Catalyst diagnostic
First Claim
1. A diagnostic method for diagnosing a deterioration condition in an automotive internal combustion engine catalytic treatment device for catalytically treating internal combustion engine exhaust gas, comprising the steps of:
- guiding internal combustion engine exhaust gas to the catalytic treatment device for treatment by the catalytic treatment device;
estimating occurrence of a catalytic treatment device light-off condition in which an operable catalytic treatment device will reach a predetermined operating efficiency;
estimating actual operating efficiency of the catalytic treatment device when the light-off condition is estimated to have occurred;
comparing the actual operating efficiency to an expected operating efficiency; and
diagnosing a deterioration condition when the actual operating efficiency is less than the expected operating efficiency.
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Accused Products
Abstract
A procedure has been proposed for diagnosing operability of a catalytic treatment device for catalytically treating internal combustion engine exhaust gas, by determining whether the catalytic treatment device reaches a light-off operating condition within a short period of time following an engine coldstart operation. When catalytic converter temperature reaches a temperature level associated, for an operable catalytic converter, with light-off, the operating efficiency of the converter is sampled and, if persistently below an acceptable operating efficiency over a number of coldstart operations, a deterioration in the converter is stored and indicated.
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Citations
9 Claims
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1. A diagnostic method for diagnosing a deterioration condition in an automotive internal combustion engine catalytic treatment device for catalytically treating internal combustion engine exhaust gas, comprising the steps of:
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guiding internal combustion engine exhaust gas to the catalytic treatment device for treatment by the catalytic treatment device; estimating occurrence of a catalytic treatment device light-off condition in which an operable catalytic treatment device will reach a predetermined operating efficiency; estimating actual operating efficiency of the catalytic treatment device when the light-off condition is estimated to have occurred; comparing the actual operating efficiency to an expected operating efficiency; and diagnosing a deterioration condition when the actual operating efficiency is less than the expected operating efficiency. - View Dependent Claims (2, 3, 4, 5)
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6. In an automotive emissions control system including a catalytic converter for catalytically treating internal combustion engine exhaust gas passing therethrough, a method for diagnosing deterioration in the operability of the catalytic treatment device, comprising the steps of:
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generating a catalyst temperature value representative of the temperature of the catalytic converter; estimating a catalytic converter light-off time as a function of the catalyst temperature value; measuring catalytic converter operating efficiency at the light-off time; comparing the operating efficiency to a threshold efficiency level; and diagnosing deterioration in the operability of the catalytic converter when the operating efficiency does not exceed the threshold efficiency. - View Dependent Claims (7, 8, 9)
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Specification