Initialization method for an automotive evaporative emission leak detection system
First Claim
1. A method of initializing an evaporative emission space of a fuel storage system of an automotive vehicle preparatory to performing a leak detection test on the evaporative emission space, the vehicle being powered by a fuel-consuming engine and including an evaporative emission control system for purging fuel vapor from the evaporative emission space to the engine for combustion therein during conditions conducive to purging, the method comprising:
- creating a differential between pressure in the evaporative emission space and, atmospheric pressure sufficient to perform a leak detection test;
alternately increasing the created pressure differential above a nominal pressure differential and decreasing the created pressure differential below the nominal pressure differential, a plurality of cycles over time, within a range of differential pressures sufficient to perform a leak detection test; and
then isolating the evaporative emission space from communication with both the engine and atmosphere, and performing a leak detection test.
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Abstract
An on-board evaporative emission leak detection system and method that detects leakage from an evaporative emission space of a fuel system of an automotive vehicle. A test includes an initialization, or stabilization, phase during which a differential between pressure in the evaporative emission space and atmospheric pressure is created, and then varied, over time, within a range of differential pressures suitable for performing a leak detection test. This varying of pressure differential alternately increases the created pressure differential above a nominal pressure differential and decreases the created pressure differential below the nominal pressure differential. The leak detection test is then performed.
23 Citations
10 Claims
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1. A method of initializing an evaporative emission space of a fuel storage system of an automotive vehicle preparatory to performing a leak detection test on the evaporative emission space, the vehicle being powered by a fuel-consuming engine and including an evaporative emission control system for purging fuel vapor from the evaporative emission space to the engine for combustion therein during conditions conducive to purging, the method comprising:
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creating a differential between pressure in the evaporative emission space and, atmospheric pressure sufficient to perform a leak detection test;
alternately increasing the created pressure differential above a nominal pressure differential and decreasing the created pressure differential below the nominal pressure differential, a plurality of cycles over time, within a range of differential pressures sufficient to perform a leak detection test; and
thenisolating the evaporative emission space from communication with both the engine and atmosphere, and performing a leak detection test. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of evaluating system integrity of an evaporative emission system in fluid communication with an engine and with atmosphere, the method comprising:
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pressurizing the evaporative emission system above atmospheric pressure;
alternately increasing and decreasing, a plurality of cycles, pressure in the evaporative emission system within a range around a nominal pressure value above atmospheric pressure;
eliminating the fluid communication of the evaporative emission system with the engine and atmosphere; and
performing a leak detection test on the evaporative emission system.
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Specification