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AN EVAP SYSTEM WITH HARDWARE TO PINPOINT CANISTER SIDE LEAK LOCATIONS

IP.com Disclosure Number: IPCOM000242002D
Publication Date: 2015-Jun-12
Document File: 1 page(s) / 247K

Publishing Venue

The IP.com Prior Art Database

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 63% of the total text.

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AN EVAP SYSTEM WITH HARDWARE TO PINPOINT CANISTER SIDE LEAK LOCATIONS

Vehicles sold in North America are required to perform Evap leak detection. Green state vehicles are required to monitor for 0.02" leaks. Natural Vacuum techniques are typically used as the leak detection method.For HEV, engine run time is limited, hence a vacuum pump is required for leak detection. One such vacuum pump is the ELCM. The ELCM test sequence begins by obtaining a "reference check" by turning on the pump and evacuating a small volume where an internal 0.02" reference orifice is located. The reference vacuum value obtained becomes the pass/fail threshold.Change Over Valve (COV) is then energized and pump evacuates the entire Evap system. In absence of a leak, the pump pulls down to the reference check value. In presence of a leak, pump does NOT pull down to the reference check value.When ELCM monitor executes to perform leak detection, ELCM Vacuum pump checks the canister side of the Evap system (FTIV) closed. If canister side passes, then FTIV is opened and ELCM checks the entire system to infer tank side is leak free. ELCM is unable to determine which side of the canister is leaking, or even if the canister itself is leaking.

Method

This method pinpoints the location of the leak on the canister side: vent side, purge side or canister itself. This is done by reversing the canister circuitry for the canister's purge and vent ports and a thermocouple inside the canister. The ELCM...