Automotive evaporative emission leak detection system and method
First Claim
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1. A leak detection test method for an evaporative emission space of a fuel storage system of an automotive vehicle comprising:
- creating a differential between pressure in an evaporative emission space and atmospheric pressure sufficient to perform a leak detection test on the evaporative emission space;
isolating the evaporative emission space so that reduction in the created differential is indicative of leakage from the evaporative emission space, and starting a timer to measure time;
defining a time limit for the timer;
as the timer times, sensing the differential between pressure in the evaporative emission space and atmospheric pressure; and
when the timer times to the defined time limit, selectively reducing the differential between pressure in the evaporative emission space and atmospheric pressure, and measuring a parameter related to the selective reduction of the differential between pressure in the evaporative emission space and atmospheric pressure.
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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. A leak size measurement is then obtained using an algorithm.
36 Citations
25 Claims
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1. A leak detection test method for an evaporative emission space of a fuel storage system of an automotive vehicle comprising:
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creating a differential between pressure in an evaporative emission space and atmospheric pressure sufficient to perform a leak detection test on the evaporative emission space; isolating the evaporative emission space so that reduction in the created differential is indicative of leakage from the evaporative emission space, and starting a timer to measure time; defining a time limit for the timer; as the timer times, sensing the differential between pressure in the evaporative emission space and atmospheric pressure; and when the timer times to the defined time limit, selectively reducing the differential between pressure in the evaporative emission space and atmospheric pressure, and measuring a parameter related to the selective reduction of the differential between pressure in the evaporative emission space and atmospheric pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A leak detection test method for an evaporative emission space of a fuel storage system of an automotive vehicle comprising:
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creating a differential between pressure in an evaporative emission space and atmospheric pressure sufficient to perform a leak detection test on the evaporative emission space; isolating the evaporative emission space so that reduction in the created differential is indicative of leakage from the evaporative emission space, and starting a timer to measure time; defining a time limit for the timer; defining a differential less than the created differential; as the timer times, sensing the differential between pressure in the evaporative emission space and atmospheric pressure; when the sensed differential between pressure in the evaporative emission space and atmospheric pressure reaches the defined differential before the measure of time on the timer has reached the defined time limit, utilizing the measure of time that is present on the timer when the sensed differential between pressure in the evaporative emission space and atmospheric pressure reaches the defined differential as a factor for determining leakage from the evaporative emission space; and when the measure of time on the timer reaches the defined time limit before the sensed differential between pressure in the evaporative emission space and atmospheric pressure has reached the defined differential, selectively reducing the differential between pressure in the evaporative emission space and atmospheric pressure, measuring a parameter related to the selective reduction of the differential between pressure in the evaporative emission space and atmospheric pressure, and utilizing the parameter measurement as a factor for determining leakage from the evaporative emission space. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A leak detection system for detecting leakage from an evaporative emission space of a fuel storage system that stores volatile liquid fuel for a fuel-consuming engine of an automotive vehicle, including an evaporative emission control having an atmospheric vent path containing a vent valve for venting the evaporative emission space to atmosphere and a vapor purge path for purging fuel vapors from the evaporative emission space to the engine under conditions conducive to purging, the system comprising:
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a timer to measure time; a time limit setting device for setting a defined time limit for the timer; a sensor for sensing the differential between pressure in the evaporative emission space and atmospheric pressure; a control in operative association with the timer, the time limit device, the sensor, and the valves for operating the valves to a first set of respective conditions that allows creation of a differential between pressure in the evaporative emission space and atmospheric pressure sufficient to perform a leak detection test on the evaporative emission space, for operating the valves to a second set of respective conditions after the differential has been created to isolate the evaporative emission space so that reduction in the created differential is indicative of leakage from the evaporative emission space, and for operating the valves to a third set of respective conditions after the timer has timed to the defined time limit to selectively reduce the differential, and measuring a parameter related to the selective reduction of the differential between pressure in the evaporative emission space and atmospheric pressure, and utilizing the parameter measurement as a factor for determining leakage from the evaporative emission space. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. A leak detection system for detecting leakage from an evaporative emission space of a fuel storage system that stores volatile liquid fuel for a fuel-consuming engine of an automotive vehicle, including an evaporative emission control having an atmospheric vent path containing a vent valve for venting the evaporative emission space to atmosphere and a vapor purge path for purging fuel vapors from the evaporative emission space to the engine under conditions conducive to purging, the system comprising:
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a timer to measure time; a time limit setting device for setting a defined time limit for the timer; a pressure differential setting device for setting a defined pressure differential; a sensor for sensing the differential between pressure in the evaporative emission space and atmospheric pressure; and a control in operative association with the timer, the time limit setting device, the pressure differential setting device, the sensor, and the valves for
1) operating the valves to a first set of respective conditions that allows creation of a differential between pressure in the evaporative emission space and atmospheric pressure sufficient to perform a leak detection test on the evaporative emission space,
2) operating the valves to a second set of respective conditions after the differential has been created to isolate the evaporative emission space so that reduction in the created differential is indicative of leakage from the evaporative emission space,
3) starting the timer after the evaporative emission space has been so isolated,
4) whenever the sensed differential reaches the defined differential before the timer has timed to the defined time limit, utilizing the measure of time that is present on the timer when the sensed differential between pressure in the evaporative emission space and atmospheric pressure reaches the defined differential as a factor for determining leakage from the evaporative emission space and
5) whenever time on the timer reaches the time limit before the differential reaches the defined differential, operating the valves to a third set of respective conditions to selectively reduce the differential between pressure in the evaporative emission space and atmospheric pressure to the defined differential, and measuring a parameter related to the selective reduction of the differential between pressure in the evaporative emission space and atmospheric pressure, and utilizing the parameter measurement as a factor for determining leakage from the evaporative emission space.
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Specification