Electronic air-fuel ratio control apparatus in internal combustion engine
First Claim
1. An electronic air-fuel ratio control apparatus in an internal combustion engine with a ternary catalyst disposed in an exhaust system which is effective in oxidation reaction of carbon oxide and hydro carbon and in reduction reaction of nitrogen oxides when an air-fuel mixture sucked into the engine is in a theoretical air-fuel ratio, which comprises:
- an engine driving state-detecting means for detecting a driving state of the engine;
a nitrogen oxides concentration detecting means for detecting nitrogen oxides concentration in the exhaust gas;
an oxygen sensor disposed in the exhaust system of the engine to detect the air-fuel ratio of the air-fuel mixture through the oxygen concentration in the exhaust gas, said oxygen sensor comprising an oxidizing catalyst layer and a nitrogen oxides-reducing catalyst layer for promoting the reaction of reducing nitrogen oxides and emitting a voltage signal with the point of the theoretical air-fuel ratio corresponding to the oxygen concentration in the exhaust gas including the oxygen in the nitrogen oxides;
an air-fuel ratio feedback control means for controlling the air-fuel ratio of the air-fuel mixture by increasing or decreasing a fuel injection quantity to be supplied to the engine based on the engine driving state detected by said engine driving state-detecting means and the air-fuel ratio detected by said oxygen sensor so as to eliminate the deviation of the air-fuel ratio detected by said oxygen sensor from a target air-fuel ratio;
a fuel-injecting means for injecting and supplying a fuel to the engine in an on-off manner according to a driving pulse signal emitted from said air-fuel feedback control means; and
said air-fuel ratio feedback control means in which the target air-fuel ratio has first and second target air-fuel ratios and comprising;
a first target air-fuel ratio setting means for setting the first target air-fuel ratio based on the engine driving state detected by said engine driving state detecting means and the air-fuel ratio detected by said oxygen sensor;
a second target air-fuel ratio setting means for changing the first air-fuel ratio to set the second target air-fuel ratio richer than the first air-fuel ratio at least when the high nitrogen oxides concentration is detected by said nitrogen oxides concentration detecting means; and
a fuel injection quantity computing means for computing and setting a fuel injection quantity to be injected from said fuel-injecting means to the engine to attain the first target air-fuel ratio or the second target air-fuel ratio of the air-fuel mixture based on the engine driving state, the air-fuel ratio of the air-fuel mixture and the nitrogen oxide concentration.
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Accused Products
Abstract
An electronic air-fuel ratio control apparatus in an internal combustion engine provided with an oxygen sensor emitting an output voltage in response to an oxygen concentration including the same in nitrogen oxides in an exhaust gas from the engine which controls an air-fuel ratio of an air-fuel mixture by a feedback correction-control based on a oxygen sensor having the nitrogen oxides-reducing catalytic layer, the detection of a theoretical air-fuel ratio is performed on a richer side comparing with the output on the detection of a theoretical air-fuel ratio by an oxygen sensor without the nitrogen oxides-reducing function and is not changed even though the nitrogen oxides concentration changes. Accordingly the feedback air-fuel ratio control operates to decrease the amount of nitrogen oxides and to stabilize the air-fuel ratio control. A first target air-fuel ratio for the air-fuel ratio feedback control is changed to a second target air-fuel ratio which is richer than the first target air-fuel ratio at least when the high nitrogen oxide concentration in the exhaust gas is detected thereby changing of the controlled air-fuel ratio to the too much lean side is avoided.
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Citations
11 Claims
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1. An electronic air-fuel ratio control apparatus in an internal combustion engine with a ternary catalyst disposed in an exhaust system which is effective in oxidation reaction of carbon oxide and hydro carbon and in reduction reaction of nitrogen oxides when an air-fuel mixture sucked into the engine is in a theoretical air-fuel ratio, which comprises:
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an engine driving state-detecting means for detecting a driving state of the engine; a nitrogen oxides concentration detecting means for detecting nitrogen oxides concentration in the exhaust gas; an oxygen sensor disposed in the exhaust system of the engine to detect the air-fuel ratio of the air-fuel mixture through the oxygen concentration in the exhaust gas, said oxygen sensor comprising an oxidizing catalyst layer and a nitrogen oxides-reducing catalyst layer for promoting the reaction of reducing nitrogen oxides and emitting a voltage signal with the point of the theoretical air-fuel ratio corresponding to the oxygen concentration in the exhaust gas including the oxygen in the nitrogen oxides; an air-fuel ratio feedback control means for controlling the air-fuel ratio of the air-fuel mixture by increasing or decreasing a fuel injection quantity to be supplied to the engine based on the engine driving state detected by said engine driving state-detecting means and the air-fuel ratio detected by said oxygen sensor so as to eliminate the deviation of the air-fuel ratio detected by said oxygen sensor from a target air-fuel ratio; a fuel-injecting means for injecting and supplying a fuel to the engine in an on-off manner according to a driving pulse signal emitted from said air-fuel feedback control means; and said air-fuel ratio feedback control means in which the target air-fuel ratio has first and second target air-fuel ratios and comprising; a first target air-fuel ratio setting means for setting the first target air-fuel ratio based on the engine driving state detected by said engine driving state detecting means and the air-fuel ratio detected by said oxygen sensor; a second target air-fuel ratio setting means for changing the first air-fuel ratio to set the second target air-fuel ratio richer than the first air-fuel ratio at least when the high nitrogen oxides concentration is detected by said nitrogen oxides concentration detecting means; and a fuel injection quantity computing means for computing and setting a fuel injection quantity to be injected from said fuel-injecting means to the engine to attain the first target air-fuel ratio or the second target air-fuel ratio of the air-fuel mixture based on the engine driving state, the air-fuel ratio of the air-fuel mixture and the nitrogen oxide concentration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An electronic air-fuel ratio control apparatus in an internal combustion engine with a ternary catalyst disposed in an exhaust system which is effective in oxidation reaction of carbon oxide and hydro-carbons and in reduction reaction of nitrogen oxides when an air-fuel mixture sucked into the engine is a theoretical air-fuel ratio, which includes:
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an engine driving state-detecting means for detecting a driving state of the engine; an oxygen sensor disposed in the exhaust system of the engine to detect the air-fuel ratio of the air-fuel mixture through the oxygen concentration in the exhaust gas; an air-fuel ratio feedback control means for controlling the air-fuel ratio of the air-fuel mixture by increasing or decreasing a fuel injection quantity to be supplied to the engine based on the engine driving state detected by said engine driving state-detecting means and the air-fuel ratio detected by said oxygen sensor so as to eliminate the deviation of the air-fuel ratio detected by said oxygen sensor from a target air-fuel ratio; and a fuel-injecting means for injecting and supplying a fuel to the engine in an on-off manner according to a driving pulse signal emitted from said air-fuel feedback control means; characterized in that; said oxygen sensor comprises a nitrogen oxides-reducing catalyst layer for promoting the reaction of reducing nitrogen oxides and emitting a voltage signal with the point of the theoretical air-fuel ratio corresponding to the oxygen concentration in the exhaust gas including the oxygen in the nitrogen oxides, and said air-fuel ratio feedback control means has first and second target air-fuel ratios as said target air-fuel ratio and comprises; a first target air-fuel ratio setting means for setting the first target air-fuel ratio based on the engine driving state detected by said engine driving state detecting means and the air-fuel ratio detected by said oxygen sensor; a second target air-fuel ratio setting means for changing the first air-fuel ratio to set the second target air-fuel ratio richer than the first air-fuel ratio at least when the high nitrogen oxides concentration is detected by said nitrogen oxides concentration detecting means; and a fuel injection quantity computing means for computing and setting a fuel injection quantity to be injected from said fuel-injecting means to the engine to attain the first target air-fuel ratio or the second target air-fuel ratio of the air-fuel mixture based on the engine driving state, the air-fuel ratio of the air-fuel mixture and the nitrogen oxide concentration.
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Specification