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METHOD TO CONTROL FUEL VAPOR FLOW INTO CANISTER DURING REFUELING FOR HEV’S

IP.com Disclosure Number: IPCOM000234787D
Publication Date: 2014-Feb-05
Document File: 1 page(s) / 235K

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METHOD TO CONTROL FUEL VAPOR FLOW INTO CANISTER DURING REFUELING FOR HEV'S

Vehicles sold in North America and other markets contain a carbon canister that adsorbs refueling (North America only), diurnal and running loss vapors. Carbon canister is sized based on the tank capacity and canister load rate at maximum fuel dispense rates (e.g. 10GPM). During the first few seconds of a fuel dispense, a considerable pressure spike results in the tank. The initial peak pressure generates more vapor content and the carbon canister's ability to adsorb hydrocarbon may be compromised. The carbon canister's ability to adsorb hydrocarbons is enhanced at low flow rates.The vapor load capacity can vary based on noise factors such as external environmental temperature (system skin temperature), fuel dispense temperature, nozzle type and dispense flow rate. Fuel dispensing temperature, flow rate or external system environment are not controllable, however the fuel tank pressure can be monitored to minimize variation in canister loading rate by controlling the vapor flow into the canister.

Method

We monitor fuel tank pressure during refueling events, illustrated below with a pressure transducer. During refueling, the PCM monitors this signal and controls the mass vapor flow going into the carbon canister by sending a PWM signal to the flow control valve located between the fuel tank and the canister. Hence, this strategy in turn influences the canister loading during the refueling...