Idle speed control system for internal combustion engine

• US 6,006,723 A
• Filed: 07/21/1997
• Issued: 12/28/1999
• Est. Priority Date: 07/22/1996
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Deguchi, Yoshitaka, Takahashi, Nobutaka, Akabori, Kouichi
• Primary Examiner(s): Dolinar, Andrew M.
• Assistant Examiner(s): GIMIE, MAHMOUD
• Application Number:
  US08/897,824
• Time in Patent Office: 890 Days
• Field of Search: 123/339.12, 123/339.16, 123/339.17, 123/339.18, 123/339.23
• US Class Current: 123/339.17
• CPC Class Codes: F02D 31/005 by controlling a throttle by-pass
• CPC Class Codes: F02D 41/083 taking into account engine load variation, e.g. air-conditionning

Abstract

When an operation causing a decrease of the engine load is requested, for example, by switching off an air conditioner switch, an idle speed control system calculates a fuel decrease quantity from an engine load decrease quantity, and further calculates an air decrease quantity in accordance with a desired air fuel ratio after the engine load decrease, and the fuel decrease quantity. The control system decreases the air supply quantity to the engine by the air decrease quantity. Then, after the elapse of a preset time interval, the system controls the external load such as the air conditioner so as to reduce the engine load (for example, by turning off the air conditioner), and decrease the fuel injection quantity by the fuel decrease quantity. When the air conditioner is switched on, for example, the control system calculates a fuel increase quantity from the engine load increase, and further calculates an air increase quantity in accordance with the fuel increase quantity and a desired air fuel ratio after the engine load increase. Then, the control system controls the external load to increase the engine load, increases the fuel injection quantity and increases the air supply quantity.

Claims

1. An idle speed control system for controlling an idle speed of an internal combustion engine, the control system comprising:

load decreasing operation request detecting means for detecting a load decreasing operation request for an operation causing a decrease of a load on the engine;

desired air/fuel ratio setting means for setting a desired air/fuel ratio of an air fuel mixture supplied to the engine in accordance with an engine operating condition;

fuel decrease quantity calculating means for calculating a fuel decrease quantity for decreasing a fuel injection quantity in case of detection of the load decreasing operation request;

air decrease quantity calculating means for calculating an air decrease quantity for decreasing an air supply quantity in accordance with the desired air fuel ratio and the fuel decrease quantity in case of detection of the load decreasing operation request;

air supply quantity correcting means for decreasing the air supply quantity in accordance with the air decrease quantity in case of detection of the load decreasing operation request;

load controlling means for decreasing the load on the engine at an end of a preset time interval from detection of the load decreasing operation request; and

fuel supply quantity correcting means for decreasing the fuel injection quantity in accordance with the fuel decrease quantity at an end of a preset time interval from detection of the load decreasing operation request,

the load controlling means and the fuel quantity correcting means being timed so that there is a time difference between a load decreasing operation of the load controlling means and a fuel decreasing operation of the fuel supply quantity correcting means, to cause an actual decrease of a load torque applied on the engine and an actual decrease of an output torque of the engine to coincide with each other.

2. An idle speed control system for controlling an idle speed of an internal combustion engine, the control system comprising:

load decreasing operation request detecting means for detecting a load decreasing operation request for an operation causing a decrease of a load on the engine;

desired air/fuel ratio setting means for setting a desired air/fuel ratio of an air fuel mixture supplied to the engine in accordance with an engine operating condition;

fuel decrease quantity calculating means for calculating a fuel decrease quantity for decreasing a fuel injection quantity in case of detection of the load decreasing operation request;

air decrease quantity calculating means for calculating an air decrease quantity for decreasing an air supply quantity in accordance with the desired air fuel ratio and the fuel decrease quantity in case of detection of the load decreasing operation request;

air supply quantity correcting means for decreasing the air supply quantity in accordance with the air decrease quantity in case of detection of the load decreasing operation request;

load controlling means for decreasing the load on the engine at an end of a preset time interval from detection of the load decreasing operation request; and

fuel supply quantity correcting means for decreasing the fuel injection quantity in accordance with the fuel decrease quantity at an end of a preset time interval from detection of the load decreasing operation request,

the desired air/fuel ratio setting means including means for determining a desired air/fuel ratio after the decrease of the load,

the fuel decrease quantity calculating means including means for calculating the fuel decrease quantity corresponding to an output torque required to maintain a desired idle speed after the decrease of the load, and

the air decrease quantity calculating means including means for calculating the air decrease quantity in accordance with the desired air/fuel ratio after the decrease of the load, and the fuel decrease quantity.

3. An idle control system for controlling an idle speed of an internal combustion engine, the control system comprising:

load increasing operation request detecting means for detecting a load increasing operation request for an operation causing a increase of a load on the engine;

desired air/fuel ratio setting means for setting a desired air/fuel ratio of an air fuel mixture supplied to the engine in accordance with an engine operating condition;

fuel increase quantity calculating means for calculating a fuel increase quantity for increasing a fuel injection quantity in case of detection of the load increasing operation request;

air increase quantity calculating means for calculating an air increase quantity for increasing an air supply quantity in accordance with the desired air fuel ratio and the fuel increase quantity in case of detection of the load increasing operation request;

load controlling means for increasing the load in case of detection of the load increasing operation request;

fuel supply quantity correcting means for increasing the fuel injection quantity in accordance with the fuel increase quantity in case of detection of the load increasing operation request; and

air supply quantity correcting means for increasing the air supply quantity in accordance with the air increase quantity in case of detection of the load reducing operation request,

the load controlling means and the fuel quantity connecting means being timed so that there is a time difference between a load increasing operation of the load controlling means and a fuel increasing operation of the fuel supply quantity correcting means, to cause an actual increase of a load torque applied on the engine and an actual increase of an output torque of the engine to coincide with each other.

4. An idle speed control system for controlling an idle speed of an internal combustion engine, the control system comprising:

load increasing operation request detecting means for detecting a load increasing operation request for an operation causing a increase of a load on the engine;

desired air/fuel ratio setting means for setting a desired air/fuel ratio of an air fuel mixture supplied to the engine in accordance with an engine operating condition;

fuel increase quantity calculating means for calculating a fuel increase quantity for increasing a fuel injection quantity in case of detection of the load increasing operation request;

air increase quantity calculating means for calculating an air increase quantity for increasing an air supply quantity in accordance with the desired air fuel ratio and the fuel increase quantity in case of detection of the load increasing operation request;

load controlling means for increasing the load in case of detection of the load increasing operation request;

fuel supply quantity correcting means for increasing the fuel injection quantity in accordance with the fuel increase quantity in case of detection of the load increasing operation request; and

air supply quantity correcting means for increasing the air supply quantity in accordance with the air increase quantity in case of detection of the load reducing operation request,

the fuel increase quantity calculating means including means for calculating the fuel increase quantity corresponding to an output torque required to maintain a desired idle speed after the increase of the load, and

the air increase quantity calculating means including means for calculating the air increase quantity in accordance with a desired air/fuel ratio for an engine operating condition after an increase of the load, and the fuel increase quantity.