Engine exhaust purification device
AssigneeNissan Motor Co., Ltd.
InventorsHajime Oguma, Ritsuo Sato
Life of this patent
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Abstract
A controller controls an air-fuel ratio of an engine to maintain the oxygen storage amount of a catalyst provided in an exhaust passage at a predetermined amount. At this time, the controller first estimates the initial value of the oxygen storage amount based on the catalyst temperature on engine startup, and then computes an oxygen storage characteristic using this estimated initial value. In this way, the oxygen storage amount can be precisely computed even immediately after engine startup, and the conversion efficiency of the catalyst is maintained at a high level.
Claims11
An exhaust purification device for an engine, comprising:
- a catalyst provided in an exhaust passage of the engine;
- a first sensor which detects the characteristics of the exhaust flowing into the catalyst, and
- a microprocessor programmed to:
- estimate an oxygen storage amount of the catalyst on engine startup based on the temperature of the catalyst on engine startup,
- compute the oxygen storage amount of the catalyst based on the detected exhaust characteristics, using the oxygen storage amount on engine startup as an initial value, and
- control the air fuel ratio of the engine based on the computed oxygen storage amount so that the oxygen storage amount of the catalyst is a target value.
An exhaust purification device for an engine, comprising:
- a catalyst provided in an exhaust passage of the engine;
- means for detecting the characteristics of the exhaust flowing into the catalyst;
- means for estimating an oxygen storage amount of the catalyst on engine startup based on the temperature of the catalyst on engine startup;
- means for computing the oxygen storage amount of the catalyst based on the detected exhaust characteristics, using the oxygen storage amount on engine startup as an initial value, and
- means for controlling the air fuel ratio of the engine based on the computed oxygen storage amount so that the oxygen storage amount of the catalyst is a target value.
A method of estimating an oxygen storage amount of a catalyst provided in an exhaust passage of an engine, comprising:
- estimating the oxygen storage amount of the catalyst on engine startup based on the temperature of the catalyst on engine startup, and
- computing the oxygen storage amount of the catalyst based on the characteristics of the exhaust flowing into the catalyst, using the oxygen storage amount on engine startup as an initial value.
Dependencies are inferred from the claim text.