JPH01237338A - Air flow control device for internal combustion engine idling - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a control device for the flow rate of air taken into an internal combustion engine when it is idling.

<Prior Art> Conventionally, intake air flow rate control during idling in an engine intake system has been performed, for example, as follows.

In other words, after warm-up is completed, the opening degree of the idle speed control valve, which is installed in a passage that bypasses the throttle valve, is adjusted to control the idle speed to a target speed that achieves stable rotation while reducing fuel consumption. feedback control (
(See Japanese Patent Application Laid-Open No. 59-211738, etc.).

Also, since a large air flow rate is required during startup and warm-up, a throttle opener is installed that senses the engine temperature and opens the throttle valve when the engine temperature is low.The air flow rate is ensured by both the throttle opener and the idle speed control valve. are doing. Furthermore, some vehicles are equipped with a fast idle control valve that increases the flow rate of air that bypasses the throttle valve, in addition to the idle speed control valve, when warming up or when a large external load such as an air conditioner or power steering is applied.

It is possible to control these various types of air flow with a single large-capacity control valve, but if a failure occurs that causes the valve to be stuck in the fully open position, the air flow becomes excessive and various problems occur. Because of this problem, air flow rate control is performed separately for each function as described above.

<Problems to be Solved by the Invention> By the way, such a conventional intake air flow rate control structure has the following problems.

That is, when the fast idle control valve is used during warm-up, the first idle control valve is controlled to be open until a certain water temperature reaches a certain temperature in order to sustain starting at an extremely low temperature, thereby increasing the flow rate of air that bypasses the throttle valve. However, it will be closed after that. When it is closed, the air flow rate is insufficient, causing a large drop in engine speed.

As a result, there is a risk that an engine stall will occur due to a drop in engine speed.

Figure 5 is a time chart showing this state. When the fast idle control valve closes, the engine speed drops, and then the idle speed control valve returns the engine to the target speed by controlling the air flow rate. ing.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional circumstances, it is an object of the present invention to prevent the occurrence of a drop in engine speed when a fast idle control valve is closed.

<Means for Solving the Problem> For this reason, the present invention, as shown in FIG. Based on the control value of the duty ratio of the pulse signal obtained by adding the feedback correction amount set by increasing or decreasing the correction amount to the basic control value (
A pulse signal of the duty ratio is output, and the idle speed control valve, which controls the intake air flow rate of the first auxiliary air passage, bypasses the throttle valve of the engine intake system, and the idle speed control valve opens and bypasses the throttle valve of the engine intake system. In the idle air flow control device for an internal combustion engine, comprising a fast idle control valve that increases the intake air flow rate of a second auxiliary air passage, the integral in the integral control of the feedback correction amount when the fast idle control valve is closed. The configuration includes integral increasing means for increasing the value of integral by a predetermined amount.

<Function> In this configuration, when the fast idle control valve is closed, the air flow rate is equivalent to the air flow rate passing through the fast idle control all valve, or the air flow rate is such that the rotational speed drops to an allowable level. The value of the integral in the integral control of the feedback correction amount is uniformly increased, and a drop in engine speed is prevented.

<Example> Embodiments of the present invention will be described below based on the drawings.

In Fig. 2, the valve stem of a throttle valve 2 installed in an intake passage 1 of an internal combustion engine is connected to a temperature-sensitive member (such as a silicone pellet) that detects engine water temperature and causes thermal displacement. A throttle opener 3 is attached as a warm-up air flow rate control means for adjusting the opening degree of the engine.

An idle speed control valve 5 is interposed in a first auxiliary air passage 4 which is provided to bypass the throttle valve 2 interposed in the intake passage 1 .

This idle speed control valve 5 compares the target rotation speed set based on the engine operating state with the actual engine rotation speed, increases or decreases the feedback correction amount by integral control, and sets the feedback correction amount to the basic control value. A pulse signal having a duty ratio based on the duty ratio control value of the pulse signal obtained by adding the above is output, and the intake air flow rate of the first auxiliary air passage 4 is controlled.

In addition, the second auxiliary air passage 6, which is provided by bypassing the throttle valve 2, is configured to maintain the idle rotation speed in response to an increase in the electrical load on the vehicle during warm-up or engine idling, and external loads such as air conditioner operation. A fast idle control valve 7 is interposed to increase the correction.

Here, the idle speed control valve 5 and the fast idle control valve 7 are connected to an output terminal of a control unit 8, and the control unit 8 includes a throttle sensor 9. Vehicle speed sensor 10° for detecting vehicle speed; rotation speed sensor 11 for detecting engine speed. Water temperature sensor 12 for detecting cooling water temperature. Each signal from the air conditioner switch 13 is input, and the opening degree of the idle speed control valve 5 and the opening/closing of the fast idle control valve 7 are controlled according to the engine operating state detected by these signals.

The control unit 8 is also equipped with integral increasing means for increasing the integral value in the integral control of the feedback correction amount of the idle speed control valve 5 by a predetermined amount when the fast idle control valve 7 is closed.

This control routine will be explained according to the flowchart in FIG.

In step (hereinafter abbreviated as S along with the figures) 1, the fast idle control valve 7 is turned on and the second auxiliary air passage 6 is opened.

In S2, it is determined whether the OFF condition for the fast idle control valve 7 is satisfied, and the control valve 7 is OFF, that is,
Determine whether the closing operation has been performed.

If the OFF condition for the fast idle control valve 7 is satisfied (YES), the process proceeds to S3, where the air flow rate is set to be equal to the air flow rate passing through the fast idle control valve 7, or the engine speed is reduced to an allowable level. The value of the integral (1 minute) in the integral control of the feedback correction amount is increased by a predetermined amount so that the air flow rate becomes equal to the air flow rate.

As a result, when the fast idle control valve 7 is turned off, there is no shortage of air flow (and a large drop in rotational speed can be prevented (see FIG. 4)).

Therefore, it is possible to eliminate the possibility of engine stalling due to a drop in rotational speed.

In addition, in the auxiliary air flow rate control using the idle speed control valve 5, the correlation with the target rotation speed can be determined by learning the feed puncture/punk correction amount, setting the learning correction amount, and using this to correct the basic control value. In the case where so-called idle speed learning control is performed, the learning control is canceled for a predetermined time when the value of the integral (1 minute) is increased by a predetermined amount.

(Effects of the Invention) As described above, according to the present invention, in the idle air flow rate control device for an internal combustion engine, which includes an idle speed control valve and a fast idle control valve, the fast idle control valve When closed, the value of the integral in the integral control of the feedback correction amount increases uniformly so that the air flow rate is equivalent to the air flow rate passing through the fast idle control valve, or the air flow rate is such that the rotational speed drops to an acceptable level. This prevents the engine speed from dropping and prevents the possibility of engine stalling.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to claims of the present invention, Fig. 2 is a configuration diagram of an embodiment of the present invention, Fig. 3 is a flowchart showing a control routine of the same embodiment, and Fig. 4 is a fast idle control valve of the present invention. A time chart showing the relationship between the operating state, the integral of the idle speed control valve, and the engine speed. Figure 5 is a time chart showing the relationship between the operating state of the conventional fast idle control valve, the integral of the idle speed control valve, and the engine speed. It is a chart.

Claims (1)

[Claims] A pulse signal obtained by comparing the target rotation speed set based on the engine operating state and the actual engine rotation speed, increasing or decreasing the feedback correction amount using integral control, and adding the set feedback correction amount to the basic control value. A pulse signal with a duty ratio based on the duty ratio control value of is output,
an idle speed control valve that controls the intake air flow rate of a first auxiliary air passage that bypasses the throttle valve of the engine intake system; and an idle speed control valve that controls the intake air flow rate of the second auxiliary air passage that opens and bypasses the throttle valve of the engine intake system. In the idle air flow control device for an internal combustion engine, the air flow rate control device for an internal combustion engine includes a first idle control valve that increases an integral value of the integral in the integral control of the feedback correction amount by a predetermined amount when the fast idle control valve is closed. An air flow rate control device for an internal combustion engine during idling, characterized in that an increasing means is provided.