JPS62233437A - Fuel supply device for engine - Google Patents

Abstract

PURPOSE:To prevent an excessive or deficient fuel supply caused by sensing errors of an air flow meter and an engine stall, by providing a lower limit setting means for controlling a fuel supply quantity at deceleration to an amount greater than a fuel supply quantity at an idling. CONSTITUTION:An engine 1 has an intake air passage 2 provided with vane type air flow meter 4, a fuel injector 7 or the like. In this case, a quantity of fuel to be supplied from the fuel injector 7 is controlled by an electronic control unit 9 as a lower limit setting means to which respective signals from a rpm sensor 8, the air flow meter 4 and an idle switch 6 are applied. A quantity of fuel supplied in deceleration is controlled to an amount greater than a quantity of fuel supplied in idling operation corresponding to an opening of a throttle valve 5 regardless of a value sensed by the air flow meter 4. With this arrangement, an excessive or deficient fuel supply and an engine stall is prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an engine fuel supply device that is capable of preventing engine stalls due to false detection or detection deviation due to inertia of an air flow meter during deceleration. .

[Prior art]

As an engine fuel supply device that controls the fuel supply amount with respect to the intake air amount of the engine, for example,
As shown in Japanese Patent No. 13, there is a system that detects the amount of intake air with a vane type air flow meter and controls the amount of fuel supplied to the engine in accordance with the detected value.

In such a conventional engine fuel supply system,
During deceleration, the air flow meter moves due to the inertia of the vane,
Less fuel was supplied than the required amount of fuel relative to the amount of intake air, sometimes resulting in engine stall. Furthermore, during deceleration, the values detected by the air flow meter varied, which could lead to insufficient fuel supply and an engine stall.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and is capable of preventing false detection due to inertia of the air flow meter during deceleration and engine stall due to detection deviation.
The purpose is to provide a fuel supply device for an engine.

[Structure of the invention]

In order to achieve the above object, the engine fuel supply device according to the present invention is an engine fuel supply device in which the amount of fuel supplied is controlled according to the output of a vane-type air flow meter that detects the amount of intake air. A lower limit setting means is provided to control the fuel supply amount during deceleration to be higher than the fuel supply amount during idling operation, and the fuel supply amount is stabilized at a level that does not cause engine stall regardless of movement due to inertia of the air flow meter or detected deviation during deceleration. It is characterized by a good supply.

[Example] An example of the present invention will be described below based on FIGS. 1 to 4.

The intake passage 2 of the engine I includes an air cleaner 3, a Höhn type air flow meter 4, a throttle valve 5, and an idle switch 6 that is turned on when the throttle valve 5 is at the idle position, which is the position during idle operation. ,
A fuel injector 7 is provided. The amount of fuel supplied to the fuel injector is controlled by a rotational speed sensor 8 that detects the engine rotational speed N0, an air flow meter 4, and an electronic control unit 9 serving as a lower limit setting means that inputs each output of the idle switch 6. This electronic control unit 9
are the basic fuel injection amount corresponding to the outputs of the air flow meter 4 and the rotation speed sensor 8, and the basic pulse width T corresponding to the period during which fuel is injected from the fuel injector 7 to supply the basic fuel injection amount of fuel. , and a pulse width calculation unit 10 that calculates the basic pulse width T based on the calculation result.
It has a pulse signal output section 11 that outputs a pulse signal having P to the fuel injector 7. Moreover, this electronic control unit 9 has a basic pulse width T P during idling operation.
A learning storage unit 12 that learns and stores IOL, a deceleration determining unit 13 that determines whether the operating state of the engine 1 is decelerating operation, and a learning storage unit that determines whether the operating state of the engine 1 is decelerating operation. The basic pulse width T stored in 12
, , Ilt, and corrects the calculation result of the pulse width calculation section 10 to the basic pulse width TPIDL. The deceleration determination unit 13 determines whether the engine rotation speed detected via the rotation speed sensor 8 exceeds a predetermined idle rotation speed (101000 rpm in this case) and the idle switch 6 is on.
is configured to determine that the vehicle is decelerating. Further, when the water temperature of the engine 1 is above a predetermined value and the idle switch 6 is on, the learning storage section 12 stores
Read the basic pulse width T at that time, repeat this reading a predetermined number of times (in this case, n-20 times), calculate the total average value, and store this calculation result as the basic pulse width at idle T P I OL It is configured as follows.

In the above configuration, when engine l is operated at deceleration,
First, it is determined whether or not the idle basic pulse width TPIDL is stored in the learning storage unit 12 (Sl), and if it is not stored, the idle basic pulse width T P
IDL learning and memorization is executed (S2). When it is confirmed that the idle basic pulse width TP1DL is stored in the learning storage unit 12, the deceleration determination unit 13 determines that the engine rotation speed has reached a predetermined idle rotation speed (here, 1
It is monitored whether the engine speed exceeds 01000 rpm (S3), and when the engine speed exceeds a predetermined idle speed, it is further monitored whether the idle switch 6 is on (S4). When the engine speed exceeds the predetermined idle speed and the idle switch 6 is on, it is determined that the engine l is decelerating, and the pulse width correction means 14
is the basic pulse width T stored in the learning storage section 12.
P I OL is read out and the calculation result of the pulse width calculation section 10 is corrected to its basic pulse width TFIOL (S
5). The pulse signal output section 11 uses this basic pulse width T□,
A pulse signal having the following value is output to the fuel injector, and during the on-time of this pulse signal, fuel is injected from the fuel injector 7 into the intake passage 2. Therefore, the amount of fuel supplied during deceleration operation corresponds to the amount of intake air passing through the intake passage 2 that is throttled by the throttle valve 5 at the opening degree during idling operation, regardless of the amount of intake air detected by the airflow make 4. I am made to do so. As a result, engine stall can be reliably prevented. When the deceleration operation ends and the engine speed drops below the predetermined idle speed (S3), it is assumed that stable idling operation has occurred, and the operation of the pulse width correction means 14 is canceled and the fuel injector 7 A pulse signal having a basic pulse intensity T calculated based on the detected value of the air flow meter 4 is output (S6).

Further, when the engine speed exceeds the idle speed (S3), when the idle switch 6 is turned off (S4
), it is assumed that the output has been increased in accordance with the load from the M speed operation, the operation of the pulse width correction means 14 is canceled, and the basic pulse width calculated based on the detected value of the air flow meter 4 is applied to the fuel injector 7. A pulse signal having a pulse width TP is output (S6).

In addition, as shown in Fig. 4, the basic pulse width T P I D L is learned and memorized by confirming that the water temperature of the engine 1 is above a predetermined value and that the engine 1 is sufficiently warmed up. , 1. 1111 confirms that the idle switch 6 is on (S12), and sets the rotation speed N. is 1
516), read the basic pulse width T at that time (513), repeat this reading a predetermined number of times (S14), calculate the total average value, and use this calculation result as the basic pulse width at idle. Pulse width TP
I. , (S15).

In addition, in one of the above implementations, the basic pulse width T during deceleration operation is
P.I. are set by learning, but of course, the predetermined basic pulse widths T, , OL may be written (1) without relying on such learning.

〔Effect of the invention〕

As described above, the engine fuel supply device according to the present invention changes the fuel supply amount during deceleration operation to the fuel supply amount during idling operation corresponding to the opening degree of the throttle valve, regardless of the detected value of the air flow meter. Since the above control is performed, it is possible to reliably prevent excess or deficiency in the amount of supplied fuel caused by inertia or detection deviation of the air flow meter, and the occurrence of engine stall due to this.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram schematically showing an embodiment of the present invention, and FIG.
The figure is a block diagram of the electronic control unit, Figure 3 is a flowchart showing the flow of the main part of the control sequence of the electronic control unit, and Figure 4 is a flowchart showing the flow of the operation of part 1 of the learning record. . In the figure, 1 is an engine, 4 is an air flow meter, and 9 is a lower limit setting means (electronic control unit).

Claims (1)

[Claims] 1. In an engine fuel supply system in which the amount of fuel supplied is controlled according to the output of a vane-type air flow meter that detects the amount of intake air, the amount of fuel supplied during deceleration is controlled to be greater than the amount of fuel supplied during idling operation. A fuel supply device for an engine, characterized in that a lower limit setting means is provided.