초록 ▼

A method and apparatus for detecting leakage from an evaporative emission space (14, 18) of a vehicle fuel system by utilizing naturally occurring vacuum that can occur under certain favorable conditions after a fuel-consuming engine (12) that powers an automotive vehicle has been turned off. If the

A method and apparatus for detecting leakage from an evaporative emission space (14, 18) of a vehicle fuel system by utilizing naturally occurring vacuum that can occur under certain favorable conditions after a fuel-consuming engine (12) that powers an automotive vehicle has been turned off. If there is no leakage, vapor pressure in the fuel system will begin to decrease. If it is assumed that the vapor pressure was approximately atmospheric when the engine was turned off, and that no leakage existed, ensuing cooling will create increasing vacuum in headspace of the fuel tank as the temperature drops. In the absence of leakage, a well-defined relationship exists. Measurements of physical parameters (24, 26) characterizing fluid conditions in the fuel tank are taken as cooling proceeds and processed. Results are evaluated to obtain leakage information.

대표청구항 ▼

[ What is claimed is:] [1.] A method for detecting leakage from an evaporative emission space of an automotive vehicle fuel system that includes a tank for holding volatile liquid fuel, the method comprising:sensing each of plural physical parameters characterizing a gas mixture that includes volati

[ What is claimed is:] [1.] A method for detecting leakage from an evaporative emission space of an automotive vehicle fuel system that includes a tank for holding volatile liquid fuel, the method comprising:sensing each of plural physical parameters characterizing a gas mixture that includes volatized fuel, in the evaporative emission space;measuring a beginning value of a first of the sensed parameters at a beginning value of a second of the sensed parameters at a beginning test time;measuring an ending value of the first parameter at an ending value of the second parameter at an ending test time;deriving an actual measurement by processing the beginning and the ending values of the first parameter and the beginning and ending test times using a relationship that correlates difference between the beginning and ending values of the first parameter, difference between the beginning and the ending test times, and difference between the beginning and the ending values of the second parameter;deriving a theoretical measurement that represents the value of an actual measurement resulting from the step of deriving the actual measurement in the absence of leakage from the evaporative emission space; andcomparing the derived actual measurement to the derived theoretical measurement.