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 and communicating said canister 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;
negative pressure reserving means for reserving negative pressure in said intake system during operation of said engine;
engine stoppage detecting means for detecting stoppage of said engine;
negative pressure introducing means for closing said purge control valve and said vent shut valve to introduce the negative pressure reserved in said negative pressure reserving means into said evaporative fuel processing system, when stoppage of said engine is detected by said engine stoppage detecting means; and
determining means for determining whether or not there is a leak in said evaporative fuel processing system, based on the pressure detected by said pressure detecting means during a predetermined determination period after the negative pressure is introduced into said evaporative fuel processing system.
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Accused Products
Abstract
A failure diagnosis apparatus for diagnosing a failure of an evaporative fuel processing system. The system includes a fuel tank, a canister having adsorbent for adsorbing evaporative fuel generated in the fuel tank, an air passage connected to the canister and communicating the canister with the atmosphere, a first passage for connecting the canister and the fuel tank, a second passage for connecting the canister and an intake system of an internal combustion engine, a vent shut valve for opening and closing the air passage, and a purge control valve provided in the second passage. A pressure in the evaporative fuel processing system is detected. Negative pressure in the intake system is reserved in a negative pressure reservoir during operation of the engine. The purge control valve and the vent shut valve are closed to introduce the reserved negative pressure into the evaporative fuel processing system, when stoppage of the engine is detected. It is determined whether or not there is a leak in the evaporative fuel processing system, based on the pressure detected during a predetermined determination period after introduction of the negative pressure.
31 Citations
15 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 and communicating said canister 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;
negative pressure reserving means for reserving negative pressure in said intake system during operation of said engine;
engine stoppage detecting means for detecting stoppage of said engine;
negative pressure introducing means for closing said purge control valve and said vent shut valve to introduce the negative pressure reserved in said negative pressure reserving means into said evaporative fuel processing system, when stoppage of said engine is detected by said engine stoppage detecting means; and
determining means for determining whether or not there is a leak in said evaporative fuel processing system, based on the pressure detected by said pressure detecting means during a predetermined determination period after the negative pressure is introduced into said evaporative fuel processing system. - View Dependent Claims (2, 3, 4, 5)
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6. 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 and communicating said canister 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) reserving negative pressure in said intake system during operation of said engine;
b) detecting stoppage of said engine;
c) closing said purge control valve and said vent shut valve to introduce the reserved negative pressure into said evaporative fuel processing system, when stoppage of said engine is detected;
d) detecting a pressure in said evaporative fuel processing system; and
e) determining whether or not there is a leak in said evaporative fuel processing system, based on the detected pressure during a predetermined determination period after the negative pressure is introduced into said evaporative fuel processing system. - View Dependent Claims (7, 8, 9, 10)
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11. A computer program 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 and communicating said canister 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) reserving negative pressure in said intake system during operation of said engine;
b) detecting stoppage of said engine;
c) closing said purge control valve and said vent shut valve to introduce the reserved negative pressure into said evaporative fuel processing system, when stoppage of said engine is detected;
d) detecting a pressure in said evaporative fuel processing system; and
e) determining whether or not there is a leak in said evaporative fuel processing system, based on the detected pressure during a predetermined determination period after the negative pressure is introduced into said evaporative fuel processing system. - View Dependent Claims (12, 13, 14, 15)
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Specification