JPH0427388B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an internal combustion engine ignition device,
In particular, it concerns the prevention of engine overspeed.

Since high-output internal combustion engines are often operated at high rotational speeds, there is a risk that the engine will be destroyed if the engine is operated at abnormally high rotational speeds. For this reason, high-output internal combustion engines are generally equipped with an overspeed prevention function to prevent their rotation from exceeding a predetermined value.

One way to prevent this overspeed is to temporarily stop the operation of the ignition device.

The conventional device will be explained below with reference to FIGS. 1 and 2. In the figure, 1 is an ignition signal generator that generates an ignition signal according to the rotation of the internal combustion engine, and 2 is an ignition signal generator that processes the ignition signal from the ignition signal generator 1, performs waveform shaping and closing angle control, and outputs an ignition pulse. A pulse circuit, 3 is a switching circuit that responds to the ignition pulse from the ignition pulse circuit 2 to turn on and off the energization of an ignition coil 4, which will be described later, and 4 is an ignition coil having a power terminal 5 at one end for supplying electric power. , is driven by the switching circuit 3 to output the ignition voltage. 6 is a pulse generator that generates a pulse signal with a fixed time width in response to the ignition signal from the ignition signal generator 1; 7 is a pulse generator that receives the pulse signal from the pulse generator 6 and generates a level proportional to the engine speed; It is an FV converter that outputs a rotation information signal of
For example, the configuration is such that a capacitor is charged and discharged in accordance with a pulse signal from the pulse generator 6 to obtain a DC voltage at a level corresponding to the engine rotational speed at that time. 8
a rotation detector 9 which compares the levels of the rotation information signal from the FV converter 7 and outputs an ignition stop pulse in synchronization with the ignition signal from the ignition signal generator 1 when the rotation information signal exceeds a reference level; is a bypass circuit connected between the output end of the ignition pulse circuit 2 and the ground, which operates according to the ignition signal stop pulse from the rotation detector 8 and bypasses the ignition pulse from the ignition pulse circuit 2 to the ground. It is something to do.

In addition, FIG _. 2 is a waveform diagram showing the operating waveforms of each part in FIG _.
indicates the rotation information signal from the FV converter 7. Second
FIG. B shows the ignition stop pulse waveform output from the rotation detector 8.

Next, the operation will be explained. First, the ignition operation will be explained. The ignition signal generated from the ignition signal generator 1 in accordance with the rotation of the internal combustion engine is sent to the ignition pulse circuit 2.
is input. The ignition pulse circuit 2 shapes the waveform of this ignition signal and controls the closing angle to output an ignition pulse having a pulse width and an appropriate closing angle depending on the operating state of the engine. This ignition pulse is input to the switching circuit 3. This switching circuit 3 controls the energization of the ignition coil 4 in accordance with this ignition pulse. As a result, when the ignition coil 4 is cut off, a high voltage is generated on the secondary side of the ignition coil 4, and the engine is ignited and operated.

Next, the ignition stop operation will be explained. The pulse generator 6 generates a pulse signal having a fixed time width in response to the ignition signal generated by the ignition signal generator 1.
This pulse signal is input to the FV converter 7 and converted into a rotation information signal with a level proportional to the engine rotation speed. For example, this FV converter 7 charges and discharges a capacitor according to a pulse signal from a pulse generator 6, outputs a rotation information signal of a DC voltage at a level corresponding to the engine rotation speed at that time, and outputs a rotation information signal of a DC voltage corresponding to the engine rotation speed at that time. A rotation detector 8 compares the level of the signal with a reference voltage.

This comparison operation will be explained with reference to FIG. 2A. Here, the reference voltage _a1 is at a constant level, whereas the rotation information signal _a2 is a signal with a level proportional to the engine speed, and the level of the signal increases as the engine speed increases. Therefore, the rotation information signal a ₂ exceeds the reference voltage a ₁ at time t ₁ . At this time, the rotation detector 8 detects the second rotation in synchronization with the ignition signal.
Outputs the ignition stop pulse shown in Figure B. This ignition stop pulse is input to the bypass circuit 9, so
The bypass circuit 9 operates according to this ignition stop pulse, and the switching circuit 3 is connected from the ignition pulse circuit 2 to the switching circuit 3.
bypasses the ignition pulse about to be input to ground. Therefore, the input to the switching circuit 3 is eliminated, its switching operation is stopped, and the energization control of the ignition coil 4 is stopped. As a result, no ignition voltage is generated at the output of the ignition coil 4,
The engine will not ignite, resulting in a misfire, and the engine speed will drop. As a result, the rotation information signal _a2 decreases and eventually becomes smaller than the reference voltage _a1 , so
At this time _t2 , the rotation detector 8 no longer outputs the ignition stop pulse, the bypass circuit 9 stops bypass operation, and the ignition pulse from the ignition pulse circuit 2 is input to the switching circuit 3. . Therefore, the switching circuit 3 restarts the energization of the ignition coil 4, an ignition voltage is generated on the secondary side of the ignition coil 4, and the engine is ignited and operated.

Incidentally, when the engine speed increases again and the rotation information signal a ₂ becomes larger than the reference voltage a ₁ again, the above-described ignition stop operation is repeated as shown at time t ₃ in FIG. 2B. By repeating the ignition operation and the ignition stop operation in this manner, the engine rotation speed is limited to a predetermined rotation speed on average.

Here, the rotation detector 8 is the ignition signal generator 1
Since the ignition stop pulse is output in synchronization with the ignition signal from the ignition coil 4, the bypass circuit 9 is prevented from operating while the ignition coil 4 is energized, and the ignition occurs when the ignition angle is abnormally advanced. can be prevented, and there will be no adverse effects on the engine due to the ignition stop operation.

However, although this conventional device can achieve the desired overspeed prevention, its operation involves repeating a continuous ignition operation for a certain period of time and a misfire operation due to a reliable stoppage of the ignition operation, resulting in hunting in the operating characteristics. This causes large vibrations in the actual vehicle when it is activated. For this reason, for example, large vibrations at the start of the ignition stop operation not only cause a decline in maneuverability and feeling, but also cause abnormally sudden deceleration, which may cause the car to approach the following vehicle abnormally. Furthermore, since the ignition operation is completely stopped as an overspeed prevention operation, the guideline is It also had the disadvantage that it caused the driver to feel uneasy because it bounced around a lot.

The present invention was made in order to eliminate the drawbacks of the above-mentioned conventional devices, and it is an object of the present invention to provide an internal combustion engine ignition device that can reduce vibrations during operation.

An embodiment of the present invention will be described below in Figures 3 to 5.
This will be explained according to the diagram. In the figure, 60 is a pulse generator that responds to the ignition signal from the ignition signal generator 1 and outputs pulses for a fixed period of time from the ignition point, and 70 is used to charge and discharge a capacitor, for example, in synchronization with the pulses from the pulse generator 60. do
In an FV converter, for example, the time constant of the capacitor is set small so that the level of the charging/discharging waveform of the capacitor changes in a substantially triangular waveform according to the phase of the pulse. 80 is a comparator that compares the output of this FV converter with a constant level reference voltage and outputs an ignition stop pulse. Descriptions of other symbols are omitted as they are the same as those of the conventional device.

The operation will be explained below. Here, the ignition circuit system consisting of the ignition signal generator 1, the ignition pulse circuit 2, the switching circuit 3, and the ignition coil 4 is the same as that of the conventional device described above, so a description of its ignition operation will be omitted. To explain the ignition stop operation, the ignition signal generated by the ignition signal generator 1 as the engine rotates has a waveform shown in FIG. 4A.
The ignition pulse generated by the ignition pulse circuit 2 based on this ignition signal has a waveform shown in FIG. 4B. Time points _t4 and _t9 are each ignition time points, and the period from these time points _t4 to _t9 is the ignition cycle,
In the middle of this ignition cycle, there is a time point _t7 at which energization of the ignition coil 4 starts. In other words, the ignition coil ₄ is not energized during the period from ignition at time t 4 to time t ₇ , energization of the ignition coil 4 starts from time t ₇ , and the current flow is interrupted at time t ₉ to ignite. be done. The pulse generator 60 detects these ignition points, time t ₄
and time _t9 , respectively, and generate a pulse for a fixed time from that time. This pulse is a signal shown in FIG. 4C, and is a pulse extending from time _t4 to time _t6 a fixed time later. FV converter 70 charges and discharges the capacitor according to this pulse. Waveform shown in Figure 4D
g ₂ is the output of this FV converter 70, and during the period from time t ₄ to time t ₅ when pulses are input from the pulse generator 60, the output level increases due to the charging action of the capacitor, while the pulse During the period from time t ₆ to time t ₉ when no input is received, the output level becomes low due to the discharging action of the capacitor. In this way, the capacitor is repeatedly charged and discharged, and the output level of the FV converter 70 is determined by balancing at a level corresponding to the repetition period. In other words, this output waveform g ₂ has a ripple within the ignition cycle, and this ripple is at its lowest level at the ignition point (time t ₄ ) and reaches its highest level at time t ₆ after a certain period of time. , the average value is determined by the repetition period of charging and discharging described above, and since the width of the pulse from the pulse generator 60 is constant, the average value increases as the repetition period becomes shorter, that is, as the engine speed increases. It gets bigger. The comparator 80 compares the output of the FV converter 70 with an internally set reference voltage. This comparison operation is performed in FIG. 4D. Figure 4D
The waveform g ₁ shown in is the constant level reference voltage set inside the comparator 80, and the waveform g ₂ shown above is the reference voltage set inside the comparator 80.
An ignition stop pulse is output when the output of the FV converter 70 exceeds the reference voltage _g1 . FV converter 70
As described above, the average value of the output g ₂ increases as the engine speed increases. Therefore, in the process of increasing the engine speed, the level of the output g ₂ first exceeds the reference voltage g ₁ at the peak (time t ₆ ), and then as the engine speed increases, the average value of the output g ₂ increases. Therefore, the period during which the output g ₂ exceeds the reference voltage g ₁ is at time t ₆
It will move in the front and back direction more than 200 seconds, and will span the period from time _t5 to time _t8 .

As a result, the ignition stop pulse output from the comparator 80 becomes a pulse signal extending from time _t5 to time _t8 shown in FIG. 4E. The width of this pulse also increases before and after time _t6 according to the engine speed, as described above.

The bypass circuit _{9 is} activated in response to the ignition stop pulse shown in _{FIG .}
In order to bypass the ignition pulse of the output of the ignition pulse circuit 2 shown in FIG. 4B to ground during the partial period consisting of the period of
The waveform is shown in Figure F. In other words, the energization time of the ignition coil 4 is the period from time _t8 to time _t9 . Here, as the engine speed increases, the time point _t8 approaches the time point _t9 , so the energization time of the ignition coil 4 gradually becomes shorter, and eventually the ignition coil 4 is no longer energized at all.

That is, in proportion to the decrease in the energization time of the ignition coil 4, the output ignition voltage decreases and eventually becomes zero.

An example of the rotation speed characteristic of such a closing angle is shown in the fifth
This will be explained with a diagram. In this figure, the vertical axis is the closed circuit angle, and the horizontal axis is the engine speed.

Here, when the engine speed is N ₁ or less, the closing angle is constant at D ₁ , from N ₁ to N ₂ the closing angle is controlled from D ₁ to D ₂ , and when the engine speed is N ₂ or more, the closing angle is D 1. The closed circuit angle is constant at D ₂ .

The characteristics of the conventional ignition system are the extended characteristics of characteristic l.
As shown by l ₁ , the closed circuit angle is almost constant D ₂ even when the rotation speed exceeds N ₃ .

However, in this embodiment, due to the control operation as described above, the closing angle decreases from the predetermined rotation speed _N3 and becomes zero at the rotation speed _N4 . That is, the characteristic curve bends from characteristic l to characteristic _l2 at rotation speed _N3 .

In addition, the rotation speed N ₃ at which the reduction of the closing angle starts is:
Some high-output engines are relatively low-speed engines, and the engine speed is set at 5,000 revolutions per minute or more.

Now, as mentioned above, as the engine speed increases, the energization time of the ignition coil 4 is shortened, that is, the closing angle is controlled to be small, and the ignition voltage is decreased. The ignition voltage approaches the required ignition voltage necessary to cause the spark plug to spark, and eventually drops below the required voltage, causing the spark plug to misfire and the engine speed to drop. Then, as the engine speed decreases, the closing angle increases, and the ignition voltage output from the ignition coil 4 gradually increases until it becomes higher than the required voltage of the spark plug, and the engine is ignited.
Its rotational speed increases. When the rotational speed increases, the ignition voltage again becomes lower than the voltage required by the spark plug, and the engine is fired. By repeating the ignition and misfire caused by such changes in the ignition voltage, the engine is balanced at a predetermined rotational speed and overspeed is prevented.

In addition, even if the engine misfires, the ignition coil is still being driven, so the signal waveform at the ignition coil drive terminal is almost the same as under normal conditions, and based on this signal, the tachometer displays the engine speed. displays the correct rotational speed as usual.

As described above, according to the present invention, a closing angle reduction circuit is provided that reduces the closing angle of the ignition coil during the energization period of the ignition coil in accordance with an increase in the rotation of the internal combustion engine, thereby preventing overspeed. Not only does this happen, but the secondary voltage of the output of the ignition coil gradually decreases as the rotational speed becomes higher than that of the internal combustion engine, and fine ignition and misfire can be repeated repeatedly. , it is possible to significantly reduce vibration when the ignition is stopped, improve maneuverability and feeling, and prevent deceleration.In addition, in the case of a device that drives the tachometer by the signal from the ignition coil drive terminal, the This has the effect that the tachometer can operate stably in the same way as when igniting, and the pointer does not bounce, thereby eliminating the driver's sense of anxiety.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional device, and Figure 2 is a block diagram of a conventional device.
Fig. 3 is a block diagram showing an embodiment of the present invention, Fig. 4 is an operating waveform chart of each part of Fig. 3, and Fig. 5 is a characteristic diagram showing an example of the closing angle reduction characteristic. . In the figure, 1 is an ignition signal generator, 2 is an ignition pulse circuit, 3 is a switching circuit, 4 is an ignition coil, 5 is a power terminal, 60 is a pulse generator, and 70 is a
80 is a comparator, and 9 is a bypass circuit. In the drawings, the same reference numerals represent the same or equivalent parts.

Claims (1)

[Claims] 1. An ignition pulse generation circuit that generates an ignition pulse in synchronization with the rotation of an internal combustion engine, and a drive circuit that controls energization of an ignition coil in accordance with the ignition pulse from the ignition pulse generation circuit. The internal combustion engine ignition device is characterized by being provided with a closing angle reducing circuit that reduces the closing angle of the ignition coil during the energization cycle of the ignition coil from a predetermined rotational speed of the internal combustion engine as the rotational speed increases. internal combustion engine ignition system. 2 The closing angle reduction circuit includes a pulse generation circuit that generates a pulse of a predetermined time width in synchronization with the ignition timing, and a pulse signal from this pulse generation circuit in accordance with the phase of the pulse for each generation period of the pulse. a signal conversion circuit that converts the output signal into an output signal whose level changes; a comparison circuit that compares the output signal of the signal conversion circuit with a reference value; and a signal of the comparison circuit that closes the ignition coil during the energization period of the ignition coil. 2. The internal combustion engine ignition system according to claim 1, further comprising a closed circuit angle control circuit for controlling the angle. 3. The internal combustion engine ignition system according to claim 1 or 2, wherein the closing angle reducing circuit is configured to reduce the closing angle to zero.