JPS63219854A - Fuel control device - Google Patents

Abstract

PURPOSE:To obtain a fuel control device which enables the ignition to gasoline to be prevented even if a burn-off control performs misoperation, by providing a means which stops one of the actions when the driving action of a fuel control valve and the action of a burn-off control part are simultaneously detected. CONSTITUTION:A ECU10, which determines a fuel injection quantity by every signal of a hot-wire intake amount sensor 2 (hereinafter called AFS), throttle sensor 4, etc., outputs an injector driving signal to a fuel injection valve 9. Simultaneously, the driving signal is reinput also to the ECU10. While the ECU10, which actuates a timer outputting a burn-off pulse by the program action, outputs a burn-off signal to the AFS2. While simultaneously, the burn-off signal is reinput also to the ECU10. If this signal is input, the ECU10 outputs no injector driving signal. While if the burn-off signal and the injector driving signal are simultaneously input, the injector driving signal prevents the driving signal of the burn-off signal or both from being output. Accordingly, ignition of fuel is prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a fuel control system that improves the high-temperature incineration (hereinafter referred to as Par 7 Off) operation of surface deposits of a hot-wire type intake air amount sensor used for fuel control of an internal combustion engine. It is related to the device.

[Conventional technology]

The properties of the hot wire intake air amount sensor change due to substances adhering to the hot wire surface, resulting in errors in the amount of fuel supplied to the engine, resulting in problems such as deterioration of exhaust gas and deterioration of driving performance.

In order to deal with such problems, it has been conventional practice to heat the hot wire to a temperature higher than the normal operating temperature when the engine is in a stopped state to remove the deposits on the surface of the hot wire. Regarding the method of removing parts, see JP-A-54-7
Since it is explained in Japanese Patent No. 6182, detailed explanation will be omitted.

It has been found through experiments that the heating temperature of the hot wire should be around 1000° C. in order to effectively perform the part-off operation.

However, heating the hot wire to 1000° C. can ignite the Ganlin air-fuel mixture, which is inconvenient for the intake air amount sensor disposed in the intake passage of the Ganlin engine. Therefore, in order to avoid ignition of the flammable air-fuel mixture, conventional methods have been used to ensure that the temperature and rotational speed during engine operation meet predetermined conditions when performing burn-off, and that gasoline that has been excessively supplied into the intake pipe during the warm-up process is sufficiently scavenged. Execution is allowed only if the Furthermore, after the engine stops, the time it takes for the air-fuel mixture to travel upstream from the fuel supply section to reach the intake air amount sensor is determined through experiments, and K
are doing. However, experiments have revealed that the above-mentioned conditions for executing the punt-off alone are insufficient, and that the punting-off may ignite the air-fuel mixture.

[Problem that the invention seeks to solve]

That is, in a state where the circuit for controlling the turn-off malfunctions and continuously performs the turn-off, the output of the intake air amount sensor is several tens of times the value that is originally output from engine startup to idling operation.

If the engine is started and fuel is supplied in such a malfunctioning state, several ten times the amount of fuel required by the engine will be supplied, which will not result in a complete explosion, and a large amount of gasoline will remain in the intake pipe. There is a risk that it will be ignited by a hot ray heated to about 1000 degrees Celsius.

The present invention was made to solve the above-mentioned problems, and it is an object of the present invention to provide a fuel control device that can prevent ignition of the fuel even if the burn-off malfunctions.

[Means for solving problems]

The fuel control device according to the present invention controls and detects the fuel injection valve based on the output of the hot-wire intake air amount sensor, detects the operation of the turn-off control section, and controls the drive of the fuel control valve and the operation of the turn-off control section. A means is provided for stopping at least one of the two when simultaneously detected.

[Effect]

In this invention, when the drive of the fuel control valve and the operation of the burn-off control section are detected at the same time, at least one of the two is stopped, and no fuel is ignited.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure shows the configuration of a fuel injection control device using a hot wire type intake air amount sensor (hereinafter referred to as AFS) that detects the intake air amount of an engine. In the figure, 1 is an air cleaner, and air that has passed through the air cleaner 1 is taken into a cylinder 8 via a surge tank 5 and an intake manifold 6. The intake air amount of this cylinder 8 is AFS
Detected by 2. Further, this intake air amount is controlled by the throttle valve 3. The throttle valve 3 is provided at the inlet of the surge tank 50. A throttle sensor 4 moves in conjunction with the throttle valve 3, extracts the opening degree of the throttle valve 3 as a voltage signal, and sends the output to an electronic control unit (hereinafter referred to as EC).
10 (referred to as U). 7 is an intake valve driven by a cam (not shown). Although only one cylinder 8 is shown in the figure for simplification, it is actually composed of a plurality of cylinders. A fuel control valve (hereinafter referred to as an injector) 9 is attached to each valley cylinder 8.

The ECUIO controls the fuel injection amount of the injector 9 so that the amount of air taken into each cylinder 8 becomes a predetermined air-fuel ratio A/B-. This ECUIO determines the fuel injection amount based on the signals of the AFS 2, crank angle sensor 11, start switch 12, engine coolant temperature sensor 13, and throttle sensor 4, and also determines the fuel injection amount of the injector 9 in synchronization with the signal of the crank angle sensor 11. Injection/7 of 9 Lus! Control the loop width. Also, the ECUIO outputs the pan-off control signal 14 to the AFS when all of the pan-off conditions are satisfied.
Occurs for 2. The configuration and operation related to the pan-off control of AFS2 are well known, so detailed explanations will be omitted.

FIG. 2 shows the internal configuration of the ECUIO, and 101 is an interface circuit for digital input of the crank angle sensor 111 and the start switch 12. The signal is sent to the output ticPU 105 of this digital interface circuit 101. The analog interface circuit 102 inputs the outputs of the AFS 2 and the water temperature sensor 13 and outputs the multi-breather (
MPX) 103. The output of the multi-blephr 103 is converted into a digital signal by an A/D (7f log/digital) converter 104 and output to the CPU 105. CPUI 05 is ROMI O5a, RAMI
It has a built-in O5b and timers 105c and 105d, and calculates the injector drive/zero width according to the program stored in the ROM 105a based on the input from the converter 104 between the interface circuit 101 and ~, and the timer 105C calculates the injector drive/zeros width for a predetermined time width. Outputs nozzles.

This t4 pulse is amplified by the drive circuit 106 to drive the injector 9, and the injector 9 injects fuel into the cylinder 8. The duration of the injection depends on the width of the pulse. Since the configuration and operation related to fuel control are conventionally known,
A detailed explanation will be omitted. The injector drive signal 15 from the drive circuit 106 is input again to the CPUI 05 via the digital interface circuit 101 on the one hand.

Next, the timer 105d is activated as a timer that outputs a burn-off pulse in response to a program operation, and this pulse is amplified by the drive circuit 107 and provided as the AFS2 Hebburn-O7 signal 14. In addition, the .--n-off signal 14 is sent back to the CP via the digital interface circuit 101.
It is input to U105. When the CPUI O5 receives this pan-off signal 14, it activates the drive circuit 106 of the injector 9.
If the parts-off signal 14 and the injector drive signal 15 are input at the same time, the drive pulse should not be output to the drive circuit 106, or the drive circuit should be turned off. Either do not output the drive pulse to the drive circuit 107, or
Both 06 and 107 drive/J? The program is configured in advance so as not to send any messages and to maintain this state.

In addition, since this grogram is extremely simple,
Explanation using drawings will be omitted.

Further, in the above embodiment, the signal indicating whether or not the AFS 2 is in the ground-off state is sent to the digital interface circuit 1.
01 to the CPU 105.

This is to protect the CPU 105 by interposing the interface circuit 101, since various induced noises are likely to be superimposed on the wiring from the drive circuit 107 to the AFS 2. Therefore, if there is no harmful induced noise, the output of the drive circuit 107 is directly transmitted to the CPU 1 within the ECUIO.
05 may be entered. This also applies to the injector drive signal 15.

Next, another embodiment of the ECUIO is shown in FIG.

In this embodiment, the drive circuits 106 and 107 send the injector drive signal 15 and the pan-off signal 14 to the drive inhibit circuit 108, and when the drive inhibit circuit 108 receives both signals 14 and 15, it outputs at least one of the drive circuits 106 and 107. Send a signal to prohibit the drive. Such a function can be realized with a simple circuit configuration having a gate function.

In this embodiment, the injector 9 can be accurately stopped even when the CPU 105 is in a runaway state and is in a turn-off state.

〔Effect of the invention〕

As described above, according to the present invention, when both the hot-wire intake air amount sensor's pan-off signal and the fuel control valve's drive signal are simultaneously detected, at least one of the fuel control valve's drive and the pan-off operation is stopped. Therefore, fuel is not supplied based on an erroneous output corresponding to burn-off, and therefore, ignition of fuel does not occur. Moreover, this effect can be obtained only by adding a few circuits or programs, and safety can be significantly improved at low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a fuel control device according to the present invention, and FIGS. 2 and 3 are a first and second embodiment of an electronic control unit according to the present invention, respectively! It is a lock diagram. 2...AFS, 8...Cylinder, 9...Fuel control valve, 10...ECU, 105...CPU, 106,
107... Drive circuit, 108... Driving prohibition circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A hot-wire intake air amount sensor installed in the intake passage of an internal combustion engine to detect the engine's intake air amount; a fuel control valve installed in the intake pipe of the internal combustion engine to inject fuel; and a a parts-off control unit that heats the hot wire to a temperature above the normal operating temperature to incinerate deposits on the surface of the hot wire;
It calculates the required fuel amount of the internal combustion engine based on the output of the hot-wire intake air amount sensor, controls and detects the fuel control valve based on the calculated value, and also detects the operation of the parts-off control section and drives and controls the fuel control valve. A fuel control device comprising means for stopping at least one of the parts-off control sections when the operations of the parts-off control sections are simultaneously detected.