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US 5,845,489 AGranted
Abnormality detector for air-fuel ratio control system
AssigneeDenso Corporation
InventorsHisayo Dohta, Shigenori Isomura, Katsuhiko Kawai
Life of this patent
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Abstract
An inflow quantity of an exhaust gas component flowing into a catalyst is calculated based upon air fuel ratio detected by an upstream air fuel ratio sensor which is provided on the upstream side of the catalyst. In addition, an outflow quantity of an exhaust gas component flowing out of the catalyst is calculated based upon air fuel ratio detected by a downstream air fuel ratio sensor which is provided on the downstream side of the catalyst. The quantity of an exhaust gas component absorbed by the catalyst can be detected in real time based upon a difference between the inflow quantity and outflow quantity. Thus, a state of the catalyst can be precisely detected in real time.
Claims35
An abnormality detector for an air-fuel ratio control system, said detector comprising:
- inflow calculating means for calculating an inflow quantity of an exhaust gas component flowing into a catalyst based on output signal from an air-fuel ratio sensor which detects an air fuel ratio of exhaust gas and a load condition applied to an engine when a current air fuel ratio of exhaust gas on an upstream side of said catalyst deviates from a theoretical air fuel ratio;
- outflow calculating means for calculating an outflow quantity of an exhaust gas component flowing out of said catalyst based on output signal from an air-fuel ratio sensor which detects an air fuel ratio of exhaust gas and a load condition applied to an engine when a current air fuel ratio of exhaust gas on a downstream side of said catalyst deviates from a theoretical air fuel ratio;
- and
- catalyst state detecting means for detecting a state of said catalyst based upon the result of calculations made by said inflow calculating means and said outflow calculating means.
1 more element
An abnormality detector for an air-fuel ratio control system, said detector comprising:
- inflow calculating means for calculating an inflow quantity of an exhaust gas component flowing into a catalyst when a current air fuel ratio of exhaust gas on an upstream side of said catalyst deviates from a theoretical air fuel ratio;
- outflow calculating means for calculating an outflow quantity of an exhaust gas component flowing out of said catalyst when a current air fuel ratio of exhaust gas on a downstream side of said catalyst deviates from a theoretical air fuel ratio;
- and
- catalyst state detecting means for detecting a state of said catalyst based upon the result of calculations made by said inflow calculating means and said outflow calculating means;
- wherein said catalyst state detecting means includes means for deriving a current quantity of said exhaust gas component absorbed by said catalyst by subtracting said outflow quantity of said exhaust gas component from said inflow quantity of said exhaust gas component when an absolute value of said outflow quantity of said exhaust gas component is smaller than a predetermined value.
2 more elements
An abnormality detector for an air-fuel ratio control system, said detector comprising:
- inflow calculating means for calculating an inflow quantity of an exhaust gas component flowing into a catalyst when a current air fuel ratio of exhaust gas on an upstream side of said catalyst deviates from a theoretical air fuel ratio;
- outflow calculating means for calculating an outflow quantity of an exhaust gas component flowing out of said catalyst when a current air fuel ratio of exhaust gas on a downstream side of said catalyst deviates from a theoretical air fuel ratio;
- and
- catalyst state detecting means for detecting a state of said catalyst based upon the result of calculations made by said inflow calculating means and said outflow calculating means;
- wherein said catalyst state detecting means includes means for deriving a maximum quantity of said exhaust gas component absorbed by said catalyst by subtracting said outflow quantity of said exhaust gas component from said inflow quantity of said exhaust gas component when an absolute value of said outflow quantity of said exhaust gas component is equal to or greater than a predetermined value.
2 more elements
An abnormality detector for an air-fuel ratio control system, said detector comprising:
- inflow calculating means for calculating an inflow quantity of an exhaust gas component flowing into a catalyst when a current air fuel ratio of exhaust gas on an upstream side of said catalyst deviates from a theoretical air fuel ratio;
- outflow calculating means for calculating an outflow quantity of an exhaust gas component flowing out of said catalyst when a current air fuel ratio of exhaust gas on a downstream side of said catalyst deviates from a theoretical air fuel ratio;
- and
- catalyst state detecting means for detecting a state of said catalyst based upon the result of calculations made by said inflow calculating means and said outflow calculating means;
- wherein:
- said catalyst state detecting means includes:
- current quantity deriving means for deriving a current quantity of said exhaust gas component absorbed by said catalyst by subtracting said outflow quantity of said exhaust gas component from said inflow quantity of said exhaust gas component when an absolute value of said outflow quantity of said exhaust gas component is smaller than a predetermined value;
- maximum quantity deriving means for deriving a maximum quantity of said exhaust gas component absorbed by said catalyst by subtracting said outflow quantity of said exhaust gas component from said inflow quantity of said exhaust gas component when an absolute value of said outflow quantity of said exhaust gas component is equal to or greater than a predetermined value;
- and
- catalyst deterioration detecting means for detecting a degree of deterioration of said catalyst by comparing said maximum quantity of said exhaust gas component absorbed by said catalyst with a maximum quantity of said exhaust gas component absorbed by said catalyst when said catalyst does not deteriorate.
7 more elements
An abnormality detector for an air-fuel ratio control system, said detector comprising:
- inflow calculating means for calculating an inflow quantity of an exhaust gas component flowing into a catalyst when a current air fuel ratio of exhaust gas on an upstream side of said catalyst deviates from a theoretical air fuel ratio;
- outflow calculating means for calculating an outflow quantity of an exhaust gas component flowing out of said catalyst when a current air fuel ratio of exhaust gas on a downstream side of said catalyst deviates from a theoretical air fuel ratio;
- and
- catalyst state detecting means for detecting a state of said catalyst based upon the result of calculations made by said inflow calculating means and said outflow calculating means;
- wherein:
- said catalyst state detecting means includes:
- period setting means for setting a deterioration determining period during which deterioration of said catalyst is determined;
- and
- catalyst deterioration detecting means for detecting deterioration of said catalyst based upon a total inflow quantity and a total outflow quantity of said exhaust gas component during said deterioration determining period set by said period setting means;
- and
- said catalyst state detecting means includes:
- saturation frequency counting means for counting a frequency in which said catalyst is saturated with lean/rich component during said deterioration determining period;
- maximum quantity average value calculating means for calculating an average value of a maximum quantity of said lean/rich component of said exhaust gas absorbed by said catalyst by dividing a maximum quantity obtained by subtracting a total outflow quantity of said lean/rich component from a total inflow quantity of said lean/rich component during said deterioration determining period by said frequency in which said catalyst is saturated, counted by said saturation frequency counting means;
- and
- catalyst deterioration detecting means for detecting a degree of deterioration of said catalyst based upon said average value of said maximum quantity of said lean/rich component absorbed by said catalyst.
12 more elements
An abnormality detector for an air-fuel ratio control system, comprising:
- a catalyst provided in an exhaust pipe of an engine for purifying exhaust gas exhausted from said engine;
- an upstream air fuel ratio sensor for detecting air fuel ratio on an upstream side of said catalyst;
- a downstream air fuel ratio sensor for detecting air fuel ratio on a downstream side of said catalyst;
- inflow calculating means for calculating an inflow quantity of an exhaust gas component flowing into said catalyst based upon an output of said upstream air fuel ratio sensor and a load condition applied to said engine;
- outflow calculating means for calculating an outflow quantity of an exhaust gas component flowing out of said catalyst based upon an output of said downstream air fuel ratio sensor and a load condition applied to said engine;
- and
- catalyst state detecting means for detecting a state of said catalyst based upon said inflow quantity of said exhaust gas component and said outflow quantity of said exhaust gas component calculated by said inflow calculating means and said outflow calculating means.
4 more elements
An abnormality detector for an air-fuel ratio control system, said detector comprising:
- a catalyst provided in an exhaust pipe of an engine for purifying exhaust gas exhausted from said engine;
- an upstream air fuel ratio sensor for detecting air fuel ratio on an upstream side of said catalyst;
- a downstream air fuel ratio sensor for detecting air fuel ratio on a downstream side of said catalyst;
- inflow calculating means for calculating inflow quantity of an exhaust gas component flowing into said catalyst based upon an output of said upstream air fuel ratio sensor;
- outflow calculating means for calculating an outflow quantity of an exhaust gas component flowing out of said catalyst based upon an output of said downstream air fuel ratio sensor;
- and
- catalyst state detecting means for detecting a state of said catalyst based upon said inflow quantity of said exhaust gas component and said outflow quantity of said exhaust gas component calculated by said inflow calculating means and said outflow calculating means;
- wherein:
- said downstream air fuel ratio sensor has output characteristics in which its output signal varies linearly according to air fuel ratio of exhaust gas while an operating voltage is applied thereto and its output is inverted depending upon air fuel ratio being rich or lean while said operating voltage is not applied;
- said outflow calculating means calculates said outflow quantity of said exhaust gas component flowing out of said catalyst based upon a difference between an air fuel ratio detected by said downstream air fuel sensor and a central value of air fuel ratios detected by said downstream air fuel ratio when said engine is operated in a steady state and a load condition applied to said engine;
- and
- determining means for determining whether said central value of air fuel ratio is to be calculated based upon an output of said downstream air fuel ratio sensor when said operating voltage is not applied to said downstream air fuel ratio sensor.
9 more elements
An abnormality detector for an air-fuel ratio control system, said detector comprising:
- a catalyst provided in an exhaust pipe of an engine for purifying exhaust gas exhausted from said engine;
- an upstream air fuel ratio sensor for detecting air fuel ratio on an upstream side of said catalyst;
- a downstream air fuel ratio sensor for detecting air fuel ratio on a downstream side of said catalyst;
- inflow calculating means for calculating inflow quantity of an exhaust gas component flowing into said catalyst based upon an output of said upstream air fuel ratio sensor;
- outflow calculating means for calculating an outflow quantity of an exhaust gas component flowing out of said catalyst based upon an output of said downstream air fuel ratio sensor;
- and
- catalyst state detecting means for detecting a state of said catalyst based upon said inflow quantity of said exhaust gas component and said outflow quantity of said exhaust gas component calculated by said inflow calculating means and said outflow calculating means;
- wherein said downstream air fuel ratio sensor is an oxygen sensor an output voltage of which inverts depending upon air fuel ratio of exhaust gas being rich or lean, and further comprising:
- output linearizing means for converting said output voltage of said oxygen sensor into air fuel ratio by linearizing said output voltage.
6 more elements
An abnormality detector for an air-fuel ratio control system, said detector comprising:
- inflow calculating means for calculating an inflow quantity of an exhaust gas component flowing into a catalyst when a current air fuel ratio of exhaust gas on an upstream side of said catalyst deviates from a theoretical air fuel ratio;
- outflow calculating means for calculating an outflow quantity of an exhaust gas component flowing out of said catalyst when a current air fuel ratio of exhaust gas on a downstream side of said catalyst deviates from a theoretical air fuel ratio;
- and
- catalyst state detecting means for detecting a state of said catalyst based upon the result of calculations made by said inflow calculating means and said outflow calculating means;
- upstream and downstream air fuel ratio sensors respectively installed on an upstream side and on a downstream side of a catalyst provided in an exhaust pipe of an engine to purify exhaust gas;
- means for calculating a central value of air fuel ratio on the upstream side of said catalyst based upon an output of said upstream air fuel ratio sensor;
- means for calculating a central value of air fuel ratio on the downstream side of said catalyst based upon an output of said downstream air fuel ratio sensor;
- means for calculating an error between said central value of air fuel ratio on the upstream side of said catalyst and said central value of air fuel ratio on the downstream side of said catalyst;
- and
- sensor abnormality determining means for determining an abnormality of said upstream air fuel ratio sensor or said downstream air fuel ratio sensor based upon whether said error is in a predetermined range.
7 more elements
An abnormality detector for an air-fuel ratio control system in which upstream and downstream air fuel ratio sensors are respectively installed on an upstream side and on a downstream side of a catalyst provided in an exhaust pipe of an engine to purify exhaust gas, comprising:
- means for calculating a central value of air fuel ratio on the upstream side of said catalyst based upon an output of said upstream air fuel ratio sensor;
- means for calculating a central value of air fuel ratio on the downstream side of said catalyst based upon an output of said downstream air fuel ratio sensor;
- means for calculating an error between said central value of air fuel ratio on the upstream side of said catalyst and said central value of air fuel ratio on the downstream side of said catalyst;
- and
- sensor abnormality determining means for determining an abnormality of said upstream air fuel ratio sensor or said downstream air fuel ratio sensor based upon whether said error is in a predetermined range.
2 more elements
Dependencies are inferred from the claim text.