JPH0337350A - Fuel controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent lean conditions of air-fuel ratio at the time of fuel supply reset in a device in which fuel cutting is performed at the time of deceleration of an internal combustion engine by performing controlling so as to enable fuel supply for only a specified time in response to a fuel cut time while cutting fuel at the deceleration operation time. CONSTITUTION:At the operation time of an internal combustion engine 2, in an ECU 38, fuel injection from a fuel injection valve 10 is calculated based on output signals from an intake temperature sensor 30, an opening rate sensor 32, an water temperature sensor 34, a pressure sensor 36, a turning angle sensor 40, an O2 sensor 42 and the like. The fuel injection is controlled so that the air-fuel ratio of mixed air is converged to a target value. At the deceleration operation time of the engine 2, fuel cut is performed so as to aim at improvement of fuel consumption, decrease of exhaust hazardous component and the like. In this case, it is judged whether the specified fuel cut time is passed or not at the time of cutting fuel. When it is YES, the fuel injection is performed for only a specified time set according to the fuel cut time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel control device for an internal combustion engine, and in particular, to a fuel control device for an internal combustion engine that can prevent the air-fuel ratio from becoming lean when the internal combustion engine returns to steady operation from deceleration operation. The present invention relates to a fuel control device for an internal combustion engine that can prevent destabilization of idle speed and avoid engine stall.

[Conventional technology]

Some internal combustion engines cut fuel during deceleration operation in order to improve fuel consumption rate, reduce harmful exhaust gas components, and the like. However, since fuel is cut during deceleration operation, when the deceleration operation returns to steady operation, the air-fuel ratio becomes lean and the idle speed becomes unstable, which may cause engine stall.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 63-235636, by immediately restarting fuel supply when the fuel return condition is satisfied during fuel cut, the idle speed becomes unstable due to lean air-fuel ratio. Some attempts have been made to prevent this and avoid engine stall.

[Problem that the invention seeks to solve]

By the way, when the internal combustion engine returns to steady operation from deceleration operation, especially in internal combustion engines equipped with a single-point injection type fuel supply system, the fuel supply is interrupted because the intake passage from the injection valve to the combustion chamber is long. As a result, the air-fuel ratio becomes significantly leaner. For this reason,
In order to stabilize the idle speed and prevent engine stalling when normal operation is resumed, there is a system that immediately starts supplying fuel or supplies an increased amount of fuel, as disclosed in the above-mentioned publication.

However, if the fuel cut time during deceleration operation becomes longer,
Because the inside of the intake pipe becomes dry, it takes time for the fuel that starts to be supplied when normal operation is resumed to reach the combustion chamber, causing a delay in fuel supply, making the air-fuel ratio even leaner, and reducing the idle speed. This has the disadvantage of causing instability in the rotational speed and engine stall.

In addition, if the cooling water temperature or intake air temperature is low, fuel atomization will worsen and fuel supply delays will be exacerbated, leading to an even leaner air-fuel ratio and a drop in idle speed. The situation is severe with regard to engine stalls and engine stalls.

[Purpose of the invention]

Therefore, an object of the present invention is to prevent the air-fuel ratio from becoming lean when the internal combustion engine returns from deceleration operation to steady operation,
An object of the present invention is to realize a fuel control device for an internal combustion engine that can prevent destabilization of the idle speed and avoid engine stall.

[Means for solving problems]

In order to achieve this object, the present invention provides a fuel control device for an internal combustion engine that performs control to cut fuel during deceleration operation of the internal combustion engine. The present invention is characterized in that a control means is provided for controlling fuel supply for a predetermined period of time.

[Effect]

According to the configuration of the present invention, the control means controls it'l+ to supply fuel for a predetermined period of time according to the fuel cut time during fuel cut during deceleration operation of the internal combustion engine, so that the internal combustion engine can stop the deceleration operation. It is possible to prevent the air-fuel ratio from becoming lean when normal operation is resumed.

〔Example〕

Next, embodiments of the present invention will be described in detail based on the drawings.

1 to 5 show an embodiment of the present invention. In FIG. 0, 2 is an internal combustion engine, and 4 is a fuel control device. This internal combustion engine 2 is equipped with a single point injection type fuel supply device. That is, in the intake passage 6 of the internal combustion engine 2, in order from the upstream side, an air cleaner 8, a fuel injection valve 10 forming a fuel system, an intake throttle valve 12,
is provided. The air taken in from the air cleaner 8 is mixed with fuel injected and supplied from the fuel injection valve 1O to generate an air-fuel mixture, which is metered by the intake throttle valve 12 and taken into the combustion chamber 14, where it is combusted. Exhaust gas produced by combustion is exhausted to the outside through the exhaust passage 16.

The fuel injection valve 10 is communicated with a fuel tank 20 through a fuel supply passage 18. The fuel in the fuel tank 20 is
The fuel is supplied to the fuel injection valve IO by the fuel pump 22 via the fuel supply passage 18. The fuel supply passage 18 is
A fuel return passage 26 communicates with the fuel tank 20 via a fuel pressure regulator 24 . Fuel pressure regulator 2
4 introduces intake pressure through a fuel pressure adjustment pressure introduction passage 28 communicating with the intake passage 6 on the downstream side of the intake throttle valve 12, adjusts the fuel pressure to a predetermined pressure, and drains excess fuel into the fuel return passage 26. is returned to the fuel tank 20.

The intake passage 6 includes an intake temperature sensor 30 that detects the intake air temperature, a throttle opening sensor 32 that detects the opening state of the intake throttle valve 12, a water temperature sensor 34 that detects the cooling water temperature, and an intake air temperature sensor 34 that detects the intake air pressure. A pressure sensor 36 for detection is provided. These various sensors 30 to 36 are connected to the input side of a control section 3B, which is a control means of the fuel control device 4.

Further, on the input side of this control unit 38, there is a rotation angle sensor 40 provided in the internal combustion engine 2 that detects the rotation angle, and an exhaust path! 16
An 02 sensor 42, which is an exhaust sensor that detects exhaust component values provided in , the air conditioner 5°, the power steering section 52, the starter section 54, the test terminal section 56, the battery 58, and the main relay 60 are connected. Note that the ignition coil/igniter 44 is also connected to the output side of the control section 38.

On the other hand, the fuel injection valve 10 is connected to the output side of the control section 38, and the fuel pump 22 is also connected via a pump relay 62.

Further, on the output side of the control section 3B, a diagnosis lamp 64 and a bypass air control valve 68 for controlling the amount of bypass air in a bypass passage 66 that communicates the upstream and downstream sides of the intake throttle valve 12 of the intake passage 6 are provided. , E that communicates with the downstream side of the intake throttle valve 12 of the intake passage 6 and the EGR valve (not shown).
A pressure regulating valve 72 that adjusts the introduction pressure of the GR valve control pressure introduction passage 70 is connected.

As a result, the control unit 38 of the fuel control device 4 receives input signals from various sensors 30 to 36 and devices 40 to 60 such as engine speed, ignition pulse, cooling water temperature, intake air temperature, etc., as shown in FIG. Manually adjust the throttle opening, etc., operate the fuel injection valve 10 to inject and supply fuel to the internal combustion engine 2, and then
2 sensor 42 is input to control the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine 2 to converge to a target value, and also to perform fuel cut during deceleration operation of the internal combustion engine 2.

That is, during deceleration operation of the internal combustion engine 2, fuel is cut as shown in FIG. 3(B) in order to improve the fuel consumption rate and reduce harmful exhaust components. However, due to this fuel cut, the air-fuel ratio becomes lean as shown in FIG. 3(D). At this time, the engine speed drops as shown in Fig. 3 (A), but conventionally, when the engine speed returns to the normal speed due to clutch OFF, the engine speed drops as shown by the broken line in Fig. 3 (B). By increasing the basic injection amount of fuel that is supplied after recovery, the aim is to stabilize the idle speed and avoid engine stall. In addition, during deceleration operation, Fig. 3 (C)
As shown in the figure, the ignition pulse is supplied without being cut.

However, if the fuel cut period becomes long, especially in the case of an internal combustion engine 2 equipped with a single-point fuel injection valve IO, the inside of the intake pipe will become completely dry, and the fuel will be restored and fuel will not be supplied. However, as the supplied fuel adheres to the intake pipe wall, the time required for the air-fuel ratio to become lean is promoted and becomes longer, resulting in a delay in enriching the air-fuel ratio, as shown by the solid line in Figure 3 (D). , as shown by the broken line in FIG. 3(A), the engine speed drops excessively, resulting in instability of the idle speed and engine stall.

Therefore, in the fuel control device 4 of the internal combustion engine 2 that performs control to cut fuel during deceleration operation of the internal combustion engine 2, the control unit 3
8, by controlling to supply fuel for a predetermined time t according to this fuel cut time T during fuel cut during deceleration operation of the internal combustion engine 2, when the internal combustion engine 2 returns from deceleration operation to steady operation. This prevents the air-fuel ratio from becoming lean.

Next, the effect will be explained.

As shown in FIG. 4, the control unit 38 controls the star 1 (1
00) Then, it is determined (101) whether or not fuel is being cut due to deceleration operation of the internal combustion engine 2. If NO,
It becomes the end (104).

If YES in step 101, it is determined whether fuel cuff time T has elapsed (102). If No, it becomes the end (104).

If YES in step 102, see FIG. 3(B).
As shown by the solid line, the fuel injection valve 10 is operated by supplying an injection pulse for a predetermined time t, fuel is injected and supplied to the internal combustion engine 2, and the end (104) is reached.The predetermined time t is
This is a value that is set according to the fuel discharge time T.

In this way, by controlling fuel supply for a predetermined time t according to the fuel supply time T during fuel cut during deceleration operation of the internal combustion engine 2, when the internal combustion engine 2 returns from deceleration operation to steady operation, It is possible to prevent the air-fuel ratio from becoming lean by eliminating dryness of the intake pipe wall.

Therefore, as shown by the solid line in FIG. 3(A), it is possible to prevent the idle speed from becoming unstable due to the lean air-fuel ratio.
Engine stall can be avoided. Further, since the problem can be dealt with by simply changing the program in the control unit 38, there is no need to add additional parts, the structure does not become complicated, and the cost can be kept low, which is economically advantageous.

Note that when the cooling water temperature and intake air temperature are low, such as when the internal combustion engine 2 is cold, the air-fuel ratio is further reduced, so the predetermined time t is increased when the engine is cold, as shown in FIG. By tabulating the predetermined time t with respect to the cooling water temperature and intake air temperature and performing fine control, it is possible to more effectively stabilize the idle speed and avoid engine stall.

Further, the injection pulse supplied to the fuel injection valve lO for the predetermined time t may not be continuous, but may be divided into several pulses and supplied to the fuel injection valve 10 to supply fuel. Furthermore, after fuel has been supplied for a predetermined time t, if the fuel cut time T has elapsed again, by controlling to supply fuel again for a predetermined time t, the idle speed can be more effectively stabilized. Engine stall can be avoided. In other words, if the fuel cut time is long, if fuel is supplied for a predetermined time t at one time during the fuel cut, the intake pipe wall will dry before recovery, so the control is controlled so that fuel is repeatedly supplied for a predetermined time t. By doing so,
It is possible to prevent the air-fuel ratio from becoming lean by eliminating dryness of the intake pipe wall.

(Effects of the Invention) According to the present invention, the control means controls the internal combustion engine to supply fuel for a predetermined period of time according to the fuel cut time during the fuel cut during deceleration operation of the internal combustion engine. It is possible to prevent the air-fuel ratio from becoming lean when returning from deceleration operation to steady operation.

Therefore, it is possible to prevent the idle rotation speed from becoming unstable due to lean air-fuel ratio, and to avoid engine stall.

Further, since the problem can be dealt with by simply changing the program of the control means, there is no need to add additional parts, the structure is not complicated, and the cost can be kept low, which is economically advantageous.

[Brief explanation of drawings]

1 to 5 show embodiments of the present invention, FIG. 1 is a schematic explanatory diagram of a fuel control device for an internal combustion engine, FIG. 2 is a block diagram of a fuel supply system, and FIG. 3 is an engine rotation speed and injection pulse. FIG. 4 is a control flowchart, and FIG. 5 is a diagram showing the relationship between temperature and predetermined time. In the figure, 2 is an internal combustion engine, 4 is a fuel control device, 6 is an intake passage, 10 is a fuel injection valve, 12 is an intake throttle valve, 16 is an exhaust passage, 30 is an intake temperature sensor, 32 is an opening sensor, 3
4 is a water temperature sensor, 36 is a pressure sensor, 38 is a control unit, 4
0 is a rotation angle sensor, 42 is a 02 sensor, and 44 is an ignition coil/igniter.

Claims (1)

[Claims] 1. In a fuel control device for an internal combustion engine that controls fuel cut during deceleration operation of the internal combustion engine, control is performed to supply fuel for a predetermined time according to the fuel cut time during fuel cut during deceleration operation of the internal combustion engine. A fuel control device for an internal combustion engine, comprising a control means.