Method and system for aggressive cycling of leak detection pump to ascertain vapor leak size
First Claim
1. A method for detecting leakage from a contained volume for holding volatile liquid during a leak test, the method comprising:
- operating a reciprocating pump in a pressurizing mode to build pressure in headspace of the contained volume toward a nominal test pressure, the pressurizing mode comprising operating the pump in a repeating cycle that comprises operating the pump alternately in an accelerated pumping mode and a natural frequency pumping mode;
during the pressurizing mode, measuring a characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the headspace;
counting the number of times the cycle repeats and comparing the count to a predefined reference;
when the cycle count exceeds the predefined reference, continuing the test at a lower resolution for detecting leakage; and
when the cycle count does not exceed the predefined reference and a measurement of the characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the headspace exceeds a predetermined reference pressure, continuing the test at a higher resolution for detecting leakage.
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Accused Products
Abstract
A system and method for detecting leakage from a evaporative emission space of an automotive vehicle fuel system. A reciprocating pump is operated in a pressurizing mode to build pressure in the space toward a nominal test pressure. The pressurizing mode involves operating the pump in a repeating cycle wherein the pump operates alternately in an accelerated pumping mode and a natural frequency pumping mode. During the pressurizing mode, a characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the space is measured. The number of times the cycle repeats is counted and compared to a predefined reference. When the cycle count exceeds the predefined reference, the test continues at a lower resolution for detecting leakage, and when the cycle count does not exceed the predefined reference and a measurement of the characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the space exceeds a predetermined reference pressure, the test continues at a higher resolution for detecting leakage. The invention is useful when overall test time is limited.
16 Citations
24 Claims
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1. A method for detecting leakage from a contained volume for holding volatile liquid during a leak test, the method comprising:
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operating a reciprocating pump in a pressurizing mode to build pressure in headspace of the contained volume toward a nominal test pressure, the pressurizing mode comprising operating the pump in a repeating cycle that comprises operating the pump alternately in an accelerated pumping mode and a natural frequency pumping mode;
during the pressurizing mode, measuring a characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the headspace;
counting the number of times the cycle repeats and comparing the count to a predefined reference;
when the cycle count exceeds the predefined reference, continuing the test at a lower resolution for detecting leakage; and
when the cycle count does not exceed the predefined reference and a measurement of the characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the headspace exceeds a predetermined reference pressure, continuing the test at a higher resolution for detecting leakage. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for detecting, during a leak test, leakage of vapor from an evaporative emission space of a fuel storage system of an automotive vehicle for storing volatile fuel consumed by the vehicle during operation, the method comprising:
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operating a reciprocating pump in a pressurizing mode to build pressure in the evaporative emission space toward a nominal test pressure, the pressurizing mode comprising operating the pump in a repeating cycle that comprises operating the pump alternately in an accelerated pumping mode and a natural frequency pumping mode;
during the pressurizing mode, measuring a characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the evaporative emission space;
counting the number of times the cycle repeats and comparing the count to a predefined reference;
when the cycle count exceeds the predefined reference, continuing the test at a lower resolution for detecting leakage; and
when the cycle count does not exceed the predefined reference and a measurement of the characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the evaporative emission space exceeds a predetermined reference pressure, continuing the test at a higher resolution for detecting leakage. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A system for indicating leakage from a contained volume for holding volatile liquid during a leak test, the system comprising:
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a reciprocating pump for building pressure in headspace of the contained volume toward a nominal test pressure; and
a control, including a processor, for;
operating the pump in a pressurizing mode comprising operating the pump in a repeating cycle that comprises operating the pump alternately in an accelerated pumping mode and a natural frequency pumping mode;
measuring a characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the headspace while in the pressurizing mode;
counting the number of times the cycle repeats and comparing the count to a predefined reference;
continuing the test at a lower resolution for detecting leakage when the cycle count exceeds the predefined reference; and
continuing the test at a higher resolution for detecting leakage when the cycle count does not exceed the predefined reference and a measurement of the characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the headspace exceeds a predetermined reference pressure.- View Dependent Claims (15, 16, 17, 18, 19)
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20. A system for detecting leakage, during a leak test, of vapor from an evaporative emission space of a fuel storage system of an automotive vehicle for storing volatile fuel consumed by the vehicle during operation, the system comprising:
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a reciprocating pump for building pressure in evaporative emission space toward a nominal test pressure; and
a control, including a processor, for;
operating the pump in a pressurizing mode comprising operating the pump in a repeating cycle that comprises operating the pump alternately in an accelerated pumping mode and a natural frequency pumping mode;
measuring a characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the evaporative emission space while in the pressurizing mode;
counting the number of times the cycle repeats and comparing the count to a predefined reference;
continuing the test at a lower resolution for detecting leakage when the cycle count exceeds the predefined reference; and
continuing the test at a higher resolution for detecting leakage when the cycle count does not exceed the predefined reference and a measurement of the characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the evaporative emission space exceeds a predetermined reference pressure.- View Dependent Claims (21, 22, 23, 24)
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Specification