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A METHOD TO DETECT TINY FUEL TANK LIQUID LEAKS

IP.com Disclosure Number: IPCOM000241982D
Publication Date: 2015-Jun-11
Document File: 1 page(s) / 228K

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The IP.com Prior Art Database

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A METHOD TO DETECT TINY FUEL TANK LIQUID LEAKS

Vehicles sold in North America market are required to perform Evap leak detection as part of OBDII requirements. Green states required to monitor for 0.02" leaks as part of the Clean Air Act Section 177. (CAA). For regular gasoline engines, a technique called Engine Off Natural Vacuum (EONV) is used to perform leak detection or a pump based system called ELCM is used.While EONV and other pump based ELCM are adequate at detecting leaks in the Evap system vapor space, these methods do not detect leaks in the fuel tank liquid space. Liquid space leaks are typically detected visually by fuel spill or smell of fuel scent under the vehicle. However, when liquid leak is small enough, the tiny hole does not allow liquid droplets to escape to outside of fuel tank, but does allow hydrocarbons to escape to the atmosphere. This is especially true if there is no liquid head pressure to force the liquid fuel outside the tiny hole in the fuel tank. This condition is undesirable as it leads to increased levels of emissions and customer complaints of fuel odor.

Method

This method detects very tiny leaks in the fuel tank liquid space at key off by pressurizing the vapor dome and inducing a motive force to induce liquid to escape out of the tiny leak.First, the ELCM leak monitor executes in its normal state (vacuum) to ensure that the vapor space is leak free.After the vapor space is validated to be leak free, the liquid space leak...