Patent ID: 7882824

Claim:
A method for recovering vapor during an onboard refueling operation, comprising the steps of: providing a flow path between a fuel tank and a purge canister; providing a fuel level sensor that indicates a level of fuel in the fuel tank, a vapor pressure sensor that indicates a pressure of fuel vapor in the fuel tank, and a refueling event indicator; providing an electronic valve in said flow path, which is actuated in response to signals received from the fuel level sensor, the vapor pressure sensor, and the refueling event indicator; actuating the electronic valve to open the flow path when a start of a refueling event is detected; monitoring a level value received from the fuel level sensor when the flow path is open; actuating the electronic valve to close the flow path when the level value reaches a predetermined fuel level; monitoring a pressure value received from the vapor pressure sensor when the flow path is closed; and actuating the electronic valve to cyclically open and close the flow path depending on the pressure value until a determination is made that the refueling event is finished on the basis of the monitored pressure value, wherein said actuating of the electronic valve to open and close the flow path depending on the pressure value comprises the steps of: measuring and storing a pressure value received from the vapor pressure sensor; determining a peak pressure value by comparing the measured pressure value to a previously stored pressure value; storing the peak pressure value; monitoring the pressure value received from the vapor pressure sensor until the pressure value decays to a predetermined percentage of the peak pressure value; and actuating the electronic valve to open the flow path for a predetermined length of time if and when the pressure value decays to a predetermined percentage of the peak pressure value, then actuating the electronic valve to close the flow path.