Method of detecting failure of humidity sensor
First Claim
1. A method of detecting a failure of a humidity sensor in an exhaust system having a hydrocarbon adsorbent disposed in an exhaust passage of an internal combustion engine for adsorbing hydrocarbons contained in an exhaust gas emitted from the internal combustion engine, said humidity sensor being disposed in said exhaust passage for detecting a humidity in the exhaust passage near the hydrocarbon adsorbent, said method comprising the step of:
- detecting whether or not said humidity sensor has failed based on an output signal of the humidity sensor within a predetermined period in which the output signal of the humidity sensor is substantially constant and a humidity represented by the output signal of the humidity sensor is not converged to a humidity outside of said exhaust passage, after said internal combustion engine is shut off.
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Abstract
A humidity sensor is disposed near an HC adsorbent in an exhaust system of an internal combustion engine. After the internal combustion engine is shut off, it is detected whether or not the humidity sensor has failed based on the value of the humidity detected by the humidity sensor when the detected value of the humidity is substantially constant, by determining whether or not the detected value of the humidity falls in a range between upper and lower limit thresholds that are set depending on the temperature near the HC adsorbent. It is stably and easily detected whether or not the humidity sensor disposed near the HC adsorbent in the exhaust system of the internal combustion engine has failed.
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8 Claims
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1. A method of detecting a failure of a humidity sensor in an exhaust system having a hydrocarbon adsorbent disposed in an exhaust passage of an internal combustion engine for adsorbing hydrocarbons contained in an exhaust gas emitted from the internal combustion engine, said humidity sensor being disposed in said exhaust passage for detecting a humidity in the exhaust passage near the hydrocarbon adsorbent, said method comprising the step of:
detecting whether or not said humidity sensor has failed based on an output signal of the humidity sensor within a predetermined period in which the output signal of the humidity sensor is substantially constant and a humidity represented by the output signal of the humidity sensor is not converged to a humidity outside of said exhaust passage, after said internal combustion engine is shut off. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
Specification