JPS6113111B2 - - Google Patents

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to an ignition device for engine control.

[Background of the invention]

Conventionally, it has been known that a control device requiring reliability is provided with two systems of devices, and when a failure occurs in one system, the system is switched to the other system. (Electrical calculation, VOL.38, special issue,
(April 1970, Denki Shoin, Masao Tanaka, "Basic Sequence of Fail-Safe Circuits" pp. 118-119) However, what can be done to improve the reliability of engine control devices, especially ignition devices for engine control? However, when the other series is provided to improve reliability, it is not known how to operate this other series.

Next, an example of a conventional engine control ignition device will be shown. FIG. 1 is a block diagram of an ignition system for controlling a six-cylinder engine. The crank angle sensor 1 outputs two types of pulses depending on the rotation of the crankshaft. 1
One outputs one pulse for each degree of crankshaft rotation, and the other outputs one 120 degree pulse for every 120 degrees of crankshaft rotation. This 120 degree pulse is generated at the maximum advance angle value θm degrees for each cylinder. The electronic circuit 10 calculates a value θs obtained by subtracting the optimum advance angle value θr degrees determined from the engine operating conditions from θm degrees.
Each pulse is counted once and a signal representing the ignition timing is output. This provides optimal ignition timing.

Water temperature sensor 2 detects the water temperature of the engine, and sets an advance angle correction amount, that is, a control amount, in counter 3 in accordance with this. Counter 3 is the crank angle sensor output.
Counting is started with a 120 degree pulse, and after counting the pulse once by the above control amount, a count end signal is output to the next stage counter 5.

A counter 4 that detects the engine rotational speed counts the above-mentioned one-time pulse for a certain period of time, and sets a control amount in the counter 5 according to the rotational speed. The counter 5 is activated by a count end signal from the counter 3 at the previous stage, and outputs a count end signal to the next stage counter 8 after counting the pulses once by a set value.

The slot sensor 6 outputs a digital output to the comparator circuit 7 in accordance with the throttle opening degree. The comparator circuit 7 counts the one-degree pulse for a certain period of time and compares the value with the value of the throttle opening, thereby setting the advance angle control amount in the counter 8 in accordance with the throttle opening.

The counter 8 starts counting in response to the count end signal from the counter 5, and outputs a count end signal when it has finished counting the number of one-time pulses corresponding to the set value. In response to this, the counter 9 is started, and an ignition signal is outputted to make the subsequent transistor conductive and cause the primary coil current to flow through the ignition coil. This signal continues until the count 9 counts a certain number of times, and ends when the count ends. With this termination, the transistors at the subsequent stage are cut off. In other words, the output of the above ignition signal is stopped,
At this point, the primary coil current of the ignition coil is interrupted and a high voltage is created in the secondary coil of the ignition coil. This voltage is distributed to each spark plug of each cylinder (not shown) via a distributor 11. The above operation is performed by the above crank angle sensor 1.
is repeated for each occurrence of a 120 degree pulse of output.

An example of a specific circuit constituting each of the above counters is shown in FIG. Each counter is composed of a combination of a CMOS up-down counter 12, RCA's CD4029, and several other gates.
CD4029 is used as a down counter in this example.

Initially, flip-flop 14 is in a reset state. Therefore, the input terminal CI of the counter 12 becomes high level, and the counting operation of the counter 12 is prohibited. Next, when a start signal, that is, an activation signal is input, the terminal PE, which is the preset enable input terminal, becomes high level, and the set value of the preset input is set in the counter 12.
At the same time, the flip-flop 14 is set and the input terminal IC becomes low level. Therefore, the prohibition of counting operation is lifted, and the counter 12 starts counting down. When the count value reaches zero, a pulse as a signal is output from the terminal CO, and this signal is applied to the next stage counter via the inverter 15, so that the next stage counter starts counting operation.

A NOR condition is established between the output from the terminal CO and the one-degree pulse output from the crank angle sensor 1 by the gate 13, and the flip-flop 14 is reset under this condition. Therefore, after half a pulse of the one-time pulse, the flip-flop is reset, and the output of this flip-flop inhibits the counter 14 from counting again.

As mentioned above, conventional ignition devices have low reliability because they do not take measures against internal failures.

[Purpose of the invention]

An object of the present invention is to provide a highly reliable ignition system for engine control.

[Summary of the invention]

The feature of the present invention is to detect a pulse that occurs when the main electronic circuit is operating normally, and to detect a failure that has occurred in the main electronic circuit by detecting that the generation of this pulse has stopped for a predetermined period of time or longer. However, the backup circuit was made to operate. This has the effect of improving reliability.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described using FIG. 3. Crank angle sensor 1 and main electronic circuit 10
has the same structure as the conventional apparatus shown in FIGS. 1 and 2. Therefore, an ignition signal is output based on the 120 degree pulse output of the crank angle sensor 1. The fixed advance angle circuit 16 has basically the same configuration as the circuit shown in FIG. 2, and a fixed value is set in a counter as a controlled variable. One-shot multivibrator 17
is a circuit for generating an ignition signal with a constant time width, which is triggered by a count end signal of a counter constituting the fixed advance angle circuit 16, and outputs an ignition signal with a constant time width. During the connection time of this ignition signal, the transistor shown in FIG. 1 is conductive, and electromagnetic energy is stored in the ignition coil. At the end of the ignition signal, the transistor becomes non-conductive and a high voltage is generated in the ignition coil. The circuits 16 and 17 act as backup circuits. The on-off gate 18 outputs an ignition signal in response to the outputs of both the electronic circuit 10 and the backup circuit.

One-shot circuit 19 and inverter 20 constitute a failure detection circuit, and output a signal indicating a failure to AND gate 21. AND gate 21 operates the backup circuit in response to this signal. The one shot circuit 19 is set so that the duration of its output pulse is always longer than the time width from one ignition signal to the next ignition signal, and
Use a circuit configuration that allows retriggering. In other words, when the one-shot circuit 19 is in an unstable state and outputting a pulse, when the next trigger signal is input, the trigger is applied again from that point on, and a circuit that maintains the output pulse is used. By using such a circuit, each time the circuit 19 is triggered by the output signal of the electronic circuit 10, the passage of time is measured starting from the trigger, and the next signal is output from the main electronic circuit 10 within the set time. It is detected whether it is output or not.

When the main electronic circuit 10 is operating normally,
Ignition signals are output one after another from the main electronic circuit 10,
The circuits 19 are triggered one after another, and the output of the circuit 19 is always kept at a high level. As a result, the output of the inverter 20 is always at a low level, and no signal indicating a failure is output. Therefore, AND gate 21 remains closed and circuits 16 and 17 do not operate.

Now, if any failure occurs in the electronic circuit 10, the generation of the ignition signal will stop and the triggering to the circuit 19 will also stop. When the trigger is stopped for more than the set time of the circuit 19, the circuit 19 enters a stable state and its output becomes a low level. As a result, inverter 2
The output of 0 becomes high level and a signal indicating a failure is generated. By inputting this signal to the AND gates, the AND gates open, and the outputs of the crank angle sensors 1 are input to the circuits 16 through the AND gates 21, and the circuits 16 operate based on the outputs of the crank angle sensors 1. Operate. The circuit 16 generates an ignition signal based on a preset ignition control amount. Although this ignition control amount is not necessarily the optimum value, this signal maintains ignition and the engine continues to operate.

〔Effect of the invention〕

According to the present invention, a failure in the main electronic circuit can be detected with a simple circuit, and the backup circuit is operated based on the detection result, so that a highly reliable ignition system can be obtained.

Further, in the above embodiment, a one-shot multivibrator is used to detect a failure, so the above embodiment has the advantage that a failure can be easily and accurately detected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional ignition system for engine control, FIG. 2 is a detailed circuit diagram of the counter shown in FIG. 1, and FIG. 3 is a block diagram showing one embodiment of the present invention. 1...Crank angle sensor, 10...Main electronic circuit, 16...Fixed advance angle circuit, 17 and 19...One-shot multivibrator, 18...OVER gate, 20...Inverter, 21...AND gate.

Claims (1)

[Claims] 1. A reference angular pulse generating means that corresponds to the rotation of the engine crankshaft and generates a reference angular pulse at a predetermined rotational angle position of each piston; A main electronic circuit that generates an ignition signal when the crankshaft rotates by the above-mentioned control amount with reference to the An ignition device for controlling an engine, comprising a failure detection circuit that activates the backup circuit when the ignition device stops for a predetermined period of time or more.