摘要:
A catalyst 3 which has oxygen storage performance is installed in an engine exhaust passage 2, an oxygen storage amount is estimated based on the output of an upstream air-fuel ratio sensor 4 installed in the upstream of the catalyst 3, and an air-fuel ratio is controlled so that this oxygen storage amount coincides with a target value. When the output of a downstream air-fuel ratio sensor 5 has become lean or rich for longer than a fixed time, the output of the upstream air-fuel ratio sensor 4 is corrected based on the output of the downstream air-fuel ratio sensor 5 placed in the downstream of the catalyst 3. In this way, the output fluctuation due to deterioration of the air-fuel ratio sensor 4 upstream of the catalyst is corrected, and the catalyst oxygen storage amount is always precisely controlled to the target value.
摘要:
A catalyst 3 which has oxygen storage performance is installed in an engine exhaust passage 2, an oxygen storage amount is estimated based on the output of an upstream air-fuel ratio sensor 4 installed in the upstream of the catalyst 3, and an air-fuel ratio is controlled so that this oxygen storage amount coincides with a target value. When the output of a downstream air-fuel ratio sensor 5 has become lean or rich for longer than a fixed time, the output of the upstream air-fuel ratio sensor 4 is corrected based on the output of the downstream air-fuel ratio sensor 5 placed in the downstream of the catalyst 3. In this way, the output fluctuation due to deterioration of the air-fuel ratio sensor 4 upstream of the catalyst is corrected, and the catalyst oxygen storage amount is always precisely controlled to the target value.
摘要:
A catalytic converter. (3) having a three-way catalyst which stores oxygen is disposed in the exhaust passage (2) of an engine (1). An oxygen storage amount of the catalyst is estimated based on the output of a universal exhaust gas oxygen sensor (4) provided upstream of the catalytic converter (3). A control unit (6) controls an air-fuel ratio of the fuel mixture supplied to the engine (1) through a fuel injector (12) so that the oxygen storage amount coincides with a target value. An excess/deficiency oxygen amount in the exhaust gas is accumulated when the output of an oxygen sensor (5) which detects the oxygen concentration downstream of the catalytic converter (3) is in an excess oxygen region which is higher than a stoichiometric oxygen concentration region. An average oxygen excess ratio is calculated by dividing the accumulated value by an accumulated intake air amount. The output of the universal exhaust gas oxygen sensor (4) is corrected based on the average oxygen excess ratio. In the same manner, the output of the universal exhaust gas oxygen sensor (4) is corrected based on the average oxygen excess ratio when the output of the oxygen sensor (5) is in an deficiency oxygen region which is lower than the stoichiometric oxygen concentration region. These corrections compensate for fluctuations in the output resulting from deterioration of the universal exhaust gas oxygen sensor (4) or due to manufacturing errors and the calculation accuracy of the oxygen storage amount of the catalyst is thereby increased.
摘要:
A catalytic converter. (3) having a three-way catalyst which stores oxygen is disposed in the exhaust passage (2) of an engine (1). An oxygen storage amount of the catalyst is estimated based on the output of a universal exhaust gas oxygen sensor (4) provided upstream of the catalytic converter (3). A control unit (6) controls an air-fuel ratio of the fuel mixture supplied to the engine (1) through a fuel injector (12) so that the oxygen storage amount coincides with a target value. An excess/deficiency oxygen amount in the exhaust gas is accumulated when the output of an oxygen sensor (5) which detects the oxygen concentration downstream of the catalytic converter (3) is in an excess oxygen region which is higher than a stoichiometric oxygen concentration region. An average oxygen excess ratio is calculated by dividing the accumulated value by an accumulated intake air amount. The output of the universal exhaust gas oxygen sensor (4) is corrected based on the average oxygen excess ratio. In the same manner, the output of the universal exhaust gas oxygen sensor (4) is corrected based on the average oxygen excess ratio when the output of the oxygen sensor (5) is in an deficiency oxygen region which is lower than the stoichiometric oxygen concentration region. These corrections compensate for fluctuations in the output resulting from deterioration of the universal exhaust gas oxygen sensor (4) or due to manufacturing errors and the calculation accuracy of the oxygen storage amount of the catalyst is thereby increased.
摘要:
An oxygen storage amount of the catalyst (3) is estimated using a detection result from a front A/F sensor (4). An HC storage amount is calculated as a time integral of the product of the storage rate by the catalyst (3), the air-fuel ratio and the intake air amount, and a target air-fuel ratio is corrected so that a deficiency relative to a target amount of the oxygen storage amount is compensated based on this computation result.
摘要:
An oxygen storage amount of the catalyst (3) is estimated using a detection result from a front A/F sensor (4). An HC storage amount is calculated as a time integral of the product of the storage rate by the catalyst (3), the air-fuel ratio and the intake air amount, and a target air-fuel ratio is corrected so that a deficiency relative to a target amount of the oxygen storage amount is compensated based on this computation result.