Abstract:
A rotary seal member, assembly and associated methods for use in a hydraulic rotary swivel are disclosed. The hydraulic rotary swivel includes a first part and a second part rotatable relative to each other. The rotary seal member is positioned between the first part and the second part and can be adapted to be securely retained in a corresponding retaining groove which may be formed in either one of the first part and the second part. In a preferred embodiment, the rotary seal member had an elongate body forming a ring, and has at least one protuberance formed along its length which fits into a cooperating depression formed along the retaining groove. In use, the protuberance and corresponding depression are coupled and cooperate to substantially prevent the rotary seal member from rotating within the retaining groove.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to seal members, assemblies and methods, and in particular rotary seal members, assemblies and methods for a hydraulic rotary swivel.  
       BACKGROUND  
       [0002]     Rotary swivels are often used in applications and equipment requiring rotation of one part relative to another (either continuous rotation in a single direction, or reciprocating rotation in two directions). Such rotary swivels may be found, for example, in heavy lifting and cutting equipment used in the mining and forestry industries. There are also many other industries and applications in which rotary swivels are used, such as in the oil and gas industries. Lifting and/or cutting equipment typically have an upper part that may include a hydraulic lifting or cutting arm and an operator&#39;s cab, for example, which is required to swivel or rotate at a swivel connection in relation to a supporting base frame which typically supports a hydraulic fluid pump and sump. Often it is necessary to be able to pass a pressurized fluid such as hydraulic fluid, through the rotating swivel, so that equipment can be operated. For example, to be able to operate a lifting and/or cutting arm, pressurized hydraulic fluid must pass through the rotary swivel from a hydraulic pump to the arm. In order to operate such heavy equipment, the hydraulic swivels in these machines may be required to handle a wide range of hydraulic pressures, ranging from about 50 psi up to 5000 psi or more.  
         [0003]     In some applications, a requirement for a period of continuous rotation or reciprocating rotation precludes the use of hydraulic hoses to facilitate the passage of processing of hydraulic fluid through the rotary swivel. Also, the wide range of hydraulic pressures required for certain applications may make the use of hydraulic hoses impractical. In such a case, as known in the art, rotary swivels with integrally formed passages (hereinafter referred to as “hydraulic rotary swivels”) many be used in place of hydraulic hoses. For example, U.S. Pat. No. 6,007,105 issued to Dietle et al. (“Dietle”) discloses a “swivel seal assembly” having “staged” rotary seal members that in part define sealed compartments or cavities in a space formed between an outer housing and an inner cylinder, the housing and cylinder being rotatable relative to each other. The sealed compartments and associated channels in Dietle are designed to support high-pressure fluid communication.  
         [0004]     In some known designs, a rotary seal member is used together with an energizer member (e.g. a resiliently deformable o-ring) which is designed to deform under pressure, and urge the rotary seal member against an opposing sealing surface. These rotary seal members and energizer members together may define seals used to compartmentalize hydraulic fluids in “staged” compartments or cavities formed between the housing and the inner cylinder.  
         [0005]     While known rotary seal member designs such as those described above are generally functional, due to the severe operating conditions found in some applications, the seal members and/or the associated energizer members may rapidly wear down and the seal may fail.  
         [0006]     An improved rotary seal member and assembly design which may extend the operational life of a hydraulic rotary swivel by reducing the occurrence of such seal failures is therefore desirable.  
       SUMMARY  
       [0007]     A rotary seal member, assembly and associated methods for use in a hydraulic rotary swivel are disclosed. The hydraulic rotary swivel includes a first part and a second part rotatable relative to each other. The rotary seal member is positioned between the first part and the second part and can be adapted to be securely retained in a corresponding retaining groove which may be formed in either one of the first part and the second part. In a preferred embodiment, the rotary seal member had an elongate body forming a ring, and has at least one protuberance formed along its length which fits into a cooperating depression formed along the retaining groove. In use, the protuberance and corresponding depression are coupled and cooperate to substantially prevent the rotary seal member from rotating within the retaining groove.  
         [0008]     In an embodiment, a corresponding energizer member may be used together with the rotary seal member, and in this case the coupling of the protuberance and corresponding depression will maintain the rotary seal member in a stationary position relative to the energizer member.  
         [0009]     The inventors have recognized that a significant proportion of seal failures in hydraulic rotary swivels are caused by rotary seal members undesirably rotating within their corresponding retaining grooves. Such undesirable rotation may cause significant friction between the rotary seal member and a part or surface not designed to sustain such dynamic friction. For example, when an energizer member is used together with the rotary seal member, these members are designed to remain stationary relative to each other. If subjected to frictional forces for which it is not designed, the energizing member and seal may rapidly degrade and disintegrate in the retaining groove, causing seal failure, and possible blockage of channels and orifices connected to the affected compartments by the disintegrating energizing member.  
         [0010]     Advantageously, by practicing the teachings of the present invention, the likelihood of a seal failure resulting from the above identified problem can be significantly reduced.  
         [0011]     In a first aspect of the invention, there is provided a rotary seal member for forming a seal in a hydraulic rotary swivel, said hydraulic rotary swivel including a first part and a second part rotatable relative to each other in at least one direction and said first part and said second part each having a surface, said surface of said first part opposing the surface of said second part at an interface therebetween, said opposing surfaces of said first and second parts being separated by a gap, said rotary seal member comprising: 
        (a) an elongated annular body forming a closed ring and being positioned at said interface in said gap between said first part and said second part to provide a seal between said first part and said second part, said elongated body being adapted to be retained in a corresponding annular shaped retaining groove formed in said surface of one of said first part and said second part to engage at said interface said opposing surface of the other of said first part and said second part so as to provide said seal;     (b) at least one protuberance formed on said elongate body, said at least one protuberance being adapted to fit within a corresponding depression formed in a surface of said one of said first part and said second part,     wherein, during operation of said rotary swivel to rotate said first part and said second part relative to each other, the interaction of said at least one protuberance and said corresponding depression assists in substantially preventing rotation of said elongated body relative to said annular retaining groove in at least one direction.        
 
         [0015]     Advantageously, by practicing the teachings of the present invention, the likelihood of a seal failure resulting from the above identified problem can be significantly reduced.  
         [0016]     In an embodiment, said corresponding depression is formed along a surface of said retaining groove.  
         [0017]     In another embodiment, said elongated body forming said ring further includes an energizer member receiving surface and a sealing surface.  
         [0018]     In another embodiment, said elongate body of said rotary seal member has first and second sides, and at least one protuberance extends laterally from at least one of said first and second sides.  
         [0019]     In another embodiment, said elongate body forming said ring further includes an energizer member receiving surface and a sealing surface.  
         [0020]     In another embodiment, said energizer member receiving surface of said elongate body is adapted to receive an energizer member placed in said retaining groove.  
         [0021]     In another embodiment, said sealing surface of said elongate body is adapted to slideably contact said opposing surface formed by the other of said first part and said second part.  
         [0022]     In another embodiment, said at least one protuberance and said corresponding depression cooperate to retain said rotary seal member in said retaining groove in stationary contact with said energizer member.  
         [0023]     In another embodiment, said energizer member is a resiliently deformable o-ring.  
         [0024]     In another embodiment, said at least one protuberance extending laterally from at least one of said first and second sides is less than the thickness of said rotary seal member.  
         [0025]     In another embodiment, said at least one protuberance is adjacent said sealing surface.  
         [0026]     In another embodiment, said elongate body has a plurality of protuberances formed thereon, and said retaining groove has corresponding depressions.  
         [0027]     In another embodiment, said plurality of protuberances are substantially evenly spaced on said elongate body.  
         [0028]     In another embodiment, said one of said first part and said second is a cylinder member housed within and which encircles the other of said first part and second part, and said other part is an outer housing surrounding said inner cylinder.  
         [0029]     In another embodiment, said one of said first part and said second is a first cylinder member having a generally flat annular end surface and having said annular groove formed therein, and wherein the other of said first part and said second part is a second cylinder member having a generally flat annular end surface, said first and second cylinders being in longitudinal alignment such that said annular end surfaces of said first and second cylinders form said opposing surfaces at said interface.  
         [0030]     In a second aspect of the invention, there is provided a rotary seal assembly for a hydraulic rotary swivel, said hydraulic rotary swivel including a first part and a second part rotatable relative to each other in at least one direction and said first part and said second part each having a surface, said surface of said first part opposing the surface of said second part at an interface therebetween, said opposing surfaces of said first and second parts being separated by a gap, said rotary seal assembly comprising: 
        (a) an annular rotary seal member comprising an elongate body forming a closed ring and being positioned at said interface in between said first part and said second part to provide a seal, said elongate body having at least one protuberance formed thereon;     (b) an annular retaining groove formed in one of said first part and said second part, said retaining groove being adapted to receive said rotary seal member therein, said retaining groove being formed in one of said first part and said second part to engage an opposing surface formed by the other of said first part and said second part at said interface, said one of said first part and said second part having at least one depression corresponding to and cooperating with said at least one protuberance such that, during operation of said rotary swivel, the interaction of said at least one protuberance and said corresponding depression assists in substantially preventing rotation in at least one direction of said rotary seal member in said annular retaining groove.        
 
         [0033]     In an embodiment, said first part is an inner cylinder and said second is an outer housing, said inner cylinder and said outer housing having a substantially cylindrical interface and a common central axis of rotation.  
         [0034]     In another embodiment, said one of said first part and said second is a cylinder member housed within and which encircles the other of said first part and second part, and said other part is an outer housing surrounding said inner cylinder.  
         [0035]     In another embodiment, said first part and said second part are rotatable relative to each other about longitudinal axes which are parallel to each other.  
         [0036]     In another embodiment, said first part and said second part are rotatable about a common longitudinal axis.  
         [0037]     In another embodiment, said first part and said second part are rotatable relative to each other about longitudinal axes which are parallel to each other.  
         [0038]     In another embodiment, said first part and said second part have a common longitudinal axis of rotation.  
         [0039]     In another embodiment, said outer housing is fixed to a frame and said inner cylinder rotates relative to said outer housing.  
         [0040]     In another embodiment, one of said first part and said second is a first cylinder member having a generally flat annular end surface and having said annular groove formed therein, and wherein the other of said first part and said second part is a second cylinder member having a generally flat annular end surface, said first and second cylinders being in longitudinal alignment such that said annular end surfaces of said first and second cylinders form said opposing surfaces at said interface.  
         [0041]     In a third aspect of the invention there is provided a hydraulic rotary swivel, said hydraulic rotary swivel including a first part and a second part rotatable relative to each other in at least one direction and said first part and said second part each having a surface, said surface of said first part opposing the surface of said second part at an interface therebetween, said opposing surfaces of said first and second parts being separated by a gap, said hydraulic rotary swivel including: 
        at least one rotary seal assembly, each rotary seal assembly comprising:     (a) an annular rotary seal member comprising an elongate body forming a closed ring and being positioned at said interface in between said first part and said second part to provide a seal, said elongate body having at least one protuberance formed thereon;     (b) an annular retaining groove formed in one of said first part and said second part, said retaining groove being adapted to receive said rotary seal member therein, said one of said first part and said second part having at least one depression corresponding to and cooperating with said at least one protuberance such that, during operation of said rotary swivel, the interaction of said at least one protuberance and said corresponding depression assists in preventing rotation of said rotary seal member in said annular retaining groove in at least one direction.        
 
         [0045]     In an embodiment, said hydraulic rotary swivel further comprises first and second rotary seal assemblies and wherein said first and second rotary seal assemblies define a sealed compartment between said first part and said second part.  
         [0046]     In another embodiment, said first part is an inner cylinder and said second is an outer housing, said inner cylinder and said outer housing having a substantially cylindrical interface and a common central axis of rotation.  
         [0047]     In another embodiment, said one of said first part and said second is a cylinder member housed within and which encircles the other of said first part and second part, and said other part is an outer housing surrounding said inner cylinder.  
         [0048]     In another embodiment, said one of said first part and said second is a first cylinder member having a generally flat annular end surface and having said annular groove formed therein, and wherein the other of said first part and said second part is a second cylinder member having a generally flat annular end surface, said first and second cylinders being in longitudinal alignment such that said annular end surfaces of said first and second cylinders form said opposing surfaces at said interface.  
         [0049]     In a fourth aspect of the invention, there is provided a method of adapting a retaining groove in a hydraulic rotary swivel to receive a rotary seal member, said hydraulic rotary swivel including a first part and a second part rotatable relative to each other and having a common interface, said rotary seal member being positioned at said interface in between said first part and said second part to provide a seal, said retaining groove being formed in one of said first part and said second part and being adapted to receive said rotary seal member therein, said method comprising: 
        (i) identifying the size, shape and position of a protuberance provided on said rotary seal member;     (ii) for each said protuberance identified in (i), forming a corresponding depression along said retaining groove, each said depression corresponding in size, shape and position to said protuberance.        
 
         [0052]     In an embodiment, two depressions are formed by a single machining operation, said depressions being formed on either side of said retaining groove and being adapted to receive corresponding protuberances provided on said rotary seal member.  
         [0053]     In another embodiment, one depression is formed by a single machining operation on one side of said retaining groove, each said depression being adapted to receive a corresponding protuberance provided on said rotary seal member.  
         [0054]     In a fifth aspect of the invention, there is provided a method of forming a rotary seal assembly for a hydraulic rotary swivel, said hydraulic rotary swivel including a first part and a second part rotatable relative to each other and having a common interface, said method comprising: 
        (i) forming a retaining groove in one of said first part and said second part at said interface, said retaining groove being adapted to receive a corresponding rotary seal member therein and to position said rotary seal member at said interface in between said first part and said second part to provide a seal;     (ii) forming in said retaining groove at least one depression corresponding to at least one protuberance provided on said rotary seal member;     (iii) fitting said corresponding rotary seal member in said retaining groove such that said at least one depression and said at least one protuberance are coupled,     such that, during operation of said rotary swivel, the interaction of said at least one protuberance and said corresponding depression assists in retaining said rotary seal member in a substantially stationary position relative to said retaining groove.        
 
         [0059]     In an embodiment, the method further comprises: 
        (iv) placing an energizing member in said retaining groove beneath said rotary seal member, such that said retaining groove urges said rotary seal member against an opposing sealing surface formed by the other of said first part and said second part.        
 
         [0061]     These foregoing and other aspects of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0062]     In the figures which illustrate various exemplary embodiments of the invention:  
         [0063]      FIG. 1A  shows a front view of an illustrative hydraulic rotary manifold in which exemplary embodiments of the invention may be found.  
         [0064]      FIG. 1B  is a top view of the hydraulic rotary manifold of  FIG. 1A .  
         [0065]      FIG. 1C  is a cross-section of the hydraulic rotary manifold of  FIG. 1B , showing a housing and a cylinder inside the housing.  
         [0066]      FIG. 2  is a perspective view of a rotary seal member in accordance with an exemplary embodiment, together with a cooperating energizer member (e.g. a resiliently deformable o-ring) and a corresponding retaining groove formed in an inner surface of the housing of  FIG. 1C .  
         [0067]      FIG. 3  is a linear “top view” representation of the retaining groove of  FIG. 2 .  
         [0068]      FIGS. 4A and 4B  are first and second cross-sections, respectively, taken through the retaining groove of  FIG. 3 .  
         [0069]      FIG. 5  is a linear “top view” representation of a rotary seal member in accordance with an exemplary embodiment.  
         [0070]      FIGS. 6A and 6B  are first and second cross-sections taken through the rotary seal member of  FIG. 5 , and shown together with a cross-section of the energizer member of  FIG. 2 .  
         [0071]      FIG. 7  is a linear “top view” representation of the rotary seal member of  FIG. 5  fitted into the retaining groove of  FIG. 3 .  
         [0072]      FIGS. 8A and 8B  are first and second cross-sections taken through  FIG. 7 , showing the seal and energizer member of  FIGS. 6A and 6B  in the groove of  FIG. 3 .  
         [0073]      FIG. 9A  is a detailed cross-section of a rotary seal member in accordance with an exemplary embodiment.  
         [0074]      FIG. 9B  is another view of the detailed-cross section of  FIG. 9A  showing the rotary seal member in use, and being acted on by various forces.  
         [0075]      FIG. 10  is a rotary seal member in accordance with another exemplary embodiment, together with an energizing o-ring, and a corresponding groove formed in an outer surface of a cylinder.  
         [0076]      FIG. 11A  is an illustrative example of a method of forming the depressions of  FIG. 3 .  
         [0077]      FIG. 11B  is an illustrative example of another method of forming the depressions.  
         [0078]      FIG. 12  is a rotary seal member and assembly in accordance with another exemplary embodiment. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0079]     Referring to  FIGS. 1A-1C , an illustrative hydraulic rotary swivel  100  is shown in which exemplary embodiments of the invention may be found.  FIG. 1A  is a “front view” of the hydraulic rotary swivel  100 ,  FIG. 1B  is a corresponding “top view”, and  FIG. 1C  is a cross-section taken through the hydraulic rotary swivel  100  of  FIG. 1A  at  1 C- 1 C. Typically, the hydraulic rotary swivel  100  of  FIGS. 1A-1C  may be machined from a block of metal, such as steel or ductile iron. Various other metals may also be used. The hydraulic rotary swivel  100  of  FIGS. 1A-1C  is merely illustrative, and is not meant to be limiting in terms of the type of rotary equipment in which the invention can be used.  
         [0080]     The hydraulic rotary swivel  100  of  FIGS. 1A-1C  may also be called a “hydraulic rotary manifold” or “hydraulic rotary union”. A “manifold” is a block having chambers or channels branching through it from/to a plurality of openings in the block. For the purposes of the present description, the terms “swivel”, “manifold”, and “union” may be used interchangeably and will all have the same meaning.  
         [0081]     As shown in  FIGS. 1A-1C , the hydraulic rotary swivel  100  includes a first part and a second part rotatable relative to each other and held in fixed longitudinal relation to each other. In this illustrative example, a “barrel” or outer housing  110 , and a “spool” or inner cylinder  120  provided inside the outer housing  110  comprise the first and second parts which can swivel or rotate relative to each other about a common, central, longitudinal axis Y-Y ( FIGS. 1A and 1C ) in one or both directions. The rotational mount of each part can be continuous or intermittent in one direction, or alternate in direction. It will be appreciated, and in this specification and claims, it is to be understood, that being rotatable relative to each other means, either or both of the first and second parts might be capable of rotation relative to a reference frame. Typically, however, in a piece of commercial equipment, one part will usually be held stationary relative to a supporting frame and the other member will rotate relative to that one part and the supporting frame. In this invention, it does not matter which part(s) actually rotates relative to a frame of reference. In the preferred embodiments discussed herein, one or both of the first and second parts both rotate about a common, central, longitudinal axis. The rotation of the first and/or second parts is typically caused by a separate conventional drive device or mechanism (not shown), the nature of which will depend upon the particular application in which the rotary swivel is employed.  
         [0082]     A plurality of channels  130   a - 130   c  and corresponding openings  140   a - 140   e  may be formed in the inner cylinder  120  and the outer housing  110  to provide fluid communication of a pressurized hydraulic fluid such as a pressurized hydraulic oil through a plurality of channels between and through the outer housing  110  and inner cylinder  120 , even as the outer housing  110  and cylinder rotate relative to each other. (For the sake of brevity, only some of the channels and openings are labeled in  FIGS. 1A-1C .) The hydraulic pressure of the hydraulic fluid throughout the channels in the rotary swivel can vary considerably (e.g. 50-5000+ psi), and can vary in such a manner even at the same location.  
         [0083]      FIG. 1C  shows a plurality of rotary seal assemblies  200  (as shown in detail in  FIG. 2  below) located between the outer housing  110  and the inner cylinder  120 . The rotary seal assemblies  200  may form annular “compartments” or “stages” in spaces formed between the outer housing  110  and the inner cylinder  120 . For example, channel  130   a  leads to secondary channel  132   a  which is in fluid communication with one such compartment  150   a . As shown, opening  140   d  is also in fluid communication with the compartment  150   a  via another secondary channel  132   b . Furthermore, channel  130   c  leads to secondary channel  132   c  which is in fluid communication with a compartment  150   b . As will be appreciated by those skilled in the art, various arrangements and configurations for such channels  130   a - 130   c ,  132   a - 132   c , openings  140   a - 140   e , and compartments  150   a - 150   b  are possible. Additional details on a possible configuration of the compartment  150   a , the channels  132   a ,  132   b , and adjacent rotary seal assemblies  200  are provided further below with reference to  FIGS. 9A and 9B .  
         [0084]      FIG. 2  shows a perspective view of a rotary seal assembly  200  in accordance with an exemplary embodiment. The rotary seal assembly  200  includes a suitably sized rotary seal member  210 , a suitably sized and shaped energizer member  220 , and a corresponding retaining groove  230  formed in a surface. For example, as shown, the retaining groove  230  may be formed in an inner surface  111  of the outer housing  110  of  FIG. 1 . (For illustration, only a small longitudinal section  10 ′ of the outer housing  110  is shown in a cut-out view in  FIG. 2 .) The seal member  210  is suitably sized so as to be able to be received in retaining groove  230  along with energizer member  220 , and to function as a seal.  
         [0085]     As known to those skilled in the art, the energizer member  220  is used to “energize” the seal member  210  so that a secure seal is obtained between the seal member  210  and an opposing sealing surface. For example, the energizer member  220  may be a resiliently deformable o-ring which can be suitably shaped and sized to be friction and/or compression fitted on the rotary seal member  210 . The resiliently deformable o-ring may then provide a compression fit seal between the rotary seal member  210  and the corresponding retaining groove  230 .  
         [0086]     The o-ring may be made of a suitable rubber or polymer compound. The inventors have discovered that nitrile is a particularly effective material for the energizer member  220  or o-ring, as nitrile exhibits desirable properties including resilience, durability, and resistance to breakdown by hydraulic fluids and lubricants.  
         [0087]     When subjected to hydraulic fluids as described hereafter (with reference to  FIGS. 9A and 9B , below), in addition to applying resilient compression energizing forces on the seal member  210 , the energizer member  210  may exert a further energizing force to further urge the rotary seal member  210  against an opposing sealing surface of inner cylinder  120 . This is explained in more detail with reference to  FIGS. 9A and 9B  below.  
         [0088]     The rotary seal member  210  may have an elongate body forming a ring, with an outer surface, an inner surface and two sides. The rotary seal member  210  may also have a slight recess  211  on its outer surface to receive the energizer member  220 . The rotary seal member  210  may also have a sealing surface adapted to sealingly contact an opposing sealing surface on the inner cylinder  120 , while permitting the sealing surface of said rotary seal member  210  to rotate relative thereto.  
         [0089]     The rotary seal member  210  has at least one protuberance  212   a - 212   f ,  213   a - 213   f  (collectively  212 ,  213 ) formed thereon. (Protuberances  213   a - 213   c  are hidden from view in  FIG. 2 .) As shown, in an embodiment, the protuberances  212   a - 212   f ,  213   a - 213   f  may extend laterally from the sides of the rotary seal member  210 .  
         [0090]     While six sets of evenly spaced protuberances  212   a - 212   f ,  213   a - 213   f  are shown, in alternative embodiments, other than six sets, and other than even spacing between the protuberances may be used. Also, while the protuberances  212   a - 212   f ,  213   a - 213   f  are shown to be evenly sized, in alternative embodiments, other than evenly sized protuberances may also be used. As well, while the protuberances  212   a - 212   f ,  213   a - 213   f  are shown extending from both sides of the rotary seal member  210 , it will be appreciated that, in an alternative embodiment, the protuberances need extend from only one side. Furthermore, while the protuberances  212   a - 212   f ,  213   a - 213   f  are shown as having a shape that is a part of a circle, it will be appreciated that in alternative embodiments, rectangular, triangular, or any other suitable shape (not shown) may also be used.  
         [0091]     The rotary seal member  210  may be made of a suitable plastic material having adequate hardness and durability for a given application. For example, the rotary seal member  210  may be made of Teflon™ (registered trademark of E. I. du Pont de Nemours and Company), filled Teflon, or acetal.  
         [0092]     As shown in  FIG. 2 , the retaining groove  230  may be provided with depressions  232   a - 232   f ,  233   a - 233   f  corresponding in size, position and spacing to each of the protuberances  212   a - 212   f ,  213   a - 213   f . (Depressions  232   a - 232   c ,  233   a - 233   c  are hidden from view in  FIG. 2 .) If the protuberances  212   a - 212   f ,  213   a - 213   f  are evenly spaced and evenly sized, it will be appreciated that the depressions  232   a - 232   f ,  233   a - 233   f  may be adapted to accommodate any one of the protuberances  212   a - 212   f ,  213   a - 213   f . However, as explained above, this need not be the case.  
         [0093]     The retaining groove  230  and the depressions  232   a - 232   f ,  233   a - 233   f  may be machined or formed from the material used to form the hydraulic rotary swivel  100 .  
         [0094]      FIG. 3  shows a more detailed schematic linear representation of the retaining groove  230  of  FIG. 2  in accordance with an exemplary embodiment. As described above, the retaining groove  230  may be formed, for example, on the inner surface  111  of the outer housing  110 . (Alternatively, a retaining groove  230 ′ may also be formed on an outer surface  211  of the inner cylinder  210 , as best shown in  FIG. 10  below.) For the purposes of illustration, only some of the depressions (namely depressions  232   a - 232   d ,  233   a - 233   d ) are shown in  FIG. 3 .  
         [0095]      FIGS. 4A and 4B  are first and second cross-sections, respectively, taken through the retaining groove  230  of  FIG. 3 . In an embodiment, as shown in  FIG. 4A , the depressions  232   a  and  233   b  are formed for only a part of the depth of the groove  230 .  FIG. 4B  shows a cross-section taken through the groove  230  at a location having no depressions.  
         [0096]      FIG. 5  is a linear representation of the rotary seal member  210  of  FIG. 2  in accordance with an exemplary embodiment. For the purposes of illustration, only some of the protuberances (namely protuberances  212   a - 212   d ,  213   a - 213   d ) are shown in  FIG. 3 . As shown, the depressions  232   a - 232   d ,  233   a - 233   d  of  FIG. 3  correspond closely in size, position and spacing to the protuberances  212   a - 212   d ,  213   a - 213   d.    
         [0097]      FIGS. 6A and 6B  are first and second cross-section views, respectively, taken through the rotary seal member  210  of  FIG. 5 , and shown together with an energizer member  210 .  FIG. 6A  is a cross-section view taken at protuberances  212   a  and  213   a , and  FIG. 6B  is a cross-section view taken at a location having no protuberances. As shown in  FIG. 6A , the protuberances  212   a ,  213   a  are suitably shaped and sized to fit in the depressions  232   a ,  233   a  shown in  FIG. 4A .  
         [0098]     Also, as shown in  FIG. 6A , the protuberances  212   a ,  213   a  have a thickness less than the thickness of the rotary seal member  210 . This is so that, if the rotary seal member  210  is urged by hydraulic pressure against one of the side walls  232   a ,  232   b  of the groove  232  (as explained with reference to  FIG. 9B  below), then the rotary seal member  210  will be able to form a continuous sealing surface against one of the walls  230   a ,  230   b.    
         [0099]     As shown in  FIGS. 6A and 6B , the surface of the rotary seal member  210  may be provided with a plurality of raised seal contact points  215 , which are explained in more detail with reference to  FIG. 9B , below.  
         [0100]      FIG. 7  is a linear representation of the rotary seal member  210  of  FIG. 5  fitted into the corresponding retaining groove  230  of  FIG. 3 . As shown, all of the protuberances  212   a - 212   d ,  213   a - 213   d  and the corresponding depressions  232   a - 232   d ,  233   a - 233   d  are matched, so that the rotary seal member  210  is prevented from rotating in the groove  230 .  
         [0101]     It will be noted that in this embodiment, the rotation of seal member  210  is prevented in both rotational directions (i.e. it will be prevented no matter which direction the outer housing and/or inner housing are rotating). However, the protuberances and corresponding depressions may be configured so as to prevent rotation of the seal member in the groove in only one direction, if that is all that is required.  
         [0102]     Also, it should be noted that a a precise matching or mating of protuberances and depressions may not be necessary to achieve the desired effect of preventing rotation of the seal member  210  in the retaining groove  230 .  
         [0103]      FIGS. 8A and 8B  show a cross-section of the retaining groove  230 , the energizer member  220 , and the rotary seal member  210 , as well as an opposing sealing surface (provided here, for example, by the outer surface of the inner cylinder  120 ). As will be appreciated, the rotary seal member  210  must protrude at least slightly out of the retaining groove  230 . As the rotary seal member  210  is energized by the energizer member  220  (as described further hereafter), it is the rotary seal member  210  and not the inner surface  112  of the outer housing  110  which contacts the outer surface of the inner cylinder  120 .  
         [0104]      FIG. 9A  is a detailed cross-section of a pair of rotary seal assemblies (such as those shown in cross-section in  FIGS. 8A and 8B ) forming a sealed compartment or cavity therebetween. More specifically, compartment  150 A ( FIG. 1C ) connected by a pair of channels  132 A,  132 B ( FIG. 1C ) is sealed on either side by a rotary seal assembly, each including a rotary seal member  210 , an energizer member  220 , and a retaining groove  230 . As shown, a gap  902  is formed between the outer housing  110  ( FIG. 1C ) and the inner cylinder  120  ( FIG. 1C ). In an embodiment, the rotary seal member  210  and energizer member  220  may be suitably shaped and sized to have some degree of lateral clearance, leaving a space  904  with one of the side walls of the retaining groove  230 .  
         [0105]     In  FIG. 9A , the rotary seal assembly on the right has a cross-section through protuberances  212 A,  213 A and corresponding depressions  232 A,  233 A, as previously shown in  FIG. 8A . The rotary seal assembly on the left has a cross-section as previously shown in  FIG. 8B .  
         [0106]      FIG. 9B  shows the same view as in  FIG. 9A  but with the compartment  150 A, channels  132 A,  132 B, gaps  902  (between the rotary seal assemblies), and gaps  904  filled with a hydraulic fluid. As shown, during operation of the hydraulic rotary swivel  100 , the pressurized hydraulic fluid flowing thorough the passageways in the swivel between the outer housing  110  and the inner cylinder  120  exerts hydraulic pressure “H” on the rotary seal members  210  and the energizer members  220  to urge them against an opposite side wall of the retaining grooves  230 .  
         [0107]     In normal operation, the energizer members  220  are designed to urge the rotary seal members  210  up against opposing sealing surfaces (in this example, the outer surface of the inner cylinder  120 ). As shown, each of the energizer members  220  exerts an energizing force “E” on the seal member  210  as a result of various mechanical forces and hydraulic pressure acting on the energizer members  220 . More specifically, as previously discussed, the energizing force “E” may include a resilient force component (i.e. the resilient force exerted by the energizer member  220  upon compression), as well as an additional force resulting from application of hydraulic pressure on the energizer member  220 . As will be apparent from  FIG. 9B , the hydraulic pressure “H” will have a tendency to deform the energizer members  220  such that the energizer members  220  further urge the seal members  210  against the opposing sealing surface provided by the outer surface of the inner cylinder  120 .  
         [0108]     As described earlier, raised seal contact areas  215  may be used to reduce the overall frictional forces between the rotary seal member  210  and an opposing sealing surface. As well, spaces between the raised seal contact areas  215  may retain hydraulic fluid that may reduce friction.  
         [0109]     Over time, however, various factors may cause frictional forces between the rotary seal member  210  and an energizer member  220  to become less than is necessary to overcome the dynamic frictional forces created during relative rotation between the rotary seal member  210  and an opposing sealing surface in housing  120 . Again, it will be appreciated that it is only important that there is relative rotational movement between the seal member  210  held on inner cylinder  110  and outer housing  120 . With previous rotary seal assembly designs, this has often lead to the problem identified earlier, where a rotary seal member may undesirably rotate against a part (e.g. the energizer  220 ) not designed to sustain significant dynamic friction.  
         [0110]     Advantageously, due to at least one protrusion  212 A,  213 A being provided on the rotary seal member  210 , and a corresponding depression  232 A,  233 A being provided along the retaining groove  230 , the rotary seal member  210  can be substantially prevented from rotating in the retaining groove in the same direction as frictional force “F”, due to counteracting resistance forces “R” provided by the interaction between the at least one protrusion  212 A,  213 A and the corresponding depression  232 A,  233 A (see  FIG. 7 ). As will be appreciated, this may significantly extend the life of an energizer member  220  used with the rotary seal member  210 , and consequently the seal formed by a rotary seal assembly may last longer. This may in turn extend the operational life of a hydraulic rotary swivel  100  using such a rotary seal assembly.  
         [0111]     In an alternative embodiment, as shown in  FIG. 10 , a rotary seal member  210 ′ may be adapted to be placed in a corresponding groove  230 ′ formed in an outer surface  121  of the inner cylinder  120 . In this embodiment, the rotary seal member  210 ′ may have suitable resilience characteristics allowing the rotary seal member  210 ′ to be stretched slightly to be fit into place in the corresponding groove  230 ′. Here, for illustration, a small section  120 ′ of the inner cylinder  120  is shown. As well, for illustration, a channel  130   b  ( FIG. 1C ) is shown passing through the inner cylinder  120 .  
         [0112]     In the embodiment shown in  FIG. 10 , a plurality of protuberances  212   a ′- 212   f ′,  231   a - 213   f ′ (protuberances  213   d ′- 213   f ′ are hidden in  FIG. 10 ) extend laterally adjacent an outer edge of the rotary seal member  210 ′ (as compared to the inner edge of rotary seal member  210  as shown in  FIG. 2 ). As shown, corresponding depressions  232   a ′- 232   f ′,  233   a ′- 233   f ′ (corresponding depressions  232   d ′- 232   f ,  233   d ′- 233   f ′ are hidden in  FIG. 10 ) are provided along the retaining groove  230 ′. A corresponding energizer member  220 ′ (e.g. a resiliently deformable o-ring) may be suitably sized and shaped to be placed in the groove  230 ′ and to urge the rotary seal member  210 ′ against an opposing sealing surface (such as the inner surface of the outer housing  110 ). During the relative rotational movement of the inner cylinder  120  and outer housing  120 , the seal is prevented from rotating relative to the outer housing  110  and its corresponding groove.  
         [0113]      FIG. 11A  is an illustrative example of a method of forming depressions  232   a ,  233   a  in the groove  230  of  FIG. 3 . In an embodiment, a cutting tool (not shown) of a suitable diameter may be used to machine both depressions  232   a ,  233   a , having a width “W”, at the same time. Also, as shown, a tangential angle “A” is formed by the depression  232   a . It will be understood that the depth of the depressions  232   a ,  233   a  may be controlled by the depth of penetration of the cutting tool.  
         [0114]      FIG. 11B  is an illustrative example of another method of forming alternative depressions  232   a ″,  233   c ″ in the groove  230  of  FIG. 3 . In this embodiment, a smaller cutting tool of a suitable diameter (not shown) may be used to form the depressions  232   a ″,  233   c ″, having a width “W”, in two operations. As shown, using this alternative method, a sharper tangential angle “B” may be formed by the depression  232   a ″. With correspondingly shaped protuberances  212   a ″,  213   a ″ formed on a rotary seal member  210 ″, it will be appreciated that the sharper angle B may provide a more secure catch to prevent the rotary seal member  210 ″ from rotating. This may be particularly significant if a gap is provided between the rotary seal member  210 ″ and the corresponding retaining groove  230  such that there is some “play” between the rotary seal member  210 ″ and the retaining groove  230 .  
         [0115]     While exemplary embodiments of the invention have been described, it will be apparent to those skilled in the art that various changes and modifications may be made. For example, while the rotary seal member  220 ,  220 ′,  220 ″ described above has been shown placed in a groove formed either on an outer surface of an inner cylinder  120 , or on an inner surface of an outer housing  110 , more generally, it will be appreciated that a rotary seal member may be provided at virtually any interface formed between a first part and a second part rotatable relative to each other and where a seal is required.  
         [0116]     For example, as shown in  FIG. 12 , a modified rotary seal member  220 E may be received in a retaining groove  230 E formed into an end surface of a first cylinder  120 E. A second cylinder  120 F positioned above cylinder  120 E provides an opposing sealing surface and may rotate relative to the first cylinder  120 E. Based on the embodiments already described, with reference to  FIG. 2 - FIG. 11B , it will be readily apparent to those skilled in the art that various channels, inlets and outlets may be formed between and through the first and second cylinders  120 E and  120 F to provide various arrangements for sealing fluids, such as hydraulic fluids, while one cylinder rotates relative to the other.  
         [0117]     As shown, a plurality of protuberances  212 AE,  213 AE,  212 BE,  213 BE provided on the rotary seal member  220 E may be fitted into corresponding depressions  232 AE,  233 AE,  232 BE,  233 BE provided along the retaining groove  230 E to prevent the rotary seal member  220 E from rotating within the retaining groove  230 E. Other protuberances and corresponding depressions are hidden from view in  FIG. 12 . Taking into account the different orientation, it will be appreciated that the identified seal failure problem and the solution to the problem as taught by the present invention are also applicable to the illustrative example shown in  FIG. 12 .  
         [0118]     It will be appreciated that numerous other variations and embodiments are possible, the scope of the invention being limited only by the following claims.