JPH06294337A - Control method of idle revolution - Google Patents

Abstract

PURPOSE:To realize good start feeling at all times by detecting atmospheric pressure at the time start, determining atmospheric pressure correction amount at the time of start by the detected atmospheric pressure, and determining opening degree of a flow rate control valve by the determined atmospheric pressure correction amount and various correction amounts. CONSTITUTION:Cranking is started by turning an ignition switch on. When it is judged that start begins, the control advances from step 52 to steps 53, 54, 55, 56 in this order, the initial value of correction amount alpha at the time of start which corresponds to atmospheric pressure at the time of start is determined, and the duty ratio of a flow rate control valve is determined based on the sum of the initial value and other correction amount to execute the control of the idle revolution at the time of start. Since the initial value of correction amount alpha at the time of start differs depending on atmospheric pressure the whole correction amount at the time of start is not constant and changes each time. After this, upon completion of complete combustion, the control advance to steps 51, 61, 56 in this order, the duty ratio after start is calculated per the predetermined time, and opening degree of the flow rate control valve is adjusted based on the result. The correction amount alpha at the time of start is reduced gradually to control so that target idle revolution is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an idle speed control method for an automobile engine.

[0002]

2. Description of the Related Art Conventionally, an idle speed control method for controlling an engine speed during idling by controlling an opening of a flow control valve provided in a bypass passage bypassing a throttle valve is disclosed in, for example, Japanese Unexamined Patent Publication No. As in the engine idle speed control device described in Japanese Patent No. 194146, a predetermined air amount is increased and corrected when the engine is started, and
It is known that the amount of air is gradually reduced after the number of engine revolutions reaches a reference number of revolutions to obtain good startability. That is, at the time of starting, the flow control valve is opened to a preset opening degree,
The amount of air supplied from the bypass passage is increased.

[0003]

By the way, in the above-mentioned structure, as shown in FIG. 5, normally, the engine does not reach the idle speed immediately after starting, but once reaches a high speed equal to or higher than the idle speed. There is a so-called overshoot phenomenon in which the engine starts up and then settles down to the idle speed. Further, the amount of air taken in is closely related to the atmospheric pressure, and even if the opening of the flow control valve is the same, the amount of air decreases when the atmospheric pressure is low compared to when the atmospheric pressure is high. In the above, the amount of air to be increased at the time of starting (correction amount at the time of starting) is preset irrespective of changes in atmospheric pressure, and the same amount of air is always corrected in flatland and highland. is not. In other words, in high altitudes where the atmospheric pressure is low, the amount of air that is increased is smaller than in flat ground, and the maximum rotation speed at start and the minimum rotation speed also decrease, reducing the feeling of complete explosion. On the contrary, in a place where the atmospheric pressure is high, the overshoot phenomenon is promoted, which may impair the smooth starting feeling. The present invention aims to solve such a problem.

[0004]

The present invention takes the following means in order to achieve such an object. That is, in the idle speed control method according to the present invention, a flow rate control valve is provided in a bypass passage bypassing the throttle valve, and the opening degree of the flow rate control valve is controlled based on various correction amounts including the warm-up correction amount. In the idle speed control method that controls the engine speed during idling by adjusting the intake air amount, the atmospheric pressure is detected at the time of starting, and the atmospheric pressure correction amount at the time of starting is detected based on the detected atmospheric pressure. It is characterized in that the opening degree of the flow control valve is determined based on the determined atmospheric pressure correction amount and the various correction amounts.

[0005]

With such a structure, the atmospheric pressure is detected at the time of starting, the atmospheric pressure correction amount at the time of starting is determined by the detected atmospheric pressure, and the opening of the flow control valve is determined by the determined atmospheric pressure correction amount. Therefore, the intake air amount at the time of starting changes depending on the level of the atmospheric pressure. Therefore, even in an area where the atmospheric pressure is low, such as a highland, a sufficient amount of air at the time of starting is supplied, and the startability in such an area is improved. On the other hand, on a level ground, on the other hand, even when the atmospheric pressure is high, it is possible to prevent an overshoot or the like at the time of starting due to an excessive correction amount, and always to ensure good starting performance.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. An engine 100 schematically shown in FIG. 1 is for an automobile, and a throttle valve 2 that opens and closes in response to an accelerator pedal (not shown) is provided in an intake system 1 thereof, and a bypass that bypasses the throttle valve 2 is provided. A passage 3 is provided, and a flow control valve 4 for idle speed control is provided in the bypass passage 3. The flow control valve 4 is
It is an electronic switching type abbreviated as VSV, and its substantial opening can be changed by controlling the duty ratio DISC of the drive voltage applied to its terminal 4a, whereby the bypass passage 3 The air flow rate can be adjusted. That is, the bypass passage 3
And a pair of the flow rate control valve 4, the bypass system path that is normally provided for each correction item is unified, and the duty ratio DISC includes them and the warm-up correction amount is increased. It is determined by adding and subtracting the water temperature correction amount, the starting correction amount, the rotation feedback correction amount, and the like.

The intake system 1 is further provided with a fuel injection valve 5, and the fuel injection valve 5 and the flow rate control valve 4 are controlled by an electronic control unit 6. The electronic control unit 6 is mainly composed of a microcomputer system including a central processing unit 7, a storage unit 8, an input interface 9 and an output interface 11. Then, the input interface 9 receives the intake pressure signal a output from the intake pressure sensor 13 for detecting the pressure in the surge tank 12 and the engine speed NE.
The rotation speed signal b output from the rotation speed sensor 14 for detecting the vehicle speed, the vehicle speed signal c output from the vehicle speed sensor 15 for detecting the vehicle speed, and the idle switch 16 output for detecting the open / closed state of the throttle valve 2. The LL signal d, the water temperature signal e output from the water temperature sensor 17 for detecting the engine cooling water temperature as the engine temperature,
An atmospheric pressure signal f output from an atmospheric pressure sensor 18 arranged near the air cleaner upstream of the throttle valve 2 for detecting the atmospheric pressure is input. Further, from the output interface 11, a drive signal g corresponding to the calculated fuel injection time is supplied to the fuel injection valve 5, and a control signal based on a calculated duty ratio DISC described later is supplied to the flow rate control valve 4. h is output respectively. Although not shown, the electronic control unit 6 has a built-in A / D converter for converting an input analog signal into digital data, and converts cooling water temperature and atmospheric pressure into digital data at regular intervals. It is then output to the central processing unit 7.

The electronic control unit 6 determines the fuel injection valve opening time by using the respective signals from the intake pressure sensor 13 and the revolution speed sensor 14 as main information in the operation after warming up, and the fuel injection is performed by the determination. A program for controlling the valve 5 to inject the fuel according to the engine load from the fuel injection valve 5 into the intake system 1 is incorporated. In addition, by controlling the opening degree of the flow rate control valve 4 provided in the bypass passage 3 bypassing the throttle valve 2 based on various correction amounts including the warm-up correction amount to adjust the intake air amount, idling In order to control the engine speed, the atmospheric pressure is detected at the time of starting, and the atmospheric pressure correction amount at the time of starting is determined based on the detected atmospheric pressure. Based on the determined atmospheric pressure correction amount and the various correction amounts described above. A program for idle speed control programmed to determine the opening of the flow control valve is also incorporated.

FIG. 2 shows a schematic structure of this idle speed control program. First, in step 51, it is determined whether or not the engine is starting, and if it is starting, step 52
If not, go to step 61. The determination itself at the time of starting may be the same as a conventionally known method, and by monitoring the output interval of the ignition pulse to the spark plug 19 from the time when the starter (not shown) rotates to start cranking. When the complete explosion is judged and the complete explosion is completed, the start time is set. In step 52, the atmospheric pressure at that time is detected (read) based on the atmospheric pressure signal f output from the atmospheric pressure sensor 18,
In step 53, the initial value of the starting correction amount α is determined according to the detected atmospheric pressure. The initial value of the correction amount α at the time of starting is set in advance in a map corresponding to the level of the atmospheric pressure, and as shown in FIG. 3, becomes smaller as the atmospheric pressure becomes higher, that is, inversely proportional to the atmospheric pressure. It has been set to a numeric value. Next, at step 54, a correction amount other than the start-up correction amount with respect to atmospheric pressure is dealt with in response to the engine operating condition at that time, for example, in response to an air conditioner (air conditioner) load, a trick converter (torque converter) load, and the like. decide.

In step 55, the initial value of the correction amount α at startup determined in step 53 and the other correction amounts determined in step 54 are summed, and the opening of the flow control valve 4 corresponding to the summed correction amount. (Starting ISC opening) is determined (FIG. 4). Then, the duty ratio of the drive signal of the flow control valve 4 is calculated based on the determined opening degree. In step 56, the drive signal of the calculated duty ratio is output to the flow rate control valve 4, and the correction air at the time of starting, which is corrected according to the atmospheric pressure via the bypass passage 3, is used as the surge tank 12.
Is supplied to. Further, in step 61, the duty ratio after starting is calculated. This duty ratio calculation itself is
It may be the same as the conventional one, for example, the water temperature at that time,
The correction amount may be sequentially decreased from the correction amount α at startup based on the engine speed, the open / closed state of the idle switch 16, and the like.

In the above construction, when the ignition switch is turned on and cranking is started, the control proceeds to step 51, and when it is determined that the engine is starting, steps 52 → 53 → 54 → 55 → 56. Then, the initial value of the starting correction amount α corresponding to the atmospheric pressure at the time of starting is determined, and the duty ratio of the flow control valve 4 is determined from the total value of the initial value and other correction amounts. Executes idle speed control. Since the initial value of the starting correction amount α differs depending on the atmospheric pressure, the entire starting correction amount is not constant but changes each time. That is, in the highland, the entire correction amount at the time of starting increases because the initial value of the correction amount at the time of starting becomes large, and the starting is started with a large amount of air. After this, if the complete explosion is completed,
The control proceeds from step 51 to step 61 to step 56 to calculate the duty ratio after starting every predetermined time,
The opening degree of the flow rate control valve 4 is adjusted based on the calculation result, and the correction amount α at the time of starting is gradually decreased to control to reach the target idle speed.

Therefore, according to such a structure, in a high altitude where the atmospheric pressure is low, the amount of air supplied through the bypass passage 3 is increased at the time of starting, so that it is possible to prevent the startability from deteriorating. On a flat land where the atmospheric pressure is extremely high, the amount of air supplied is reduced, so that the overshoot phenomenon after starting can be prevented. By this, the highlands,
A good starting feeling can always be obtained regardless of the flat ground.

The present invention is not limited to the embodiments described above. For example, in the above embodiment, the determination of the correction amount at startup α is made based on the map, but it may be made by calculating every time the atmospheric pressure is detected.
Further, after the start, the start correction amount α may be decreased by a predetermined amount every predetermined time. In this case, in the operation in the highland, it takes a little longer until the target idle speed is reached than in the case of the flatland. Besides, the configuration of each unit is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0014]

As described above in detail, the present invention determines the correction amount at the time of starting based on the atmospheric pressure at the time of starting.
It is possible to prevent the overshoot phenomenon, suppress the deterioration of the startability at high altitudes, etc., and always obtain a good starting feeling.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the embodiment.

FIG. 3 is a graph showing a change of an initial value of a correction amount at startup in the embodiment with respect to atmospheric pressure.

FIG. 4 is an operation explanatory view of the same embodiment.

FIG. 5 is an operation explanatory view of a conventional example.

[Explanation of symbols]

 2 ... Throttle valve 3 ... Bypass passage 4 ... Flow control valve 6 ... Electronic control device 7 ... Central processing unit 8 ... Storage device 9 ... Input interface 11 ... Output interface

Claims (1)

[Claims] 1. A flow control valve is provided in a bypass passage bypassing a throttle valve, and an opening of the flow control valve is controlled based on various correction amounts including a warm-up correction amount to adjust an intake air amount. Thus, in the idle speed control method that controls the engine speed during idling, the atmospheric pressure is detected at startup, and the atmospheric pressure correction amount at startup is determined based on the detected atmospheric pressure, and the determined atmospheric pressure correction is performed. An idle speed control method, characterized in that the opening of the flow control valve is determined based on the amount and the various correction amounts.