Method for Purging Evap System’s Carbon Canisters at High Altitudes and WOT Operations
Publication Date: 2014-Jan-15
The IP.com Prior Art Database
Page 01 of 1
Method for Purging Evap System's Carbon Canisters at High Altitudes and WOT Operations
Vehicles sold in North America contain a carbon canister that adsorbs refueling, diurnal and running loss vapors. Engine running manifold vacuum is used to desorb the vapor from the activated carbon canister via opening of CPV valve. Desorbed vapors are combusted in engine. This desorption is commonly known as "purging". Vehicles have limited engine purge at high altitudes due to less air density in the atmosphere which results in less vacuum in the intake. Low or no vacuum magnitudes means loaded canister cannot be purged. Also, this applies to the vehicles that have limited engine vacuum. i.e., small engines towing a trailer typically have limited intake manifold vacuum. Furthermore, low vacuum also is present in GTDI engines when it operates in a hysteresis band between vacuum and boost. Finally, a vehicle that refuels at the bottom of a hill (refueling loads the canister) and then climbs a steep hill for instance, will not be able to purge the canister due to Wide Open throttle (WOT)driving with no intake vacuum. Hydrocarbon (HC) emissions and fuel scent in the cabin could result. Hence a method is needed to purge canister at high altitudes, WOT conditions, and low vacuum applications such as GTDI engines.
The invention aims to utilize vehicle motion to generate a pressure "purge" in the direction of the purge flow to assist with cleaning the canister. A three-way v...