Claims:We Claim

1. A fuel filter (10), said fuel filter (10) comprising:
a top cap (12);
a fuel filter element (14), a top portion of said fuel filter element (14) secured to said top cap (12);
a bottom cap (16) secured to a bottom portion of said fuel filter element (14); characterized in that
a drain plug (18) secured to said bottom cap (16), said drain plug (18) adapted to facilitate retaining water that is collected in said fuel filter (10).

2. The fuel filter (10) in accordance with Claim 1 wherein said bottom cap (16) comprises a flat portion (21) that is secured to said fuel filter element (14) and a U-shaped portion (19) that extends from said flat portion (21), said U-shaped portion (19) having a plurality of screw threads defined along an inner diameter of said U-shaped portion (19), said drain plug (18) adapted to be secured to said U-shaped portion (19) by screwing said drain plug (18) onto said plurality of screw threads that are defined along the inner diameter of said U-shaped portion (19).

3. The fuel filter (10) in accordance with Claim 2 wherein said flat portion (21) of said bottom cap (16) is secured to said fuel filter element (14) by means of a fastener.

4. The fuel filter (10) in accordance with Claim 1 wherein said fuel filter element (14) has a bore defined therethrough and having a plurality of screw threads defined along an inner diameter of the bore, said drain plug (18) adapted to be secured to said fuel filter element 14 by screwing said drain plug (18) onto said plurality of screw threads that are defined along the inner diameter of said bore of said fuel filter element 14.
, Description:Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention relates to a fuel filter, and more specifically to a drain plug that is screwed to a bottom cap of the fuel filter.

Background of the invention
[0002] KR 20030025333 A describes a water sensor structure of a fuel filter. A fuel filter is provided to notify an amount of water contained in a water collector to a driver by installing a water sensor in the fuel filter used in a diesel engine. A water sensor structure includes a fuel filter for filtering fuel. An element is accommodated in an inner portion of a filter body about a central pipe. An upper portion of the filter body is covered with a cover. An anti-overflow valve for preventing fuel from overflowing through the cover and a fuel inlet/outlet section are formed in the cover. A water collector is formed under a filter body so as to store water passing through the element. A drain plug is formed at a lower surface of the water collector so as to discharge water from the water collector. A water sensor is installed in the water collector.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a fuel filter in one embodiment of the invention.

Detailed description of the embodiments
[0006] Figure 1 illustrates a fuel filter 10. The fuel filter 10 comprises a top cap 12, a fuel filter element 14, a top portion of the fuel filter element 14 secured to the top cap 12 via a fastener. A bottom cap 16 is secured to a bottom portion of the fuel filter element 14. A drain plug 18 is secured to the bottom cap 16, the drain plug 18 adapted to facilitate retaining water that is collected in the fuel filter 10.

[0007] The fuel filter 10 comprises a top cap 12. A fuel filter element 14 is secured to the top cap 12. More specifically, a top portion of the fuel filter element 14 is secured to the top cap 12. A bottom cap 16 is secured to the fuel filter element 14. More specifically, the bottom cap 16 is secured to a bottom portion of the fuel filter element 14 by any fastening means that is known in the art. The bottom cap 16 comprises a first flat shaped portion, a second flat shaped portion, and a U-shaped portion that is defined between the first flat shaped portion and the second flat shaped portion. The U-shaped portion comprises a bore and internal threads that are defined along the internal diameter of the bore.

[0008] A drain plug 18 is secured to the bottom cap 16. More specifically, the drain plug 18 is inserted within the U-shaped portion such that the external threads that are defined on the outer diameter of the drain plug 18 are screwed onto the internal screw threads that are defined on the bore of the U-shaped portion. Once the drain plug 18 is screwed onto the bore of the U-shaped portion, the drain plug 18 and bottom cap 16 are sealed and constitute a unitary assembly. Due to the integral nature of the bottom cap 16 with the fuel filter element 14, it is not possible to separate the fuel filter element 14 from the bottom cap 16. In the event that the fuel filter element 14 is separated from the fuel filter 10, the bottom cap 16 is also separated from the fuel filter 10. Therefore, the drain plug 18 cannot be inserted into the U-shaped portion, thereby leaving the bore of the U-shaped portion uncovered. As a consequence, any fuel entering the fuel filter 10 will be drained out of the fuel filter element 14 via the bore of the U-shaped portion. Therefore, no fuel is supplied from the outlet of the fuel filter 10.

[0009] A working of the drain plug 18 of the fuel filter 10 is described as an example. The top cap 12, the fuel filter element 14, and the bottom cap 16 are assembled together within the fuel filter 10. The drain plug 18 is inserted within the U-shaped portion such that the external threads that are defined on the outer diameter of the drain plug 18 are screwed onto the screw threads that are defined along the bore of the U-shaped portion to constitute a unitary assembly. Fuel is now allowed to flow through the fuel filter 10 from the fuel tank. The fuel filter element 14 filters the fuel that flows from the fuel tank and delivers pure fuel to the high pressure fuel pump. When the fuel filter element 14 is removed from the fuel filter 10, the bottom cap 16 that constitutes a unitary assembly with the fuel filter element 14 is also disengaged from the fuel filter 10. Therefore, it is not possible to screw the drain plug 18 onto the fuel filter 10 because the U-shaped portion of the bottom cap 16 that receives the drain plug 18 within it has been removed from the fuel filter 10. If fuel flows into the fuel filter 10 via the inlet of the fuel filter 10, the fuel would drain out from the fuel filter 10 via the bore of the U-shaped portion and not get delivered for pressurization from the fuel filter 10 to the high pressure fuel pump. As a consequence, it is not possible to operate the fuel filter 10 when the fuel filter element 14 has been removed from the fuel filter 10.

[0010] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the scope of the claims.