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LEAK DETECTION WITH COMBINED PRESSURE AND TEMPERATURE INFORMATION

IP.com Disclosure Number: IPCOM000241546D
Publication Date: 2015-May-08
Document File: 1 page(s) / 220K

Publishing Venue

The IP.com Prior Art Database

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LEAK DETECTION WITH COMBINED PRESSURE AND TEMPERATURE INFORMATION

Vehicles sold in North America are required to perform Evap Leak Diagnostics. For Federal standards, a leak size of 0.04" needs to be detected. For green States, a leak size of 0.02" needs to be detected. Current EONV (Engine-Off Natural Vacuum) uses pressure changes in a sealed system to validate leak integrity. Most existing methods of this type use multiple calibratable tables to determine pressure thresholds with inputs such as temperature, fuel level, fuel type and drive content such as cumulative trip distance, drive ratio and air mass consumed for engine combustion. Multiple thresholds may be applied simultaneously (i.e. pressure build-up and vacuum) to allow leak detection to be sensitive to major impacting factors and physical contraints imposed to a sealed system. Current EONV method with pressure only information is prone to false failures. This is due the reduced contrast (between class separations) between leak vs no leak system as the influence from various noise factor increases.

Method

This method uses an additional temperature sensor in the Evap system. The vapor pressure change and the corresponding temperature change are used in the new diagnostic feature calculation to determine if a leak is present in the system (0.02" or larger). Because accumulated pressure rate change (∆P) leads to the final pressure value, proposed method generally reaches extreme values earlier than ori...