MULTIPLE PIECE SEAL RING ASSEMBLY

Abstract

A sealing system for sealing a cylindrically shaped surface containing a first annular seal and a second annular seal. Each annular seal has a gap penetrating from the outer diameter to the inner diameter. The angle of the gap in the first annular seal and the angle of the gap in the second annular seal and the arrangement of the seals relative to an expander ring and a biasing ring minimizes leakage without the need for an anti-rotation pin or other means that would significantly decrease efficiency and reliability.

Claims

1. A sealing system for sealing a cylindrically shaped surface, the sealing system comprising: (a) a first annular seal having a first axial width extending between a first axial face and a second axial face, the first annular seal having a first radial thickness extending between a first inner circumferential surface to a first outer circumferential surface, a first slit extending through the first annular seal from the first axial face to the second axial face, the first slit having a length greater than the first radial thickness, the first slit extending from the first inner circumferential surface to the first outer circumferential surface in a first direction; (b) a second annular seal having a second axial width extending between a third axial face and a fourth axial face, the second annular seal having a second radial thickness extending between a second inner circumferential surface to a second outer circumferential surface, a second slit extending through the second annular seal from the third axial face to the fourth axial face, the second slit extending from the second inner circumferential surface to the second outer circumferential surface in a second direction, the second direction being different than the first direction; (c) the first annular seal and the second annular seal each having a single piece unitary construction and being aligned coaxially with one another and with the second axial face of the first annular seal slidingly engaging the third axial face of the second annular seal so that the first annular seal and the second annular seal are rotatable relative to one another and the first slit and the second slit are locatable in a common arcuate segment thereof; (d) an expander ring being aligned coaxially with the first annular seal and the second annular seal, the expander ring engaging a portion of the first annular seal and a portion of the second annular seal, the expander ring having a third axial width that is greater than at least one of the first axial width and the second axial width; and (e) a biasing ring being aligned coaxially with the first annular seal and the second annular seal, the biasing ring engaging the expander ring and imparting a force on the expander ring to force the first annular seal and the second annular seal against a sealing surface.

2. The sealing system of claim 1, wherein the second slit has a second length greater than the second radial thickness.

3. The sealing system of claim 1, wherein the third axial width of the expander ring is about equal to a sum of the first axial width and the second axial width.

4. The sealing system of claim 1, wherein the expander ring is configured to block a radial path of fluid between the biasing ring and the first annular seal and the second annular seal.

5. The sealing system of claim 1, wherein at least one of the first slit and the second slit is linear.

6. The sealing system of claim 1, wherein at least one of the first annular seal and the second annular seal is moveable in relation to the expander ring.

7. The sealing system of claim 1, wherein the first outer circumferential surface of the first annular seal and the second outer circumferential surface of the second annular seal are exterior cylindrical sealing surfaces; and the first inner circumferential surface of the first annular seal and the second inner circumferential surface of the second annular seal are interior cylindrical surfaces that engage a support surface of the expander ring.

8. The sealing system of claim 1, wherein the expander ring is annealed such that it exerts no force on the sealing rings when in an installed position.

9. The sealing system of claim 1, wherein the first inner circumferential surface and the second inner circumferential surface are interior cylindrical sealing surfaces; and the first outer circumferential surface of the first annular seal and the second outer circumferential surface of the second annular seal engage a support surface of the expander ring.

10. The sealing system of claim 1, wherein the biasing ring is a canted coil spring.

11. A piston and cylinder assembly comprising: a cylinder having a cylindrical interior sealing surface; a piston disposed at least partially in the cylinder and in sliding relation therewith, the piston having a groove extending radially inward into and circumferentially around the piston; a sealing system comprising: (a) a first annular seal having a first axial width extending between a first axial face and a second axial face, the first annular seal having a first radial thickness extending between a first inner circumferential surface to a first outer circumferential surface, a first slit extending through the first annular seal from the first axial face to the second axial face, the first slit having a length greater than the first radial thickness, the first slit extending from the first inner circumferential surface to the first outer circumferential surface in a first direction; (b) a second annular seal having a second axial width extending between a third axial face and a fourth axial face, the second annular seal having a second radial thickness extending between a second inner circumferential surface to a second outer circumferential surface, a second slit extending through the second annular seal from the third axial face to the fourth axial face, the second slit extending from the second inner circumferential surface to the second outer circumferential surface in a second direction, the second direction being different than the first direction; (c) the first annular seal and the second annular seal each having a single piece unitary construction and being aligned coaxially with one another and with the second axial face of the first annular seal slidingly engaging the third axial face of the second annular seal so that the first annular seal and the second annular seal are rotatable relative to one another and the first slit and the second slit are locatable in a common arcuate segment thereof; (d) an expander ring being aligned coaxially with the first annular seal and the second annular seal, the expander ring engaging a portion of the first annular seal and a portion of the second annular seal, the expander ring having a third axial width that is greater than at least one of the first axial width and the second axial width; and (e) a biasing ring being aligned coaxially with the first annular seal and the second annular seal, the biasing ring engaging the expander ring and imparting a force on the expander ring to force the first annular seal and the second annular seal against the cylindrical interior sealing surface; the sealing system being disposed in the groove such that the first outer circumferential surface of the first annular seal and second outer circumferential surface of the second annular seal sealingly engage the cylindrical interior sealing surface.

12. The piston and cylinder assembly of claim 11, wherein the second slit has a second length greater than the second radial thickness.

13. The piston and cylinder assembly of claim 11, wherein the third axial width of the expander ring is about equal to a sum of the first axial width and the second axial width.

14. The piston and cylinder assembly of claim 11, wherein the expander ring is configured to block a radial path of fluid between the biasing ring and the first annular seal and the second annular seal.

15. The piston and cylinder assembly of claim 11, wherein at least one of the first slit and the second slit is linear.

16. The piston and cylinder assembly of claim 11, wherein at least one of the first annular seal and the second annular seal is moveable in relation to the expander ring.

17. The piston and cylinder assembly of claim 11, wherein the first outer circumferential surface of the first annular seal and the second outer circumferential surface of the second annular seal are exterior cylindrical sealing surfaces; and the first inner circumferential surface of the first annular seal and the second inner circumferential surface of the second annular seal are interior cylindrical surfaces that engage a support surface of the expander ring.

18. The piston and cylinder assembly of claim 11, wherein the expander ring is annealed such that it exerts no force on the sealing rings when in an installed position.

19. A shaft sealing assembly comprising: a housing having an interior area and a groove extending circumferentially around and radially outward from the interior area into the housing; a shaft having a cylindrical exterior sealing surface, the shaft disposed at least partially in the interior area and in sliding relation therewith; a sealing system comprising: (a) a first annular seal having a first axial width extending between a first axial face and a second axial face, the first annular seal having a first radial thickness extending between a first inner circumferential surface to a first outer circumferential surface, a first slit extending through the first annular seal from the first axial face to the second axial face, the first slit having a length greater than the first radial thickness, the first slit extending from the first inner circumferential surface to the first outer circumferential surface in a first direction; (b) a second annular seal having a second axial width extending between a third axial face and a fourth axial face, the second annular seal having a second radial thickness extending between a second inner circumferential surface to a second outer circumferential surface, a second slit extending through the second annular seal from the third axial face to the fourth axial face, the second slit extending from the second inner circumferential surface to the second outer circumferential surface in a second direction, the second direction being different than the first direction; (c) the first annular seal and the second annular seal each having a single piece unitary construction and being aligned coaxially with one another and with the second axial face of the first annular seal slidingly engaging the third axial face of the second annular seal so that the first annular seal and the second annular seal are rotatable relative to one another and the first slit and the second slit are locatable in a common arcuate segment thereof; (d) an expander ring being aligned coaxially with the first annular seal and the second annular seal, the expander ring engaging a portion of the first annular seal and a portion of the second annular seal, the expander ring having a third axial width that is greater than at least one of the first axial width and the second axial width; and (e) a biasing ring being aligned coaxially with the first annular seal and the second annular seal, the biasing ring engaging the expander ring and imparting a force on the expander ring to force the first annular seal and the second annular seal against the cylindrical exterior sealing surface; the sealing system being disposed in the groove such that the first inner circumferential surface of the first annular seal and the second inner circumferential surface of the second annular seal sealingly engage the cylindrical exterior sealing surface.

20. The shaft sealing assembly of claim 19, wherein the second slit has a second length greater than the second radial thickness.

21. The shaft sealing assembly of claim 19, wherein the third axial width of the expander ring is about equal to a sum of the first axial width and the second axial width.

22. The shaft sealing assembly of claim 19, wherein the expander ring is configured to block a radial path of fluid between the biasing ring and the first annular seal and the second annular seal.

23. The shaft sealing assembly of claim 19, wherein at least one of the first slit and the second slit is linear.

24. The shaft sealing assembly of claim 19, wherein at least one of the first annular seal and the second annular seal is moveable in relation to the expander ring.

25. The shaft sealing assembly of claim 19, wherein the expander ring is annealed such that it exerts no force on the sealing rings when in an installed position.

26. The shaft sealing assembly of claim 19, wherein the first inner circumferential surface and the second inner circumferential surface are interior cylindrical sealing surfaces; and the first outer circumferential surface of the first annular seal and the second outer circumferential surface of the second annular seal engage a support surface of the expander ring.

27. The shaft sealing assembly of claim 19, wherein the biasing ring is a canted coil spring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 is an end view of a piston and cylinder that features a sealing system in accordance with the invention shown sealing in a cylinder, shown with a portion of one of the annular seals cut away;

[0037] FIG. 2 is a cross sectional view of the sealing system of FIG. 1 taken across section 2-2;

[0038] FIG. 3. is an exploded view of the orientation of the angled gaps in the sealing rings of FIGS. 1 and 2;

[0039] FIG. 4 is an end view of a shaft and a ring housing that features a sealing system in accordance with the invention shown sealing against a shaft, shown with a portion of one of the annular seals cut away;

[0040] FIG. 5 is a cross sectional view of the sealing system of FIG. 4 taken across section 5-5;

[0041] FIG. 6 is an end view of an example of the prior art showing anti-rotation pin;

[0042] FIG. 7 is a top view of a prior art sealing ring with an installed state depicted in phantom;

[0043] FIG. 8 is a top diagrammatic view of the prior art sealing ring of FIG. 6 in a compressed state depicting the ring force F.sub.R;

[0044] FIG. 9A is a simplified diagram of a portion the sealing ring of FIG. 1 depicting a relaxed state of the canted coil spring; and

[0045] FIG. 9B is the diagram of FIG. 9A showing a compression force F.sub.C which causes the canted coil spring to deflect at an angle.

DETAILED DESCRIPTION

[0046] As shown in FIGS. 1-3, a sealing system for sealing a cylindrically shaped surface is designated by numeric identifier 10. The sealing system 10 is installed within a bore 2 of a housing 1. A piston 3 is centered on center point A of the bore 2 of the housing 1. In some embodiments, the piston 3 oscillates linearly within the bore 2 and is included in pneumatic valves for air operated actuators. A biasing ring 50 is disposed in a first groove 3G (depicted in FIG. 2) defined by a first outer circumferential surface 3D of the piston 3. The biasing ring 50 supports an expander ring 40, a first annular seal 20, and a second annular seal 30 within the first groove 3G (depicted in detail in FIG. 2). In the depicted embodiment, the first annular seal 20 and the second annular seal 30 radially engage and seal against the inner surface of the bore 2. The sealing system 10 eliminates the need to clock the annular seals 20, 30 in place (fix the first annular seal 20 relative to the second annular seal 30). In some embodiments, the expander ring 40 is annealed to ensure that the expander ring 40 does not exert an outward force on the annular seals 20, 30 by itself.

[0047] Referring to FIGS. 1 and 3, the first annular seal 20 has a first slit 22 extending from a first inner circumferential surface 20C to a first outer circumferential surface 20D along a first direction D1. The second annular seal 30 has a second slit 33 extending from a second inner circumferential surface 30C to a second outer circumferential surface 30D along a second direction D2. The first direction D1 is defined by a first seal angle 1, measured relative to a reference line passing through the center point A and intersecting the first direction D1 at the first inner circumferential surface 20C. The second direction D2 is defined by a second seal angle 2, measured relative to a reference line passing through the center point A and intersecting the second direction D2 at the second inner circumferential surface 30C. In the depicted embodiment, the first seal angle 1 and the second seal angle 2 are of equal magnitude but the first seal angle 1 is the opposite of the second seal angle 2.

[0048] Referring to FIG. 2, the expander ring 40 directly contacts the first inner circumferential surface 20C of first annular seal 20 and the second inner circumferential surface 30C of the second annular seal 30. The first annular seal 20 and the second annular seal 30 are arranged axially adjacent to one another within the first groove 3D. The first annular seal 20 has a first axial width W1 and a first radial thickness T1. The second annular seal 30 has a second axial width W2 and a second radial thickness T2. The first axial width W1 has substantially the same magnitude as the second axial width W2. The first radial thickness T1 has substantially the same magnitude as the second radial thickness T2. The first annular seal 20 extends the first axial width W1 between a first axial face 20A and a second axial face 20B. The second annular seal 30 extends between a third axial face 30A and a fourth axial face 30B.

[0049] The first annular seal 20, 20 and the second annular seal 30, 30 each have a single piece unitary construction (i.e., are formed as one piece with no sub-segments). The first annular seal 20, 20 and the second annular seal 30, 30 are aligned coaxially with one another. The second axial face 20B, 20B of the first annular seal 20, 20 slidingly engages (e.g., rotational sliding engagement) the third axial face 30A, 30A of the second annular seal 30, 30 so that the first annular seal 20, 20 and the second annular seal 30, 30 are rotatable relative to one another and the first slit 22, 22 and the second slit 33, 33 are locatable in a common arcuate segment thereof.

[0050] The expander ring 40 has a third width W3 and extends between a third inner circumferential surface 40C and a third outer circumferential surface 40D. In the depicted embodiment, W3 is larger in magnitude than W1 and/or W2.

[0051] Referring to FIG. 3, the first slit 22 has a first length L1 measured along the first slit 22 and the second slit 33 has a second length L2 measured along the second slit 33. In the depicted embodiment, the first length L1 and the second length L2 are substantially equal to one another. In some embodiments, the first length L1 is greater than the first radial thickness T1 and/or the second length L2 is greater than the second radial thickness T2. Referring to FIG. 2, the depicted ring assembly includes two seal rings 20, 30 having substantially the same dimensions, installed over a common expander ring 40. The depicted expander ring 40 engages at least a portion of the first annular seal 20 and a portion of the second annular seal 30. This assembly of the expander ring 40, the first annular seal 20, and the second annular seal 30 is loaded by a canted coil spring or biasing ring 50. The first slit 22 and the second slit 33 are cut at angles that prevent the complete alignment of the ring gaps that would then increase the leakage rate. Specifically, the first seal angle 1 and the second seal angle 2, depicted in detail in FIGS. 1 and 3, prevent complete alignment of the first slit 22 and the second slit 33. The depicted gap alignment eliminates the need for an anti-rotation device to prevent alignment of the gaps, as required in the prior art. In the depicted embodiment, the first annular seal 20 and/or the second annular seal 30 is moveable in relation to the expander ring 40. The location of the biasing ring 50 relative to the expander ring 40, the first annular seal 20, and the second annular seal 30 provides uniform radial loading, improving the conformance of the exterior circumferential surface of the first and second annular seal 20, 30 to the cylindrical surface of the bore 2. In the depicted embodiment, the first slit 22 and the second slit 33 are defined by linear gaps in the first annular seal 20 and the second annular seal 30. Other shapes defining the first slit 22 and/or the second slit 33 do not depart significantly from the disclosure contained herein.

[0052] Referring to FIG. 2, the biasing ring 50 engages the first outer circumferential surface 3D and the third inner circumferential surface 40C of the expander ring 40. The biasing ring 50 exerts a biasing force radially outward away from first outer circumferential surface 3D of the piston 3 against the expander ring 40. The expander ring 40 directs the biasing force through first annular seal 20 and second annular seal 30, sealing against the inside surface of the bore 2 of the housing 1. In the depicted embodiment, the biasing ring 50 is a canted coil spring. The compression of a canted coil spring is much more controllable and the size is much smaller than traditional coil springs. The combination of the biasing ring 50, the expander ring 40, the first annular seal 20, and the second annular seal 30 within the first groove 3G is unique, providing a uniform applied pressure to the annular seals 20, 30. This uniform applied pressure is necessary to minimize wear in linear oscillating applications, in which the piston 3 repeatedly oscillates along the inside surface 4 defined by the bore 2. Friction between the annular seals 20, 30 and the inside surface 4 defined by the bore 2 causes wear of the annular seals 20, 30 and/or inside surface 4. Linear oscillating applications are very sensitive to friction and wear. Any high pressure spots between the sealing ring(s) and the cylinder causes friction and more wear. Too much pressure overall also generates significant friction and wear. The biasing ring 50 incorporated into the sealing system 10 disclosed herein controls the contact pressure between the sealing system 10 and the inside surface 4 to be more uniform and to minimize the magnitude of the friction.

[0053] FIGS. 9A and 9B depict diagrams of the biasing ring 50 in the form of a canted coil spring before and after a compression force F.sub.C acts on the expander ring 40, respectively. The canted coil type biasing ring 50 is superior to a coiled spring 66 design and offers much better control over the pressure magnitude. The canted coil type biasing ring 50 exerts the force by changing angle Q9 (i.e., canting angle) relative to reference line R10, not by stretching or compression as with the traditional coil spring 66. A traditional coiled spring 66 cannot contact both the expander ring 70 and the outer circumferential surface of the piston 300. The inner surface of the coil spring 66 must be free. The compression of a long, slender coiled spring 66 cannot exert as much pressure as an element that contacts both the outer circumferential surface of the piston 300 and the inner circumferential surface of the expander ring 70. A coiled spring force F.sub.S is very limited in compression due to buckling.

[0054] FIG. 2 also depicts a radial path (RP) in which fluid flows from the housing 1, through the first annular seal 20, the second annular seal 30. In the depicted embodiment, the expander ring 40 blocks the radial path (RP) of fluid between the biasing ring 50 and the first annular seal 20 and between the biasing ring 50 and the second annular seal 30. In the embodiment depicted in FIGS. 1-3, the biasing ring 50 is coaxially aligned with the piston 3, the expander ring 40, the first annular seal 20, and the second annular seal 30.

[0055] Referring to FIGS. 4 and 5, the sealing system 10 is also compatible with ring assemblies that seal on a shaft 1. A housing 3 has an interior area 3X, located radially between the housing 3 and the shaft 1. A groove 3G extends circumferentially and radially outwards from the interior area 3X into the housing 3. The shaft 1 has a cylindrical exterior sealing surface 2 and the shaft 1 is disposed at least partially within the interior area 3X and is in sliding relation with the interior area 3X. A sealing system 10 is retained in the groove 3G such that the first inner circumferential surface 20C of the first annular seal 20 and the second inner circumferential surface 30C of the second annular seal 30 sealingly engage the cylindrical exterior sealing surface 2.

[0056] Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of the appended claims.