GB2198196A

GB2198196A - Seal Unit

Info

Publication number: GB2198196A
Application number: GB08725528A
Authority: GB
Inventors: Simon George Brown
Original assignee: West & Son
Current assignee: West & Son
Priority date: 1986-10-31
Filing date: 1987-10-30
Publication date: 1988-06-08
Also published as: GB8725528D0; GB8626057D0

Abstract

A seal unit (10) having first and second relatively rotatable members (11, 18). The first member includes an inlet (80) for pressurised fluid and the second member includes an outlet (50) for the pressurised fluid. The first and second members have opposed faces (14, 19) and one of the faces has an annular channel (12) in which a seal element (15) is housed. The seal element projects from the channel to engage sealingly the other of the opposed faces. The members and the seal are arranged to define a flow path between the inlet and the outlet. <IMAGE>

Description

SEAL UNIT The present invention relates to a seal unit, and a seal therefor, for enabling high pressure fluid to be supplied to a rotating member.

According to one aspect of this invention there is provided a seal unit having first and second relatively rotatable members, one of said members including an inlet for pressurised fluid and the other of said members having an outlet for pressurised fluid, said first and second member having opposed faces, one of said opposed faces having an annular channel in which a seal element is housed, the seal element projecting from the channel to engage sealingly the other of said opposed faces, the members and said seal being arranged to define a flow path between said inlet and said outlet.

Preferably, the seal element has first and second axial end faces.

Desirably, biasing means is provided to bias the seal element against the face of the second member. The first axial end face of the seal element may be biased against said face of the second member.

Preferably, the annular channel is provided in the face of the first member. The face of the first member is desirably slightly spaced from the face of the second member.

The seal element is preferably annular and may be located slidingly in the channel. The seal element may be made for a suitable plastics material such as a polyamide.

Desirably, retaining means is provided to retain the first and second members in the slightly spaced position.

The retaining means may comprise a collar which may be threadably secured to the first member. Alternatively, the collar may be secured to the first member by a plurality of bolts. It will be appreciated that any other securing means may be used.

Preferably, the retaining means is provided with a radially inwardly directed annular shoulder which cooperates with a radially outwardly directed annular shoulder on the second member, wherein the shoulders cooperate to prevent the separation of the first and second members.

The seal unit may be adapted to be attached to cutting means. The cutting means may comprise a rotatable cutting head on which at least one cutting member is provided. Preferably, a plurality of cutting members are provided. The or each cutting member may comprise a pick.

The second member may comprise a radially extending outer portion and a radially extending inner portion which may be raised from the outer portion. Preferably, the cutting means is adapted to be received on the inner portion. The cutting means may comprise a cutting head.

The seal unit may be adapted to fit on a drive means. Preferably, the first member is held stationary and the second member can be rotated.

In a first embodiment of this invention a fluid chamber is defined between the first member and the seal element. Desirably the fluid chamber is defined by the bottom of the channel and the second or axial end of the seal element.

When the fluid chamber is pressurised the seal element may be caused to move axially toward the second member to effect a greater degree of sealing.

In this embodiment, the seal element includes a central annular portion at the first axial end face thereof. The central portion may engage sealingly the second member.

The seal element may be provided with at least one bore, and preferably a plurality of bores, to provide fluid communication between the fluid chamber and the second member.

Preferably, the or each- bore is provided in the central annular portion of the seal element.

Preferably, the outlet comprises at least one port and preferable a plurality of ports which may be in registry with the or each bore, such that when the second member is rotated relative to the seal element the or each port sweeps across the or each bore in fluid communication therewith. Desirably, the or each port is provided in the outer portion of the cutting member.

At least one groove may be formed in the seal element between neighbouring bores which groove may be formed in the first axial end face of the seal element, preferably a plurality of grooves are so formed.

Conveniently each groove extends tangentially between the radial inner side of one bore to the radial outer side of the neighbouring bore.

The bores may extend more than half way round the circumference of the seal element. the bores may extend about the entire circumference of the seal element if desired.

In this embodiment, the biasing means comprises at least one spring, and preferably a plurality of springs.

The springs may be spaced circumferentially about the seal element.

In this embodiment the seal element may comprise annular lip portions which may be disposed either side of the central portion. Preferably the lip portions are provided with a plurality of apertures to allow the fluid to pass between the fluid chamber and the gap between the lip portions and the central portions. Thus the pressure on either side of the lip portions can be equalised.

Preferably the lip portions extend further axially than the central portion so that the lip portions are axially compressed by the second member and biased outwardly against the first member.

A plurality of said inlets may be provided to supply fluid to the fluid chamber. It will be appreciated that a single inlet may be used if desired.

Preferably, the or each port can communicate with a respective duct provided in the cutting means to pass fluid to the picks.

A seal may be provided to seal the point of communication of the port and respective duct.

In a second embodiment of the invention, a support means is provided to support the seal element. The support means may comprise a carrier plate on which the seal element is mounted.

The seal element and the support means may be provided with a bore to provide fluid communication between the inlet and the second member.

The first member may be provided with a recess to receive a conduit for the fluid. Preferably, the conduit is also received in the bore. The conduit may comprise a nozzle which preferably, sealingly engages the first member and the seal element to provide a path for the fluid between the inlet and the second member which path is substantially free from leaks.

A groove may be formed in the seal at the first axial end face thereof. The groove may extend slightly over half way round the circumference of the seal. It will be appreciated that the groove may extend substantially all the way round the circumference of the seal.

Preferably the outlet comprises at least one port and preferably a plurality of ports. The or each port is preferably formed in register with the groove so that when the second member is rotated relative to the first member, the or each port may sweep along the groove in fluid communication therewith. Preferably, the diameter of the or each port is substantially the same or slightly greater than the width of the groove.

The seal element may be-provided with at least one recess and, preferably a plurality of recesses, in the second axial end face thereof. The support means may be provided with at least one aperture and preferably a plurality of apertures aligned with the or each recess.

The or each aperture and recess may receive restraining means to restrain the seal element from movement when the second member is rotated relative to the first member.

The restraining means may comprise at least one and preferably a plurality of restraining pins.

The biasing means may comprise spring means.

Preferably, the biasing means comprises a plurality of belleville washers which are conveniently disposed at each restraining pin.

Holding means may be provided to hold the cutting means on the second member. Preferably the holding means comprises a pin, which may be received in a recess in the second member.

The second member may be adapted to engage the cutting means at the inner portion of the second member, and may be adapted to be spaced from the cutting means at the outer portion thereof to limit chatter of the cutting means as it is rotated.

Fluid release means may be provided to release the fluid if any fluid leaks. The fluid release means may comprise at least one release aperture and preferably a plurality of release apertures are provided in the second member.

The or each port can desirably communicate with a respective duct provided on the cutting means. A seal may be provided to seal the point of communication between the duct and its respective port.

According to another aspect of this invention there is provided a seal unit having first and second relatively rotatable members, the first member including an inlet for pressurised fluid and the second member having outlet for the pressurised fluid, the first and second members having opposed faces, wherein the face of the first member has an annular channel in which a seal element is housed, said seal element being provided with at least one recess adapted to receive restraining means to restrain the seal element from rotatory movement, said seal unit further comprising biasing means being provided to bias the seal against the face of the second member, and a groove provided in the seal wherein when the second member is rotated relative to the first member the outlet sweeps along the groove so that the fluid can pass from the first member to the second member.

Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which: Figure 1 is an axial sectional view of a seal unit according to a first embodiment of the present invention; Figure 2 is a sectional view of the unit of Figure 1 taken along line II-II; Figure 3 is an axial sectional view of a seal unit according to a second embodiment of the invention; Figure 4 is a sectional view of the unit of Figure 3 taken along line IV-IV; Figure 5 is an axial view of a seal element according to the second embodiment of this invention; and Figure 6 is a sectional view of the seal element of Figure 5 taken along the line VI-VI.

The unit 10 illustrated in the drawings includes a first annular member in the form of an annular housing 11 which contains an annular channel 12 formed in one axial end face 14 and which defines a seal chamber in which an annular seal element 15 is housed.

Co-axially arranged with the annular housing 11 is a second annular member 18 including an axial end face 19 which is opposed to and slightly spaced from axial end face 14.

The annular housing 11 is provided with a collar 20 which is screw-threadedly connected thereto by a thread 22. The collar 20 is provided with a radially inwardly directed annular shoulder 23 which co-operates with a radially outwardly directed annular shoulder 24 formed on the annular member 18. The shoulders 23, 24 co-operate to prevent axial separation of the annular housing 11 from the end annular member 18 so that the seal unit maintains its integrity when not fitted to machinery until collar 20 is removed. It will be appreciated that collar 20 may be secured to annular housing 11 by other means, for instance bolts.

The seal element 15 is slidably received in the annular channel 12 for axial movement and is biased in one axial direction so that one axial end 30 of the seal engages the axial face 19 of annular member 18 to form a seal therewith. The opposite axial end 32 of the seal element is spaced from the bottom of the channel to thereby define an annular fluid chamber 34.

The seal element 15 includes a central annular portion 40 having an axial end face 41 which sealingly contacts the axial face 19. The central annular portion 40 has formed therein a series of circumferentially spaced axially extending bores 43 passing therethrough and thereby providing fluid communication between the fluid chamber 34 and the axial face 19. One or more ports 50 are formed in the axial end face 19 in registry with the bores 43. In use, the annular member 18 rotates relative to the seal element 15 such that each port 50 sweeps across successive bores 43. Accordingly each port 50 is fed with fluid whilst it is in registry with a bore 43. As shown in Figure 2, a groove 60 is formed in the end face 41 extending circumferentially between each pair of bores 43.Accordingly fluid is also fed to grooves 60 and so as each port 50 passes between each pair of bores 43 it is constantly supplied with fluid. Preferably, as shown, each groove extends tangentially between the radially -inner side of one bore 43 to the radially outer side of the neighbouring bore 43 so as to provide even resistance to wear as the port 50 sweeps across face 41.

It will be appreciated therefore that by suitably selecting the number and position of bores 43 and by connecting selected bores 43 by a groove 61 is is possible to define a desired sequence of feed of fluid to each port 50 for each complete revolution of the annular member 18. In this respect in the embodiment illustrated, a series of bores 43 is provided which extends a little over half the circumference of the seal element. Thus during each complete revolution, each port 50 is fed with fluid for part of the revolution and is starved of fluid for the remainder. Accordingly the outlet communicating with port 50 is intermittently fed with fluid for each revolution. If desired the series of bores 43 may extend about the entire circumference so that the port DO is fed with fluid continuously throughout each revolution.In such a case, the outlet side of the bore 32 may be merged to thereby define an annular channel.

The seal element 15 is biased into face contact with the end face 19 by means of springs 160 spaced circumferentially about the seal element and also, in use, by fluid pressure in the fluid chamber. This bias coupled with the flexibility of the seal element 1D ensures that the end face 41 maintains surface contact about its periphery with axial end face 19 during relative rotation.

On each side of the central portion 40 there is provided an annular lip seal 70. The outer face 71 of each lip seal 70 sealingly engages the adjacent wall of the channel 12. A fluid chamber 72 is defined between each lip seal 70 and the central portion 40 and communicates with fluid chamber 34 via bores 74. In this way the fluid pressure in fluid chambers 34 and 72 are maintained- the same so as not to influence the sealing contact between the lip seals 70 and adjacent wall of channel 12.

Preferably the axial extend of lip seals 70 si slightly greater than central portion 40 such that the end faces 76 are contacted by end face 19 prior to end face 41 so that in use the lip seals 70 are axially compressed and thereby biased outwardly.

The seal unit 10 is suitable for use for supplying pressurised fluid from a stationary member to a rotary member, such as for example a rotary cutting head as used in coal mining. Such cutting heads require pressurised water of say 3,000 psi to be supplied for flushing dirt away from the picks of the head.

Since personnel operate behind such machines water supply to the picks passing by the rear of the machine has to be inhibited. The present unit enables such a supply to be made. In the illustrated embodiment, annular member 18 is attached to the cutting head 100 and has a series of circumferentially spaced ports DO each communicating with a dust 105 which feeds selected picks (not shown).

The annular member 18 has a bore 18a which is received on a shaft (not shown) on which the pick head is located. The shaft extends from a gear box (not shown) and the annular housing 11 is bolted to a bearing housing 106 which in turn is bolted to the gear box housing.

The seal element is preferably made from a suitable plastics material such as a polyamide.

A series of inlet ports 80 are preferably provided in the annular housing for supplying pressurised fluid to the fluid chamber although a single inlet port 80 may be used if desired.

Figures 3, 4, 5 and 6 show a second embodiment of this invention, in which features are the same as those shown in Figures 1 and 2 have been given the same reference numbers.

The seal element 15 is supported by support means in the form of an annular carrier plate 120. The seal element 15 and the carrier plate 120 are slidably received in the annular channel 12.

The seal element 15 and the carrier plate 120 are prevented from circumferential movement about the annular channel 12 by restraining means in the form of a plurality of pins 122. On end of each pin 122 is received in a recess 124 in the seal element 15 and in an aperture 126 in the carrier plate 120 as shown in Figure 4. The other end of each pin 122 is received in a recess 128 in the annular housing 11.

Biasing means in the form of a plurality of belleville washers 130 are provided at each pin 128. The belleville washers 130 bias the seal element 15 slightly beyond the face 14 of the annular housing 11 and into face contact with the end face 19 of the second member 18.

The second member 18 is prevented from axial separation from the annular housing 11 by means of a collar 20 as described above. The collar 20 is secured to the annular housing 11 by a plurality of bolts 132 threadably received in the annular housing 11.

The seal element 15 and the carrier plate 120 are provided with a bore 134. A conduit in the form of a nozzle 136 is provided which sealingly engages at one end thereof the seal element by means of an O-ring seal 138.

Also, the nozzle 136 sealingly engages at the other end thereof the annular housing 11 in a recess 140 by means of an O-ring seal 142.

As shown in Figure 4, a fluid pathway 137 is set up between the inlet 80 and the second member 18 via the nozzle 136 and through the bore 134.

Referring to Figures 5 and 6, the seal element 15 has a groove 144 formed therein. The groove 144 extends from the bore 134 circumferentially around the seal element 15. The groove 144 extends slightly over half way round the circumference of the seal element 15 as shown.

The second annular member 18 comprises an outer annular portion 150 and an inner annular portion 152 raise from the outer portion 150. In the outer annular portion a plurality of ports 50 are formed. The port 50 is wider at the face 154 which is opposite to face 19 on the second member 18.

Each port 50 communicates with a respective duct (not shown) of a cutting head (not shown). Each duct leads to a pick (not shown) so that fluid can be supplied to the pick.

An O-ring seal 156 seals the point of communication between the port 50 and the duct.

Fluid release means in the form of a plurality of apertures 158 are provided to release the fluid if any seal wears out and begins to leak the fluid.

Holding means in the form of a pin 162 is provided to hold the cutting head (not shown) onto the second member 18. the pin 162 is received in a recess 164 in the second member 18.

The cutting head (not shown) is received on the second member 18 so that the cutting head engages the raised inner portion 152 but is slightly spaced from the outer portion 150. This restricts chatter as the second member 18 is rotated. The pin 162 is received in a recess (not shown) in the cutting head to hold the cutting head in place.

The seal unit 10 of this embodiment can be mounted on a shaft (not shown) of drive means (not shown) which passes through the annular housing 11 and the second member 18 to the cutting head. The annular housing 11 is bolted to a bearing housing (not shown) by bolts 170.

This embodiment of the invention will now be described in operation. The cutting head (not shown) is caused to rotate by the drive means. The rotation of the cutting head causes the second member 18 to rotate. As the second member 18 rotates the ports 50 sweep along the groove 144.

Fluid at a pressure of, for example 3,000 psi, is then pumped into the inlet 80. From the inlet 80 the fluid passes into the bore 134 via the nozzle 136. The fluid then passes into the groove 144.

As successive ports 50 sweep along the groove 144, the fluid passes into the ports 50 and into the ducts (not shown) of the cutting head (not shown).

Thus fluid at a high pressure can be transferred from a stationary member to a rotating member without any substantial losses in pressure.

Claims

1. A seal unit having first and second relatively rotatable members, one of said members including an inlet for pressurised fluid and the other of said members having an outlet for pressurised fluid, said first and second members having opposed faces, one of said faces having an annular channel in which a seal element is housed, the seal element projecting from the channel to engage sealingly the other of said opposed faces, the members and said seal being arranged to define a flow path between said inlet and said outlet.

2. A seal unit according to Claim 1 further comprising biasing means to bias the seal element against the face of the second member.

3. A seal unit according to Claim 1 or 2 wherein the face of the first member is slightly spaced from the face of the second member and the annular channel is provided in the face of the first member.

4. A seal unit according to Claim 3 comprising retaining means to prevent axial separation of the first and second members.

5. A seal unit according to Claim 4 wherein the retaining means comprises a collar threadably secured to the first member.

6. A seal unit according to Claim 4 wherein the retaining means comprises a collar secured to the first member by a plurality of bolts.

7. A seal unit according to any of Claims 4 to 6 wherein the retaining means is provided with a radially inwardly directed annular shoulder which cooperates with a radially outwardly directed shoulder on the second member, whereby the shoulders cooperate to prevent axial separation of the first and second members.

8. A seal unit according to any of Claims 3 to 7 wherein a fluid chamber is defined between the first member and the seal element whereby when the fluid is pressurised the seal element is caused to move axia#lly toward the second member to effect a greater degree of sealing.

9. A seal unit according to any of Claims 2 to 8 wherein the biasing means comprises a plurality of springs spaced circumferentially about the seal element.

10. A seal unit according to Claim 8 or 9 wherein the seal element has first and second axial end faces, a central annular portion provided at the first axial end face of the seal element, whereby the central annular portion engages sealingly the second member.

11. A seal unit according to Claim 10 wherein the seal element is provided with at least one bore to provide fluid communication between the fluid chamber and the second member.

12. A seal unit according to Claim 11 wherein the or each bore is provided in the central annular portion of the seal element.

13. A seal unit according to any of Claims 10, 11 or 12 wherein the outlet comprises at least one port in registry with the or each bore such that when the second member is rotated relative to the seal element, the or each port sweeps across the or each bore in fluid communication therewith.

14. A seal unit according to any of Claims 10 to 13 wherein at least one groove is provided in the first axial end face of the seal element between neighbouring bores.

15. A seal unit according to Claim 14 wherein the or each groove extends tangentially between the radial inner side of one bore and the radial outer side of the neighbouring bore.

16. A seal unit according to any of Claims 10 to 15 wherein the seal element comprises annular lip portions disposed either side of the central portion to form a gap between the lip portions and the central portion.

17. A seal unit according to Claim 16 wherein the lip portions are provided with a plurality of apertures to allow the fluid to pass between the fluid chamber and the gap between the lip portions and the central portion whereby the pressure on both sides of the lip portions is equalised.

18. A seal unit according to Claim 16 or 17 wherein the lip portions extend further axially than the central portion so that the lip portions are compressed axially by the second member and are biased outwardly against the first member.

19. A seal unit according to any of Claim 1 to 7 further comprising support means to support the seal element.

20. A seal unit according to Claim 19 wherein the support means comprises an annular carrier plate on which the seal element is mounted.

21. A seal unit according to Claim 19 or 20 wherein the biasing means comprises a spring means.

22. A seal unit according to Claim 21 wherein the spring means comprises a plurality of belleville washers disposed about the circumference of the seal element.

23. A seal unit according to Claim 22 wherein the seal element is provided with at least one recess and the support means is provided with at least one aperture, the or each aperture being aligned with the or each recess whereby the or each recess and aperture can receive restraining means to restrain the seal element from rotatory movement relative to the first member.

24. A seal unit according to Claim 23 wherein the restraining means comprises a plurality of restraining pins.

25. A seal unit according to Claim 24 wherein the belleville washers are disposed about each restraining pin.

26. A seal unit according to any of Claims 19 to 25 wherein the seal element and the support means are provided with a bore to provide fluid communication between the inlet and the second member.

27. A seal unit according to Claim 26 wherein the first member is provided with a recess to receive a conduit for the fluid, said conduit also being received in the bore.

28. A seal unit according to Claim 27 wherein the conduit comprises a nozzle which sealingly engages the first member and the seal element to provide a path for the fluid between the inlet and the second member, so that the path is substantially free from leaks.

29. A seal unit according to any of Claims 19 to 28 wherein the seal element has first and second axial end faces and a groove is provided in the first axial end face which face engages the second member.

30. A seal unit according to Claim 29 wherein the outlet comprises at least one port formed in register with the groove so that when the second member is rotated relative to the first member, the or each port sweeps along the groove in fluid communication therewith.

31. A seal unit according to Claim 30 wherein the diameter of the or each port is substantially the same as, or slightly greater than the width of the groove.

32. A seal unit according to any of Claims 19 to 31 wherein the second member comprises a radially extending outer portion and a radially extending inner portion raised from the outer portion wherein cutting means is adapted to be received on the inner portion.

33. A seal unit according to Claim 32 wherein holding means is provided to hold the cutting means on the second member.

34. A seal unit according to Claim 33 wherein the holding means comprises a holding pin.

35. A seal unit according to any of Claims 32 to 34 wherein the second member is adapted to engage the cutting means at the inner portion of the second member and is adapted to be spaced from the cutting means at the outer portion of the second member.

36. A seal unit according to any of Claims 19 to 35 wherein fluid release means is provided to release the fluid when fluid leaks.

37. A seal unit according to Claim 36 wherein the fluid release means comprises at least one release aperture in the second member.

38. A seal unit having first and second relatively rotatable members, the first member including an inlet for pressurised fluid and the second member having an outlet for the pressurised fluid, the first and second members having opposed faces, wherein the face of the first member has an annular channel in which a seal element is housed, said seal element being provided with at least one recess adapted to receive restraining means to restrain the seal element from rotatory movement, said seal unit further comprising biasing means being provided to bias the seal against the face of the second member, and a groove provided in the seal wherein when the second member is rotated relative to the first member the outlet sweeps along the groove so that the fluid can pass from the first member to the second member.

39. A seal unit substantially as herein described with reference to and as shown in the accompanying drawings.