Slip ring gasket arrangement

Abstract

The invention relates to a sliding ring sealing system, comprising: a sliding ring seal (2) having a rotating sliding ring (3) with a first sliding surface (30) and a stationary sliding ring (4) with a second sliding surface (40), a sealing gap (5) being defined between the sliding surfaces (30, 40);a torsion device (6) for transferring torque between one of the slip rings and a slip ring carrier (31, 41), the torsion device (6) having a plurality of transfer elements (60, 70) configured to transfer torque between the slip ring carrier (31, 41) and the slip ring such that a total torque is distributed over the plurality of transfer elements (60, 70), the slip ring carrier (31, 41) having first receiving openings (61) with an arcuate cross-section when viewed from a cross-sectional point of view, and the slip ring having second receiving openings (62) with an arcuate cross-section when viewed from a cross-sectional point of view, the transfer elements (60, 70) being arranged in the first and second receiving openings (61, 62).

Description

[0001] The present invention relates to a mechanical seal arrangement with a significantly improved possibility of transmitting torque to and from sliding rings, in particular ceramic sliding rings.

[0002] Mechanical seal assemblies are known in various configurations from the prior art. One challenge is starting the mechanical seal from a standstill under high pressure of the medium being sealed. When the mechanical seal assembly is at rest, the seal rings are typically pressed against each other by springs and the pressure of the medium to ensure a seal at the sealing gap between the sliding surfaces of the seal rings. Generally, the seal is better the higher the axial preload on the seal rings. However, this leads to problems when starting the mechanical seal assembly from a standstill, as a very high torque occurs, which is transmitted from the starting shaft, via a seal carrier, for example, to the rotating seal ring.Similarly, due to contact during start-up of the mechanical seal assembly when stationary, a very high torque occurs on the stationary sliding ring, which is held in place by a stationary sliding ring carrier or a housing. The same problem also occurs with mechanical seals used to seal media, especially at high pressures, for example in pumps or agitator seals, because the sliding rings are additionally stressed by the high pressure when stationary and are pressed against each other. Press-fit pins are used, for example, to transmit torque between the sliding ring carrier and the sliding ring. However, this is not possible with ceramic sliding rings due to the brittleness of the material.Shrink-fit connections between the sliding ring carrier and the sliding ring are also known, but these can introduce undesirably high stresses into the sliding ring, which can lead to cracks in the sliding ring material and potentially an undesirably short service life of the sliding rings. Particularly with agitator seals, additional so-called standstill seals are often necessary to ensure the tightness of the mechanical seal assembly when the system is at rest.

[0003] DE 10 2016 210 202 A1 and DE 195 81 720 T1 disclose mechanical seal arrangements according to the preamble of the independent claims.

[0004] DE 76 31 330 U1 discloses a mechanical seal for carbon rings with elastic torque transmission elements.

[0005] It is therefore an object of the present invention to provide a mechanical seal arrangement which, with a simple design and simple, cost-effective manufacturability, enables an improvement in the transmission of torque between sliding rings and sliding ring carriers in both rotating and stationary sliding rings.

[0006] This problem is solved by a mechanical seal arrangement having the features of claim 1. The dependent claims describe preferred embodiments of the invention.

[0007] In contrast, the mechanical seal arrangement according to the invention with the features of claim 1 has the advantage that a significant improvement in torque transmission between the sliding ring carrier and the sliding ring, or between the sliding ring and the sliding ring carrier, is possible. In particular, damage to the sliding rings caused by excessively high torques can be avoided. Furthermore, no additional standstill seals are necessary. Moreover, according to the invention, a very gentle torque application between the torque-transmitting components can be achieved. Furthermore, a force application point K can be specifically selected, whereby in particular a direction of the force and / or a magnitude of the applied force can be defined.

[0008] According to the invention, this is achieved by the mechanical seal assembly comprising a mechanical seal which has a rotating sliding ring with a first sliding surface and a stationary sliding ring with a second sliding surface, wherein a sealing gap is defined between the sliding surfaces. Furthermore, the mechanical seal assembly comprises a torque device for introducing torque into and / or out of at least one of the sliding rings. The torque device has a plurality of transmission elements which transmit torque between a sliding ring carrier and the sliding ring. Torque can be transmitted in both directions, i.e., from the sliding ring carrier to the sliding ring or from the sliding ring to the sliding ring carrier. The torque transmission is carried out such that a total torque is distributed among the plurality of individual transmission elements.The sliding ring carrier has first receiving openings with an arcuate cross-section. The sliding ring has second receiving openings with an arcuate cross-section. The first and second receiving openings are preferably semicircular in cross-section. Furthermore, the transmission elements are arranged simultaneously in the first and second receiving openings and are in contact with the sliding ring carrier and the sliding ring. There is no interference fit between the transmission elements and the first and second receiving openings. Since a plurality of transmission elements are provided, and all transmission elements participate in the torque transmission, a significant reduction in the magnitude of the transmitted torque is achieved, corresponding to the number of transmission elements at a given maximum torque. Stresses at the contact areas of the torque device can also be reduced.

[0009] Furthermore, the rolling elements, which are arranged between the sliding ring carrier and the sliding ring, perform a rolling motion during torque transmission. This rolling motion is relatively small during operation and is only carried out over a small angle of rotation, preferably less than 2°, and particularly less than 1°.

[0010] The rolling elements are preferably cylinders. Preferably, all rolling elements are identical. The cylinders are arranged with their cylinder axis parallel to the central axis of the mechanical seal. This allows for a rolling motion in the circumferential direction of the sliding rings, resulting in a variation of the force application point K between the torque-transmitting components. The rolling elements allow the force application point to be moved away from the outer diameter of the sliding ring and thus away from a fragile edge at the receiving openings provided on the outer circumference of the sliding ring. This prevents stress concentrations that could potentially lead to chipping of the sliding ring material, particularly in the area of ​​the receiving openings. This is especially advantageous when using ceramic sliding rings.

[0011] Preferably, the first radius R1 of the rolling elements is smaller than the second radius R2 of the first receiving openings in the sliding ring carrier and / or the first radius R1 of the rolling elements is smaller than the third radius R3 of the second receiving openings in the sliding ring. That is, at the point of contact, the first radius R1 is always less than or equal to the second radius R2 and / or the third radius R3. This allows the direction of the force acting on the component receiving the torque to be set. In particular, the force application point K can be moved away from an outer circumference of the sliding ring where the edge of the second receiving opening is located.Furthermore, when starting up the mechanical seal assembly from a standstill, the choice of different radii for the rolling elements and the receiving openings can cause a brief deformation of the sliding surface in the area between two adjacent rolling elements. This allows, especially at high pressures, the pressurized medium to be sealed to briefly flow into this deformation of the sliding surface, thus assisting in the lifting of the sliding rings.By selecting the force application point K, a certain waviness on the sliding surface, especially on the pressure-loaded side, particularly on the outer circumference of the sliding ring, can be specifically achieved for the start-up process of the mechanical seal assembly. This waviness leads to recessed valleys in the area of ​​the rolling elements and to protruding bulges in the area between the rolling elements in the axial direction of the sliding surface, so that the medium can briefly flow into the sealing gap and supports the lifting of the sliding surfaces during the start-up process.

[0012] Preferably, the radii R2 and R3 of the second and third receiving apertures are the same size.

[0013] In a further preferably alternative embodiment according to claim 5 of the invention, the transmission elements comprise a first and a second body which are connected to each other by means of a connecting device. The first body has an arc-shaped first contact surface for contact with the first receiving opening in the sliding ring carrier, and the second body has an arc-shaped second contact surface for contact with the second receiving opening in the sliding ring.

[0014] Preferably, the connecting device between the first and second bodies comprises one or more rods. This means that the first and second bodies are only connected to each other in certain areas, so that the transmission elements thus designed possess a certain degree of elasticity. Particularly preferably, the rods and / or the first and second bodies are made of a material with greater elasticity than the sliding ring and the sliding ring carrier. Further preferably, the connecting device comprises a truss-like connection that is particularly rigid in the radial direction.

[0015] The first body and / or the second body are preferably rod-shaped components, particularly with an elliptical cross-section. Alternatively, it is also possible for the first and second bodies to be designed as cylinders, preferably with different diameters.

[0016] Furthermore, the first and second bodies preferably have different cross-sections.

[0017] Preferably, the first and second receiving openings are arranged in an N-gon, where N is an integer. Particularly preferred is N = 6, with the torque-initiating positions being evenly distributed along the circumference of the sliding ring. Torque transmission to and from the sliding ring preferably occurs at the outer circumference of the sliding ring.

[0018] Torque devices for transmitting torque are preferably provided on both the rotating and the stationary sliding ring. The torque devices on the rotating and stationary sliding rings preferably have the same geometric shape.

[0019] Furthermore, especially when the machine is started up and thus at the beginning of the rotation of the shaft, a support torque M2 arises between the stationary sliding ring 4 and the second sliding ring carrier 41, which must also be transmitted between these two components by a torque device 6.

[0020] The torque device 6 between the rotating sliding ring 3 and the first sliding ring carrier 31 is shown in detail in the Fig. 1 and 2 As can be seen. The torque device 6 comprises a plurality of transmission elements 60, which in this embodiment are cylindrical rolling elements. As shown Fig. 2 As can be seen, a total of six rolling elements are arranged evenly distributed along the circumference between the rotating sliding ring 3 and the first sliding ring carrier 31.

[0021] The transmission elements 61 are designed to transmit torque between the first sliding ring carrier 31 and the rotating sliding ring 3. The total torque M1 is distributed among the multiple transmission elements 61 of the same size.

[0022] As from the Fig. 1 and 2 As can be further seen, the first sliding ring carrier 31 has first receiving openings 61 with an arcuate cross-section. The rotating sliding ring 3 has second receiving openings 62 with an arcuate cross-section. The transmission elements 60 are arranged in both the first and second receiving openings 61, 62.

[0023] What's next? Fig. 2As can be seen, the cylindrical transmission element 60 has a first radius R1, the first receiving opening 61 in the first sliding ring carrier 31 has a second radius R2, and the second receiving opening 62 in the rotating sliding ring 3 has a third radius R3. The first radius R1 is smaller than the second radius R2 and smaller than the third radius R3. Furthermore, the second radius R2 and the third radius R3 are equal in size.

[0024] As from Fig. 1As can be seen, the selection of the three radii R1, R2, and R3 results in a rolling motion of the transmission elements 60 in the first and second receiving openings 61 and 62 when the mechanical seal assembly starts up from its rest position. A force application point K can be defined by selecting the size of the radii R1, R2, and R3. Since the first radius R1 is smaller than the two radii R2 and R3, the force application point K is located at a distance A from an edge of the second receiving opening 62 in the rotating sliding ring 3. This prevents the forces F, which occur particularly during the start-up process of the mechanical seal assembly, from acting on the edge of the second receiving opening 62, thus avoiding chipping or cracking in this sensitive area of ​​the sliding ring. Therefore, the force application point K can be positioned away from the outer circumference of the sliding ring, thus reducing stress peaks that could lead to chipping or similar damage.This could prevent problems with the sliding ring.

[0025] Furthermore, the design of the transmission elements 60 as rolling elements ensures that during the start-up process a short rolling process of the transmission elements 60 from the rest position occurs, so that a uniformly distributed and thus smooth introduction of the torque from the first sliding ring carrier 31 to the rotating sliding ring 3 takes place.

[0026] Furthermore, by adjusting the direction of force F to a tangent T at an angle α during the start-up process, an additional radial force can be provided at each first receiving opening 61 by the torque M1. This allows for a targeted, short-term, torque-active deformation of the sliding surface 30 of the rotating sliding ring, particularly at the outer circumference of the rotating sliding ring, resulting in a certain degree of waviness during the start-up process of the sliding surface 30. This can provoke a short-term ingress of medium from the product area 11 under high pressure into the sealing gap 5, which, in addition to the start-up torque, contributes to breaking the sliding surfaces apart from their resting state in order to form the sealing gap 5 between the sliding surfaces 30 and 40 as quickly as possible.Since this process only occurs very briefly, the medium from the pressure region 11 does not usually pass through the forming sealing gap 5 towards the atmospheric region 12. After overcoming the breakaway torque, the torque between the first sliding ring carrier 31 and the rotating sliding ring 3 immediately drops, so that the sliding surfaces immediately smooth out again.

[0027] Since the same sliding surface deformation occurs on the second sliding surface 40 of the stationary sliding ring 4 during the start-up process to overcome the breakaway torque, the short-term waviness appears on both sliding surfaces and disappears immediately after the breakaway torque is overcome. Therefore, this design of the mechanical seal arrangement offers significant advantages, particularly at very high pressures in the product range 11.

[0028] Furthermore, the transmission elements 60 of the torque device 6 on the stationary sliding ring 4 between the stationary sliding ring 4 and the second sliding ring carrier 41 are designed identically to those on the rotating sliding ring. During the start-up process, a corresponding counter-torque M2 acts between the stationary sliding ring 4 and the second sliding ring carrier 41, since during the start-up process the rotating sliding ring 3, which is in contact with the stationary sliding ring 4, attempts to set the stationary sliding ring 4 into rotation. In this process, the stationary sliding ring 4 is supported on the second sliding ring carrier 41 via the transmission elements 60, and the counter-torque M2 is generated on the stationary sliding ring 4.

[0029] The number of transmission elements 60 on the rotating sliding ring 3 and on the stationary sliding ring 4 is preferably the same.

[0030] The invention offers a solution that addresses a particular problem encountered with mechanical seals, especially at the start of rotation during machine start-up. Specifically, the invention allows the unrestricted use of ceramic sliding rings as both rotating and stationary sliding rings. Prior art has required considerable effort to mitigate this critical situation during start-up of the mechanical seal by employing shrink fits, bandages, or sliding ring materials with low brittleness. Furthermore, the mechanical seal of the invention eliminates the need to design the mechanical seal arrangement in such a way that, when the mechanical seal is stationary, a critical operating state with a defined residual leakage due to a minimal gap between the sliding rings is not required to minimize breakaway torque.

[0031] Furthermore, the invention enables the use of ceramic materials for the stationary and rotating sliding ring without a coating, since the starting torques of the mechanical seal arrangement according to the invention can be significantly reduced. In the prior art, diamond coatings are frequently used to ensure a long service life for the sliding rings in frequent start-stop situations with correspondingly high starting torques. The invention eliminates the need for such expensive diamond coatings or the like.

[0032] Thus, the mechanical seal 1 enables a significant reduction in the breakaway torque of the mechanical seal 2 during a start-up process. The cylindrical transmission elements 60 are preferably made of metal, and the rotating sliding ring 3 and the stationary sliding ring 4 are made of a ceramic material, in particular SiC.

[0033] The Figs. 3 and 4Figure 1 shows a mechanical seal assembly 1 according to a second embodiment of the invention. Identical or functionally equivalent parts are designated with the same reference numerals as in the first embodiment.

[0034] The second embodiment essentially corresponds to the first embodiment, except that, unlike the first embodiment, the transmission elements 70 are designed differently in the second embodiment. In the second embodiment, the transmission elements 70 are designed such that they comprise a first body 71 and a second body 72, as well as a connecting device 73. The first body 71 has a curved first contact surface 71a for contact with the first receiving opening 61 in the first sliding ring carrier 31. The second body 72 has a second arcuate contact surface 72a for contact with the second receiving opening 62 in the rotating sliding ring 3.

[0035] As from Fig. 3As can be seen, the first body 71 has a smaller cross-section than the second body 72. The first body 71 has an elliptical cross-section, and the second body 72 also has an elliptical cross-section. The connecting device 73 comprises a plurality of rods (see figure). Fig. 4 ), which establish a connection between the first body 71 and the second body 72. The rods of the connecting device 73 exhibit greater elasticity than the first body 71 and the second body 72. This ensures that during the start-up process of the mechanical seal assembly, a smooth torque is applied from the first sliding ring carrier 31 to the rotating sliding ring 3. The first and second bodies 71, 72 are rod-shaped components that extend in the axial direction XX of the mechanical seal. The connecting device 73, with its plurality of rods, extends in the radial direction of the mechanical seal assembly.

[0036] What's next? Fig. 3 As can be seen, the radius R2 of the first receiving opening 61 is smaller than the radius R3 of the second receiving opening 62. The cross-sections of the elliptical first and second bodies 71, 72 are adapted to the radii R2 and R3. Thus, during the start-up process, a rolling process occurs between the contact surfaces of the receiving openings 61, 62 and the first and second bodies 71, 72 via a small rotation angle, preferably less than 5°. As in the first embodiment, a plurality of transmission elements 70, preferably all of identical design, are provided along the circumference of the rotating sliding ring 3. Such transmission elements 70 can, of course, also be provided between the stationary sliding ring 4 and the second sliding ring carrier 41. Otherwise, this embodiment corresponds to the first embodiment, so reference can be made to the description given therein. Reference symbol list

[0037] 1 Mechanical seal assembly 2 Mechanical seal 3 Rotating sliding ring 4 Stationary sliding ring 5 Sealing gap 6 Torque device 10 Shaft 11 Product range 12 Atmospheric range 30 Sliding surface 31 First sliding ring carrier 40 Sliding surface 41 Second sliding ring carrier 60 Transmission elements / Rolling elements 61 First receiving opening in the sliding ring carrier 62 Second receiving opening in the sliding ring 70 Transmission elements 71 First body 71a First contact surface 72 Second body 72a Second contact surface 73 Connecting device / Rods A Distance F Force K Force application point M1 Torque on the rotating sliding ring M2 Counter-torque on the stationary sliding ring R1 First radius of the rolling elements R2 Second radius of the first receiving opening R3 Third radius of the second receiving opening T Tangent α Angle

Claims

1. Mechanical seal arrangement, comprising: - a mechanical seal (2) having a rotating slide ring (3) having a first sliding surface (30) and a stationary slide ring (4) having a second sliding surface (40), wherein a sealing gap (5) is defined between the sliding surfaces (30, 40), - a torque device (6) for transmitting a torque between one of the slide rings and a slide ring carrier (31, 41), - wherein the torque device (6) comprises a plurality of transmission elements (60, 70) which are configured for transmitting torque between the slide ring carrier (31, 41) and the slide ring such that a total torque is divided over the plurality of transmission elements (60, 70), - wherein the slide ring carrier (31, 41) comprises first receiving openings (61) having a cross-section that is curved and the slide ring comprises second receiving openings (62) which have a cross-section that is curved, and - wherein the transmission elements (60, 70) are arranged in the first and second receiving opening (61, 62), characterized in that the transmission elements (60) are rolling elements which are configured for performing a rolling process between the slide ring carrier (31, 41) and the slide ring in the case of torque transmission.

2. Mechanical seal arrangement according to claim 1, wherein the rolling bodies are cylinders.

3. Mechanical seal arrangement according to claim 1 or 2, wherein a first radius R1 of the cylinder is smaller than a second radius R2 of the first receiving opening (61) in the slide ring carrier, and / or wherein the first radius R1 of the cylinder is smaller than a third radius R3 of the second receiving opening (62) in the slide ring.

4. Mechanical seal arrangement according to claim 3, wherein the second radius R2 is the same size as the third radius R3.

5. Mechanical seal arrangement comprising: - a mechanical seal (2) having a rotating slide ring (3) having a first sliding surface (30) and a stationary slide ring (4) having a second sliding surface (40), wherein a sealing gap (5) is defined between the sliding surfaces (30, 40), - a torque device (6) for transmitting a torque between one of the slide rings and a slide ring carrier (31, 41), - wherein the torque device (6) comprises a plurality of transmission elements (60, 70) which are configured for transmitting torque between the slide ring carrier (31, 41) and the slide ring such that a total torque is divided over the plurality of transmission elements (60, 70), - wherein the slide ring carrier (31, 41) comprises first receiving openings (61) having a cross-section that is curved and the slide ring comprises second receiving openings (62) which have a cross-section that is curved, and - wherein the transmission elements (60, 70) are arranged in the first and second receiving opening (61, 62), characterized in that the transmission elements (70) comprise a first body (71), a second body (72) and a connection device (73) which connects the first body (71) to the second body (72), wherein the first body (71) comprises a curved first contact surface for contact to the first receiving opening (61) in the slide ring carrier (31, 41) and the second body (72) comprises a second curved contact surface for contact with the second receiving opening (62) in the slide ring.

6. Mechanical seal arrangement according to claim 5, wherein the connection device comprises one or more rods (73) extending substantially in the radial direction and / or a framework-like connection.

7. Mechanical seal arrangement according to claim 5 or 6, wherein the connection device has greater elasticity than the first body (71) and the second body (72).

8. Mechanical seal arrangement according to any one of claims 5 to 7, wherein the first body (71) and / or the second body (72) is a rod-shaped component having an elliptical cross-section.

9. Mechanical seal arrangement according to any one of the preceding claims, wherein a torque device (6) is arranged both on the rotating slide ring (3) and on the stationary slide ring (4) for transmitting torque from the slide rings to the slide ring carrier (31, 41).

10. Mechanical seal arrangement according to any one of the preceding claims, wherein the torque device (6) is arranged in the first receiving opening (61) and the second receiving opening (62) in such a way that a force introduction point K is at a spacing A from an edge of the first and second receiving opening (61, 62).

11. Mechanical seal arrangement according to any one of the preceding claims, wherein the rotating slide ring (3) and / or the stationary slide ring (4) are produced from ceramic material, and / or wherein the rotating slide ring and the stationary slide ring (4) do not have any coating on the sliding surface (30, 40).

12. Mechanical seal arrangement according to any one of the preceding claims, - wherein a line contact is present between the transmission elements (60, 70) and the first receiving opening (61) and the second receiving opening (62).

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