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EONV METHOD WITH MULTIPLE ACTIVELY COOLED VENT CYCLES

IP.com Disclosure Number: IPCOM000240975D
Publication Date: 2015-Mar-16
Document File: 1 page(s) / 217K

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The IP.com Prior Art Database

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EONV METHOD WITH MULTIPLE ACTIVELY COOLED VENT CYCLES

Vehicles sold in North America are required to perform Evap leak detection as part of OBDII requirements. Green states required to monitor for 0.02" leaks as part of the Clean Air Act Section 177. (CAA).For regular gasoline engines, a technique called Engine Off Natural Vacuum (EONV) is used to perform leak detection. EONV relies on heat rejection from the hot engine to reach the tank and warm the bulk fuel during driving.At key off, PCM stays alive and seals the Evap system by closing the CVS. EONV can either pass on a pressure build or on a vacuum build. If sufficient heat is rejected into the fuel tank and the temperature outside is warm, the outcome is EONV passes on a pressure build. If moderate heat is rejected and temperature outside is mild/cool, EONV passes on vacuum phase. When the initial pressure rise stalls out, the Evap system is vented and resealed in anticipation of vacuum. Although most of the time vacuum develops, there are times when a 2nd pressure phase develops but with less intensity than the initial pressure phase. The 2nd pressure phase is from residual heat rejection that is still present in the system. The 2nd pressure phase typically does not generate enough pressure to pass the monitor. It delays the monitor from developing vacuum. EONV is time limited and failure to build enough vacuum or pressure results in a MIL setting.

Method

This method implements more than one EONV vent cy...