Diagnostic apparatus for use in an exhaust system of an internal combustion engine
First Claim
1. A diagnostic apparatus for use in an exhaust system of an internal combustion engine, the exhaust system having an exhaust gas passage, a catalyst for purifying the exhaust gas in the exhaust gas passage and an oxygen sensor for detecting an air-fuel ratio in a combustion chamber, wherein a fuel injection volume is controlled for equalizing a primary air-fuel ratio with a predetermined theoretical air-fuel ratio when the engine is operated under normal conditions, and wherein secondary air is supplied to the exhaust gas passage from a secondary air supply mechanism for forcibly adjusting the air-fuel ratio when the engine is operating under extreme conditions, wherein the secondary supply mechanism is composed of a plurality of members, said apparatus comprising:
- means for computing an actual volume flow rate of the secondary air supplied to the exhaust gas passage from the secondary air supply mechanism;
means for storing data indicative of the malfunctioning of the secondary air supply mechanism members corresponding to the computed volume flow rate supplied to the exhaust gas passage;
means for determining which member of the secondary air supply mechanism is malfunctioning based on the value detected by the oxygen sensor and the stored data.
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Accused Products
Abstract
A diagnostic apparatus for use in an exhaust system of an internal combustion engine is disclosed. The system has a catalyst for purifying the exhaust gas in the exhaust gas passage and an oxygen sensor for detecting an air-fuel ratio in a combustion chamber, wherein fuel injection volume is controlled for optimizing the air-fuel ratio and the catalyst activation when the engine is operated under normal conditions, and wherein secondary air is supplied to the exhaust gas passage from a secondary air supply mechanism for forcibly adjusting the air-fuel ratio when the engine is operating under extreme conditions. The apparatus has a computing device which computes an actual volume of the secondary air supplied to the exhaust gas passage from the secondary air supply mechanism. The apparatus further has a storing device which stores data indicative of malfuncting secondary air supply mechanism members corresponding to the computed volume supplied to the exhausted gas passage, and a determining device for determining the malfunctioning member in accordance with the value detected by the oxygen sensor and the stored data corresponding the detected value.
35 Citations
21 Claims
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1. A diagnostic apparatus for use in an exhaust system of an internal combustion engine, the exhaust system having an exhaust gas passage, a catalyst for purifying the exhaust gas in the exhaust gas passage and an oxygen sensor for detecting an air-fuel ratio in a combustion chamber, wherein a fuel injection volume is controlled for equalizing a primary air-fuel ratio with a predetermined theoretical air-fuel ratio when the engine is operated under normal conditions, and wherein secondary air is supplied to the exhaust gas passage from a secondary air supply mechanism for forcibly adjusting the air-fuel ratio when the engine is operating under extreme conditions, wherein the secondary supply mechanism is composed of a plurality of members, said apparatus comprising:
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means for computing an actual volume flow rate of the secondary air supplied to the exhaust gas passage from the secondary air supply mechanism; means for storing data indicative of the malfunctioning of the secondary air supply mechanism members corresponding to the computed volume flow rate supplied to the exhaust gas passage; means for determining which member of the secondary air supply mechanism is malfunctioning based on the value detected by the oxygen sensor and the stored data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A diagnostic apparatus for use in an exhaust system of an internal combustion engine, the exhaust system having an exhaust gas passage, a catalyst for purifying the exhaust gas in the exhaust gas passage and an oxygen sensor for detecting an air-fuel ratio in a combustion chamber, wherein a fuel injection volume is controlled for optimizing the air-fuel ratio and the catalyst activation when the engine is operated under normal conditions, and wherein secondary air is supplied to the exhaust gas passage from a secondary air supply mechanism for forcibly adjusting the air-fuel ratio when the engine is operating under extreme conditions, wherein the secondary supply mechanism is composed of a plurality of members, said apparatus comprising:
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means for computing an actual volume flow rate of the secondary air supplied to the exhaust gas passage by rectifying a volume of air sucked into the combustion chamber with coefficients relating to engine operation conditions and a stoichiometric air-fuel ratio; air value data storing means for storing a standard secondary air supply value for every engine rotation speed, the standard secondary air supply value corresponding to the secondary air supplied to the exhaust gas passage from the secondary air supply mechanism; data storing means for storing data indicative of the malfunctioning of the secondary air supply mechanism members corresponding to a difference between the actual secondary air supply value and the standard air supply value; means for determining which member of the secondary air supply mechanism is malfunctioning based on the value detected by the oxygen sensor and the stored data. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A diagnostic apparatus for use in an exhaust system of an internal combustion engine, the exhaust system having an exhaust gas passage, a catalyst for purifying the exhaust gas in the exhaust gas passage and an oxygen sensor for detecting an air-fuel ratio in a combustion chamber, wherein a-fuel injection volume is controlled for optimizing the air-fuel ratio and the catalyst activation when the engine is operated under normal conditions, and wherein secondary air is supplied to the exhaust gas passage from a secondary air supply mechanism for forcibly adjusting the air-fuel ratio when the engine is operating under extreme conditions, wherein the secondary supply mechanism is composed of a plurality of members, said apparatus comprising:
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a plurality of sensors for sensing engine operation conditions, said engine conditions including at least a temperature of air flowing in an intake passage, a temperature of engine coolant and the engine rotation velocity; an air flow meter for detecting a volume of air sucked into the combustion chamber; a data memory for storing a standard secondary air supply value for every engine rotation velocity; a controller for computing an actual volume of the secondary air supplied to the exhaust gas passage by rectifying a volume of air sucked into the combustion chamber with coefficients relating to engine operation conditions and stoichiometric air-fuel ratio, and for determining which of the secondary air supply mechanism members is malfunctioning based on a difference between the actual secondary air supply value and the standard secondary air supply value stored for the detected engine rotation speed. - View Dependent Claims (18, 19, 20, 21)
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Specification