Adaptive air/fuel ratio controller for internal combustion engine

• US 4,306,529 A
• Filed: 04/21/1980
• Issued: 12/22/1981
• Est. Priority Date: 04/21/1980
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Singer, David A., Zahorchak, John A., Chiesa, Alan F., Colden, Fayetta L.
• Primary Examiner(s): Myhre, Charles J.
• Assistant Examiner(s): Dolinar, Andrew M.
• Application Number:
  US06/142,332
• Time in Patent Office: 610 Days
• Field of Search: 123/440, 123/480, 123/486, 123/489, 123/491, 60/276, 60/285, 364/431
• US Class Current: 123/674
• CPC Class Codes: F02D 41/2445 characterised by a plurality of learning conditions or ranges
• CPC Class Codes: F02D 41/2454 Learning of the air-fuel ratio control
• CPC Class Codes: F02D 41/26 using computer, e.g. microprocessor

Abstract

An air/fuel ratio controller for an internal combustion engine including a memory having numbers stored at locations addressed by engine operating points with the locations addressed by the engine operating points being updated during closed loop operation in accord with the value of a closed loop adjustment of the air/fuel ratio. Each memory location in the memory is updated during operation of the engine at the corresponding operating point in accord with an update time constant having a value so that the number stored tracks adjustment value producing the predetermined desired closed loop air/fuel ratio during varying values of engine temperature. The update time constant is varied directly with the value of engine temperature so that the rate of adjustment of the numbers in the memory is greater during engine warmup where engine temperature increases rapidly. The memory is used during closed loop operation to preset the closed loop adjustment at least when the engine first operates at an operating point.

Claims

1. An adaptive closed loop air/fuel ratio controller for an internal combustion engine having supply means to supply a mixture of fuel and air to the engine and a sensor providing a sensor signal in response to the air/fuel ratio of the mixture supplied to the engine, the means to supply a mixture of air and fuel being characterized by the variations in the air/fuel ratio of the mixture supplied thereby in response to varying engine temperature, the controller including, in combination:

means effective to sense engine temperature;

a memory having numbers stored at locations addressable in accordance with an engine operating point determined by at least the value of engine load; and

means effective (a) to adjust the supply means in accord with the number stored in the memory at the location addressed by the engine operating point at least when the engine first operates at said operating point and, at least at some times, in accord with the sensor signal in a direction to establish a predetermined air/fuel ratio and (b) to adjust the number in the memory at the address corresponding to the engine operating point in a direction to cause correspondence with the value of the supply means adjustment and at a rate in accord with a predetermined time constant, the predetermined time constant having a value varying directly with the value of the sensed engine temperature, whereby the numbers in the memory are each updated substantially to the value producing the predetermined closed loop air/fuel ratio at the respective engine operating point during varying values of engine temperature and whereby the rate of adjustment of the numbers in the memory is greater during engine warmup where engine temperature increases rapidly.

2. An adaptive closed loop air/fuel ratio controller for an internal combustion engine having supply means to supply a mixture of fuel and air to the engine and a sensor providing a sensor signal in response to the air/fuel ratio of the mixture supplied to the engine, the means to supply a mixture of air and fuel being characterized by the variations in the air/fuel ratio of the mixture supplied thereby in response to varying engine temperature, the controller including, in combination:

means effective to sense engine temperature;

a memory having numbers stored at locations addressable in accordance with an engine operating point determined by at least the value of engine load;

means effective to recurrently (a) adjust the supply means in accord with the number stored in the memory at the location addressed by the engine operating point at least when the engine first operates at said operating point and, at least at some times, in accord with the sensor signal in a direction to establish a predetermined air/fuel ratio and (b) adjust the number in the memory at the address corresponding to the engine operating point in a direction to cause correspondence with the value of the supply means adjustment and by an amount determined by a time constant having a value varying directly with the value of the sensed engine temperature, whereby the numbers in the memory are each updated substantially to the value producing the predetermined closed loop air/fuel ratio at the respective engine operating point during varying values of engine temperature and whereby the rate of adjustment of the numbers in the memory is greater during engine warmup where engine temperature increases rapidly.

3. The method of controlling the air/fuel ratio in an internal combustion engine having supply means to supply a mixture of fuel and air to the engine and a sensor providing a sensor signal in response to the air/fuel ratio of the mixture supplied to the engine, the method including the steps of:

determining the engine operating point;

adjusting the supply means in accord with a number stored in a memory at a location addressed by the engine operating point at least when the engine first operates at said operating point and, at least at some times, in accord with the sensor signal in a direction to establish a predetermined closed loop air/fuel ratio; and

adjusting the number in the memory at a location addressed by the engine operating point in a direction to cause correspondence with the value of the supply means adjustment and at a rate directly proportional to the value of engine temperature so that the numbers in the memory are each updated substantially to the value producing the predetermined closed loop air/fuel ratio at the respective engine operating point during varying values of engine temperature and at a rate that is greater during colder engine temperatures where the rate of change of temperature is greater.