Fuel vapor treatment system for internal combustion engine
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Abstract
A pump generates a gas flow within a measurement passage having an orifice. A differential pressure sensor detects a pressure difference between both ends of the orifice. Switching valves are disposed in the measurement passage to create a first concentration measurement state in which the measurement passage is opened at both ends thereof and the gas flowing through the measurement passage is the atmosphere, and a second concentration measurement state in which the measurement passage is in communication at both ends thereof with a canister and the gas flowing through the measurement passage is a fuel vapor-containing air-fuel mixture provided from the canister. An ECU calculates a fuel vapor concentration by based on a pressure difference detected in the first concentration measurement state and a pressure difference detected in the second concentration measurement state.
67 Citations
49 Claims
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1-19. -19. (canceled)
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20. A fuel vapor treatment system for an internal combustion engine comprising:
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a canister containing an adsorbing material for temporarily adsorbing fuel vapor conducted thereto from the interior of a fuel tank through an inlet passage;
a purging passage for conducting an air-fuel mixture containing fuel vapor desorbed from the adsorbing material into an intake pipe of the internal combustion engine and purging the fuel vapor;
a purge control valve disposed in the purging passage;
a fuel vapor passage for connecting the canister with an atmosphere;
a gas flow producing means provided in the fuel vapor passage for producing a gas flow; and
a pressure detecting means provided in the fuel vapor passage for detecting pressure in the fuel vapor passage, wherein a purge flow rate is adjusted based on the pressure in the fuel vapor passage detected by the pressure detecting means in a state where the gas flow is produced by the gas flow producing means. - View Dependent Claims (21)
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22. A fuel vapor treatment system for an internal combustion engine comprising:
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a canister containing an adsorbing material for temporarily adsorbing fuel vapor conducted thereto from the interior of a fuel tank through an inlet passage;
a purging passage for conducting an air-fuel mixture containing fuel vapor desorbed from the adsorbing material into an intake pipe of the internal combustion engine and purging the fuel vapor;
a purge control valve disposed in the purging passage;
a measurement passage having an orifice;
a gas flow producing means for producing a gas flow within and along the measurement passage;
a measurement passage switching means for switching the measurement passage between a first measurement state in which the measurement passage is open to the atmosphere at both ends thereof, allowing an air to flow through the measurement passage, and a second measurement state in which the measurement passage is put in communication at least one end thereof with the canister, allowing the air-fuel mixture fed from the canister to flow through the measurement passage; and
a pressure detecting means for detecting a pressure depending on the orifice and the gas flow producing means, wherein a purge flow rate is adjusted based on a pressure detected in the first measurement state and a pressure detected in the second measurement state. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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Specification