Exhaust purification apparatus for an engine
AssigneeMazda Motor Corporation
InventorsKazunari Komatsu, Kiyoshi Kuronishi, Naoyuki Noguchi, Hirofumi Nishimura
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Abstract
An exhaust purification apparatus for an engine uses a catalytic converter provided in an exhaust system of the engine. First and second exhaust sensors are provided on upstream and downstream sides, respectively, of the catalyst converter in the exhaust system. Detected values from the first and second exhaust sensors are used for feed back control of air fuel ratio and judging deterioration of the catalyst of the catalytic converter, respectively. A control constant of the air fuel ratio of the feed back control is changed so that the second exhaust sensor detects in accordance with a condition of the catalyst.
Claims9
An exhaust purification apparatus for an engine comprising:
- a catalytic converter located in an exhaust system of the engine for purifying exhaust gas from the engine;
- first exhaust sensor means for detecting concentration of remaining oxygen in the exhaust gas and provided in the exhaust system on an upstream side of said catalytic converter;
- second exhaust sensor means for detecting concentration of remaining oxygen in said exhaust gas and provided in the exhaust system on a downstream side of said catalytic converter;
- feed back control means for controlling an air fuel ratio of said engine in response to a detected value of said first exhaust sensor means and a predetermined control constant;
- operating condition detecting means for detecting a predetermined operating state of the engine suitable for judging deterioration of a catalyst in said catalytic converter;
- deterioration judging means for judging deterioration of a catalyst in said catalytic converter on the basis of a detected value of said second sensor means when said operating condition detecting means detects said predetermined operating state of said engine;
- and
- control constant changing means for changing a control constant of said air fuel ratio of said feed back control means from the predetermined control constant when the deterioration judging means judges deterioration of said catalyst.
Dependencies are inferred from the claim text.