Air-fuel ratio control system for internal combustion engines, having catalytic converter deterioration-detecting function
First Claim
1. An air-fuel ratio control system for an internal combustion engine having an exhaust system, and catalytic converter means arranged in said exhaust system, comprising:
- first and second air-fuel ratio sensor means arranged in said exhaust system upstream and downstream of said catalytic converter means, respectively;
air-fuel ratio correction amount-calculating means for calculating an air-fuel ratio correction amount, based at least on an output from said first air-fuel ratio sensor means,catalytic converter deterioration-detecting means for detecting deterioration of said catalytic converter means, based on an output from said second air-fuel ratio sensor means when the engine is in a predetermined operating condition; and
deterioration detection-inhibiting means for inhibiting operation of said catalytic converter deterioration-detecting means when said air-fuel ratio correction amount falls outside a predetermined range.
1 Assignment
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Accused Products
Abstract
An air-fuel ratio control system for an internal combustion engine having a catalytic converter arranged in the exhaust system, and first and second air-fuel ratio sensors arranged upstream and downstream of the catalytic converter respectively has an ECU which calculates an air-fuel ratio correction amount, based at least on an output from the first air-fuel ratio sensor, and detects deterioration of the catalytic converter, based on an output from the second air-fuel ratio sensor when the engine is in a predetermined operating condition. The ECU inhibits detection of deterioration of the catalytic converter when the air-fuel ratio correction amount falls outside a predetermined range.
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Citations
6 Claims
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1. An air-fuel ratio control system for an internal combustion engine having an exhaust system, and catalytic converter means arranged in said exhaust system, comprising:
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first and second air-fuel ratio sensor means arranged in said exhaust system upstream and downstream of said catalytic converter means, respectively; air-fuel ratio correction amount-calculating means for calculating an air-fuel ratio correction amount, based at least on an output from said first air-fuel ratio sensor means, catalytic converter deterioration-detecting means for detecting deterioration of said catalytic converter means, based on an output from said second air-fuel ratio sensor means when the engine is in a predetermined operating condition; and deterioration detection-inhibiting means for inhibiting operation of said catalytic converter deterioration-detecting means when said air-fuel ratio correction amount falls outside a predetermined range. - View Dependent Claims (2, 3, 4, 5)
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6. An air-fuel ratio control system for an internal combustion engine having an exhaust system, and catalytic converter means arranged in said exhaust system, comprising:
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air-fuel ratio sensor means arranged in said exhaust system downstream of said catalytic converter means; air-fuel ratio correction amount-calculating means for calculating an air-fuel ratio correction amount, based at least on an output from said air-fuel ratio sensor means; catalytic converter deterioration-detecting means for detecting deterioration of said catalytic converter means, based on said output from said air-fuel ratio sensor means when the engine is in a predetermined operating condition; and deterioration detection-inhibiting means for inhibiting operation of said catalytic converter deterioration-detecting means when said air-fuel ratio correction amount falls outside a predetermined range.
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Specification