GB2513183B

GB2513183B - Rotary coupling

Info

Publication number: GB2513183B
Application number: GB1307105.5A
Authority: GB
Inventors: Moyes Peter
Original assignee: Welleng Science and Technology Ltd
Current assignee: Welleng Science and Technology Ltd
Priority date: 2013-04-19
Filing date: 2013-04-19
Publication date: 2019-11-13
Anticipated expiration: 2033-04-19
Also published as: GB201307105D0; GB2513183A

Description

ROTARY COUPLING

FIELD OF THE INVENTION

The present invention relates to a rotary coupling, and in particular a rotary coupling which permits sealed fluid communication between stator and rotor components of such a coupling.

BACKGROUND TO THE INVENTION

Many industries may require a coupling between stationary and rotating components which facilitates fluid transfer between said components. Such a coupling, which is sometimes referred to as a rotary coupling, hydraulic swivel or rotary union, may be required in vacuum applications, within vehicle clutch systems, within braking systems, in machine tools, in the processing industries such as paper, rubber, textiles and chemical, and the like. A conventional rotary coupling includes a stationary component or housing which includes a port/channel within an inner surface thereof, and a rotating component or shaft mounted within the housing and having a port/channel in its outer surface which is aligned with the port/channel in the housing, thus defining a fluid transfer region between the components. A dynamic seal is provided directly between the stationary and rotating components at the location of the fluid transfer region, thus permitting sealed fluid transfer between the components.

Known rotary couplings traditionally employ rotary lip seals which are spring energised by an integral spring to isolate and retain transmitted fluid within the housing/shaft passage. These seals are conventionally fitted into machined grooves within the inner surface of the housing. In order to machine the grooves during the manufacture process, a deep grooving tool fitted to the end of a long boring bar is used to remove material to form the seal groove. This, however, is problematic as the control over the finished size and tolerance is difficult to achieve, and inspection is extremely difficult if not impossible to complete accurately. Control over size and surface finish of sealing surfaces is crucial to successful rotary seal operation, particularly under high pressures or over long duty cycles.

Furthermore, assembly of the lip seal into the groove requires the rigid lip seal to be malformed into a kidney shape before being forced into the groove and then reformed into a circular form to adopt the shape and form of the groove. This can damage both the seal material and the integral spring within the lip seal. This puts sealing integrity at a serious disadvantage. Also, most, if not all of the lip seals inside rotary couplings have back-up rings, which are also very problematic to fit once the lip seal has been formed into a kidney shape.

Rotary couplings with long outer housings (such as multiport rotary couplings) may be limited in size and thus possibly number of permitted ports due to the fact it is very difficult to achieve tight control while machining.

Further, the assembly and disassembly of lip seals with multiport rotary couplings becomes increasingly problematic with increasing length. It is near impossible to assemble lip seals inside a multiport coupling without the aid of assembly tools, which pose a risk of scratching and damaging critical surfaces. Also, due to the rigidity of the lip seals, disassembly is very difficult requiring tools to dig or pull them out, thus also posing a further risk of scratching or damaging a sealing surface, and also possibly ruining the seals.

Also, axial and rotational stability of the shaft to housing is critical to forming and maintaining seal integrity over the duty cycle. Conventional couplings employ cylindrical roller bearings to maintain a concentric relationship between shaft and housing. However, this does not prevent axial shift of the shaft relative to the housing and can cause axial wear to the lip seal.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a rotary coupling, comprising: a housing having an annular channel on an inner surface thereof and including a fluid passage opening into said channel; a shaft rotatably mounted within the housing and having an annular channel on an outer surface thereof and including a fluid passage opening into said channel, wherein the respective annular channels of the housing and the shaft are axially aligned; and a seal assembly radially interposed between the housing and the shaft at the location of the respective annular channels to provide a sealed fluid connection therebetween, wherein the seal assembly comprises a generally cylindrical seal shell including an annular shoulder projecting from a circumferential surface thereof to define an annular recess extending between the annular shoulder and a first axial end of the seal shell, and a dynamic seal arrangement inserted into the annular recess of the seal shell from the first end thereof.

In use, a fluid may be communicated into an annular channel of one of the housing and shaft via the associated fluid passage, and then transmitted through the seal assembly to be received within the annular channel of the other of the housing and the shaft, and then communicated from said annular channel via the associated fluid passage.

By the provision of a seal shell which includes an annular recess extending from the first end, the dynamic sealing arrangement may be inserted directly into this recess from the first axial end of the seal shell, thus minimising or avoiding any requirement to deform the dynamic seal arrangement during assembly, and avoiding the associated problems with the prior art, such as damage to the seal itself, poor seating of the seal and the like.

Furthermore, by permitting the dynamic seal arrangement to be mounted within a separate seal shell which is interposed between the housing and the shaft, any requirement to form seal grooves directly in the housing and/or shaft is avoided, thus avoiding associated manufacturing issues, such as difficulty in machining/forming, difficulty in inspection, difficulty in achieving required tolerances and the like. Also, as the inner surface of the housing does not need to include grooves to accommodate any dynamic seals, this inner surface of the housing may be readily formed, machined or the like to produce a highly consistent polished bore which may be readily inspected for dimensional tolerance, surface finish and the like.

The provision of the seal shell, and providing an annular recess which extends from one end of this seal shell may permit improved manufacturability, including achieving improved surface finishes, improved and readily measurable tolerances, use of simpler manufacturing tooling and techniques and the like.

The annular shoulder which extends from a circumferential surface of the seal shell may define a stepped profile on said circumferential surface.

The seal shell may be configured to be rotatably fixed relative to one of the housing and the shaft such that the dynamic seal arrangement defines a dynamic seal with the other of the housing and the shaft.

As defined above, an annular shoulder extends from one circumferential surface of the seal shell to define the annular recess for accommodating the dynamic seal arrangement. In this respect the seal assembly may further comprise a static seal arrangement on an opposite circumferential surface of the seal shell. Such a static seal arrangement may be configured to provide a seal between the seal shell and one of the housing and the shaft. Specifically, a static seal arrangement may be located between the seal shell and one of the housing and shaft to which the seal shell is rotationally fixed.

The static seal arrangement may be defined by an interference between the seal shell and one of the housing and the shaft. The static seal arrangement may comprise one or more mechanical seals, such as o-ring seals. The seal shell may define one or more recesses or grooves to accommodate one or more mechanical seals. In one embodiment the static seal arrangement may be defined by both an interference and one or more mechanical seals. In such an arrangement the interference may reduce or eliminate any extrusion gap, thus protecting the mechanical seal(s).

The static seal arrangement may comprise a pair of mechanical seals located on opposing axial sides of the annular channel of one of the housing and shaft.

In one embodiment the seal shell may be rotatably fixed relative to the housing, such that the dynamic seal arrangement defines a dynamic seal against the shaft. In an alternative embodiment the seal shell may be fixed relative to the shaft, such that the dynamic seal arrangement defines a dynamic seal against the housing.

The seal shell may be press-fitted within the housing and rotationally fixed relative thereto.

The seal shell may be press-fitted on the shaft and rotationally fixed relative thereto.

The seal shell may be rotationally fixed relative to one of the housing and the shaft via an interlocking arrangement, such as a splined arrangement, keyed arrangement or the like.

The annular shoulder of the seal shell may extend radially inwardly from the inner surface of said seal shell, such that the defined annular recess is located internally of the seal shell, and between the seal shell and the shaft. In such an arrangement the dynamic seal arrangement may be inserted into the internal annular recess from the first axial end of the seal shell, and thus positioned between the seal shell and the shaft. In this respect, as the internal annular recess extends directly from the first axial end of the seal shell, any requirement to deform the dynamic seal arrangement, for example to reduce its diameter, to become mounted within the internal recess of the seal shell may be avoided or at least minimised.

The annular shoulder of the seal shell may extend radially outwardly from the outer surface of said seal shell, such that the defined annular recess is located externally of the seal shell, and between the seal shell and the housing. In such an arrangement the dynamic seal arrangement may be inserted into the external annular recess from the first axial end of the seal shell, an thus positioned between the seal shell and the housing.

The seal shell may comprise one or more radial ports extending between outer and inner surfaces thereof to provide fluid communication between the respective annular channels in the housing and shaft.

The dynamic seal arrangement may comprise a unitary component, such as a unitary annular component.

The dynamic seal arrangement may comprise multiple components.

The dynamic seal arrangement may comprise one or more rotary lip seals.

The dynamic seal arrangement may comprise a pair of annular seal members arranged within the annular recess in the seal shell to define an annular gap therebetween, wherein said annular gap defines a flow path for fluid being communicated between the housing and the shaft.

The annular seal members may be located on either side of the annular channel of one of the housing and the shaft, thus sealing said channel.

The annular seal members may be located on either side of one or more radial ports extending through the seal shell.

The annular shoulder of the seal shell may be defined by an annular lip, projection or the like.

The annular recess formed in the seal shell may include a profiled surface to facilitate or assist location of the dynamic seal arrangement therein.

The dynamic seal arrangement may be located within the seal shell prior to mounting the seal shell within the rotary coupling, for example prior to fitting the seal shell within the housing or on the shaft. Such an arrangement may permit the assembled seal shell and dynamic seal arrangement to be appropriately inspected prior to fitting within the rotary coupling.

The annular shoulder of the seal shell may project from a cylindrical surface of the seal shell at an end region thereof, in particular from a second axial end thereof which is opposite the first axial end.

The housing may define a plurality of annular channels and associated flow passages, and the shaft may define a corresponding plurality of annular channels and associated flow passages, wherein respective annular channels of the housing and shaft are axially aligned relative to each other. In such an arrangement the seal assembly may be configured to provide sealed fluid communication between respective axially aligned annular channels, thus permitting multiple fluid communication paths between the housing and the shaft.

The seal assembly may comprise a plurality of seal shells and associated dynamic seal arrangements interposed between the housing and the shaft at the location of the axially aligned annular channels to provided sealed fluid communication therebetween. Each seal shell and associated dynamic seal arrangement may be configured similarly, for example as defined above.

The seal shells may be axially stacked, for example one against the other, between the housing and the shaft. In some embodiments a spacer arrangement may be axially located between adjacent seal shells.

The seal assembly may comprise a single seal shell configured to receive a plurality of dynamic seal arrangements aligned with respective opposing annular channels.

In one embodiment a plurality of dynamic seal arrangements may be axially stacked within the annular recess formed by the seal shell.

In one embodiment the annular shoulder of the seal shell may be located intermediate opposing first and second axial ends thereof. In such an arrangement first and second annular recesses may be defined on opposing sides of the annular shoulder, wherein the first annular recess extends between the annular shoulder and the first axial end, and the second recess extends between the annular shoulder and the second axial end. A dynamic seal arrangement may be inserted into each annular recess from an associated axial end of the seal shell.

In certain embodiments the housing may be rotatable and the shaft may be stationary. In other embodiments both the housing and the shaft may be rotatable.

The rotary coupling may comprise a bearing arrangement mounted between the housing and the shaft to permit relative rotation therebetween. The bearing arrangement may comprise a pair of axially separated bearings mounted between the housing and the shaft. More then two bearings may be provided.

The bearing arrangement may be configured to accommodate both radial and axial forces applied between the housing and shaft. The bearing arrangement may be configured to resist relative radial and axial motion between the shaft and the housing. Such an arrangement may minimise any non-uniform radial loading on the dynamic sealing arrangement. Further, such an arrangement may minimise axial wear of the dynamic seal arrangement.

The bearing arrangement may comprise at least one tapered bearing, such as a tapered roller bearing.

The bearing arrangement may comprise a loading arrangement configured to preload the bearing arrangement. Such preloading may be provided in at least one of, and in some embodiments both of radially an axially. This arrangement may permit any radial and/or axial instabilities between the housing and shaft to be minimised, thus minimising undesired radial and/or axial relative motion therebetween.

The loading arrangement may be adjustable such that the bearing preload may be adjustable. The loading arrangement may be infinitely adjustable.

The loading arrangement may be adjustable using a threaded collar arrangement which may engage the bearing arrangement, for example engage a race portion of a bearing, such as a tapered roller bearing. A method for manufacturing a rotary coupling may comprise: providing a housing having an annular channel on an inner surface thereof and including a fluid passage opening into said channel; providing a shaft having an annular channel on an outer surface thereof and including a fluid passage opening into said channel, wherein the shaft is mounted within the housing such that relative rotation between the housing and the shaft is permitted and the respective annular channels are axially aligned; providing a generally cylindrical seal shell which includes an annular shoulder projecting from a circumferential surface thereof to define an annular recess extending between the annular shoulder and a first axial end of the seal shell; inserting a generally annular dynamic seal arrangement into the annular recess of the seal shell from the first end thereof; and mounting the seal shell and dynamic seal arrangement to be interposed between the housing and the shaft at the location of the axially aligned annular channels to provide a sealed fluid connection therebetween

Accordingly, the seal shell and dynamic seal arrangement are mounted as a single preassembled unit.

The seal shell and associated dynamic seal arrangement may be press fitted within the housing. A rotary coupling may comprise: a housing having an annular channel on an inner surface thereof and including a fluid passage opening into said channel; a shaft rotatably mounted within the housing and having an annular channel on an outer surface thereof and including a fluid passage opening into said channel, wherein the respective annular channels of the housing and the shaft are axially aligned; a dynamic seal assembly radially interposed between the housing and the shaft at the location of the respective annular channels to provide a sealed fluid connection therebetween; and a bearing arrangement mounted between the housing and the shaft to permit relative rotation therebetween, wherein the bearing arrangement is configured to be preloaded.

Such preloading may be achieved in an axial direction. Such preloading may be achieved in a radial direction.

Such preloading may minimise instability and undesired motion between the housing and the shaft. This may minimise wear on the seal assembly due to such undesired relative motion.

The bearing arrangement may comprise one or more tapered bearings, such as tapered roller bearings.

According to a second aspect of the present invention there is provided a rotary coupling, comprising: a housing having a plurality of annular channels on an inner surface thereof and including respective fluid passages opening into said channels; a shaft rotatably mounted within the housing and having a plurality of annular channels on an outer surface thereof and including respective fluid passages opening into said channels, wherein the respective annular channels of the housing and the shaft are axially aligned; and a seal assembly radially interposed between the housing and the shaft at the location of the respective annular channels to provide a sealed fluid connection therebetween, wherein the seal assembly comprises a plurality of axially stacked generally cylindrical seal shells each including an annular shoulder projecting from a circumferential surface thereof to define an annular recess extending between the annular shoulder and a first axial end of the respective seal shells, and a dynamic seal arrangement inserted into each annular recess of the seal shells from the respective first ends thereof.

According to a third aspect of the present invention there is provided a seal cartridge for providing a seal between a housing and a shaft of a rotary coupling, comprising: a generally cylindrical seal shell including an annular shoulder projecting from a circumferential surface thereof to define an annular recess extending between the annular shoulder and a first axial end of the seal shell; and a dynamic seal arrangement inserted into the annular recess of the seal shell from the first end thereof, wherein the seal cartridge is configured to be radially interposed between the housing and shaft of the rotary coupling to provide a sealed fluid connection therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a rotary coupling according to an embodiment of the present invention;

Figure 2 is a perspective longitudinal cross-sectional view of the rotary coupling of Figure 1;

Figure 3 is a longitudinal cross-sectional view of the rotary coupling of Figure 1;

Figure 4A is an cross-sectional exploded view of a seal cartridge of the rotary coupling of Figure 1;

Figure 4B is a cross-sectional assembled view of the seal cartridge of Figure 4A; and

Figure 5 is a cross-sectional view of a portion of a rotary coupling according to an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS A perspective view of a rotary coupling, generally identified by reference numeral 10, according to an embodiment of the present invention is illustrated in Figure 1, and an alternative perspective view of the rotary coupling 10, in this case shown in half section, is presented in Figure 2.

The rotary coupling 10 includes a housing 12 and a shaft 14 rotatably mounted in the housing 12 via a pair of tapered roller bearings 13, wherein the shaft 14 includes a flange 16 on one end thereof to permit connection with a required component or infrastructure. The housing 12 includes a number of bores or ports 18 extending from an outer surface thereof and each opening into respective annular channels 20 formed in the inner surface of the housing 12. The shaft 14 also includes a corresponding number of ports 22 which extend axially therethrough from the flange 16, and each opening into respective annular channels 24 formed on the outer surface of the shaft 14. Each channel 20 of the housing 12 is axially aligned with a respective channel 24 of the shaft 14.

The rotary coupling 10 further comprises a seal assembly 26 having three seal cartridges 28 interposed between the housing 12 and shaft 14 to permit sealed fluid communication between the respective pairs of aligned channels 20, 24. In use, a fluid may be communicated through ports 18 and into the respective channels 20 in the inner surface of the housing 12, then through the respective seal cartridges 28 to be received in the respective channels 24 on the outer surface of the shaft 14, and finally through the respective shaft ports or bores 22 to be delivered to a target component or location. A more detailed description of the rotary coupling 10, and in particular the seal cartridges 28, will now be provided with reference to Figures 3, 4A and 4B, wherein Figure 3 is a longitudinal cross-sectional view of the coupling 10, and Figures 4A and 4B show exploded and assembled views, respectively, of an individual seal cartridge 28.

Each seal cartridge 28 includes a generally cylindrical seal shell 30 including an annular shoulder 32 extending from an inner surface thereof to define an annular recess 34 which extends from the annular shoulder 34 and is open at an axial end 36 of the associated seal shell 30. Further, each seal shell 30 includes a plurality of radial ports 38 which, when the seal shell 30 is fitted within the coupling 10, are aligned with an associated pair of channels 20, 24 to permit fluid transfer therebetween.

An outer surface of each seal shell 30 includes a pair of annular grooves 40 on opposing axial sides of the radial bores 38, wherein each groove 40 receives an o-ring 42 for providing a static seal against the inner surface of the housing 12, and on opposing axial sides of an associated annular channel 20. Such a static seal may also be provided by an interference fit between the seal shell 30 and the housing 12. Such an interference fit may minimise or eliminate any extrusion gap therebetween, thus assisting to protect the o-rings 42. A pair of dynamic seals, which in the present embodiment are annular lip seals 44, are inserted into the annular recess 34 of each seal shell 30 from the open axial end 36 thereof. As the lip seals 44 are inserted from the open end 36 of the recess 34, the seals do not need to be deformed, as in prior art arrangements, during assembly, and as such the risk of damaging the seals 44 during assembly is significantly minimised. The inner surface of the seal shell 30 may define a profile to assist with location and retention of the lip seals 44 within the recess 34.

The lips seals 44 are positioned on opposing axial sides of the radial bores 38 of the shell 30, and thus also on opposing axial sides of an associated outer annular channel 24 of the shaft 14 when the cartridge 28 is assembled in the rotary coupling 10. In use, the lip seals 44 bear against the shaft in a rubbing manner when the shaft rotates, thus providing a dynamic seal therebetween.

The seal cartridge 28 is fully assembled and then press-fitted into the housing 14. As such, the seal cartridge 28, and in particular the positioning and quality of the lip seals 44 once mounted on the seal shell 30, may be readily inspected prior to insertion within the housing 14, providing significant advantages over prior art arrangements in which inspection is very difficult to achieve.

In the present embodiment the individual seal cartridges 28 are axially stacked against each other.

The provision of the separate seal cartridge 28 eliminates any requirement to form a seal recess in the inner surface of the housing 12 to accommodate a dynamic seal. As such, the inner surface of the housing may be manufactured to a very high standard, and in general manufacturability is significantly improved. Furthermore, as separate seal cartridges 28 are provided, these may be very readily inspected for tolerances, surface finish and the like.

In the present embodiment the bearings 13 are preloaded by a loading arrangement which includes a loading component 50 which acts against the outer race 13a of one bearing 13, and a loading assembly 52 including first and second rings 52a, 52b, wherein the first ring 52a presses against the inner race 13b of the other bearing. The loading arrangement in the present embodiment is adjustable to permit adjustment of the preload in the bearings 13.

Such preloading of the bearings 13 may minimise any radial and axial instabilities between the housing 12 and the shaft 14, thus minimising any unwanted movements which may otherwise increase wear of the lip seals 44.

Reference is now made to Figure 5 of the drawings in which there is shown a diagrammatic cross-sectional view of a portion of a rotary coupling 110 in accordance with an alternative embodiment of the present invention. Rotary coupling 110 is similar to coupling 10 first shown in Figure 1 and described above, and as such like features share like reference numerals, incremented by 100.

Rotary coupling 110 includes a housing 112 and a shaft 114 rotatably mounted within the housing 114 via bearings (not shown). The inner surface of the housing 112 includes a number of annular channels 120 which receive a fluid via ports (not shown) extending from the outer surface of the housing 112. Similarly, the outer surface of the shaft 114 includes a number of annular channels 124 which receive a fluid from the annular channels 120 of the housing 112, and deliver this fluid via ports (not shown) which extend through the shaft 114, for example axially through the shaft 114. A seal assembly 126 is interposed between the housing 112 and shaft 114 to provide a seal connection between the respective channels 120, 124. The seal assembly 126 includes a seal cartridge 128 which, as in the embodiment described above, may be pre-assembled and then press fitted in the housing 112.

The seal cartridge 128 includes a generally cylindrical seal shell 130 which has an annular shoulder 132 extending from an inner surface thereof. In the present embodiment this annular shoulder 132 is located centrally of the seal shell 130 and thus defines a pair of recesses 134a, 134b extending from opposing open ends 136a, 136b. The seal shell further includes two sets of circumferentially distributed radial ports 138 extending from the outer surface of the seal shell 130 and opening into a respective recess 134a, 134b. Each recess 134a, 134b receives a seal arrangement which are inserted from the respective open ends 136a, 136b, thus allowing the seal arrangements to be inserted without requiring any or any significant deformation.

Each seal arrangement includes a pair of annular lip seals 144 located on opposing axial sides of the respective bores 138, and in rubbing engagement on opposing axial sides of the respective channels to thus establish a dynamic seal against the shaft.

The seal shell 130 includes annular grooves 140 on the outer surface thereof to receive respective o-ring seals 142 for providing a static seal between the seal shell 130 and the housing 112.

It should be understood that the embodiments described herein are merely exemplary and that various modifications may be made thereto. For example, any number of passages between the housing and shaft may be provided. Further, in some embodiments the housing may rotate and the shaft may be fixed. In an alternative embodiment both the housing and shaft may rotate. Also, the seal cartridge may be modified such that the dynamic seal is located externally of the seal shell and thus acts against the housing. In such an arrangement the seal shell may be mounted and fixed to the shaft.

Claims

CLAIMS:

1. A rotary coupling, comprising: a housing having an annular channel on an inner surface thereof and including a fluid passage opening into said channel; a shaft rotatably mounted within the housing and having an annular channel on an outer surface thereof and including a fluid passage opening into said channel, wherein the respective annular channels of the housing and the shaft are axially aligned; and a seal assembly radially interposed between the housing and the shaft at the location of the respective annular channels to provide a sealed fluid connection therebetween, wherein the seal assembly comprises a generally cylindrical seal shell including an annular shoulder projecting from a circumferential surface thereof to define an annular recess extending between the annular shoulder and a first axial end of the seal shell, and a dynamic seal arrangement inserted into the annular recess of the seal shell from the first end thereof.
2. The rotary coupling according to claim 1, wherein the annular shoulder defines a stepped profile on the circumferential surface of the seal shell.
3. The rotary coupling according to claim 1 or 2, wherein the seal assembly further comprises a static seal arrangement on an opposite circumferential surface of the seal shell.
4. The rotary coupling according to claim 3, wherein the dynamic seal arrangement provides a dynamic seal against one of the housing and the shaft, and the static seal arrangement provides a static seal against the other of the housing and the shaft.
5. The rotary coupling according to claim 3 or 4, wherein the static seal arrangement is defined by an interference between the seal shell and one of the housing and the shaft.
6. The rotary coupling according to claim 3, 4 or 5, wherein the static seal arrangement comprises one or more mechanical seals.
7. The rotary coupling according to any preceding claim, wherein the seal shell is rotatably fixed relative to the housing, such that the dynamic seal arrangement defines a dynamic seal against the shaft.
8. The rotary coupling according to any one of claims 1 to 6, wherein the seal shell is rotatably fixed relative to the shaft, such that the dynamic seal arrangement defines a dynamic seal against the housing.
9. The rotary coupling according to any preceding claim, wherein the seal shell is press-fitted within the rotary coupling.
10. The rotary coupling according to any preceding claim, wherein the annular shoulder of the seal shell extends radially inwardly from the inner surface of said seal shell, such that the defined annular recess is located internally of the seal shell, and between the seal shell and the shaft.
11. The rotary coupling according to claim 10, wherein the dynamic seal arrangement is inserted into the internal annular recess from the first axial end of the seal shell, and thus positioned between the seal shell and the shaft.
12. The rotary coupling according to any one of claims 1 to 9, wherein the annular shoulder of the seal shell extends radially outwardly from the outer surface of said seal shell, such that the defined annular recess is located externally of the seal shell, and between the seal shell and the housing.
13. The rotary coupling according to claim 12, wherein the dynamic seal arrangement is inserted into the external annular recess from the first axial end of the seal shell, an thus positioned between the seal shell and the housing.
14. The rotary coupling according to any preceding claim, wherein the seal shell comprises one or more radial ports extending between outer and inner surfaces thereof to provide fluid communication between the respective annular channels in the housing and shaft.
15. The rotary coupling according to any preceding claim, wherein the dynamic seal arrangement comprises one or more seal members.
16. The rotary coupling according to any preceding claim, wherein the dynamic seal arrangement comprises one or more rotary lip seal members.
17. The rotary coupling according to any preceding claim, wherein the dynamic seal arrangement comprises a pair of annular seal members arranged within the annular recess in the seal shell to define an annular gap therebetween, wherein said annular gap defines a flow path for fluid being communicated between the housing and the shaft.
18. The rotary coupling according to claim 17, wherein the annular seal members are located on either side of the annular channel of one of the housing and the shaft.
19. The rotary coupling according to claim 17 or 18, wherein the annular seal members are located on either side of one or more radial ports extending through the seal shell.
20. The rotary coupling according to any preceding claim, wherein the annular shoulder of the seal shell is defined by an annular lip.
22. The rotary coupling according to any preceding claim, wherein the annular recess formed in the seal shell includes a profiled surface to assist location of the dynamic seal arrangement therein.
23. The rotary coupling according to any preceding claim, wherein the dynamic seal arrangement is located within the seal shell to define a seal cartridge prior to mounting said seal cartridge within the rotary coupling.
24. The rotary coupling according to any preceding claim, wherein the annular shoulder of the seal shell projects from a cylindrical surface of the seal shell at a second axial end thereof which is opposite the first axial end.
25. The rotary coupling according to any preceding claim, wherein the housing defines a plurality of annular channels and associated flow passages, and the shaft defines a corresponding plurality of annular channels and associated flow passages, wherein respective annular channels of the housing and shaft are axially aligned relative to each other, and the seal assembly is configured to provide sealed fluid communication between respective axially aligned annular channels.
26. The rotary coupling according to claim 25, wherein the seal assembly comprises a plurality of seal shells and associated dynamic seal arrangements interposed between the housing and the shaft at the location of the axially aligned annular channels to provided sealed fluid communication therebetween.
27. The rotary coupling according to claim 26, wherein the seal shells are axially stacked.
28. The rotary coupling according to claim 25, 26 or 27, wherein a seal shell is configured to receive a plurality of dynamic seal arrangements aligned with respective opposing annular channels.
29. The rotary coupling according to any one of claims 25 to 28, wherein a plurality of dynamic seal arrangements are axially stacked within the annular recess formed by a single seal shell.
30. The rotary coupling according to any preceding claim, wherein the annular shoulder of a seal shell is located intermediate opposing first and second axial ends thereof to define first and second annular recesses on opposing sides of the annular shoulder, wherein the first annular recess extends between the annular shoulder and the first axial end, and the second recess extends between the annular shoulder and the second axial end.
31. The rotary coupling according to claim 30, wherein a dynamic seal arrangement is inserted into each annular recess from an associated axial end of the seal shell.
32. The rotary coupling according to any preceding claim, comprising a bearing arrangement mounted between the housing and the shaft to permit relative rotation therebetween.
33. The rotary coupling according to claim 32, wherein the bearing arrangement comprises a pair of axially separated bearings mounted between the housing and the shaft.
34. The rotary coupling according to claim 32 or 33, wherein the bearing arrangement is configured to accommodate both radial and axial forces applied between the housing and shaft.
35. The rotary coupling according to claim 32, 33 or 34, wherein the bearing arrangement comprises at least one tapered bearing.
36. The rotary coupling according to any one of claims 32 to 35, wherein the bearing arrangement comprises a loading arrangement configured to preload the bearing arrangement.
37. The rotary coupling according to claim 36, wherein the loading arrangement is adjustable such that the bearing preload is adjustable.
38. A method for manufacturing a rotary coupling, comprising: providing a housing having an annular channel on an inner surface thereof and including a fluid passage opening into said channel; providing a shaft having an annular channel on an outer surface thereof and including a fluid passage opening into said channel, wherein the shaft is mounted within the housing such that relative rotation between the housing and the shaft is permitted and the respective annular channels are axially aligned; providing a generally cylindrical seal shell which includes an annular shoulder projecting from a circumferential surface thereof to define an annular recess extending between the annular shoulder and a first axial end of the seal shell; inserting a generally annular dynamic seal arrangement into the annular recess of the seal shell from the first end thereof; and mounting the seal shell and dynamic seal arrangement to be interposed between the housing and the shaft at the location of the axially aligned annular channels to provide a sealed fluid connection therebetween
39. A rotary coupling, comprising: a housing having a plurality of annular channels on an inner surface thereof and including respective fluid passages opening into said channels; a shaft rotatably mounted within the housing and having a plurality of annular channels on an outer surface thereof and including respective fluid passages opening into said channels, wherein the respective annular channels of the housing and the shaft are axially aligned; and a seal assembly radially interposed between the housing and the shaft at the location of the respective annular channels to provide a sealed fluid connection therebetween, wherein the seal assembly comprises a plurality of axially stacked generally cylindrical seal shells each including an annular shoulder projecting from a circumferential surface thereof to define an annular recess extending between the annular shoulder and a first axial end of the respective seal shells, and a dynamic seal arrangement inserted into each annular recess of the seal shells from the respective first ends thereof.
40. A seal cartridge for providing a seal between a housing and a shaft of a rotary coupling, comprising: a generally cylindrical seal shell including an annular shoulder projecting from a circumferential surface thereof to define an annular recess extending between the annular shoulder and a first axial end of the seal shell; and a dynamic seal arrangement inserted into the annular recess of the seal shell from the first end thereof, wherein the seal cartridge is configured to be radially interposed between the housing and shaft of the rotary coupling to provide a sealed fluid connection therebetween.