Exhaust emission control system in internal combustion engine
First Claim
1. An exhaust emission control system in an internal combustion engine comprising a spark plug disposed to face a combustion chamber, an intake system in which a fuel injection valve is disposed, an exhaust system having a catalytic converter incorporated therein and filled with a catalyst for reducing nitrogen oxide (NOx) in the presence of hydrocarbons in an oxidizing atmosphere, and an exhaust gas circulation amount control means capable of controlling the amount of exhaust gas circulated from the exhaust system to the intake system, said control system further comprising:
- a revolution-number detector for detecting a number of revolutions of the engine;
a load detector for detecting an engine load;
a nitrogen oxide detector mounted in the exhaust system at a location downstream from the catalytic converter for detecting an amount of discharged nitrogen oxide (NOx); and
a control unit having means for determining an acceptable amount of NOx to be discharged in the exhaust gas based on said detected number of revolutions of the engine and said detected engine load, and said control unit having means for controlling the amount of exhaust gas circulated by the exhaust gas circulation amount control means, the amount and timing of fuel injected by the fuel injection valve and the timing of ignition of the spark plug, such that the amount of NOx discharged as detected by said nitrogen oxide detector becomes equal to or less than said determined acceptable amount of NOx to be discharged.
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Accused Products
Abstract
In an exhaust emission control system in an internal combustion engine which includes a spark plug disposed to face a combustion chamber, an intake system having a fuel injection valve disposed therein, an exhaust system having a catalytic converter incorporated therein and filled with a catalyst for reducing nitrogen oxide (NOx) in the presence of hydrocarbons in an oxidizing atmosphere, and an exhaust gas circulation amount control means capable of measuring and controlling the amount of exhaust gas circulated from the exhaust system to the intake system. The amount of exhaust gas circulated by the exhaust gas circulation amount control means the amount and timing of fuel injected by the fuel injection valve and the timing of ignition of the spark plug are controlled by a control unit, so that the amount of NOx discharged, is detected by the NOx detector in the exhaust system at a location downstream from the catalytic converter, is equal to or less than an acceptable amount of NOx discharged which acceptable amount is set in accordance with the number of revolutions of the engine detected by a revolution-number detector as well as the engine load detected by a load detector. Thus, it is possible to control the concentration and type of hydrocarbons and the temperature of the catalyst to increase the elimination rate of NOx.
40 Citations
15 Claims
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1. An exhaust emission control system in an internal combustion engine comprising a spark plug disposed to face a combustion chamber, an intake system in which a fuel injection valve is disposed, an exhaust system having a catalytic converter incorporated therein and filled with a catalyst for reducing nitrogen oxide (NOx) in the presence of hydrocarbons in an oxidizing atmosphere, and an exhaust gas circulation amount control means capable of controlling the amount of exhaust gas circulated from the exhaust system to the intake system, said control system further comprising:
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a revolution-number detector for detecting a number of revolutions of the engine; a load detector for detecting an engine load; a nitrogen oxide detector mounted in the exhaust system at a location downstream from the catalytic converter for detecting an amount of discharged nitrogen oxide (NOx); and a control unit having means for determining an acceptable amount of NOx to be discharged in the exhaust gas based on said detected number of revolutions of the engine and said detected engine load, and said control unit having means for controlling the amount of exhaust gas circulated by the exhaust gas circulation amount control means, the amount and timing of fuel injected by the fuel injection valve and the timing of ignition of the spark plug, such that the amount of NOx discharged as detected by said nitrogen oxide detector becomes equal to or less than said determined acceptable amount of NOx to be discharged. - View Dependent Claims (2, 7, 8)
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3. In an exhaust emission control system in an internal combustion engine comprising a spark plug disposed to face a combustion chamber, an intake system in which a fuel injection valve is disposed, an exhaust system having a catalytic converter incorporated therein and filled with a catalyst for reducing nitrogen oxide (NOx) in the presence of hydrocarbons in an oxidizing atmosphere, an exhaust gas circulation amount control means capable of controlling the amount of exhaust gas circulated from the exhaust system to the intake system, a revolution-number detector for detecting the number of revolutions of the engine, and a load detector for detecting the load on the engine, an improvement in the control system comprising:
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a nitrogen oxide detector mounted in the exhaust system at a location downstream from the catalytic converter for detecting an amount of discharged nitrogen oxide (NOx); and control means for determining an acceptable amount of NOx to be discharged in the exhaust gas based on the detected number of revolutions of the engine and the detected engine load, and said control means having means for controlling at least one of the amount of exhaust gas circulated by the exhaust gas circulation amount control means, the amount of fuel injected by the fuel injection valve, the timing of fuel injected by the fuel injection valve and the timing of ignition of the spark plug for causing the amount of NOx being discharged, as detected by said nitrogen oxide detector, to become equal to or less than said determined acceptable amount of NOx to be discharged. - View Dependent Claims (4, 5, 6, 9, 10)
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11. An exhaust emission control method for an internal combustion engine having a spark plug disposed to face a combustion chamber, an intake system in which a fuel injection valve is disposed, an exhaust system having a catalytic converter incorporated therein and filled with a catalyst for reducing nitrogen oxide (NOx) in the presence of hydrocarbons in an oxidizing atmosphere, an exhaust gas circulation amount control means capable of controlling the amount of exhaust gas circulated from the exhaust system to the intake system a revolution-number detector for detecting the number of revolutions of the engine, and a load detector for detecting the load on the engine, the method comprising steps of:
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detecting an amount of discharged nitrogen oxide (NOx) in the exhaust system downstream from the catalytic converter; determining an acceptable amount of NOx to be discharged in the exhaust gas based on the detected engine load and number of revolutions of the engine, and controlling at least one of the amount of exhaust gas circulated by the exhaust gas circulation amount control means, the amount of fuel injected by the fuel injection valve, the timing of fuel injected by the fuel injection valve and the timing of ignition of the spark plug for causing the amount of NOx being discharged, as detected by said nitrogen oxide detector, to become equal to or less than said predetermined acceptable amount of NOx to be discharged. - View Dependent Claims (12, 13, 14, 15)
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Specification