DE102023121966A1 - Preloading element made of two different elastomer materials for radial preloading of a seal and associated sealing arrangement - Google Patents

Abstract

According to the invention, a prestressing element (10) for radially prestressing 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 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 larger modulus of elasticity than the first elastomer material at lower temperatures and the first elastomer material has a larger modulus of elasticity than the second elastomer material at higher temperatures.

Description

The present invention relates to a preloading element, in particular a preloading ring or a preloading sleeve, made of elastomer material for radially preloading a seal, as well as a sealing arrangement with two machine parts, with a seal for sealing between the two machine parts and with a preloading element which 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.

Typically, elastomers have a temperature window within which they can be used. The lower temperature limit is given by the Temperature Reaction Test (TR) and the Glass Transition Temperature (TG), whereas the upper temperature limit is given by the Compression Set. Compression set is a measure of how elastomers behave under long-term, constant compression deformation and subsequent relaxation. As elastomers are compacted over time, they lose the ability to return to their original thickness.

Typical high-temperature materials, such as those used in sealing technology, have high elasticity and good compression set at high temperatures (T > 50 °C) and low elasticity at low temperatures (T < -20 °C). The following temperature windows are specified in data sheets for such high-temperature materials: NBR (nitrile butadiene rubber) -30 °C to 100 °C; HNBR (hydrogenated nitrile butadiene rubber) -25 °C to 140 °C; AEM (acrylate-ethylene-polymethylene rubber) -40 °C to 160 °C; FKM (fluoropolymer rubber) -20 °C to 200 °C; FFKM (perfluorocarbon rubber) 55 °C to 330 °C; and VMQ (silicone rubber) -60 °C to 250 °C.

In contrast, typical low-temperature materials, such as those used in sealing technology, have good elasticity at low temperatures (-60 °C <T < 0 °C) and a high compression set at high temperatures (T > 50 °C). The following temperature windows are specified in data sheets for such low-temperature materials: NBR (nitrile butadiene rubber) -54 °C to 80 °C; HNBR (hydrogenated nitrile butadiene rubber) -25 °C to 140 °C; EPDM (ethylene-propylene-diene (monomer) rubber) -50 °C to 120 °C; AU (polyurethane rubber) -40 °C to 90 °C; CR (chloroprene rubber) -20 °C to 120 °C.

The high compression set means that a seal or preload element made of such a low-temperature material often becomes faulty after the first or second summer due to the high temperatures (high ambient temperature plus process temperature, e.g. of a hydraulic system or an internal combustion engine). In the automotive, truck or bus sector, as well as in the field of mobile work machines, for example, this can lead to a conflict, as materials such as AEM with a glass transition temperature of -31°C do not have the necessary elasticity at low temperatures to simultaneously meet both the low-temperature requirements (-40°C) and the high-temperature requirements (+140°C).

The elastic modulus describes the behavior of a material when a compressive force is applied. The higher the elastic modulus, the higher the force required to compress the material. The elastic modulus of a material depends on the temperature.

In contrast, 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.

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, wherein one of the first and second elastomer regions surrounds the other elastomer region radially on the outside and wherein the second elastomer material has a larger modulus of elasticity than the first elastomer material at lower temperatures and the first elastomer material has a larger 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 compared to the first elastomer material.

According to the invention, the operating temperature range of the prestressing element is increased by combining elastomer materials with different rubber-elastic properties. The two elastomer materials preferably have opposing temperature behavior with regard to their elasticity. The second elastomer region can be used both for static sealing and for prestressing the seal at low temperatures. Because the first elastomer region has its temperature application range at high temperatures, compression of the second elastomer region at high temperatures is also less severe, which increases the service life of the prestressing element. At high temperatures, which can lead to compression set over time, the first elastomer material can compensate for the compression set of the second elastomer material due to its elasticity.

Preferably, the second elastomer material has a modulus of elasticity that is at least twice as large as the first elastomer material at lower temperatures and a larger compression set at higher temperatures, in particular a compression set that is at least twice as large as the first elastomer material.

The lower temperatures preferably cover a temperature range between -60° and -20 °C, in particular between -60 °C and 0 °C, and the higher temperatures are preferably greater than 120°, in particular greater than 50 °C.

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 groove or annular groove of the other part. An embodiment is particularly preferred wherein 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.

In another preferred embodiment, the first and second elastomer regions are integrally connected to one another, wherein one of the first and second elastomer regions can be partially or completely embedded in the other elastomer region.

Preferably, the first elastomer region has at least one sealing zone on its side facing away from the second elastomer region, wherein the sealing zone and the second elastomer region are arranged at least in sections at the same axial height with respect to a longitudinal axis of the prestressing element for a maximum pressing effect. In the case that 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 for a maximum pressing effect.

In addition, the second elastomer region forms at least one sealing zone on the side facing away from the first elastomer region. This sealing zone is preferably arranged radially on the outside or radially on the inside. It is advantageous that the first elastomer region also forms a sealing zone axially adjacent to this sealing zone, i.e. also radially on the outside or radially on the inside. This enables reliable static sealing in a wide temperature range.

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 have at least one sealing zone of the first elastomer region can be prestressed radially. In the event that 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 pressing effect.

The first and/or the second elastomer region can in principle have any cross-section, but preferably has a substantially round, rectangular, in particular square, club-shaped or X-shaped cross-section. The club-shaped and X-shaped cross-sections each have a circumferential groove on the inside and outside, in which an elastomer ring can be inserted.

In order to be able to individually tailor the preload by the preload element over the largest possible range, the first elastomer area and/or the second elastomer area can each have several circumferential elastomer sections made of different first or second elastomer materials. The materials and dimensions of the individual elastomer sections are selected so that the desired preload behavior is achieved.

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.
The preloading element described above is configured for radial preloading of a seal. It is known to those skilled in the art that this preloading element can also be used for axial preloading. In the preloading element according to the invention, one of the first and second elastomer regions surrounds the other elastomer region radially on the outside. When used for axial preloading, one of the first and second elastomer regions surrounds the other elastomer region on one axial side.

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 movable relative to one another in a translational or rotational manner, with a seal which is arranged between the two machine parts in order to seal the two machine parts against one another, and with a prestressing element as described above, which prestresses the seal radially inwards or outwards against one of the two machine parts.

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.

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.

Further advantages and advantageous embodiments of the subject matter of the invention can be found in the description, the drawing and the claims. The features mentioned above and those listed below can also be used individually or in combination in any desired way. The embodiments shown and described are not to be understood as an exhaustive list, but are merely exemplary in nature for the description of the invention.

• 1a-1d Querschnitte von verschiedenen erfindungsgemäßen Vorspannringen mit einem runden, inneren Elastomerbereich und einem äußeren Elastomerbereich, dessen Breite kleiner als die halbe Breite des inneren Elastomerbereichs ist, für jeweils vier unterschiedliche Querschnitte des äußeren Elastomerbereichs;
• 2a-2d Querschnitte von verschiedenen erfindungsgemäßen Vorspannringen mit einem quadratischen, inneren Elastomerbereich und mit einem äußeren Elastomerbereich, dessen Breite kleiner als die halbe Breite des inneren Elastomerbereichs ist, für jeweils vier unterschiedliche Querschnitte des äußeren Elastomerbereichs;
• 3a-3d Querschnitte von verschiedenen erfindungsgemäßen Vorspannringen mit einem keulenförmigen, inneren Elastomerbereich und mit einem äußeren Elastomerbereich, dessen Breite kleiner als die halbe Breite des inneren Elastomerbereichs ist, für jeweils vier unterschiedliche Querschnitte des äußeren Elastomerbereichs;
• 4a-4d Querschnitte von verschiedenen erfindungsgemäßen Vorspannringen mit einem X-förmigen, inneren Elastomerbereich und mit einem äußeren Elastomerbereich, dessen Breite kleiner als die halbe Breite des inneren Elastomerbereichs ist, für jeweils vier unterschiedliche Querschnitte des äußeren Elastomerbereichs;
• 5a-5d Querschnitte von verschiedenen erfindungsgemäßen Vorspannringen mit einem runden, inneren Elastomerbereich und mit einem äußeren Elastomerbereich, dessen Breite größer als die halbe Breite des inneren Elastomerbereichs ist, für jeweils unterschiedliche Querschnitte des äußeren Elastomerbereichs;
• 6a-6d Querschnitte von verschiedenen erfindungsgemäßen Vorspannringen mit einem X-förmigen, inneren Elastomerbereich und mit zwei axial beanstandeten, gleichen äußeren Elastomerbereichen, deren Breite jeweils kleiner als die halbe Breite des inneren Elastomerbereichs ist, für jeweils vier unterschiedliche Querschnitte der äußeren Elastomerbereiche;
• 7a-7d Querschnitte von verschiedenen erfindungsgemäßen Vorspannringen mit einem keulenförmigen, inneren Elastomerbereich und mit zwei axial beanstandeten, gleichen äußeren Elastomerbereichen, deren Breite jeweils kleiner als die halbe Breite des inneren Elastomerbereichs ist, für jeweils vier unterschiedliche Querschnitte der äußeren Elastomerbereiche;
• 8a-8d Querschnitte von verschiedenen erfindungsgemäßen Vorspannringen mit einem runden, ersten Elastomerbereich und mit vier gleichen zweiten Elastomerbereichen, deren Breite jeweils kleiner als die halbe Breite des inneren Elastomerbereichs ist, für jeweils vier unterschiedliche Querschnitte der zweiten Elastomerbereiche;
• 9a-9c Querschnitte von zwei erfindungsgemäßen Vorspannringen mit einem runden, inneren Elastomerbereich und mit jeweils unterschiedlichen äußeren Elastomerbereichen (9a, 9b) sowie die zugehörige Pressungsverteilung der beiden Vorspannringe ( 9c);
• 10a-10d eine Stangen-Dichtungsanordnung mit einer Dichtung sowie mit einem herkömmlichen Vorspannring (10a) und mit einem erfindungsgemäßen Vorspannring (10b-10d) zum Vorspannen der Dichtung radial nach innen;
• 11a-11d eine Kolben-Dichtungsanordnung mit einer Dichtung sowie mit einem herkömmlichen Vorspannring (11a) und mit einem erfindungsgemäßen Vorspannring (11b-11d) zum Vorspannen der Dichtung radial nach außen;
• 12a-12c eine Kolben-Dichtungsanordnung mit einer Dichtung und mit einem modifizierten erfindungsgemäßen Vorspannring zum Vorspannen der Dichtung radial nach außen; und
• 13a-13d eine Rotationsdichtungsanordnung mit zwei axial beabstandeten Dichtungen sowie mit einer erfindungsgemäßen Vorspannhülse mit einem hülsenförmigen, inneren Elastomerbereich und mit zwei axial beanstandeten, gleichen äußeren Elastomerbereichen zum Vorspannen der beiden Dichtungen radial nach innen, für jeweils vier unterschiedliche Querschnitte der zweiten Elastomerbereiche.

They show:

• 1a-1d Cross sections of various preload 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;
• 2a-2d 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;
• 3a-3d Cross sections of various prestressing rings according to the invention with a club-shaped, inner elastomer region and with an outer elastomer region whose width is smaller than the half the width of the inner elastomer region, for each of four different cross-sections of the outer elastomer region;
• 4a-4d Cross sections of various prestressing rings 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;
• 5a-5d Cross sections of various prestressing rings 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;
• 6a-6d Cross sections of various preloading rings according to the invention with an X-shaped, inner elastomer region and with two axially spaced, identical outer elastomer regions, the width of each of which is less than half the width of the inner elastomer region, for each of four different cross sections of the outer elastomer regions;
• 7a-7d Cross sections of various prestressing rings according to the invention with a club-shaped, inner elastomer region and with two axially spaced, identical outer elastomer regions, the width of each of which is less than half the width of the inner elastomer region, for each of four different cross sections of the outer elastomer regions;
• 8a-8d Cross sections of various prestressing rings according to the invention with a round, first elastomer region and with four identical second elastomer regions, the width of which is each smaller than half the width of the inner elastomer region, for each of four different cross sections of the second elastomer regions;
• 9a-9c Cross sections of two preload rings according to the invention with a round, inner elastomer area and with different outer elastomer areas ( 9a , 9b) and the corresponding pressure distribution of the two preload rings ( 9c );
• 10a-10d a rod seal arrangement with a seal and a conventional preload ring ( 10a) and with a preload ring according to the invention ( 10b-10d ) to preload the seal radially inwards;
• 11a-11d a piston seal arrangement with a seal and a conventional preload ring ( 11a) and with a preload ring according to the invention ( 11b-11d ) to preload the seal radially outwards;
• 12a-12c a piston seal arrangement with a seal and with a modified preloading ring according to the invention for preloading the seal radially outward; and
• 13a-13d 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 four different cross-sections of the second elastomer regions.

1a-1d show various preloading elements, here preloading rings 10, for radial preloading of a seal 4 ( 10-13 ), with a first, here inner elastomer region 11 made of a first elastomer material and with a 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 a width that is less than half the width of the inner elastomer region 11. The inner elastomer region 11 has an inner sealing zone 13 running all the way around. 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 preloading ring 10, so that the inner sealing zone 13 and the outer elastomer region 12 lie on the same (radial) line of action.

The preload ring 3 has in 1a a round, in 1b a square, in 1c a club-shaped and in 1d an X-shaped cross-section.

In the temperature range between -60 °C and 120 °C, the second elastomer material has a larger modulus of elasticity (compression modulus) than the first elastomer material at lower temperatures (-60 °C < T < -20 °C, in particular -60 °C < T < 0 °C) and the first elastomer material has a larger modulus of elasticity (compression modulus) than the first elastomer material at higher temperatures (50 °C < T < 120 °C). dul) than the second elastomer material. In particular, the second elastomer material can have its maximum modulus of elasticity in a different temperature range than the first elastomer material.

In other words, the first elastomer material of the inner elastomer region 11 is a high-temperature material that has a higher elasticity and a higher compression set at high temperatures (50 °C < T < 120 °C) and a 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 has a higher elasticity and a higher compression set at low temperatures (-60 °C < T < -20 °C) and a lower elasticity and a lower compression set at high temperatures (50 °C < T < 120 °C).

Preferably, the second elastomer material has a modulus of elasticity that is at least twice as large as 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 the first elastomer material at temperatures higher than 120 °C, preferably at temperatures higher than 50 °C.

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

The first and second elastomer regions 11, 12 may, for example, be separate parts, in which case the outer elastomer region 11 is arranged in a radially outwardly open groove 15 ( 3a-3d ) or ring groove 16 ( 9a , 9b) the inner elastomer region 11. Alternatively, the first and second elastomer regions 11, 12 can also be materially bonded 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.

The required elasticity or preload 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.

Of the preload rings 10 of the 1a-1d differ in 2a-2d shown preload rings 10 only in that the inner elastomer region 11 has a square cross-section.

Of the preload rings 10 of the 1a-1d differ in 3a-3d shown preload rings 10 only in that here the inner elastomer region 11 has a club-shaped cross-section with two all-round, axially spaced, inner sealing zones 13. The outer elastomer region 12 is arranged axially centrally between the two sealing zones 13.

Of the preload rings 10 of the 3a-3d differ in 4a-4d shown preload rings 10 only in that 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.

Of the preload rings 10 of the 1a-1d differ in 5a-5d shown preload rings 10 only in that the width of the outer elastomer region 12 is significantly larger than half the width of the inner elastomer region 11.

6a-6d show various preload rings 10 with an X-shaped, inner elastomer area 11 made of the first elastomer material and two axially spaced, outer elastomer areas 12 made of the second elastomer material. The width of the outer elastomer areas 12 is significantly smaller than half the width of the inner elastomer area 11. The two outer elastomer areas 12 are each arranged at the axial heights of the two all-round, axially spaced, inner sealing zones 13 of the inner elastomer area 11, so that the inner sealing zones 13 and the outer elastomer areas 12 are each located on the same (radial) lines of action. The two outer elastomer areas 12 have in 6a the same round, in 6b the same square, in 6c the same club-shaped and in 1d the same X-shaped cross-section.

Of the preload rings 10 of the 6a-6d differ in 7a-7d shown preload rings 10 only in that the inner elastomer region 11 has a club-shaped cross-section.

Of the preload rings 10 of the 1a-1d differ in 8a-8d shown preload rings 10 only in that here additionally three further 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 in 8a a round, in 8b a square, in 8c a club-shaped and in 8d an X-shaped cross-section.

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 with the same cross-sectional radius is arranged, namely in 9a a round elastomer ring 17 and in 9b a round elastomer ring 17' with a flattened outer surface. Like the 9c As shown in the corresponding pressure distribution of the two pre-tensioning rings 10, the pressure P acting on the sealing zone 13 in the installed state can be varied and adjusted over the width b of the pre-tensioning ring 10 by varying the cross-sectional geometry of the elastomer ring 17, 17' or the outer elastomer area 12. Thus, the pressure P shown in 9a The round elastomer ring 17 shown in the middle area has a significantly higher pressure than the one in 9b shown, flattened elastomer ring 17'.

For the preload rings 10 of the 1-9 the first elastomer region 11 is arranged on the inside and the second elastomer region(s) 12 is arranged on the outside in order to prestress the sealing ring 2 radially inwards. In further below in 11 and 12 The embodiments shown can - exactly the opposite of what is shown in the 1-9 - the first elastomer region 11 is arranged on the outside and the second elastomer region(s) 12 is arranged on the inside in order to prestress the sealing ring 2 radially outward. Such embodiments are referred to below as reversed embodiments.

10a-10d show a rod sealing arrangement 1, which is mainly used in cylinders and serves to seal liquids. It prevents hydraulic fluid from escaping from the cylinder chamber and is mounted outside the cylinder head. The rod sealing arrangement 1 comprises a first (inner) machine part 2, here for example in the form of a rod or shaft, a second (outer) machine part 3, which can be moved relative to one another in a translational or rotational manner, an annular primary seal 4 and a conventional preload ring 110 ( 10a) or a preload ring 10 designed as above ( 10b-10d ) for pre-tensioning the primary seal 4 radially inwards. The primary seal 4 and the pre-tensioning 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 pre-tensioning ring 10 presses the primary seal 4 radially inwards and thus into contact with the shaft 2. In other words, the primary seal 4 is used for dynamic sealing with the shaft 2 and the pre-tensioning 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 inwards against the shaft 11.

In the 10a The conventional preload ring 110 shown in Figure 1 is a round preload ring made of a single elastomer material, e.g. a high temperature material such as NBR, HNBR, AEM or FKM. 10b The preload ring 10 shown is the one in 1a shown preload ring, but instead any other of the ones in 1-9 The preload rings 10 shown in 9c As shown, the pressure acting radially inward on an inner sealing zone (sealing edge) 6 of the primary seal 4 can be varied and adjusted by varying the cross-sectional geometry of the second elastomer region(s) 12 of the preload ring 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.

In the 10c In the preload ring 10 shown, the inner elastomer region 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 case of the preload ring 10 shown in 10d In the preload ring 10 shown, the inner elastomer area 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 be in the corner area between the two groove flanks and the groove base each have an inclined ramp 8, which ensures that a temperature-dependent change in the preload force can be set even when the inner elastomer area 11 is stiffened.

11a-11d show a piston seal arrangement 1', which is mainly used in hydraulic cylinders as a fluid seal. The installation spaces are inside the cylinder and serve to seal the piston against the cylinder tube. The piston seal arrangement 1' comprises a first (outer) machine part 2, a second (inner) machine part 3, here for example in the form of a piston, which can be moved relative to one another in a translational or rotational manner, a primary seal 4 and a conventional preload ring 110 ( 11a) or a preload ring 10 designed as above ( 11b-11d ) for pre-tensioning the primary seal 4 radially outwards. The primary seal 4 and the pre-tensioning 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 pre-tensioning 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.

In the 11a The conventional preload ring 110 shown in Figure 1 is a round preload ring made of a single elastomer material, e.g. a high temperature material such as NBR, HNBR, AEM or FKM. 11b The preload ring 10 shown is the one opposite 1a inverted preload ring 10 with a first, here outer, round elastomer area 11 and a second, here inner, round elastomer area 12, but instead any other opposite to the 1-9 reversed preload ring 10 can be used. Analogous to 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 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.

In the 11c In the preload ring 10 shown, the second elastomer region 12 has a rectangular cross-section. Instead of being trapezoidal as in the 11a-11c , indicates the 11d The primary seal 4 shown has a rectangular cross-section with bevelled inner corners.

From the piston seal arrangement 1' of the 11d differ in 12a-12c shown piston sealing arrangement 1' only in that here the second elastomer area 12 in 12a two circumferential elastomer sections 21, 22 each made of different second elastomer materials and in 12b , 12c three circumferential elastomer sections 21, 22, 23 each made of different second elastomer materials. In 12a the two elastomer sections 21, 22 are formed by two lateral halves, and in 12b , 12c In addition, an inner elastomer section 23 is 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, 12c an outer second elastomer region 12' made of different second elastomer materials is arranged in the preload ring 10.

It goes without saying that the 1-10 The second elastomer region shown can analogously have several elastomer sections all around, each made of different materials.

The in 13a-13d The rotary seal arrangement 1 shown comprises a first (inner) machine part 2, here for example in the form of a rod or shaft, a second (outer) machine part 3, which are movable relative to each other in a translational or rotational manner, two axially spaced primary seals 4, each with a support body 24 arranged on the outside, against which the primary seal 4 rests laterally in the axial direction, and a 7 formed, club-shaped preload ring or sleeve 10. 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 inwards 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 which is delimited by the shaft 2, the primary seals 4 and the inside of the preload sleeve 10. The required elasticity or preload 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.

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

When a pressurized fluid is introduced into the interior 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 of a high pressure prevailing in the interior 26 (high pressure area H) compared to a low pressure prevailing in the low pressure area N is exceeded. The support bodies 24 are axially displaced outwards in the direction of the low pressure side N under an elastic deformation of the preload sleeve 10 to such an extent that the primary seals 4 with their respective sealing edges 27 seal against the shaft 3 in a radial direction, thereby causing a fluid-tight seal of the high pressure area H. The adjustment movement of the support bodies 24 can, if they are made of a viscoelastic material, be at least partially caused by a section-wise (elastic) deformation of the support bodies 24 in the direction of the low pressure area N. If the differential pressure falls below the specified value, the support bodies 24 are returned in the axial direction to the position specified in 13 shown resting position.

Claims (18)

Prestressing element (10), in particular prestressing ring or sleeve, made of elastomer material 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 larger modulus of elasticity than the first elastomer material at lower temperatures and the first elastomer material has a larger modulus of elasticity than the second elastomer material at higher temperatures. prestressing element according to claim 1 , characterized in that the second elastomer material has a modulus of elasticity at lower temperatures that is at least twice as high as the first elastomer material. preloading element according to claim 1 or 2 , characterized in that the second elastomer material has a larger compression set at higher temperatures, in particular a compression set that is at least twice as large as the first elastomer material. 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. 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. 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 groove (6) or annular groove (7) of the other part. Prestressing element according to one of the preceding claims, characterized in that the first and the second elastomer region (11, 12) are connected to one another in a materially bonded and/or positively locking manner. preloading element according to claim 7 , characterized in that one of the first and second elastomer regions (11, 12) is partially or completely embedded in the other elastomer region. 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). Prestressing element according to one of the Claims 1 until 8 , 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). 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. 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. 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 plurality of circumferential elastomer sections (21-23) each made of different elastomer materials. 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. 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, HNBR, EPDM, AU and CR. 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 relative to one another in a translational or rotational manner, 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 radially prestresses the seal (4) against one of the two machine parts (2, 3). Seal arrangement according to claim 16 , characterized in that the prestressing element (10) rests against the seal (4) exclusively with its first elastomer region (11). Seal arrangement according to claim 16 or 17 , 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) adjacent to the machine part (2).

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