JPS62248850A - Fuel controller - Google Patents

Abstract

PURPOSE:To dissolve the trouble of ignition of the staying gasoline which rises after vaporization by executing the burn-off of the heating wire of an intake quantity sensor when the opening degree of a throttle valve is below a prescribed value on engine stop. CONSTITUTION:An electronic control unit 10 generates a burn-OFF control signal 14 and sends it into a heating wire type intake quantity sensor 2 when all the burn-off conditions are established. When the output of a throttle sensor 4 lowers below a prescribed value after the engine stop, burn-off is executed. Said prescribed value is set to a value with which a throttle valve 3 is consid ered to be nearly closed. Therefore, when the throttle valve 3 is effectively in the closed state, the necessary time for the vaporization of the gasoline staying in a fuel feeding part and rising to the vicinity of the intake quantity sensor 2 is exceedingly long, ignition of gasoline can be prevented even if burn- off is executed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to high-temperature incineration (hereinafter referred to as "one-off") of surface deposits of a hot-wire type intake air amount sensor used for fuel control of an internal combustion engine. , relates to a fuel control device that eliminates the risk of igniting a gasoline mixture.

[Conventional technology]

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

To address these issues, 4 heat* temperatures above normal operating temperatures are used when the engine is at a standstill.

It has been conventional practice to heat the wire to a temperature of 100°C to remove deposits on the surface of the hot wire. Regarding the “non-off” method,
Since this is explained in Japanese Patent Application Laid-Open No. 54-76182, detailed explanation will be omitted.

Experiments have shown that the heating temperature of the hot wire should be around 1000 DEG C. in order to effectively perform the pan-off operation.

If you heat the hot wire to 1000'C while stirring, it will be possible to ignite the gun/sun mixture.
This is inconvenient for the intake air amount sensor disposed in the intake passage.゛Therefore, in order to avoid ignition of the gasoline mixture as in the past, when executing Resene O7, the temperature during engine operation and the number of revolutions must meet the predetermined conditions, and the gasoline that was excessively supplied during the warm-up process into the intake pipe must be sufficient. Execution is allowed only when the air is scavenged.

However, it has been found through experiments that merely determining the above-mentioned conditions for executing the continuous off is insufficient, and that the gasoline mixture may be ignited due to the continuous off.

[Problem that the invention seeks to solve]

In other words, even if the engine has been warmed up, a large amount of gasoline may remain near the fuel control valve due to intake air blowback when the engine is operated at full throttle, and the amount of intake air may rapidly decrease after the engine is stopped. There is an inconvenience that the gasoline mixture flows up to the vicinity of the sensor, and if a non-off operation is performed in this state, the gasoline will be ignited.

The present invention was made to solve this problem, and an object of the present invention is to provide a fuel control device that does not have the risk of igniting a gasoline mixture.

[Means for solving problems]

The fuel control device according to the present invention is provided with means for controlling the throttle valve to turn off continuously when the opening degree is below a predetermined degree when the engine is stopped.

[For production]

In this invention, when the throttle valve is effectively closed, the gasoline accumulated in the fuel supply section vaporizes and flows up to the vicinity of the intake air amount sensor extremely slowly. prevent ignition.

〔Example〕

Embodiments of the fuel control device of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the invention, and is a diagram showing the configuration of a fuel control device using a hot wire intake air flow sensor (hereinafter referred to as AFS) that detects the intake air amount of the engine. .

In this Figure 1, 1 is an air cleaner, 2 is an AFS,
3 is a throttle valve that controls the intake air t of the engine; 4
moves in conjunction with this throttle valve, extracts its opening as a voltage signal, and sends it to the electronic control unit 10 (hereinafter referred to as E).
CU).

Nine, an intake manifold 6 is connected to the surge tank 5, and the intake manifold 6 is connected to the cylinder 8.
is connected to. The cylinder 8 is provided with an intake valve 7 driven by a cam (not shown).

□ ゛ In the figure, only one cylinder part of the engine is shown for the sake of simplicity, but in reality it is composed of multiple cylinders.

Fuel control valves for each cylinder (hereinafter referred to as injectors)
9 is marked as a loss. The fuel injection amount of this injector 9 is controlled by the ECUIO so that it becomes a predetermined air fuel (A/F) ratio with respect to the amount of air taken into each cylinder/8.

ECU10IIiAFS2 and crank angle sensor 11
, starting switch 12, engine cooling water temperature sensor 13,
The fuel injection amount is determined based on the signal from the throttle sensor 4, and the nozzle IIm of the fuel injection pulse from the injector 9 is controlled in synchronization with the signal from the crank angle sensor 11.

The ECUIO is designed to generate a non-off control signal 14 and send it to the AFS 2 when all non-off conditions are met. The configuration and operation related to the nine-off control of the AFS2 are similar to those known in the art, so detailed explanations will be omitted.

FIG. 2 is a block diagram showing the internal configuration of the tiEcU 10. In FIG. 2, 101 is a crank angle sensor 1.
11 is an interface circuit for the digital input of the start switch 12, 102tiAFS2, and an interface circuit for the analog input of the cooling water temperature sensor 13.

103 is a multiplexer, and an A/D (analog/digital) converter 104 converts AFS2. Analog input from the cooling water temperature sensor 13 is sequentially converted into digital values.

'CPUI O5tiROM105a, RAM10
5b and timers 105e and 105dt', the injector drive pulse width is calculated according to the program stored in the ROM 105a based on the signals input from the interface circuit 101 and the A/D converter 104, and the timer 105C outputs a noggle with a predetermined time width.

This pulse is amplified by a drive circuit 106, and the drive circuit 106 drives the injector 9.

The above-mentioned configuration related to fuel control is conventionally known, so a detailed explanation will be omitted.

Next, the timer 105d is a timer that outputs a non-off pulse by the four-gram operation shown in FIG.

Hereinafter, the programs related to Non-O7 will be explained in detail with reference to FIG. This diagram shows 79-
Only the control leading to engine 7 is shown, and the fuel control in the operating state is omitted.

In step S1 of FIG. 3, the throttle sensor output vQ is read, and in step S2, it is compared with the intake air amount Vth. This intake air amount vth is set to a value that allows it to be considered that the throttle valve 3 is almost closed. VQ<vth
When this is true, transfer parn-off is executed in step 83.

In FIG. 3, if VQ<vth does not hold, the process ends without executing the non-off.

In the embodiment shown in FIG. 3, the state of the throttle valve 3 is determined by the throttle sensor 4, but the same operation can be obtained by using a switch signal activated at the throttle closed position.

〔Effect of the invention〕

As explained above, this invention executes the non-off operation when the throttle valve is closed to prevent the residual gasoline from vaporizing and going upstream from the fuel supply section after the engine is stopped. This is not a problem; it has the excellent feature that the above effects can be achieved with a few additions to the program.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the fuel control device of the present invention, FIG. 2 is a block diagram showing the internal configuration of the ECU in the fuel control device of FIG. 1, and FIG. 3 is the same fuel control device as above. 3 is a flowchart showing an example of a program. 2... AFS, 3... Throttle valve, 4... Throttle sensor, 8... Cylinder, 9... Injector, 10... ECU, 11... Crank angle sensor,
12...Start. Switch, 13...Cooling water temperature sensor, 1o5...C
P.U. 105a...ROM, 105b...RAM, 105
e. 105d...Timer, 106.107...Drive circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. □

Claims (1)

[Claims] A hot-wire type intake air amount sensor is installed in the intake passage of an internal combustion engine whose intake amount is adjusted by a throttle valve.The engine's required fuel amount is calculated based on the output of this hot-wire type intake air amount sensor, and based on the calculated value. By controlling the fuel control valve, the desired fuel is supplied, and when the throttle valve is below a predetermined opening when the engine is stopped, the hot wire is heated to a temperature higher than the normal operating temperature to incinerate the surface deposits of the hot wire. A fuel control device comprising a means for controlling the fuel.