FILTER

Abstract

A filter comprising a housing defining an inlet, a first outlet and a second outlet, a first filter element arranged between the inlet and the first outlet such that a portion of the fluid that flows into the inlet flows through the first filter element and out of the first outlet, a second filter element arranged between the inlet and the second outlet such that a portion of the fluid that flows into the inlet flows through the second filter element and out of the second outlet, wherein the first filter element comprises a sintered material filter.

Claims

1. A filter comprising: a housing defining an inlet, a first outlet and a second outlet; a first filter element arranged between the inlet and the first outlet such that a portion of the fluid that flows into the inlet flows through the first filter element and out of the first outlet; a second filter element arranged between the inlet and the second outlet such that a portion of the fluid that flows into the inlet flows through the second filter element and out of the second outlet; wherein the first filter element comprises a sintered material filter.

2. The filter according to claim 1, wherein the sintered material filter is a sintered metal filter.

3. The filter according to claim 1 or claim 2, wherein the first filter element provides a first resistance to fluid flow and the second filter element provides a second resistance to fluid flow; wherein the first resistance to fluid flow is lower than the second resistance to fluid flow.

4. The filter according to any of the preceding claims, wherein the inlet and first outlet are arranged on a first side of the housing and the second outlet is arranged on a second side of the housing.

5. The filter according to any of the preceding claims, wherein the housing comprises an opening and a closure configured to releasably seal the housing; wherein the closure defines the second outlet.

6. The filter according to any of the preceding claims, wherein the inlet has substantially the same cross-sectional area as the first and second outlets combined.

7. The filter according to any of the preceding claims, wherein the first filter element is arranged such that fluid flows substantially radially inwardly through the first filter element.

8. The filter according to any of the preceding claims, wherein the filter is configured such that the majority of the fluid which enters the housing through the inlet flows through the first filter and exits the housing through the first outlet.

9. The filter according to any of the preceding claims, wherein the first and second filter elements are configured such that over 85% of the fluid flowing through the filter passes through the first filter element.

10. The filter according to any of the preceding claims, wherein the first filter element is arranged such that fluid can flow from the inlet to the second filter element without passing through the first filter element.

11. The filter according to any of the preceding claims, wherein the first filter element is removable from the housing.

12. The filter according to any of the preceding claims, wherein the first filter may be arranged such that a portion of the fluid approaching the first filter flows across a portion of the surface of the filter before passing through the surface of the filter.

13. The filter according to any of the preceding claims, wherein the first filter element may comprise a filter membrane configured to remove contaminants from the fluid passing therethrough and the filter membrane is arranged to define a convoluted path to maximise the surface area of the filter membrane exposed to fluid.

14. The filter according to claim 13, wherein the filter membrane is concertinaed.

15. The filter according to claim 13 or claim 14, wherein the filtered membrane comprises a woven layered structure.

16. The filter according to any of the preceding claims, wherein the second filter element comprises a compressed fibre filter.

17. The filter according to any of the preceding claims, wherein the filter comprises a bypass valve configured to bypass one of the first and second filter elements in the event of pressure build up in the filter.

18. The filter according to claim 17, wherein the first filter element is toroidal and the bypass valve is located inside the central space defined by the first filter element.

19. The filter according to any of the preceding claims, wherein the filter comprises a biasing member arranged to separate the first and second filter elements, thus providing a separation chamber; wherein the separation chamber is arranged to hold fluid which is to pass through the second filter element.

20. A filter element for installation in a filter according to any of the preceding claims, the filter element being arrangeable between an inlet and a first outlet such that a portion of the fluid that flows into the inlet of the filter flows through the filter element and out of the first outlet, wherein the filter element comprises a sintered material filter.

21. A filter array comprising a plurality of filters, each according to any of claims 1 to 19.

22. A filter array according to claim 20, further comprising a manifold connecting the plurality of filters.

23. A kit of parts for assembling to make a filter according to any of claims 1 to 19 or a filter array according to claim 19.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0106] FIG. 1a is a top view of a filter according to the disclosure;

[0107] FIG. 1b is a side view of the filter of FIG. 1a;

[0108] FIG. 1c is a cross-section view of the filter of FIG. 1a;

[0109] FIG. 2 is an exploded view of a first filter element and bypass valve for use in the filter of FIG. 1a;

[0110] FIG. 3a is a top view of the first filter element;

[0111] FIG. 3b is a side view of the first filter element;

[0112] FIG. 3c is a cross-section view of the first filter element and bypass valve of FIG. 2;

[0113] FIG. 4 is an exploded view of the filter of FIG. 1a;

[0114] FIGS. 5a and 5b are perspective views of a housing for use in the filter of FIG. 1a;

[0115] FIG. 5c is a side view of the housing of FIG. 5a;

[0116] FIG. 6a is a perspective view of a cap for use in the filter of FIG. 1a;

[0117] FIG. 6b is a perspective view of the underside of the cap of FIG. 6b;

[0118] FIG. 7 is a perspective view of a spring cap for use in the filter of FIG. 1a; and

[0119] FIG. 8 is a perspective view of a support disc for use in the filter of FIG. 1a.

DETAILED DESCRIPTION OF THE DRAWINGS

[0120] FIGS. 1a-c depict a filter 8 according to the disclosure. The filter comprises a housing 12, a first filter element 13 and a second filter element 15 (see FIG. 1c). The housing 12 is substantially cylindrical and defines an inlet 18, a first outlet 20 and a second outlet 22. Fluid that flows through the first filter element 13 leaves the filter 8 through the first outlet 20. Fluid that flows through the second filter element 15 leaves the filter 8 through the second outlet 22.

[0121] The filter 8 can be installed in a wider system with the inlet 18, first outlet 20 and second outlet 22 connected to the wider system to receive contaminated fluid and output filtered fluid.

[0122] The filter 8 provides two separate flow paths for fluid being filtered. A first part of the fluid to be filtered flows along the first flow path and the second part of the fluid to be filtered flows along the second flow path. Accordingly, fluid entering the filter is split into two parts, one of which is filtered by the first filter element 13 and the other of which is filtered by the second filter element 15.

[0123] The first filter element 13 has a lower filtration level than the second filter element 15 (i.e. the second filter element 15 can filter out smaller particles/contaminants than the first filter element 13). However, the first filter element 13 has a lower resistance to flow than the second filter element 15, meaning that more fluid can flow through the first filter element 13 than the second filter element 15 in a fixed period. As such, the majority of the fluid entering the filter 8 is filtered by the first filter element 13, which removes the majority of contaminants. A minority of the fluid entering the filter 8 is filtered by the second filter element 15, but this fluid is filtered to a higher degree than that filtered by the first filter element 13.

[0124] Both the first outlet 20 and the second outlet 22 may be connected to the wider system in which the filter 8 is installed such that the filtered fluid (e.g. oil/lubricant) can return to the system. The first outlet 20 may be connected to a high pressure inlet of a high pressure side of the wider system. The second outlet 22 may be connected to a low pressure inlet of a low pressure side of the wider system. The wider system is not shown here, but examples of such systems may be a wind turbine generator lubrication and cooling system.

[0125] One end of the housing comprises a substantially flat surface integrally formed with the curved wall of the cylindrical housing. Although the filter 8 can be used in virtually any orientation, in the following description this surface will be referred to as the lower surface 17. The lower surface 17 comprises the first outlet 20—located on the central axis of the cylindrical housing 12—and the inlet 18, which comprises a plurality of radially disposed ports 18a-h (see FIG. 5a).

[0126] The other axial end of the cylindrical housing 12 (that at the upper end of the housing 12) comprises an opening 19 which is sealable by a cap 10. The cap 10 can be inserted in the opening 19 of the cylindrical housing 12 and rotated to secure the cap 10 relative to the housing 12. FIG. 1a shows the cap 10 which fits into the top of the housing 12, where the cap 10 and the housing 12 mechanically engage. Upon rotation of the cap 10, a seal is formed between the cap 10 and the housing 12 such that fluid cannot leave the housing. The seal between the cap and the housing is provided by a pair of O-ring seals 54 located in grooves around the circumference of the cap 10 (as can be seen in FIG. 1c).

[0127] The cap 10 has a thin cylindrical shape. An opening in the form of a port through and along the central axis of the cap 10 (and hence also the central axis of the housing 12) defines the second outlet 22. The second outlet 22 comprises a nozzle 21 for attachment to a further nozzle, pipe or valve for transporting fluid away from the filter 8.

[0128] The housing 12 in this example is constructed from an aluminium alloy or steel, to enable it to withstand high pressures; it will be understood, however, that other materials may be suitable.

[0129] FIG. 1c shows a cross section through the centre of the filter 8. The first filter element 13 is located in the lower half of the housing 12, adjacent the lower surface 17. The filter 8 comprises a lower seal 32 arranged between the first filter element 13 and the lower surface 17 to support the first filter element 13 and ensure fluid from the inlet 18 cannot flow through the first outlet 20 without flowing through either of the first or second filter element. The lower seal 32 is a rubber ring and forms a seal between the housing 12 and the first filter element 13. The lower seal 32 also acts as a non-return valve, preventing fluid from flowing out of the inlet 18.

[0130] The first filter element 13 is discussed in more detail with reference to FIGS. 2 to 3c.

[0131] FIG. 1c also shows the second filter element 15 positioned above the first filter element 13, adjacent the cap 10. The second filter element 15 comprises a roll of cellulose 16. The cellulose roll 16 comprises a tightly wound roll of thin cellulose sheet—for example a cellulose fibre sheet of 0.5 mm thickness with 500 pleats per linear meter and a 25 micron porosity. The cellulose roll 16 is arranged with its axis aligned with the central axis of the housing 12 and is sized to be a tight fit in the housing 12 in order to prevent fluid from flowing around the roll 16.

[0132] A spring cap 28 is biased against the lower side of the open mandrel 56 of the cellulose roll 16 in order to prevent fluid from flowing through the centre of the open mandrel 56. The spring cap 28 is biased against the second filter element 15 by a spring 24. The spring 24 is arranged between the first filter element 13 and the second filter element 15. The spring 24 urges the first filter element 13 towards the lower surface 17 and the second filter element towards the cap 10. In doing so, the spring 24 forms a separation chamber 50 between the first and second filter elements 13, 15. The separation chamber 50 is a cavity into which fluid may flow before entering the second filter element 15.

[0133] The operation of the filter 8 will now be described with reference to FIG. 1c. Fluid to be filtered enters the filter 8 through the inlet 18 in the lower surface 17 of the housing 12. The fluid travels along the lower side of the first filter element 13 and through a circumferential gap between the first filter element 13 and the housing 12.

[0134] A portion of the fluid flows radially inwardly through the first filter element 13 via a filter membrane 14. In the present example, about 90% of the fluid is forced through the first filter element 14, which filters contaminants such as solid particulates from the fluid. Due to the first filter element's folds there is a large cross sectional area which allows large volumes of fluid to pass through the first filter element 14 when compared to a conventional filtration material. The sintering process used to produce the steel sheet of the first filter element 14 creates a microstructure comprising a high density woven mesh. This is mesh is ideal for capturing small particles and, because of the high surface area provided by the folds, fluid flow does not slow and the pressure in the filter is not increased. The combination of features provides a high efficiency filtration. The 90% of the fluid which has passed through the first filter element 14 then passes through the perforated barrel 26 to the central space where it flows back towards the lower surface 17 and out through the outlet 20.

[0135] The portion of the fluid that does not flow through the first filter element 13 flows upwards and into the separation chamber 50 located between the first and second filter elements 13, 15. Pressure in the separation chamber 50 forces this fluid to flow up through the cellulose roll 16 of the second filter element 15. In the present example, about 10% of the fluid in the housing 12 bypasses the first filter element 14 and flows through the cellulose roll 16 of the second filter element 15, which is capable of capturing moisture particles and other ultrafine particles. This second filtration is more exhaustive and is often not practical to include in conventional filters as it would increase pressure in the filter to unacceptable levels. However, this is not the case in the present filter 8 in which it is combined with the highly efficient sintered metal filter of the first filter element 14. It is thus possible to filter up to 10% of the fluid, such that it is completely uncontaminated, using the second filter element 16 without a pressure increase across the filter.

[0136] Once the fluid passes through the second filter element 16 it passes through the perforations in the support disc 30 and exits the housing 12 through the second outlet 22. In use the second outlet 22 would have a pipe/hose attached to it to return the oil to the system and/or reservoir.

[0137] FIGS. 2, 3a, 3b and 3c depict the first filter element 13 for use in a filter 8 according to the disclosure.

[0138] The first filter element 13 comprises a bracket including an upper plate 34 and a lower plate 40. A filter membrane 14 comprising a sintered metal filter arranged in a folded configuration is located between the upper and lower plates 34, 40. The sintered metal filter is arranged in the shape of a nine-pointed star. Such an arrangement greatly increases the surface area of the filter membrane 14 and increases the maximum flow rate of the first filter element 13. The filter membrane 14 defines an outer and inner diameter. In this example, the outer diameter is roughly equal to that of the upper and lower plates 34, 40. The inner diameter is roughly equal to that of a perforated barrel 26 located inside the inner radius of the filter membrane 14. The perforated barrel 26 supports the filter membrane 14, transfers loads between the upper and lower plates 34, 40 and allows filtered fluid which has passed through the filter membrane 14 to enter the centre of the first filter element to exit the filter 8.

[0139] Inside the first filter element 13 a bypass valve 58 is arranged to bypass the first filter element in the event that the pressure inside the filter 8 passes a threshold value.

[0140] The bypass valve 58 comprises a body 44, a seal 42 and a valve spring 52.

[0141] The valve body 44 is located inside the perforated barrel 26, sandwiched between the upper and lower plates 34, 40. The body 44 comprises a valve inlet 60 at its upper end which is fluidically connectable to and hence is exposed to the pressure of the separation chamber 50. The body 44 comprises a valve outlet 62 towards the lower end and sides of the valve body 44. The seal 42 is located inside the body 44 and is biased by the valve spring 52 upwards, into a closed position, in which it is located adjacent the valve inlet 60 such that it seals the valve inlet 60 and prevents fluid flow therethrough. The valve body 44 has a rim which prevents the valve seal 42 from being pushed completely free of the valve body 44.

[0142] In the event that the filter membrane 14 becomes blocked such that fluid cannot flow therethrough, the pressure in the filter 8 will increase. All of the fluid entering the filter 8 will flow through the circumferential gap between the first filter element 13 and the housing 12 and will enter the separation chamber 50. The pressure in the separation chamber 50 will therefore increase. This will cause a pressure differential across the valve seal 42 and will urge the valve seal 42 against the action of the valve spring 52. Eventually, the pressure will reach a threshold value at which the valve seal 42 will move downwards towards the lower surface 17, against the action of the valve spring 52, thus opening the valve inlet 60. Fluid from the separation chamber 50 can then flow through the bypass valve 58 and out of the first outlet 20. The same process occurs if the second filter element 15 or second outlet 22 becomes blocked, causing an increase in pressure in the separation chamber 50.

[0143] Accordingly, the bypass valve 58 is configured to change the filter 8 into a bypass filter in the event that either one of the first and second filter elements 13, 15 becomes blocked, leading to an increased filter pressure.

[0144] FIG. 4 is an exploded view of the filter 8 of FIG. 1a. The filter 8 may be assembled by locating the lower seal 32 about the first outlet 20 in the lower surface 17 of the housing 12, sitting the first filter element 13 on top of the lower seal 32. The spring 24 and spring cap 28 are located on top of the first filter element 13 and are compressed as the second filter element 15 is moved into position. Finally, the support disc 30 is inserted on top of the second filter element 15. The cap 10 can then be screwed onto the housing 12 to close and seal the filter 8. A base seal 38 is located around the bottom of the lower surface 17 in order to aid in attaching and sealing the filter 8 with the surrounding wider system.

[0145] FIGS. 5a to 5c depict the housing 12 with eight radially disposed ports 18a-18h forming the inlet 18. The first outlet 18 is also shown, at the centre of the lower surface 17 of the housing 12. The other end of the housing 12 can be seen in FIG. 5b and shows a locking thread 46 on the inner wall of the housing 12. The housing thread 46 engages the cap 10 and is used to secure the cap 10 relative to the housing 12.

[0146] The housing has an internal diameter of approximately 86 mm. The first outlet has a diameter of approximately 20 mm. The radially disposed inlets are approximately 8 mm in diameter and positioned around approximately 44 mm pitch circular diameter.

[0147] FIGS. 6a and 6b depict the cap 10 defining the second outlet 22 at its centre. The second outlet is approximately 5 mm in diameter. The cap 10 has a thread 48 which can be seen in FIG. 6b which mechanically engages with the housing 12. The nozzle of the second outlet also has a profiled outer surface for mechanically engaging with a pipe or hose to reconnect the flow with the surrounding system. The o-ring seals 58 can also be seen around the circumference of the cap 10.

[0148] FIG. 7 shows the spring cap 28 which sits between the spring 24 and the second filter element 15. The spring cap is aluminium and is approximately 35 mm in diameter. The spring cap 28 is dimensioned such that it has a protrusion which is substantially similar to the diameter of the mandrel opening 56 in the second filter element 15. Thus when assembled the spring 24 pushes the spring cap 28 against the second filter element 15 and creates a seal between the components.

[0149] FIG. 8 shows the perforated support disc 30 which is positioned between the cap 10 and the second filter element 15. The perforated support disc 30 is fabricated from an aluminium alloy and is approximately 85 mm in diameter and approximately 1.5 mm in thickness. The perforations are circular in cross section and are equally spaced about several pitch circular diameters. There are 32 perforations in this example; however there may be more or less perforations as long as their distribution permits adequate flow.

[0150] The filter is constructed such that the cap 10 can be easily removed and any of the components inside can be replaced or serviced. The second filter element 15 can be periodically replaced. The first filter element 13 is designed such that it should not require replacement but it may be periodically flushed or rinsed with water/cleaning fluid—or replaced, if required.

[0151] Examples according to the disclosure could be constructed from a variety of materials not discussed in the specific embodiments considered above. It may be preferable to construct some or all components from other metals or polymers. The filter components may also be constructed in different sizes to suit a particular application.

[0152] While certain examples have been described, these examples have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel apparatuses described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the apparatuses described herein may be made without departing from the scope of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope of the disclosure.