JPH0130598Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to an engine control circuit, and more particularly to an engine control circuit that controls ignition and fuel injection to ensure simple self-propulsion when a control unit using a microcomputer fails.

[Prior art]

In recent years, with the rapid development of electronic technology, engine ignition and fuel injection control are also being controlled by microcomputers. For example, in an engine control unit using a microcomputer, the input signals are a crank angle pulse generated every unit angle rotation of the crankshaft and a reference position pulse indicating the reference rotational position of the crankshaft. Then, the microcomputer counts crank angle pulses with the origin at the point in time when the reference position pulse is generated, and when this counted value reaches a value calculated based on the rotation speed one revolution before, it controls the energization of the ignition coil. By doing so, the energization time and ignition timing are controlled. Furthermore, a control unit using a microcomputer attempts to improve fuel efficiency by controlling the amount of fuel injection based on information such as an accelerator signal, an intake negative pressure signal, and a water temperature signal.

[Problem that the idea aims to solve]

However, although the engine control circuit using the microcomputer described above can improve the efficiency of the engine by performing advanced control, it is possible that part of the control unit may malfunction or the microcomputer may fail. If the vehicle runs out of control for some reason, the engine cannot be controlled at all, making simple self-propulsion to a repair shop impossible. Therefore, an object of the present invention is to provide an engine control circuit that can be easily operated by itself to the extent of heading to a repair shop in the event of a failure of a control unit using a microcomputer.

[Means to solve the problem]

In order to achieve the above object, the engine control circuit according to the present invention provides a reference position pulse and a crankshaft control unit for an engine control unit configured with a microcomputer that generates an ignition control signal and a fuel control signal, and also generates a failure signal in the event of a failure. Select a reference signal generation circuit that generates a fixed ignition position signal using angle pulses and an ignition control signal that is normally generated from the engine control unit.
a selector that selects the ignition position signal generated from the reference signal generation circuit when the failure signal occurs and supplies it to the ignition device as an ignition control signal; a gate circuit that extracts the fuel control signal and supplies it to the fuel injection valve drive circuit;
a triangular wave generation circuit that is triggered by the ignition position signal to generate a triangular wave signal only when the failure signal occurs; and a triangular wave generating circuit that generates the triangular wave signal only during a period when the triangular wave signal is at a lower level than the intake negative pressure signal to inject the fuel. A comparator is added to the valve drive circuit to supply it as a fuel control signal.

[Effect]

In the engine control circuit configured in this way, if the control unit using a microcomputer fails, the additional circuit will operate to perform fixed ignition timing control and control the fuel according to the intake negative pressure. Since injection control is performed, simple self-propulsion to the extent of going to a repair shop is possible, and as a result, troubleshooting becomes easier.

【Example】

FIG. 1 is a circuit diagram showing an embodiment of an engine control circuit according to the present invention. In the figure, reference numeral 1 denotes an engine control unit using a microcomputer, in which a reference position pulse A indicating the reference position of the crankshaft is supplied from a sensor (not shown), and a crankshaft is generated every unit angle rotation of the crankshaft. Angle pulse B, water temperature signal C, accelerator signal D
and intake negative pressure signal E, etc. are used as input signals.
This engine control unit performs engine control under normal conditions by processing each of the above signals to generate an ignition control signal F and a fuel control signal G to bring the engine into optimal operating condition. ing. Moreover, this engine control unit 1 has a failure detection means inside it,
The microcomputer is configured to generate a failure signal H when a failure occurs due to runaway or the like. Reference numeral 2 denotes a reference signal generating circuit which generates a predetermined fixed ignition position signal I by inputting a reference position signal A and a crank angle signal B. 3 is an AND gate for determining whether the failure signal H generated from the engine control unit 1 matches the ignition position signal I; and 4 is an AND gate for determining the agreement between the failure signal H supplied via the inverter 5 and the ignition control signal F. gate, 6 is and gate 3,
This is an OR gate that receives the output of No. 4 as an input, and supplies the output as an ignition signal J to an ignition device (not shown). Therefore, these AND gates 3, 4, inverter 5 and OR gate 6 are connected to the fault signal H.
This constitutes a selector 7 that selects the ignition control signal F or the ignition position signal I and outputs it as the ignition signal J. 8 is inverter 9
fault signal H and fuel control signal G supplied via
10 is the fault signal H
and an AND gate to find a match between the ignition position signal I and the ignition position signal I;
11 is a triangular wave generation circuit, and an AND gate 1
A triangular wave signal K is generated every time an output is generated from 0. Reference numeral 12 denotes a comparator which generates an output signal L of "H" level only during a period when the level of the triangular wave signal K is lower than the level of the intake negative pressure signal E. Reference numeral 13 denotes an OR gate which receives the output signal of the AND gate 8 and the output signal L of the comparator 12, and supplies the output signal M as a fuel injection control signal M to a fuel injection valve drive circuit (not shown). FIG. 2 is a circuit diagram showing a specific example of the triangular wave generating circuit 11. In the same figure, 14 is AND gate 1
By being triggered by an output signal of 0,
This is a one-shot multivibrator circuit that generates a relatively narrow pulse determined by a resistor 15a and a capacitor 15b. 16 is a transistor 17, a Zener diode 18 and a resistor 19
A constant current circuit composed of ~21,
The output current charges the capacitor 22 in a constant current state. 23 is a discharging transistor connected in parallel to the capacitor 22, and inputs the output signal of the one-shot multivibrator circuit 14 via the capacitor 24 and resistor 25 to its base. The operation of the engine control circuit with the above configuration will be explained below. First, when the engine control unit 1 is operating normally, the failure signal H is always at the "L" level. Therefore, the selector 7 opens the AND gate 3 and prevents the output of the ignition position signal I generated from the reference signal generating circuit 2. On the other hand, the engine control unit 1 takes in and processes various sensor signals such as a reference position pulse A, a crank angle pulse B, a water temperature signal C, an accelerator signal D, and an intake negative pressure signal, thereby maintaining the engine in an optimal operating state. It generates an ignition control signal F and a fuel control signal G indicating the ignition point for the drive. The ignition control signal F generated in this way is
Since the output of the inverter 5 is at "H" level, it is taken out via the AND gate 4,
Further, the signal is supplied as an ignition signal J to an ignition device (not shown) via the OR gate 6, thereby controlling the ignition of the engine. Furthermore, since the output of the inverter 9 is "H", the fuel control signal G is supplied as the fuel injection control signal M to the fuel injection valve control circuit (not shown) via the route of the AND gate 8 and the OR gate 13. , the amount of fuel injected into the engine is controlled to an optimal value. On the other hand, as mentioned above, when the engine control unit 1 is operating normally, the failure signal H is always at the "L" level, so the output of the AND gate 10 is always at the "L" level. It's summery. Therefore, the triangular wave generating circuit 11 is not triggered by the AND gate 10. Here, when the triangular wave generation circuit 11 is not triggered by the AND gate 10,
It is configured to output the maximum level signal. Therefore, when the engine control unit 1 is operating normally, the output signal L of the comparator 12 is at the "L" level and does not affect other circuits. Next, if the engine control unit 1 breaks down for some reason, the engine control unit 1
The fault signal H generated from the fault signal H is inverted from "L" to "H" level. In this way, when the fault signal H goes to the "H" level, the outputs of the inverters 5 and 9 are set to the "L" level, so the AND gates 4 and 8 are closed, and the unstable ignition control signal is F and the fuel control signal G are prevented from being supplied to the ignition device and fuel injector drive circuit. On the other hand, the reference signal generation circuit 2 generates a reference position pulse A
By inputting the crank angle pulse B and the crank angle pulse B, a fixed ignition position signal I is constantly generated. This ignition position signal I is then a failure signal H.
Since is at “H” level, AND gate 3
The ignition signal J is further supplied to the ignition device via the OR gate 6 as an ignition signal J, thereby continuing ignition. In this case, since the ignition position signal I is a fixed signal, it is not necessarily the optimum ignition position, but it is possible to ensure simple self-driving. On the other hand, in the AND gate 10, the failure signal H is “H”
Since the state continues, the triangular wave generating circuit 11 generates an output every time the ignition position signal I is generated.
trigger. In this case, since the triangular wave generation circuit 11 is configured as shown in FIG. 2, for example,
Each time a trigger signal is supplied from AND gate 10, one-shot multivibrator circuit 14 is triggered to generate a relatively narrow pulse. The pulse output from the one-shot multivibrator circuit 14 turns on the transistor 23 via the capacitor 24 and resistor 25. When the transistor 23 is turned on, both ends of the capacitor 22 are shorted and all the charged charges are discharged. Next, when the transistor 23 is turned off, the capacitor 22 is charged with a constant current by the output of the constant current circuit 16, and the voltage across the capacitor 22 increases linearly. This operation is repeated every time the ignition position signal I is generated, and the triangular wave signals shown in FIG. 3a are sequentially output. Next, the triangular wave signal K generated from the triangular wave generating circuit 11 is compared with the intake negative pressure signal E in the comparator 12, and during a period when the level of the triangular wave signal K is lower than the level of the intake negative pressure signal E, As shown in FIG. 3(b), an output signal L of "H" level is generated. Therefore, this comparator 12
The output signal L generated from the intake air pressure signal E is a signal whose pulse width changes depending on the level of the intake negative pressure signal E, and is therefore suitable for fuel control. and,
The output signal L of the comparator 12 is taken out via the OR gate 13 and is supplied as a fuel injection control signal M to a fuel injection valve drive circuit (not shown) for fuel control. In this way, if the engine control unit fails, it will automatically switch to fixed ignition timing control and fuel control according to intake negative pressure.
At the very least, it will be possible to easily drive to a repair shop on your own.

[Effect of the idea]

As explained above, the engine control circuit according to the present invention operates when the engine control unit using a microcomputer fails and controls ignition and fuel injection according to various sensor signals. Even in the event of a breakdown, the vehicle can be driven as easily as a trip to a repair shop, and as a result, it becomes extremely easy to deal with the breakdown. Furthermore, since the circuit is extremely simple, the cost can be significantly reduced compared to the conventional case where a dual circuit system is used. Also, each time the ignition position signal is generated, a signal corresponding to the intake negative pressure signal is generated from the comparator, but the signal in this case is a triangular wave signal that is triggered and generated every time the ignition position signal is generated. Since it is generated by comparing the intake negative pressure signal with the intake negative pressure signal having a level corresponding to the intake negative pressure of the engine, it becomes a pulse width controlled signal and becomes a fuel control signal that drives the fuel injection valve drive circuit. This makes it possible to use the circuit directly as it is, thereby simplifying the circuit. Furthermore, since the fuel control signal output from the above-mentioned comparator is generated every time the crankshaft rotates, it corresponds to the engine rotation speed, and also has a relatively good relationship with the intake negative pressure. It has various excellent effects such as the ability to control the engine.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the engine control circuit according to the present invention, Fig. 2 is a circuit diagram showing a specific example of the triangular wave generating circuit shown in Fig. 1, and Fig. 3 a and b are the same as Fig. 1. FIG. 3 is an operation waveform diagram of the circuit shown in FIG. 1...Engine control unit, 2...Reference signal generation circuit, 3, 4, 8, 10...And gate,
5, 9... Inverter, 6, 13... OR gate, 11... Triangular wave generation circuit, 12... Comparator, 14... One-shot multivibrator circuit, 16... Constant current circuit, 22... Capacitor, 23... Transistor, 24... capacitor, 25... resistor.

Claims (1)

[Claims for Utility Model Registration] (1) At least a reference position pulse indicating the reference rotational position of the crankshaft in the engine, a crank angle pulse generated for each unit angular rotation of the crankshaft, and an intake negative pressure signal are taken in and processed. an engine control unit comprised of a microcomputer that generates an ignition control signal and a fuel control signal by controlling the engine, and generates a failure signal in the event of a failure; and a reference signal that generates a fixed ignition position signal using the reference position pulse and crank angle pulse. generating circuit and an ignition control signal normally generated from the engine control unit, and when the failure signal occurs, selecting the ignition position signal generated from the reference signal generation circuit to send the ignition control signal to the ignition device. a gate circuit that extracts the fuel control signal generated from the engine control unit and supplies it to the fuel injection valve drive circuit only when the failure signal is not generated; a triangular wave generating circuit that generates a triangular wave signal triggered by an ignition position signal; and a triangular wave generating circuit that generates a signal only during a period when the triangular wave signal is at a lower level than the intake negative pressure signal to the fuel injection valve driving circuit as a fuel control signal. An engine control circuit characterized in that it is provided with a comparator for supplying the engine. (2) The engine control circuit according to claim 1, wherein the triangular wave generating circuit generates a maximum level output signal when no fault signal is generated.