Filter assembly

Abstract

A filter assembly comprises a filter element, and a mount having at least one port. Each of the filter element and mount has inter-engaging connection formations, where the filter element and mount can be detachably connected to one another. The mount defines a flow path between the port and filter element when the element is connected to the mount and includes a link element which can slide relative to the mount between retracted and deployed positions. The link element has one of a lug and an inclined ramp surface, and the filter element has the other of the lug and ramp surface. The lug and ramp surface form a cam drive where the lug engages the ramp surface as the filter element and mount are assembled, and slide along the surface when the element is rotated to draw the link element out of the mount towards its deployed position.

Claims

1. A filter assembly which comprises a mount having at least one port, and a filter element, each of the filter element and the mount having inter-engaging connection formations by which the filter element and the mount can be detachably connected to one another, and the mount defining a flow path for fluid to flow between the port and the filter element when the filter element is connected to the mount, the filter element comprising a filtration media and an end fitting at one end of the filter element through which a sealing connection is made between the filter element and mount, in which the filtration media defines a hollow chamber, and the end fitting has a tubular bore extending from the end fitting in a direction towards the hollow chamber which defines an axis and is open for fluid flow at the end fitting so that fluid can flow between the mount and the hollow chamber, in which the mount includes a link element which can slide relative to the mount between a retracted position and a deployed position, the link element having one of a lug and an inclined ramp surface which is arranged around the axis, and a wall of the tubular bore of the filter element having the other of the lug and the inclined ramp surface, and in which the lug and the inclined ramp surface form a cam drive in which the lug is capable of engaging the inclined ramp surface as the filter element and the mount are brought together for assembly, and of sliding along the inclined ramp surface when the filter element is rotated relative to the mount to cause the link element to be drawn out of the mount towards its deployed position, and in which the connection formations on the mount are provided on the link element, and the mount and the filter element are configured so that the connection formations on the mount and the filter element are unable to engage one another when the link element is in its retracted position.

2. The filter assembly as claimed in claim 1, in which at least part of the inclined ramp surface extends approximately helically around the one of the filter element and the link element which has the inclined ramp surface.

3. The filter assembly as claimed in claim 1, in which the link element is configured to move axially away from the mount to the deployed position.

4. The filter assembly as claimed in claim 3, in which the link element is moved by rotating the filter element relative to the mount while the lug is engaged with the ramp surface, a shape of the inclined ramp surface causing the lug to be drawn out of the mount.

5. The filter assembly as claimed in claim 1, in which the mount includes an end stop which limits movement of the link element relative to the mount and defines a fully deployed position of the link element.

6. The filter assembly as claimed in claim 1, in which the link element includes a tubular member having a side wall and the lug or the inclined ramp surface is provided on the side wall of the tubular member.

7. The filter assembly as claimed in claim 1, in which the link element comprises a first part on which the lug or the inclined ramp surface is provided, and a second part on which the connection formations are provided, and in which the first and second parts are arranged in fixed relation to each other so they can slide as a single component within the mount.

8. The filter assembly as claimed in claim 1, in which the connection formations comprise a male thread on one of the filter element and the mount, and a corresponding female thread on the other of the filter element and the mount.

9. The filter assembly as claimed in claim 1, in which the mount includes a valve having an open state in which fluid can flow along the flow path and a closed state in which the valve at least partially prevents flow of fluid along the flow path.

10. The filter assembly as claimed in claim 9, in which the link element forms part of the valve.

11. The filter assembly as claimed in claim 10, in which the link element defines part of the flow path when it is in its deployed position and forms and at least partial obstruction to flow of fluid along the flow path when it is in its retracted position.

12. The filter assembly as claimed in claim 10, in which the valve includes a valve member which slides in a bore in the mount through which fluid can flow towards the filter element for filtration or away from the filter element after being filtered.

13. The filter assembly as claimed in claim 12, in which the valve member is acted on by the link element to move the valve between the open and closed states of the valve.

14. The filter assembly as claimed in claim 12, in which the valve member can slide between a retracted position in which the bore in the mount in which the valve member can slide is occluded and a deployed position in which the bore is at least partially open for flow of fluid.

15. The filter assembly as claimed in claim 12, in which the bore in the mount has an opening in its side wall which is at least partially open to flow of fluid when the valve member is in its deployed position, and in which movement of the valve member to its retracted position causes the opening to be closed at least partially by the valve member.

16. The filter assembly as claimed in claim 15, in which the valve member is tubular and has an open end shaped to form a seal with a corresponding surface of the mount when the valve member is in its retracted position.

17. The filter assembly as claimed in claim 1, in which the filter element and the mount have cooperating sealing surfaces, and the sealing surface on the mount is provided on the link element.

18. The filter assembly as claimed in claim 17, in which at least one of the cooperating sealing surfaces is provided by a deformable sealing member.

19. The filter assembly as claimed in claim 17, in which the mount includes a sealing member for forming a seal between the mount and the link element.

20. The filter assembly as claimed in claim 17, in which the link element comprises a first part on which the lug or the inclined ramp surface is provided and a second part, the first and second parts being arranged in fixed relation to each other so that they can slide as a single component within the mount, and in which the sealing surface on the link element is provided in the second part of the link element.

21. The filter assembly as claimed in claim 1, in which the mount includes a spring which acts on the link element to bias the link element towards its retracted position.

22. The filter assembly as claimed in claim 1, in which the filter assembly further includes a housing with a lid, and the filter element is located within the housing, and where the connection formations on the filter element are provided in a central opening of the lid, in which the central opening has an internal circumference, and in which the connection formations extend continuously around the entire internal circumference of the central opening.

23. The filter assembly as claimed in claim 1, in which the connection formations on the filter element define a female thread describing a minimum internal diameter measured from crest to crest of the thread, and in which a part of the wall of the tubular bore in which the other of the lug and the inclined ramp surface is formed describes a maximum internal diameter which is less than the minimum internal diameter described by the female thread.

24. The filter assembly as claimed in claim 1, in which the inclined ramp surface is formed in the wall of the tubular bore.

25. The filter assembly as claimed in claim 24, in which the connection formations on the filter element define a female thread describing a minimum internal diameter which is greater than a maximum external diameter described by the lug of the cam drive, which is provided on the mount.

26. The filter assembly as claimed in claim 1, which includes a sealing member which protrudes from a surface of the end fitting which defines the tubular bore in the end fitting and extends continuously around the tubular bore, the material of the sealing member being more deformable than the material which defines the tubular bore.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Filter elements, filter assemblies, and components thereof are is described below by way of example with reference to the accompanying drawings, in which:

(2) FIG. 1 is an isometric view of a filter assembly.

(3) FIG. 2 an isometric view from below of the mount of the filter assembly shown in FIG. 1 on which a filter element can be mounted.

(4) FIG. 3 is an isometric sectional view through a portion of a filter element which can be used in the filter assembly shown in FIG. 1.

(5) FIGS. 4 to 6 are isometric sectional views of the mount shown in FIG. 2 and the filter element shown in FIG. 3, at initial, intermediate and fully assembled stages.

(6) FIGS. 7 to 9 are isometric sectional views of the filter element shown in FIG. 3 with another mount, at initial, intermediate and fully assembled stages.

DETAILED DESCRIPTION

(7) Referring to the drawings, FIG. 1 shows a filter assembly 2 which includes a housing body 4 and a mount 6. The housing body 4 has a cylindrical wall 7 which defines a hollow space within the body. The housing body includes a base 8. The base includes a drain for liquid contaminants which are separated from the process fluid by means of a filter element within the housing body.

(8) The mount includes first and second conduits 20, 22 for the process fluid. The first conduit 20 communicates with a hollow space within a filter element provided within the housing body. The second conduit 22 communicates with an annular space between the cylindrical wall of the filter element that is provided by the filter media, and the internal surface of the cylindrical wall 7 of the housing body 4. A connection to each of the fluid conduits can be made at any of a number of ports. In the construction shown in FIG. 1, the first fluid conduit has two possible ports 24 and the second fluid conduit has three possible ports 26. Ports which are not used can be blocked using an appropriate blanking piece.

(9) The mount has a fixation flange 10, with holes 28 formed in it in which fixation screws can be inserted to fasten the mount in place for use.

(10) Features of the mount can be understood with reference to FIGS. 2 and 4. FIG. 4 is a sectional view, with the section plane coinciding with the axis of the first fluid conduit 20. The mount has a chamber 100 formed within it and a planar bottom face 101. The chamber is circular. A central port 102 extends between the chamber and the first fluid conduit. A peripheral port 103 extends between the planar bottom face 101 and the second fluid conduit 22.

(11) A link element 104 is fitted in the chamber 100. The link element 104 includes an initiator part 106 and a connector part 108. The connector part is a sliding fit against the cylindrical internal wall of the chamber.

(12) The connector part has a main body 112 which has an outwardly facing groove 114 formed in it. A deformable sealing member 116 is provided in the groove. The main body with the deformable sealing member is a sliding fit against the cylindrical wall of the chamber 100. The connector part has a collar 118 which depends from the main body. The collar has a thread 120 formed on its outer wall. The collar has a shoulder 122 on its inner wall at about the junction between the collar and the main body.

(13) The initiator part of the link element is a tight fit within the collar of the connector part. It has a cylindrical lower part 130 which protrudes from the connector part and an upper part which is provided by a plurality of fingers 132 extending upwardly from the lower part. The fingers can flex radially inwardly and outwardly. Each of the fingers has an outwardly directed barb 134 and an inwardly directed shoulder 138 at its free end.

(14) The initiator part of the link element has four peripheral ledges 136 formed in its outer wall, spaced apart around the periphery of the wall, at about the junction between the upper and lower parts of the initiator part.

(15) Axial movement of the connector part 108 relative to the initiator part 106 is restricted by the peripheral ledges 136 which engage the bottom of the collar 118, and by the outwardly directed barbs 134 on the flexible fingers which engage the shoulder 122 on the collar.

(16) The initiator part of the link element has a pair of outwardly directed lugs 140 at its bottom edge.

(17) The mount includes a support tube 150 for the link element. The support tube 150 if fastened in the central port 102 which extends between the chamber and the first fluid conduit 20, for example by means of an adhesive. The support tube has an outwardly facing flange 152 at its bottom end. The link element is a tight sliding fit on the flange 152 on the support tube so that the interface between the flange and the internal wall of the link element resists loss of a process fluid flowing through the support tube and the link element.

(18) The support tube 150 can be fitted within the fingers 132 of the upper part of the initiator part of the link element. A helical spring 154 is located in the annular space between the fingers and the support tube, which is defined upwardly by the inwardly directed shoulders 138 at the free ends of the fingers and downwardly by the outwardly facing flange 152 at the bottom end of the support tube.

(19) The mount includes a cover plate 156 which fits over the chamber 100. The cover plate has a first opening 158 formed in it through which the initiator and connector parts of the link element can extend. The cover plate has a second opening 160 formed in it which can be aligned with the peripheral port 103 in the mount. The cover plate can be fastened to the mount by means of threaded screws which extend through countersunk holes 162 in the plate into threaded bores in the mount.

(20) Assembling the link component with the mount involves: a. Positioning the connector part 108 in the chamber 100 with the sealing member 116 compressed within the groove 118 by the cylindrical internal wall of the chamber. b. Fastening the cover plate 156 over the chamber 100. c. Fitting the fingers 132 of the initiator part 106 into the collar 118 of the connector part 108. This involves deforming the fingers inwardly until the outwardly directed barbs 134 pass through the collar and can engage the shoulder 122 on the connector part. d. Positioning the spring 154 on the outer wall of the support tube 150. e. Inserting the support tube into the bore within the initiator part so that the end of the support tube is received in the central port 102 in the mount. f. Fastening the support tube in the bore in the mount, for example by means of mating threads or by bonding.

(21) FIG. 3 shows a filter element 200 which has a cylindrical wall 202 provided by filter media. The filter media can include a paper filter layer which is formed by pleating. It can include a layer of a coalescer material such as a coalescer foam. The filter element includes a support core 204, for example provided by a perforated cylinder formed from metal sheet. The filter element has top and bottom end fittings. The top end fitting 206 is shown in FIG. 3. It is connected to an end face of the cylindrical wall of the element. Known techniques for fastening an end fitting to a cylindrical wall of a filtration media include use of an adhesive material and welding.

(22) The top end fitting 206 defines a central bore 208 which communicates with a cavity 210 within the element. A pair of helical ramp surfaces 212 are defined on the wall of the bore.

(23) The bottom end fitting (not shown) of the filter element has features which are similar to those of the top end fitting which enable it to be connected to the opposite end face of the cylindrical wall of the element. The bottom end fitting does not have a central bore and so extends continuously across the end face of the filter element.

(24) The filter element is located within the housing body 4 so that an annular space 220 is defined between the cylindrical wall 202 of the filter element and the internal surface of the cylindrical wall 7 of the housing body 4. The housing body is closed at its top end by means of a lid 222. The lid has a central opening 224. A collar 226 surrounds the central opening. Apertures 228 are formed in a radially outward portion of the collar, and a thread 230 is formed in the wall of the central opening 224. The lid is sealed to the cylindrical wall of the housing body at its periphery. A deformable sealing member in the form of an O-ring 232 is provided around the periphery of the lid for forming a seal between the filter element and a mount when the element is connected to the mount (as described below). The lid is sealed to the central bore 208 in the top end fitting 206 of the filter element at the central opening 224 by means of a deformable sealing member in the form of an O-ring 234. The O-ring has an upwardly facing convex sealing surface which engages the underside of the lid. The O-ring has a radially inwardly facing convex surface which protrudes into the central bore 208.

(25) FIGS. 4 to 6 show the mount shown in FIG. 2 and the filter element shown in FIG. 3 at initial, intermediate and fully assembled stages. As shown in FIG. 4, assembly of the filter element 200 (with the housing body 4) with the mount 6 involves aligning the openings in the lid 222 on the housing body and the central bore 208 in the top end fitting 206 of the filter element with the link element 104. Connecting the filter element 200 to the mount 6 involves moving the filter element 200 relative to the mount 6 in a first direction A along an axis 225 of the filter assembly, shown in FIG. 4. The element is advanced towards the mount until the top surfaces of the lugs 140 on the initiator part of the link element are located axially beyond the helical ramp surfaces 212 on the wall of the bore 208 in the top end fitting.

(26) Rotation of the filter element 200 relative to the mount 6 causes the link element 104 to be drawn out of the chamber 100 in the mount by the cam action of the lugs 140 against the helical ramp surfaces 212. The spring 154 is progressively compressed between the inwardly directed shoulders 138 at the free ends of the fingers 132 and the outwardly extending flange 152 at the bottom end of the support tube 150 as the link element is drawn out of the chamber. The rigid connection between the connector part 108 and the initiator part 106 of the link element 104 means that the connector part 108 is also drawn out of the chamber 100, exposing the thread 120 on the collar 118 of the connector part. This can be seen in FIG. 5.

(27) Continued action of the lugs 140 against the helical ramp surfaces 212 caused by rotation of the filter element causes the filter element to be drawn towards the planar bottom face 101 of the mount so that the thread 120 on the collar 118 of the connector part engages the thread 230 which is formed in the central opening 224 in the lid of the element housing. Continued rotation of the filter element 200 relative to the mount causes the O-ring sealing member 232 which is provided around the periphery of the lid of the element housing to be compressed between the lid and the planar bottom face 101 of the mount as the threaded connection between the lid and the mount tightens. The spring 154 is compressed with the main body 112 of the connector part 108 in contact with the cover plate 156 which closes the chamber 100. The lugs 140 become separated from the helical ramp surfaces 212. The assembly is shown in this state in FIG. 6.

(28) The lugs 140 and the ramp surfaces 212 are arranged so that the link element 104 moves from its retracted position to its deployed position in a second direction B along the axis 225, the second direction being opposite to the first direction A of insertion of the filter element 200. In use, the filter element 200 is moved in the first direction A, towards the mount 6, to bring the filter element and the mount together. The cam action between the lugs 140 and the ramp surfaces 212 then causes the link element 104 to be moved in the second direction B, away from the mount 6, to the deployed position.

(29) As can be seen in FIG. 6, the movement of the connector part 108 out of the chamber 100 results in the circumferential surface of the connector part towards its leading edge being received within the radially inwardly facing convex surface of the O-ring seal 234 which protrudes into the central bore 208 in the filter element, forming a fluid tight seal between the filter element and the connector part.

(30) The wall of the central opening 224 in which the female thread 230 is formed has an internal circumference. As can best be appreciated from the sectional view of FIG. 3, the female thread 230 extends substantially continuously around the entire internal circumference, and so in substantially unbroken fashion around the circumference. This can facilitate manufacture of the thread 230. The female thread 230 describes a minimum internal diameter, which is measured from crest to crest of the thread across a diameter of the bore 208. The part of the wall of the tubular bore 208 in which the helical ramp surfaces 212 are formed describes a maximum internal diameter which is less than the minimum internal diameter described by the female thread 230. In this way, the link element 104 defining the lugs 140 can be inserted axially through the female thread 230 without coming into contact with the thread, and so irrespective of a rotational orientation of the link element relative to the filter element 200. The minimum internal diameter described by the female thread 230 is suitably greater than a maximum external diameter described by the lugs 140 on the link element 104, the maximum external diameter being defined by a circle which intersects with maximum radially outer extents 141 (FIG. 2) of the lugs.

(31) The assembly can be used to filter a fluid when a filter element is connected to the mount in the state shown in FIG. 6. The assembly can be used in an outside-to-inside operating mode in which the fluid to be filtered flows through the wall of the filter element from the outside to the inside. The assembly can also be used in an inside-to-outside operating mode in which the fluid to be filtered flows through the wall of the filter element from the inside to the outside. Operation of the assembly is described below with the fluid flowing through the element wall from the outside to the inside.

(32) A fluid which is to be filtered is supplied to the assembly through one of the ports 26 of the second process fluid conduit 22. The unused ports of the second process fluid conduit are blocked using appropriate blanking pieces. The fluid flows through the peripheral port 103 into the space between the housing lid 222 and the cover plate 156 and bottom face 101 of the mount. It then flows into the space between the top end fitting 206 of the filter element and the lid 222 of the housing through the apertures 228 which are formed in the outward portion of the collar 226. The O-ring seal 234 located between the central bore in the top end fitting 206 and the central opening 224 in the lid isolates the fluid flowing into that space from fluid within the cavity 210 in the element which has been filtered.

(33) The fluid flows to the annular space 220 which is defined between the cylindrical wall 202 of the filter element and the internal surface of the cylindrical wall 7 of the housing body 4, and then through the wall of the filter element. Contaminants in the fluid (for example particulate contaminants and droplets of an immiscible liquid when the fluid is a liquid) are retained within the wall of the filter element. The filtered fluid is then discharged from the wall of the filter element into the central cavity 210 within the element.

(34) Filtered fluid flows the connector part 108 and the central port 102 in the mount and is discharged from the assembly through one of the ports 24 of the first process fluid conduit 20.

(35) The fluid flows through the wall of the filter element into the annular space 220 which is defined between the cylindrical wall 202 of the filter element and the internal surface of the cylindrical wall 7 of the housing body 4. Contaminants in the fluid are separated from the fluid by the layers of filter media which make up the wall of the filter element. Any liquid contaminants which are separated in this way can be discharged from the filter assembly through the drain in the housing base. The use of drains in filter assemblies of this general kind is known.

(36) The fluid which has been filtered by passing through the wall of the filter element flows to the space between the top end fitting 206 of the filter element and the lid 222 of the housing. The O-ring seal 234 located between the central bore in the top end fitting 206 and the central opening 224 in the lid isolates the fluid flowing into the cavity within the filter element from the fluid which has been filtered.

(37) The fluid in the space between the top end fitting 206 of the filter element and the lid 222 of the housing flows out of the space through the apertures 228 which are formed in the outward portion of the collar 226, into the space between the housing lid 222 and the cover plate 156 and the bottom face 101 of the mount. Fluid is discharged from this space through the peripheral port 103 to the second fluid conduit 22.

(38) The flow of the fluid is reversed compared with that described above when the assembly operates in outside-to-inside mode.

(39) FIGS. 7 to 9 show a different mount and a filter element as shown in FIG. 3 at initial, intermediate and fully assembled stages. In this mount, the link element 500 has initiator part 502, a valve member part 504 and a connector part 506. Many of the features of the assembly are common to the assemblies shown in FIGS. 4 to 6 and in FIGS. 7 to 9. The same reference numerals are used for these features.

(40) The connector part 506 of the link element 500 has a main body 510 which is a sliding fit against the cylindrical wall of the chamber 100. The main body has an annular cut out 512 in its outer wall which defines a pocket in which a spring 514 can be received, acting between the cover plate on the cavity 100 and the main body of the connector part. The connector part has a collar 520 which depends from the main body 510.

(41) In the embodiment shown in FIGS. 7 to 9, the initiator and valve member parts 502, 504 of the link element 500 are formed integrally as a single piece, for example by moulding or casting. The diameter of the initiator part is smaller than that of the valve member part. The initiator part is a sliding fit within the collar 520 of the connector part. As with the embodiments shown in FIGS. 4 to 6, a thread 522 is formed on the collar.

(42) The valve member part 504 is a sliding fit in the central port 102 in the mount. The free upper end 524 of the valve member part is shaped to form a seal with an appropriately shaped surface which defines the first conduit 20 for the process fluid when the valve member part is urged into contact with that surface of the first conduit. An O-ring seal 526 is provided in a groove in the outer wall of the valve member part, which provides a seal between the valve member part and the wall of the central port 102 in the mount.

(43) Axial movement of the connector part 506 of the link element relative to the initiator and valve member parts 502, 504 is restricted by means of a tongue 527 on the outer surface of the initiator part which is received in a groove in the inner surface of the collar 520 of the connector part. The initiator part 502 and the connector part 506 therefore move as a single component relative to the mount when they are assembled together. It is an advantage in some situations that they are provided as separate parts because this enables them to be made from different materials. For example, the initiator part can be made from a polymeric material which has the advantages that it allows convenient manufacture by moulding and that a relatively soft material can be used. The connector part can be made form a metal, for example by casting or machining or a combination of the two. The use of a metal has the advantage that a relatively hard material can be used which is not prone to damage, for example because of wear.

(44) A fluid which is to be filtered is supplied to the assembly through one of the ports 24 of the first process fluid conduit 20. The unused ports of the first process fluid conduit are blocked using appropriate blanking pieces. When the mount does not have a filter element connected to it, the upper end 524 of the valve member abuts the matching surface which defines the first conduit 20, forming a seal to that surface. This prevents flow of the process fluid from the first conduit through the central port 102. The mount is shown in this state in FIG. 7, together with a filter element which is the same as the one shown in FIGS. 4 to 6.

(45) As shown in FIG. 7, assembly of the filter element 200 (with the housing body 4) with the mount 6 involves aligning the openings in the lid 222 on the housing body and the central bore 208 in the top end fitting 206 of the filter element with the link element 500. The element is advanced towards the mount until the top surfaces of the lugs 140 on the initiator part of the link element are located axially beyond the helical ramp surfaces 212 on the wall of the bore 208 in the top end fitting.

(46) Rotation of the filter element 200 relative to the mount 6 causes the link element 500 to be drawn out of the chamber 100 in the mount by the cam action of the lugs 140 against the helical ramp surfaces 212, compressing the spring 514. The rigid connection between the connector part 506 and the initiator part 502 of the link element 500 means that the connector part 506 is also drawn out of the chamber 100, exposing the thread 522 on the collar 520 of the connector part. The formation of the initiator part 502 and the valve member part 504 of the link element 500 as one part means that the upper end 524 of the valve member becomes separated from the matching surface which defines the first conduit 20, opening the link element to flow of fluid from the first conduit 20 to the chamber 100. This can be seen in FIG. 8.

(47) Continued action of the lugs 140 against the helical ramp surfaces 212 caused by rotation of the filter element causes the filter element to be drawn towards the planar bottom face 101 of the mount so that the thread 522 on the collar 520 of the connector part engages the thread 230 which is formed in the central opening 224 in the lid of the element housing. Continued rotation of the filter element 200 relative to the mount causes the O-ring sealing member 232 which is provided around the periphery of the lid of the element housing to be compressed between the lid and the planar bottom face 101 of the mount as the threaded connection between the lid and the mount tightens. The spring 514 is compressed with the main body 112 of the connector part 506 in contact with the cover plate 156 which closes the chamber 100. The assembly is shown in this state in FIG. 9.

(48) Use of the filter assembly which is shown in FIGS. 7 to 9 is the same as for the assembly shown in FIGS. 4 to 6. The assembly which is shown in FIGS. 7 to 9 has the added advantage that the engagement of the valve member with the matching surface which defines the first conduit can help to reduce loss of the process fluid from the first fluid conduit when a filter element is not attached to the mount.