JPH01310143A - Idle rotational frequency controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To permit smoothly idle rotational frequency to rise immediately after the completion of cranking by feed-back controlling the opening control amount of an idle controlling valve after control by post-start opening control amount so that the idle rotational frequency approaches a desired rotational frequency. CONSTITUTION:In cranking detected by a cranking detecting means A, an idle controlling valve E is held to a certain opening controlling amount determined by water temperature or the like, by a cranking opening control amount setting means B. After the completion of the cranking, a post-start opening control amount setting means C sets the opening control amount of said valve E gradually reduced for at least a predetermined time after cranking. After completion of the control, a feed-back control means D controls the opening control amount of the idle controlling valve so that the idle rotational frequency approaches a desired rotational frequency. Thus, the idle rotational frequency after starting is adapted to rise smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a device for controlling the idle speed of an internal combustion engine, and particularly to a device that improves the control performance of the idle speed immediately after starting.

<Prior art> In an internal combustion engine equipped with an electronically controlled fuel injection device, the idle speed is controlled by duty-controlling the opening degree of an electromagnetic idle control valve installed in a passage that bypasses the intake throttle valve. is controlled.

During cranking, the idle control valve is maintained at a constant opening control value set based on water temperature, etc., but after cranking, that is, after starting, conventionally feedback control is performed to bring the idle rotation speed closer to the target rotation speed. It is common to do so.

<Problems to be Solved by the Invention> By the way, in the feedback control, the opening control value is usually set by proportional integral control, etc., but it is necessary to ensure responsiveness (proportional integral control value given immediately after cranking is completed). There is a system in which the bone l5CPIF is variably set according to the deviation ΔN between the target rotational speed and the actual rotational speed at the end of cranking as shown in the following equation.

l5CFIF=ΔN/N, ・K0 However, No is the standard deviation rotation speed, for example 50 rpm
, Ko are constants set including calculation correction by the microcomputer.

However, with this control method that variably sets the proportional bone l5CFIIF, it is difficult to turn off the starter switch before the cranking speed has risen sufficiently, such as at extremely low temperatures.
If cranking is ended as FF, the actual rotation speed will be significantly lower than the target rotation speed when feedback control is subsequently started, so the proportional bone ISC □ set by the above formula will be considerably If the value becomes large, as shown in FIG. 5, a problem arises in that the rotation speed increases and the feeling deteriorates.

The present invention was made in view of these conventional problems, and an object of the present invention is to provide an idle speed control device for an internal combustion engine that can smoothly start up the idle speed immediately after cranking is completed. do.

Means for Solving the Problems> For this reason, the present invention, as shown in FIG. In the idle speed control device for an internal combustion engine, a cranking detection means detects cranking, a cranking opening control amount setting means sets an opening control amount of an idle control valve during cranking, post-start opening control amount setting means for setting an opening control amount of the idle control valve after cranking is gradually decreased from the opening control amount during cranking by at least a predetermined time; The configuration includes a feedback opening control amount setting means for feedback controlling the opening control amount of the idle control valve after the control so that the idle rotation speed approaches the target rotation speed.

<Operation> During cranking, which is detected by the cranking detection means, the cranking opening control amount setting means maintains the idle control valve at a constant opening control amount set by the water temperature or the like.

When cranking is completed, the post-start opening control amount setting means sets the opening control amount of the idle control valve to be gradually decreased by at least a predetermined period of time from the opening control amount during cranking.

After the control by the post-start opening control amount setting means is completed, the opening control amount of the idle control valve is feedback-controlled by the feedback control means so as to bring the idle rotation speed closer to the target rotation speed.

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

In FIG. 2 showing the configuration of one embodiment, an idle control valve 5 is interposed in an auxiliary air passage 4 that bypass-connects the upstream and downstream sides of an intake throttle valve 3 installed in an intake passage 2 of an engine 1. The idle speed is controlled by controlling the opening degree of the idle control valve 5 according to the operating state of the engine.

Opening control of the idle control valve 5? The Il amount is a signal from the idle switch 6 that is ON when the intake throttle valve 3 is in the idle position and OFF otherwise, the cooling water temperature detected by the water temperature sensor 7, the engine speed detected by the crank angle sensor 8, and the start switch. ON, O from 9
Control unit 10 based on signals such as FF signals
determines the engine operating state, and determines the valve opening duty of the pulse signal supplied to the idle control valve 5 according to this operating state (the percentage of ON time in the pulse cycle, on the opening side?11
11) as described below.

In addition, on the upstream side of the intake throttle valve 3 in the intake passage 2,
An air flow meter 11 is provided to detect the intake air flow rate, and an air cleaner 12 is further provided upstream of the air flow meter 11.

Idle rotation speed control by the control unit 10 will be explained below with reference to the flowchart of FIG. 3.

In step 1 (denoted as S in the figure), it is determined whether or not cranking is in progress by determining whether the start switch 8 is ON or OFF. That is, the start switch 8 and the function of step 1 constitute cranking detection means.

When it is determined in step 1 that the start switch 8 is ON, that is, cranking is in progress, the process proceeds to step 2, and the idle control valve 5 is opened during cranking based on the cooling water temperature detected by the water temperature sensor 7. Valve duty IS
Set C to 4filSCsr retrieved from a map stored in ROM or calculated. That is, the function of step 2 corresponds to the cranking opening side '4H amount setting means.

On the other hand, when it is determined that the start switch 8 is OFF in step 1, the process proceeds to step 3, where a timer is counted up, and then the process proceeds to step 4, where the elapsed time T after the end of cranking is set from the count value of the timer. value T0
Determine whether it has been reached.

Then, until the set value T0 is reached as determined in step 4, the process proceeds to step 5, and the valve opening duty l5CAs of the idle control valve 5 is calculated and set using the following equation. That is,
The function of step 5 corresponds to a post-start opening control amount setting means.

l5C=ISCas. -T・ΔIS Here, l5CAso is the initial value set based on water temperature, etc., and ΔISC is, for example, the setting cycle of this routine (LoII
This is the valve opening duty ISC that is decreased every time Is), so that the valve opening duty ISC is set to gradually decrease from the initial value 15CAso for at least a predetermined time T0 after the end of cranking.

Next, in step 4, the set time T after cranking is completed. If it is determined that the vehicle speed has passed, the process proceeds to step 6, where it is determined whether or not the feedback control condition of the vehicle speed being less than or equal to a set value is satisfied.

When it is determined that the feedback control condition is not satisfied, the process returns to step 5 and continues control to gradually reduce the valve opening duty.

On the other hand, when it is determined that the feedback control is satisfied, the process proceeds to step 7 and subsequent steps, and feedback control is started to bring the idle rotation speed closer to the target rotation speed.

First, in step 7, the target rotational speed NA is set by searching from a map or the like based on the water temperature and the like.

Next, in step 8, the engine speed N detected by cranking 8 is compared with the set target speed NA.

If it is determined that NA>N, the process proceeds to step 9, where the ISC of the valve opening duty at the idle speed is gradually increased and set using the following formula.

rsc=Isc+Δl5CF[l Furthermore, when it is determined that NA<N, the process advances to step IO and similarly the feedback control value rsc is calculated.

Set by gradually decreasing.

l5CISC-Δl5Cra Note that when it is determined that NA=N, the current state is maintained.

In this way, after setting the valve opening duties I and SC of the idle control valve 5 according to the operating state, step 1
1, a pulse signal having the set valve opening duty ISO is output to the idle control valve 5, whereby the idle control valve 5 is controlled to a predetermined opening degree.

If such control is performed, the opening degree of the idle control valve 5 will be small after cranking (feedforward control is performed to gradually decrease for a predetermined period of time, and then feedback control will be started, so that the rotation increase after starting will be reduced). As shown in FIG. 4, it becomes smooth, and the speed rise due to feedback control immediately after cranking to extremely low temperatures, which is the case with the conventional method, can be prevented, and the starting feeling is improved.

<Effects of the Invention> As explained above, according to the present invention, the increase in the engine speed after startup becomes clear and the feeling is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 3 is a flowchart showing an idle rotation speed control routine according to the above embodiment.
FIG. 4 is a time chart showing the control state during the same control as above, and FIG. 5 is a time chart showing the control state during the conventional control. 1... Engine 2... Intake passage 3... Intake throttle valve 4... Auxiliary air passage 5... Idle control valve 6... Idle switch 8...
Crank angle sensor 9...Start switch 1
0... Control unit patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima

Claims (1)

[Claims] A cranking detection means for detecting cranking in an idle rotation speed control device for an internal combustion engine that controls the idle rotation speed by controlling the opening degree of an idle control valve installed in a passage that bypasses an intake throttle valve. and cranking opening control amount setting means for setting the opening control amount of the idle control valve during cranking, and a cranking opening control amount setting means for setting the opening control amount of the idle control valve after cranking. a post-start opening control amount setting means that gradually decreases the post-start opening control amount for at least a predetermined period of time; 1. An idle rotation speed control device for an internal combustion engine, comprising: feedback opening control amount setting means for performing feedback control.