Crowned anti-rotation device for circumferential seals

Abstract

An anti-rotation device (10) for a circumferential seal (1) disposed within a housing (3) and having an annular body (4) and one or more openings with facing first and second sides. The device comprises at least one and preferably a plurality of lugs (12), each having a first axial end coupled to the housing (3), preferably via an annular bearing disposed within the housing (3), an opposite second axial end, inner and outer radial ends (12c, 12d), each extending axially between the first and second axial ends (12a, 12b), and opposite first and second retainer surfaces (16a, 16b), extending axially between the first and second axial ends (12a, 12b) and radially between the inner and outer radial ends (12c, 12d). At least one retainer surface (16a, 16b) is convexly curved, and each lug (12) can be at least partially disposed within the sealing opening (6) so that the convexly curved retainer surface (16a, 16b) can contact one of the sealing opening sides (6a, 6b) to prevent angular displacement of the seal (1) relative to the housing (3).

Description

Technical Field

[0001] The present invention relates to seals and, more particularly, to apparatus for preventing angular displacement of circumferential seals. Background Art

[0002] Circumferential seals are known and typically comprise an annular body disposed about a shaft or a sleeve mounted on the shaft. The seal has an inner circumferential seal which seals against the shaft or sleeve as the shaft rotates about a central axis. Some circumferential seals are "lift-off" seals which displace radially outwardly during shaft rotation to reduce wear on the seal. As the seal is typically free to "float" within the seal housing, some means must be provided to prevent angular displacement of the seal about the shaft axis. Summary of the invention

[0003] In one aspect, the present invention is an anti-rotation device for a circumferential seal disposed within a housing and having an annular body with a central axis, opposed axial ends, and at least one opening extending generally axially between the axial ends and having facing first and second sides. The anti-rotation device includes at least one lug having a first axial end coupled to the housing, an opposed second free axial end, and inner and outer radial ends, each extending axially between the first and second axial ends. Opposing first and second retainer surfaces extend axially between the first and second axial ends and radially between the inner and outer radial ends, at least one of the first and second retainer surfaces being generally convexly curved. At least one lug may be at least partially disposed within at least one seal opening such that the convexly curved retainer surface may contact one of the first and second seal opening sides to prevent angular displacement of the seal relative to the housing.

[0004] In another aspect, the present invention is also an anti-rotation device for a circumferential seal, the seal being disposed in a housing and having an annular body with a central axis, opposed axial ends, and at least one opening, the opening extending generally axially between the axial ends and having facing first and second sides. The anti-rotation device includes a generally annular carrier disposed in the housing and axially spaced from the seal, the carrier having opposed first and second axial faces. At least one lug extends axially from the first face of the carrier, the lug having a first axial end coupled to the carrier, an opposed second free axial end, and inner and outer radial ends, each extending axially between the first and second axial ends. Opposed first and second retainer surfaces extend axially between the first and second axial ends and radially between the inner and outer radial ends, at least one of the first and second retainer surfaces being generally convexly curved. At least one lug may be at least partially disposed within at least one seal opening such that the convexly curved retainer surface may contact one of the first and second seal opening sides to prevent angular displacement of the seal relative to the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The foregoing summary of the invention and detailed description of the preferred embodiments of the invention will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, there are shown in the accompanying drawings presently preferred schematic embodiments. However, it should be understood that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

[0006] Figure 1 is an axial cross-sectional view of a first configuration anti-rotation device engaged with a seal of a single seal assembly, the seal being shown disposed about a shaft and within a housing;

[0007] Figure 2 is shown by the biasing spring Figure 1 An axial cross-sectional view of a single sealing assembly;

[0008] Figure 3 is a cutaway enlarged bottom view of a first structure retainer device showing a lug engaging a single seal;

[0009] Figure 4 is a perspective view of a first structure retainer device;

[0010] Figure 5 is an axial cross-sectional view of a second configuration anti-rotation device engaged with two seals of a dual or tandem seal assembly, the seals being shown disposed within a housing;

[0011] Figure 6 is a cutaway enlarged bottom view of a second structure retainer device showing two lugs, each lug engaging a separate one of the two seals;

[0012] Figure 7 is a perspective view of a second structure retainer device;

[0013] Figure 8 is a perspective view from the top of the detachable lug of the retainer device;

[0014] Fig. 9 is from Figure 8 A perspective view of the bottom of the lug;

[0015] Fig.10 yes Figure 8 A side view of the lug;

[0016] Fig.11 yes Figure 8 A top view of the lug;

[0017] Fig.12 yes Figure 8 An axial cross-sectional view of the lug showing installation in a carrier;

[0018] Fig.13 is a perspective view from the top of a lug which is integral with a carrier of a retainer device;

[0019] Fig.14 is a radial cross-sectional view of a preferred double curved lug of a retainer device;

[0020] Fig.15 is a radial cross-section of an alternative single curved lug of a retainer device;

[0021] Fig.16A and 16B , collectively referred to as FIG. 16 , is a radial cross-sectional view of the lug engaging the seal, showing the seal in Fig.16A In the initial position, Fig. 16B In a radially outwardly displaced position;

[0022] Fig.17A and 17B , collectively referred to as FIG. 17 , is a radial cross-sectional view of a lug engaging a seal, the lug being in an angularly misaligned or “warped” position, and showing the seal in a Fig.17A In the initial position, Fig. 17B in a radially outwardly displaced position; and

[0023] Fig.18 is a more schematic radial cross-section of the lug, showing the dimensions for calculating the optimum radius of the retainer surface. DETAILED DESCRIPTION

[0024] Certain terms are used in the following description for convenience only and are not limiting. The words "inward", "inwardly" and "outwardly", "outwardly" refer to directions toward and away from a designated centerline or geometric center of the described element, respectively, and the specific meaning is easily understood from the context of the specification. In addition, as used herein, the words "connect" and "couple" are intended to include a direct connection between two components without any other components between them and an indirect connection between components with one or more other components inserted therein, respectively. The term includes the words specifically mentioned above, their derivatives, and words of similar meaning.

[0025] Reference will now be made in detail to the drawings, wherein like reference numerals are used to refer to like elements throughout. Figure 1-18 In the figure, an anti-rotation device 10 for a circumferential seal 1 is shown, the seal 1 having an inner circumferential sealing surface 1a for rotating about a central axis A. S The seal 1 is disposed within a generally annular housing 3 and includes a central axis A. C (It is parallel to the shaft axis A S The annular body 4 has an essentially collinear structure and opposite axial ends 4a, 4b, the end 4b being configured to seal against the radial surface 3a of the housing 3, such as Figure 1-3 As shown. Preferably, the seal annular body 4 is formed by a plurality of arcuate seal segments (not shown) having opposite circumferential ends, each end being coupled to a separate corresponding end of two adjacent seal segments to form the annular body 4. Most preferably, the seal 4 is a "lifting" seal that can be displaced radially outward from the outer surface of the inner member 2 to reduce friction on the sealing surface 1a. Thus, each seal segment is provided with one or more lifting ramps 5 ( Figure 6 ), or the shaft 2 (or the flow channel (not shown) arranged on the shaft 2) is provided with a plurality of lifting grooves (not shown) to generate radially outward forces on each sealing segment. In addition, the sealing annular body 4 also has at least one opening 6, which extends substantially axially between the axial ends 4a, 4b and has first and second sides 6a, 6b facing each other, such as Figure 1 , 3 , 6, 16 and 17, and preferably has at least one opening 6 in each sealing segment (not shown).

[0026] The retainer device 10 basically comprises at least and preferably a plurality of lugs 12, each lug having a first axial end 12a coupled to the housing 3 directly or via a carrier 14 as described below, and an opposite second free axial end 12b disposed within a single one of the sealing openings 6, as described below. Each lug 12 also has inner and outer radial ends 12c, 12d, respectively, each extending axially between the first and second axial ends 12a, 12b, and opposite first and second retainer surfaces 16A, 16B, each extending axially between the first and second axial ends 12a, 12b and radially between the inner and outer radial ends 12c, 12d. At least one and preferably both of the first and second retainer surfaces 16A, 16B are "crowned" or generally convexly curved so that the two retainer surfaces 16A, 16B are convexly curved relative to the seal axis A. S In the relative circumferential direction from the lug centerline L C Thus, each lug 12 has a thickness t defined between the first and second retainer surfaces 16A, 16B. L , the thickness is at a minimum value t near at least one and preferably both of the inner and outer radial ends 12c, 12d. Lmin and a maximum value t at a position approximately midway between the inner and outer radial ends 12c, 12d and preferably centered therebetween. Lmax The radial changes between Fig.14 and 15 shown.

[0027] Preferably, for reasons discussed below, at least one of the convexly curved retainer surfaces 16A and / or 16B has a relatively flat or "shallow" curvature. Specifically, each convexly curved retainer surface 16A, 16B is preferably formed to have a radius r, respectively. RA 、r RB The radius of the generally cylindrical surface portion is about the center line L of the lug. C The opposite sides and spaced apart from each other are separated from the axis A RA , A RB Extend. Select each radius r RA 、r RB The surfaces 16A and / or 16B may be of sufficient size to provide relatively shallow or "flatter" convexly curved surfaces 16A and / or 16B to eliminate disadvantages of prior art anti-rotation devices as described below.

[0028] Preferably, each radius r RA and / or RB The size is H L and θ T is a function of , and is best calculated using the following formula:

[0029] r R =(H L 2 +4C P 2 ) / 8C P

[0030] Where: H L = Lug height = Radial distance between 12c and 12d

[0031] C P =(H L / 2)*tanθ T

[0032] θ T = Total angular deviation = θ L+ θ O

[0033] θ L = Lug and center axis A S Angular deviation

[0034] θ O = opening side 6a or 6b and axis A S Angular deviation

[0035] Using the preferred lug height H L (See Fig.18 ) and the desired maximum angular deviation θ L and θ O , calculate the optimum size of the radius of each retainer surface 16A, 16B. Most preferably, the lug 12 is formed so that the retainer surface radius r RA and / or RB Height H L The ratio is r R / H L In the range between about 2.4 to about 2.8.

[0036] Reference Figure 1 , 5 , 16 and 17, at least one lug 12 may be at least partially disposed within at least one sealing opening 6 so that the convexly curved retainer surface 16A or 16B may contact one of the first and second sealing opening sides 6a or 6b to prevent the seal 1 from moving about the central axis A C More specifically, each of the one or more lugs 12 is angularly displaced relative to the shaft axis A due to the coupling of the first lug end 12a with the fixed housing 3. S The seal body 4 is fixed so that any torque on the seal body 4 pushes one seal opening side 6a or 6b against the facing lug retainer surface 16a, 16b of the fixing lug 12, thereby preventing the seal 1 from rotating about the central axis A.C In addition, when the shaft 2 can only rotate around the axis A C When rotating in one direction, the lug 12 may be formed with only one convexly curved contact surface 16A or 16B, such as Fig.15 As shown, since torque on the seal 1 can only occur in the direction of rotation, the lug 12 will engage on only one seal opening side 6a or 6b. However, when the seal 12 can rotate in either direction, preferably both retainer surfaces 16A, 16B are convexly curved, such as Figure 8 , 9 , 11, 14, 16 and 17 are best shown because the sealing opening side 6a or 6b can engage on the lug 12 to prevent angular displacement.

[0037] Furthermore, since the seal 1 is preferably a lifting seal, each sealing segment must be able to move relative to the shaft center axis A. S 16B. The seal segments 12 are displaced radially outward and alternatively radially inward. During such radial movement of the seal segments, at least one of the sides 6a, 6b of each segment opening 6 slides on the corresponding lug retainer surface 16A or 16B, depending on the direction of the torque T on the seal 1. In order to eliminate the significant problems of the prior art anti-rotation devices as described below, each lug 12 is constructed so that the radially and axially extending central contact portion 17 of each convexly curved retainer surface 16A and / or 16B engages on the proximal facing one of the first and second seal opening sides 6a, 6b, respectively, while the remainder of the curved retainer surface 16A, 16B is circumferentially (i.e. about the central axis A) with one seal opening side 16A, 16B. C ) are spaced apart, as shown in Figures 16 and 17.

[0038] When each lug 12 is substantially angularly aligned with the seal 1, the central contact portion 17 is generally centered between the lug radial ends 12c, 12d, as shown in Figure 16. However, when the lug 12 is angularly deflected or "warped" relative to the seal 1, the central contact portion 17 is located closer to one of the lug radial ends 12c or 12d, as shown in Figure 17. In any case, each seal opening side 6a and / or 6b slides primarily on the relatively shallow retainer surface central portion 17, so that the contact pressure is distributed over a larger area of ​​the seal sides 6a, 6b, as shown in Figures 16 and 17.

[0039] This greater contact area is superior to the more linear contact of the cylindrical pins of the prior art devices, which ultimately results in erosion of the seal material until the pin becomes embedded in the seal, thereby inhibiting or preventing radial movement of the seal, and in some cases rupturing it. Additionally, because the sealing contact occurs in the central portion 17 of each convexly curved retainer surface 16A and / or 16B, and the resulting circumferential spacing of the radial ends 12c, 12d from the seal 1, contact with the relatively narrow or sharp edge 19 at the lug radial ends 12c, 12d is prevented. In prior art anti-rotation devices having rectangular rods or blades, such edge contact erodes the material of the seal and results in embedding the rod / blade into the seal, which also inhibits / prevents radial movement of the seal.

[0040] Reference Figure 8-12 Each of the one or more lugs 12 comprises a substantially rectangular solid body 30, wherein two largest faces 30a, 30b provide the retainer surfaces 16A, 16B, two rectangular faces 30c, 30d provide the inner and outer radial ends 12c, 12d, respectively, and at least one end face 30e provides the second free axial end 12b. In the case of a preferred lug 12 having two convexly curved retainer surfaces 16A, 16B, the body 30 has a radial cross section with a substantially truncated ellipse, such as Fig.14 , 16 and 17. Figure 8-12 In some of the illustrated structures, each lug 12 is a separate component from the carrier 14 or the housing 3, whether permanently attached to either component or removably connected to either component, and includes another end face 30f and a coupling protrusion 32 extending generally axially from the end face 30f. The protrusion 32 of each lug 12 is preferably cylindrical and can be disposed in a separate coupling opening 15 (not shown) of the carrier 14 or the housing 3 (structure not shown). Fig.12 )Inside.

[0041] In such Fig.13 In other constructions shown, the first axial end 12a of each lug 12 is integrally formed with the carrier 14 (as shown) or with the housing (not shown) such that the rectangular body 30 does not include an identifiable face opposite the end face 30e. In addition, at least the retainer surface 16A, 16B of each lug 12 and preferably the entire body 30 and preferably the surface of the carrier 14 are coated with a friction reducing material, most preferably high phosphorus chemical nickel, but may be any other suitable coating material.

[0042] Now refer to Figure 1-7 and 13, the retainer device 10 preferably also includes a carrier 14, which is arranged in the housing 3 and is coupled thereto, so that the carrier 14 is circumferentially connected to the shaft axis A. SThe carrier 14 is axially spaced from the seal 12 and is also disposed at Figure 5-7 The carrier 14 includes a generally annular body 40, which is preferably formed as a generally washer-shaped circular plate and has a central axis 43 and opposed first and second axial faces 44A, 44B. The first end 12a of each lug 12 is removably coupled to the carrier 14, permanently attached to the carrier 14, or integrally formed with the carrier 14; Figure 1-4 In the single seal assembly shown, the lug 12 extends only from the carrier first face 44A and is Figure 5-7 In the double or tandem spring assembly shown, the lugs 12 extend from both faces 44A, 44B. In addition, the plurality of lugs 12 extend around the carrier center axis 43 and thus around the shaft axis A. C Circumferentially spaced apart, with each lug 12 being at least partially disposed in a single one of the plurality of sealing openings 6. Although a carrier 14 is preferred, the retainer device 10 may alternatively be formed without a carrier, in which case the first axial end 12a of each lug 12 is directly connected to the housing 3 by any suitable means (e.g. integrally formed or removably or permanently attached).

[0043] In addition to the "carrying" lugs 12, the carrier 14 also serves as a spring retainer; more specifically, the carrier first axial face 44A provides a spring retaining surface 46 for the end 50a of at least one spring 50, which is used in a single seal assembly ( Figure 2 ) in the axial bias seal 2, in the double seal assembly, the two bearing surfaces 44A, 44B are multiple springs 50 ( Figure 6 ) provides a separate retaining surface 46 at the end 50a. Most preferably, except for the structure of the lug 12, the retainer device 10 is substantially similar to the retainer device disclosed in U.S. Patent Application Serial No. 15 / 908109 filed on February 28, 2018, the entire contents of which are incorporated herein by reference.

[0044] Those skilled in the art will appreciate that changes may be made to the above embodiments without departing from the broad inventive concept of the present invention. Therefore, it should be understood that the present invention is not limited to the specific embodiments disclosed, but is intended to cover modifications within the spirit and scope of the present invention as generally defined in the appended claims.

Claims

1. An anti-rotation device (10) for a circumferential seal (1), the seal (1) being arranged in a housing (3) and having a central axis (A S ), an annular body (4) having opposite axial ends (4a, 4b) and at least one opening (6) extending generally axially between the axial ends (4a, 4b) and having facing first and second sides (6a, 6b), the device (10) comprising: at least one lug (12) having a first axial end (12a, 12b) coupled to the housing (3), an opposed second free axial end, inner and outer radial ends (12c, 12d), each extending axially between the first and second axial ends (12a, 12b), and opposed first and second retainer surfaces (16a, 16b) extending axially between the first and second axial ends (12a, 12b) and radially between the inner and outer radial ends (12c, 12d), at least one of the first and second retainer surfaces (16a, 16b) being generally convexly curved, the at least one lug (12) being at least partially disposed within the at least one seal opening (6) such that the convexly curved retainer surface (16a, 16b) is contactable with one of the first and second seal opening sides (6a, 6b) to prevent angular displacement of the seal (1) relative to the housing (3); wherein the at least one lug (12) is configured such that an axially extending central portion of at least one convexly curved retainer surface (16a, 16b) engages one of the first and second sealing opening sides (6a, 6b), while the remainder of the curved retainer surface (16a, 16b) is circumferentially spaced from one of the sealing opening sides (6a, 6b).

2. The anti-rotation device according to claim 1, wherein: The at least one lug (12) has a thickness between the first and second retainer surfaces (16a, 16b) that varies radially between a minimum value proximate at least one of the first and second radial ends (12c, 12d) and a maximum value at a central location between the first and second radial ends (12c, 12d).

3. The anti-rotation device according to claim 1 or 2, wherein: The lug (12) has a centerline extending between first and second axial ends (12a, 12b), and at least one convexly curved retainer surface (16a, 16b) is formed as a portion of a generally cylindrical surface having a radius extending from an axis spaced from the lug centerline.

4. The anti-rotation device according to claim 3, wherein: The lug (12) has a height between lug inner and outer radial ends (12c, 12d), and the lug (12) is formed such that a ratio of a radius of a retainer surface (16a, 16b) to lug height is in a range between about 2.4 and about 2.

8.

5. The anti-rotation device according to claim 1 or 2, wherein: Each of the first and second retainer surfaces (16a, 16b) is convexly curved.

6. The anti-rotation device according to claim 5, wherein: The at least one lug (12) has a centerline extending between first and second axial ends (12a, 12b), and each of the first and second retainer surfaces (16a, 16b) extends outwardly from the centerline in opposite circumferential directions relative to the seal axis.

7. The anti-rotation device according to claim 1 or 2, wherein: A first axial end of the at least one lug (12) is directly connected to the housing (3) or to a carrier disposed in the housing (3).

8. The anti-rotation device according to claim 1 or 2, further comprising a substantially annular carrier arranged in the housing (3), the first axial end of the at least one lug (12) being detachably connected to the carrier, permanently attached to the carrier or integrally formed with the carrier.

9. The anti-rotation device according to claim 1 or 2, wherein: The at least one lug (12) comprises a central axis (A S ) A plurality of circumferentially spaced lugs (12), each of the plurality of lugs (12) being at least partially disposed within a single one of the plurality of sealing openings (6).

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