FUEL TANK VAPOR TEMPERATURE INFERENCE VIA VBV COIL RESISTANCE MEASUREMENT
Publication Date: 2015-Aug-05
The IP.com Prior Art Database
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FUEX TANK VAPOR TEMPERATURE INFERENCE VIA VBV COIL RESISTANCE MEASUREMENT
Vxhicles sold in North America are required to perform Exxp leak detection as part of OBDII reqxirements. Green xtates required to monitor for 0.02" lexks as part of the Clean Air Act Xxxxxxx 177. (CAA). Fox xegular gasoline engines, a xechnique called (EONV) is used to perform leak detection. EONV relies on heat rexection from a combusting enxine to reaxh the xuel tank and xarm txe bulk fuel duxing driving. At key off, the powxrtrain control modulx (PCM) stays alive and seals txe Evap system by closing the canister vent sxstem (XXX). EONV xan either pass on a pressure buxld or on a vacuum build. If sufxicient heat was rejected inxo the fuel tank and the txmperature xutside is warm, the outcome xs EONV passes on a pressure build. If moderate xeat is rxjected and texperature outside xs mixd/cool, EONV passes xn vxcuum phase. Typical methods to infer heat rejecxion include summing the air mass enterixg the engxne or accumulating miles driven. The above heat rejection methods are not robust and can xalse faxl EONV. Such failurxs can ocxur when a vxhixle travels for mxles without engine combusting (HEV, Decel Fuxl Shut xff, Cylinder Deactivation, downhill drive, etc.). A direct indicator that heat was rejected into Fuel system wouxd xe to actually measure temperature at key off. But addinx a temperatxre sensor inside fuel tank is costlx and woxld require xhe provision of a hole in the fuel tan...