Patent Application
20100186724
The present disclosure relates to engine fuel systems, and more specifically to removal of gases from fuel filters.
This section provides background information related to the present disclosure which is not necessarily prior art.
Engine assemblies may include a fuel system having a fuel filter. The fuel filter may include a filter casing housing a filter media. During engine operation, liquid fuel may be passed through the filter media and delivered to the engine. However, gases such as fuel vapors and air may accumulate in the filter casing, reducing the area of the filter media exposed to liquid fuel.
An engine assembly may include an engine defining a cylinder bore, a fuel tank, a fuel supply assembly in fluid communication with the fuel tank and the cylinder bore, a fuel return assembly in fluid communication with the fuel supply assembly and the fuel tank to return excess fuel from the fuel supply to the fuel tank, and a fuel filter assembly. The fuel filter assembly may include a filter casing having an inlet, an outlet and a bypass opening, and a filter media located within the filter casing. The filter media may be located between the inlet and the outlet, defining a dirty fuel region of the filter assembly between the inlet and the filter media and a clean fuel region between the filter media and the filter outlet. The bypass opening may be in fluid communication with the dirty fuel region and the fuel return assembly to draw gases out of the dirty fuel region.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
With reference to
The fuel regulation assembly 32 may regulate the supply of pressurized fuel provided to the individual cylinder bores 14. The fuel may be provided to the individual cylinder bores 14 via fuel injectors (not shown) and the pressure supplied to the injectors may be regulated by a pressure regulation mechanism (not shown), such as a valve. By way of non-limiting example, the fuel may be provided to the individual cylinder bores 14 by direct injection. In configurations where the fuel pump 26 is only a suction-type pump, the fuel regulation assembly 32 may include a separate high pressure pump further pressurizing the fuel provided to the fuel injectors. The fuel regulation assembly 32 may include a separate pressure regulation valve or a pressure regulation valve integral to the high pressure pump. The present disclosure applies to a variety of fuels including, but not limited to, diesel fuel and gasoline.
The fuel return assembly 20 may include a fuel return line 36 in fluid communication with the fuel regulation assembly 32 and the fuel tank 16. The fuel return line 36 may include a restriction mechanism 38 located between the fuel tank 16 and the fuel regulation assembly 32, separating the fuel return line 36 into first and second portions 37, 39. The fuel filter assembly 22 may be in fluid communication with the fuel tank 16 as well.
The fuel filter assembly 22 may include a filter casing 40 housing a filter media 42 and a bypass line 44. The filter casing 40 may include an inlet 46, an outlet 48, and a bypass opening 50. The filter media 42 may define a dirty fuel region 52 within the filter casing 40 between the inlet 46 and the filter media 42 and a clean fuel region 54 between the filter media 42 and the filter outlet 48. The bypass opening 50 may be in fluid communication with the dirty fuel region 52 and may be located at an upper portion of the filter casing 40.
Locating the bypass opening 50 at the upper portion of the filter casing 40 may provide fluid communication between a gas-containing portion of the filter casing 40 and the bypass opening 50. The gases within the fuel filter casing 40 may include fuel vapors and air. The gases may accumulate at the upper portion of the fuel filter casing 40 due to the higher density of the liquid fuel within the filter casing 40. Removal of gases from the filter casing 40 may provide an increased exposure of the filter media 42 to liquid fuel, resulting in lower fuel velocities traveling through the filter media 42 and a greater utilization of the entire surface area of the filter media 42. The bypass line 44 may be in fluid communication with the bypass opening 50 and the restriction mechanism 38 to provide flow from the dirty fuel region 52 to the fuel tank 16 via the fuel return line 36, and more specifically, for flow of gases from the filter casing 40 to the fuel tank 16. The bypass line 44 may include a flow limiting mechanism 55, such as an orifice, to limit the amount of flow, and more specifically the amount of liquid fuel flow, through the bypass line 44.
During engine operation, pressurized fuel may be supplied to the engine 12 by the fuel pump 26. Excess fuel may be returned to the fuel tank 16 by the fuel regulation assembly 32. As the fuel returns to the fuel tank 16, it passes through the restriction mechanism 38. As seen in
As fuel flows through the restriction mechanism 38, fuel pressure is reduced and velocity is increased as the fuel flows through the duct 60. The fluid pressure within the duct 60 and/or at the entrance to the duct 60 may be less than the fluid pressure within the dirty fuel region 52 of the fuel filter assembly 22 during some engine operating conditions due to varying fuel demand. The second portion 39 of the fuel return line 36 and the outlet diameter (D5) may be sized to provide a low pressure drop from the diverging nozzle portion 58 to the fuel tank 16. The duct 60 may be sized to provide a fuel pressure therein less than the fuel pressure within the dirty fuel region during some engine operating conditions as discussed above to periodically purge the gases from the fuel filter assembly 22.
As the fuel flows from the duct 60 through the diverging nozzle portion 58, the velocity decreases and pressure again increases. The localized increase in velocity and reduction in pressure may draw the gases from within the fuel filter casing 40 to the fuel tank 16. By way of non-limiting example, the bypass line 44 may be in fluid communication with the duct 60 of the restriction mechanism 38. More specifically, the bypass line 44 may be in fluid communication with an outlet of the duct 60. Fuel gases may be drawn from the fuel filter casing 40 of the fuel filter assembly 22 into the fuel return line 36 by the pressure reduction created within the restriction mechanism 38.
