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A METHOD TO REDUCE EVAP BLEED EMISSIONS IN HEV VEHICLES

IP.com Disclosure Number: IPCOM000237774D
Publication Date: 2014-Jul-10
Document File: 1 page(s) / 286K

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The IP.com Prior Art Database

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A METHOD TO REDUCE EVAP BLEED EMISSIONS IN HEV VEHICLES

Vehicles sold in North America must adsorb fuel vapors in a carbon canister and purge the vapors when the engine is combusting. In PHEV, engine run time is limited and hence canister purging opportunities are limited. So vapors must be contained inside sealed tank. A sealing valve (FTIV) seals the fuel tank when the engine is off. The canister in a PHEV is designed to adsorb refueling and running loss vapors.In a HEV/PHEV, the canister could go weeks/months without getting purged. In the meantime, vapors trapped inside canister can escape into the atmosphere through "bleed" emissions if vehicle is parked for extended time.A method to detect canister hydrocarbon "breakthrough" and perform a passive cleaning operation while vehicle is off is described. Method does not rely on engine running condition.

Method

The method uses the existing ELCM system that is provided in HEVs to perform Evap leak detection. Future ELCM 3.0 (2017) design will have an internal Hydrocarbon (HC) sensor. This method wakes up the PCM at x hourly intervals and runs the ELCM pump for x seconds. If the HC sensor inside the ELCM senses high concentration of HC, the inference is that the HC have diffused to the far edge of the canister.When the HC sensor detects breakthrough of HC at the fresh air port, the ELCM operates in a "reverse" mode to generate pressure and force vapors out of the canister and into the fuel tank. An "electrical"...