Method and apparatus for controlling engine idling speed

• US 4,344,399 A
• Filed: 09/12/1980
• Issued: 08/17/1982
• Est. Priority Date: 09/14/1979
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Matsumura, Toshimi, Yamazoe, Hisamitsu, Omori, Norio
• Primary Examiner(s): Argenbright, Tony M.
• Application Number:
  US06/186,449
• Time in Patent Office: 704 Days
• Field of Search: 123/339, 123/352, 123/585, 364/431
• US Class Current: 477/111
• CPC Class Codes: F02D 41/26 using computer, e.g. microprocessor
• CPC Class Codes: F02D 43/00 Conjoint electrical control of two or more functions, e.g. ignition, fuel-air mixture, recirculation, supercharging or exhaust-gas treatment
• 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

To control the idling speed of an automotive engine, a control amount is predetermined which determines an idle air flow for providing a basic idling speed and the idle air flow is adjusted in accordance with the control amount. Also, when the engine is idling after the completion of the warm-up operation, in accordance with the difference between a predetermined desired engine idling speed and the actual engine speed attained after the adjustment of the idle air flow in accordance with a basic control amount, a correction value for compensating the basic control amount is computed and memorized such that the actual engine idling speed is adjusted to the desired speed, whereby the idle air flow is adjusted in accordance with the memorized correction value and the basic control amount in all the engine operating conditions including the idling operation.

Claims

1. In a method of controlling the idling speed of a throttle valve equipped engine of an automobile having an air conditioner system and a transmission, including the steps of preliminarily establishing a control amount which determines an idle air flow for providing a basic idling speed and adjusting said idle air flow in accordance with said control amount, the improvement comprising the steps of:

computing said control amount from a basic control amount and a variable correction value being maintained to a constant value during the warm-up of the engine;

computing a difference value between a target idle speed and an actual idle speed of the engine, computing the correction value from the difference value so that the actual idle speed is adjusted to the target idle speed, memorizing the computed correction value and computing the control amount from the memorized correction value and the basic control amount after the termination of warm-up of the engine; and

adjusting said idle air flow in accordance with said memorized correction value and said basic control amount under all the operating conditions of said engine including the idling operation thereof.

2. A method according to claim 1, wherein said memorizing step comprises:

sensing a warm-up operating condition of said engine;

sensing a position of said throttle valve upon completion of said warm-up operation;

sensing a vehicle speed of said automobile when said throttle valve is in a full-closed position thereof;

sensing a rotational speed of said engine when said vehicle speed is zero; and

sensing a variation in the speed of said engine when said engine has a rotational speed.

3. A method according to claim 2, further comprising the steps of:

sensing an operation of said air conditioner system when said engine speed variation is small;

sensing a position of said transmission when said air conditioner system is not in operation; and

computing and memorizing a correction value when said transmission is in a neutral position thereof.

4. A method according to claim 1 which further comprises the steps of discriminating whether said correction value is correct or not, and returning said correction value to an initial value when said correction value is not correct.

5. A method according to claim 1 which further comprises the steps of discriminating whether a starter starting the engine is on or off, and adding a preset value to said control amount when the starter is on.

6. A method according to claim 1 which further comprises the steps of detecting the temperature of the engine, and varying said control amount in accordance with the detected temperature of the engine.

7. In an apparatus for controlling the idling speed of an engine having speed sensor means for sensing a rotational speed of said engine, temperature sensor means for sensing a temperature of said engine, electronic control means responsive at least to output signals of said speed sensor means and said temperature sensor means to generate a control amount signal for controlling an idle air flow to said engine, and air control valve means responsive to said control amount signal from said control means so as to control said idle air flow, the improvement wherein said control means includes:

digital input port means for receiving the output signal of said speed sensor means;

analog input port means for receiving the output signal of said temperature sensor means;

microprocessor means responsive to output information of said digital input port means and said analog input port means for computing a control amount which consists of a basic control amount and a correction value;

memory means for storing said control amount computed by said microprocessor means and supplying desired information to said microprocessor, said basic control amount being preset into said memory means when, in accordance with the output signal of said temperature sensor means, it is determined that said engine is at a warm-up operation, and said correction value being stored in said memory means when the engine has warmed up completely, and rewritten in accordance with the difference value between a target value and the actual rotational speed of the engine; and

means for converting a digital output of said microprocessor relating to said idle air flow to operate said air control valve means.

8. An apparatus according to claim 7, wherein said memory means includes a nonvolatile memory backed up by a power supply for storing said correction value, a read only memory for storing a program, and a read/write memory for temporarily data while the program is being executed.