JPS5853666A - Controller for electronic control carbureter - Google Patents

Abstract

PURPOSE:To enable an electromagnetic valve to be driven even in failure of a fuel cut controlling circuit by blocking drive signals in response to abnormality detecting signals of a means for generating the fuel cut electromagnetic valve driving signals to supply a predetermined voltage to an electromagnetic valve driving means. CONSTITUTION:A break contact of a switch 12 is connected to the output terminal of a fuel cut controlling circuit 8 connected to a circuit 11 for detecting abnormal operations to supply to a make contact a predetermined voltage Vr corresponding to a second driving signal for driving a drive circuit 10 and connect the output terminal to the circuit 10. When run signals generated by a circuit 8 are absent in a predetermined cycle, the switch 12 is driven by abnormality signals generated by the circuit 11 judging the absence to be a malfunction and signals of the circuit 8 are blocked to supply a predetermined voltage Vr to the circuit 10. Thus, fuel cut to an engine needing fuel supply can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an electronically controlled carburetor of a vehicle-mounted internal combustion engine.

In electronically controlled carburetor control devices, the air-fuel ratio is controlled by supplementarily adjusting the amount of air in the mixture based on information about exhaust gas components in order to minimize the harmful components in the exhaust gas emitted from the internal combustion engine. things are being done.

FIG. 1 shows a conventional example of such a control device.

In FIG. 1, each input terminal of an air-fuel ratio control circuit 1 includes a throttle sensor 2 that detects the fully closed state of a throttle valve (not shown), and a water temperature sensor 3 that measures the engine cooling water temperature.
, a crank angle sensor 4 that generates a signal corresponding to the rotation of the engine, and an oxygen concentration sensor 5 provided in an exhaust pipe (not shown) are connected to each other. A drive circuit 7 for driving an air amount adjusting solenoid valve 6 is connected to the output end of the air-fuel ratio control circuit 1 . Further, a fuel cut control circuit 8 is connected to each output terminal of the throttle valve/su 2, water temperature sensor 3, and crank angle sensor 4. Fuel canode control circuit 8
A drive circuit 1 for driving a fuel cut solenoid valve 9 is provided at the output end of the
0 is connected.

In the control device having such a configuration, the air-fuel ratio control circuit 1 detects the deviation of the output voltage of the oxygen concentration sensor 5 from the reference voltage, superimposes the proportional part and the integral of this deviation to generate a P-I signal, and generates the P-I signal. A first drive signal is generated based on the P-I signal. Then, in response to this first drive signal, the drive circuit 7 drives the air amount adjustment solenoid valve 6 to open and close an air bleed for air-fuel ratio correction provided in the carburetor. In addition, the air-fuel ratio control circuit 1 performs air-fuel ratio corrections that take into account operating conditions, such as low water temperature correction, acceleration correction, and deceleration correction, in accordance with the output signals of the throttle sensor 2, water temperature sensor 3, and crank angle sensor 4. ing. On the other hand, fuel cut control circuit 8
generates a second drive signal during normal running and during I-PAL, and in response to the second drive signal, the drive circuit 10 excites and drives the fuel cut solenoid valve 9 to supply fuel to the engine. However, when the engine requires fuel when driving at deceleration, etc., 1. When the fuel cut control circuit 8 is in a non-operating state, the fuel cut control circuit 8 stops generating the second drive signal. For example, if the cooling water temperature is 8
When the temperature is 0° C. or higher, the engine speed is 164° rpm or higher, and the throttle valve is fully closed, the generation of the second drive signal is stopped to stop the fuel supply to the engine. Then, when the engine speed decreases to 1l100rpm or less, the second drive signal is generated again to supply fuel to the engine even if the throttle valve is fully closed.

However, in such a control device, if the fuel cut control circuit 8 breaks down and the generation of the second drive signal stops, or the voltage of the second drive signal changes (if the voltage fluctuates more than usual, the fuel cuff), the electromagnetic valve 9 Since the engine is not driven, fuel is not supplied to the engine during normal driving, causing the engine to stall or become impossible to start.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for an electronically controlled carburetor that drives a fuel cut solenoid valve in the event of a malfunction due to a failure or the like in the fuel cut control circuit.

The control device according to the present invention includes an abnormality detection means that detects an operational abnormality in the fuel cut control circuit and generates an abnormal signal, and an input end of the drive circuit of the fuel cuff (fuel cuff) solenoid valve and an output end of the fuel cut control circuit. and a switch means for supplying a predetermined voltage to the input terminal of the drive circuit by disconnecting the connection in response to an abnormal signal and supplying a prescribed voltage to the input terminal of the drive circuit.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIG.

In FIG. 2, the same parts as in FIG. 1 are indicated by the same reference numerals, and the fuel cut control circuit 8 is connected to an abnormality detection circuit 11 that detects an abnormality in operation and generates an abnormality signal.

Further, a break contact of a switch 12 is connected to the output terminal of the fuel cut control circuit 8. A predetermined voltage Vr corresponding to the second drive signal is supplied to the make contact of the switch 12, and the selection output terminal of the switch 12 is connected to the input terminal of the drive circuit 10. In addition, the switch 12 is the abnormality detection circuit 1
1 is driven in accordance with the normal signal generated so that the selected output becomes a predetermined voltage Vτ from the second drive signal.

The rest of the configuration of the control device for an electronically controlled carburetor according to the present invention is the same as that shown in FIG. 1, and therefore will not be described here. Although the air-fuel ratio control circuit 1 and the fuel cut control circuit 8 are functionally completely different, they are formed by a single microcomputer.

In the control device according to the present invention, the fuel cut control circuit 8 includes a program for determining whether or not to generate the second drive signal according to each output signal of the throttle sensor 2, water temperature sensor 3, and crank angle sensor 4. The program is run by cycling through a predetermined range of steps. Also, the fuel cut control circuit 8
The microcomputer generates a run signal every time a predetermined step of the cyclic portion of the program is executed, and the run signal is supplied to the abnormality detection circuit 11. The abnormality detection circuit 11 determines that the fuel cut control circuit 8 is operating normally according to the zologram when the run signal is generated at a period within a predetermined range. However, when the run signal is not generated at a period within a predetermined range, the abnormality detection circuit 11 determines that the fuel cut control circuit 8 does not operate according to the zologram and is in a malfunctioning state, and generates an abnormality signal.

This abnormality signal drives the switch 12 to forcibly block the output signal of the fuel cut control circuit 8 and supply the predetermined voltage Vr to the drive circuit 10. Since the predetermined voltage Vr corresponds to the second drive signal, the drive circuit 10 drives the fuel cut solenoid valve to supply fuel to the engine.

As described above, according to the control device for an electronically controlled carburetor according to the present invention, when the fuel cut control circuit malfunctions, a disconnection voltage is supplied to the drive circuit of the fuel cut solenoid valve to forcibly drive the solenoid valve. Therefore, it is possible to prevent the fuel from being cut off when fuel should be supplied to the engine.

In the control device of the present invention, the abnormality detection circuit detects an abnormal operation of the fuel cut control circuit because it is not operating according to the program as in the above embodiment, but the voltage of the second drive signal An abnormality in operation may be detected based on the level.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional example of a control device for an electronically controlled carburetor, and FIG. 2 is a block diagram showing an embodiment of the control device of the present invention. Explanation of symbols of main parts 1...Air-fuel ratio control circuit 6...Air amount adjustment solenoid valve 8...Fuel cut control circuit 9...Fuel cut solenoid valve 11...Abnormality detection circuit 12...
Switch applicant: Japan Electronics Co., Ltd. Agent: Motohiko Fujimura, patent attorney

Claims (1)

[Scope of Claims] A control device for controlling an air amount adjustment solenoid valve of an electronically controlled carburetor of an internal combustion engine, the control device comprising: a fuel cut solenoid valve for supplying fuel to the engine according to a drive signal; an electromagnetic valve driving means; a driving signal generating means for generating the driving signal and stopping generation of the driving signal according to an operating state in which the engine does not require fuel; and detecting an abnormality in the driving signal generating means. an abnormality detecting means for generating an abnormal signal; and an apparatus provided between an input end of the fuel cut electromagnetic valve driving means and an output end of the drive signal generating means, and forcibly blocking the driving signal in response to the abnormal signal. and switch means for supplying a predetermined voltage to the input end of the fuel cut electromagnetic valve driving means.