Idling speed control system of an internal combustion engine

Details Idling speed control system of an internal combustion engine Idling speed control system of an internal combustion engine

1984-12-07

1986-09-16

Cox, Ronald B.

Internal-combustion engines

Engine speed regulator

Idle speed control

290 40A, F02D 1110

Patent

active

046115609

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a system for controlling idling rotation speed of an internal combustion engine employed in an automobile or the like.


BACKGROUND ART

Some automobiles are equipped with an apparatus for controlling the idling rotation speed, by comparing the engine rotation speed under idling condition with a target idling rotation speed, changing the opening of a throttle valve depending upon the deviation therebetween so that the engine speed is controlled at a target rotation speed, thereby reducing the consumption of fuel under the idling condition.
Conventional apparatuses for controlling the idling speed use a cheaply constructed DC motor that works as an actuator to change the opening of the throttle valve, the DC motor being controlled in a rotating direction which corresponds to a speed deviation polarity between a target rotation speed and a practical rotation speed. To improve the control precision, furthermore, the DC motor is intermittently driven by intermittent feedback control pulses of a predetermined period, and the pulse width thereof is controlled depending upon the amount of the speed deviation. In this conventional apparatus, the pulse period is set so that the pulse pause interval hereinafter referred to as hold time becomes relatively long, by taking into consideration a snaking time of the DC motor and the delay time between the time when the opening of the throttle valve is changed and the time when the change of the engine speed is reflected thereby. Therefore, when it is expected that the engine rotation speed changes or drops abnormally due to the operation of loads such as an air-conditioning apparatus or a power steering appratus during a predetermined hold time, it is necessary to wait for the next pulse even when an estimated correction according to a pulse width correction is to be effected by detecting the operation of such loads. Accordingly, response for the change in the engine load is delayed possibly causing the engine to stall.


DISCLOSURE OF THE INVENTION

The present invention has been made in order to solve the above-mentioned problem, and its object is to provide an idling rotation speed control system of an internal combustion engine that exhibits a good response for changes in an engine load.
For this purpose, according to the present invention, provision is made of detection means to detect the operation condition of the engine load as operated under the idling condition or an abnormally low engine speed and a feedback control means to generate feedback control pulses of predetermined periods and holding time. The invention provides control means to generate control pulses responsive to abnormal changes in the operation condition or engine speed to change the opening of a throttle valve at a time independent of the generation of an ordinary feedback control pulse, and holding time.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram showing one embodiment of the present invention;
FIG. 2 is a block diagram illustrating the detailed structure of a control circuit;
FIG. 3 is a flow chart illustrating the operation contents of the control circuit;
FIG. 4 is a time chart illustrating a first embodiment of a pulse drive control step (113) of FIG. 3;
FIG. 5 is a graph showing one example of an actuation time of an actuator in relation to the deviation between a target engine speed and an engine speed;
FIG. 6 is a time chart showing one example of a control pulse that is generated when an air-conditioning apparatus starts to perate;
FIG. 7 is a flow chart illustrating a second embodiment of a pulse drive control step (113) corresponding to FIG. 4; and
FIG. 8 is a time chart showing a control pulse according to the second embodiment.


BEST MODES FOR PRACTICING THE INVENTION

FIG. 1 is a structural diagram illustrating one embodiment of the present invention. In this figure, the structure of the engine will be described first. Reference numeral (1) denotes a piston, (2) denotes a cylinder, (3) denotes an intake val

REFERENCES:
patent: 4184083 (1980-01-01), Takeuchi
patent: 4395985 (1983-08-01), Hagen
patent: 4441471 (1984-04-01), Krah
patent: 4467761 (1984-08-01), Hasegawa
patent: 4491108 (1985-01-01), Hasegawa

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