, the second sawtooth wave is shown by a solid line, and as the engine speed increases, the periods of the first and second sawtooth waves become shorter, but their slopes remain unchanged. Therefore, if the second sawtooth wave is fixed, as the engine speed increases, the first sawtooth wave will change to the dashed line,
When the slope changes as shown by the two-dot chain line, the three-dot chain line, and the broken line, it can be considered that the same state occurs. Therefore,
As is clear from this figure, the engine speed, for example
If it is less than N ₁ and the second sawtooth does not reach the first sawtooth, the ignition timing will be at the position of the negative timing pulse, ie, the latest ignition timing.

Next, if the engine speed exceeds _N1 and reaches _N2 , and the first sawtooth wave is represented by a two-dot chain line, the ignition timing is gradually advanced, and the engine speed further increases until N2. N ₁ when in the range of ₂ to N ₃
The ignition timing advances at a larger rate of change than when it is in the range of N2 to _N2 , and when the engine speed exceeds _N3 , the presence of the rising edge of the leading edge of the second sawtooth wave causes the engine speed to change. Regardless, the ignition timing is maintained at the most advanced ignition timing.

As is clear from the above, according to the present invention, sawtooth waves of two different waveforms are generated simultaneously, the instantaneous values of both waves are compared, and each time one exceeds the other, the ignition trigger is triggered. The ignition timing control device can set the ignition timing quickly in response to fluctuations in engine speed, and is suitable for use in setting the ignition timing of engines with large fluctuations in engine speed, such as in-vehicle engines. is obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIGS. 2 and 3 are waveform diagrams showing voltage operation waveforms of each part of the circuit in FIG. 1, and FIG. 4 is an ignition timing control device according to the present invention. 3 is a graph showing the ignition timing control characteristics of 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 unit, 10...Generating coil, 20...
...Pulsa coil.

Claims (1)

[Claims for Utility Model Registration] (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 device comprising: pulse generating means for generating first and second timing pulses at the most advanced ignition angle position and the latest ignition angle position defining a predetermined ignition timing range for each cycle; a first sawtooth wave generating means for generating a first sawtooth wave, the first sawtooth wave having at least two different slopes greater than the slope of the first sawtooth wave between the first and second timing pulses; The second part has a raised edge part.
a second sawtooth wave means for generating a sawtooth wave; a comparison means for generating an on signal each time the second sawtooth wave exceeds the first sawtooth wave; and a comparison means for generating the trigger signal in response to the on signal. An ignition timing control device comprising a trigger signal generating means. (2) The second sawtooth wave generating means generates at least one additional sawtooth wave having a slope different from the basic sawtooth wave having a leading edge rising portion.
The ignition timing control device according to claim 1, characterized in that it comprises a charging circuit and an addition circuit that superimposes the additional sawtooth wave on the basic sawtooth wave.