JPH0413542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an engine idle control system that controls the engine idle speed to a target value by adjusting the amount of intake air supplied to the engine. This invention relates to a rotation control device.

[Prior Art] Conventionally, an engine idle speed control device that adjusts the intake air amount of the engine so that the engine speed reaches a target value during idling operation of the engine is well known (for example, (see Japanese Patent Application Laid-Open No. 54-22017), and is generally called a self-idle governor.

By the way, if an engine equipped with this type of self-idle governor is left to idle for a long period of time, such as by leaving it warmed up, misfires may occur and the engine rotation may slow down, despite the control provided by the self-idle governor. May become unstable.

The reason for this is that during idling, the target engine speed is kept as low as possible in order to reduce fuel consumption, and as a result, the number of times the spark plug electrode is scavenged per unit time is reduced, resulting in carbon and gas generated during combustion. The first problem is that unburnt fuel adheres to and accumulates on the electrodes of the spark plug, and these deposits act as resistance, increasing the required voltage of the spark plug and causing ignition failure.

Furthermore, the scavenging performance within the combustion chamber is poor, resulting in poor combustibility and, as a result, rotation becomes unstable.

[Object of the Invention] An object of the present invention is to reliably prevent misfires and unstable rotation caused by continuous idling operation for a long time as described above.

[Structure of the Invention] Therefore, in the present invention, the duration of idling operation is detected, and when the duration becomes longer, the target value of the idling rotation speed is corrected to be higher.
The basic feature is that by increasing the idle speed, the scavenging performance of the combustion chamber of the engine, particularly the electrodes of the spark plug, is improved.

FIG. 1 is an overall configuration diagram of the present invention. In FIG. 1, 1 is an engine, 2 is an intake air amount adjustment valve that adjusts the intake air amount of the engine 1, and 3 is a rotational speed for detecting the engine rotational speed. A detection means 4 is an idle operation detection means for detecting when the engine 1 is idling; 5 is an idle operation detection means for detecting when the engine 1 is idling; 5 is a means for controlling the intake air amount adjusting valve 2 in order to make the engine speed (idle speed) match a target value when the engine is idling; It is a control means for controlling.

In addition to the above-mentioned basic configuration, the present invention includes an idle time accumulating means 6 for accumulating the time since the start of idling operation, and a signal from the idle time accumulating means 6 that is inputted to increase the accumulated time. In some cases, a target value setting means 7 is provided to set the target value higher than when the time is short.

[Effects of the Invention] According to the present invention, when the engine continues to operate idly for a long period of time, such as when the engine is left to warm up, the target value is corrected to a higher side, thereby improving the scavenging performance in the combustion chamber, especially around the plug. It is possible to prevent carbon and unburned fuel from adhering to the electrodes of the plug, and to reliably prevent misfires and unstable rotation.

[Example] Examples of the present invention will be described in detail below.

In the engine 1 shown in FIG. 2, an intake passage 10 supplies intake air to the combustion chamber 12 when the intake valve 11 is opened, and an intake passage 13 supplies exhaust air from the combustion chamber 12 to the outside when the exhaust valve 14 is opened. This is an exhaust passage that discharges air to the surrounding area.

Arranged in the intake passage 10 from the upstream side are an air flow meter 15 that detects the amount of intake air, a throttle valve 16 that opens and closes depending on the amount of depression of an accelerator pedal (not shown), and a fuel injection valve 17. .

A bypass air passage 18 for bypassing the throttle valve 16 is provided in the intake passage 10 from upstream to downstream of the throttle valve 16 held at the idle opening degree, and a bypass air passage 18 is provided in the middle of the bypass air passage 18. An intake air amount adjusting valve 2 is installed in the engine 1 to adjust the amount of intake air supplied to the engine 1 by opening and closing the passage 18 .

The fuel injection valve 17 and the intake air amount adjustment valve 2
is controlled by a control unit 19 using a microcomputer.

This control unit 19 controls the air flow meter 1
5, the engine speed detected by the rotation speed detection means 3, the throttle opening detected by the throttle opening detection means 20 provided for the throttle valve 16, Further, using an on/off signal from a cooler switch 21 provided for a cooler installed in the automobile as an input signal, the fuel injection valve 17 and the intake air amount adjusting valve 2 are controlled as described below.

Of the above two control targets, the control for the fuel injection valve 17 uses the intake air amount and engine rotation speed as basic inputs, and controls the opening/closing time of the fuel injection valve 17,
This is a conventionally known method in which the injection timing is calculated by a program programmed in the control unit 19 in advance.

On the other hand, control of the intake air amount regulating valve 2 is executed according to the flowchart shown in FIG.

This control will be explained with reference to FIG.

Now, when this control flow is started, in step 101, the throttle opening TVθ is first adjusted.
and engine speed Prpm are read. In the next step 102, the read throttle opening TVθ
Based on the engine speed Prpm and the engine speed Prpm, it is determined whether or not the engine is in idle operation. This judgment step 102
When it is determined that the vehicle is idling,
In step 103, it is determined whether the status flag IF indicating the previous operating status is "0" or not, and IF=
If it is 0, the status flag IF is set to "1" in step 104, and the idle time integration value T is set to "0", and then integration is started in step 105 (T←T+1).
In this case, the status flag IF will be “1” from next time onwards.
Therefore, step 104 is skipped and the integration in step 105 is continued.

Then, in the next step 106, a target value Trpm of the idle rotation speed is calculated. This target value
As shown in Figure 4, Trpm is
The parameter is nothing (in this embodiment, the cooler is on/off), and the function f ₁ of the idle time integrated value T is
(T: load). More specifically, when there is no load, the idle time cumulative value is 20
The target value Trpm is maintained at 600 rpm until the target value reaches 600 rpm, and from 20 minutes to 50 minutes, it is increased linearly until it reaches approximately 750 rpm, and after 50 minutes, the target value Trpm is maintained at 600 rpm.
Fixed at 750rpm. In addition, when an external load is applied, compared to the case with no load, approximately
The overall target value is set to around 130-140rpm.

Once the target value Trpm has been set as described above, the target value Trpm is set in step 107.
Deviation between Trpm and actual engine speed Prpm f ₂
(Trpm, Prpm) is calculated, and the opening signal S for the intake air amount regulating valve ₂ is calculated according to this deviation f2.
is calculated, and then in step 108, the opening signal S is applied to the intake air amount adjusting valve 2, the intake air amount adjusting valve 2 is driven, and the required amount of bypass air is set.

This loop will be repeated as long as idling continues, and as mentioned above, if idling continues for more than 20 minutes, the target value Trpm is revised to a higher value, the idle speed is raised, and the engine 1. Scavenging performance is improved. For this reason,
This prevents carbon and unburned fuel from adhering to the spark plug, preventing misfires and unstable rotation.

On the other hand, when the idle operation is shifted to normal load operation, the status flag IF is set in step 109.
is set to "0", and in step 110,
An opening degree signal S corresponding to the operating state is calculated, and in step 108, the intake air amount regulating valve 2 is controlled to a predetermined opening degree.

Note that in the control unit 19, the steps
102 to 105 constitute the idle time integration means 6 according to the present invention, and step 106 constitutes the target value setting means 7. Of course, each of these means can also be constructed using hard circuit means.

In the above embodiment, a case has been described in which the intake air amount adjustment valve 2 provided in the bypass air passage 18 is controlled, but the intake air amount is adjusted by controlling the opening degree of the throttle valve 16. It's okay.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of the present invention, Fig. 2 is a system configuration diagram according to an embodiment of the invention, Fig. 3 is a flowchart of idle rotation control, and Fig. 4 is a determination of the target value Trpm of idle rotation. It is a graph showing an example of a function. 1...Engine, 2...Intake air amount adjustment valve, 5
... Control means, 6 ... Idle time accumulation means, 7
...Target value setting means.

Claims (1)

[Scope of Claims] 1. An intake air amount adjustment valve that adjusts the amount of intake air supplied to the engine, and a control means that controls the intake air amount adjustment valve so that the engine speed during idling reaches a target value. An idle speed control device for an engine, comprising: idle time integrating means for integrating the time elapsed since idling; and a signal input from the idle time integrating means, when the integrated time is large compared to when it is small. An engine idle rotation control device comprising target value setting means for setting the target value high.