Shaft seal rings and shaft assemblies for high rotational speeds

Abstract

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

Description

[Technical field]

[0001] The present invention relates to The method according to claim 1 This invention relates to shaft seal rings and shaft assemblies for high rotational speeds. Such a shaft sealing ring is known, for example, from DE 70 16 392 C1. [Background technology]

[0002] In practice, shaft assemblies are often used for drives in vehicles and for drives of power tools, machine tools, etc. To seal the sealing gap (= bearing gap) between machine parts that can move relative to one another, one or more shaft sealing rings are usually used. The respective maximum permissible rotational speed of the machine parts to be sealed against one another by the shaft sealing rings often depends, inter alia, on the material of the shaft sealing ring, the operating pressure to be sealed against and the type and degree of lubrication of the dynamic sealing sections of the shaft sealing ring. In this case, as is known, shaft sealing rings made of FKM (= fluoro rubber) can in principle be used at higher rotational speeds than shaft sealing rings made of NBR (nitrile butadiene rubber), for example.

[0003] In practice, it is attempted to optimize the lubrication in the region of the contact zone of the dynamic sealing section of the shaft sealing ring with the sealing surface or the counter-sliding surface for the smallest possible thermal and mechanical loads of the shaft sealing ring. The approach pursued here is to provide the sealing section of the shaft sealing ring or the structure adjacent to the shaft sealing ring with a tribological micro- or macro-structure. A shaft sealing ring known from German Utility Model DE 7016392 comprises a peripheral sealing lip with a sealing strip running over the entire circumference between an inner surface and a frustoconical outer surface, which are either facing towards the liquid to be sealed during operation of the seal or facing away from it. The frustoconical outer surface is provided with guide surface portions which form the surfaces of ribs or grooves which contact the sealing strip obliquely. At least two of these guide surface portions contact the sealing strip in oppositely directed circumferential directions, each at an angle of less than 20° to the plane of the sealing strip. The guide surface portion has two intersecting, oppositely directed groups of helical ribs, which are formed on the frustoconical outer surface of the seal. The ribs of each group run parallel to one another and the helical angle, i.e. the angle at which the ribs contact the sealing strip, is identical for both groups of ribs and faces away from one another.

[0004] It is known, for example, from US Patent No. 4,118,856 to provide the sealing section with bidirectionally acting tribostructures in the form of intersecting rib- or web-like material projections, but due to their type of construction, such tribostructures often suffer considerable mechanical wear especially during high-speed use, which is detrimental to the service life of the shaft sealing ring.

[0005] A shaping of the sealing section of a shaft sealing ring, which is likewise rather unsuitable for high rotational speeds, is known from US 20070187904 A1. The sealing section here has a plurality of passages with uniform flow cross-sections which run parallel to one another or obliquely to one another and which intersect, i.e. are fluidly connected, and which end in a partially closed state. A shaping of the running surface of the sealing section is known from DE 10109320 A1.

[0006] EP 0 798 498 A discloses a radial shaft sealing ring in which a sealing section for returning a medium has an annular groove. A hydrodynamic return device is provided at the bottom of the groove, which projects radially inwards and is formed by a circumferentially extending wave. The wave has an inner profile which tapers in a wedge-like manner in the direction towards the medium to be sealed. This radial shaft sealing ring can be used in high-speed applications, but the return capacity is rather limited, for example when the pressing pressure of the shaft sealing ring against the correspondingly arranged sealing surface is relatively high.

[0007] DE 101 54 789 A1 discloses another shaft sealing ring with a sealing lip, which has a sealing section for dynamically sealingly applying against a sealing surface of a machine component. The sealing section has a sliding surface with a number of profiled grooves. The profiled grooves are each configured annularly closed in the circumferential direction of the shaft sealing ring and are delimited in the axial direction relative to the central axis of the shaft sealing ring by a first side surface arranged on the low pressure side and a side surface arranged on the high pressure or medium side. The side surface of each profiled groove arranged on the low pressure side is configured corrugated in the circumferential direction, whereas the side surface of each profiled groove on the high pressure side can be configured straight, i.e. circular, or wavy in the circumferential direction. The profiled grooves certainly ensure a reliable return capability of the lubricating medium that has reached the profiled groove during high-speed use. However, even here, the return force of the shaft sealing ring is limited, especially in the case of high operating pressures to be sealed on the inside or medium side of the sealing gap. Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a shaft seal ring and a shaft assembly equipped with a shaft seal ring, which have further improved lubricating properties and return capacity and which allow a further improved service life even at high rotational speeds, i.e. in high-speed use, as well as when the operating pressure to be sealed is relatively high. [Means for solving the problem]

[0009] The problem with respect to the shaft sealing ring is solved by a shaft sealing ring having the features set forth in claim 1. The shaft assembly according to the invention has the features set forth in claim 17. Preferred refinements of the invention are set forth in the dependent claims.

[0010] The shaft seal ring according to the invention allows the inner or medium side, to which an operating pressure can be applied if necessary, to be sealed against the circumferential or outer side of a seal gap of a shaft assembly. The shaft seal ring has a seal section, which has a sliding surface extending along the seal axis of the shaft seal ring in the assembled or operating state of the shaft seal ring and for dynamically sealingly abutting against an opposing sliding surface of a machine member of the shaft assembly. The seal section has a sliding surface with a plurality of tribological macrostructures in the form of molded grooves. The molded grooves are respectively arranged on the seal section spaced apart from one another in the axial direction relative to the seal axis of the shaft seal ring and are configured open towards the dynamic sliding surface (= contact surface) of the seal section. Each molded groove is laterally bounded by a first passage wall or side surface arranged on the medium side in the operating use of the shaft seal ring and by a second passage wall or side surface arranged on the circumferential side (= outer or low pressure side) in the operating use. The first side surface has a straight or substantially straight extension in the circumferential direction. That is, it is configured circularly with respect to the seal axis. The second side surface extends in both directions in the circumferential direction of the shaft seal ring from the respective maximum of the flow cross-section S of the forming groove to the minimum of the flow cross-section in the axial direction towards the first side surface. In other words, the second side surface is configured such that the flow cross-section is circumferentially reduced and expanded in a given section. According to the invention, each minimum of the flow cross-section of one forming groove is arranged so as to axially match or substantially match the maximum of the flow cross-section of the respective nearest forming groove, in particular the respective nearest forming groove on the media side.

[0011] In an alternative embodiment according to the invention, the groove depth of the forming groove or the profile shape of the groove flank on the low-pressure side, which is directed towards the high-pressure side or towards the groove flank on the high-pressure side, varies in particular periodically in the circumferential direction of the forming groove, so that alternating maxima and minima of the flow cross section can be formed in the forming groove. The groove flank on the low-pressure side can run obliquely or rounded, for example.

[0012] The minimum of the flow cross section of the forming groove is aligned in the axial direction with the maximum of the forming groove located closest to the medium side, so that a narrow sliding surface segment can be arranged between these two sections. Correspondingly, a wide sliding surface segment (in the direction of the seal axis) can 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 the medium side. As a result, during the operation of the shaft sealing ring, a very particularly efficient and particularly resistance-free return transport of the lubricant in the axial direction toward the medium side or high pressure side H can be achieved, and thus a particularly effective lubrication and cooling of the sliding surfaces of the sealing sections can be ensured. In other words, the retractability of the shaft sealing ring is further improved. As a result, the shaft sealing ring is particularly suitable for the high-speed applications mentioned at the beginning.

[0013] It should further be noted that in this way, over the entire circumference of the shaft seal ring, each local cross-section of the seal section can be provided with a sliding surface section of uniform or substantially uniform size for dynamically sealingly applying the seal section against the sealing surface or the counter sliding surface of the shaft assembly, which is advantageous both for the static sealing performance of the shaft seal ring and for the dynamic sealing performance of the shaft seal ring, especially in the case of relatively high operating pressures on the medium side of the lubricating medium to be sealed, and also for the life of the shaft seal ring.

[0014] Particularly preferably, the groove is designed to be closed annularly in the circumferential direction of the shaft sealing ring, so that lubrication and cooling of the sliding surfaces can be guaranteed all around, and local mechanical / thermal overloads on the shaft sealing ring can be countered particularly reliably.

[0015] According to a further embodiment of the invention, at least some or all of the grooves can be completely interrupted in the circumferential direction, which allows the effective sliding surface of the shaft seal ring to be further increased, which is particularly advantageous for the sealing performance of the shaft seal ring.

[0016] Very particularly preferably, each maximum of the flow cross section of the forming groove is at least twice as large, preferably at least three times as large, very particularly preferably at least four times as large as each minimum of the flow cross section. This is particularly advantageous for the lubricant storage capacity of the respective forming groove during operational use, and also for the return pumping capacity (=return capacity) of the shaft sealing ring. In the case of forming grooves that are completely interrupted in the circumferential direction, it is self-evident that the minimum of the flow cross section is zero at each end of the forming groove.

[0017] According to a preferred embodiment of the shaft sealing ring, the second flanks of at least some or all of the forming grooves extend helically, i.e. with a constant gradient in the direction towards the first flank, on both sides of the respective maximum of the flow cross section S of the respective forming groove to the respective minimum of the flow cross section of the respective forming groove, insofar as the second flanks are configured straight on both sides of the maximum up to the respective minimum of the respective forming groove in the development.

[0018] According to an alternative embodiment, the second side surface extends on both sides of the respective maximums of the flow cross section of the shaping groove in a convexly or concavely curved manner with respect to the first side surface in a direction towards the first side surface and to the respective minimums of the flow cross section of the shaping groove. In that respect, the second side surface has a variable slope on both sides of the maximums and the respective minimums. Also in the development section, the second side surface is curved.

[0019] According to this embodiment, the flow cross-sectional shape of the forming groove can be designed to suit the flow characteristics of the lubricating medium and the relative rotational speed of the machine parts to be sealed, so that an axial acceleration favorable for the return action / the desired dynamic pressure of the lubricant in the region of the minimum of the forming groove can be achieved.

[0020] Each profiled groove may according to the invention have a rounded or polygonal cross-sectional shape or a mixture of these cross-sectional shapes, which allows the profiled groove to be optimally adapted to the thickness of the sealing section or the sealing lip which forms the sealing section.

[0021] According to another embodiment of the invention, the first side and / or the second side can have different side slopes at least in certain sections relative to the seal axis of the shaft seal ring, whereby local material weakening of the seal section by the profiled groove can be minimized and, in the case of the second side, an even stronger return action of the shaft seal ring can be achieved.

[0022] The first side surface arranged on the medium or high pressure side and the second side surface arranged on the periphery side of at least some or all of the grooves may preferably converge radially towards the seal axis. In other words, the grooves may taper in the direction of their radial depth extension. On the one hand, this allows for a simplified axial return of the lubricant from one groove to the next. On the other hand, this offers manufacturing advantages in the case of radial sealing rings configured as injection molded parts, which, among other things, allows for a simplified demolding of the radial sealing ring and avoidance of rejects. This also allows for a minimal material weakening of the shaft sealing ring in the region of the grooves.

[0023] The profiled grooves can have a radial depth relative to the seal axis which varies in the circumferential direction of the shaft seal ring and is in particular greater at the maximum of the flow cross section than at the minimum of the flow cross section of the respective profiled groove, as a result of which the flow cross section of the profiled groove can be adjusted particularly efficiently, in particular also in shaft seal rings with smaller dimensions.

[0024] According to a refinement of the invention, the axially directed return-conveying capacity of the shaft sealing ring can be further increased in that the sliding surface segments arranged between the minimum of one groove and the maximum of the respective nearest groove can be deformed radially and / or axially relative to the remaining shaft sealing ring under the influence of the medium, thereby minimizing the mechanical flow resistance for the axial transfer of the lubricating medium from one groove to the groove arranged nearest to the medium.

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

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

[0027] The shaft seal ring according to the invention may be configured as a radial shaft seal ring or as a thrust shaft seal ring. In the case of a 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 axis of movement of the machine part to be sealed. In the case of a thrust shaft seal ring, the seal surface / seal axis is arranged to extend perpendicularly to the central axis of the thrust shaft seal ring.

[0028] Preferably, the substantially straight shape according to the invention of the first flank includes an axial modulation in the circumferential direction, the maximum amplitude of which is smaller than half the maximum amplitude of the second flank, in particular smaller than one quarter of the maximum amplitude of the second flank.

[0029] Preferably, the substantially aligned arrangement according to the invention of the minimum of one groove relative to the maximum of the respective nearest groove comprises a circumferential offset of at most half the angular distance between the minimum of one groove and the adjacent maximum, which offset makes it possible to influence the characteristics of the return action. Particularly preferably, the circumferential offset is approximately ¼ of the angular distance between the minimum of one groove and the adjacent maximum.

[0030] In the present invention, in which the groove depth of the forming groove or the side shape of the groove side of the low-pressure side oriented in the direction of the high-pressure side or in the direction of the high-pressure side groove side of the forming groove changes periodically in the circumferential direction of the forming groove, thereby forming alternate maximum and minimum flow cross-sections within the forming groove, the forming grooves may extend straight and parallel to one another or wavy and parallel to one another.

[0031] The shaft assembly according to the invention comprises a first machine element in the form of a shaft and a second machine element surrounding the shaft, which may in particular be a shaft casing, the shaft and the second machine element being spaced apart from each other forming a sealing gap (=bearing gap) and being adjustable with respect to each other about a rotation axis.

[0032] The shaft sealing ring serves to seal the medium / inner or high-pressure side H against the outer or low-pressure side N of the sealing gap or shaft assembly, and is configured in the manner described above and is applied with its sealing section so as to dynamically seal against a sealing surface or counter-sliding surface of one of the two machine members. In the case of an inner-sealing shaft sealing ring, the sealing surface or counter-sliding surface is formed by the shaft, and in the case of an outer-sealing shaft sealing ring, the sealing surface or counter-sliding surface is formed by the machine member arranged to surround the shaft, i.e. to be located radially outward. When the shaft and the machine member move relative to each other about their rotation axis, this promotes a return effect of the shaft sealing ring towards the low-pressure side N or with respect to the lubricant reaching between the sealing section and the sealing surface. The lubricant is guided in the circumferential direction along the forming grooves based on the relative rotational movement of the shaft and the machine part, is pressed into the constriction of the respective forming groove and is conveyed axially in the direction of the medium side H by the low-pressure side of the forming grooves curved towards the inward or medium side, where the lubricant reaches the widening of the flow cross section of the forming groove respectively located closest on the high-pressure side. This facilitates the return pumping function of the shaft sealing ring in the axial direction in the direction towards the inward or medium side. It should be noted that the shaft sealing ring has a return function for the lubricant located / reached in the forming grooves based on the configuration of the forming grooves and independent of the direction of rotation.

[0033] Naturally, the shaft sealing ring can be clamped with its dynamic sealing section, i.e. with its sealing lip, if present, against the sealing surface by means of an elastomerically deformable preload element.

[0034] Furthermore, the shaft seal ring may be arranged in a (mounting) cartridge, which allows the shaft seal ring to be simplified and, optionally, provided together with further sealing elements known per se, and assembled into a holding structure for the machine element or shaft.

[0035] The sealing lip of the shaft seal ring is provided with a formed groove which, with its sliding surface, is dynamically and statically sealed against the sealing surface, i.e. is open towards the sealing surface.

[0036] The present invention will be described in detail below based on the illustrated embodiments. The illustrated and described embodiments are not to be understood as a limiting list, but rather have an exemplary character for the purpose of explaining the present invention. [Brief description of the drawings]

[0037] [Figure 1] FIG. 2 shows a shaft assembly including a shaft, a machine member surrounding the shaft, and a shaft seal ring for sealing a bearing or seal gap formed between the shaft and the machine member. [Diagram 2] FIG. 2 is a detailed view of a seal section of the shaft seal ring shown in FIG. 1, showing a formed groove on the sliding face side. [Diagram 3] FIG. 4 illustrates a detailed portion of another shaft seal ring. [Figure 4] FIG. 4 illustrates a detailed portion of another shaft seal ring. [Diagram 5] FIG. 4 illustrates a detailed portion of another shaft seal ring. [Figure 6] FIG. 4 illustrates a detailed portion of another shaft seal ring. [Figure 7] 7A-7J show formed grooves for shaft seal rings having various geometries of flow cross section. [Figure 8] FIG. 8A shows a formed groove of a shaft seal ring having a varying groove depth, and FIG. 8B shows a formed groove of a shaft seal ring having a varying side shape of the flow cross section. [Figure 9] FIG. 4 illustrates a detailed portion of another shaft seal ring. [Figure 10] 10A to 10H are diagrams showing various modulation variations of the side surface of a formed groove of a shaft seal ring. [Figure 11] FIG. 4 illustrates a detailed portion of another shaft seal ring. [Figure 12] 12A and 12B are detailed views showing an alternative shaft seal ring. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] In Fig. 1 a shaft assembly 10 is shown which can be used in many technical fields, for example in vehicles, machine tools, power tools or drives for pumps and compressors. The shaft assembly 10 comprises a first machine member in the form of a shaft 12 and a second machine member 14 surrounding the shaft 12, which may be configured as a shaft casing, an assembly cartridge or the like. The shaft 12 and the machine member 14 are arranged spaced apart from each other, forming a bearing or sealing gap 16, and are adjustable relative to each other about a rotation axis, referenced L.

[0039] A shaft seal ring, generally designated by reference number 18, serves to seal the inside or medium side (or high pressure side) H of the seal gap 16 against the outside N of the seal gap 16. The shaft seal ring 18 has a retaining section 20, a sealing lip 22 attached to or molded integrally with the retaining section 20, and a sealing section 24 formed by the sealing lip 22. The sealing lip 22 may extend axially away from the retaining section 20 with respect to a 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 rotation axis L of the shaft assembly 10. The shaft seal ring 18, in this embodiment with its sealing section 24, dynamically seals against a counter sliding or sealing surface 26 of the shaft 12. The retaining section 20 is arranged in a retaining groove 28 of the machine member 14. The retaining section 20 of the shaft seal ring 18 may consist of a different material than the sealing lip 22. The material of the retaining section 20 preferably has a greater modulus of elasticity than the material of the sealing lip 22. The retaining section 20 may, for example, comprise or consist of a metal, in particular a viscoelastically deformable plastic, or a composite material. Of course, the shaft sealing ring may also be integrally formed, for example, from a viscoelastic plastic or elastomer.

[0040] The shaft seal ring 18 may be preloaded against the seal face 26 by a resiliently deformable preload element 30, shown in dashed lines in FIG. 1, in the form of, for example, a worm spring or an elastomeric ring.

[0041] The seal section 24 extends along a seal axis D of the shaft seal ring 18 in the assembled state shown. In the shaft seal ring configured as a radial shaft seal ring in this embodiment, the seal axis D coincides with the center axis Z of the shaft seal ring 18. If the shaft seal ring 18 is configured as a thrust shaft seal ring, the seal surface or seal axis D is arranged in the assembled state to extend perpendicular to the center axis Z of the shaft seal ring and perpendicular to the axis of movement L of both machine members 12, 14.

[0042] 1, the sealing section 24 comprises a sliding surface 32 and a number of contoured grooves 34 arranged on this sliding surface 32. The contoured grooves 34 act as tribostructures and, in the assembled state, are arranged spaced apart from one another in the axial direction relative to the seal axis D. It should be noted that each contoured groove 34 is configured radially open towards the dynamic sliding surface 32 of the sealing section 24 and thus towards the sealing surface 26 of the shaft 12 in the assembled state.

[0043] FIG. 2 illustrates a perspective view of a detailed portion of the seal segment 24 of the shaft seal ring 18 shown in FIG.

[0044] The grooves 34 are laterally delimited in the axial direction during operational use of the shaft sealing ring 18 by a first passage wall / side surface 36, which is arranged on the medium or high-pressure side H, i.e. on the high-pressure side, and a second passage wall / side surface 38, which is arranged on the outside N, i.e. on the low-pressure side. The grooves 34 are configured to extend annularly over the entire circumference and close on both sides in the axial direction. In other words, the grooves 34 do not have any fluid-connecting passages or the like to each other.

[0045] The first flank 36 on the high pressure side of each formed groove 34 has a straight or substantially straight shape in the circumferential direction, whereas the flank 38 arranged on the low pressure side of each formed groove 34 has a wavy shape in the circumferential direction of the shaft sealing ring 18. Thereby, each formed groove 34 has alternating maxima 40 and minima 42 of its free (=inside dimension) flow cross section for the lubricant used to lubricate the contact area between the sealing segment 24 and the sealing face 26, respectively, in the circumferential direction.

[0046] Each maximum 40 of the flow cross-section of the shaping groove 34 may be at least three times, in particular at least four times, larger than a minimum 42 of the flow cross-section S.

[0047] The low pressure side second flank 38 extends from each maximum 40 on both sides in a concave curve with respect to the first flank 36 in the axially nearest direction to the minimum 42. The (low pressure side) second flank 38 here has a generally wavy configuration in the circumferential direction.

[0048] The maximums 40 and minimums 42 of the flow cross sections S of two axially directly adjacent forming grooves 34 are respectively offset from one another in the circumferential direction, such that each narrowing 42 of one forming groove 34 is aligned or substantially aligned with the maximum 40 of the respective nearest forming groove 34 in the axial direction toward the medium side or high pressure side H. Correspondingly, each maximum 40 of the flow cross section S of one forming groove 34 is aligned or substantially aligned with the minimum 42 of the respective nearest forming groove 34 in the axial direction toward the medium side or high pressure side H. Thus, in the axial direction toward the medium side or high pressure side H, the maximums 40 of the forming grooves 34 are respectively adjacent to one wide sliding surface segment 32a, and the narrowings 42 of the forming grooves 34 are respectively adjacent to one narrow sliding surface segment 32b of the sliding surface 32 of the sealing section 24.

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

[0050] When the shaft 12 and the machine element 14 move relative to one another about the axis of rotation L, this promotes the return action of the shaft sealing ring 18 with respect to the lubricating medium which reaches towards the low pressure side N or between the sealing section 24 and the sealing surface 26. The lubricating medium is guided on the basis of the relative rotational movement of the shaft 12 and the machine element 14, and independent of the direction of rotation, and is pressed in the circumferential direction along the forming grooves 34 in the direction of the minimum part 42 of the flow cross section S of the respective forming groove 34. While flowing against the second side surface 38 which runs bent / curved axially inwards or towards the medium side H, the lubricating medium is accelerated / pumped against the sealing surface and in the axial direction according to the arrow A towards the high pressure area H, so that it reaches the forming groove 34 which is located nearest to the medium side in the region of the maximum part 40 of its flow cross section S. This promotes the return pumping function of the shaft sealing ring 18 in the axial direction towards the medium side or high pressure side H. It should be noted that the shaft sealing ring 18, due to the shaping of the shaped groove 34, is capable of a return function for the lubricating medium arranged in the shaped groove 34 independently of the direction of rotation.

[0051] The shaft seal ring 18 or the sealing lip 22 of the shaft seal ring 18 may contain or be formed from an elastomeric material, in particular an elastomeric or viscoelastically deformable material, such as PTFE (polytetrafluoroethylene).

[0052] FIG. 3 shows another embodiment of the radial shaft seal ring 18. The groove 34 is also configured in this embodiment to extend annularly around the entire circumference of the sealing section 24 and has no interruptions. The second side surface 38 of the groove 34 does not have a wavy shape, as opposed to the embodiment shown in FIG. 2. Instead, the second side surface 38 extends linearly from each maximum 40 of the flow cross section of the groove 34 to the two nearest minimums 42 of the flow cross section S of the respective groove 34 on both sides. In the region of each minimum 42 and each maximum 40, the second side surface 38 forms an obtuse angle α1, α2, respectively.

[0053] The second side 38 of the forming groove 34 may be shaped to extend in a curved manner from each maximum portion 40 of the flow cross-section of the respective forming groove 34 to the two nearest minimum portions 42 of 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 relative to the respective first side surface 36, and according to the embodiment shown in Fig. 5, it has a convex shape relative to the first side surface 36 of the forming groove 34. The second side surface 38 is configured to extend in an arcuate manner in the region of the minimum 42 of the flow cross section of the respective forming groove 34. Due to the curved shape, in operational use, an enhanced acceleration of the lubricating medium in the direction of the respective minimum / medium side H can be achieved depending on the direction of rotation of the shaft 12 and the machine element 14 (Fig. 1). This allows the return performance of the shaft sealing ring 18 to be further increased, if required.

[0055] FIG. 6 shows a detailed section of another embodiment of the shaft seal ring 18. In this embodiment, the forming grooves 34 are configured in the circumferential direction of the shaft seal ring 18, respectively completely interrupted or segmented. Here too, the second side surface 38 extends from each maximum 40 of the flow cross section of the respective forming groove 34 on both sides to the nearest minimum 42 of the flow cross section. The flow cross section is zero at each minimum 42. The minimum 42 of the forming groove 34 is substantially aligned in the axial direction with respect to the seal axis D (FIG. 1) with the maximum 40 of the flow cross section of the forming groove 34 located nearest in the direction of the media side. The second side surface 38 of the forming groove 34 may extend linearly or convexly curved to the two nearest minimums 42 of the flow cross section S of the respective forming groove 34 in a manner corresponding to FIG. 3.

[0056] It should be noted that the contoured groove 34 of the shaft seal ring 18 may have various geometries of its flow cross section S, as will be discussed in more detail below with reference to FIG.

[0057] The forming groove 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 in FIGS.

[0058] 7A shows a detailed portion of the rectangular groove 34 of the seal section 22 of the shaft seal ring 18. The first side 36 and the second side 38 are arranged to extend parallel to each other and are arranged to extend perpendicular to the seal axis D in the installed state of the shaft seal ring 18. The groove 34 has a bottom segment 44 which is arranged to extend parallel to the seal axis D. The depth of the groove 34 is indicated by the reference character T. The width of the groove is indicated by the reference character B.

[0059] According to Figures 7B and 7C, the profiled groove 34 may be tapered in its depth extension direction. Furthermore, the two side surfaces 36, 38 may form different angles β, γ with the sliding surface 32 of the sealing section 24. According to Figure 7B, the angle γ of the second side surface 38 is smaller than the angle β of the first side surface 36. According to Figure 7C, the angle γ is larger than the angle β.

[0060] As shown in Fig. 7D, other polygonal, for example pentagonal, cross-sectional geometries of the shaped groove 34 are also possible. Furthermore, one or both sides 36, 38 of the shaped groove 34 according to embodiment 7D may be segmented, i.e., curved, as shown in the second side 38.

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

[0062] 7F, the shaped groove 34 may have a triangular cross-sectional geometry, in which case the bottom segment 44, which may be defined by the sides 36, 38, is omitted.

[0063] According to Fig. 7G, one or both side surfaces 36, 38 can be curved at least in certain sections and, if necessary, can form a chamfer 46 together with the sliding surface, which facilitates the ingress of lubricant into the forming groove 34. The bottom segment 44 can be curved as shown in Fig. 7H and can transition steplessly to one of the two side surfaces 36, 38.

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

[0065] 8A, the groove depth T of the bottom segment 44 may vary periodically by a predetermined value Δ in the circumferential direction of the forming groove 34. Since the angle β of the groove side 36 on the high pressure side is more gradual than the angle γ of the groove side 38 on the low pressure side, the periodic variation Δ in the groove depth T of the bottom segment 44 provides a return action in the direction toward the high pressure side H, especially 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 inclined, in this embodiment, low-pressure side groove side 39 of the forming groove 34, which is directed toward the high-pressure side H or the high-pressure side groove side 36, may vary periodically by a predetermined value Δ in the circumferential direction of the forming groove 34. The periodic change Δ of the side shape of the inclined low-pressure side groove side 39 provides a return action in the direction toward the high-pressure side H based on the inclination of the low-pressure side groove side 39 directed toward the high-pressure side H, especially even if the groove width of the forming groove 34 remains the same in the circumferential direction. Instead of the inclined groove side 39 shown in FIG. 8B, another low-pressure side groove side 38 directed toward the high-pressure side H or the high-pressure side groove side 36, such as the rounded low-pressure side groove side 38 of FIG. 7H-FIG. 7J, may also have a side shape that varies periodically by the value Δ in the circumferential direction of the forming groove 34.

[0067] Instead of being straight as shown in Figures 2 to 6, the first flank 36 on the high pressure side of the forming groove 34 may also be modulated in the axial direction, as viewed in the circumferential direction of the forming groove 34. Thus, in Figure 9, the first flank 36 is configured in a wavy or sinusoidal manner, and is configured periodically and with the same amplitude in the circumferential direction of the forming groove 34. Instead of a sinusoid, the axial amplitude of the first flank 36 may vary arbitrarily differently. Thus, for example, there may be small amplitude "overshoots" that result in an intentionally forced vortex in the forming groove 34. The maximum amplitude of the first flank 36 is less than half the maximum amplitude of the second flank 38, preferably less than ¼ the maximum amplitude of the second flank 38.

[0068] 10A-10H show different variations of first side 36 and / or second side 38 plotted in amplitude over circumferential angle φ of shaft 12. The variations are different functions with n periods about the circumference of shaft 12, where n is a natural number.

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

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

[0071] FIG. 10C shows a non-periodic shape formed by the sum of the shapes shown in FIGS. 10A and 10B.

[0072] FIG. 10D shows a non-periodic shape formed by the difference of the shapes shown in FIGS. 10A and 10B.

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

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

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

[0076] FIG. 10H shows a periodic asymmetric arcuate course (n=4).

[0077] Particularly preferred embodiments of the forming groove 34 combine side surfaces 36, 38 with the same period or with one side surface 36, 38 having a period four times that of the other side surface 36, 38. Preferably, over the entire circumference of the forming groove 34, as many minima 42 of the flow cross section of the forming groove 34 as possible are arranged in such a way that they coincide with as many maxima 40 of the respective nearest forming groove 34 as possible.

[0078] 2 to 6, in which the maximum 40 and the minimum 42 of the flow cross-section of two adjacent forming grooves 34 are arranged in axial alignment, the minimum 42 of the flow cross-section of one forming groove 34 may also be arranged in a circumferentially offset manner with respect to the nearest maximum 40 of the flow cross-section of the nearest forming groove 34, and may be arranged at most offset from the aligned arrangement by half the angular distance between the minimum of one forming groove 34 and the adjacent maximum. This offset makes it possible to influence the characteristics of the return action. Particularly preferably, the offset is about ¼ of the angular distance between the minimum of one forming groove 34 and the adjacent maximum. The aligned arrangement of the minimum 42 of the flow cross-section of one forming groove 34 with respect to the nearest maximum 40 of the nearest forming groove 34 corresponds to an angular offset δ of 0°. In FIG. 11 , the minimum 42 of the flow cross-section of one forming groove 34 has an angular offset δφ of 90° with respect to the nearest maximum 40 of the flow cross-section of the nearest forming groove 34, which corresponds to half the angular spacing between the minimum 42 and the adjacent maximum 40 of the forming groove 34.

[0079] The embodiment shown in Figures 12A and 12B differs from Figures 2 to 6 in the following respects: In this embodiment, the forming grooves 34 run straight and parallel (Figure 12A) and wavy and parallel (Figure 12B) next to each other. The groove depth of the forming grooves 34, as viewed in the circumferential direction of the forming grooves 34, periodically alternates between valleys, i.e., maximums 40 of the flow cross section of the forming grooves 34, and peaks, i.e., minimums 42 of the flow cross section of the forming grooves 34. Such a periodic or aperiodic change in the groove depth T - especially when the groove width of the forming grooves 34 remains the same in the circumferential direction - results in a return action in the direction towards the high pressure side H due to the flatter groove flank on the high pressure side (as in Figure 8A) and / or due to the inclination of the groove flank on the low pressure side, directed towards the high pressure side (as in Figure 8B).

Claims

1. A shaft seal ring (18) for sealing a media side (H) against an outside (N) of a shaft assembly (10), comprising a seal section (24) having a sliding surface (32) for dynamically sealingly abutting a seal surface (26) of a machine member (12) of said shaft assembly (10) extending along a seal axis (D) in an operating state, The seal section (24) has a plurality of shaped grooves (34), the shaped grooves (24) being spaced apart from one another in the direction of the seal axis and each opening toward the sliding surface (32); A shaft seal ring (18), wherein each formed groove (34) is laterally bounded by a first side (36) arranged on a media side in operational use of said shaft seal ring (18) and by a second side (38) arranged on an ambient side in operational use, (a) the first side surface (36) has a straight or substantially straight shape in the circumferential direction, the second side surface (38) extends in both circumferential directions of the shaft seal ring (18) from each maximum of the flow cross-section (S) of the forming grooves (34) in a direction axially toward the first side surface (36) to each minimum of the flow cross-section (S), and each minimum of one forming groove (34) is aligned or substantially aligned with the maximum of the forming groove (34) located closest thereto, or (b) the groove depth (T) of the forming groove (34) varies in the circumferential direction of the forming groove (34), thereby forming alternating maximum and minimum portions (40) of the flow cross-section (S) within the forming groove (34), each minimum portion (42) of one forming groove (34) being arranged to match or substantially match the maximum portion (40) of the forming groove (34) located closest thereto; or (c) at least a part of the forming grooves (34) or each forming groove (34) is configured to be closed in an annular shape, the side shape of the groove side surface (39) of the forming groove (34) changes in the circumferential direction of the forming groove (34), thereby allowing maximum portions (40) and minimum portions (42) of the flow cross section (S) to be formed alternately within the forming groove (34), and each minimum portion (42) of one forming groove (34) is arranged so as to match or substantially match the maximum portion (40) of the forming groove (34) located closest thereto. Shaft seal ring (18).

2. 2. The shaft seal ring (18) of claim 1, wherein in variations (a) and (b), at least a portion of the or each formed groove (34) is configured to be annularly closed.

3. The shaft seal ring (18) of claim 1, wherein in said variations (a) and (b), at least a portion of said profiled groove (34) is completely interrupted in the circumferential direction.

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

5. 2. The shaft seal ring (18) according to claim 1, characterized in that the second side surfaces (38) extend circumferentially straight, convexly curved or concavely curved, respectively, on both sides of each maximum (40) of the flow cross-section (S) of each shaped groove (34) or part of the shaped groove (34), in a direction axially towards the first side surface (36), to respective minimum portions (42).

6. 2. The shaft seal ring (18) of claim 1, wherein at least a portion of the or each shaped groove (34) has a rounded or polygonal geometric shape of its flow cross section (S).

7. 2. The shaft seal ring (18) of claim 1, wherein the first side surface (36) and / or the second side surface (38) have side slopes (β, γ) that differ from one another at least in a predetermined section with respect to the seal axis (D) of the shaft seal ring (18).

8. 2. The shaft seal ring (18) of claim 1, wherein the media-side side (36) and the peripheral-side side (38) of at least some or all of the forming grooves (34) converge in a radial direction toward the seal axis (D).

9. 2. The shaft seal ring (18) of claim 1, wherein at least some or all of the forming grooves (34) have a radial depth (T) which varies in the circumferential direction of the shaft seal ring (18) and in particular is greater at each maximum (40) of the flow cross-section (S) than the depth of the respective forming groove (34) at each minimum (42) of the flow cross-section (S).

10. 2. The shaft seal ring (18) according to claim 1, characterized in that the sliding surface segment (32b) arranged between the maximum part (40) of one molding groove (34) and the minimum part (42) of the respective nearest molding groove (34) can be deformed radially and / or axially relative to the remaining shaft seal ring (18) by being manipulated by a medium, thereby simplifying the axial return transport of the medium from one molding groove to the nearest molding groove (34) during the operational use of the shaft seal ring (18).

11. The shaft seal ring (18) of claim 1, wherein the sealing section (24) is formed by a sealing lip (22) of the shaft seal ring (18).

12. 2. The shaft seal ring (18) of claim 1, wherein the shaft seal ring (18) comprises or consists of a viscoelastically or rubber-elastically deformable polymer material at least in a predetermined section.

13. The shaft seal ring (18) of claim 1, characterized in that the shaft seal ring (18) is configured as a radial shaft seal ring.

14. 2. A shaft seal ring (18) according to claim 1, characterized in that the substantially straight shape of the first side (36) includes an axial modulation in the circumferential direction, the maximum amplitude of which is less than half the maximum amplitude of the second side (38), in particular less than one-quarter of the maximum amplitude of the second side (38).

15. 2. The shaft seal ring (18) of claim 1, wherein the substantially aligned positioning of the minimum portion (42) of one molding groove (34) relative to the maximum portion (40) of the respective nearest neighboring molding groove (34) includes a circumferential offset of at most half the angular spacing between the minimum portion of one molding groove (34) and an adjacent maximum portion.

16. 2. The shaft seal ring (18) according to claim 1, characterized in that the forming grooves (34) extend straight and parallel to one another or wavy and parallel to one another, for cases in which the groove depth (T) of the forming grooves (34) or the side profile of the groove side surfaces (39) of the forming grooves (34) varies periodically in the circumferential direction of the forming grooves (34), thereby making it possible to form alternating maximum and minimum portions (40 and 42) of the flow cross section within the forming grooves (34).

17. 1. A shaft assembly (10) having a first machine member in the form of a shaft (12) and a second machine member (14) surrounding said shaft (12), said first machine member (12) and second machine member (14) being arranged spaced apart from each other while forming a seal gap (16) and adjustable relative to each other about a rotation axis (L), and a shaft seal ring (18) for sealing a medium side (H) of said seal gap (16) against an outside (N) of said seal gap (16), said shaft seal ring (18) being formed as claimed in claim 1, wherein a seal section (24) of said shaft seal ring (18) is dynamically and sealingly applied to a seal surface (26) of said second machine member (14).

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