Pre-stressing element made of two different elastomer materials for radially pre-stressing a seal, and associated seal arrangement

Abstract

According to the invention, a pre-stressing element (10) for radially pre-stressing a seal (4) comprises at least one circumferential first elastomer region (11) made of a first elastomer material and at least one circumferential second elastomer region (12) made of another, second elastomer material, wherein one of the first and second elastomer regions (11, 12) radially outwardly surrounds the other elastomer region and wherein the second elastomer material has, at lower temperatures, a higher modulus of elasticity than the first elastomer material, and the first elastomer material has, at higher temperatures, a higher modulus of elasticity than the second elastomer material. Furthermore, the first elastomer material has, at higher temperatures, more compressive stresses than the second elastomer material, and therefore as a result of the more neutral distribution of stress in the second elastomer material the pressure deformation effect is substantially reduced.

Description

[0001] Preload element made of two different elastomer materials for radial

[0002] Preloading of a seal and associated sealing arrangement

[0003] The present invention relates to a preloading element, in particular a preloading ring or preloading sleeve, made of elastic materials, preferably elastomer, for radially preloading a seal, as well as to a sealing arrangement with two machine parts, with a seal for sealing between the two machine parts, and with a preloading element that radially preloads the seal against one of the two machine parts. Such preloading elements made of elastomer material and sealing arrangements with such a preloading element are well known.

[0004] Elastomers typically have a temperature range within which they can be used. The lower temperature limit is defined by the temperature reaction test (TR) and the glass transition temperature (TG), whereas the upper temperature limit is defined by the compression set. Compression set is a measure of how elastomers behave under prolonged, constant compression deformation and subsequent relaxation. As elastomers lose their resilience over time, they lose the ability to return to their original geometry.

[0005] Typical high-temperature materials used in sealing technology exhibit high elasticity and good compression set at high temperatures (T > 50 °C) and low elasticity at low temperatures (T < -20 °C). The following temperature ranges are specified in data sheets for such high-temperature materials:

[0006] NBR (nitrile butadiene rubber) -30 °C to 100

[0007] HNBR (Hydrogenated Nitrile Butadiene Rubber) -25 °C to 140

[0008] AEM (acrylate ethylene polymethylene rubber) -40 °C to 160

[0009] FKM (fluoropolymer rubber) -20 °C to 200

[0010] TPU -50 °C to 130

[0011] TPE -30 °C to 100

[0012] FFKM (perfluorocarbon rubber) 55 °C to 330 °C; and

[0013] VMQ (silicone rubber) -60 °C to 250

[0014] In contrast, typical low-temperature materials, such as those used in sealing technology, exhibit low temperatures (-60 °C <T < 0 °C) eine gute Elastizität und bei hohen Temperaturen (T >50 °C). The following temperature ranges are specified in data sheets for such low-temperature materials: NBR (nitrile butadiene rubber) -54 °C to 80 °C;

[0015] HNBR (Hydrogenated Nitrile Butadiene Rubber) -25 °C to 140 °C;

[0016] EPDM (ethylene propylene diene (monomer) rubber) -50 °C to 120 °C;

[0017] AU (polyurethane rubber) -40 °C to 90 °C; and

[0018] CR (chloroprene rubber) -20 °C to 120 °C.

[0019] A high compression set means that a seal or preload element made of such a low-temperature material often loses its original function after the first or second thermal load, for example in summer, due to the high temperatures (high ambient temperature plus process temperature, e.g. of a hydraulic system or an internal combustion engine). This can potentially lead to failure in the application. In the automotive, truck or bus sector, as well as in the field of mobile machinery, this can lead to a conflict. Materials such as AEM (ACT70), with a glass transition temperature of -31 °C, do not have the necessary elasticity at low temperatures to simultaneously meet both low-temperature requirements (-40 °C) and high-temperature requirements (+140 °C).

[0020] The elastic modulus describes the behavior of a material when subjected to a compressive force. The higher the elastic modulus, the greater the force required to compress the material. The elastic modulus of a material is temperature-dependent.

[0021] The present invention is based on the object of specifying a prestressing element which has the elasticity required for radial prestressing of a seal both at higher and lower temperatures.

[0022] This object is achieved according to the invention in a prestressing element of the type mentioned at the outset by at least one circumferential, first elastomer region made of a first elastomer material and at least one circumferential, second elastomer region made of a different, second elastomer material. It is crucial that one of the first and second elastomer regions radially surrounds the other elastomer region, with the second elastomer material having a higher modulus of elasticity than the first elastomer material at lower temperatures, and the first elastomer material having a higher modulus of elasticity than the second elastomer material at higher temperatures. In other words, the second elastomer material has its maximum modulus of elasticity in a different temperature range than the first elastomer material.

[0023] According to the invention, the low-temperature behavior is improved by combining elastomer materials with temperature-dependent, different rubber-elastic properties. The two elastomer materials preferably exhibit opposing temperature behavior with regard to their elasticity in order to compensate for the weaknesses of the respective elastomer material in the relevant temperature range. The second elastomer region can be used both for sealing and for preloading the seal at low temperatures. At high temperatures, which can lead to compression set in the second elastomer material over time, the first elastomer material will compensate for the compression set of the second elastomer material due to its increased strength. The preload of the first elastomer material relieves the compressive stress in the second elastomer material at high temperatures.At low temperatures, the first elastomer material hardens and provides the still elastic second elastomer material with corresponding radial preload.

[0024] Particularly preferably, the first elastomer material exhibits greater compressive stress at higher temperatures than the second elastomer material. The more neutral stress distribution in the second elastomer region reduces the load and thus significantly reduces the compression set effect.

[0025] At lower temperatures, the second elastomer material preferably has a modulus of elasticity that is at least 1.1 times greater than that of the first elastomer material. At higher temperatures, the second elastomer material, in contrast to the first elastomer material, has a greater compression set, in particular a compression set that is at least 1.1 times greater. The lower temperatures preferably encompass a temperature range between -60°C and -20°C, in particular between -60°C and 0°C. The higher temperatures are preferably greater than 120°C, in particular greater than 50°C.

[0026] The connection between the two elastomer areas can be either form-fitting or material-fitting or a combination of both.

[0027] In a preferred embodiment of the invention, the first and second elastomer regions are two separate parts, wherein one of the two parts can be accommodated in a recess of the other part, for example, in a groove or annular groove. A particularly preferred embodiment is one in which the first elastomer region is arranged radially inward or outward, and the second elastomer region is exposed, at least in sections, preferably completely, radially outward or radially inward, i.e., is not covered by the first elastomer region radially outward or inward.

[0028] In another preferred embodiment, the first and second elastomer regions are connected to one another in a materially bonded manner as an alternative to the positive connection, wherein one of the first and second elastomer regions can be partially or completely embedded in the other elastomer region.

[0029] Preferably, the first elastomer region has at least one sealing zone on its side facing away from the second elastomer region, wherein, for maximum contact force, the sealing zone and the second elastomer region are arranged at least partially at the same axial height with respect to a longitudinal axis of the prestressing element. If the first elastomer region has two axially spaced sealing zones on its side facing away from the second elastomer region, the second elastomer region is arranged axially between the two sealing zones to ensure maximum contact force.

[0030] In one embodiment, the prestressing element according to the invention has at least two second elastomer regions arranged axially spaced apart from one another, which can radially prestress at least one sealing zone of the first elastomer region. If the first elastomer region has two axially spaced sealing zones on its side facing away from the second elastomer region, the two second elastomer regions can be arranged at the axial heights of the sealing zones for maximum contact force.

[0031] Although the first and / or second elastomer regions can, in principle, have any desired cross-section, they preferably have a substantially round, rectangular, particularly square, club-shaped, or X-shaped cross-section. The club-shaped and X-shaped cross-sections each have an inner and / or outer circumferential geometry, for example, a groove or annular groove, into which an elastomer ring can be inserted.

[0032] To enable the preload to be individually tailored by the preload element over the widest possible range, the first elastomer region and / or the second elastomer region can each comprise several circumferential elastomer sections made of different first or second elastomer materials. The materials and dimensions of the individual elastomer sections are selected to achieve the desired temperature-dependent preload behavior.

[0033] Particularly preferably, the first elastomer material comprises or consists of one or more of the following high-temperature materials: NBR, HNBR, AEM, FKM, FFKM, and VMQ. Particularly preferably, the second elastomer material comprises or consists of one or more of the following low-temperature materials: NBR, HNBR, EPDM, AU, and CR.

[0034] Preferably, the axial width of the outer elastomer region is less than half the axial width of the inner elastomer region and / or the radial thickness of the outer elastomer region is less than half the radial distance between the radial inside of the inner elastomer region and the radial inside of the outer elastomer region. In a further aspect, the invention also relates to a sealing arrangement, in particular a rod or piston sealing arrangement, with a first machine part and with a second machine part, which are translationally or rotationally movable relative to one another, with a seal arranged between the two machine parts in order to seal the two machine parts from one another, and with a prestressing element as described above, which prestresses the seal radially inwardly or outwardly against one of the two machine parts.

[0035] The required elasticity or preload of the preload ring is provided by the second elastomer area at lower temperatures and by the first elastomer area at higher temperatures.

[0036] Preferably, a second elastomer region of the prestressing element facing away from the seal is arranged at the same axial height as a sealing zone of the seal adjacent to the machine part, whereby the sealing zone and the second elastomer region lie on the same (radial) line of action.

[0037] Further advantages and advantageous embodiments of the subject matter of the invention can be found in the description, the drawings, and the claims. Likewise, the features mentioned above and those listed below can be used individually or in combination in any desired manner. The embodiments shown and described are not to be understood as an exhaustive list, but merely as examples for describing the invention.

[0038] They show:

[0039] Figs. 1a-1d show cross sections of various prestressing rings according to the invention with a round, inner elastomer region and an outer elastomer region whose width is less than half the width of the inner elastomer region, for four different cross sections of the outer elastomer region in each case; Figs. 2a-2d show cross sections of various prestressing rings according to the invention with a square, inner elastomer region and with an outer elastomer region whose width is less than half the width of the inner elastomer region, for four different cross sections of the outer elastomer region in each case;

[0040] Figs. 3a-3d show cross sections of various prestressing devices according to the invention with a club-shaped inner elastomer region and with an outer elastomer region whose width is less than half the width of the inner elastomer region, for four different cross sections of the outer elastomer region;

[0041] Figs. 4a-4d show cross sections of various prestressing devices according to the invention with an X-shaped inner elastomer region and with an outer elastomer region whose width is less than half the width of the inner elastomer region, for four different cross sections of the outer elastomer region;

[0042] Figs. 5a-5d show cross sections of various prestressing devices according to the invention with a round, inner elastomer region and with an outer elastomer region whose width is greater than half the width of the inner elastomer region, for different cross sections of the outer elastomer region;

[0043] Figs. 6a-6d show cross sections of various prestressing devices according to the invention with an X-shaped inner elastomer region and with two axially spaced, identical outer elastomer regions, the width of which is each less than half the width of the inner elastomer region, for four different cross sections of the outer elastomer regions;

[0044] Figs. 7a-7d show cross sections of various prestressing elements according to the invention with a club-shaped, inner elastomer region and with two axially spaced, identical outer elastomer regions, each of which has a width less than half the width of the inner elastomer region, for four different cross sections of the outer elastomer regions; Figs. 8a-8d show cross sections of various prestressing elements according to the invention with a round, first elastomer region and with four identical second elastomer regions, each of which has a width less than half the width of the inner elastomer region, for four different cross sections of the second elastomer regions;

[0045] Figs. 9a-9c Cross sections of two prestressing rings according to the invention with a round, inner elastomer region and with different outer elastomer regions (Figs. 9a, 9b) as well as the corresponding pressure distribution of the two prestressing rings (Fig.

[0046] 9c);

[0047] Figs. 10a-10d show a rod sealing arrangement with a seal and with a conventional preload ring (Fig. 10a) and with a preload ring according to the invention (Figs. 10b-10d) for preloading the seal radially inward;

[0048] Figs. 11a-11d show a piston seal arrangement with a seal and with a conventional preload (Fig. 11a) and with a preload according to the invention (Figs. 11b-11d) for preloading the seal radially outwards;

[0049] Figs. 12a-12c show a piston seal arrangement with a seal and with a modified preload according to the invention for preloading the seal radially outward; and

[0050] Figs. 13a-13d show a rotary seal arrangement with two axially spaced seals and with a preloading sleeve according to the invention with a sleeve-shaped, inner elastomer region and with two axially spaced, identical outer elastomer regions for preloading the two seals radially inward, for each of four different cross sections of the second elastomer regions.

[0051] Figs. 1a-1d show various preloading elements, here preloading rings 10, for radially preloading a seal 4 (Figs. 10-13), with a circumferential first, here inner, elastomer region 11 made of a first elastomer material and with a circumferential second, here outer, elastomer region 12 made of a different, second elastomer material. The outer elastomer region 12 surrounds the inner elastomer region 11 and has an axial width that is less than half the axial width of the inner elastomer region 11. The inner elastomer region 11 has a circumferential inner sealing zone 13. The outer elastomer region 12 is arranged at the same axial height as the inner sealing zone 13 with respect to a longitudinal or central axis 14 of the preload ring 10, so that the inner sealing zone 13 and the outer elastomer region 12 lie on the same (radial) line of action.

[0052] The prestressing element 3 has a round cross-section in Fig. 1 a, a square cross-section in Fig. 1 b, a club-shaped cross-section in Fig. 1 c and an X-shaped cross-section in Fig. 1 d.

[0053] In the temperature range between -60 °C and 120 °C, the second elastomer material exhibits a higher modulus of elasticity (compression modulus / compression modulus) than the first elastomer material at lower temperatures (-60 °C < T < -20 °C, in particular -60 °C < T < 0 °C). The first elastomer material exhibits a higher modulus of elasticity (compression modulus / compression modulus) than the second elastomer material at higher temperatures (50 °C < T < 120 °C). In particular, the second elastomer material can exhibit its maximum modulus of elasticity in a different temperature range than the first elastomer material.

[0054] In other words, the first elastomer material of the inner elastomer region 11 is a high-temperature material that exhibits higher elasticity and a higher compression set at high temperatures (50 °C < T < 120 °C) and lower elasticity and a lower compression set at low temperatures (-60 °C < T < -20 °C). The second elastomer material of the outer elastomer region 12, on the other hand, is a low-temperature material that exhibits higher elasticity and a higher compression set at low temperatures (-60 °C < T < -20 °C) and lower elasticity and a lower compression set at high temperatures (50 °C < T < 120 °C).

[0055] Preferably, the second elastomer material has a modulus of elasticity that is at least twice as large as that of the first elastomer material at lower temperatures, preferably between -60 °C and 0 °C, and a compression set that is at least twice as large as that of the first elastomer material at temperatures higher than 120 °C, preferably at temperatures higher than 50 °C.

[0056] The first elastomer material, for example, comprises or consists of one or more of the following materials: NBR, HNBR, AEM, FKM, FFKM, and VMQ. The second elastomer material, for example, comprises or consists of one or more of the following materials: NBR-N7T40, HNBR, EPDM, AU, and CR.

[0057] The first and second elastomer regions 11, 12 can, for example, be separate, form-fitting parts, in which case the outer elastomer region 11 can be accommodated in a radially outwardly open geometry, for example a groove 15 (Figs. 3a-3d) or annular groove 16 (Figs. 9a, 9b), of the inner elastomer region 11. Alternatively, the first and second elastomer regions 11, 12 can also be integrally connected to one another to form a single part, in which case the outer elastomer region 12 can be partially or completely embedded in the inner elastomer region 11.

[0058] The required elasticity or preload of the preload ring 10 is provided by the second elastomer region 12 at lower temperatures and by the first elastomer region 11 at higher temperatures.

[0059] The preload rings 10 shown in Figs. 2a-2d differ from the preloads 10 of Figs. 1 a-1 d only in that the inner elastomer region 11 has a square cross-section.

[0060] The preload rings 10 shown in Figs. 3a-3d differ from the preload rings 10 in Figs. 1a-1d only in that here the inner elastomer region 11 has a club-shaped cross-section with two circumferential, axially spaced, inner sealing zones 13. The outer elastomer region 12 is arranged axially centrally between the two sealing zones 13. The preload rings 10 shown in Figs. 4a-4d differ from the preload rings 10 in Figs. 3a-3d only in that here the inner elastomer region 11 has an X-shaped cross-section. Here too, the outer elastomer region 12 is arranged axially centrally between the two sealing zones 13.

[0061] The preload rings 10 shown in Figs. 5a-5d differ from the preloads 10 of Figs. 1 a-1 d only in that here the axial width of the outer elastomer region 12 is significantly larger than half the axial width of the inner elastomer region 11.

[0062] Figs. 6a-6d show various preload rings 10 with an X-shaped, inner elastomer region 11 made of the first elastomer material and two axially spaced, outer elastomer regions 12 made of the second elastomer material. The axial width of the outer elastomer regions 12 is significantly smaller than half the axial width of the inner elastomer region 11. The two outer elastomer regions 12 are each arranged at the axial heights of the two circumferential, axially spaced, inner sealing zones 13 of the inner elastomer region 11, so that the inner sealing zones 13 and the outer elastomer regions 12 each lie on the same (radial) lines of action. The two outer elastomer regions 12 have the same round cross-section in Fig. 6a, the same square cross-section in Fig. 6b, the same club-shaped cross-section in Fig. 6c, and the same X-shaped cross-section in Fig. 6d.

[0063] The preload rings 10 shown in Figs. 7a-7d differ from the preload rings 10 of Figs. 6a-6d only in that the inner elastomer region 11 has a club-shaped cross-section.

[0064] The preload rings 10 shown in Figs. 8a-8d differ from the preload rings 10 of Figs. 1a-1d only in that here, three additional second elastomer regions 12a, 12b, 12c made of the second elastomer material are arranged equidistantly on the outer circumference of the first elastomer region 11, namely two second elastomer regions 12a, 12b on both sides and a further second elastomer region 12c on the inside of the first elastomer region 11. In this case, the inner sealing zone 13 is formed by the inner second elastomer region 12c. The second elastomer regions 12, 12a-12c have a round cross-section in Fig. 8a, a square cross-section in Fig. 8b, a club-shaped cross-section in Fig. 8c, and an X-shaped cross-section in Fig. 8d.

[0065] Figs. 9a, 9b show two different preload rings 10 with the same round, inner elastomer region 11, in the annular groove 16 of which an elastomer ring 17, 17' forming the outer elastomer region 12 is arranged with the same cross-sectional radius, namely a round elastomer ring 17 in Fig. 9a and a round elastomer ring 17' with a flattened outer side in Fig. 9b. As the associated pressure distribution of the two preload rings 10 shown in Fig. 9c illustrates, by varying the cross-sectional geometry of the elastomer ring 17, 17' or the outer elastomer region 12, the pressure P acting on the sealing zone 13 in the installed state can be varied and adjusted over the axial width b of the preload ring 10. Thus, the round elastomer ring 17 shown in Fig. 9a has a significantly higher pressure in the central region than the flattened elastomer ring 17' shown in Fig. 9b.

[0066] In the preload rings 10 of Figs. 1-9, the first elastomer region 11 is arranged on the inside and the second elastomer region(s) 12 are arranged on the outside to preload the sealing ring 2 radially inward. In embodiments shown further below in Figs. 11 and 12—exactly the opposite of Figs. 1-9—the first elastomer region 11 can be arranged on the outside and the second elastomer region(s) 12 can be arranged on the inside to preload the sealing ring 2 radially outward. Such embodiments are referred to below as reversed embodiments.

[0067] In the preload rings 10 of Figs. 1-9, the axial width bA of the outer elastomer region 12 is preferably smaller than half the axial width BA of the inner elastomer region 11 and / or the radial thickness dR of the outer elastomer region 12 is smaller than half the radial distance AR between the radial inner side 11a of the inner elastomer region 11 and the radial inner side 12a of the outer elastomer region 12, as shown merely by way of example in Fig. 1a. Figs. 10a-10d show a rod sealing arrangement 1 that is predominantly used in cylinders and serves to seal fluids. It prevents hydraulic fluid from escaping from the cylinder chamber and is mounted in the closure piece of the cylinder.The rod seal assembly 1 comprises a first (inner) machine part 2, here exemplary in the form of a rod or shaft, a second (outer) machine part 3, which are translationally or rotationally movable relative to one another, an annular primary seal 4, and a conventional preload ring 110 (Fig. 10a) or a preload ring 10 designed as above (Figs. 10b-10d) for preloading the primary seal 4 radially inward. The primary seal 4 and the preload ring 10, 110 surrounding the primary seal 4 on the outside are arranged in an inwardly open annular groove 5 of the second machine part 3. The preload ring 10 presses the primary seal 4 radially inward and thus into contact with the shaft 2.In other words, the primary seal 4 serves for dynamic sealing with the shaft 2 and the preload ring 10, 110 both for static sealing with the second machine part 3 and with the primary seal 4 and for pressing the primary seal 4 radially inward against the shaft 11.

[0068] The conventional preload ring 110 shown in Fig. 10a is a round preload ring made of a single elastomer material, e.g., a high-temperature material such as NBR, HNBR, AEM, or FKM. The preload ring 10 shown in Fig. 10b is the preload ring shown in Fig. 1a, but any of the other preload rings 10 shown in Figs. 1-9 can be used instead. As shown in Fig. 9c, by varying the cross-sectional geometry of the second elastomer region(s) 12 of the preload ring 10, the radially inward pressure acting on an inner sealing zone (sealing edge) 6 of the primary seal 4 can be varied and adjusted. The required elasticity or preload of the preload ring 10 is provided by the second elastomer region 12 at lower temperatures and by the first elastomer region 11 at higher temperatures.

[0069] In the preload ring 10 shown in Fig. 10c, the inner elastomer area

[0070] 11 has a rectangular cross-section with an outwardly open annular groove 16, the groove depth of which corresponds approximately to the cross-sectional diameter of the elastomer ring 17 inserted therein, forming the outer elastomer region 12. In the preload ring 10 shown in Fig. 10d, the inner elastomer region 11 has an H-shaped cross-section with an outwardly open annular groove 16 and with an additional, inwardly open annular groove 7, in which the primary seal 4 is arranged. The outwardly open annular groove 16 can optionally have an inclined ramp 8 in the corner region between the two groove flanks and the groove base, which has the effect that a temperature-dependent change in the preload force can be adjusted even while stiffening the inner elastomer region 11.

[0071] Figs. 11a-11d show a piston seal arrangement 1', which is predominantly used in hydraulic cylinders as a fluid seal. The installation spaces are within the cylinder and serve to seal the piston against the cylinder barrel. The piston seal arrangement 1' comprises a first (outer) machine part 2, a second (inner) machine part 3, here exemplary in the form of a piston, which are movable relative to one another in a translational or rotational manner, a primary seal 4 and a conventional preload ring 110 (Fig. 11a) or a preload ring 10 designed as above (Figs. 11b-11d) for preloading the primary seal 4 radially outward. The primary seal 4 and the preload ring 10, 110 surrounding the primary seal 4 on the inside are arranged in an outwardly open annular groove 5 of the piston 3.The primary seal 4 serves for dynamic sealing with the first machine part 2 and the preloading element 10, 110 both for static sealing with the piston 3 and for pressing the primary seal 13 radially outwards against the first machine part 2.

[0072] The conventional preload ring 110 shown in Fig. 11a is a round preload ring made of a single elastomer material, e.g., a high-temperature material such as NBR, HNBR, AEM, or FKM. The preload ring 10 shown in Fig. 11b is the reverse of Fig. 1a, with a first, outer, round elastomer region 11 and a second, inner, round elastomer region 12; however, any other preload ring 10 reversed of Figs. 1-9 can also be used instead. Analogous to Fig. 9c, by varying the cross-sectional geometry of the second elastomer region(s) 12 of the preload ring 10, the pressure acting radially outward on the outer sealing zone (sealing surface) 6 of the primary seal 4 can be varied and adjusted. The required elasticity orPreload of the preload ring 10 is provided at lower temperatures by the second elastomer region 12 and at higher temperatures by the first elastomer region 11.

[0073] In the preload ring 10 shown in Fig. 11 c, the second elastomer region 12 has a rectangular cross-section. Instead of being trapezoidal as in Figs. 11 a, 11 d, the primary seal 4 has a rectangular cross-section with chamfered inner corners.

[0074] The piston sealing arrangement T shown in Figs. 12a-12c differs from the piston sealing arrangement T of Fig. 11d only in that here the second elastomer region 12 in Fig. 12a has two circumferentially extending elastomer sections 21, 22 made of different second elastomer materials, and in Figs. 12b, 12c has three circumferentially extending elastomer sections 21, 22, 23 made of different second elastomer materials. In Fig. 12a, the two elastomer sections 21, 22 are formed by two lateral halves, and in Figs. 12b, 12c, an inner elastomer section 23 is additionally embedded centrally in the two elastomer sections 21, 22. By varying the different second elastomer materials of the second elastomer region 12, the radially outwardly acting preload can be varied and adjusted. In addition to the (inner) second elastomer region 12, Fig.12c, an outer second elastomer region 12' made of different second elastomer materials is arranged in the prestressing ring 10.

[0075] It is understood that the second elastomer region shown in Figs. 1-10 can also analogously have several circumferential elastomer sections made of different materials.

[0076] The rotary seal arrangement 1 shown in Figs. 13a-13d comprises a first (inner) machine part 2, here exemplary in the form of a rod or shaft, a second (outer) machine part 3, which are translationally or rotationally movable relative to one another, two axially spaced primary seals 4, each with an externally arranged support body 24, against which the primary seal 4 rests laterally in the axial direction, and a club-shaped preload or sleeve 10 designed as in Fig. 7. The support bodies 24 are each held in an inwardly open annular groove of the preload sleeve 10. The two axially spaced, second (outer) elastomer regions 12 of the preload ring 10 are each arranged at the same axial height as the support bodies 24 in order to preload the primary seals 4 radially inward or to press them into contact with the shaft 3.The preload ring 10 has one or more radial through-bores 25 between the two primary seals 4, which open into an interior space 26 defined by the shaft 2, the primary seals 4, and the inner side of the preload sleeve 10. The required elasticity or preload of the preload ring 10 is provided by the second elastomer region 12 at lower temperatures and by the first elastomer region 11 at higher temperatures.

[0077] The two outer elastomer regions 12 have the same round cross-section in Fig. 13a, the same square cross-section in Fig. 13b, the same club-shaped cross-section in Fig. 13c and the same X-shaped cross-section in Fig. 13d.

[0078] When a pressurized fluid is introduced into the interior space 26 serving as the rotary feedthrough area, the primary seals 4 are pressed against the support bodies 24 in an axial direction proportional to the pressure when a predetermined differential pressure between a high pressure prevailing in the interior space 26 (high pressure area H) and a low pressure prevailing in the low pressure area N is exceeded. The support bodies 24 are displaced axially outwards in the direction of the low pressure side N under elastic deformation of the preload sleeve 10 until the primary seals 4, with their respective sealing edges 27, make sealing contact with the shaft 3 in a radial direction, thereby creating a fluid-tight seal in the high pressure area H. The adjusting movement of the support bodies 24 can, if they are made of a viscous elastic material, be caused at least in part by a section-wise (elastic) deformation of the support bodies 24 in the direction of the low pressure area N.When the pressure drops below the specified differential pressure, the support bodies 24 are moved back in the axial direction into the rest position shown in Fig. 13 by the elastic restoring capacity of the preload sleeve 10.

Claims

Patent claims 1. Prestressing element (10), in particular a prestressing ring or sleeve, made of elastic materials, preferably elastomer, for radially prestressing a seal (4), characterized by at least one circumferential, first elastomer region (11) made of a first elastomer material and at least one circumferential, second elastomer region (12) made of a different, second elastomer material, wherein one of the first and second elastomer regions (11, 12) surrounds the other elastomer region radially on the outside and wherein the second elastomer material has a greater modulus of elasticity than the first elastomer material at lower temperatures and the first elastomer material has a greater modulus of elasticity than the second elastomer material at higher temperatures.

2. Prestressing element according to claim 1, characterized in that the first elastomer material has more compressive stresses at higher temperatures than the second elastomer material.

3. Prestressing element according to claim 1 or 2, characterized in that the second elastomer material has a modulus of elasticity at lower temperatures that is at least 1.1 times greater than that of the first elastomer material.

4. Prestressing element according to one of the preceding claims, characterized in that the second elastomer material has a larger compression set at higher temperatures, in particular a compression set that is at least 1.1 times as large as that of the first elastomer material.

5. Prestressing element according to one of the preceding claims, characterized in that the lower temperatures comprise a temperature range between -60° and -20 °C, in particular between -60 °C and 0 °C.

6. Prestressing element according to one of the preceding claims, characterized in that the higher temperatures are greater than 120°, in particular greater than 50 °C.

7. Prestressing element according to one of the preceding claims, characterized in that the first and the second elastomer region (11, 12) are two separate parts and one of the two parts is received in a circumferential geometry of the other part, in particular in a groove (6) or annular groove (7).

8. Prestressing element according to one of claims 1 to 6, characterized in that the first and the second elastomer region (11, 12) are integrally connected to one another.

9. Prestressing element according to claim 8, characterized in that one of the first and second elastomer regions (11, 12) is partially or completely embedded in the other elastomer region.

10. Prestressing element according to one of the preceding claims, characterized in that the first elastomer region (11) has at least one sealing zone (13) on its side facing away from the second elastomer region (12) and that the sealing zone (13) and the second elastomer region (12) are arranged at least in sections at the same axial height with respect to a longitudinal axis (5) of the prestressing element (10).

11. Prestressing element according to one of claims 1 to 9, characterized in that the first elastomer region (10) has two axially spaced sealing zones (13) on its side facing away from the second elastomer region (12) and that the second elastomer region (12) is arranged axially between the two sealing zones (13).

12. Prestressing element according to one of the preceding claims, characterized by at least two second elastomer regions (12) arranged axially spaced apart from one another.

13. Prestressing element according to one of the preceding claims, characterized in that the first elastomer region (11) and / or the second elastomer region (12) has a round, a rectangular, in particular square, a club-shaped or an X-shaped cross-section.

14. Prestressing element according to one of the preceding claims, characterized in that the second elastomer region (12) has a plurality of circumferential elastomer sections (21-23) each made of different second elastomer materials.

15. Prestressing element according to one of the preceding claims, characterized in that the first elastomer material comprises or consists of one or more of the following materials: NBR, HNBR, AEM, FKM, FFKM and VMQ.

16. Prestressing element according to one of the preceding claims, characterized in that the second elastomer material comprises or consists of one or more of the following materials: NBR, FFKM and VMQ.

17. Prestressing element according to one of the preceding claims, characterized in that the axial width (bA) of the outer elastomer region (12) is smaller than half the axial width (BA) of the inner elastomer region (11).

18. Prestressing element according to one of the preceding claims, characterized in that the radial thickness (dR) of the outer elastomer region (12) is smaller than half the radial distance (AR) between the radial inner side (11a) of the inner elastomer region (11) and the radial inner side (12a) of the outer elastomer region (12).

19. Sealing arrangement (1; 1'), in particular a rod or piston sealing arrangement, with a first machine part (2) and with a second machine part (3), which are movable in a translational or rotational manner relative to one another, with a seal (4) which is arranged between the two machine parts (2, 3) in order to seal the two machine parts (2, 3) against one another, and with a prestressing element (10) according to one of the preceding claims, which prestresses the seal (4) radially against one of the two machine parts (2, 3).

20. Sealing arrangement according to claim 19, characterized in that the prestressing element (10) bears against the seal (4) exclusively with its first elastomer region (11).

21. Sealing arrangement according to claim 19 or 20, characterized in that a second elastomer region (12) of the prestressing element (10) facing away from the seal (4) is arranged at the same axial height as a sealing zone (6) of the seal (4) lying against the machine part (2).

22. Sealing arrangement according to one of claims 19 to 21, characterized in that the prestressing element (10) prestresses the seal (2) radially inwards or outwards.

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