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AN EMISSION LOWERING METHOD FOR START/STOP AND HEV VEHICLES

IP.com Disclosure Number: IPCOM000241462D
Publication Date: 2015-May-01
Document File: 1 page(s) / 221K

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AN EMISSION LOWERING METHOD FOR START/STOP AND HEV VEHICLES

Vehicles sold in North America are required to adsorb refueling, diurnal and running loss vapors into a carbon canister. Strict Evap emission standards must be met for vehicles to be certified.Once a canister is loaded with vapors, the engine running manifold vacuum is used to clean out the canister in a process known as "purging". Start/stop vehicles typically deactivate the engine when the vehicle comes to an idle stop. This is prevalent in city driving to maximize fuel economy.Mild HEVs are similar to S/S and can even drive in battery mode for a limited time before engine kicks in.Purging requires a combusting engine.The CPV is typically opened and fresh air enters the canister from the fresh air line inlet. Fresh air displaces the vapors inside the canister and they are sucked into the intake manifold to be combusted inside the engine.During idle stops and battery driving, the canister cannot be purged. Once engine combusts again, purging can commence.Purge command is typically slowly ramped in as to not allow the engine to inhale large amounts of canister vapors which can stall the engine.While running loss and diurnal vapors load the canister slowly, a refueling event is a significant loading of the canister and can easily saturate it on a hot summer day if fuel RVP is high. Failure to purge right after a refueling event can lead to increased levels of emissions.

Method

This method limits e...