Method and system for aggressive cycling of leak detection pump to ascertain vapor leak size

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:

• 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.

A system for indicating leakage from a contained volume for holding volatile liquid during a leak test, the system comprising:

• 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.

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:

• 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.