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 engine-powered automotive vehicle evaporative emission control, the fuel storage system including an evaporative emission space containing volatile fuel vapors generated by the volatilization of fuel in the storage system, a system detecting volatile fuel vapor leakage from the evaporative emission space, and a purge valve coupling the evaporative emission space to the engine, the purge valve regulating a flow of the volatile fuel vapors to be combusted in the engine during conditions conducive to purging, the method comprising:
- pumping gaseous fluid with respect to the evaporative emission space, the pumping including selectively operating a prime mover;
selectively operating a valve in first and second conditions, the first condition of the valve allowing the prime mover to move gaseous fluid with respect to the evaporative emission space, and the second condition of the valve disallowing the prime mover to move gaseous fluid with respect to the evaporative emission space;
sensing pressure in the evaporative emission space, the sensing including providing an electric signal controlling operation of the prime mover and of the valve;
initializing the evaporative emission space, the initializing including causing the pump to create a differential between pressure in the evaporative emission space and atmospheric pressure, and the initializing including 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;
isolating the evaporative emission space from communication with both the engine and atmosphere; and
performing the leak detection test on the evaporative emission space.
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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.
30 Citations
17 Claims
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1. A method of initializing an evaporative emission space of a fuel storage system of an engine-powered automotive vehicle evaporative emission control, the fuel storage system including an evaporative emission space containing volatile fuel vapors generated by the volatilization of fuel in the storage system, a system detecting volatile fuel vapor leakage from the evaporative emission space, and a purge valve coupling the evaporative emission space to the engine, the purge valve regulating a flow of the volatile fuel vapors to be combusted in the engine during conditions conducive to purging, the method comprising:
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pumping gaseous fluid with respect to the evaporative emission space, the pumping including selectively operating a prime mover;
selectively operating a valve in first and second conditions, the first condition of the valve allowing the prime mover to move gaseous fluid with respect to the evaporative emission space, and the second condition of the valve disallowing the prime mover to move gaseous fluid with respect to the evaporative emission space;
sensing pressure in the evaporative emission space, the sensing including providing an electric signal controlling operation of the prime mover and of the valve;
initializing the evaporative emission space, the initializing including causing the pump to create a differential between pressure in the evaporative emission space and atmospheric pressure, and the initializing including 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;
isolating the evaporative emission space from communication with both the engine and atmosphere; and
performing the leak detection test on the evaporative emission space. - View Dependent Claims (2, 3, 4, 5, 6, 7)
concluding the initializing by closing the valve and stopping the pump.
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7. The method as set forth in claim 1, wherein the initializing comprises creating a positive pressure in the evaporative emission space relative to atmospheric pressure.
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8. An evaporative emission control for an engine-powered automotive vehicle having a fuel storage system, the fuel storage system including an evaporative emission space containing volatile fuel vapors generated by the volatilization of fuel in the storage system, a system detecting volatile fuel vapor leakage from the evaporative emission space;
- and a purge valve coupling the evaporative emission space to the engine, the purge valve regulating a flow of the volatile fuel vapors to be combusted in the engine during conditions conducive to purging, the evaporative emission control comprising;
a selectively operable prime mover pumping gaseous fluid with respect to the evaporative emission space;
a selectively operable valve operating in first and second conditions, the first condition allowing the prime mover to move gaseous fluid with respect to the evaporative emission space, and the second condition disallowing the prime mover to move gaseous fluid with respect to the evaporative emission space; and
a sensor providing an electric signal related to pressure in the evaporative emission space, the electric signal controlling operation of the prime mover and of the valve;
wherein the leak detection system initializes the evaporative emission space preparatory to performing a leak detection test, the initializing including causing the pump to create a differential between pressure in the evaporative emission space and atmospheric pressure sufficient to perform a leak detection test, and the initializing including 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. - View Dependent Claims (9, 10, 11, 12, 13, 14)
- and a purge valve coupling the evaporative emission space to the engine, the purge valve regulating a flow of the volatile fuel vapors to be combusted in the engine during conditions conducive to purging, the evaporative emission control comprising;
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15. A method of performing a leak detection test on an evaporative emission space of a fuel storage system of an engine-powered automotive vehicle evaporative emission control, the fuel storage system including an evaporative emission space containing volatile fuel vapors generated by the volatilization of fuel in the storage system, a system detecting volatile fuel vapor leakage from the evaporative emission space, and a purge valve coupling the evaporative emission space to the engine, the purge valve regulating a flow of the volatile fuel vapors to be combusted in the engine during conditions conductive to purging, the method comprising:
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initializing the evaporative emission space, the initializing including;
creating a differential between pressure in the evaporative emission space and atmospheric pressure, and alternately increasing the created pressure differential above a nominal pressure differential and decreasing the creating pressure differential below the nominal pressure differential, a plurality of cycles over time, within a range of differential pressures sufficient to operate the system detecting volatile fuel vapor leakage; and
isolating the evaporative emission space from communication with both the engine and atmosphere. - View Dependent Claims (16, 17)
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Specification