WO2015095551A1

WO2015095551A1 - Seal assembly with expandable sealing member

Info

Publication number: WO2015095551A1
Application number: PCT/US2014/071209
Authority: WO
Inventors: Yefim Epshetsky; John Manuel DOMINGUEZ
Original assignee: Aktiebolaget Skf
Priority date: 2013-12-20
Filing date: 2014-12-18
Publication date: 2015-06-25

Abstract

A seal assembly includes an annular sealing lip extending about a central axis and sealingly engageable with a shaft. An annular elastomeric base is disposed generally coaxially about and connected with the lip and has two opposing axial sides and an outer circumferential surface contactable with a housing inner circumferential surface. An expander device includes first and second clamp members, each disposed against a separate base inner portion axial side, and one or more couplers having an end coupled with a portion of the first clamp member and another end coupled with a portion of the second clamp member. Each coupler is configured to displace each connected clamp member portion generally axially toward the other clamp member portion to compress an inner portion of the base to displace an outer portion of the base generally radially outwardly such that the base outer surface sealingly engages the housing inner surface.

Description

TITLE OF THE INVENTION

Seal Assembly with Expandable Sealing Member

BACKGROUND OF THE INVENTION

The present invention relates to seals, and more particularly to radial lip seals.

Radial lip seals are known and typically include and an annular elastomeric sealing member with a cantilever-like sealing lip and an annular case for coupling the sealing member to a housing. In many seal products, the case is a metallic member to which the separate sealing member is bonded or otherwise attached. To install such a seal within a housing, the outer circumferential surface of the metallic case slides against an inner circumferential surface of the housing until reaching a desired axial position relative to the shaft and housing.

In other types of seals, the case is an integral portion of the sealing member, such that the sealing member and casing are a one-piece elastomeric component. With such seals, the case is typically formed as a relatively thick elastomeric ring portion that is capable of resisting fluid pressure while remaining at a fixed axial position relative to a shaft and housing. Due to the substantially higher friction coefficient of elastomer and steel (as opposed to steel on steel) and the relatively large required thickness, installation of the seal assembly into the housing bore is relatively difficult and more likely to abrade or otherwise damage the elastomer.

SUMMARY OF THE INVENTION

In one aspect, the present invention is a seal assembly for sealing an annular space between a shaft with an outer circumferential surface and a housing having an inner

circumferential surface. The seal assembly comprises a generally annular sealing lip extending circumferentially about a central axis and sealingly engageable with the shaft outer surface. A generally annular elastomeric base is disposed generally coaxially about and connected with the lip, the base having an outer circumferential surface contactable with the housing inner circumferential surface. Further, an expander device is configured to compress an inner portion of the base so as to displace an outer portion of the base generally radially outwardly such that the base outer surface sealingly engages the housing inner surface.

In another aspect, the present invention is again a seal assembly for sealing an annular space between a shaft with an outer circumferential surface and a housing having an inner circumferential surface. The seal assembly comprises a generally annular sealing lip extending circumferentially about a central axis and sealingly engageable with the shaft outer surface. A generally annular elastomeric base is disposed generally coaxially about and connected with the lip, the base having a two opposing axial sides and an outer circumferential surface contactable with the housing inner circumferential surface. Further, an expander device includes first and second clamp members each disposed generally against a separate one of the two base inner portion axial sides and at least one coupler having a first end coupled with a portion of the first clamp member and a second end coupled with a portion of the second clamp member. Each coupler is configured to displace each one of the connected clamp member portions generally axially toward the other one of the clamp member portions to compress an inner portion of the base so as to displace an outer portion of the base generally radially outwardly such that the base outer surface sealingly engages the housing inner surface.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, which are diagrammatic, embodiments that are presently preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

Fig. 1 is radial end view of a seal assembly in accordance with the present invention, shown installed within a housing and about a shaft;

Fig. 2 is a broken-away, axial cross-sectional view through line 2-2 of Fig. 1;

Fig. 3 is a broken-away, axial cross-sectional view through line 3-3 of Fig. 1

Fig. 4 is a perspective view of the seal assembly, shown uninstalled from a housing and in a non-expanded state;

Fig. 5 is a broken-away, axial cross-sectional view through line 5-5 of Fig. 4;

Fig. 6 is a broken-away, axial cross-sectional view through line 6-6 of Fig. 4;

Fig. 7 is a broken-away, axial cross-sectional view of the seal assembly, showing the base in a non-expanded state and clamp members at distal positions; Fig. 8 is a broken-away, axial cross-sectional view of the seal assembly, showing the base in an expanded state and the clamp members at proximal positions;

Fig. 9 is a perspective view of an expander device, shown separate from a remainder of the seal assembly;

Fig. 10 is a broken-away, axial cross-sectional view of a preferred annular elastomeric body providing the base and a lip of a seal;

Fig. 11 is a broken-away, axial cross-sectional view of an alternative construction of the expander device, showing the seal in a non-expanded state;

Fig. 12 is another broken-away, axial cross-sectional view of the alternative construction expander device, showing the seal in an expanded state;

Fig. 13 is a broken-away, axial cross-sectional view of the seal assembly and housing, showing the seal assembly during insertion into a bore of the housing; and

Fig. 14 is a broken-away, axial cross-sectional view of the seal assembly and housing, showing the seal assembly during expansion of the base into sealing engagement with the housing bore.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenience only and is not limiting. The words "inner", "inwardly" and "outer", "outwardly" refer to directions toward and away from, respectively, a designated central axis or a geometric center of an element being described, the particular meaning being readily apparent from the context of the description. Further, as used herein, the word "connected" is intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. The terminology includes the words specifically mentioned above, derivatives thereof, and words of similar import.

Referring now to the drawings in detail, wherein like numbers are used to indicate like elements throughout, there is shown in Figs. 1-14 a seal assembly 10 for sealing an annular space S (Figs. 2 and 3) between a shaft 1 and a housing 2, the shaft 1 having an outer circumferential surface la and the housing 2 having an inner circumferential surface 2a defining a bore 3. The seal assembly 10 basically comprises a generally annular sealing lip 12, a generally annular elastomeric base 14 and an expander device 16. The sealing lip 12 extends circumferentially about a central axis Ac and is sealingly engageable with the shaft outer surface la. The base 14 is disposed generally coaxially about and connected with the lip 12 and has two opposing axial sides 15 A, 15B and an outer circumferential surface 17 contactable with the housing inner circumferential surface 2a. Further, the expander device 16 is configured to compress an inner portion 14a of the base 14 so as to displace an outer portion 14b of the base 14 generally radially outwardly such that the base outer surface 17 sealingly engages with the housing inner surface 2a, thereby retaining the seal assembly 10 within the housing bore 3. Additionally, the expander device 16 is further configured to alternatively release compression on the base inner portion 14a to enable inward radial displacement of the base outer portion 14b when it is desired to remove the seal assembly 10 from the bore 3.

Preferably, the expander device 16 includes first and second clamp members 18, 20 and at least one movable coupler 22 extending between the two clamp members 18, 20. The clamp members 18, 20 are each disposed generally against a separate one of the two base axial sides 15 A, 15B, respectively, and preferably within a separate groove 24, 26 formed in the base sides 15 A, 15B as described below. The at least one coupler 22 has a first end 22a coupled with a portion 18a of the first clamp member 18 and a second end 22b coupled with a portion 20a of the second clamp member 20. Further, the coupler 22 is configured to displace each one of the connected clamp member portions 18a, 20a generally axially toward the other one of the clamp member portions 20a, 18a so as to compress the inner portion 14a of the base 14.

More specifically, the at least one coupler 22 is configured to displace each clamp member 18, 20 from a first, distal axial position D_{1 ;} D₂ (Figs. 7 and 11), at which the two clamp members 18, 20 are spaced by a first distance S toward a second axial position P_{1 ;} P₂ (Figs. 8 and 12), at which the two clamp members 18, 20 are spaced by a second, lesser distance S₂. Thereby, the base inner portion 14a is compressed between the clamp members 18, 20 during displacement from the first positions D_{1 ;} D₂ toward the second positions P_1; P₂. As the base inner portion 14a is compressed axially, the elastomeric material of the base 14 pushes or bulges radially such that the integrally connected base outer portion 14b is displaced or pushed radially outwardly toward the housing inner surface 2a, as indicated by arrows in Figs. 2, 8 12 and 14. The coupler 22 is further configured to alternatively displace each clamp member 18, 20 from the second position P_1; P₂ toward the first position D_1; D₂, so as to thereby release compression on the base inner portion 14a.

As best shown in Figs. 1, 4 and 9, each one of the first and second clamp members 18, 20 preferably includes a generally circular annular body 30 extending circumferentially about the central axis Ac, the body 30 preferably having solid circular axial cross-sections (see, e.g., Figs. 3 and 6). However, the annular body 30 may alternatively have other cross- sectional shapes (e.g., tubular, elliptical, rectangular, etc.) or/and the clamp members 18, 20 be formed as two or more arcuate segments or segments of any other appropriate shape. Preferably, the at least one coupler 22 includes a plurality of couplers 22 spaced circumferentially about the central axis Ac, each coupler 22 being coupled with each one of the two annular clamp bodies 30. Specifically, each coupler first end 22a is coupled with a separate portion 18a of the first clamp member 18 and each coupler second end 22b is coupled with a separate portion 20a of the second clamp member 20a.

Referring now to Figs. 2, 5, 7, 8, 11 and 12, each first clamp member portion 18a preferably has a through-hole 32 and each second clamp member portion 20a preferably has a threaded hole 34. Alternatively, each second clamp member portion 20a may be provided with a through-hole 35 and the expander device 16 may further include a nut 37 disposed against the axially outer end of the second clamp member 20 and having a threaded hole 39, as depicted in Figs. 11 and 12. In either case, each coupler 22 preferably includes a rod 36 with head 38 proximal to the coupler first end 22a and an externally threaded portion 40 proximal to the coupler second end 22b. With this structure, the coupler rod 36 is assembled to the clamp members 18, 20 such that the rod 36 extends through the first clamp member through-hole 32, with the head 38 being disposed on an axially outer end of the first clamp member 18, and through a clearance hole 48 in the base inner portion 14a, with the rod threaded portion 40 being threadedly engaged with the second clamp member threaded hole 34. In the alternative construction shown in Figs. 11 and 12, each coupler rod 36 also extends through one of the through-holes 35 in the second clamp member 20 and the rod threaded portion 40 is threadedly engaged with the hole 39 in the proximal nut 37.

Thereafter, in either construction, the rod 36 is angularly displaceable or rotatable in a first direction (e.g., clockwise) about a central axis 36a so as displace the connected portions 18a, 20a of the first and second clamp members 18, 20 generally axially toward each other to thereby displace the base outer portion 14b generally radially outwardly. Specifically, the rod threaded portion 40 advances through the second clamp member hole 34 and causes the head 38 to pull the first clamp member portion 18a axially toward the second clamp member portion 20a, or the head 38 and the nut 37 pull both clamp member portions 18a, 20a toward each other.

Alternatively, the rod 26 is angularly displaceable in a second, opposing direction (e.g., counterclockwise) about the axis 36a so as to displace the connected clamp portions 18a, 20a generally axially away from each other to permit the base outer portion 14b to displace generally radially inwardly, i.e., due to the release of internal material stresses. That is, as the rod threaded portion 40 withdraws from the second clamp member threaded hole 34, the coupler head 38 displaces generally away from the clamp members 18, 20, thereby enabling material stresses in the compressed base inner portion 14a to displace or "push" the clamp member portions 18a, 20a axially away from each other as the base 14 returns to an uncompressed state.

Although preferably formed as a threaded rod 36, without or with a nut 37, the one or more couplers 22 may be formed in any other appropriate manner. For example, the coupler may be formed as a separate clamp having two jaws (not shown) each engaged with a separate one of the clamp members 18, 20, as a turn-buckle device, etc. The present invention covers the coupler structures disclosed herein and any other structures capable of displacing the clamp members 18, 20 axially toward each other and alternatively at least permitting the clamp members 18, 20 to displace axially away from each other.

Referring to Figs. 2, 3, 5-8 and 10-12, the base 14 preferably includes a first annular groove 44 extending generally axially inwardly from the first axial side 15A and a second annular groove 46 extending generally axially inwardly from the second axial side 15B. A plurality of clearance holes 48 extend between the two grooves 44, 46 and are spaced apart circumferentially about the axis A_c. By providing the two grooves 44, 46, the base inner portion 14a is defined generally between the two grooves 44, 46 and the base outer portion 14b is defined generally between and above the grooves 44, 46. Further, the first clamp member 18 is disposed at least partially within the first annular groove 44 and the second clamp member 20 is preferably disposed at least partially within the second groove 46, with each coupler rod 36 extending through a separate one of the clearance holes 48. However, the base 14 may alternatively be formed without any grooves, such that the clamp members 18, 20 are disposed against the radial surfaces 47 on each axial end 15A, 15B, respectively, in which case the base inner portion 14a is defined as the portion of the base 14 between the clamp members 18, 20.

With the preferred grooves 44, 46, the base 14 is defined or formed generally as inner and outer annular rims 50, 52 and a central annular web 54 extending generally radially between the rims 50, 54, as indicated in Fig. 10. The web 54 provides the base inner portion 14a and the outer rim 52 provides the base outer portion 14b engageable with the housing inner surface 2a. Further, the lip 12 is formed as a generally cantilever-like body 56 having a first axial end 56a integrally formed with the base inner rim 50 and a second, free axial end 56 providing an inner circumferential sealing surface 58. As such, the lip 12 and base 14 are preferably of one-piece construction and provided by a generally annular extruded elastomeric body 59, such that the lip 12 is also formed of the same elastomeric material as the base 14. Alternatively, the lip 12 may be separately formed from the base 14 and connected thereto by any appropriate means, such as bonding, a friction fit, fasteners, etc, and may be formed of a different elastomer than the base 14 or of any other appropriate material, such as a rigid polymer (e.g., PTFE), a metallic material (e.g., bronze), etc.

Further, the free end 56b of the cantilever body 56 is preferably generally triangular or wedge-shaped and has converging faces 60, 62 intersecting at an edge 64 that provides the sealing surface 58. Furthermore, the seal assembly 10 preferably additionally comprises a generally annular biasing member 66, most preferably a garter spring, disposed generally about the lip second axial end 56b. The biasing member 66 is configured to bias the second end radially inwardly toward the shaft 1 so as to maintain sealing engagement between the sealing surface 58 and the shaft outer surface la.

Although preferably formed as conventional radial lip seal as described above, the lip 12 and the base 14 may be formed in any other appropriate manner. For example, the lip 12 may be formed with a generally cylindrical portion providing the sealing surface and/or fabricated of a generally rigid polymeric material. The present invention encompasses the structures disclosed herein and all other constructions of the lip 12 and base 14 in which the seal assembly 10 is capable of functioning as generally described herein.

In any case, the seal assembly of 10 the present invention is utilized in the following manner. Referring to Figs. 13 and 14, when it is desired to install the seal assembly 10 within a particular housing 2, the seal assembly 10 with the clamp members 18, 20 located at the distal positions D_1; D₂ such that the base 14 is in a non-expanded state, is inserted into the housing bore 3 (Fig. 13) and then displaced axially along the central axis the bore 3 until located at a desired axial position P_A (Fig. 14). Then, each one of the preferred plurality of couplers 22 is angularly displaced or rotated in the first angular direction (e.g., clockwise), such as by using a socket wrench (not shown) coupled with the head 38, so as to displace the clamp members 18, 20 axially from the first, distal positions D_1; D₂ toward the second, proximal positions P_1; P₂.

During such displacement, the base inner portion 14a is compressed axially and pushed radially outwardly, causing the connected base outer portion 14b to displace radially outwardly into engagement with the housing inner surface 2a. The base 14 is then in an expanded state in which the outwardly displaced base outer portion 14b pushes or compresses against the inner surface 2a to both form a seal between the base outer surface 17 and the housing inner surface 2a and to generate a sufficient friction force to retain the seal assembly 10 axially within the bore 3.

Thereafter, when it is desired to remove the seal assembly 10 from the housing 2, each of the couplers 22 is angularly displaced/rotated in the second angular direction (e.g., counter- clockwise) such that the clamp members 18, 20 displace from the second, proximal positions P_1; P₂ toward the first, distal positions D_1; D₂. During this displacement of the clamp members 18, 20, compressive forces on the base inner portion 14a are released, such that internal material forces within the base 14 cause the base inner portion 14a to return to its original shape.

Thereby, the base inner portion 14a both expands in an axial direction and retracts in a radial direction, causing the integrally connected base outer portion 14b to displace radially inwardly away from the housing inner surface 2a. Thereby, the base outer surface 17 disengages from the housing inner surface 2a and releases the frictional forces therebetween. At this point, the seal assembly 10 may be displaced axially for removal from the housing bore 3.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as generally defined in the appended claims.

Claims

We claim:

1. A seal assembly for sealing an annular space between a shaft with an outer

circumferential surface and a housing having an inner circumferential surface, the seal assembly comprising:

a generally annular sealing lip extending circumferentially about a central axis and sealingly engageable with the shaft outer surface;

a generally annular elastomeric base disposed generally coaxially about and connected with the lip, the base having an outer circumferential surface contactable with the housing inner circumferential surface; and

an expander device configured to compress an inner portion of the base so as to displace an outer portion of the base generally radially outwardly such that the base outer surface sealingly engages the housing inner surface.

2. The seal assembly as recited in claim 1 wherein the base inner portion has two opposing axial sides and the expander device includes first and second clamp members each disposed generally against a separate one of the two base inner portion axial sides and at least one movable coupler having a first end coupled with a portion of the first clamp member and a second end coupled with a portion of the second clamp member, each coupler being configured to displace each one of the connected clamp member portions generally axially toward the other one of the clamp member portions so as to compress the inner portion of the base member.

3. The seal assembly as recited in claim 2 wherein the at least one coupler is configured to displace each clamp member from a first axial position at which the two clamp members are spaced by a first distance toward a second axial position at which the two clamp members are spaced by a second, lesser distance so as to compress the base inner portion between the clamp members and to alternatively displace each clamp from the second position toward the first position so as to release compression on the base inner portion.

4. The seal assembly as recited in claim 2 wherein each one of the first and second clamp members includes a generally annular body and the at least one coupler includes a plurality of couplers spaced circumferentially about the central axis, each coupler being coupled with each one of the two annular clamp bodies.

5. The seal assembly as recited in claim 2 wherein the first clamp member has a through- hole, the second clamp member portion has a threaded hole and the at least one coupler includes a rod with head proximal to the coupler first end and an external thread proximal to the coupler second end, the coupler rod extending through the first clamp member through-hole and the rod thread being threadedly engaged with the second clamp member threaded hole.

6. The seal assembly as recited in claim 5 wherein the rod is angularly displaceable in a first direction so as displace the connected portions of the first and second clamp members generally axially toward each other to displace the base outer portion generally radially outwardly and is alternatively angularly displaceable in a second direction so as to displace the connected clamp portions generally axially away from each other to permit the base outer portion to displace generally radially inwardly

7. The seal assembly as recited in claim 2 wherein:

the base includes a first annular groove extending generally axially inwardly from the first axial side and a second annular groove extending generally axially inwardly from the second axial side, the base inner portion being defined generally between the two grooves; and

the first clamp member is disposed at least partially within the first annular groove and the second clamp member is disposed at least partially within the second groove.

8. The seal assembly as recited in claim 7 wherein each one of the first and second clamp members includes a generally annular body and the at least one coupler includes a plurality of couplers spaced circumferentially about the central axis.

9. The seal assembly as recited in claim 1 wherein:

the base has opposing axial sides, a first annular groove extending generally axially inwardly from the first axial side and a second annular groove extending generally axially inwardly from the second axial side, the two grooves defining inner and outer rims and a central web extending generally radially between the rims, the web providing the base inner portion and the outer rim providing the base outer portion; and

the lip has a first axial end integrally formed with the base inner rim and a second, free axial end providing an inner circumferential sealing surface.

10. The seal assembly as recited in claim 8 further comprising an annular biasing member disposed generally about the lip second axial end.

11. A seal assembly for sealing an annular space between a shaft with an outer

a generally annular elastomeric base disposed generally coaxially about and connected with the lip, the base having a two opposing axial sides and an outer circumferential surface contactable with the housing inner circumferential surface; and

an expander device including first and second clamp members each disposed generally against a separate one of the two base inner portion axial sides and at least one coupler having a first end coupled with a portion of the first clamp member and a second end coupled with a portion of the second clamp member, each coupler being configured to displace each one of the connected clamp member portions generally axially toward the other one of the clamp member portions to compress an inner portion of the base so as to displace an outer portion of the base generally radially outwardly such that the base outer surface sealingly engages the housing inner surface.

12. The seal assembly as recited in claim 11 wherein the at least one coupler is configured to displace each clamp member from a first axial position at which the two clamp members are spaced by a first distance toward a second axial position at which the two clamp members are spaced by a second, lesser distance so as to compress the base inner portion between the clamp members and to alternatively displace each clamp from the second position toward the first position so as to release compression on the base inner portion.

13. The seal assembly as recited in claim 11 wherein each one of the first and second clamp members includes a generally annular body and the at least one coupler includes a plurality of couplers spaced circumferentially about the central axis, each coupler being coupled with each one of the two annular clamp bodies.

14. The seal assembly as recited in claim 11 wherein the first clamp member has a through- hole, the second clamp member portion has a threaded hole and the at least one coupler includes a rod with head proximal to the coupler first end and an external thread proximal to the coupler second end, the coupler rod extending through the first clamp member through-hole and the rod thread being threadedly engaged with the second clamp member threaded hole.

15. The seal assembly as recited in claim 14 wherein the rod is angularly displaceable in a first direction so as displace the connected portions of the first and second clamp members generally axially toward each other to displace the base outer portion generally radially outwardly and is alternatively angularly displaceable in a second direction so as to displace the connected clamp portions generally axially away from each other to permit the base outer portion to displace generally radially inwardly

16. The seal assembly as recited in claim 11 wherein:

17. The seal assembly as recited in claim 16 wherein each one of the first and second clamp members includes a generally annular body and the at least one coupler includes a plurality of couplers spaced circumferentially about the central axis.

18. The seal assembly as recited in claim 11 wherein: