Engine idling speed control method and apparatus

• US 4,444,168 A
• Filed: 01/27/1982
• Issued: 04/24/1984
• Est. Priority Date: 01/29/1981
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Omori, Norio, Matsumura, Toshimi
• Primary Examiner(s): Nelli, Raymond A.
• Application Number:
  US06/343,366
• Time in Patent Office: 818 Days
• Field of Search: 123/339, 123/340, 123/179 B, 123/179 G
• US Class Current: 477/111
• CPC Class Codes: F02M 69/32 with an air by-pass around the air throttle valve or with an auxiliary air passage, e.g. with a variably controlled valve therein

Abstract

An engine speed control method and apparatus employs at least two basic control variable maps comprising a first basic control variable map for determining the desired air flow to an internal combustion engine in accordance with the warming conditions of the engine during the starting period and a second basic control variable map for determining the desired air flow in accordance with the warming conditions of the engine after the starting period, and the maps are used selectively in accordance with the warming conditions of the engine. Upon change-over from the control according to one map to the control according to the other map, the air flow is varied gradually at intervals of predetermined engine revolutions or a predetermined period of time so as to effect the change-over to the control according to the desired map. During the idling operation after the engine has been warmed up sufficiently, the difference between each of the desired idling speeds preliminarily established in correspondence to the operating conditions of the engine and the actual idling speed is detected and the required correction values of the basic control variable for controlling the air flow are computed and stored thereby controlling the idling speed of the engine.

Claims

1. In a method of controlling an idling speed of an internal combustion engine in accordance with a basic control variable preliminary established for controlling an idle air flow so as to maintain the idling speed at a rate corresponding to a warming condition of the engine, the improvement including:

selectively using at least two different supply sources for supplying said basic control variable in accordance with engine conditions and load conditions of said engine,

wherein said supply sources include at least a first basic control variable supply source for engine starting purposes and a second basic control variable supply source for warming up purposes, and

wherein upon change-over between said sources, said control variable obtained in accordance with said first source is decreased by a predetermined value every predetermined interval such that when said control variable becomes smaller than one obtained in accordance with said second source, said control variable is varied in accordance with said second source.

2. A method according to claim 1, wherein said decrease by a predetermined value is made at intervals of a predetermined time period.

3. A method according to claim 1, wherein said supply sources include at least a first basic control variable supply calculation formula for engine starting purposes and a second basic control variable supply calculation formula for warming up purposes.

4. A method according to claim 1, wherein during an idling operation after said engine has warmed up sufficiently, in accordance with the differences between desired idling speeds preliminarily established in correspondence to operating conditions of said engine and the actual idling speeds thereof correction values of said basic control variable which are required to reduce the differences between said actual idling speeds and said desired idling speeds to zero are computed and stored, whereby under all the operating conditions of said engine including said idling operation said basic control variable supplied in accordance with said supply sources is corrected in accordance with said correction values (R) so as to adjust said idle air flow.

5. An engine idling speed control apparatus for an automobile having an air-conditioner, comprising:

sensor means, including a starter operation sensor, automatic-transmission operation sensor, engine warm-up-sensor and air-conditioner operation sensor, for generating signals indicating engine operating conditions;

electronic control means, responsive to said signals, for generating a first signal to instruct an amount of injected fuel and generating a second signal to instruct an amount of correcting air-flow to the engine; and

means for controlling the amount of injected fuel according to the first signal and means for controlling the amount of air-flow to the engine according to the second signal;

wherein said electronic ciontrol means includes at least two kinds of function means each defining the second signal variable as each predetermined function of change of at least one of said sensor generating signals, and

wherein said electronic control means includes a central processor unit for calculating out the first and second signals in response to said sensor generating signals, first source means defining the second signal for engine starting condition, second source means defining the second signal for engine warming-up condition, and means for discriminating engine starting and warming-up conditions from said sensor signals to select the corresponding one of said source means.

6. An apparatus according to claim 5, wherein said electronic control means includes first storage means for storing a correction value of the second signal predetermined in correspondence with signals generated by the automatic-transmission operation sensor and air-conditioner operation sensor which represent an engine load condition, a second storage means for storing a desired idling speed indicating value in corresponding to an engine load condition, means for modifying the correction value to reduce difference between the desired idling speed and actual idling speed sensed by said speed sensor, and means for updating the corresponding second signal by the modified correction value.