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A METHOD TO INFER CPV LEAKAGE LEARNING AND PERFORM COMPENSATION

IP.com Disclosure Number: IPCOM000235605D
Publication Date: 2014-Mar-11
Document File: 1 page(s) / 233K

Publishing Venue

The IP.com Prior Art Database

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A METHOD TO INFER CPV LEAKAGE LEARNING AND PERFORM COMPENSATION

Vehicles sold in North America market are required to capture fuel vapors and store them inside a carbon canister. Vehicles are also required to perform leak checking/diagnostics on the Evap system. Engine vacuum is typically used to purge the carbon canister and recover the vapors into the intake where they are combusted in the cylinders.The CPV valve is used as the gateway for the vapor path into the engine. The CPV is duty cycled depending on how much vapor loading is inside the canister and other engine conditions. Too much vapor introduced into the engine from the canister can actually stall the engine.The Evap system is also leak checked once per drive cycle and other functional diagnostics are performed on it as part of the OBDII regulations.One such diagnostic is the leaky CPV test. Leaky CPV diagnostic closes both the CPV and CVV to seal the Evap system. If any vacuum builds up inside the fuel tank with the CPV commanded closed, inference is that CPV is leaking. CPVs typically leak over time as contaminants from canister carbon dust accumulates inside it. It is imperative that the CPV leak be recognized as to not stall the engine or damage the fuel tank.

Method

This strategy infers the amount of CPV leakage and compensates for the leakage by reducing the duty cycle that is commanded to the CPV by the amount of leakage. This ensures that accurate purge flow is being delivered to the engin...