JPS60212647A - Engine-speed control for internal-combustion engine - Google Patents

Abstract

PURPOSE:To previously prevent engine stall by adding the increased portion to the opening degree of an idle speed control valve installed into a passage making a detour around a throttle valve, during the time when the engine speed is high and an idle switch is in opened state when the throttle valve is sharply closed. CONSTITUTION:During the operation of an engine, a CPU32 in a control unit 30 reads the opening degree TAi of a throttle valve 24 at present at a certain cycle from the output signal of a detecting means for detecting the opening degree of the throttle valve 24, and the difference DELTATA from the opening degree TAi-1 in the preceding time is obtained. Then, it is checked from DELTATA that the throttle valve 24 is in closing procedure or not, and in case of closing, DELTATA is compared with a set value L1. If DELTATA>L1, the engine speed NE obtained by a tachometer 38 is compared with a set value L2, and if NE>L2, an idle speed control valve 28 in a bypass passage 26 is opened by a prescribed amount with an idle switch LL in OFF-state, and engine stall is prevented beforehand.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for controlling the rotational speed of an internal combustion engine, and the present invention relates to a method for controlling the rotational speed of an internal combustion engine. The aim is to make it executable.

Prior Art and Problems When the throttle valve is rapidly closed during no-load operation of an automobile engine (internal combustion engine), the engine speed decreases rapidly.
There is a risk of engine stalling if the non-negative rotational speed is lowered. Engine idle speed is fuel efficiency 1i -
It is desirable to have it as low as possible from the viewpoint of
In order to have a throttle speed of 14, bypass 1L to the throttle valve.
There is a system in which an I/3 is provided, an I5C (idle speed 1-1-3-A) valve is provided in the Ill path, and the valve is controlled by a control device. The opening degree of the TSC valve is set to obtain the desired low idle speed. During no-load operation, the throttle valve is opened by depressing the accelerator pedal (racing condition), and then the throttle valve is opened by releasing the accelerator pedal. If the engine is fully closed (there is a slight gap), the idle speed will not be maintained due to inertia and there is a risk of the engine stalling.

OBJECTS OF THE INVENTION The present invention addresses these problems and attempts to prevent the engine from stalling even if the throttle valve is rapidly closed during no-load operation.

Structure of the Invention The present invention provides a method for controlling the rotational speed of an internal combustion engine in which an idle speed control valve is provided in a passage that bypasses a throttle valve. The intake air amount of the internal combustion engine is increased by adding an increased amount to the opening of the control valve under the condition that the switch is open, and when the condition is no longer satisfied, the increased amount is removed by a predetermined amount. This will be explained next with reference to the drawings.

Embodiment of the Invention FIG. 1 shows an embodiment of the invention, in which 10 is an engine cylinder, 12 is a piston, 14 is an intake valve, 16 is an exhaust valve,
18 is a spark plug, 20 is an air supply pipe, 22 is an exhaust pipe, 24 is a throttle valve provided in the air supply pipe, 26 is a passage bypassing the valve portion, 28 is an ISO valve inserted in the passage,
30 is its control unit. Although not shown, a fuel supply port from a carburetor is provided before and after the throttle valve 24, or a fuel injection valve is installed. The control unit 30 has a processor (CPU) 32 and receives engine speed NE from a tachometer 38 via an input interface 34.
A signal indicating the throttle valve opening TA, a signal indicating the throttle valve opening TA from the throttle valve device, and an on/off signal of the throttle fully closed switch LL are taken in, the opening degree of the ISC valve 28 is calculated, and this is sent to the output interface 36 to the im system. and sends it to the ISC valve. If the signal does not indicate the throttle valve opening TA, it is output from a potentiometer or the like attached to the throttle valve. Also, if the throttle valve is equipped with an idle switch T, I-
is installed, and when the throttle valve is fully closed, the switch L
L is on, otherwise it is off. The control unit 30 determines the TSC valve opening degree as follows.

FIG. 2 shows changes in engine speed when the throttle valve is closed, with the horizontal axis representing time t and the vertical axis representing throttle valve opening and engine speed NE.

D+ is the throttle valve opening corresponding to the idle speed NE+, and D2 is Dl corresponding to the high rotation speed NE2 during racing.
This is a larger appropriate throttle valve opening. In this figure, D + , NE + , etc. are shown at the same position for convenience. When the throttle valve 24 is closed from D2 to Dl, the rotational speed decreases monotonically as shown by the curve NEa and reaches a new rotation speed NE.
In some cases, the pressure may settle to +, but as shown by curve NEb, an undershoot may occur and an engine stall may occur.

Examples of cases where the curve NEb occurs include when the idle speed NE+ is considerably low, when the valve is closed too violently, and so on. Generally, the engine speed changes later than the change in the throttle valve opening, but when the valve opening changes slowly, as shown by the curve Da in Figure 3, the engine speed changes according to the curve NE.
As shown by C, it follows Da well. However, if the valve opening is too large as shown by the curve Db, the engine speed will no longer follow <Db as shown by the curve NEd, resulting in undershoot.

If there is a risk of undershoot occurring, it is effective to open the ISC valve and increase the engine output. Although it has been considered to open the ISO valve by a predetermined amount by turning on and off the idle switch, this method cannot be said to correspond to the deceleration state of the engine. Furthermore, once the ISO valve is opened, it is desirable to release it immediately after preventing engine stall, otherwise deterioration of fuel efficiency will be inevitable.

In consideration of these points, in the present invention, ISC valve control is performed as shown in FIG.

- That is, the current throttle valve opening TAi at a certain period during operation.
Read it and calculate the difference ΔTA from 1゛A from last time and heat. Next, from this ΔTA, it is checked whether the throttle valve is being closed or opened, and whether it is being closed (
N), it is checked whether this ΔTA is larger than the set value 1. If it is large, there is a risk of engine stalling, and in this case, it is checked whether (N) engine speed NB is larger than the set value L2. If large (
N), this means that it is rapidly decelerating from high speed rotation,
There is a strong possibility that the engine will stall. Therefore, it is checked whether the idle switch LL is on or not, and if it is not on (N), the throttle valve is further tightened and there is a greater possibility of engine stalling, so the TSC valve is opened and closed in a predetermined manner. LD is the predetermined amount, and this is the increased amount LD of the ISC valve, and D
Let ++tD be the IsC valve opening degree. This completes the control this time, and tAl is set to tA, heat.

To explain this with reference to Figure 5, in this figure (al is the throttle valve opening TA, (bl is the on/off state of the idle switch LL, (cl is the engine speed NE, and ldl is each change in the valve opening of the ISC valve. The horizontal axis is time.

If the change ΔTA in the throttle valve opening TA is large, it is in the closing direction, the idle switch LL is still off, and the engine speed NE is high (in this diagram, these conditions are assumed to have been met at time t1). The ISO valve opening is D+ by adding tD to the normal valve opening at idle.
+tD.

Once the increased amount tD is added to the ISC valve opening degree, it is preferable to remove the increased amount tD as soon as possible without stopping the engine. This is done in stages by removing the attenuated bone ttD one by one when the release condition is met.

The release conditions are as shown in the figure: ΔTA is less than L + , 1 (Y), NP is less than 1, 2, and idle switch I, 1. are on.

When any of these conditions holds true, t from LD
Subtract tD and use it as the new LD. It is checked whether this is true or not, and if it is true, it is added to the tDt-D and D+tD is made new. If LD>Q is not (N), set tD to 0,
Control ends. In Fig. 5, it is assumed that Ll is turned on at time t2, and the release condition (Sh1) is established.If this is delayed and the time when Nfi becomes less than I-2 comes first, release will start from this time. .

When ΔTA is on the open side, that is, the throttle valve is opening (Y), the ATA is compared with the set values 1 and 3, and if ΔTA < L 3 is not established, that is, the throttle valve is opening rapidly. In this case, LD=o, and the ISO valve is not controlled.

When ΔTA<l, 3 (Y), this is also treated as one of the tD release conditions.

As described in detail, in the present invention, a predetermined amount is added to the TSC valve opening under the conditions that the throttle valve is rapidly closed, the idle switch is not closed, and the engine speed is still high, and this condition is satisfied. Since the predetermined amount is removed when the fuel runs out, engine stall can be avoided and the idle speed can be set low, which is extremely effective.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIGS. 2 and 3 are graphs explaining changes in engine speed, FIG. 4 is a flowchart showing the deceleration procedure of the present invention, and FIG. It is an operation explanatory diagram. In the drawing, 24 is a throttle valve, 26 is a bypass passage, and 28
is an idle speed control valve, LL is an idle switch, D is an opening degree of the control valve, tD is an increase amount, and 11D is a predetermined attenuation amount. Applicant Fujitsu Ten Ltd. Representative Patent Attorney Minoru Aoyagi No. 4 Figure 5 (b) LL OFF LLαN ((1) D. 1 l t2

Claims (1)

[Claims] In a method for controlling the rotational speed of an internal combustion engine in which an idle speed control valve is provided in a passage that bypasses a throttle valve, the throttle valve is rapidly closing, the rotational speed of the internal combustion engine is still high, and the idle switch is closed. The intake air amount of the internal combustion engine is increased by adding an increment to the opening of the control valve under the condition that the control valve is open, and when the condition is no longer satisfied, the increment is removed by a predetermined amount. A method for controlling the rotational speed of an internal combustion engine.