Shaft seal ring and shaft assembly for high rotational speeds

Abstract

The present invention relates to a shaft seal ring (18) for sealing the medium side (H) with respect to the outside (N) of a shaft assembly (10), having a sealing section (24) with a sliding surface (32) for dynamically sealing against a sealing surface (26) of a mechanical member (14) of the shaft assembly (10) extending along a sealing axis (D) in an operating state. The sealing section (24) comprises a plurality of forming grooves (34), which are laterally delimited by a first side surface (36) arranged on the medium side and a second side surface (38) arranged on the ambient side during the operating use of the shaft seal ring (18). The forming grooves (34) have a flow cross-section (S) for a lubricating medium with a maximum part and a minimum part. Each minimum part (42) of the flow cross-section (S) of the forming grooves (34) is arranged aligned or substantially aligned with the maximum part (40) of the flow cross-section (S) of the nearest forming groove (34).

Description

Technical Field

[0001] The present invention relates to a shaft seal ring and a shaft assembly for high rotational speeds.

Background Art

[0002] Shaft assemblies are often used in practice for vehicle drive units and for drive units of power tools, machine tools, etc. In order to seal the seal gap (= bearing gap) between mechanically movable machine members relative to each other, usually one or more shaft seal rings are used. The maximum allowable rotational speed of each of the machine members to be sealed from each other by the shaft seal ring depends particularly on the material of the shaft seal ring, the operating pressure to be sealed, and the type and degree of lubrication of the dynamic seal section of the shaft seal ring. In this case, as is well known, a shaft seal ring made of FKM (= fluororubber) can basically be used at a higher rotational speed than a shaft seal ring made of NBR (nitrile butadiene rubber), etc.

[0003] In practice, in order to minimize the thermal and mechanical loads on the shaft seal ring, attempts are made to optimize the lubrication in the region of the contact zone between the dynamic seal section of the shaft seal ring and the seal surface or the opposing sliding surface. The approach pursued herein is to provide a tribological microstructure or macrostructure in the seal section of the shaft seal ring or in a structure adjacent to the shaft seal ring.

[0004] From U.S. Patent No. 4,118,856, for example, it is known that the seal section is provided with a bidirectional tribo-structure in the form of rib-shaped or web-shaped material protrusions intersecting each other. However, such a tribo-structure, based on its structural form, often suffers significant mechanical wear especially during high-speed use, which is disadvantageous for the service life of the shaft seal ring.

[0005] A molding part of a seal section of a shaft seal ring, which is rather inappropriate for high rotational speeds, is known from US Patent Application Publication No. 2007 / 0187904. This seal section here comprises a plurality of passages with a uniform flow cross-section that extend parallel to each other or obliquely to each other, intersect each other, i.e., are fluidly connected, and are partially closed and terminated. The molding part of the sliding surface of the seal section is known from German Patent Application Publication No. 10109320.

[0006] A radial shaft seal ring having a groove in which a seal section for returning the medium extends annularly is disclosed in European Patent Application Publication No. 0798498. At the bottom of the groove, a hydrodynamic acting return device that projects radially inward is provided, and this return device is formed by a wave-shaped part that extends in the circumferential direction. The wave-shaped part has an inner molding part that tapers wedge-shaped in the direction towards the medium side to be sealed. This radial shaft seal ring can be used in high-speed applications, but for example, when the crimping pressure of the shaft seal ring against the correspondingly arranged seal surface is relatively large, the return ability is quite limited.

[0007] German Patent Application Publication No. 10154789 discloses another shaft seal ring with a seal lip, and this seal lip has a sealing section for being dynamically applied to a sealing surface of a mechanical member for sealing. The sealing section has a sliding surface with a plurality of formed grooves. The formed grooves are each annularly closed in the circumferential direction of the shaft seal ring, and are defined by a first side surface arranged on the low-pressure side and a side surface arranged on the high-pressure side or the medium side in the axial direction with respect to the central axis of the shaft seal ring. The side surface of each formed groove arranged on the low-pressure side is configured in a waveform in the circumferential direction, while the side surface of each formed groove on the high-pressure side is configured straight, that is, circularly, or may be configured in a wave shape in the circumferential direction. The formed grooves surely guarantee the reliable return ability of the lubricating medium reaching the inside of the formed grooves during high-speed use. However, here too, especially when the operating pressure to be sealed is high inside or on the medium side of the seal gap, the return force of the shaft seal ring is limited.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The problem of the present invention is to provide a shaft seal ring and a shaft assembly provided with the shaft seal ring, which have further improved lubrication characteristics and return ability, and enable a further improved service life when rotating at a high speed, that is, during high-speed use, and when the operating pressure to be sealed is relatively large.

Means for Solving the Problems

[0009] The problem regarding the shaft seal ring is solved by a shaft seal ring having the features described in claim 1. The shaft assembly according to the present invention has the features described in claim 17. Preferred improvements of the present invention are described in the dependent claims.

[0010] The shaft seal ring according to the present invention enables sealing of the inner or medium side to which an operating pressure can be applied as required against the peripheral or outer side of the seal gap of the shaft assembly. The shaft seal ring has a seal section. The seal section extends along the seal axis of the shaft seal ring in the assembled or operating state of the shaft seal ring and has a sliding surface for dynamically sealing against the opposing sliding surfaces of the mechanical members of the shaft assembly. The seal section has a sliding surface provided with a plurality of tribological macrostructures in the form of formed grooves. Each of the formed grooves is arranged in the seal section axially spaced from each other with respect to the seal axis of the shaft seal ring and is configured to open towards the dynamic sliding surface (= contact surface) of the seal section. Each formed groove is laterally defined by a first passage wall or side surface arranged on the medium side and a second passage wall or side surface arranged on the peripheral side (= outer or low-pressure side) during operation of the shaft seal ring. The first side surface has a straight or substantially straight extension shape in the circumferential direction. That is, it is configured circularly with respect to the seal axis. The second side surface extends in a bidirectional manner in the circumferential direction of the shaft seal ring from each maximum portion of the flow cross-section S of the formed groove in the axial direction towards the first side surface, towards the minimum portion of the flow cross-section. In other words, the second side surface is configured such that the flow cross-section is reduced and enlarged in the circumferential direction in a predetermined section. According to the present invention, each minimum portion of the flow cross-section of one formed groove is arranged to be axially aligned or substantially aligned with the maximum portion of the flow cross-section of the closest formed groove, particularly the formed groove closest on the medium side.

[0011] In an alternative form according to the present invention, the groove depth of the formed groove or the side surface shape of the low-pressure side groove side surface of the formed groove directed towards the high-pressure side or the direction of the groove side surface on the high-pressure side changes particularly periodically in the circumferential direction of the formed groove, whereby the maximum and minimum portions of the flow cross-section can be alternately formed within the formed groove. The low-pressure side groove side surface may extend, for example, obliquely or with a rounded shape.

[0012] By aligning the minimum of the flow cross-section of the forming groove with the maximum of the forming groove arranged closest to it on the medium side in the axial direction respectively in the axial direction, one narrow sliding surface segment may be arranged between these two sections respectively. Correspondingly, a wide sliding surface segment (in the direction of the seal axis) may be formed between the maximum of the flow cross-section of the forming groove and the minimum of the flow cross-section of the forming groove located closest to it on the medium side. Thereby, during the operation and use of the shaft seal ring, extremely efficient return conveyance of the lubricant with particularly little resistance in the axial direction towards the medium side or the high-pressure side H can be achieved, and thus particularly effective lubrication and cooling of the sliding surface of the seal section can be ensured. In other words, the pulling-back ability of the shaft seal ring is further improved. Thereby, the shaft seal ring is particularly suitable for the high-speed applications mentioned at the beginning.

[0013] Furthermore, it should be noted that in this way, over the entire circumference of the shaft seal ring, for each local cross-section of the seal section, a sliding surface section of uniform or substantially uniform size can be provided for dynamically sealing the seal section against the seal surface or the opposing sliding surface of the shaft assembly. This is advantageous for both the static seal performance of the shaft seal ring and the dynamic seal performance of the shaft seal ring, especially when the operating pressure on the medium side of the lubricating medium to be sealed is relatively large, and also for the service life of the shaft seal ring.

[0014] Particularly preferably, the forming groove is configured to be closed in a ring shape in the circumferential direction of the shaft seal ring. Thereby, lubrication and cooling of the sliding surface can be ensured over the entire circumference. Thereby, it can act particularly reliably against local mechanical / thermal overload on the shaft seal ring.

[0015] According to an improved form of the present invention, at least some or all of the forming grooves may be configured such that they are completely interrupted in the circumferential direction. Thereby, the effective sliding surface of the shaft seal ring can be further enlarged, which is particularly advantageous for the sealing performance of the shaft seal ring.

[0016] Most particularly preferably, each maximum part of the flow cross-section of the forming groove is at least 2 times, preferably at least 3 times, and most particularly preferably at least 4 times the size of each minimum part of the flow cross-section. This is particularly advantageous both for the lubricant storage capacity of each forming groove during operation and for the return pumping capacity (= return capacity) of the shaft seal ring. In the case of a forming groove that is completely interrupted in the circumferential direction, it is obvious that the minimum part of the flow cross-section is zero at both ends of the forming groove.

[0017] According to a preferred embodiment of the shaft seal ring, the second side surfaces of at least some or all of the forming grooves are helical on both sides of each maximum part of the flow cross-section S of the respective forming groove, that is, with a certain gradient in the direction towards the first side surface, and extend to each minimum part of the flow cross-section of the forming groove. To that extent, the second side surfaces are configured to be straight on both sides of the maximum part up to each minimum part of the respective forming groove in the development view.

[0018] According to an alternative embodiment, the second side surfaces are curved convexly or concavely on both sides of each maximum part of the flow cross-section of the forming groove, in the direction towards the first side surface, and extend towards each minimum part of the flow cross-section of the forming groove. To that extent, the second side surfaces have an indefinite gradient on both sides of the maximum part and each minimum part. Also in the development view, the second side surfaces are curved.

[0019] According to this embodiment, the flow cross-sectional shape of the forming groove can be designed in accordance with the flow characteristics of the lubricating medium and the relative rotational speed of the mechanical member to be sealed, whereby it is possible to achieve a desired dynamic pressure of the lubricant in the region of the axial acceleration / minimum part of the forming groove that is advantageous for the return action.

[0020] According to the present invention, each forming groove may have a rounded or polygonal cross-sectional shape, or a mixed shape of these cross-sectional shapes. Thereby, the forming groove can be optimally adapted to the seal section or the thickness of the seal lip forming the seal section.

[0021] According to another embodiment of the present invention, the first side surface and / or the second side surface may have different side surface gradients from each other at least in a predetermined section with respect to the seal axis of the shaft seal ring. Thereby, it is possible to minimize the local material weakening of the seal section by the forming groove, and in the case of the second side surface, it is possible to achieve an even stronger return action of the shaft seal ring.

[0022] The first side surface arranged on the medium side or the high-pressure side and the second side surface arranged on the peripheral side of at least some or all of the forming grooves are preferably convergent radially toward the seal axis. In other words, the forming groove may taper in the direction of its radial depth extension. Thereby, on the one hand, it is possible to facilitate the axially directed return of the lubricant from one forming groove to the next. On the other hand, this provides a manufacturing technical advantage in the case of a radial seal ring configured as an injection molded part, and in particular, it simplifies the demolding of the radial seal ring and can avoid defective products. Thereby, it is also possible to minimize the material weakening of the shaft seal ring in the region of the forming groove.

[0023] The forming groove may have a radial depth with respect to the seal axis, and this radial depth varies in the circumferential direction of the shaft seal ring and is, in particular, greater than the depth at the minimum of the flow cross-section of each forming groove at the maximum of the flow cross-section. Thereby, the flow cross-section of the forming groove can be adjusted particularly efficiently even in a shaft seal ring having smaller dimensions, in particular.

[0024] According to an improved form of the invention, the axially directed return conveying capacity of the shaft seal ring is increased further by a sliding surface segment arranged between the minimum of one forming groove and the maximum of the forming groove located closest thereto being operable by the medium to be deformable radially and / or axially with respect to the remaining shaft seal ring. Thereby, the mechanical flow resistance for axially shifting the lubricating medium from one forming groove to the forming groove arranged closest on the medium side can be minimized.

[0025] According to a particularly preferred embodiment of the invention, the sealing section is formed by the sealing lip of the shaft seal ring. The sealing lip preferably extends away from the holding section of the shaft seal ring and is arranged to extend parallel or substantially parallel to the seal axis in the installed state of the shaft seal ring.

[0026] The shaft seal ring may contain or consist of a material deformable viscoelastically or elastically rubber-like, depending on its defined field of use. It is self-evident that the shaft seal ring may have a reinforcing insert (= reinforcement insert), and the reinforcing insert may preferably be embedded in or arranged in the above-mentioned holding section of the shaft seal ring.

[0027] According to the present invention, the shaft seal ring may be configured as a radial shaft seal ring or a thrust shaft seal ring. In the radial shaft seal ring, the seal axis coincides with the central axis of the radial shaft seal ring and, in the installed state, coincides with the movement axis of the mechanical member to be sealed. In the thrust shaft seal ring, the seal surface / seal axis is arranged so as to extend orthogonally to the central axis of the thrust shaft seal ring.

[0028] Preferably, the substantially straight shape according to the present invention of the first side surface includes axial modulation in the circumferential direction. The maximum amplitude of this modulation is smaller than half of the maximum amplitude of the second side surface, and in particular smaller than 1 / 4 of the maximum amplitude of the second side surface.

[0029] Preferably, the substantially aligned arrangement according to the present invention of the minimum part of one forming groove with respect to the maximum part of the forming groove located closest thereto includes a circumferential misalignment of at most half of the angular spacing between the minimum part of one forming groove and the adjacent maximum part. This misalignment makes it possible to influence the characteristics of the return action. Particularly preferably, the circumferential misalignment is about 1 / 4 of the angular spacing between the minimum part of one forming groove and the adjacent maximum part.

[0030] In the case of the present invention where the groove depth of the forming groove or the side shape of the groove side surface on the low-pressure side directed in the direction of the high-pressure side or the groove side surface on the high-pressure side of the forming groove changes periodically in the circumferential direction of the forming groove, thereby alternately forming the maximum and minimum parts of the flow cross-section in the forming groove, the forming groove may extend straight and parallel to each other or in a waveform and parallel to each other.

[0031] The shaft assembly according to the present invention has a first mechanical member in the form of a shaft and a second mechanical member surrounding the shaft. The second mechanical member may in particular be a shaft casing. The shaft and the second mechanical member are arranged spaced apart from each other while forming a seal gap (= bearing gap) and are position-adjustable relative to each other about the rotation axis.

[0032] The shaft seal ring serves to seal the medium side / inner side or high pressure side H against the seal gap or the outer side or low pressure side N of the shaft assembly. The shaft seal ring is formed in the above-described form and, with its seal section, is applied dynamically sealingly against the seal surface or the opposing sliding surface of one of the two machine members. The seal surface or the opposing sliding surface is formed by the shaft in the case of a shaft seal ring that seals on the inner side, and is formed by a machine member that surrounds the shaft, i.e., is arranged to be located radially outward, in the case of a shaft seal ring that seals on the outer side. When the shaft and the machine member move relative to each other about the axis of rotation, this promotes the return effect of the shaft seal ring with respect to the lubricant directed towards the low pressure side N or reaching between the seal section and the seal surface. The lubricant is led circumferentially along the forming groove based on the relative rotational movement between the shaft and the machine member, is pressed into the constriction of each forming groove, and is sent axially in the direction of the medium side H by the low pressure side surface of the forming groove that curves towards the inner side or the medium side. At this medium side H, the lubricant reaches the expansion of the flow cross-section of the forming groove arranged closest thereto on the high pressure side. This promotes the return pressure feeding function of the shaft seal ring in the axial direction towards the inner side or the medium side. It should be noted that the shaft seal ring has a return function for the lubricant arranged / reached in the forming groove, regardless of the direction of rotation, based on the configuration of the forming groove.

[0033] Of course, the shaft seal ring may be clamped against the seal surface by a preloading element that is elastically deformable in a rubbery manner in its dynamic seal section, i.e., with its seal lip if it exists.

[0034] Furthermore, the shaft seal ring may be arranged in an (assembly) cartridge, which simplifies the shaft seal ring and, in some cases, provides it together with another seal element known per se and can be assembled into the holding structure of the machine member or the shaft.

[0035] The seal lip of the shaft seal ring is applied to the seal surface so as to dynamically and statically seal the seal surface with its sliding surface, that is, it has a formed groove opened with respect to the seal surface.

[0036] Hereinafter, the present invention will be described in detail based on the illustrated embodiments. The illustrated and described embodiments are not to be understood as a limited listing, but rather have an exemplary character for the purpose of explaining the present invention.

Brief Explanation of Drawings

[0037]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying out the Invention

[0038] Shaft assembly 10 is shown in FIG. 1. This shaft assembly 10 can be used in many technical fields, for example, in vehicle, machine tool, power tool or drive devices of pumps and compressors. The shaft assembly 10 includes a first mechanical member in the form of a shaft 12 and a second mechanical member 14 surrounding the shaft 12. The second mechanical member 14 may be configured as, for example, a shaft casing, an assembled cartridge or the like. The shaft 12 and the mechanical member 14 are arranged spaced apart from each other while forming a bearing gap 16 or a seal gap 16, and are position-adjustable relative to each other about a rotational axis marked with reference sign L.

[0039] To seal the inner or medium side (or high-pressure side) H of the seal gap 16 with respect to the outer N of the seal gap 16, a shaft seal ring generally indicated by reference numeral 18 functions. The shaft seal ring 18 has a holding section 20, a seal lip 22 attached to or integrally formed with the holding section 20, and a seal section 24 formed by the seal lip 22. The seal lip 22 may extend axially away from the holding section 20 with respect to the central axis Z of the shaft seal ring 18. In the illustrated assembled state, the central axis Z of the shaft seal ring coincides with the rotational axis L of the shaft assembly 10. The shaft seal ring 18 is applied in its seal section 24 in this embodiment so as to dynamically seal against the opposing sliding surface or seal surface 26 of the shaft 12. The holding section 20 is disposed in a holding groove 28 of the machine member 14. The holding section 20 of the shaft seal ring 18 may be made of a material different from that of the seal lip 22. The material of the holding section 20 preferably has a larger elastic modulus than the material of the seal lip 22. The holding section 20 may include, for example, metal, particularly a plastic deformable into viscoelasticity, or a composite material, or may be made of any of these materials. Of course, the shaft seal ring may be integrally formed of, for example, a viscoelastic plastic or an elastomer.

[0040] A preloading force may be applied to the seal surface 26 of the shaft seal ring 18 by an elastically deformable preloading element 30 illustrated by a dashed line in FIG. 1, for example, in the form of a worm spring or an elastomer ring.

[0041] Sealing section 24 extends along the seal axis D of the shaft seal ring 18 in the illustrated assembled state. In this embodiment, in the case of a shaft seal ring configured as a radial shaft seal ring, the seal axis D coincides with the central axis Z of the shaft seal ring 18. When the shaft seal ring 18 is configured as a thrust shaft seal ring, the seal surface or the seal axis D is arranged in the assembled state so as to be orthogonal to the central axis Z of the shaft seal ring and to extend orthogonally to the movement axis L of both mechanical members 12, 14.

[0042] According to FIG. 1, the sealing section 24 includes a sliding surface 32 and a plurality of formed grooves 34 arranged on the sliding surface 32. The formed grooves 34 function as a tribo structure and are arranged axially spaced apart from each other with respect to the seal axis D in the assembled state. It should be noted that each formed groove 34 is configured to open radially toward the dynamic sliding surface 32 of the sealing section 24, and thus toward the seal surface 26 of the shaft 12 in the assembled state.

[0043] FIG. 2 shows a detailed portion of the sealing section 24 of the shaft seal ring 18 shown in FIG. 1 in a perspective view.

[0044] The formed grooves 34 are defined laterally by the first passage wall / surface 36 arranged on the medium side or the high-pressure side H, that is, on the high-pressure side, and the second passage wall / surface 38 arranged on the outside N, that is, on the low-pressure side, in the axial direction during the operation and use of the shaft seal ring 18. The formed grooves 34 are configured to extend annularly over the entire circumference and close on both axial sides. In other words, these formed grooves 34 do not have fluid connection passages or the like facing each other.

[0045] The first side surface 36 on the high-pressure side of the forming groove 34 has a straight or substantially straight shape in the circumferential direction, respectively. In contrast, the side surface 38 of each forming groove 34 arranged on the low-pressure side has a wavy shape in the circumferential direction of the shaft seal ring 18, respectively. Thereby, each forming groove 34 has, in the circumferential direction, the maximum part 40 and the minimum part 42 of its empty (=inner method) flow cross-section for the lubricant used to lubricate the contact area between the seal section 24 and the seal surface 26, respectively, alternately.

[0046] Each maximum part 40 of the flow cross-section of the forming groove 34 may be at least 3 times, in particular at least 4 times, the minimum part 42 of the flow cross-section S.

[0047] The second side surface 38 on the low-pressure side is curved concave on both sides from each maximum part 40 with respect to the first side surface 36 and extends in the direction of the minimum part 42 located closest in the axial direction. The second side surface 38 (on the low-pressure side) is here configured to be wavy as a whole in the circumferential direction.

[0048] The maximum part 40 and the minimum part 42 of the flow cross-section S of two forming grooves 34 that are directly continuous in the axial direction are arranged offset from each other in the circumferential direction. In this case, each constriction 42 of one forming groove 34 is aligned or substantially aligned with the maximum part 40 of the forming groove 34 arranged closest in the direction toward the medium side or the high-pressure side H in the axial direction. Correspondingly, each maximum part 40 of the flow cross-section S of one forming groove 34 is arranged to be aligned or substantially aligned with the minimum part 42 of the forming groove 34 arranged closest in the axial direction toward the medium side or the high-pressure side H. Thereby, in the axial direction toward the medium side or the high-pressure side H, the maximum part 40 of the forming groove 34 is adjacent to each wide sliding surface segment 32a, and the constriction 42 of the forming groove 34 is adjacent to the narrow sliding surface segment 32b of the sliding surface 32 of the seal section 24, respectively.

[0049] It should be noted that in this way, a sliding surface section of uniform or substantially uniform size is ensured over the entire circumference of the shaft seal ring 18 for dynamically sealing the seal section against the seal surface or the opposing sliding surface of the shaft 12 of the shaft assembly 10 or the machine member 14 in each local cross-section of the seal section. This is advantageous for the sealing performance of the shaft seal ring 18.

[0050] When the shaft 12 and the machine member 14 move relative to each other about the axis of rotation L, this promotes the return action of the shaft seal ring 18 with respect to the lubricating medium that travels towards the low-pressure side N or reaches between the seal section 24 and the seal surface 26. The lubricating medium is derived based on the relative rotational movement between the shaft 12 and the machine member 14 and independently of the direction of rotation, and is pressed along the circumferential direction along the forming groove 34 in the direction of the minimum portion 42 of the flow cross-section S of each forming groove 34. While flowing against the second side surface 38 that is bent / curved and extends axially inward or in the direction of the medium side H, the lubricating medium is accelerated / pumped axially in the direction of the high-pressure region H with respect to the seal surface and by the arrow A, and thus reaches the region of the maximum portion 40 of its flow cross-section S within the forming groove 34 that is closest to the medium side. This promotes the return pumping function of the shaft seal ring 18 axially in the direction of the medium side or the high-pressure side H. It should be noted that the shaft seal ring 18 enables a return function for the lubricating medium arranged in the forming groove 34 independently of the direction of rotation based on the formation of the forming groove 34.

[0051] The shaft seal ring 18 or the seal lip 22 of the shaft seal ring 18 may particularly contain an elastomeric material that is deformable in a rubber-elastic or viscoelastic manner, such as PTFE (polytetrafluoroethylene), or may be formed from this elastomeric material.

[0052] Figure 3 shows another embodiment of the radial shaft seal ring 18. The forming groove 34 is configured to extend annularly and continuously around the entire circumference in the seal section 24 also in this embodiment, and has no interruption. The second side surface 38 of the forming groove 34 does not have a wavy shape, unlike the embodiment shown in FIG. 2. Rather, the second side surface 38 extends linearly from each maximum portion 40 of the flow cross section of the forming groove 34 to the two minimum portions 42 disposed closest to each of the flow cross sections S of the respective forming grooves 34 on both sides. In the regions of each minimum portion 42 and each maximum portion 40, the second side surface 38 forms obtuse angles α1, α2, respectively.

[0053] The second side surface 38 of the forming groove 34 may be shaped to extend curvedly from each maximum portion 40 of the flow cross section of the respective forming groove 34 to the two minimum portions 42 located closest to the flow cross section of the forming groove 34.

[0054] In the embodiment shown in FIG. 4, the second side surface 38 has a concave shape with respect to the first side surface 36, respectively, and according to the embodiment shown in FIG. 5, it has a convex shape with respect to the first side surface 36 of the forming groove 34. The second side surface 38 is configured to extend arcuately in the region of the minimum portion 42 of the flow cross section of each forming groove 34. Due to the curved shape, an enhanced acceleration of the lubricating medium in the direction of each minimum portion / media side H can be achieved during operation, depending on the rotational direction of the shaft 12 and the machine member 14 (FIG. 1). Thereby, the return performance of the shaft seal ring 18 can be further enhanced if necessary.

[0055] Figure 6 shows a detailed breakdown of another embodiment of the shaft seal ring 18. In this embodiment, the forming grooves 34 are each completely interrupted or segmented in the circumferential direction of the shaft seal ring 18. Here too, the second side surfaces 38 each extend from each maximum portion 40 of the flow cross-section of the respective forming groove 34 on both sides to the minimum portion 42 closest to the flow cross-section. The flow cross-section is zero at each minimum portion 42. The minimum portion 42 of the forming groove 34 is substantially aligned axially in the direction of the medium side with the maximum portion 40 of the flow cross-section of the forming groove 34 closest thereto with respect to the seal axis D (Figure 1). The second side surfaces 38 of the forming grooves 34 may extend linearly or convexly curved with respect to the two minimum portions 42 closest to the flow cross-section S of the respective forming groove 34 in a form corresponding to Figure 3.

[0056] It should be noted that the forming grooves 34 of the shaft seal ring 18 may have various geometric shapes of its flow cross-section S, and this will be referred to in detail below with reference to Figure 7.

[0057] The forming grooves 34 may extend obliquely or inclined with respect to the central axis Z instead of extending in a plane perpendicular to the central axis Z as shown in Figures 2 to 6.

[0058] Figure 7A shows a detailed portion of the forming groove 34 formed in a square shape in the seal section 22 of the shaft seal ring 18. The first side surface 36 and the second side surface 38 are configured to extend parallel to each other and are arranged to extend orthogonally with respect to the seal axis D in the installed state of the shaft seal ring 18. The forming groove 34 has a bottom segment 44, and the bottom segment 44 is arranged to extend parallel to the seal axis D. The depth of the forming groove 34 is indicated by the reference numeral T. The width of the forming groove is indicated by the reference numeral B.

[0059] According to FIGS. 7B and 7C, the forming groove 34 may taper in the depth extension direction. Further, both side surfaces 36, 38 may form different angles β, γ with the sliding surface 32 of the seal section 24. According to FIG. 7B, the angle γ of the second side surface 38 is smaller than the angle β of the first side surface 36. According to FIG. 7C, the angle γ is larger than the angle β.

[0060] As shown in FIG. 7D, another polygonal, for example, pentagonal cross-sectional geometry of the forming groove 34 is also possible. Further, one side surface 36, 38 or both side surfaces 36, 38 of the forming groove 34 according to Example 7D may be segmented, that is, may be configured to be bent as shown in the second side surface 38.

[0061] The bottom segment 44 of the forming groove 34 may be arranged to extend obliquely with respect to the sliding surface 32, for example, according to FIGS. 7D and 7E.

[0062] According to FIG. 7F, the forming groove 34 may have a triangular cross-sectional geometry. In this case, the bottom segment 44 that can be defined by the side surfaces 36, 38 is omitted.

[0063] According to FIG. 7G, one side surface 36, 38 or both side surfaces 36, 38 may be configured to be curved at least in a predetermined section, and if necessary, a chamfer 46 can be formed together with the sliding surface. The chamfer 46 promotes the entry of the lubricant into the forming groove 34. The bottom segment 44 may be configured to be curved as shown in FIG. 7H and can transition smoothly to one of the two side surfaces 36, 38.

[0064] According to FIG. 7I, the forming groove 34 may generally have a rounded symmetric geometry of its flow cross-section, or according to FIG. 7J, may have a rounded asymmetric cross-sectional geometry.

[0065] As shown in the embodiment shown in FIG. 7C in FIG. 8A, the groove depth T of the bottom segment 44 may periodically change by a predetermined value Δ when viewed in the circumferential direction of the forming groove 34. Since the angle β of the groove side surface 36 on the high-pressure side is gentler than the angle γ of the groove side surface 38 on the low-pressure side, the periodic change Δ in the groove depth T of the bottom segment 44 brings about a return action in the direction toward the high-pressure side H, particularly when the groove width of the forming groove 34 remains the same in the circumferential direction.

[0066] As shown in the embodiment shown in FIG. 7D in FIG. 8B, the side shape of the groove side surface 39 on the low-pressure side, which is inclined in this embodiment and directed toward the high-pressure side H or the groove side surface 36 on the high-pressure side of the forming groove 34, may periodically change by a predetermined value Δ when viewed in the circumferential direction of the forming groove 34. The periodic change Δ in the side shape of the inclined groove side surface 39 on the low-pressure side brings about a return action in the direction toward the high-pressure side H based on the inclination of the groove side surface 39 on the low-pressure side directed toward the high-pressure side H, particularly when the groove width of the forming groove 34 remains the same in the circumferential direction. Instead of the inclined groove side surface 39 shown in FIG. 8B, another groove side surface 38 on the low-pressure side directed toward the high-pressure side H or the groove side surface 36 on the high-pressure side, such as the rounded groove side surface 38 on the low-pressure side in FIGS. 7H to 7J, may also have a side shape that periodically changes by the value of Δ when viewed in the circumferential direction of the forming groove 34.

[0067] Instead of being straight as shown in FIGS. 2 to 6, the first side surface 36 on the high-pressure side of the forming groove 34 may be modulated in the axial direction when viewed in the circumferential direction of the forming groove 34. Thus, in FIG. 9, the first side surface 36 is configured in a wave shape or a sine wave shape, and moreover, it is configured periodically and with the same amplitude in the circumferential direction of the forming groove 34. Instead of a sine wave, the axial amplitude of the first side surface 36 may change arbitrarily differently. Thus, for example, there may be a small "overshoot" in amplitude that intentionally causes forced swirling in the forming groove 34. The maximum amplitude of the first side surface 36 is smaller than half of the maximum amplitude of the second side surface 38, and preferably smaller than 1 / 4 of the maximum amplitude of the second side surface 38.

[0068] Figures 10A through 10H show various variations of the first side surface 36 and / or the second side surface 38, with the amplitude plotted over the circumferential angle φ of the shaft 12. The variations are various functions that are n periods with respect to the circumference of the shaft 12, where n is a natural number.

[0069] Figure 10A shows a sinusoidal shape having a 1 / 2 period length (n = 2).

[0070] Figure 10B shows a sinusoidal shape having a 1 / 5 period length (n = 5).

[0071] Figure 10C shows an aperiodic shape formed by the sum of the shapes shown in FIGS. 10A and 10B.

[0072] Figure 10D shows an aperiodic shape formed by the difference between the shapes shown in FIGS. 10A and 10B.

[0073] Figure 10E shows a periodic triangular shape (n = 6).

[0074] Figure 10F shows a periodic sawtooth shape (n = 6).

[0075] Figure 10G shows a periodic symmetric arc shape (n = 3).

[0076] Figure 10H shows a periodic asymmetric arc profile (n = 4).

[0077] In a particularly preferred embodiment of the forming groove 34, side surfaces 36, 38 having the same period or a period of one of the side surfaces 36, 38 that is four times the period of the other side surface 36, 38 are combined. Preferably, over the entire circumference of the forming groove 34, as many as possible of the minimum portions 42 of the flow cross-section of the forming groove 34 are arranged to coincide with as many as possible of the maximum portions 40 of the forming groove 34 that are located closest thereto each time.

[0078] Unlike FIGS. 2 to 6 where the maximum part 40 and the minimum part 42 of the flow cross-section of two adjacent forming grooves 34 are arranged to be axially aligned, the minimum part 42 of the flow cross-section of one forming groove 34 may be circumferentially displaced with respect to the maximum part 40 closest to it in the flow cross-section of the closest forming groove 34, and moreover, starting from the aligned arrangement, it may be displaced by up to half the angular interval between the minimum part of the forming groove 34 and the adjacent maximum part. This displacement makes it possible to affect the characteristics of the return action. Particularly preferably, the displacement is about 1 / 4 of the angular interval between the minimum part and the adjacent maximum part of one forming groove 34. The aligned arrangement of the minimum part 42 of the flow cross-section of one forming groove 34 with respect to the maximum part 40 closest to it in the closest forming groove 34 corresponds to an angular displacement δ of 0°. In FIG. 11, the minimum part 42 of the flow cross-section of one forming groove 34 has an angular displacement δφ of 90° with respect to the maximum part 40 closest to it in the flow cross-section of the closest forming groove 34, which corresponds to half the angular interval between the minimum part 42 and the adjacent maximum part 40 of the forming groove 34.

[0079] The embodiments shown in FIGS. 12A and 12B differ from FIGS. 2 to 6 in the following points. That is, in this embodiment, the forming grooves 34 extend straight and parallel (FIG. 12A) or in a wave shape and parallel (FIG. 12B) adjacent to each other. The groove depth of the forming groove 34 has, when viewed in the circumferential direction of this forming groove 34, periodically and alternately a valley part, that is, the maximum part 40 of the flow cross-section of the forming groove 34, and a peak part, that is, the minimum part 42 of the flow cross-section of the forming groove 34. Such a periodic or aperiodic change in the groove depth T results in a return action in the direction towards the high-pressure side H, based on the flatter groove side surface on the high-pressure side (as in FIG. 8A) and / or based on the inclination of the groove side surface on the low-pressure side towards the high-pressure side (as in FIG. 8B), especially when the groove width of the forming groove 34 remains the same in the circumferential direction.

Claims

1. A shaft seal ring (18) for sealing the medium side H with respect to the outside N of the shaft assembly (10), having a sealing section (24) having a sliding surface (32) for dynamically sealing against a sealing surface (26) of a mechanical member (14) of the shaft assembly (10) extending along a sealing axis (D) in an operating state, wherein the sealing section (24) is provided with a plurality of forming grooves (34), the forming grooves (24) being spaced apart from each other in the direction of the sealing axis and each being open towards the sliding surface (32), each forming groove (34) being laterally defined by a first side surface (36) arranged on the medium side and a second side surface (38) arranged on the ambient side during operation of the shaft seal ring (18), the first side surface (36) having a straight or substantially straight shape in the circumferential direction, the second side surface extending in a bidirectional manner in the circumferential direction of the shaft seal ring (18) from each maximum of the flow cross-section (S) of the forming groove (34) in the axial direction towards the first side surface (36), to the minimum (42) of the flow cross-section (S), each minimum (42) of one forming groove (34) being arranged to coincide or substantially coincide with the maximum (40) of the forming groove (34) located closest thereto, or the groove depth (T) of the forming groove (34) or the side shape of the groove side surface (39) of the forming groove (34) varies in the circumferential direction of the forming groove (34), whereby the maximum (40) and minimum (42) of the flow cross-section (S) can be alternately formed within the forming groove (34), each minimum (42) of one forming groove (34) being arranged to coincide or substantially coincide with the maximum (40) of the forming groove (34) located closest thereto, a shaft seal ring (18).

2. The shaft seal ring (18) according to claim 1, characterized in that at least a part of the forming grooves (34) or each forming groove (34) is configured to be closed in a ring shape.

3. The shaft seal ring (18) according to claim 1, characterized in that at least a part of the forming grooves (34) is completely interrupted in the circumferential direction.

4. The shaft seal ring (18) according to claim 1 or 2, characterized in that the maximum part (40) of the flow cross-section (S) is at least twice, preferably at least three times, and very particularly preferably at least four times the size of the minimum part (42) of the flow cross-section (S).

5. The shaft seal ring (18) according to any one of claims 1 to 4, characterized in that the second side surface (38) extends straight in the circumferential direction, or convexly curved, or concavely curved on both sides of each maximum part (40) of the flow cross-section (S) of each forming groove (34) or a part of the forming groove (34), in the direction towards the first side surface (36) in the axial direction, towards each minimum part (42).

6. The shaft seal ring (18) according to any one of claims 1 to 5, characterized in that at least a part of the forming groove (34) or each forming groove (34) has a rounded geometric shape or a polygonal geometric shape of its flow cross-section (S).

7. The shaft seal ring (18) according to any one of claims 1 to 6, characterized in that the first side surface (36) and / or the second side surface (38) have different side surface gradients (β, γ) from each other at least in a predetermined section with respect to the seal axis (D) of the shaft seal ring (18).

8. The shaft seal ring (18) according to any one of claims 1 to 7, characterized in that the side surface (36) on the medium side and the side surface (38) on the peripheral side of at least a part of the forming groove (34) or all of the forming grooves (34) converge in the direction towards the seal axis (D) in the radial direction.

9. The shaft seal ring (18) according to any one of claims 1 to 8, characterized in that at least a part of the forming groove (34) or all of the forming grooves (34) have a radial depth T, and the depth T changes in the circumferential direction of the shaft seal ring (18), and in particular at each maximum part (40) of the flow cross-section (S), it is larger than the depth at the minimum part (42) of the flow cross-section (S) of each forming groove (34).

10. A sliding surface segment (32b) disposed between the maximum part (40) of one forming groove (34) and the minimum part (42) of the nearest forming groove (34) is operable by a medium to be deformable radially and / or axially with respect to the remaining shaft seal ring (18), whereby, during the operation of the shaft seal ring (18), the conveyance of the medium axially back from one forming groove to the nearest forming groove (34) can be simplified. The shaft seal ring (18) according to any one of claims 1 to 9, characterized in that.

11. The shaft seal ring (18) according to any one of claims 1 to 10, characterized in that the seal section (24) is formed by a seal lip (22) of the shaft seal ring (18).

12. The shaft seal ring (18) according to any one of claims 1 to 11, characterized in that the shaft seal ring (18) contains or consists of a polymer material that is deformable viscoelastically or rubber-elasticity at least in a predetermined section.

13. The shaft seal ring (18) according to any one of claims 1 to 12, characterized in that the shaft seal ring (18) is configured as a radial shaft seal ring.

14. The substantially straight shape of the first side surface (36) includes axial modulation in the circumferential direction, and the maximum amplitude of the modulation is smaller than half of the maximum amplitude of the second side surface (38), particularly smaller than 1 / 4 of the maximum amplitude of the second side surface (38). The shaft seal ring (18) according to any one of claims 1 to 13, characterized in that.

15. The substantially aligned arrangement of the minimum part (42) of one forming groove (34) with respect to the maximum part (40) of the nearest forming groove (34) includes a circumferential misalignment of at most half of the angular interval between the minimum part of one forming groove (34) and the adjacent maximum part. The shaft seal ring (18) according to any one of claims 1 to 14, characterized in that.

16. For the case where the groove depth (T) of the forming groove (34) or the side surface shape of the groove side surface (39) of the forming groove (34) changes periodically in the circumferential direction of the forming groove (34), whereby the maximum part (40) and the minimum part (42) of the flow cross-section can be alternately formed in the forming groove (34), the forming groove (34) is straight and extends side by side in parallel, or extends in a wavy shape and side by side in parallel. The shaft seal ring (18) according to any one of claims 1 to 15.

17. A shaft assembly (10) having a first mechanical member in the form of a shaft (12) and a second mechanical member (14) surrounding the shaft (12), which are arranged spaced apart from each other while forming a seal gap (16) and are adjustable relative to each other about a rotational axis (L), and a shaft seal ring (18) for sealing the medium side H of the seal gap (16) with respect to the outside N of the seal gap (16). The shaft seal ring (18) according to any one of claims 1 to 16 is formed, and the seal section (24) of the shaft seal ring (18) is applied to the seal surface (26) of the second mechanical member (14) so as to dynamically seal. Shaft assembly (10).

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