Claims:We Claim
1 A multistage fuel filter assembly comprising:
a housing (12);
a top cap (18) fitted to one end of said housing (12) and comprising an air vent knob (26); and
a base cap (20) fitted to second end of said housing (12) and comprising a drain plug (28);
characterized in that said multistage fuel filter assembly comprising at least two filter elements;
a first filter element (22) enclosed within said housing (12), said first filter element (22) comprising a first base plate (22d) fitted to said housing (12) and said first base plate (22d) comprising at least one opening (22b) in flow communication with a second filter element (24); and
said second filter element (24) enclosed within said housing (12), said second filter element (24) comprising a second base plate (24b) fitted to said housing (12) and located below said first filter element (22), said second base plate (24b) comprising at least one opening (24c) in flow communication with said base cap (20).
2 The multistage fuel filter assembly as claimed in claim 1, wherein said first base plate (22d) is fitted to said housing (12) using a first groove in the housing (12).
3 The multistage fuel filter assembly as claimed in claim 1, wherein said second base plate (22d) is fitted to said housing (12) using a second groove in the housing (12).
4 The multistage fuel filter assembly as claimed in claim 1, wherein said housing (12) comprises an inlet path (14) located at an operative top end of said housing (12) and an outlet path (16) located at an operative bottom end of said housing (12).
5 The multistage fuel filter assembly as claimed in claim 1, wherein said first filter element (22) defines a first annular cavity (22c) adapted to receive fuel filtered by said first filter element (22).
6 The multistage fuel filter assembly as claimed in claim 1, wherein said second filter element (24) defines a second annular cavity (24d) adapted to accumulate fuel filtered by said first filter element (22).
7 The multistage fuel filter assembly as claimed in claim 4 and claim 5, wherein said first annular cavity (22c) and said second annular cavity (24d) are co-axial.
8 The multistage fuel filter assembly as claimed in claim 1, wherein said top cap (18) comprises at least one opening (18a) for allowing air present in fuel to accumulate in said top cap (18).
, Description:Field of the invention
[0001] This invention relates to a multistage fuel filter assembly in a vehicle.
Background of the invention
[0002] A fuel filter is an essential component in a vehicle. The fuel filter is usually located between a fuel tank and a high pressure pump. The fuel supplied by the fuel tank is filtered by the fuel filter and filtered fuel is supplied to the high pressure pump.
[0003] Usually a single fuel filter filters impurities of varying sizes and also filters water from the fuel. One disadvantage of such a filter is that if one section of the fuel filter is clogged then the whole fuel filter is required to be replaced.

[0004] According to a US patent application number US 8535520 B2, a fuel filter has a coalescent element for separating water from fuel, a prefilter element, a main filter element, and a common central tube, wherein the coalescent element, the prefilter element, and the main filter element are arranged sequentially along the common central tube. A fuel filter arrangement has a housing in which the fuel filter is arranged. The common central tube of the fuel filter is attached to the housing, wherein between the fuel filter and the housing an annular space is formed.

Brief description of the accompanying drawings
[0005] Figure 1 illustrates a multistage fuel filter assembly in a vehicle, in accordance with an embodiment of the present disclosure; and

[0006] Figure 2 illustrates a multistage fuel filter assembly in a vehicle, in accordance with another embodiment of the present disclosure.

Detailed description

[0007] Figure 1 illustrates a multistage fuel filter assembly in a vehicle, in accordance with an embodiment of the present disclosure.

[0008] The multistage fuel filter assembly 100 in a vehicle comprises a housing 12, a top cap 18 fitted to one end of the housing 12 and comprising an air vent knob 26 and a base cap 20 fitted to second end of the housing 12 and comprising a drain plug 28. The multistage fuel filter assembly 100 is further characterized by at least two filter elements, a first filter element 22 enclosed within the housing 12. The first filter element 22 comprising a first base plate 22d fitted to the housing 12 and the first base plate 22d comprising at least one opening 22b in flow communication with a second filter element 24. The second filter element 24 is also enclosed within the housing 12 and located below the first filter element 22. The second filter element 24 comprising a second base plate 24b. The second base plate 24b comprising at least one opening 24c in flow communication with the base cap 20.

[0009] In one embodiment, the housing 12 comprises an inlet path 14 located at an operative top end of the housing 12 and an outlet path 16 located at an operative bottom end of the housing 12. In accordance with another embodiment of the fuel filter the inlet path is located in the top cap 18 and the outlet path 16 located at an operative bottom end of the housing (12). The inlet path 14 facilitates flow of fuel from a fuel tank of the vehicle into the multistage fuel filter assembly. The housing 12 may be made of various materials, for example, metal or plastic. The housing 12 holds the filter elements 22 and 24 together when they are arranged within the housing 12.

[00010] The top cap 18 is fitted at the operative top end of the multistage fuel filter assembly 100. The top cap 18 is removable from the multistage fuel filter assembly 100 so that the filter elements 22 and 24 can be assembled in the housing 12. The top cap 18 also comprises an air vent knob 26 for venting air accumulated in the top cap 18. The air vent knob 26 may be fitted to the top cap using threaded rotary connection. Also, the top cap 18 comprises at least one opening 18a so that air gets accumulated in the top cap 18. The top cap 18 as one component from the multistage fuel filter assembly 100 is shown in Figure 1A.

[00011] The multistage fuel filter assembly 100 also comprises a base cap 20 located at operative bottom end of the multistage fuel filter assembly 100. The base cap 20 is also removable from the multistage fuel filter assembly 100. Usually, the base cap 20 is used for accumulating water present in the fuel. The base cap 20 comprises a drain plug 28 for draining out the water accumulated in the base cap 20.

[00012] The multistage fuel filter assembly 100 is characterized by at least two filter elements, the first filter element 22 and the second filter element 24 of varying filter material. Examples of the filter material include, but are not limited to, ceramic fiber, ceramic foams, wound and knitted fiber, fiber paper, cellular substrate, sintered metal and metal fiber filter.

[00013] The filter elements are placed one on top of other and are enclosed in the housing 12. The filter elements are adapted to filter fuel obtained from a fuel tank of the vehicle. The varying filter material filters impurities in the fuel that are of various sizes. In one example, the filter material of one of the filter element may be such that coarse impurities present in the fuel are filtered and the filter material of another filter element may be such that fine impurities present in the fuel are filtered.

[00014] The first filter element 22 is arranged proximal to the inlet path 14 as shown in Figure 1 and the second filter element 24 is arranged proximal to the outlet path 16 as shown in Figure 1. The first filter element 22 is adapted for filtering coarse impurities present in the fuel and the second filter element 24 is adapted for filtering fine impurities.

[00015] The first filter element 22 as one whole component is shown in Figure 1B. The filter element 22 comprises a first base plate 22d that is fitted to the housing 12 using a first groove in the housing so that the first base plate 22d is press fitted to a first groove in the housing 12. An O-ring is placed between the first groove and the first base plate 22d is used to provide perfect sealing between the inlet cavity 14a and the outlet chamber 16a. The first base plate 22d is used for supporting the filter material 22a of the first filter element 22. The filter material 22a is adapted for filtering coarse impurities present in the fuel. The fuel filtered from coarse impurities get accumulated in a first annular cavity 22c. The first base plate 22d also comprises an opening 22b so that filtered fuel can pass to a second annular cavity 24d of the second filter element 24.

[00016] The second filter element 24 as one whole component is shown in Figure 1C. The second filter element 24 comprises a second base plate 24b that is fitted to the housing 12 using a second groove in the housing 12 so that the second base plate 24b is press fitted to the second groove in the housing 12. An O-ring is placed between the second groove and the second base plate 24b to provide perfect sealing between the outlet chamber 16a and the base cap 20. The second base plate 24b comprises an opening 24c so that fuel gets accumulated in the base cap 20 and in the second annular cavity 24d. The filter material 24a is adapted for filtering fine impurities present in the fuel. Additionally, the filter material 24a also filters the fuel from water as the filter material 24a is water repellant.

[00017] The two filter elements are placed one on top of the other such that first annular cavity (22c) and said second annular cavity (24d) are co-axial.

[00018] The working of the multistage fuel filter assembly 100 is explained in detail with reference to Figure 1 in the following paragraphs.

[00019] Unfiltered fuel from the fuel tank enters into the multistage fuel filter assembly 100 through the inlet path 14. The fuel entering through the inlet path 14 flows into an inlet cavity 14a formed between the first filter element 22 and the housing 12. The fuel accumulated in the inlet cavity 14a flows through a filter material 22a of the first filter element 22. In one example, the filter material 22a of the first filter element 22 is adapted to filter coarse impurities present in the fuel. As the fuel passes through the filter material 22a, the coarse impurities are filtered and the fuel filtered from such coarse impurities is received by the first annular cavity 22c of the first filter element 22.

[00020] Also, fuel that gets accumulated in the inlet cavity 14a contains air bubbles. These air bubbles rise up towards the top cap 18 through the opening18a so that air gets accumulated in the top cap 18. This air can be vented out using the air vet knob 26.

[00021] The fuel received by the first annular cavity 22c flows into the second annular cavity 24d of the second filter element 24 through the opening 22b present in the first base plate 22d. The fuel flowing out through the opening 22b is thus accumulated in the second annular cavity 24d and in the base cap 20. This fuel still has water present in it. Since the density of fuel is lesser than the density of water, water remains in the base cap 20 and the fuel floats on water and thus remains in the second annular cavity 24d.

[00022] The fuel accumulated in the second annular cavity 24d flows through a filter material 24a of the second filter element 24. In one example, the filter material used in the second filter element 24 is adapted to filter fine impurities present in the fuel. Therefore as the fuel flows through the filter material 24a of the second filter element 24, fine impurities present in the fuel are filtered.

[00023] Also, the filter material 24a is such that it is a water repellant material and hence does not allow water present in the fuel to pass through it. Hence, as the fuel passes through the filter material 24a, water continues to remain in the second annular cavity 24d. This water gets accumulates in the base cap 20 through an opening 24c present in the base plate 24b of the second filter element 24. The water accumulated in the base cap 20 is drained out through the drain plug 28.

[00024] The fuel that passes through the filter material 24a of the second filter element 24 gets collected at an outlet chamber 16a formed between the second filter element 24 and the housing 12. The outlet chamber 16a is in flow communication with the outlet path 16 and thus filtered fuel moves out of the multi stage fuel filter element through the outlet path 16. In one example, outlet path 16 may be in flow communication with a high pressure pump.

[00025] Therefore according to the present disclosure, the first filter element 22 and the second filter elements 24 can be arranged one above the other within the housing 12 thereby making the fuel filter assembly modular in nature. The top cap 18 can be removed from the fuel filter assembly for assembling the two filter elements 22 and 24. Because of such modular design, if any one filter element is clogged with impurities then only that filter can be removed from the assembly and can be replaced with a new filter. Hence need for changing the whole filter is not required.

[00026] Figure 3 illustrates a multistage fuel filter assembly 300 in a vehicle, in accordance with another embodiment of the present disclosure.

[00027] In accordance with this embodiment of the multistage fuel filter assembly 300 in Figure 2, comprises a housing 303, at least three filter elements, namely a first filter element 302, a second filter element 304 and a third filter element 306, a top cap 305 fitted to one end of the housing 303 and a base cap 307 fitted to second end of the housing 303. The first filter element 302, the second filter element 304 and the third filter element 306 are modular in nature and are arranged one above the other within the housing 303 of the multistage fuel filter assembly 300. The housing 303 also defines an outlet path 310 for allowing filtered fuel to move out of the multistage fuel filter assembly 300.

[00028] The first filter element 302 comprises a first base plate 302b and is adapted for filtering coarse impurities present in the fuel. The second filter element 304 comprises a second base plate 304b and is adapted for filtering medium size impurities present in the fuel. The second base plate 304b has an opening 304c for allowing fuel to pass through the next stage. The third filter element 306 comprises a third base plate 306b and is adapted for filtering fine impurities present in the fuel. The third base plate 306b comprises an opening 306c for allowing water to get collected in the base cap 307.

[00029] The top cap 305 defines an inlet path 308, an air bubble outlet 305a and an air vent knob 305b. The top cap 305 can be disintegrated from the housing 303 so that the three filter elements can be arranged one above the other within the housing 303. Once all the three filter elements are placed within the housing 303, the top cap 305 can be fixed back into the housing 303. The base cap 307 is also removable and can be fitted to the multistage fuel filter assembly 300 using a press-fit connection.

[00030] Working of the multistage fuel filter assembly 300 is explained in the below paragraphs by referring to Figure 3.

[00031] Unfiltered fuel from the fuel tank flows into a first annular cavity 302a of the first filter element 302 through the inlet path 308 located in the top cap 305. The fuel present in the first annular cavity 302a flows through a filter material of the first filter element 302 thereby filtering coarse impurities present in the fuel. For example, the first filter element 302 filters coarse particles of size greater than 14 microns with 98.5% efficiency. The fuel filtered from the coarse impurities flows downwards to the second filter element 304 through clearance formed between the first filter element 302 and the housing 303.

[00032] Also the flowing downwards to the second filter element 304 may include air bubbles. These air bubbles rise upwards towards the top cap 305 through an air bubble outlet 305a present in the top cap 305. The air bubbles thus get accumulated in the top cap 305. These air bubbles can be vented out through the air vent knob 305b.

[00033] Fuel flowing downwards to the second filter element 304passes through a filter material of the second filter element 304. The second filter element 304 filters the fuel from medium size impurities. For example, the second filter element 304 filters medium size impurities greater than 6 microns with 97% efficiency. The fuel filtered from the medium size impurities flows into a second annular cavity 304a of the second filter element 304. Further, the fuel from the second annular cavity 304a flows through the opening 304c present in the second base cap 304b and gets collected into a third annular cavity 306a and the base cap 307

[00034] The fuel filtered until this stage still has water in it. Since density of water is greater than density of fuel, the water gets collected below at the base cap 307 and the fuel floats on water and gets settled in the third annular cavity 306a. The fuel from the third annular cavity 306a passes through filter material of the third filter element 306 so that fine impurities present in the fuel are filtered. The filter material of the third filter element 306 is also such that it is water repellant and does not allow water present in the fuel to pass through the filter material therefore water present in the fuel remains in the third annular cavity 306a which gets collected in the base cap 307 through the opening 306c in the third base plate 306b. Further the water accumulated in the base cap 307 is drained out through the drain plug 307a.

[00035] The fuel filtered by the filter material of the third filter element 306 gets collected in an outlet cavity 310a formed between the third filter element 306 and the housing 303. The filtered fuel collected in the outlet cavity 310a thus flows out of the multistage fuel filter assembly 300 through the outlet path 310.

[00036] The multistage fuel filter assembly 300 disclosed in this disclosure enables for modular design. The modular design enables each filter element to be removed separately for cleaning process. Also, such a modular design allows replacement of a filter element that is completely clogged. Therefore, instead of replacing the complete fuel filter, only the filter element that is completely clogged can be replaced using such modular design of the fuel filter assembly.

[00037] 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 the type of filter material of the filter element, size of the filter material, shape of the fuel filter assembly are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.