Abstract:
Seal assemblies for sealing around a moveable shaft, such as rotary or reciprocating, or static, are described. The seal assemblies prevent the passage of lubricant or fluid from a relatively high pressure area on a first side of the seal to a relatively low pressure area on a second side of the seal. In some embodiments, these seals are energized by energizers, such as circular springs or canted springs, to keep the seal in contact with the moveable shaft. The seals have primary and secondary seals. The secondary seal provides initial moderate sealing against abrasive particles or contaminants to reduce the exposure and wear of the primary seal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This is a regular utility application of provisional application Ser. No. 61/162,431 filed Mar. 23, 2009, the contents of which are expressly incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to shaft seals for use in rotary, reciprocating, and static applications. 
         [0004]    2. Description of Related Art 
         [0005]    Shaft seals generally include a seal that extends around a shaft and prevents the passage of lubricant from a relatively high pressure area on a first side of the seal to a relatively low pressure area on a second side of the seal. In some embodiments, these seals are energized by circular springs to provide energized force to the seal to keep the seal in contact with the rotating or reciprocating shaft. 
       SUMMARY 
       [0006]    The various embodiments of the present seal assemblies for rotary, reciprocating, and/or static shafts have several features, no single one of which is solely responsible for their desirable attributes. Embodiments of the present seal assemblies for rotary, reciprocating, and/or static shafts include redundant or dual seals and may include various locking rings. Without limiting the scope of the present embodiments as expressed by the claims that follow, their more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled Detailed Description, one will understand how the features of the present embodiments provide advantages, which include increased sturdiness, resistance to rotation, resistance to axial movement, and extrusion resistance, among others. The secondary seal provides initial moderate sealing against abrasive particles or contaminants to reduce the exposure and wear of the primary seal. The present embodiments achieve enhanced performance, reliability, and improved seal life, among others. 
         [0007]    One aspect of the present seal assemblies includes the realization that with conventional rotary, liplike, energized seals, the single energized sealing lip or single sealing component may not be enough to provide complete sealing in some applications. In the event that the seal leaks or fails, a secondary seal would be very beneficial to the sealing component to provide backup or redundant sealing ability on a temporary basis. A feature of the present assembly is the structure and arrangement of components to enable incorporation of a secondary seal into a small and often confined space. 
         [0008]    One embodiment of the present seal assembly is configured for sealing around a movable or static shaft. The seal assembly comprises a primary seal engaging the shaft at a first location. The seal assembly further comprises a secondary seal engaging the shaft at a second location spaced apart from the first location. The seal assembly further comprises a locking ring for retaining the primary and secondary seals with respect to the shaft. The primary seal is constructed of a first material and the secondary seal is constructed of a second material. The second material has a higher modulus of elasticity than the first material. 
         [0009]    Another embodiment of the present seal assembly is configured for sealing around a movable or static shaft. The seal assembly comprises a primary seal engaging the shaft at a first location. The seal assembly further comprises a secondary seal engaging the shaft at a second location spaced apart from the first location. The seal assembly further comprises a locking ring for retaining the primary and secondary seals with respect to the shaft. The locking ring and the secondary seal comprise a unitary component. 
         [0010]    Another embodiment of the present seal assembly is configured for sealing around a movable or static shaft. The seal assembly comprises a primary seal engaging the shaft at a first location. The seal assembly further comprises a locking ring for retaining the primary seal with respect to the shaft. A portion of the locking ring comprises a secondary seal engaging the shaft at a second location spaced apart from the first location. 
         [0011]    Another embodiment of the present seal assembly is configured for sealing around a movable or static shaft. The seal assembly comprises a primary seal engaging the shaft at a first location. The seal assembly further comprises a secondary seal engaging the shaft at a second location spaced apart from the first location. The seal assembly further comprises a housing containing the primary and secondary seals. The seal assembly further comprises a locking ring for retaining the primary and secondary seals with respect to the housing and the shaft. The locking ring includes a circumferential groove that reduces a contact area between the locking ring and the housing. 
         [0012]    Another embodiment of the present seal assembly is configured for sealing around a movable or static shaft. The seal assembly comprises a primary seal engaging the shaft at a first location. A secondary seal engaging the shaft at a second location spaced apart from the first location. Wherein one of the primary seal and the secondary seal is constructed of a first material and the other of the primary seal and the secondary seal is constructed of a second material, and the second material has a higher modulus of elasticity than the first material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The various embodiments of the present seal assemblies now will be discussed in detail with an emphasis on highlighting the advantageous features. These embodiments depict the novel and non-obvious seal assemblies shown in the accompanying drawings, which are for illustrative purposes only. These drawings include the following figures, in which like numerals indicate like parts: 
           [0014]      FIG. 1  is a front cross-sectional view of one embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0015]      FIG. 2  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0016]      FIG. 3  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0017]      FIG. 4  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0018]      FIG. 5  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0019]      FIG. 6  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0020]      FIG. 7  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0021]      FIG. 7A  is a detail view of the rotary, reciprocating, and/or static shaft redundant seal with locking means of  FIG. 7  showing an alternative configuration of the secondary seal; 
           [0022]      FIG. 7B  is a detail view of the rotary, reciprocating, and/or static shaft redundant seal with locking means of  FIG. 7  showing an alternative configuration of the secondary seal; 
           [0023]      FIG. 8  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0024]      FIG. 8A  is a detail view of the rotary, reciprocating, and/or static shaft redundant seal with locking means of  FIG. 8  showing an alternative configuration of the secondary seal; 
           [0025]      FIG. 8B  is a detail view of the rotary, reciprocating, and/or static shaft redundant seal with locking means of  FIG. 8  showing an alternative configuration of the secondary seal; 
           [0026]      FIG. 9  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0027]      FIG. 9A  is a detail view of the rotary, reciprocating, and/or static shaft redundant seal with locking means of  FIG. 9  showing an alternative configuration of the secondary seal; 
           [0028]      FIG. 10  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0029]      FIG. 10A  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0030]      FIG. 11  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0031]      FIG. 11A  is a detail view of the circled portion of the rotary, reciprocating, and/or static shaft redundant seal with locking means of  FIG. 11 ; 
           [0032]      FIG. 11B  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; 
           [0033]      FIG. 11C  is a detail view of the circled portion of the rotary, reciprocating, and/or static shaft redundant seal with locking means of  FIG. 11B ; 
           [0034]      FIG. 11D  is a front cross-sectional view of another embodiment of the present rotary, reciprocating, and/or static shaft redundant seal with locking means; and 
           [0035]      FIG. 11E  is a detail view of the circled portion of the rotary, reciprocating, and/or static shaft redundant seal with locking means of  FIG. 11D . 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    The following detailed description describes the present embodiments with reference to the drawings. In the drawings, reference numbers label elements of the present embodiments. These reference numbers are reproduced below in connection with the discussion of the corresponding drawing features. 
         [0037]    The embodiments illustrated herein describe spring-energized seals. The springs used in the present embodiments may comprise canted-coil springs. Other energizers, including O-rings, “V” springs, finger springs, etc., can be used in place of or in conjunction with the canted coil spring. In certain embodiments, the coil springs may be radially canted, while in certain other embodiments the coil springs may be axially canted. In still further embodiments, the coil springs may be both radially canted and axially canted. Canted-coil springs are described in detail in U.S. Pat. Nos. 4,655,462; 4,826,144; 4,876,781; 4,907,788; 4,915,366; 4,964,204; 5,139,243; 5,160,122; 5,503,375; 5,615,870; 5,709,371; 5,791,638; and 7,055,812. The contents of each of the foregoing patents are hereby expressly incorporated herein by reference. 
         [0038]      FIG. 1  shows one embodiment of the present rotary, reciprocating, and/or static shaft redundant seal assembly with locking means. Redundant, in this case, indicates that the two seals are incorporated into a single unit, as opposed to two sealing grooves forming part of an assembly whereby various seals are included. Redundant seal  1  comprises primary seal  2  energized by a spring  4  and a secondary seal  3  energized by a spring  5 , both providing sealing against shaft  7 . The redundant seal  1  comprises a cavity in which spring  4  and locking ring  6  is retained. The locking ring  6  retains and resists rotation or axial movement of the redundant seal  1  and thus the entire sealing assembly in retained in the housing  8  by creating interference between the locking ring  6  and the housing  8 . 
         [0039]    In one example, a seal body  1 . 1  is provided comprising two spaced apart seal lips  1 . 2 ,  1 . 3 . As shown, the primary seal lip  1 . 2  is larger than the secondary seal lip  1 . 3 , both in length, thickness, and cavity for receiving a respective energizer. The seal body may be made from an elastomer material or a thermoplastic elastomer (TPE) material of the type selected for the operating conditions. In addition, as shown, the locking ring  6  engages the seal body and forms parts of the cavity  1 . 4  for retaining the primary loading spring  4 . 
         [0040]      FIG. 2  shows an alternative embodiment of a redundant seal  1 . 5  similar to  FIG. 1 , except that the locking ring is omitted. A retaining lip  1 . 6  is formed with the seal body for retaining the loading spring  4 . The seal of  FIG. 2  is particularly advantageous for reciprocating shaft applications. 
         [0041]      FIG. 3  shows another embodiment in which a triangular or inverted-V scraper  10  is incorporated into the inside diameter of the seal  9 , which is energized by a spring  11 , to act as a backup scraper to the seal  9 . The seal  9  comprises a cavity in which the spring  11  and a locking ring  12  are retained. The locking ring  12  retains and resists rotation or axial movement of the seal assembly in housing  8  by creating interference between locking ring  12  and housing  8 . The scraper  10  may be considered as an additional seal, in this instance a secondary seal. 
         [0042]    Under conditions of elevated pressure and temperature, the scraper backup ring  10  resists the seal  9  extruding, thus increasing seal life. The reduction in area due to the triangular cross-section of the scraper  10  compared to, for example, a cavity with an energizer is preferred since the compactness of the scraper backup ring allows for greater retention of the triangular shape into the inside diameter of the seal  9 . In turn, the arrangement provides a greater degree of retention and limits the extrusion of the seal plastic at elevated temperatures. Thus, a feature of the present device, assembly and method includes a backup scraper  10  having a generally triangular shape, which in one embodiment is a V-shape. In one example, the backup scraper  10  is positioned further away from a high pressure source than the seal  9 . In another example, the backup scraper  10  is made from a harder material than the seal body  9 . 1 , such as from an engineered plastic or a metal, and resists seal extruding, such as by providing axial support for the seal along the direction of the shaft  7 . In still yet another embodiment, the backup scraper  10  comprises two spaced apart scraper edges  10 . 1 ,  10 . 2 , which are separated from one another by a space  10 . 3 , which in one example has a V-shaped contour. A still yet further feature of the present embodiment is a method of making the seal and method of using the seal. Exemplary engineered plastic includes polycarbonates (PC), polyamides (PA), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyphenylene oxide (PPO), polysulphone (PSU), polyetherketone (PEK), polyetheretherketone (PEEK), polyimides, and polyphenylene sulfide (PPS). 
         [0043]      FIG. 4  shows an alternative embodiment similar to  FIG. 3  that includes a different type of backup ring  13 . The backup ring  13  is similar in design to the one in  FIG. 3 , but is locked into the internal end portion of the seal  14 , which improves retention during use. The backup ring  13  is also located in the internal end portion of the seal  14  to resist extrusion of the seal material and as shown contacts the housing  8 . The backup ring  13  includes a circumferential tapered groove  13 A to reduce the contact area between the backup ring  13  and the shaft  7  to reduce heat generated by friction. In other words, the scraper surfaces or edges  13 . 1 ,  13 . 2  are made narrower lengthwise compared to if the groove  13 A was straight or not as tapered. A locking ring  15  resists the seal moving in a rotating or reciprocating manner. As shown, the backup ring  13  has a projection  13 . 3  that projects into the seal body  9 . 2  and contacts the housing  8 . In another example, the backup ring  13  contacts the seal body  9 . 2 , the housing  8 , and the shaft  7 , simultaneously. 
         [0044]      FIG. 5  shows an alternative embodiment similar to  FIG. 4  that is particularly advantageous for reciprocating applications. The embodiment of  FIG. 5  includes no locking ring, since under conditions of high pressure the seal  16  is usually forced toward the end of the cavity. There is thus less incentive to have a locking ring to resist axial movement. 
         [0045]      FIG. 6  shows an alternative embodiment that includes two seals. Primary seal  17  is energized by a spring  20  and secondary seal  18  is energized by a spring  21 . The two seals are incorporated into one assembly and are held together by an integrated locking ring  19 . The locking ring  19  may comprise a material, such as a plastic, that provides locking and sealing in combination with the secondary seal  18 . In one embodiment, the primary seal  17  offers superior sealing ability compared to the secondary seal  18 . For example, by incorporating certain material properties, such as an elastomer or a TPE, the seal lip is more pliable and seals against the shaft better than the secondary seal  18 , which may be made from a high modulus material and therefore has relatively lesser sealing ability. However, by using a high modulus material, the secondary seal provides moderate sealing of abrasive and/or contaminants to thereby reduce the exposure and wear of the primary seal  17 . The locking ring  19  retains the two seals in one assembly unit. In an alternative embodiment, the locking ring  19  may be omitted, leaving a primary seal and a secondary seal, with one or the other of the seals being made from a high modulus material. Thus, a feature of the present embodiment is a combination locking ring  19  that engages with a primary seal  17  and that has a sealing lip  18 . 1  and a cavity having an energizer  21  disposed therein for energizing the sealing lip  18 . 1  towards the shaft  7 . A further feature of the present seal assembly is a secondary seal  18  that is positioned closer to a high pressure source than the primary seal  17  to reduce abrasive and/or contaminants from reaching the primary seal. A still further feature of the present seal assembly is a locking ring  19  that engages a primary seal  17 , that has a sealing lip  18 . 1  to provide secondary sealing, and that forms part of a cavity  17 . 1  for retaining a primary energizer  17 . 2 . A still yet further feature of the present embodiment is a method of making the alternative seal and method of using the alternative seal. 
         [0046]      FIG. 7  shows an alternative embodiment similar to  FIG. 6  except that the secondary seal  24  has been replaced with a memory liplike seal  23  instead of a spring energized seal. In other words, the liplike seal has elastic properties that allow it to bias against the shaft  7  without an energizer.  FIG. 7A  shows another alternative embodiment in which a garter spring  26  is incorporated into the secondary seal  23  to provide radial force to increase sealing ability at the lip.  FIG. 7B  shows another alternative embodiment in which a toroidal O-ring  27  provides the radial sealing force. 
         [0047]      FIG. 8  shows an alternative embodiment of the present rotary, reciprocating, and/or static shaft seal assembly having a primary seal  28  energized by a spring  31  and a secondary seal  29 . The secondary seal  29  is part of the locking ring  30  and includes a toroidal O-ring or rectangular cross-section O-ring  29 . 1  located within a groove  29 . 2  to provide secondary sealing against the shaft  7 . The sealing ring is detachable from the groove  29 . 2 . As shown, the locking ring  30  comprises a flange  30 . 1  having the groove  29 . 2  formed at a radial end thereof. The locking ring  30 , and in particular the flange  30 . 1 , contacts the spring  31  and forms part of the cavity for retaining the spring  31 . The locking ring  30  provides a support that allows for the mounting of the secondary seal, thus providing sealing ability between the shaft  7  and the locking ring  30 .  FIG. 8A  shows an alternate embodiment including a circumferential seal  32  having a small contact area  32 . 1  with the shaft.  FIG. 8B  shows an alternate embodiment of the secondary seal in which an extension garter spring  33  provides additional energizing force to affect sealing. A still yet further feature of the present embodiment is a method of making the seal assembly and method of using the seal assembly. 
         [0048]      FIG. 9  shows an alternative embodiment comprising a dual in-line sealing system with locking ring  37  and primary seal  34  having an energizer  38 , such as a canted coil spring. The secondary seal  35  may be molded integrally with the locking ring  37  or separately molded and bonded or engaged to the locking ring. The seal lip  35 . 1  of the secondary seal may be made from a high modulus material to reduce abrasive and/or contaminants from reaching the primary seal or may be made from a softer material, such as an elastomer or a TPE, that engages the locking ring.  FIG. 9A  shows an alternative embodiment of the secondary seal  37  in which the secondary seal  39  is energized with a canted-coil spring  39 A. 
         [0049]      FIG. 10  shows an alternative embodiment comprising a redundant rotary, reciprocating, and/or static shaft seal assembly with a locking ring  44 . The secondary seal  41  is located rearward from the primary seal  40  and functions primarily as a dust seal. The secondary seal  41  is energized with a canted-coil spring  43 . The locking ring  44  retains the seal in the housing  45 . The seal body  40 . 1  thus comprises both the primary sealing lip  10 . 2  and secondary sealing lip  41 . 1 . Thus, a feature of the present seal assembly is a double seal comprising a singularly formed seal body that is energized by two energizers. A still further feature is a singularly formed seal body that has two sealing lips and two energizers and wherein the energizers energize the two sealing lips.  FIG. 10A  shows an alternative embodiment similar to  FIG. 10  in which no locking ring is provided to retain the seal in position. Instead, a support ring  47  retained the seal in the housing  46 . Also shown are primary sealing lip  40 . 5  and secondary sealing lip  40 . 6 . 
         [0050]      FIG. 11  shows an alternative embodiment in which a single locking ring  50  retains two separate seals, primary seal  48  and secondary seal  49 , thus providing a rotary, reciprocating, and/or static shaft dual seal spring energized by springs  51  and  52 . The single locking ring  50  may be retained in the housing  8  by pressing the locking ring into the housing with an interference between the outside diameter of the locking ring and the inside diameter of the housing  8 .  FIG. 11A  shows a detail view of the circled section of  FIG. 11 , outlining the manner in which the locking or engagement is achieved between the interference of the locking ring outside diameter and the housing inside diameter. As shown, the locking ring  50  has a plus “+” shape cross-section comprising a vertical arm  50 . 1  and a crossing horizontal arm  50 . 2 . In one example, both the primary seal body  48 . 1  and the secondary seal body  49 . 1  are made from a pliable material, such as an appropriate elastomer or TPE material. In another example, the secondary seal body  49 . 1  is made from a more rigid material than the primary seal body  48 . 1 , such as a high modulus material, for example engineered plastic or metal. 
         [0051]      FIG. 11B  shows an alternative embodiment similar to  FIG. 11  in which a variation of the locking ring  50 . 5  includes a circumferential groove  53  that reduces the area of contact at the interference between the outside diameter of the locking ring and the housing diameter.  FIG. 11C  shows a detail view of the circled section of  FIG. 11B , outlining the circumferential groove  53  and the manner in which the engagement is achieved between the interference of the locking ring outside diameter and the housing inside diameter. 
         [0052]      FIG. 11D  shows yet another alternative embodiment similar to  FIGS. 11 and 11B  in which an axial groove  54  includes a cantilever spring  55  that allows for variation in tolerances due to the deflection of the cantilever spring  55 , thus affording greater variation in tolerances and facilitating ease of manufacturing.  FIG. 11E  shows a detail view of the circled section of  FIG. 11D , outlining the manner in which the interference occurs between the outside diameter of the locking ring and the inside diameter of the housing. 
         [0053]    The present seal assemblies for rotary, reciprocating, and/or static shafts and static applications offers a series of double-sealing seal assemblies with multiple design features such as increased sturdiness, resistance to rotation, resistance to axial movement, and extrusion resistance. The present seal assemblies also offer increased seal life through using a secondary seal to provide initial moderate sealing against abrasive particles or contaminants to reduce the exposure and wear of the primary seal. The present assemblies also provide a back up seal that can provide moderate sealing if the primary seal happens to fail or leak, all resulting in enhanced performance and reliability. 
         [0054]    The above description presents the best mode contemplated for carrying out the present seal assemblies, and of the manner and process of making and using them, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains to make and use these seal assemblies. These seal assemblies are, however, susceptible to modifications and alternate constructions from that discussed above that are fully equivalent. Consequently, these seal assemblies are not limited to the particular embodiments disclosed. On the contrary, these seal assemblies cover all modifications and alternate constructions coming within the spirit and scope of the seal assemblies as generally expressed by the following claims, which particularly point out and distinctly claim the subject matter of the seal assemblies.