Diagnostic system for diagnosing deterioration of heated type oxygen sensor for internal combustion engines
First Claim
1. In a heated type oxygen sensor having a sensing element disposed in an exhaust passage for monitoring a content of oxygen contained within engine exhaust gases to generate an output signal in response to changes in the content of oxygen and a heating element inside for heating the sensing element, a diagnostic system for diagnosing deterioration of the oxygen sensor, comprising:
- a diagnostic zone setting means for setting a diagnostic zone;
a discrimination means being responsive to an engine temperature for discriminating that the engine is conditioned in one of a cold-engine state and a fully warmed-up state;
a first warm-up time setting means being responsive to input information from said discrimination means, for setting a predetermined oxygen sensor'"'"'s warm-up time at a first delay time (ta) which is preset to be suitable for the cold-engine state, only when said discrimination means determines that the engine is in the cold-engine state, and there is a transition from a heater energization zone to the diagnostic zone;
a second warm-up time setting means being responsive to the input information from said discrimination means, for setting said predetermined oxygen sensor'"'"'s warm-up time at a second delay time (tb) which is preprogrammed to be suitable for the fully warmed-up state, only when said discrimination means determines that the engine is in the fully warmed-up state, and there is a transition from a heater de-energization zone to the diagnostic zone; and
a diagnostic means for executing a diagnosis on deterioration of the oxygen sensor under a particular condition in which an elapsed time, measured from a time when the heating element is turned on, reaches said predetermined oxygen sensor'"'"'s warm-up time set by one of said first and second warm-up setting means.
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Accused Products
Abstract
In a heated type oxygen sensor having a sensing element responding to changes in the exhaust oxygen content and a heater inside, a diagnostic system for diagnosing deterioration of the heated type oxygen sensor comprises an electronic control unit being responsive to an engine temperature for discriminating whether the engine is in a cold-engine state or in a fully warmed-up state. The diagnostic system includes a first warm-up time setting circuit for setting a predetermined oxygen sensor'"'"'s warm-up time at a first delay time which is preset to be suitable for the cold-engine state, during cold-engine operations, and a second warm-up time setting circuit for setting the predetermined oxygen sensor'"'"'s warm-up time at a second delay time which is preprogrammed to be suitable for the fully warmed-up state, during fully warmed-up engine operations. The diagnostic system makes a diagnosis on deterioration of the oxygen sensor under a particular condition in which an elapsed time, measured from a time when the heater is turned on, reaches the predetermined oxygen sensor'"'"'s warm-up time set depending on during cold-engine operation or during fully warmed up engine operation.
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Citations
9 Claims
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1. In a heated type oxygen sensor having a sensing element disposed in an exhaust passage for monitoring a content of oxygen contained within engine exhaust gases to generate an output signal in response to changes in the content of oxygen and a heating element inside for heating the sensing element, a diagnostic system for diagnosing deterioration of the oxygen sensor, comprising:
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a diagnostic zone setting means for setting a diagnostic zone; a discrimination means being responsive to an engine temperature for discriminating that the engine is conditioned in one of a cold-engine state and a fully warmed-up state; a first warm-up time setting means being responsive to input information from said discrimination means, for setting a predetermined oxygen sensor'"'"'s warm-up time at a first delay time (ta) which is preset to be suitable for the cold-engine state, only when said discrimination means determines that the engine is in the cold-engine state, and there is a transition from a heater energization zone to the diagnostic zone; a second warm-up time setting means being responsive to the input information from said discrimination means, for setting said predetermined oxygen sensor'"'"'s warm-up time at a second delay time (tb) which is preprogrammed to be suitable for the fully warmed-up state, only when said discrimination means determines that the engine is in the fully warmed-up state, and there is a transition from a heater de-energization zone to the diagnostic zone; and a diagnostic means for executing a diagnosis on deterioration of the oxygen sensor under a particular condition in which an elapsed time, measured from a time when the heating element is turned on, reaches said predetermined oxygen sensor'"'"'s warm-up time set by one of said first and second warm-up setting means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for diagnosing deterioration of a heated type oxygen sensor, wherein the oxygen sensor includes a sensing element disposed in an exhaust passage for monitoring a content of oxygen contained within engine exhaust gases to generate an output signal in response to changes in the content of oxygen and a heating element inside for heating the sensing element, the method comprising:
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setting a diagnostic zone; discriminating, responsively to an engine temperature, that an engine is conditioned in one of a cold-engine state and a fully warmed-up state; setting, responsively to input information regarding which state the engine is in, an oxygen sensor'"'"'s warm-up time at a first delay time (ta) which is preset to be suitable for the cold-engine state, only when it is discriminated that the engine is in the cold-engine state, and there is a transition from a heater energization zone to the diagnostic zone; setting, responsively to the input information regarding which state the engine is in, said oxygen sensor'"'"'s warm-up time at a second delay time (tb) which is preprogrammed to be suitable for the fully warmed-up state, only when it is discriminated that the engine is in the fully warmed-up state, and there is a transition from a heater de-energization zone to the diagnostic zone; and executing a diagnosis on deterioration of the oxygen sensor under a particular condition in which an elapsed time, measured from a time when the heating element is turned on, reaches said oxygen sensor'"'"'s warm-up time set to either the first delay time or the second delay time.
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Specification