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Detection of Plumbing Disconnect in Ejector Portion of Fuel Vapor Purge System Disclosure Number: IPCOM000241283D
Publication Date: 2015-Apr-13
Document File: 1 page(s) / 111K

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The Prior Art Database

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Detection of Plumbing Disconnect in Ejector Portion of Fuel Vapor Purge System

Boosted engines use ejectors to draw fuel stored fuel vapor into the engine to purge the fuel vapor storage canister. There is a desire to detect disconnects in fuel vapor purge systems because an undetected disconnect may cause fuel vapors to escape into the atmosphere.

Ejector plumbing may become disconnected at 1) the suction port, 2) the post-compressor connection, or
3) the pre-compressor connection. If any of these points become disconnected, it can be detected because a vacuum fails to form in the fuel vapor system if the canister vent valve is closed. An example method using this principle is described below.

1. Wait for the engine condition where MAP > BP. (I.e. no vacuum is supplied by the intake manifold). And wait for the engine condition where TIP > CIP + 20 kPa. (I.e. ejector is producing significant vacuum).

2. Verify that the Fuel Tank Pressure Transducer (FTPT) is reading near zero gauge pressure, if so, proceed.

3. Temporarily open the Vapor blocking Valve (VBV) and close the Canister Vent Valve (CVV). This exposes the FTPT to ejector vacuum.

4. Open or continue to open the Canister Purge Valve (CPV).

5. Wait a short time period (e.g.10 seconds) to allow vacuum to develop in canister, tank, and lines. 6. Sample the FTPT. If it reports a vacuum deeper than a threshold value (e.g. 6 kPa), conclude that the ejector connections are intact. Else, report a system fault.