JPS62248838A - Fuel control device - Google Patents

Abstract

PURPOSE:To eliminate the inconvenience of igniting a remaining gasoline which is vaporized and flows back by executing the burn off of the heating coil of an intake air quantity sensor within a defined time after intake is nearly stopped, after an engine is stopped. CONSTITUTION:An electronic control unit 10 generates a burn off control signal 14 when every burn off condition is satisfied, and sends out the signal to a heating coil type intake air quantity sensor 2. When an intake air quantity detected by the intake air quantity sensor 2 after an engine is stopped becomes lower than a defined value, it is considered intake is nearly stopped and a timer is set and, when judged the time is over, burn off is executed. Said time is set shorter than the time at which the remaining gasoline in a fuel feeding part is vaporized and flows back after the intake is stopped. Thereby, it is eliminated that the gasoline which has flowed back near the intake air quantity sensor 2 is ignited by burn off.

Description

Detailed Description of the Invention [Industrial Field of Application] This invention is applicable to gasoline mixing when performing high-temperature incineration (hereinafter referred to as burn-off) of the surface of a hot-wire type intake air amount sensor used for fuel control of an internal combustion engine. The present invention relates to a fuel control device that eliminates the risk of accidental ignition.

[Conventional technology]

The characteristics of hot wire intake air flow sensors change due to substances that adhere 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 reduction in driving performance.

In order to deal with this problem, 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 burn off deposits on the surface of the hot wire. / Regarding the method of turning off
Since it is explained in Publication No. 76182, a 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 burn-off operation. .

If you heat the gasoline mixture to 1000℃ while stirring, it is possible to ignite the gasoline mixture! 1. For the intake air amount sensor installed in the intake passage of a gasoline engine? It's unfortunate.

Therefore, in order to avoid ignition of the gasoline mixture, conventional methods have been used to ensure that the temperature per revolution during engine operation satisfies a predetermined condition when performing burn-off, and that the excess gasoline supplied into the intake pipe during the warm-up process is sufficiently scavenged. Execution is allowed only if the

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

[Problem that the invention seeks to solve]

In other words, even if one 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.
), the gasoline mixture rapidly flows up to the vicinity of the intake air amount sensor after the engine is stopped, and if a turn-off is performed in this state, the gasoline may ignite.

The present invention was made to solve this problem, and an object of the present invention is to provide a fuel supply 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, when stopping the engine,
A means is provided for controlling the engine to turn off within a predetermined time period from the time when it is determined from the output of the intake air amount sensor that the intake air of the engine has stopped.

[Effect]

In this invention, after the intake air stops, the gasoline accumulated in the fuel supply section is vaporized and the burn-off is executed before it reaches the vicinity of the intake air amount sensor to prevent the gasoline from igniting.

〔Example〕

Embodiments of the fuel control device of the present invention will be described below with reference to the drawings. FIG. 11 is a block diagram showing the configuration of one embodiment of the present invention, and is a diagram showing the configuration of a fuel control device using a hot wire intake air amount sensor (hereinafter referred to as AFS) for detecting the intake air amount of the engine.

In Fig. 1, 1 is the air cleaner and 2 is the AFS.

3 is a throttle valve that controls the intake air amount of the engine.

The throttle sensor 4 moves in conjunction with the throttle valve 3, extracts the opening degree as a voltage signal, and sends it to an electronic control unit 10 (hereinafter referred to as ECU).

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

In the figure, only one cylinder portion of the engine is shown for the sake of simplicity, but the cylinder 8 (cylinder) is actually composed of multiple cylinders.

Fuel control valve (hereinafter referred to as injector) for each cylinder 8
9 is attached. A button is provided to control the fuel injection amount of the injector 9 to a predetermined air-fuel (A/F) ratio with respect to the amount of air taken into each cylinder 8 using the KECUIO.

The ECUIO determines the fuel injection amount based on the signals from the AFS 2, the crank angle sensor 11, the start switch 12, the engine coolant temperature sensor 13, and the throttle sensor 4, and injects the fuel from the injector 9 in synchronization with the signal from the crank angle sensor 11. The parable of Δrus is a trap that controls the width of the lus.

The ECUI O generates a pan-off control signal 14 and sends it to the AFS 2 when all of the pan-off conditions □ are satisfied. The configuration and operation related to the pan-off control of AFS2 are similar to those known in the art, and therefore detailed explanations will be omitted.

The second figure is a block diagram showing the internal structure of EeUlo, and in this figure 101 is the crack angle sensor 1.
1. An interface circuit for the digital input of the start switch 12, 102dAFS2, an interface circuit for the analog input of the cooling water temperature sensor 13, 103 is a multiplexer, A;/D (analog/digital) converter 1
04, analog inputs from the AFS 2 and the cooling water temperature sensor 13 are sequentially converted into digital values.

105 is a cpty in which a ROM 105a, a RAM 105b, and timers 105e and 105d are installed, which are stored in the ROM 105a based on the signals input from the interface circuit 101 and the A/D converter 104! The injector drive pulse width is calculated according to the log2m, and the timer 105c outputs a pulse with a predetermined time width.

The /4 pulse output from the timer 105c is sent to the drive circuit 10.
6 and drives the injector 9. Since the above configuration related to fuel control is conventionally known, a detailed explanation will be omitted.

Next, the timer 105d is a timer that outputs the turn-off signal by the program operation shown in FIG. The program related to the burn-off will be explained in detail below with reference to FIG.

This FIG. 3 shows only the control from engine stop to turn-off, and does not show fuel control in the operating state.

In step S1, the output Qa of AFS2 is read, and in step S2, it is compared with the intake air amount Qth.

As shown in FIG. 4, the intake air amount Qth is set to a value at which it can be considered that the intake air has almost stopped.

Qa (When Qth is established, move to step S3,
A timer is set. In Fig. 4, the time limit of the timer is longer than the time T required for the output Qa to fall below the intake air amount Qth and become almost completely O, and the residual gasoline in the fuel supply section evaporates and flows upstream after the intake lid stops. Set it to a time shorter than the time it takes to arrive.

When it is determined in step S4 that tie A is over.

Proceeding to step S5, a look-off is executed.

In addition, if the intake air amount decreases quickly after the engine stops, Qa
(Prunoff may be executed immediately after Qth is established. In that case, it goes without saying that step S4 can be omitted.

〔Effect of the invention〕

As explained above, in this invention, after one engine stops and the intake air amount almost stops, until the residual gasoline vaporizes and goes upstream from the fuel supply section, the burn-off is executed, so that the gunlin is ignited. There is no inconvenience, and
It has the excellent feature that the above effect can be achieved by adding a small amount of f rodaram.

[Brief explanation of drawings]

Fig. 1 is a FA 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 structure of the ECU in the fuel control device of Fig. M1, and Fig. 3 is a fuel diagram of the present invention. A flowchart showing an embodiment of flow graph A of the control device, and FIG. 4 is an output waveform diagram of the AFS when the engine is stopped. 2-AFS, 3--Throttle valve, 4--Throttle sensor, 8--Cylinder, 9--Injector,
10...ECU, 11...R2 ink angle sensor, 1
2- Start switch, 13... Cooling water temperature sensor, 10
5...CPU. 105a-" ROM, 105b...RAM, 105e
=・105 d−・・・Timer, 106 , 107 ・・
・Drive circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] means for supplying fuel to the internal combustion engine in accordance with the operation of the fuel control valve; a hot-wire intake air amount sensor disposed in the intake passage of the internal combustion engine to detect the amount of intake air; Control means for heating the hot wire to a temperature higher than the normal operating temperature to incinerate deposits on the surface of the hot wire at the time when it is determined from the output that the intake air of the internal combustion engine has stopped, or within a predetermined time period from that time. Fuel control device.