DIAGNOSTIC STRATEGY FOR A FUEL VAPOR CONTROL SYSTEM
First Claim
1. A method for operating a fuel vapor control system included in a vehicle having an engine, comprising:
- storing positive or negative pressure in fuel tank while isolated from an evaporation canister region;
transferring at least a portion of the stored pressure to the canister region; and
indicating degradation of the evaporation canister region based on a response of the transferred pressure in the canister region while the canister region is isolated from the fuel tank.
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Abstract
A method for operating a fuel vapor control system included in a vehicle having an internal combustion engine is provided. The method may include storing positive pressure or negative pressure in an isolated fuel tank, transferring at least a portion of the positive pressure or the negative pressure to an evaporation canister region, and determining degradation of the evaporation canister based on a pressure response of the evaporation canister region while the evaporation canister region is isolated from the fuel tank. In this way, it is possible to utilize pressure that may be passively generated in one portion of the system, even during shut-down engine operation, to verify the integrity of another portion of the system.
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Citations
19 Claims
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1. A method for operating a fuel vapor control system included in a vehicle having an engine, comprising:
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storing positive or negative pressure in fuel tank while isolated from an evaporation canister region; transferring at least a portion of the stored pressure to the canister region; and indicating degradation of the evaporation canister region based on a response of the transferred pressure in the canister region while the canister region is isolated from the fuel tank. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for operating a fuel vapor control system included in a vehicle having an internal combustion engine, the method comprising:
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fluidically isolating a fuel tank from the atmosphere and external components; if the pressure differential between a fuel tank pressure and an atmospheric pressure is greater than a first threshold value, providing fluidic communication between an evaporation canister region and the fuel tank; fluidically isolating the evaporation canister region from the atmosphere and external components after providing the fluidic communication; and if the time rate of change of a pressure within the isolated evaporation canister region exceeds a second threshold value, implementing an evaporation canister default mode. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A fuel vapor control system for a vehicle including an internal combustion engine, the system comprising:
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an atmospheric pressure sensor electronically coupled to a controller; a fuel tank including a fuel tank pressure sensor electronically coupled to the controller; an evaporation canister fluidly coupled to the fuel tank, the internal combustion engine, and a surrounding atmosphere; a pressure sensor coupled within an evaporation canister region and electronically coupled to the controller; a control system including the controller having code executable via a processor to; fluidically isolate the fuel tank from the surrounding atmosphere and external components; provide fluidic communication between the fuel tank and the evaporation canister region when a pressure differential between the fuel tank and the atmospheric exceeds a first threshold value after the fuel tank is fluidically isolated; fluidically isolate an evaporation canister region from the surrounding atmosphere and external components after fluidic communication is provided between the fuel tank and the evaporation canister; and implement a default mode when the time rate of change of a pressure exceeds a second threshold value and/or a pressure differential within the evaporation canister region exceeds a third threshold value. - View Dependent Claims (16, 17, 18, 19)
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Specification