JPH0422731A - Idling speed controller of internal combustion engine for vehicle - 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 <Industrial Application Field> The present invention relates to an idle speed control device for a vehicle internal combustion engine.

<Prior art> As an idle speed control device for a vehicle internal combustion engine, an auxiliary air control valve is provided in an auxiliary air passage that bypasses a throttle valve, and the actual engine speed and target idle speed are compared under idling operating conditions. There is a system in which the opening degree of the auxiliary air control valve is controlled based on the comparison result to perform feed-hack control of the engine speed to the target idle speed (see Japanese Patent Laid-Open No. 118542/1983).

(Problems to be Solved by the Invention) Incidentally, in such an idle speed control device, it is desirable to set the target idle speed low in order to improve fuel efficiency.

However, the feedback control has a poor ability to follow disturbances such as sudden deceleration from a high-speed range, and may stall, so there is a problem in that the target idle rotation speed must be set to a certain degree high.

SUMMARY OF THE INVENTION In view of these conventional problems, it is an object of the present invention to stabilize control during sudden deceleration from a high speed range and to set a target idle rotation speed low.

<Means for Solving the Problems> Therefore, as shown in FIG. An internal combustion engine for a vehicle, comprising means (feedback control means) for controlling the opening of an auxiliary air control valve based on the comparison result to feed bank control the engine speed to the target idle speed. In the idle speed control device of (model setting means); means (comparison means) for comparing the opening degree of the auxiliary air control valve under the feedback control with the opening degree according to the reference model and emitting a signal when the difference is large; This configuration includes means (feedforward control means) for stopping the control and for feedforward controlling the opening degree of the auxiliary air control valve according to a reference model.

Effect〉 In the above configuration, when starting from high speed range and decelerating,
Feedback control with poor followability is stopped, and feedforward control is performed according to the time-auxiliary air control valve opening characteristic based on a predetermined reference model to improve engine stall resistance. This makes it possible to lower the target idle rotation speed.

<Example> An embodiment of the present invention will be described below.

In FIG. 2, air from the air cleaner 1 passes through an intake duct 2 and is inserted into a throttle valve 3 that is linked to an accelerator pedal (not shown) and an auxiliary air passage 4 that bypasses the throttle valve 3! The air is inhaled under the control of the auxiliary air control valve 5. And intake manifold 6
The mixed fuel is mixed with the fuel injected from the fuel injection valve 7 and sucked into the engine 8.

The opening degree of the auxiliary air control valve 5 is controlled by a control signal from a control unit 9, and for this control, signals from various sensors are input to the control unit 9.

As the various sensors described above, a rotation speed sensor 10 is provided to detect the engine rotation speed N. Further, a water temperature sensor 11 is provided to detect the engine cooling water temperature Tw. Further, a throttle sensor 12 is provided to detect the throttle valve opening TVO. Further, a vehicle speed sensor 13 is provided, and the vehicle speed VS
Detect P. In addition, a neutral switch 14 that is turned on when the transmission is in the neutral position.
A brake switch 15, etc., which is turned on when the brake pedal is depressed, is provided.

Here, the microcomputer in the control unit 9 performs arithmetic processing according to the flowchart in FIG. 3 based on the signals from the various sensors, and controls the opening degree of the auxiliary air control valve 5.

The routine shown in FIG. 3 is executed at predetermined time intervals.

In step 1 (denoted as Sl in the figure; the same applies hereinafter), a basic control value 15Ct-(%) is set by searching a map based on the water temperature TW detected by the water temperature sensor 11.

In step 2, it is determined whether or not the idle operating condition (idle rotational speed feedback control condition) is met. Here, the idle speed feedback control condition is that the throttle valve is fully closed and in a neutral state, or that the throttle valve is fully closed and the vehicle speed is below a predetermined value.

In the case of idle rotation speed feedbank control conditions, feedback control is performed in steps 3 to 6. That is, in step 3, the target idle rotation speed Ns is searched by referring to a map based on the water temperature Tw, and in step 4, the engine rotation speed N detected by the rotation speed sensor 10 is compared with the target idle rotation speed Ns. , when N<Ns, Ste.
Feedback correction value 15CC is determined by integral control in block 5.
Increase L (%) by a predetermined integral I with respect to the previous value, and NU
When NS, in step 6, the feedback correction value l5Cet (%) is decreased by a predetermined integral I from the previous value by integral control.

Then, in step 7, the valve opening duty I SO,N (%) is calculated from the basic control value l5Cytv and the feedback correction value l5CCL according to the following equation.

I S CoN=I S Ctu+I S Cct Here, steps 1 to 7 correspond to the feedback control means.

In the next step 8, it is determined whether or not there is a sudden deceleration from a high speed range based on driving conditions such as vehicle speed VSP and brake condition. This portion corresponds to the rapid deceleration detection means.

In the case of No, the process directly proceeds to step 14 and outputs this valve opening duty rsco.

If YES (sudden deceleration), proceed to step 9.

In step 9, reference is made to a reference model in which the opening degree (valve opening duty) of the auxiliary air control valve during sudden deceleration is predetermined using time as a parameter, and the reference model is opened according to the elapsed time of - from the time when sudden deceleration is first detected. Search for valve duty l5CON'. This part corresponds to the norm model setting means.

In step 10, the standard valve opening duty ISC.

and the valve opening duty l5 by the feed pump control.
Difference from CON Δl5C=ISCON' l5CON
In the next step 11, the difference ΔISC is compared with a predetermined value C, and when ΔISC≧C (when the difference is large), the process proceeds to step 12. These parts correspond to comparison means.

In step 12, the standard valve opening duty l5Cos is set as the valve opening duty ISC, , and the process proceeds to step 14.
This valve opening duty I S C0N= T S CON
Output. That is, feedback control is stopped and feedforward control is performed according to the reference model. This part corresponds to the feedforward control means.

In addition, for conditions other than the idle rotation speed feedback control condition, proceed from step 2 to step 13, and set the valve opening duty I.
S C0N=I S CTw+I S Cct is calculated and output in step 14, but at this time, the clamped ISC is used.

When the valve opening duty ISC,, is output in step 14, the valve opening coil of the auxiliary air control valve 5 is energized by the pulse signal of this valve opening duty 15COH, thereby controlling the opening degree and providing the desired auxiliary air control valve. Air flow rate is obtained.

According to such control, the following effects can be obtained compared to the conventional method.

Referring to FIG. 4, when there is a sudden deceleration from a high speed range and the idle rotation speed feedback control conditions are met, according to the conventional feedback control, the opening of the auxiliary air control valve (IS
There was a risk that the engine stall (O opening) would suddenly decrease as shown by the solid line in the figure and undershoot, leading to engine stall, but in the case of the present invention, feedforward control is performed according to the standard model as shown by the broken line in the figure. This improves engine stall resistance.

<Effects of the Invention> As explained above, according to the present invention, feedback control is stopped during sudden deceleration and feedforward control is performed according to the standard model, which improves engine stall resistance and lowers the target idle speed. It is possible to achieve the effect of improving fuel efficiency.

[Brief explanation of the drawing]

Fig. 1 is a functional block diagram showing the configuration of the present invention, Fig. 2 is a system diagram showing an embodiment of the invention, Fig. 3 is a flowchart showing control contents, and Fig. 4 is a diagram showing control characteristics. . 3... Throttle valve 4... Auxiliary air passage 5
... Auxiliary air control valve 8 ... Engine 9 ... Control unit 10 ... Rotation speed sensor 11.
...Water temperature sensor 12...Throttle sensor 1
3...Vehicle speed sensor

Claims (1)

[Claims] An auxiliary air control valve is provided in the auxiliary air passage that bypasses the throttle valve, and the opening degree of the auxiliary air control valve is controlled based on the comparison result by comparing the actual engine speed and the target idle speed under idling operating conditions. An idle speed control device for an internal combustion engine for a vehicle, which includes means for feedback controlling the engine speed to a target idle speed based on the running state of the vehicle, and means for detecting sudden deceleration based on the running state of the vehicle, means for setting a reference model of the opening of the control valve; means for comparing the opening of the auxiliary air control valve according to the feedback control with the opening according to the reference model and generating a signal when the difference is large; An idle rotation speed control device for an internal combustion engine for a vehicle, characterized in that the idle speed control device for an internal combustion engine for a vehicle is provided with means for stopping the feedback control in response to the feedback control and feedforward controlling the opening degree of the auxiliary air control valve according to a reference model.