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ROBUSTNESS FOR EVAPORATIVE LEAK DETECTION STRATEGY UTILIZING STEERING WHEEL INPUT

IP.com Disclosure Number: IPCOM000249645D
Publication Date: 2017-Mar-13
Document File: 1 page(s) / 196K

Publishing Venue

The IP.com Prior Art Database

Abstract

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ROBUSTNESS FOR EVAPORATIVE LEAK DETECTION STRATEGY UTILIZING STEERING WHEEL INPUT

An Evap leak test commonly used in leak detection strategies is the flow test or gross/medium leak test. This

test is performed during vehicle cruising conditions when the engine stability has been achieved.This test uses

engine vacuum to evacuate the Evap system. The Canister Vent Solenoid (CVS) valve is sealed and the Canister

Purge Valve (CPV) opened to evacuate the Evap system to a target vacuum level (-8 In H2O).From that point,

the CPV is closed and the bleedup is assessed for a gross or medium leak. The leak test has robustness issues

due to fuel vaporization which can cause high bleedups that look like 0.04” leaks (alpha error).Alpha error can

be caused by fuel slosh. When fuel sloshes, the resulting flash generates a pressure increase inside the sealed

Evap system. Prior art methods typically use the Fuel Level Indication (FLI) to infer a fuel slosh event.The FLI is

effective at detecting longitudinal fuel waves(fore-aft) but in most fuel tanks, but the FLI is insensitive to lateral

fuel waves. Lateral waves are caused by steering wheel input and also cause fuel vaporization but are

undetectable using the FLI sensor. During recent test trip, it was observed even very slight steering

perturbations from: busy/nervous driver, rough/bumpy road, can cause considerable fuel vaporization. Even

very slight steering wheel movement from road input when accumulated over time was causing excessive

bleedups….potenti...