Air-fuel ratio control system for internal combustion engine
First Claim
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1. An air-fuel ratio control system for an internal combustion engine, comprising:
- an exhaust gas sensor disposed downstream of a catalytic converter in an exhaust passage of the internal combustion engine, for detecting the concentration of a particular component of an exhaust gas having passed through the catalytic converter;
manipulated variable generating means for sequentially generating a manipulated variable which manipulates the air-fuel ratio of an air-fuel mixture combusted by the internal combustion engine in order to converge an output from said exhaust gas sensor to a predetermined target value; and
limiting means for limiting the manipulated variable generated by said manipulated variable generating means to a value in a predetermined allowable range, for thereby making the air-fuel ratio of the air-fuel mixture to be determined based on the manipulated variable;
said limiting means comprising means for variably setting the allowable range depending on the manipulated variable generated by said manipulated variable generating means;
wherein said limiting means comprises means for, if the value of the manipulated variable generated by said manipulated variable generating means deviates from said allowable range beyond an upper or lower limit thereof, changing the limit beyond which the manipulated variable deviates, in a direction to increase said allowable range for thereby updating the allowable range.
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Abstract
An allowable range (adaptive allowable range) for limiting a manipulated variable generated in order to converge the difference between an output from an O2 sensor disposed downstream of a catalytic converter and a target value thereof to “0” is sequentially updated depending on how the manipulated variable deviates from the allowable range.
33 Citations
35 Claims
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1. An air-fuel ratio control system for an internal combustion engine, comprising:
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an exhaust gas sensor disposed downstream of a catalytic converter in an exhaust passage of the internal combustion engine, for detecting the concentration of a particular component of an exhaust gas having passed through the catalytic converter;
manipulated variable generating means for sequentially generating a manipulated variable which manipulates the air-fuel ratio of an air-fuel mixture combusted by the internal combustion engine in order to converge an output from said exhaust gas sensor to a predetermined target value; and
limiting means for limiting the manipulated variable generated by said manipulated variable generating means to a value in a predetermined allowable range, for thereby making the air-fuel ratio of the air-fuel mixture to be determined based on the manipulated variable;
said limiting means comprising means for variably setting the allowable range depending on the manipulated variable generated by said manipulated variable generating means;
wherein said limiting means comprises means for, if the value of the manipulated variable generated by said manipulated variable generating means deviates from said allowable range beyond an upper or lower limit thereof, changing the limit beyond which the manipulated variable deviates, in a direction to increase said allowable range for thereby updating the allowable range. - View Dependent Claims (2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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5. An air-fuel ratio control system for an internal combustion engine, comprising:
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an exhaust gas sensor disposed downstream of a catalytic converter in an exhaust passage of the internal combustion engine, for detecting the concentration of a particular component of an exhaust gas having passed through the catalytic converter;
manipulated variable generating means for sequentially generating a manipulated variable which manipulates the air-fuel ratio of an air-fuel mixture combusted by the internal combustion engine in order to converge an output from said exhaust gas sensor to a predetermined target value; and
limiting means for limiting the manipulated variable generated by said manipulated variable generating means to a value in a predetermined allowable range, for thereby making the air-fuel ratio of the air-fuel mixture to be determined based on the manipulated variable;
said limiting means comprising means for variably setting the allowable range depending on the manipulated variable generated by said manipulated variable generating means;
wherein said limiting means comprises means for changing an upper limit of said allowable range in a direction to increase or reduce said allowable range depending on whether the value of the manipulated variable generated by said manipulated variable generating means is larger than said upper limit or not, and changing a lower limit of said allowable range in a direction to increase or decrease said allowable range depending on whether the value of the manipulated variable generated by said manipulated variable generating means is smaller than said lower limit or not, for thereby updating the allowable range.
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15. An air-fuel ratio control system for an internal combustion engine, comprising:
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an exhaust gas sensor disposed downstream of a catalytic converter in an exhaust passage of the internal combustion engine, for detecting the concentration of a particular component of an exhaust gas having passed through the catalytic converter;
manipulated variable generating means for sequentially generating a manipulated variable which manipulates the air-fuel ratio of an air-fuel mixture combusted by the internal combustion engine in order to converge an output from said exhaust gas sensor to a predetermined target value; and
limiting means for limiting the manipulated variable generated by said manipulated variable generating means to a value in a predetermined allowable range, for thereby making the air-fuel ratio of the air-fuel mixture to be determined based on the manipulated variable;
said limiting means comprising means for variably setting the allowable range depending on the manipulated variable generated by said manipulated variable generating means;
wherein the manipulated variable generated by said manipulated variable generating means and the upper and lower limits of said allowable range represent differences with a predetermined reference value for the air-fuel ratio of the air-fuel mixture, further comprising reference value variable setting means for variably setting said reference value depending on the manipulated variable generated by said manipulated variable generating means. - View Dependent Claims (16, 17, 18, 19, 20, 31, 32, 33, 34, 35)
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21. An air-fuel ratio control system for an internal combustion engine, comprising:
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an exhaust gas sensor disposed downstream of a catalytic converter in an exhaust passage of the internal combustion engine, for detecting the concentration of a particular component of an exhaust gas having passed through the catalytic converter;
manipulated variable generating means for sequentially generating a manipulated variable which manipulates the air-fuel ratio of an air-fuel mixture combusted by the internal combustion engine in order to converge an output from said exhaust gas sensor to a predetermined target value; and
limiting means for limiting the manipulated variable generated by said manipulated variable generating means to a value in a predetermined allowable range, for thereby making the air-fuel ratio of the air-fuel mixture to be determined based on the manipulated variable;
said limiting means comprising means for variably setting the allowable range depending on the manipulated variable generated by said manipulated variable generating means, and means for recognizing an operating state of said internal combustion engine, and setting said allowable range depending on the recognized operating state;
wherein said exhaust gas sensor comprises an oxygen concentration sensor, and said operating state of the internal combustion engine recognized by said limiting means includes an elapsed time after the internal combustion engine starts to operate, and wherein said limiting means comprises means for setting said allowable range to inhibit at least one, which corresponds to a richer side of the air-fuel ratio of the air-fuel mixture, of upper and lower limits of the allowable range from becoming a value in a direction to decrease said allowable range beyond a predetermined value until said elapsed time reaches a predetermined time. - View Dependent Claims (27, 28, 29, 30)
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22. An air-fuel ratio control system for an internal combustion engine, comprising:
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an exhaust gas sensor disposed downstream of a catalytic converter in an exhaust passage of the internal combustion engine, for detecting the concentration of a particular component of an exhaust gas having passed through the catalytic converter;
manipulated variable generating means for sequentially generating a manipulated variable which manipulates the air-fuel ratio of an air-fuel mixture combusted by the internal combustion engine in order to converge an output from said exhaust gas sensor to a predetermined target value; and
limiting means for limiting the manipulated variable generated by said manipulated variable generating means to a value in a predetermined allowable range, for thereby making the air-fuel ratio of the air-fuel mixture to be determined based on the manipulated variable;
said limiting means comprising means for variably setting the allowable range depending on the manipulated variable generated by said manipulated variable generating means, and means for recognizing an operating state of said internal combustion engine, and setting said allowable range depending on the recognized operating state;
wherein said exhaust gas sensor comprises an oxygen concentration sensor, and said operating state of the internal combustion engine recognized by said limiting means includes an elapsed time after the supply of fuel to the internal combustion engine is cut off, and wherein said limiting means comprises means for setting said allowable range to inhibit at least one, which corresponds to a richer side of the air-fuel ratio of the air-fuel mixture, of upper and lower limits of the allowable range from becoming a value in a direction to decrease said allowable range beyond a predetermined value until said elapsed time reaches a predetermined time.
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23. An air-fuel ratio control system for an internal combustion engine, comprising:
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an exhaust gas sensor disposed downstream of a catalytic converter in an exhaust passage of the internal combustion engine, for detecting the concentration of a particular component of an exhaust gas having passed through the catalytic converter;
manipulated variable generating means for sequentially generating a manipulated variable which manipulates the air-fuel ratio of an air-fuel mixture combusted by the internal combustion engine in order to converge an output from said exhaust gas sensor to a predetermined target value; and
limiting means for limiting the manipulated variable generated by said manipulated variable generating means to a value in a predetermined allowable range, for thereby making the air-fuel ratio of the air-fuel mixture to be determined based on the manipulated variable;
said limiting means comprising means for variably setting the allowable range depending on the manipulated variable generated by said manipulated variable generating means, and means for recognizing an operating state of said internal combustion engine, and setting said allowable range depending on the recognized operating state;
wherein said exhaust gas sensor comprises an oxygen concentration sensor, and said operating state of the internal combustion engine recognized by said limiting means includes an elapsed time after the internal combustion engine starts driving a load, and wherein said limiting means comprises means for setting said allowable range to inhibit at least one, which corresponds to a leaner side of the air-fuel ratio of the air-fuel mixture, of upper and lower limits of the allowable range from becoming a value in a direction to increase said allowable range beyond a predetermined value until said elapsed time reaches a predetermined time.
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24. An air-fuel ratio control system for an internal combustion engine, comprising:
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an exhaust gas sensor disposed downstream of a catalytic converter in an exhaust passage of the internal combustion engine, for detecting the concentration of a particular component of an exhaust gas having passed through the catalytic converter;
manipulated variable generating means for sequentially generating a manipulated variable which manipulates the air-fuel ratio of an air-fuel mixture combusted by the internal combustion engine in order to converge an output from said exhaust gas sensor to a predetermined target value; and
limiting means for limiting the manipulated variable generated by said manipulated variable generating means to a value in a predetermined allowable range, for thereby making the air-fuel ratio of the air-fuel mixture to be determined based on the manipulated variable;
said limiting means comprising means for variably setting the allowable range depending on the manipulated variable generated by said manipulated variable generating means, and means for recognizing an operating state of said internal combustion engine, and setting said allowable range depending on the recognized operating state;
wherein said operating state of the internal combustion engine recognized by said limiting means includes an idling state or an operating state other than the idling state, and wherein said limiting means comprises means for setting a predetermined range as said allowable range irrespective of the manipulated variable generated by said manipulated variable generating means if said operating state is the idling state, and variably setting said allowable range depending on the manipulated variable generated by said manipulated variable generating means if said operating state is the operating state other than the idling state.
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25. An air-fuel ratio control system for an internal combustion engine, comprising:
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an exhaust gas sensor disposed downstream of a catalytic converter in an exhaust passage of the internal combustion engine, for detecting the concentration of a particular component of an exhaust gas having passed through the catalytic converter;
manipulated variable generating means for sequentially generating a manipulated variable which manipulates the air-fuel ratio of an air-fuel mixture combusted by the internal combustion engine in order to converge an output from said exhaust gas sensor to a predetermined target value; and
limiting means for limiting the manipulated variable generated by said manipulated variable generating means to a value in a predetermined allowable range, for thereby making the air-fuel ratio of the air-fuel mixture to be determined based on the manipulated variable;
said limiting means comprising means for variably setting the allowable range depending on the manipulated variable generated by said manipulated variable generating means, and means for recognizing an operating state of said internal combustion engine, and setting said allowable range depending on the recognized operating state;
wherein said exhaust gas sensor comprises an oxygen concentration sensor, said internal combustion engine has operation modes including a normal operation mode in which the air-fuel ratio of the air-fuel mixture is manipulated based on the manipulated variable limited by said limiting means, and a lean operation mode in which the air-fuel ratio of the air-fuel mixture is manipulated into a lean air-fuel ratio irrespective of the manipulated variable, and said operating state of the internal combustion engine recognized by said limiting means includes an elapsed time from a transition from said lean operation mode to said normal operation mode, and wherein said limiting means comprises means for setting said allowable range to inhibit at least one, which corresponds to a leaner side of the air-fuel ratio of the air-fuel mixture, of upper and lower limits of the allowable range from becoming a value in a direction to increase said allowable range beyond a predetermined value until said elapsed time reaches a predetermined time. - View Dependent Claims (26)
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Specification