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A Rapid Fuel Vapor Atomization Method Using Peltier Heaters for Performing Evap Leak Diagnostics

IP.com Disclosure Number: IPCOM000241954D
Publication Date: 2015-Jun-10
Document File: 1 page(s) / 229K

Publishing Venue

The IP.com Prior Art Database

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A Rapid Fuel Vapor Atomization Method Using Peltier Heaters for Performing Evap Leak Diagnostics

Vehicles sold in North America market 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/hot, 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. If drive cycle is mild and not enough heat rejection is achieved, EONV does not execute. This poses a problem as CARB stipulates completion rate for each OBD monitor (IUMP). EONV's passive nature and human factor dependency hampers IUMP rates as well as monitor robustness.

Method

This method implements an active Evap leak detection diagnostic after key off. This performs an Evap leak diagnostics hours after key off, when the temperature of the fuel inside the tank has stabilized and is near ambient conditions. The PCM wakes up hours after key off and seals the Evap system by...