COMBINATION PRESSURE- AND VACUUM-BASED EVAP LEAK DETECTION METHOD
First Claim
1. A method for conducting leak detection in an evaporative emission control system, comprising:
- performing a pressure-based leak test at selected intervals, including pressurizing the system, using a pump;
monitoring the system pressure for a selected period;
identifying an initial leak if system pressure falls below a threshold value during the selected period;
upon identifying the initial leak, substituting a vacuum-based leak test at each selected interval, including evacuating the system, using the pump;
monitoring the system pressure for a selected period;
identifying a subsequent leak if system pressure rises above a threshold value during the selected period; and
upon receiving notification that the initial leak has been repaired, returning to pressure-based leak testing.
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Accused Products
Abstract
A method and system for conducting leak detection in an evaporative emission control system. The method performs a pressure-based leak test at selected intervals. The pressure-based test includes pressurizing the system, using a pump. Then, the system monitors pressure for a selected period. If system pressure falls below a threshold value during the selected period, the system identifies an initial leak. Upon identifying the initial leak, the system substitutes a vacuum-based leak test at each selected interval. The vacuum-based test includes evacuating the system, using the pump. The system then monitors system pressure for a selected period. If system pressure rises above a threshold value during the selected period, then the system identifies a subsequent leak. Upon receiving notification that the initial leak has been repaired, the system returns to pressure-based leak testing. Where a single pump is used, that pump is configured both for system pressurization and evacuation.
20 Citations
8 Claims
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1. A method for conducting leak detection in an evaporative emission control system, comprising:
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performing a pressure-based leak test at selected intervals, including pressurizing the system, using a pump; monitoring the system pressure for a selected period; identifying an initial leak if system pressure falls below a threshold value during the selected period; upon identifying the initial leak, substituting a vacuum-based leak test at each selected interval, including evacuating the system, using the pump; monitoring the system pressure for a selected period; identifying a subsequent leak if system pressure rises above a threshold value during the selected period; and upon receiving notification that the initial leak has been repaired, returning to pressure-based leak testing. - View Dependent Claims (2, 3, 4, 5)
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6. A leak detection unit in an evaporative emission control system, including an Evaporation Level Check Monitor (ELCM), the ELCM comprising:
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a pressure sensor configured to detect pressure within the ELCM and the evaporative emission control system; a reference orifice for determining a reference pressure value; and at least one pump configured both to pressurize the evaporative emission control system, and to evacuate the evaporative emission control system, as required by the evaporative emission control system. - View Dependent Claims (7, 8)
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Specification