Filter assemblies and end caps for filter assemblies

Abstract: The filter assembly has a housing (33,36) accommodating a filter element (45). One end cap (10) of the filter element (45) has a generally annular body (11) with support veins (16) projecting from one surface (13). A peripheral flange (21) extends from the edge (15) of the body (11) and is spaced from the outer ends (20) of the veins (16) to allow differential expansion of the flange (21) without undue stress. The flange (21) carries two opposed sets of pegs (27,28) for supporting respective sealing rings (30,31) to allow the flange (21) to seal between parts (34,38) of the housing (33,36).

Description: The invention relates to filter assemblies and end caps for filter assemblies. A known form of filter assembly comprises a housing containing a filter element. The housing has an inlet and an outlet with the inlet feeding fluid to be filtered to the filter element and the outlet flowing filtered fluid from the housing. A commonly used filter element is in the form of a pleated sheet of filter material formed into a hollow cylinder with the fluid being filtered by passage through the filter material. For mounting the filter element in the housing, the filter element is provided with end caps. One end cap is mounted at one end of the filter element and the other end cap is mounted at the other end of the filter element. One end cap seals one end of the filter material and also prevents access to the interior of the filter element. The other end cap closes the other end of the filter material but is provided with a central aperture providing fluid communication with the interior of the filter element. It is known from US-A-4126559 to provide the apertured end cap with angularly spaced flow directing fins lying in respective planes including the axis of the aperture with a generally radially extending annular flange projecting from the radially outer ends of the fins and being clamped between two housing parts together with a seal. The purpose of this is to ensure that any unfiltered fluid that leaks round the end cap drains to the exterior of the housing and does not contaminate the filtered fluid. According to a first aspect of the invention, there is provided an end cap comprising an annular body having inner and outer radially extending faces extending between a central aperture and an outer peripheral edge, a plurality of angularly spaced fins on the said outer face, each fin lying in a respective plane including the axis of the aperture, an annular flange extending from said outer peripheral edge and including a portion extending generally radially relative to said aperture axis, said portion having an inner surface and an outer surface, each said surface carrying mounting means for a seal. According to a second aspect of the invention, there is provided a filter assembly comprising a housing containing a filter element, an end of the filter element carrying an end cap according to the first aspect of the invention with the generally radially extending portion of the flange being clamped between two housing parts. The following is a more detailed description of an embodiment of the invention, by way of example, reference being made to the accompanying drawings in which:- Figure 1 is a cross section through an end cap for mounting in a housing of a filter assembly, Figure 2 is a plan view of one side of the end cap of Figure 1, Figure 3 is a plan view of the other side of the end cap of Figure 1, Figure 4 is a plan view from beneath of an inner sealing ring for mounting on the end cap of Figures 1 to 3 showing radially displaced elongated blind holes, Figure 5 is a partial cross-section through a part of a filter assembly showing an end cap according to Figures 1 to 3 mounted between two housing parts. Referring first to Figures 1 to 3, the end cap indicated generally at 10 is formed from any suitable material. For example, it may be moulded from a plastics material such as polypropylene. The end cap 10 comprises a generally annular body 11 having an inner face 12, an outer face 13, a central circular aperture 14 and a radially outer peripheral edge 15. Eight fins 16 project from the outer face 13 of the body 11 with each fin 16 lying in a respective plane normal to the outer face 13 and including the axis 17 of the aperture 14. Each fin 16 has an angled inner edge 18 followed by a backwardly sloping upper edge 19 and an outer edge 20 extending generally normal to the outer face 13. The outer edge 20 terminates radially inwardly of the outer peripheral edge 15 of the body 11. An annular flange 21 extends from the outer peripheral edge 15 of the body 11. The flange 21 has an initial portion 22 extending in a direction generally normal to the outer face 13 and parallel to the aperture axis 17 and to the outer edges 20 of the fins 16. The flange 21 then has an outwardly flared portion 23 followed by a radially extending portion 24. The radially extending portion 24 has an outer surface 25 and an inner surface 26. The outer surface 25 is provided with eight equiangularly spaced pegs 27 best seen in Figure 2. Each peg 27 is in angular register with one of the fins 16. The inner surface 26 is provided with twelve equiangularly spaced pegs 28 with every fourth peg being in angular register with a fin 16. The pegs 28 on the inner surface 26 are positioned radially inwardly of the pegs 27 on the outer surface. In addition, the pegs 28 on the inner surface 26 have a smaller diameter than the pegs 27 on the outer surface 25. As seen in Figure 5, each surface of the radially extending portion carries a respective sealing ring 29,30. As also seen in Figure 5, the outer sealing ring 29 is of generally semi-circular cross-section. The inner sealing ring 30 is generally semi-circular and may have short extended parallel side portions. The sealing ring 29 on the outer surface 25 is provided with angularly spaced blind locating holes 31 that have a slight interference fit with the associated pegs 27 to hold the sealing ring 29 firmly on the outer surface 25. In contrast, the inner sealing ring 30 is provided with radially displaced elongated blind holes 32 that engage the pegs 28 on the inner surface 26. These are best seen in Figure 4. The purpose of the radially displaced elongated blind holes 32 will be described below. The different diameters and numbers of the pegs 27, 28 ensure that the sealing rings 29,30 cannot be fitted incorrectly. In use, the end cap 10 is fitted to an end of a suitable filter element. One form of suitable filter element 45, not seen in Figure 5, comprises a corrugated filter material 46 formed into a generally annular shape around a central core 47 and with a cage 48 around the exterior surface. One end of the generally cylindrical shape so formed is closed by a flat plate end cap 49 and the other end is attached to the end cap 10. The attachment is by connection between the inner face 12 and the pleated filter material 46. The connection may be by gluing or welding or any other suitable process. The filter element 45 so formed is then mounted in a housing shown in Figure 5. With reference to that Figure, the housing comprises a housing body 33 which is generally cylindrical and which is provided at one end with an inlet 50. The other end of the housing body is provided with a generally radially outwardly extending flange 34 formed with an annular concave recess 35. The housing also includes an outlet member 36 which is generally cylindrical in shape with a passage 37 passing through the member 36. One end of the outlet member 36 is provided with an upstream mounting flange 38 and the other end of the outlet member 36 is provided with a downstream mounting flange 39. The upstream mounting flange 38 has a flange surface 40 provided towards its outer edge with an annular concave groove 41. The portion of the flange surface 40 leading to the passage 37 is provided with a frusto conical bevel 42. The end cap 10 and the remainder of the associated filter element are lowered into the first housing part 33 until the inner surface seal 29 rests in the recess 35 in the flange 34 on the first housing part 33. The presence of the radially displaced elongated blind holes 32 ensures that the sealing ring 29 can move radially to locate housing parts 33 of differing diameters. The outlet member 36 is then placed over the open end of the first housing part 33 so that the groove 41 receives the outer surface sealing ring 29. The upper edges 19 of the fins 16 engage the bevel 42 on the flange surface 40. The upstream mounting flange 38 and the first housing part flange 34 are then clamped together to compress the sealing rings 29,30. Fluid to be filtered is supplied to the housing through the inlet. The fluid passes to the exterior of the filter element 45 and is filtered through the filter element 45. The filtered fluid then leaves the interior of the filter element 45 through the aperture 14 in the end cap 10 and through the passage 37 in the outlet member. If there is any leakage of unfiltered fluid past the inner surface seal 30, such leakage will drain to the exterior of the housing. This prevents contamination of the filtered fluid by such leakage. The eight fins 16 give uniform support to the body 11. This is particularly important while the filter assembly is being steamed up to 140°C since it minimizes deflection of the body 11 by the engagement of the upper edges 19 of the fins 16 on the bevel 42 on the flange surface 40. In addition, the fins 16 are spaced from the flange 21. This allows differential expansion of the flange faces 25,26 relative to the housing while avoiding stressing the flange 21. The two sealing rings 29,30 provide upstream and downstream sealing without allowing unfiltered fluid to contaminate filtered fluid or vice versa. The presence of the pegs 27,28 at differing diameters prevents the sealing rings 29,30 being incorrectly assembled. In addition, the radially displaced elongated blind holes 32 allow variations in the diameter of the centre line of the recess 35 to be accommodated.

Claims: An end cap (10) comprising an annular body (11) having inner and outer radially extending faces (12,13) extending between a central aperture (14) and an outer peripheral edge (15), a plurality of angularly spaced fins (16) on the said outer face (13), each fin (16) lying in a respective plane including the axis (17) of the aperture (14), an annular flange (21) extending from said outer peripheral edge (15) and including a portion (24) extending generally radially relative to said aperture axis (17), said portion (24) having an inner surface (26) and an outer surface (25), each said surface carrying mounting means (27,28) for a seal. An end cap (10) according to claim 1, wherein each fin (16) includes a radially outer edge (20) terminating radially inwardly of the outer peripheral edge (15) of the body (11), said annular flange (21) having a portion (22) extending from the body (11) in a direction generally parallel to the aperture axis (17), said radial portion (24) extending from said portion (22). An end cap (10) according to claim 1 or claim 2, wherein at least one of said mounting means comprises a plurality of pegs (27,28) extending from the associated surface (25,26) and angularly spaced around the associated surface (25,26). An end cap (10) according to claim 3, wherein the pegs (27,28) are equi-angularly spaced around the associated surface (25,26). An end cap (10) according to claim 3 or claim 4, wherein each surface (25,26) is provided with a respective plurality of pegs (27,28), each peg (27,28) of each plurality having the same radius from the axis (17) of the aperture (14) as the remaining pegs (27,28) of the plurality. An end cap (10) according to claim 5, wherein the radius of one plurality of pegs (27,28) is different from the radius of the other plurality of pegs (27,28). An end cap (10) according to any one of claims 3 to 6, wherein each peg (27,28) is generally circular in cross-section. An end cap (10) according to claim 7, when dependent on claim 6, wherein the diameters of the pegs (27,28) of one plurality of pegs are the same and the diameters of the pegs of the other plurality of pegs (27,28) are the same. An end cap (10) according to claim 8, wherein the peg diameter of one plurality is different from the peg diameter of the other plurality. An end cap (10) according to any preceding claim, in combination with two seals (29,30), one seal (29,30) being carried by the mounting means (27,28) on one surface (25,26) and the other seal (29,30) being carried by the mounting means (27,28) on the other surface (25,26). An end cap (10) according to claim 10, when dependent on any one of claims 3 to 9, wherein each seal (29,30) is generally annular and includes an angularly spaced plurality of holes (31,32) which receive the pegs (27,28) of the associated surface (25,26). An end cap (10) according to claim 11, wherein the pegs (27) are an interference fit in the associated holes (31). An end cap (10) according to claim 11, wherein the holes (32) are radially elongated to accommodate variations in the radii of the associated pegs (28). An end cap (10) according to any one of claims 5 to 9, wherein one surface (26) carries more pegs (27,28) than the other surface (25). A filter assembly comprising a housing having two parts (33,36) and containing a filter element (45), an end of the filter element (45) carrying an end cap (10) according to any one of claims 1 to 14 with the radially extending portion (24) of the flange (21) being clamped between the two housing parts (34,38). A filter assembly according to claim 15, wherein the end cap (10) is in accordance with claim 10 or any claim appendant thereto, wherein the housing parts (34,38) bear against respective seals (29,30) to clamp the seals (29,30) between the housing parts (34,38) and the radially extending portion (24) of the flange.

Inventors: BUTTERY ROGER ALEXANDER, GUTMAN RICHARD GUY, SMITH KARL SCOTT, BUTTERY, ROGER ALEXANDER, GUTMAN, RICHARD GUY, SMITH, KARL SCOTT
Applicants: PALL CORP, PALL CORPORATION
Application year: 1996
Main classification: B01D35
IPC codes: B01D27, B01D29, B01D35