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OPPORTUNISTIC EVAPORATIVE LEAK DETECTION STRATEGY METHOD

IP.com Disclosure Number: IPCOM000248881D
Publication Date: 2017-Jan-19
Document File: 1 page(s) / 277K

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The IP.com Prior Art Database

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OPPORTUNISTIC EVAPORATIVE LEAK DETECTION STRATEGY METHOD

Vehicles sold in the United States 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.

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, if the drive cycle resulted in adequate heat rejection into the liquid fuel,

the PCM stays alive and seals the Evap system by closing the CVS. If the strategy infers adequate heat

rejection, the EONV technique is performed. Unfortunately Hybrid Electric (“HEVs”) and Start Stop

(“S/S”) Vehicles may have difficulty heating up the bulk fuel to perform EONV testing. Some drive cycles

are inherently short. People living in mega cities and other customers' lifestyles may have frequent drive

cycles that are very short and periodic. The end result is EONV does not have a chance to execute due to

low drive cycle and hence execution rates suffer.

Method

This method provides an opportunistic method short drive cycles that do not enable EONV since these

drive cycles generate minimal heat rejection for EONV to run reliably. This method looks for the

opportunity to perform a 0.02” leak detection during based on the “delta temperature” between the

long term average vehicle parking venue and the final de...