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Determination of Fuel Tank Run Dry by Monitoring Fuel Pressure

IP.com Disclosure Number: IPCOM000237184D
Publication Date: 2014-Jun-06
Document File: 1 page(s) / 272K

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The IP.com Prior Art Database

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Determination of Fuel Tank Run Dry by Monitoring Fuel Pressure

The accuracy of a conventional, pivoted float-type fuel level sender (1)* reduces at very low fuel tank levels because of the tolerance stack up on the assembly of the unit inside the fuel tank (2). This makes it difficult to:
 robustly determine the minimum fuel level at which a diesel engine should be shut down to protect fuel system components running dry, and

 ensure that the fuel level does not fall so low that re-fuelling from a proprietary fuel canister fails to raise the level above the fuel pump pickup (3).

The diagram shows a fuel tank with a fuel level sender (1), the float of which is at a level, below which measurement of the fuel level is very inaccurate or even unmeasurable. Some applications include a separate level switch in the diesel delivery module (4) and this can be positioned lower than the level at which the pivoted sender can operate. If the fuel level falls very low, air bubbles can be drawn in to the fuel pump pickup. A smart solution to detect a very low fuel level is to delete the level switch and monitor the effect of the bubbles on the pressure in the feed line (5).

For a system with open loop fuel pump control, an entrained air bubble results in a momentary drop in fuel pressure, which can be detected by a pressure switch. Such a switch may be installed as part of a Fuel Filter Minder feature. For system with closed loop fuel pump control, a momentary pressure red...