Failure diagnosis apparatus for evaporative fuel processing system
First Claim
1. A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system which includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in said fuel tank, an air passage connected to said canister wherein said canister communicates with the atmosphere, a first passage for connecting said canister and said fuel tank, a second passage for connecting said canister and an intake system of an internal combustion engine, a vent shut valve for opening and closing said air passage, and a purge control valve provided in said second passage, said failure diagnosis apparatus comprising:
- pressure detecting means for detecting a pressure in said evaporative fuel processing system;
engine stoppage detecting means for detecting stoppage of said engine; and
first determining means for closing said purge control valve and said vent shut valve when stoppage of said engine is detected by said engine stoppage detecting means, and for determining whether there is a leak in said evaporative fuel processing system based on a determination parameter corresponding to a second-order derivative value of the pressure detected by said pressure detecting means during a first predetermined determination period after closing of said purge control valve and said vent shut valve.
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Accused Products
Abstract
A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system. A pressure in the evaporative fuel processing system is detected, and a purge control valve and a vent shut valve are closed when stoppage of the engine is detected. A determination is made as to whether there is a leak in the evaporative fuel processing system based on the detected pressure during a predetermined determination period after closing of the purge control and vent shut valves.
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Citations
36 Claims
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1. A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system which includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in said fuel tank, an air passage connected to said canister wherein said canister communicates with the atmosphere, a first passage for connecting said canister and said fuel tank, a second passage for connecting said canister and an intake system of an internal combustion engine, a vent shut valve for opening and closing said air passage, and a purge control valve provided in said second passage, said failure diagnosis apparatus comprising:
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pressure detecting means for detecting a pressure in said evaporative fuel processing system; engine stoppage detecting means for detecting stoppage of said engine; and first determining means for closing said purge control valve and said vent shut valve when stoppage of said engine is detected by said engine stoppage detecting means, and for determining whether there is a leak in said evaporative fuel processing system based on a determination parameter corresponding to a second-order derivative value of the pressure detected by said pressure detecting means during a first predetermined determination period after closing of said purge control valve and said vent shut valve. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system which includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in said fuel tank, an air passage connected to said canister wherein said canister communicates with the atmosphere, a first passage for connecting said canister and said fuel tank, a second passage for connecting said canister and an intake system of an internal combustion engine, a vent shut valve for opening and closing said air passage, and a purge control valve provided in said second passage, said failure diagnosis apparatus comprising:
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pressure detecting means for detecting a pressure in said evaporative fuel processing system; engine stoppage detecting means for detecting stoppage of said engine; and determining means for closing said purge control valve and said vent shut valve when stoppage of said engine is detected by said engine stoppage detecting means, and for determining whether there is a leak in said evaporative fuel processing system based on a relationship between the pressure detected by said pressure detecting means and a staying time period in which the detected pressure stays at a substantially constant value, during a predetermined determination period after closing of said purge control valve and said vent shut valve. - View Dependent Claims (12)
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13. A failure diagnosis method for diagnosing a failure of an evaporative fuel processing system which includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in said fuel tank, an air passage connected to said canister wherein said canister communicates with the atmosphere, a first passage for connecting said canister and said fuel tank, a second passage for connecting said canister and an intake system of an internal combustion engine, a vent shut valve for opening and closing said air passage, and a purge control valve provided in said second passage, said failure diagnosis method comprising the steps of:
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a) detecting stoppage of said engine; b) detecting a pressure in said evaporative fuel processing system; c) closing said purge control valve and said vent shut valve when stoppage of said engine is detected; and d) determining whether there is a leak in said evaporative fuel processing system based on a determination parameter corresponding to a second-order derivative value of the detected pressure during a first predetermined determination period after closing of said purge control valve and said vent shut valve. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A failure diagnosis method for diagnosing a failure of an evaporative fuel processing system which includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in said fuel tank, an air passage connected to said canister wherein said canister communicates with the atmosphere, a first passage for connecting said canister and said fuel tank, a second passage for connecting said canister and an intake system of an internal combustion engine, a vent shut valve for opening and closing said air passage, and a purge control valve provided in said second passage, said failure diagnosis method comprising the steps of:
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a) detecting stoppage of said engine; b) detecting a pressure in said evaporative fuel processing system; c) closing said purge control valve and said vent shut valve when stoppage of said engine is detected; and d) determining whether there is a leak in said evaporative fuel processing system based on a relationship between the pressure detected by said pressure detecting means and a staying time period in which the detected pressure stays at a substantially constant value during a predetermined determination period after closing of said purge control valve and said vent shut valve. - View Dependent Claims (24)
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25. A computer program encoded on a computer readable-medium for causing a computer to carry out a failure diagnosis method for diagnosing a failure of an evaporative fuel processing system which includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in said fuel tank, an air passage connected to said canister wherein said canister communicates with the atmosphere, a first passage for connecting said canister and said fuel tank, a second passage for connecting said canister and an intake system of an internal combustion engine, a vent shut valve for opening and closing said air passage, and a purge control valve provided in said second passage, said failure diagnosis method comprising the steps of:
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a) detecting stoppage of said engine; b) detecting a pressure in said evaporative fuel processing system; c) closing said purge control valve and said vent shut valve when stoppage of said engine is detected; and d) determining whether there is a leak in said evaporative fuel processing system based on a determination parameter corresponding to a second-order derivative value of the detected pressure during a first predetermined determination period after closing of said purge control valve and said vent shut valve. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A computer program encoded on a computer readable-medium for causing a computer to carry out a failure diagnosis method for diagnosing a failure of an evaporative fuel processing system which includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in said fuel tank, an air passage connected to said canister wherein said canister communicates with the atmosphere, a first passage for connecting said canister and said fuel tank, a second passage for connecting said canister and an intake system of an internal combustion engine, a vent shut valve for opening and closing said air passage, and a purge control valve provided in said second passage, said failure diagnosis method comprising the steps of:
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a) detecting stoppage of said engine; b) detecting a pressure in said evaporative fuel processing system; c) closing said purge control valve and said vent shut valve when stoppage of said engine is detected; and d) determining whether there is a leak in said evaporative fuel processing system based on a relationship between the pressure detected by said pressure detecting means and a staying time period in which the detected pressure stays at a substantially constant value during a predetermined determination period after closing of said purge control valve and said vent shut valve. - View Dependent Claims (36)
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Specification