Air-fuel ratio control system
First Claim
1. An air-fuel ratio control system for an engine, comprising:
- means for detecting air-fuel ratio of air-fuel mixture to be inducted to the engine;
means for detecting operating condition of the engine;
means for calculating an air-fuel ratio correction coefficient in accordance with said detected air-fuel ratio;
means for accomplishing feedback control of the air-fuel ratio into a stoichiometric value in accordance with said air-fuel ratio correction coefficient;
means for forming a plurality of learning areas defined respectively by engine operating conditions, learning being able to be made in each learning area, at least a part of each learning area being under said feedback control and at least one of said learning areas having a part which is never under feedback control;
means for calculating a learning coefficient for said learning area corresponding to said detected engine operating condition, in accordance with said air-fuel ratio correction coefficient under said feedback control, said learning coefficient being memorized in said at least a part of each learning area; and
means for accomplishing feedforward control of the air-fuel ratio into a lean value which is leaner than said stoichiometric value, in accordance with said learning coefficient.
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Accused Products
Abstract
An air-fuel ratio control system for controlling the air-fuel ratio of air-fuel mixture to be inducted into an automotive engine in order to accomplish feedback control of the air-fuel ratio into a stoichiometric level of feedforward control of the air-fuel ratio into a lean level. The air-fuel ratio control system is comprised of a control unit which is electrically connected to an oxygen sensor for detecting the air-fuel ratio and to a variety of sensors for detecting engine operating condition. The control unit is adapted to calculate an air-fuel ratio correction coefficient in accordance with the detected air-fuel ratio. The feedback control of the air-fuel ratio is accomplished in accordance with the air-fuel ratio correction coefficient. The control unit is further adapted to form a plurality of learning areas defined respectively by engine operating conditions. Learning is made in each learning area. At least a part of each learning area is under the feedback control. The control unit is adapted to further calculate a learning coefficient for the learning area corresponding to the detected engine operating condition, in accordance with the air-fuel ratio correction coefficient under the feedback control. The learning coefficient is memorized in the above-mentioned at least a part of each learning area. The feedforward control of the air-fuel ratio is accomplished in accordance with the learning coefficient in the learning area corresponding to the detected engine operating condition, thereby improving the precision of control in the feedforward control of the air-fuel ratio.
85 Citations
11 Claims
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1. An air-fuel ratio control system for an engine, comprising:
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means for detecting air-fuel ratio of air-fuel mixture to be inducted to the engine; means for detecting operating condition of the engine; means for calculating an air-fuel ratio correction coefficient in accordance with said detected air-fuel ratio; means for accomplishing feedback control of the air-fuel ratio into a stoichiometric value in accordance with said air-fuel ratio correction coefficient; means for forming a plurality of learning areas defined respectively by engine operating conditions, learning being able to be made in each learning area, at least a part of each learning area being under said feedback control and at least one of said learning areas having a part which is never under feedback control; means for calculating a learning coefficient for said learning area corresponding to said detected engine operating condition, in accordance with said air-fuel ratio correction coefficient under said feedback control, said learning coefficient being memorized in said at least a part of each learning area; and means for accomplishing feedforward control of the air-fuel ratio into a lean value which is leaner than said stoichiometric value, in accordance with said learning coefficient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification