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AN EVAP SYSTEM WITH CONDENSER UNIT TO MINIMIZE DIURNAL BLEED EMISSIONS

IP.com Disclosure Number: IPCOM000240777D
Publication Date: 2015-Feb-27
Document File: 1 page(s) / 236K

Publishing Venue

The IP.com Prior Art Database

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AN EVAP SYSTEM WITH CONDENSER UNIT TO MINIMIZE DIURNAL BLEED EMISSIONS

Strict Evaporative emission standards must be met for vehicles to be certified in North America. Once canister is loaded with refueling, running loss and diurnal vapors, engine manifold vacuum is used to clean out the canister in a process known as "purging". Canister is never purged out completely since air does not flow uniformly inside it. Some regions inside the canister see better air flow than others. Those regions that do not see good air flow typically still retain Hydrocarbon (HC) vapor. Trapped vapors contribute to bleed emissions when vehicle is parked over 2 or 3 days in the hot sunny climates. This is especially relevant with HEVs and Start/Stops since engine run time is limited and hence purging is limited. Common strategy to limit bleed emissions is adding a secondary "bleed" canister for PZEV vehicles to capture them (adds cost, weight and packaging). But if vehicle is parked outside for extended times, even with a bleed element, emissions still occur.Bleed canister is typically honeycombed structured and highly restrictive. It can impede refueling function and cause pre mature pump shutoffs. It also adds restriction to the Evap circuit and adds to extra time to clean out the canister on cycle.

Method

The method minimizes the HC emissions over 2 and 3 day diurnal SHED testing by placing a condenser at the load port of the canister connection to the fuel tank. The vapors gener...