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AN EVAP SYSTEM LEAKY CPV MITIGATION ACTION

IP.com Disclosure Number: IPCOM000243732D
Publication Date: 2015-Oct-15
Document File: 1 page(s) / 239K

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AN EVAP SYSTEM LEAKY CPV MITIGATION ACTION

Vehicles sold in North America are required to adsorb refueling, diurnal and running loss hydrocarbon vapors (HC) into a carbon canister. Once the canister is loaded with vapors, engine running manifold vacuum is used to clean out the canister in a process known as "purging." The canister purge valve ("CPV") valve is typically duty cycled as engine vacuum is utilized to suck in fresh air from atmosphere into the canister and displace the trapped vapors into the engine combustion chambers. Vehicles are also required to perform leak diagnostics on the Evap system as part of OBDII requirements. The Evap system is leak checked once per drive cycle and other functional diagnostics are performed on it as part of the OBDII regulations. CPV valves may leak over time as contaminants from the canister carbon dust accumulate inside it. At key off, hydrocarbons escape to the atmosphere through the CPV. HC from inside the canister and HC that evaporate from the fuel tank escape through the leak in the CPV (as the path of least restriction to atmosphere). This is undesirable, as it leads to increased levels of emissions. A leaky CPV valve may also subject the fuel tank to high magnitudes of vacuum, which can cause deformation. Although the MIL turns on when a leaky CPV is detected, a customer may not promptly take the vehicle for service. In the meantime, the CPV leak can serve as a path for vapors to escape to atmosphere during vehi...