Axial shaft seal ring and seal arrangement

Abstract

An axial shaft seal ring has a holding portion and a sealing portion, which are connected to one another via an elastically deformable sealing membrane. The sealing membrane has a plurality of spatial structure areas R in the circumferential direction of the shaft seal ring, which serve as a circumferential reserve of the sealing membrane. As a result of a centrifugal force F.sub.R accompanying a rotational movement of the shaft seal ring around the central axis thereof and acting on the sealing membrane, an expansion of the sealing membrane in a radial direction is effected at least in the spatial structure areas, in such a manner that the sealing portion is acted upon by the sealing membrane with an axially directed pull force F.sub.Z, which is directed opposite to the pressing force F.sub.A.

Claims

1. An axial shaft seal ring, comprising: a holding portion, which can be arranged in a statically sealing manner on a shaft rotatable around a rotational axis; and a sealing portion for a dynamically sealing abutment against a sealing surface in an axial direction relative to a central axis of the axial shaft seal ring; wherein the holding portion and the sealing portion are connected to each other via an elastically deformable sealing membrane which extends from the holding portion in a radial direction towards the sealing portion and by means of which the sealing portion can be pretensioned against the sealing surface with a pressing force F.sub.A; wherein the sealing membrane has a plurality of spatial structure areas R in the circumferential direction of the shaft seal ring, which serve as a circumferential reserve of the sealing membrane; wherein an expansion of the sealing membrane in a radial direction is effected in the spatial structure areas R by a centrifugal force F.sub.R, which is accompanied by a rotational movement of the shaft seal ring around the central axis thereof and acts on the sealing membrane, in such a manner that the sealing portion is acted upon by the sealing membrane with an axially directed pull force F.sub.Z, which is directed opposite to the pressing force F.sub.A; wherein the sealing portion is dimensionally stable or stabilized in the shape thereof in comparison with the sealing membrane with respect to the centrifugal forces F.sub.R occurring during the operational use of the axial shaft seal ring, wherein the sealing portion of the axial shaft seal ring is stiffened by a support ring in order to counteract a radial expansion of the sealing portion during a rotational movement of the axial shaft seal ring around the central axis thereof.

2. The axial shaft seal ring according to claim 1, wherein the spatial structure areas R comprise folds of the sealing membrane.

3. The axial shaft seal ring according to claim 1, wherein the spatial structure areas R comprise recesses and/or bulges of the sealing membrane.

4. The axial shaft seal ring according to claim 3, wherein the recesses at least partially have a polygonal, an elliptical, an oval or a circular basic shape.

5. The axial shaft seal ring according to claim 1, wherein the support ring surrounds the sealing portion on the outside in a radial direction.

6. The axial shaft seal ring according to claim 5, wherein the sealing portion and the support ring are formed integrally with one another, bonded together or are formed as a multi-component injection-molded part.

7. The axial shaft seal ring according to claim 5, wherein the sealing portion is arranged clamped and held clamped in the support ring.

8. The axial shaft seal ring according to claim 1, wherein the holding portion, the sealing membrane and the sealing portion are formed integrally with one another.

9. The axial shaft seal ring according to claim 1, wherein the support ring is made of a plastic material, of metal, of ceramic or of a composite material.

10. The axial shaft seal ring according to claim 1, wherein the sealing membrane, on the inside in the radial direction, is provided with at least one mass member, with a plurality of mass members, by means of which the radial expansion of the sealing membrane is assisted during a rotational movement of the shaft seal ring.

11. The axial shaft seal ring according to claim 1, wherein the holding portion comprises a tensioning or holding ring.

12. The axial shaft seal ring according to claim 1, wherein the sealing portion has at least one sealing edge or a plurality of sealing edges.

13. The axial shaft seal ring according to claim 1, wherein the sealing membrane consists of a viscoplastic or of a rubber-elastic deformable material.

14. A sealing arrangement comprising a shaft housing and the shaft rotatable relative to the shaft housing around the rotational axis, and the axial shaft seal ring according to claim 1 for sealing a sealing gap formed between the shaft housing and the shaft, wherein the axial shaft seal ring is mounted non-rotatably on the shaft and abuts sealingly with the sealing portion thereof against the sealing surface of the shaft housing in the axial direction relative to the central axis of the shaft seal ring.

15. The sealing arrangement according to claim 14, wherein the sealing membrane is associated with a stop surface, on which the sealing membrane of the shaft seal ring is supported radially on the outside when the shaft reaches a predetermined rotational speed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a sealing arrangement having a shaft, a shaft housing and an axial shaft seal ring for sealing a sealing gap formed between the shaft and the shaft housing, wherein the axial shaft seal ring has a holding portion arranged to be statically sealed on the shaft and a sealing portion, which abuts in a sealing manner against a sealing surface of the shaft housing in axial direction and which is connected to the holding portion via a sealing membrane, wherein the sealing membrane can be activated by centrifugal forces and, in order to relieve the sealing portion, with the shaft at rest, i.e. not rotating, in a sectional view;

(3) FIG. 2 is the sealing arrangement according to FIG. 1 with the shaft rotating and the sealing membrane activated by centrifugal force acting on the sealing membrane for axially directed relief of the sealing portion of the axial shaft seal ring relative to the sealing surface, in a sectional view;

(4) FIG. 3 is the sealing arrangement according to FIG. 1 at maximum rotational speed of the shaft and having the sealing portion spaced from the counter surface in the axial direction, which results in a cancellation of the force F.sub.A;

(5) FIG. 4 is a further sealing arrangement in which the sealing membrane of the axial shaft seal ring in the neutral position thereof has a different shape than the sealing membrane shown in FIG. 1, with the shaft at rest and in a sectional view;

(6) FIG. 5 is an embodiment of a sealing membrane of an axial shaft seal ring as shown in FIGS. 1 to 4, in a sectional side view;

(7) FIG. 6 is the sealing membrane according to FIG. 5 in a perspective partial view;

(8) FIG. 7 is a further embodiment of a sealing membrane of an axial shaft seal ring as shown in FIGS. 1 to 4, in a sectional side view;

(9) FIG. 8 is the sealing membrane according to FIG. 7 in a further sectional side view;

(10) FIG. 9 is the sealing membrane according to FIG. 7 in a sectional detailed perspective view;

(11) FIG. 10 is a further embodiment of a sealing membrane of an axial shaft seal ring as shown in FIGS. 1 to 4, in a sectional detailed perspective view;

(12) FIG. 11 is a further embodiment of a sealing membrane of an axial shaft seal ring as shown in FIGS. 1 to 4, in a sectional side view

(13) FIG. 12 is the sealing membrane according to FIG. 11 in a sectional side view; and

(14) FIG. 13 is a sealing arrangement in which the sealing membrane of the axial shaft seal ring is provided with an additional mass member on the inner side thereof, in a sectional view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(15) FIG. 1 shows a sealing arrangement 10 having a shaft 12 and having a machine part designed here as a shaft housing 14. The shaft 12 can be rotated relative to the shaft housing 14 around a rotational axis marked with 16. A sealing gap 18 is formed between the shaft 12 and the shaft housing 14. The sealing gap 18 is sealed by an axial shaft seal ring 20, the central axis 22 of which coincides with the rotational axis 16 of the shaft 12. In FIG. 1 the axial shaft seal ring 20 is shown with the shaft 12 at rest or stationary.

(16) The axial shaft seal ring 20 has a foot or holding portion 24 and a sealing portion 26, which are connected to each other via a sealing membrane 28.

(17) The sealing portion 26 abuts a counter or sealing surface 30 of the shaft housing 14 in an axial direction to the rotational axis 16. It is understood that the sealing surface 30 can also be formed on a machine part that is separate from the shaft housing 14 according to an embodiment not shown in detail in the drawing.

(18) The axial shaft seal ring 20 is arranged on the shaft 12 via the holding portion 24 in a rotationally fixed manner and held in a fixed position in the axial direction. As a result, the axial shaft seal ring can rotate together with the shaft 12 around the rotational axis 16 relative to the shaft housing 14. The holding portion 24 of the axial shaft seal ring 20 abuts the shaft 12 in a statically sealing manner. The holding portion 24 can be provided with a tensioning or holding ring 32, by means of which the holding portion 24 is held on the shaft 12 in a radial press fit. The holding portion 24 can be arranged additionally or alternatively also held in an axial press fit on the shaft 12.

(19) The sealing membrane 28 is formed on the holding portion 24 and extends outwards from the holding portion 24 in a radial direction to the central axis of the axial shaft seal ring 20. The sealing membrane 28 acts as a spring or pretensioning member by which the sealing portion 26 is elastically pretensioned in the axial direction against the sealing surface 30 by means of a pressing force F.sub.A. The sealing membrane 28 has a holding portion-side membrane segment 28a and a sealing portion-side membrane segment 28b. Here, the two segments are angled against each other and together form an angle α of, here, approximately 105°. The angle α can also be larger or smaller than 105°. The holding portion-side membrane segment 28a is arranged substantially radially to the rotational axis 16. The sealing portion-side membrane segment 28b is arranged substantially axially to the rotational axis 16.

(20) The sealing membrane 28 can be formed on the end portion 24a of the holding portion 24 pointing away from the sealing surface according to the embodiment shown in FIG. 1. This ensures a sufficiently large axial preload of the sealing portion 26 against the sealing surface 30 in a particularly compact size of the axial shaft seal ring 20. However, it is to be noted that the sealing membrane 28 can also be formed on the end portion 24b facing the sealing surface 30 or in a central portion 24c of the holding portion 24 arranged between the two end portions 24a, 24b. The sealing membrane encloses an angle β of about 75° with the rotational axis 16 of the shaft here as an example.

(21) The sealing portion 26 can be formed on the sealing membrane 28 and can be formed integrally with it or, according to the embodiment shown in FIG. 1, be designed as a separate component from the sealing membrane 28.

(22) The ring-shaped sealing portion can be arranged in a holding groove 34 of a support ring 36. The support ring 36 consists of a material that is, compared to the material of the sealing membrane 28 and preferably also the sealing portion 26, less elastically deformable or dimensionally stable. The support ring 36 can thus counteract undesired expansion of the sealing portion 26 of the axial shaft seal ring 20 during rotation of the shaft 12. This means that the sealing membrane 28 is more deformable in the radial direction by centrifugal forces F.sub.R resulting from the rotation of the shaft 12 than the sealing portion 26. Due to the aforementioned reinforcement of the sealing portion 26, it can be made of a rubber-elastic or a viscoplastic deformable material, if required. Polyolefin materials such as polytetrafluoroethylene (PTFE), polyurethane (PU) or other sealing materials familiar to those skilled in the art, such as metal or ceramic, are particularly suitable materials. The support ring 36 and the sealing portion of the axial shaft seal ring 20 can, for example, be manufactured using the 2K method. The sealing portion 26 can be formed integrally with the sealing membrane 28 according to an embodiment not shown in detail in the drawing. According to FIG. 1 the support ring 36 can surround the sealing membrane 28 in a radial direction and form a stop or support surface 38 for the sealing membrane 28.

(23) In FIG. 2 the sealing arrangement 10 is shown in the operating state with the shaft rotating. The axial shaft seal ring 20 rotates relative to the shaft housing 14 in the direction of a rotational direction marked with 40 around the rotational axis 16. A centrifugal force F.sub.R derived from the rotational movement of the axial shaft seal ring 20 acts on the sealing membrane 28. This centrifugal force F.sub.R causes an expansion of the sealing membrane 28 in a radial direction. This expansion is supported or enabled by special spatial structure areas of the sealing membrane 28, which act as a circumferential reserve of the sealing membrane 28. The spatial structure areas described above will be discussed in detail below.

(24) The sealing portion 26 of the axial shaft seal ring 20, which is stiffened in the radial direction by the support ring 36, cannot expand in the radial direction or can expand only slightly. The sealing portion 26 and the support ring 36 are consequently subjected to an axially directed pull force F.sub.Z by the radially deformed sealing membrane 28. This pull force F.sub.Z points away from the sealing surface 30 and is therefore counter to the pressing force F.sub.A with which the sealing portion 26 is pressed by the sealing membrane 28 in the axial direction against the sealing surface 30. This relieves the pressure on the sealing portion 26 which abuts tightly against the sealing surface 30. A contact surface pressure between the sealing portion 26 and the sealing surface 30 is therefore reduced.

(25) The magnitude of the centrifugal force F.sub.Z acting on the sealing membrane 28 depends on the rotational speed of the shaft 12. If the rotational speed increases, the centrifugal force F.sub.R acting on the elastically deformable sealing membrane 28 increases and with it the degree of deformation of the sealing membrane 28. If the rotational speed drops, the centrifugal forces F.sub.R are reduced accordingly and the sealing membrane 28 deforms back automatically towards the initial or neutral position thereof shown in FIG. 1. Overall, this results in a rotational speed-dependent relief of the sealing portion 26 in the axial direction. It is important to ensure that the sealing portion 26 is not moved in a radial direction along the sealing surface 30 when the rotational speed of the shaft 12 changes. Hence, the sealing portion 26 or the sealing edges 26a, 26b thereof are subjected to less mechanical stress. If necessary, the sealing membrane 28, in particular the aforementioned spatial structure areas thereof, can be designed in such a manner that the pull force F.sub.Z exceeds the pressing force F.sub.A of the sealing membrane 28 acting on the sealing portion 26 when the shaft 12 reaches a specified rotational speed. In this case the sealing portion 26 is moved away from the sealing surface 30 in (strictly) axial direction. The sealing portion 26 of the axial shaft seal ring 20 is therefore spaced apart from the sealing surface 30 when the specified rotational speed of the shaft 12 is reached, as shown in FIG. 3. In this case F.sub.A=0 applies for F.sub.A.

(26) The constructional design of the axial shaft seal ring can therefore reliably counteract friction-related mechanical and thermal overloading of the sealing portion 26. The axial shaft seal ring 20 can therefore be used even at extremely high rotational speeds of the shaft 12 of, for example, up to 40,000 rpm. Due to the functional principle of the axial shaft seal ring 20, the lifespan of the shaft seal ring 20 can be significantly improved.

(27) FIG. 4 shows a further embodiment of the sealing arrangement 10. The axial shaft seal ring 20 is shown here in the stationary operating state of the shaft 12, i.e. in the neutral state thereof. In this operating state, the sealing membrane 28 forms a more acute angle β with the rotational axis 16 than is the case with the sealing arrangement 10 shown in FIG. 1. The angle β here is approximately 60°. The angle α is approximately 120°.

(28) The extension of the sealing membrane 28 in the radial direction is smaller than the extension of the sealing membrane 28 in the axial direction. The ratio of the radial extension to the axial extension of the sealing membrane 28 can in particular be (approximately) 5:7.

(29) With the sealing arrangements 10 described above, the sealing membrane 28 can alternatively also be designed convexly bent radially outwards. In this case the two membrane segments 28a, 28b are therefore not angled against each other. In addition, the sealing portion 26 and the sealing membrane 28 of the axial shaft seal ring 20 can be formed integrally. The support ring 36 and the sealing portion 26 can be bonded together, as a 2K component or otherwise attached to each other.

(30) FIGS. 5 to 12 show various embodiments of the sealing membrane 28 of an axial shaft seal ring shown in connection with the FIGS. 1 to 4 with different spatial structure areas in a sectional and exempted representation.

(31) In FIGS. 5 and 6, the sealing membrane 28 of an axial shaft seal ring 20 is shown with the holding portion-side membrane segment 28a and the sealing portion-side membrane segment 28b in an exempted view. The spatial structure areas R of the sealing membrane 28 according to FIGS. 5 and 6 are designed in the shape of folds 42 of the sealing membrane 28, which are arranged one behind the other in the circumferential direction of the sealing membrane 28. This type of folding of the sealing membrane 28 corresponds to a so-called leporello or zigzag folding of the sealing membrane 28 in circumferential direction. 44 is the first membrane hinge and 46 is the second membrane hinge of the sealing membrane 28. The membrane hinges 44, 46 can each extend over the entire or substantially the entire sealing membrane 28.

(32) The first membrane hinges 44 of the second membrane segment 28b are arranged further out in radial direction than the second membrane hinges 46. In the area of the first holding portion-side membrane segment 28a, the first membrane hinges 44 are spaced further apart from the sealing portion 26 in the axial direction than the second membrane hinges 46.

(33) Due to the folds 42 of the sealing membrane 28, it can “unfold,” i.e. expand in radial direction, under the influence of the centrifugal force F.sub.R caused by the rotation of the shaft 12 (FIG. 1). Due to the elastic resilience inherent in the material of the sealing membrane 28, it can automatically deform back from the unfolded state to the neutral state thereof (by resting shaft) as shown in FIGS. 5 and 6.

(34) According to the sealing membrane 28 shown in sections in FIGS. 7 to 9, the spatial structure areas R, through which a circumferential reserve of the sealing membrane 28 is effected, may comprise a large number of trough-shaped recesses 48 on the outside of the sealing membrane 28. The recesses 48 can each have a polygonal basic shape. Between the recesses 48, there may be membrane webs 50 arranged in the circumferential direction of the axial shaft seal ring 20, which provide a locally limited stiffening of the sealing membrane. This allows the sealing membrane 28 to be stabilized in a predetermined shape, in particular when the shaft 12 of the sealing arrangement 10 (see FIG. 1) is at rest. The recesses 48 of the two membrane segments can alternately engage, i.e. comb with each other, in the circumferential direction of the axial shaft seal ring 20 (FIG. 1).

(35) According to the sealing membrane 28 shown in FIG. 10, the recesses 48 of the sealing membrane 28 can also be designed spirally at least in sections.

(36) In the sealing membrane 28 shown in FIGS. 11 and 12 (in neutral position), the spatial structure areas R comprise individual recesses 48 of the sealing membrane 28 having an oval, here elliptical, basic shape. The recesses 48 are arranged spaced apart in the circumferential direction of the axial shaft seal ring 20 (FIG. 1), preferably regularly. The spatial structure areas R may comprise protrusions or bulges of the sealing membrane 28 instead of the recesses 48 shown in FIGS. 11 and 12.

(37) According to the embodiment of the sealing membrane 28 shown in FIG. 13, the response of the sealing membrane 28 to rotational speed changes of the shaft 12 can be further improved by a single mass member 52 or also by a plurality of mass members 52, which is/are arranged on the sealing membrane 28. The mass member(s) 52 can be fastened to the inside or outside of the sealing membrane 28 or at least in sections embedded in the material of the sealing membrane 28. The single mass member 52 for example could be ring-shaped and in particular could be made of an elastomer. Where a plurality of mass members 52 are provided, they may be made of any material, in particular metal. If required, the mass members can be mechanically coupled to each other by elastomeric connecting parts (not shown), which are designed separately from the sealing membrane 28. By using one mass member 52 or a plurality of mass members 52, the spectrum of materials suitable for the sealing membrane 28 can be extended and/or the sealing membrane 28 can be realized with a modified, i.e. smaller or larger, wall thickness. As a result, the possible application range of the axial shaft seal ring 20 or the sealing arrangement 10 can be further extended.