Apparatus and method for diagnosing faults of fuel vapor treatment unit
First Claim
1. A method of diagnosing faults of a fuel vapor treatment unit which temporarily adsorbs fuel vapor from a fuel tank of an internal combustion engine into an adsorption unit via a vapor passage, and then processes the fuel vapor by drawing this into an engine intake system from said adsorption unit under predetermined engine operating conditions, via a purge passage in which is disposed a purge control valve, comprising:
- detecting if said engine is in a condition for close to start time;
permitting diagnosis for the presence of a fault of said fuel vapor treatment unit on the proviso that a condition for close to engine start time is detected, closing said purge control valve, and supplying pressurized air to the inside of said fuel vapor treatment unit when said diagnosis is permitted, detecting a pressure condition inside said fuel vapor treatment unit after supplying said pressurized air, and diagnosing the presence of a fault of said fuel vapor treatment unit based on said detected pressure condition.
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Accused Products
Abstract
In an apparatus and method where the interior of a fuel vapor treatment unit of an internal combustion engine is closed off and pressurized air is supplied, so that the presence of a leak of fuel vapor is diagnosed based on a change condition of the pressure inside the fuel vapor treatment unit, the construction is such that the diagnosis is permitted on the proviso that a condition for close to engine start time is detected. As a result, the influence of heat from the engine after the engine has stopped, and the influence of vibration due to the road surface when the vehicle is travelling and of atmospheric pressure changes due to differences in altitude can be simultaneously avoided, so that erroneous diagnosis due to these influences can be prevented, and fault diagnosis accuracy thus improved.
29 Citations
23 Claims
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1. A method of diagnosing faults of a fuel vapor treatment unit which temporarily adsorbs fuel vapor from a fuel tank of an internal combustion engine into an adsorption unit via a vapor passage, and then processes the fuel vapor by drawing this into an engine intake system from said adsorption unit under predetermined engine operating conditions, via a purge passage in which is disposed a purge control valve, comprising:
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detecting if said engine is in a condition for close to start time;
permitting diagnosis for the presence of a fault of said fuel vapor treatment unit on the proviso that a condition for close to engine start time is detected, closing said purge control valve, and supplying pressurized air to the inside of said fuel vapor treatment unit when said diagnosis is permitted, detecting a pressure condition inside said fuel vapor treatment unit after supplying said pressurized air, and diagnosing the presence of a fault of said fuel vapor treatment unit based on said detected pressure condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus for diagnosing faults of a fuel vapor treatment unit comprising:
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said fuel vapor treatment unit which temporarily adsorbs fuel vapor from a fuel tank of an internal combustion engine into an adsorption unit via a vapor passage, and then processes the fuel vapor by drawing this into an engine intake system from said adsorption unit under predetermined engine operating conditions, via a purge passage in which is disposed a purge control valve;
a pump device for supplying pressurized air to the inside of said fuel vapor treatment unit;
a pressure condition detection device for detecting a pressure condition inside said fuel vapor treatment unit;
a start time vicinity detection device for detecting a condition for close to engine start time;
a fault diagnosis permit device for permitting fault diagnosis of said fuel vapor treatment unit on the proviso that conditions for close to engine start time are detected by said start time vicinity detection device; and
a fault diagnosis device for closing said purge control valve, and supplying pressurized air to the inside of said fuel vapor treatment unit by said pump device when said diagnosis is permitted by said fault diagnosis permit device, to raise the pressure inside said fuel vapor treatment unit, and then diagnosing the presence of a fault of said fuel vapor treatment unit based on a pressure condition inside said fuel vapor treatment unit detected by said pressure condition detection device. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. An apparatus for diagnosing faults of a fuel vapor treatment unit comprising:
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said fuel vapor treatment unit which temporarily adsorbs fuel vapor from a fuel tank of an internal combustion engine into an adsorption unit via a vapor passage, and then processes the fuel vapor by drawing this into an engine intake system from said adsorption unit under predetermined engine operating conditions, via a purge passage in which is disposed a purge control valve;
pressurized air supply means for supplying pressurized air to the inside of said fuel vapor treatment unit;
pressure condition detection means for detecting a pressure condition inside said fuel vapor treatment unit;
start time vicinity detection means for detecting a condition for close to engine start time;
fault diagnosis permit means for permitting fault diagnosis of said fuel vapor treatment unit on the proviso that conditions for close to engine start time are detected by said start time vicinity detection means; and
fault diagnosis means for closing said purge control valve, and supplying pressurized air to the inside of said fuel vapor treatment unit by said pressurized air supply means when said diagnosis is permitted by said fault diagnosis permit means, to raise the pressure inside said fuel vapor treatment unit, and then diagnosing the presence of a fault of said fuel vapor treatment unit based on a pressure condition inside said fuel vapor treatment unit detected by said pressure condition detection means.
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Specification