Vehicle engine idle speed governor with unsymmetric correction rates

• US 4,245,599 A
• Filed: 12/19/1979
• Issued: 01/20/1981
• Est. Priority Date: 12/19/1979
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Des Lauriers, Edwin D.
• Primary Examiner(s): Myhre, Charles J.
• Assistant Examiner(s): Nelli, Raymond A.
• Application Number:
  US06/105,371
• Time in Patent Office: 398 Days
• Field of Search: 123/102, 123/119 F, 180/105 E, 60/39.28 R, 60/39.28 P, 60/39.28 T, 328/69
• US Class Current: 123/353
• CPC Class Codes: F02D 31/004 by controlling a throttle stop
• CPC Class Codes: F02M 3/07 by positioning the throttle flap stop, or by changing the fuel flow cross-sectional area, by electrical, electromechanical or electropneumatic means, according to engine speed

Abstract

A vehicle engine has a throttle stop positionable in response to an actuator command signal to determine engine idle speed. Apparatus is provided to generate a speed error signal having both an absolute value and a further characteristic indicative of high or low speed; and further apparatus is provided including a memory effective to store actuator command signals corresponding to specific speed error signals and speed correction apparatus effective to obtain an actuator command signal from the memory corresponding to each speed error signal and supply the actuator command signal to the throttle stop positioning apparatus to correct engine idle speed in the direction of a predetermined desired engine idle speed. The actuator command signals corresponding to at least the largest low speed error signals have absolute values effective to produce a greater throttle stop movement than the actuator command signals corresponding to the high speed error signals of the same absolute value, so that the control responds at a faster rate to large low speed errors than to equivalently large high speed errors.

Claims

1. In a vehicle engine having fuel induction and control means including a throttle for controlling the air flow rate to the engine and a throttle stop for determining the engine idle throttle position, engine idle speed governing apparatus comprising:

actuator means effective to position the throttle stop in response to an actuator command signal, said actuator means being capable of movement, at least in the direction of decreasing engine speed, at a faster rate than the engine itself can decrease its speed;

means effective to generate a speed error signal having an absolute value proportional to the difference between engine speed and a predetermined reference and a further characteristic indicative of high or low speed, respectively, for speeds greater than the reference or speeds less than the reference;

memory means effective to store predetermined actuator command signals corresponding to individual high and low speed error signals, the actuator command signals corresponding to at least the largest low speed error signals having values effective to produce a greater throttle stop movement than the actuator command signals corresponding to the high speed error signals of the same absolute value;

means effective to obtain from the memory means the actuator command signal corresponding to the speed error signal and to provide the actuator command signal to the actuator means to generate a throttle stop movement to return engine idle speed toward the reference by an amount determined at least in part by the value of the actuator command signal, whereby at least large corrective throttle stop movement is smaller in the correction of high engine idle speed than in the correction of low engine idle speed to prevent excessive overshoot while decreasing engine speed with the consequent possibility of engine stall.

2. In a vehicle engine having fuel induction and control means including valve means effective to control the flow of air to the engine, engine idle speed governing apparatus comprising:

actuator means effective to position the valve means in response to an actuator command signal;

means effective to generate a speed error signal having an absolute value proportional to the difference between engine speed and a predetermined reference and a further characteristic indicative of high or low speed, respectively, for speeds greater or less than the reference;

memory means effective to store predetermined actuator command signals corresponding to individual high and low speed error signals, the actuator command signals corresponding to at least the largest low speed error signals having values effective to produce a greater movement of the valve means than the actuator command signals corresponding to the high speed error signals of the same absolute value; and

means effective to obtain from the memory means the actuator command signal corresponding to the speed error signal and to provide the actuator command signal to the actuator means to generate a movement of the valve means to return engine idle speed toward the reference by an amount determined at least in part by the value of the actuator command signal, whereby at least large corrective movements of the valve means are smaller in the correction of high engine idle speed than in the correction of low engine idle speed to reduce the tendency of engine stall during idle.

3. An idle speed control system for an internal combustion engine for maintaining its idle speed at a predetermined value comprising:

movable air flow control means for varying the flow of air into the engine and thereby its output speed;

an electrical bidirectional actuator coupled to said air flow control means for moving it in opposite directions to thereby control the amount of air flow to the engine, said actuator moving said movable means by amounts corresponding to the duration of electrical energization of the actuator;

means for sensing engine speed;

means providing a reference signal indicative of a desired engine speed;

means for developing an error signal which is a function of the deviation of actual engine speed from desired engine speed;

electrical pulse generator means responsive to the magnitude of said deviation to provide output electrical energizing pulses to said actuator wherein the durations of said pulses are a function of the magnitude of the deviation and wherein greater durations are provided for a given speed deviation, at least for large deviations, when the engine is operating below said reference speed; and

,

means responsive to the sense of said error signal for controlling the direction of movement of said air flow control means such as to move said air flow control means in a direction to increase the flow of air into the engine when engine speed is below said reference speed and to move the air flow control means in an opposite direction to thereby reduce air flow to the engine when engine speed is above said reference value.