JPH04166638A - Fuel cut controller of electronic control type fuel injection engine - Google Patents

Abstract

PURPOSE:To secure characteristics of engine brake which can sufficiently decrease generation of excessive deceleration shock and conform to requirement of a driver by performing fuel cut of respective cylinders sequentially at lag time differences which match throttle closing speeds. CONSTITUTION:During run of a vehicle, a calculation circuit 18 inside a control unit 17 responds to the output of a throttle opening sensor 13 when it is judged that an acceleration pedal has been operated in release, a throttle valve 2 is operated in its closing direction and a fuel cut condition is present, and cumputes a throttle closing speed alpha from a ratio of difference between the present output value and the previous output value to the measured time difference of each value. A fuel cut signal is outputted after a set fuel cut delay time, and fuel injection by the injector 8a of the first cylinder is cut, and then the fuel injection by the injector 8b of the second cylinder is cut after the lapse of set time corresponding to the throttle closing speed alpha, and similarly thereafter the fuel injection by the injectors 8c, 8d of third and fourth cylinders is cut sequentially every lapse of the delay time.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an electronically controlled fuel injection engine that has engine braking characteristics that match the actual state of the driver's accelerator operation during deceleration when the accelerator is operated in the release direction. The present invention relates to a fuel cut control device that can be obtained.

[Conventional technology]

This type of fuel cut control device divides all cylinders into multiple groups when the accelerator is released during deceleration operation and fuel cut conditions such as engine speed, water temperature, etc. exceed set values. The fuel in the cylinders is sequentially cut at a predetermined time lag to cause the engine to generate engine braking torque by running the engine dry (for example, see Japanese Patent Laid-Open No. 61-23843).

[Problem to be solved by the invention]

Such fuel cut control technology takes exhaust gas purification and fuel efficiency into particular consideration, and cutting at different times is an advantageous shock reduction deceleration method, but when driving a turbocharged vehicle, releasing the accelerator causes the throttle to close. The problem is that the deceleration varies depending on the speed, and the fuel cut for each cylinder or group of cylinders is performed at a certain time difference, making it impossible to obtain engine braking characteristics that correspond to the driver's accelerator operation. was there.

The present invention solves this problem by reducing the deceleration shock by sequentially cutting the fuel in each cylinder with a time difference that corresponds to the driver's actual accelerator operation. It is an object of the present invention to provide a fuel cut control device for an electronically controlled fuel injection engine that allows engine braking characteristics to be obtained.

[Means to solve the problem]

To achieve this object, the present invention provides a multi-point injection type fuel injection control device having an injector for each cylinder, in which a fuel cut determination signal is generated in response to a vehicle driving state detection signal, and a fuel cut determination signal is generated based on a throttle opening value. An arithmetic circuit that calculates a throttle closing speed value, a timer that sets a delay time corresponding to the throttle closing speed value by this arithmetic circuit, and a The present invention is characterized by comprising means for sequentially cutting off fuel injection by the injectors of the cylinders.

[For production]

With the above configuration, when the arithmetic circuit outputs the fuel cut determination signal in response to the vehicle driving state detection signal, the fuel in each cylinder is sequentially cut, but this fuel cut depends on the throttle closing speed. Since the throttle closing speed is linked to the driver's accelerator release operation, the engine braking torque characteristics based on the fuel cut for each cylinder match the driver's accelerator operation, preventing unexpected deceleration. No shock.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, to explain the case where the present invention is applied to a horizontally opposed four-cylinder multi-point fuel injection engine, a throttle body 1 has a throttle valve 2,
The intake pipe 3 upstream thereof communicates with an air flow meter 5 immediately downstream of the air cleaner 4. The downstream side of the throttle body 1 communicates with an engine main body 7 via an intake manifold 6, and injectors 8a to 8d are attached to the first to fourth cylinders in the engine main body 7.

As the fuel system of the injector, the negative pressure of the fuel tank 9, the fuel pump IO9, each injector 8a to 8d, and the intake manifold 6 acts, and the fuel goes back to the fuel tank via the pressure regulator 11 that adjusts the difference between the intake pipe pressure and the fuel pressure to a constant level. A circulation path 12 returning to the injector 9 is configured, and the fuel pressure of the injectors 8a to 8d is always maintained at a constant value higher than the internal pressure of the intake manifold 6, and the fuel injection amount is controlled by the injection time.

In addition, the control unit 17 receives the intake air amount signal from the air flow meter 5, the throttle opening sensor 13, the signal from the engine rotation speed sensor 15 based on the pulse signal of the ignition coil, etc., and calculates the injection time. Each injector 8a is controlled by the injection time signal from the control unit 17.
8d works.

The basic configuration of the control system will be explained with reference to Figure 2.
An arithmetic circuit 18 in the control unit 17 calculates the basic pulse width of fuel injection based on the intake air amount Q measured by the air flow meter 5 and the engine speed N measured by the engine speed sensor 15, It is corrected by signals from the sensor 16 and other correction elements and outputs a fuel injection pulse width signal Sr. This fuel injection pulse width signal S' is determined by the cylinder selection circuit 19 from the drive circuits 20a to 20d of the respective injectors 8a to 8d.
are sequentially applied to each injector 8a to 8d to inject fuel.

Then, the accelerator pedal is released, the throttle valve 2 is operated in the closing direction, and the vehicle speed sensor 14, the engine rotation speed sensor 15. Based on the output of the water temperature sensor IB, the vehicle speed,
If the engine speed and water temperature are each greater than a predetermined set value, the arithmetic circuit 18 determines a fuel cut. Further, the arithmetic circuit 18 calculates the throttle closing speed α in response to the output Thr of the throttle opening sensor 13, and when the arithmetic circuit 18 changes the output Thr of the throttle opening sensor 13 from analog to digital, it calculates the current The throttle closing speed α is calculated from the ratio of the difference between the output value Thr and the previous output value Thro and the time difference between the measurements of each value.

When determining the fuel cut, the arithmetic circuit 18 outputs a fuel cut signal Sfc after a preset fuel cut delay time Tdc.
The fuel cut signal S'e is introduced into the first cylinder injector drive circuit 20a via the cylinder selection circuit 19, and cuts the fuel injection by the first cylinder injector 8a.At this time, the cylinder selection circuit 19 The timer 21 is activated by receiving a signal from the timer 21.

A time Tdα corresponding to the throttle closing speed α is set by the calculation circuit 18 from the memory table 22 regarding the relationship between the throttle closing speed and the delay time, and the timer 21 gives a signal to the cylinder selection circuit 19 when this set time Thα has elapsed. Accordingly, the cylinder selection circuit 19 cuts fuel injection by the injector 8b of the next second cylinder. After that, in the same way, the third. 4th cylinder injector 8c, li
d is sequentially cut off every time the delay time Tdα elapses.

In this way, the fuel injection of each cylinder is sequentially cut-controlled, but the delay time Thα between the fuel cuts of each cylinder is determined according to the throttle closing speed α that depends on the driver's accelerator operation, so that the driver slowly When the accelerator is operated, that is, when the throttle closing speed α is small, a sudden engine brake operation is not desired. The number of cylinders in which fuel is cut is controlled to increase, and engine braking force is generated in accordance with the driver's actual accelerator operation. When the throttle closing speed is high, as shown in FIG. 3(b), the delay time becomes short, and engine braking characteristics suitable for sudden accelerator operation by the driver are obtained.

While fuel is being sequentially cut off from each cylinder, the throttle valve 2 may be operated in the direction of opening again or the vehicle speed may drop below a predetermined value, causing the throttle opening sensor 18 to open. When a signal corresponding to the fuel injection return condition is generated in the vehicle speed sensor 14 or the like, the arithmetic circuit 18 returns the injectors 8a to 8d of each cylinder to fuel injection operation.

Note that in the above embodiment, the delay time Tdα between each cylinder is the same value and the fuel is sequentially cut. Alternatively, since the throttle closing speed associated with the accelerator release operation is generally not constant, the fuel cut delay time for each cylinder may be set according to the throttle closing speed during the throttle valve closing process. You may change it.

〔Effect of the invention〕

Since the present invention is configured as described above, the fuel cut of each cylinder is performed sequentially with a delay time difference corresponding to the throttle closing speed. The occurrence of excessive deceleration shock can be sufficiently reduced, engine braking characteristics that meet the driver's requirements can be obtained based on the actual state and situation of the driver's accelerator operation, and smooth deceleration control can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of an engine to which the present invention is applied, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing the operation status of fuel cut for each cylinder. 8a to 8d... Injectors for the first to fourth cylinders, 17
...Control unit, 18...Arithmetic circuit, ■9...
Cylinder selection circuit, 21... timer. Patent Applicant Fuji Heavy Industries Co., Ltd. Agent Patent Attorney Nobu Kobashi Slag amount Patent Attorney Wataru Kokura

Claims (1)

[Claims] In a multi-point injection type fuel injection control device having an injector for each cylinder, a fuel cut determination signal is generated in response to a vehicle driving state detection signal, and a throttle closing speed value is determined from a throttle opening value. a timer that sets a delay time corresponding to the throttle closing speed value by this calculation circuit; 1. A fuel cut control device for an electronically controlled fuel injection engine, comprising means for sequentially cutting fuel injection.