SLIDING RING OF A SLIDING RING SEAL AND METHOD FOR ITS MANUFACTURING

Description

[0001] The present invention relates to a sliding ring of a mechanical seal, a mechanical seal arrangement and a method for producing the sliding ring.

[0002] Mechanical seal rings are known in various designs from the prior art. Recently, sensors have increasingly been arranged on a sliding surface of the seal ring to monitor, for example, its wear. This gives rise to a problem in that the sensors located on the sliding surface must be electrically contacted. Since the sensors are located on the sliding surface, it is necessary to have an electrical through-hole connection through the seal ring. Since a very brittle ceramic is often used as the material for the seal ring, holes or similar holes that have to be drilled into the seal ring to enable electrical contact are particularly dangerous in that they pose the risk of invisible damage and cracks in the seal ring.Furthermore, seal rings are often coated on their sliding surfaces, for example with a diamond coating. However, bores in the seal ring that extend to the sliding surface, even if filled with material, are very disadvantageous in this case, as the coating often detaches at the edges of the bores. Since a coating is usually applied as the last step in the manufacture of the seal ring, very high process temperatures of up to 900°C occur with a diamond coating, for example. This creates thermal problems for any low-melting metals present in the seal ring for electrical contact, as the melting points of such metals are significantly lower than the coating temperatures.

[0003] EP3770471A1 discloses a sintered ceramic sliding ring made of an electrically conductive ceramic material.

[0004] It is therefore an object of the present invention to provide a sliding ring, a mechanical seal arrangement and a method for producing a sliding ring, which enable a reliable electrical contacting of sensors on a sliding surface of the sliding ring with a simple structure and simple, cost-effective manufacture and implementation.

[0005] This object is achieved by a sliding ring having the features of claim 1, a mechanical seal arrangement having the features of claim 12, and a method having the features of claim 13. The subclaims each show preferred developments of the invention.

[0006] The sliding ring of a mechanical seal arrangement according to the invention with the features of claim 1 has the advantage that simplified and reliable electrical contact is possible through a sliding ring. This makes it possible, in particular, to electrically contact sensors arranged on or near a sliding surface of the sliding ring or in the sliding ring. However, it is also possible, for example, for an electrical circuit to be passed through the sliding ring, which can be used, for example, to measure wear if the electrical circuit is arranged in such a way that, in the event of wear on the sliding surface of the sliding ring, the electrical circuit is interrupted when wear is sufficiently advanced. The sliding ring can be made from an electrically non-conductive, ceramic material, which is advantageous with regard to its suitability as a sliding ring material.This is achieved according to the invention in that the sliding ring has a sintered, ceramic ring with a sliding surface, wherein the ceramic ring is made of an electrically non-conductive ceramic material. Furthermore, an electrical contact body is provided, which is arranged in the ring for electrical contact. The electrical contact body is made of a sintered ceramic material that is electrically conductive. The electrical contact body is arranged in a recess in the ring and fills the recess at least partially, preferably completely. Thus, a ceramic sliding ring can be provided which, due to the introduction of the electrical contact body, is electrically conductive only in the region of the electrical contact body.Since both the ring and the contact body are made of a ceramic material, there are considerable advantages in operation compared, for example, with a sliding ring in which a metallic material is arranged as an electrical conductor, since the heat generated during operation of the mechanical seal arrangement in the sliding ring according to the invention leads to a very uniform volume change in the ring and in the electrical contact body.

[0007] Particularly preferably, a plurality of chemical bonds produced by sintering are formed between the electrical contact body and the ring. This ensures, on the one hand, secure fixation of the contact body in the ring and, on the other hand, thermally induced volume changes of the ring and contact body are carried out particularly uniformly. It should be noted that the contact body and the ring can be sintered together in a single step, or alternatively, the ring can be pre-sintered, followed by the contact body material being introduced into the recess, and then, in a second sintering step, the pre-sintered ring and the contact body material are re-sintered.

[0008] The recess in the ring is preferably a through-hole. The through-hole can run from a rear side to the sliding surface, in particular in a straight line, or alternatively from an inner circumferential side or an outer circumferential side to the sliding surface. This allows electrical contact of the sliding ring on the circumferential sides, which is advantageous in some designs of mechanical seal arrangements.

[0009] Particularly preferably, the contact body has a blind hole filled with an electrically conductive metal material. The blind hole is arranged on an outlet side of the contact body, for example, on a rear side of the sliding ring. This enables simple electrical contacting of the electrical contact area of ​​the sliding ring. For example, an electrical line to a measuring device or a computer or the like can be attached to the electrically conductive metal material by soldering or welding without damaging the ceramic material of the sliding ring. This also prevents the introduction of undesired voltages into the sliding ring due to electrical contacting of the contact area.

[0010] The electrically conductive metal material is preferably a metal pin, which is inserted into the blind hole in the electrical contact body by means of a press connection. This allows the metal pin to be easily and securely fixed in the electrical contact body.

[0011] Particularly preferably, the metal region on the exit side of the contact body forms an electrical connection for the electrical contact body, to which an electrical line can be easily attached by soldering or welding.

[0012] More preferably, the sliding ring comprises a sensor arranged on the sliding ring, which is electrically connected to the electrical contact body. This allows the sensor to be electrically contacted in a simple and reliable manner, while the sliding ring can still be made of a ceramic material. The sensor is preferably arranged on a sliding surface of the sliding ring. A recess can be provided in the sliding surface of the sliding ring, in which the sensor is arranged. The electrical contact body can then extend to the recess and electrically contact the sensor.

[0013] Preferably, the sliding ring is a stationary sliding ring of the mechanical seal assembly and comprises two electrical contact bodies in the ring of the sliding ring to enable electrical contact with the sensor via a closed circuit. The first contact body is an electrical supply line, and the second contact body is an electrical return line.

[0014] According to a further preferred embodiment of the invention, the sliding ring has a coating. The coating can be, for example, a diamond coating or a titanium nitride coating. Coated sliding rings are preferred because the coating on the sliding surface of the sliding ring can extend the service life of the sliding ring by reducing wear. However, one problem with coating the sliding surface of a sliding ring is that this typically requires very high process temperatures, for example, up to 900°C for a diamond coating. However, metals intended for electrical contact in a sliding ring melt at such high temperatures of approximately 900°C.However, this has not yet made it possible to equip coated seal rings with a sensor, especially a wear sensor, because electrical contacting of the sensor is not possible using conventional contacting methods. However, subsequently introducing an electrical connection, for example, by drilling a hole in the ceramic ring after the coating has been applied, is very difficult and costly, and there is always the risk of cracks in the ceramic seal ring or damage to the coating. As a result, the reject rate in the production of such coated ceramic seal rings with electrical leads is very high and generally uneconomical.

[0015] The ceramic ring of the sliding ring is preferably made of SiC, which is an electrically non-conductive material, i.e., it has an electrical conductivity of ≤ 10 -8 < S / m at 20°C. The material used for the electrical contact body is preferably Si-SiC, i.e., silicon-infiltrated SiC, or doped SiC, which has electrical conductivity, or SiC-C-Si, i.e., SiC infiltrated with carbon and silicon.

[0016] Furthermore, the present invention relates to a mechanical seal assembly comprising a sliding ring according to the invention. The sliding ring according to the invention is preferably used as the stationary sliding ring of the mechanical seal assembly. The mechanical seal assembly particularly preferably comprises a sensor on the stationary sliding ring, which is electrically connected to a measuring device via the electrical contact body. The sensor is, in particular, a wear sensor.

[0017] Furthermore, the present invention relates to a method for producing a sliding ring, in particular a stationary sliding ring, of a mechanical seal assembly. The method comprises the following steps: Producing an annular green compact from an electrically non-conductive ceramic material, introducing a recess into the green compact, filling the recess in the green compact with an electrically conductive ceramic material, and sintering the green compact with the filled recess.

[0018] The method according to the invention thus makes it possible to produce a ceramic seal ring of a mechanical seal assembly that is electrically non-conductive, yet has an electrically conductive contact body formed by the sintered, electrically conductive ceramic material located in the recess. This achieves the advantages described above for the seal ring.

[0019] Preferably, in the method according to the invention, after the recess has been formed in the green compact, the green compact is pre-sintered. Subsequently, the electrically conductive ceramic material is introduced into the recess, and a second sintering (post-sintering) is performed to obtain the ceramic sliding ring with a ceramic electrical contact body. Thus, the sliding ring can be obtained by sintering in two steps.

[0020] Preferably, after sintering the sliding ring, a coating, in particular a diamond coating, is applied to a sliding surface of the sliding ring. Further preferably, after sintering, a blind hole is formed in the electrical contact body in the sliding ring, which is filled with an electrically conductive metal material, preferably in the form of a metal pin pressed into the recess.

[0021] Preferred embodiments of the invention will be described in detail below with reference to the accompanying drawings. In the drawing: Fig. 1 is a schematic sectional view of a mechanical seal arrangement with a sliding ring according to the invention according to a first embodiment of the invention, Fig. 2 is a schematic sectional view of the sliding ring according to the invention of Fig. 1 , Fig. 3 is a schematic sectional view of a sliding ring according to a second embodiment of the invention, and Fig. 4 is a schematic sectional view of a sliding ring according to a third embodiment of the invention.

[0022] The following is based on the Figures 1 and 2 a mechanical seal arrangement 1 according to a first preferred embodiment of the invention is described in detail.

[0023] As from Fig. 1As can be seen, the mechanical seal arrangement 1 comprises a mechanical seal 2 with a rotating seal ring 3 and a stationary seal ring 4. The rotating seal ring 3 has a first sliding surface 3a and the stationary seal ring 4 has a second sliding surface 4a.

[0024] A sealing gap 5 is defined between the two sliding surfaces 3a, 4a of the seal rings 3, 4. The mechanical seal assembly 1 seals an area 18, in which a product to be sealed is present, from an atmospheric area 19 on a shaft 14. The rotating seal ring 3 is connected to the shaft 14 in a rotationally fixed manner by means of a seal ring carrier 16 and a screw 17.

[0025] Furthermore, a preloading element 15 is provided, which preloads the rotating slide ring 3 in an axial direction of a central axis XX against the stationary slide ring 4.

[0026] The stationary seal ring 4 is sealed to a stationary housing component 20 by means of a first O-ring 21. The rotating seal ring 3 is sealed to the shaft 14 by means of a second O-ring 22 on its inner circumference.

[0027] The mechanical seal assembly 1 further comprises a measuring device 6, which is particularly designed to measure wear of the stationary seal ring 4 on its sliding surface 4a. The measuring device 6 is connected to a sensor 7. The sensor 7 is arranged on the sliding surface 4a of the stationary seal ring 4.

[0028] The sensor 7 is arranged in a recess 43 in the sliding surface and is preferably a wear sensor.

[0029] For this purpose, an electrical contact of the sensor 7 on the sliding surface 4a must be provided, which is shown in detail in Fig. 2 As can be seen from Fig. 2As can be seen, the stationary sliding ring 4 has a sintered, ceramic ring 41 made of an electrically non-conductive ceramic material, in particular SiC. Furthermore, two identically constructed electrical contact bodies 42 are arranged in the ring 41, which are made of a sintered ceramic material that exhibits electrical conductivity, in particular silicon-infiltrated SiC (Si-SiC).

[0030] As from Fig. 2 As can be seen, the contact areas 42 extend from a rear side 4b to the sliding surface 4a. A coating 9 is provided on the sliding surface 4a. The electrical contact bodies 42 are arranged in recesses 40 formed in the ring 41 and extend in a straight line through the sliding ring 4.

[0031] The electrical contact bodies 42 each have an electrical connection 13 for an electrical line 8 on an exit side on the rear side 4b of the sliding ring 4. The electrical connection 13 is formed such that a blind hole 10 is provided in the electrical contact body 42, which is open to the rear side 4b of the stationary sliding ring 4 and which is filled with a metal material in the form of a metal pin 11. A press connection 12 is formed between the metal pin 11 and the recess 10.

[0032] In other words, the electrical contact body 42 has a blind hole 10 on the side facing the rear of the sliding ring 4, which is filled with the metal pin 11, so that electrical contacting of the electrical contact body 42 can be effected via the metal pin 11. As shown in Figure 1As shown, the two electrical contact bodies 42 are electrically connected to the measuring device 6 by the electrical lines 8 and thus the sensor 7 is also electrically connected to the measuring device 6.

[0033] The stationary sliding ring 4 made of ceramic material can be manufactured in such a way that, in a first step, an annular green compact is provided corresponding to the desired geometric shape of the stationary sliding ring 4 made of an electrically non-conductive ceramic material, e.g., SiC. The recesses 40 for the electrical contact bodies 42 are then introduced into the green compact. In a next step, the recesses are filled with an electrically conductive, ceramic material, e.g., Si-SiC, which then forms the electrical contact bodies 42 in the finished sliding ring. In a next step, the green compact is sintered. In this case, chemical bonds are produced, in particular by sintering, between the material of the ring and the material of the contact bodies. As a result, the electrically conductive region in the form of the electrical contact bodies 42 is integrated into the sliding ring.

[0034] If a sensor 7 is to be provided, for example, on the sliding surface of the sliding ring, a correspondingly designed recess or the like is preferably provided in the sliding surface, in which the sensor 7 will later be accommodated. The electrical contact areas 42 then expediently extend to the recess in order to later electrically contact the sensor.

[0035] Since the thermal expansion of the ceramics of the ring 41 and the electrical contact body 42 is essentially the same, there is no component weakening due to thermal expansion, as would be the case when using a metallic material for electrical contact. Furthermore, this also eliminates temperature-dependent restrictions on the choice of coating 9. In particular, a diamond coating, which must be applied at temperatures of approximately 900°C, can be provided.

[0036] Furthermore, the atomic bonds during the sintering step between the material of the ring 41 and the material of the electrical contact bodies 42 result in flush finishes, particularly at the sliding surface, so that the sliding ring has excellent flatness and, in particular, there is also an edgeless transition between the ring material and the material of the electrical contact area.

[0037] The atomic bond between the electrically non-conductive ceramic material of the ring 41 and the electrically conductive, ceramic material of the contact body 42 also results in significantly improved emergency running properties, in particular with regard to a possible emergency running duration, since on the sliding surface 4a, for example after wear of a coating 9, there is still a flat surface, in particular at the transition between the two materials, which is edge-free and can be used as a sliding surface for emergency running.

[0038] Thus, a stationary sliding ring 4 can be provided, which, for example, has a wear sensor 7 on the sliding surface and a coating 9 in the form of a diamond coating. The sensor contact is integrated into the ring and ensured by a lubricious, ceramic material. Using the metal pin 11 in the electrically conductive material, a particularly simple thermal electrical contact can also be made by welding or soldering directly on the sliding ring, without damaging the sliding ring.

[0039] Figure 3 shows a slide ring 4 of a mechanical seal assembly according to a second embodiment of the invention. Identical or functionally identical parts are designated by the same reference numerals as in the first embodiment.

[0040] In contrast to the first embodiment, the sliding ring of the second embodiment has no coating. A sensor 7 is arranged directly on the sliding surface 4a of the stationary sliding ring 4. Electrical contact with the sensor 7 is made on a rear side of the sensor by an electrical contact body 42. This is designed the same as in the first embodiment and is made of an electrically conductive ceramic material. A metal pin 11 is attached to the rear side 4b, i.e., the exit side of the electrical contact body 42, for easy electrical contact. Otherwise, the embodiment corresponds to the previous embodiment, so reference can be made to the description given there.

[0041] Figure 4shows a sliding ring 4 according to a third embodiment of the invention. Identical or functionally identical parts are designated by the sliding reference numerals as in the previous embodiments.

[0042] As from Figure 4As is immediately apparent, in the third exemplary embodiment the electrical contact is provided on an outer circumferential side 4d instead of on the rear side 4b. The recess 40 thus forms a 90° angle in the ring 41. This can be provided, for example, by making two bores in the ceramic ring 41. It should be noted that electrical contact on an inner circumferential side 4c would also be possible in the same way. If two electrical contacts are provided, it would also be conceivable for one electrical contact to be formed on the outer circumferential side 4d and one electrical contact on the inner circumferential side 4c. Furthermore, a combination with contact on the rear side 4b of the stationary slide ring 4 and one of the circumferential sides 4c, 4d would of course also be conceivable. Otherwise, this exemplary embodiment corresponds to the previous exemplary embodiments, so that reference can also be made to the given description.

[0043] In addition to the above written description of the invention, for its supplementary disclosure, reference is hereby explicitly made to the graphic representation of the invention in the Fig. 1 to 4 Reference is made. List of reference symbols

[0044] 1 Mechanical seal arrangement 2 Mechanical seal 3 Rotating seal ring 3a First sliding surface 4 Stationary seal ring 4a Second sliding surface 4b Rear side 4c Inner peripheral side 4d Outer peripheral side 5 Sealing gap 6 Measuring device 7 Sensor 8 Electrical line 9 Coating 10 Blind hole in the contact body 11 Metal pin 12 Press connection 13 Electrical connection 14 Shaft 15 Preloading element 16 Sealing ring support 17 Screw 18 Area in which the product to be sealed is present 19 Atmosphere area 20 Housing component 21 First O-ring 22 Second O-ring 40 Recess 41 Electrically non-conductive ceramic ring 42 Electrically conductive contact body 43 Recess in the sliding surface X-X Central axis

Claims

1. Slide ring of a mechanical seal assembly, comprising - a sintered, ceramic ring (41) having a slide surface (4a), which ring is made of an electrically non-conductive ceramic material, and - an electrical contact body (42), which is configured for electrical contacting and is arranged in the ring (41), - wherein the electrical contact body (42) is made of a sintered ceramic material which is electrically conductive, and - wherein the electrical contact body (42) is arranged in a recess (40) in the ring (41) and fills the recess (40).

2. Mechanical seal according to claim 1, wherein chemical bonds produced by sintering are formed between the electrical contact body (42) and the ring (41).

3. Slide ring according to any of the preceding claims, wherein the recess (40) is a through-recess which extends from a rear surface (4b) to the slide surface (4a) or extend from an inner circumferential surface (4c) or an outer circumferential surface (4d) to the slide surface (4a).

4. Slide ring according to any of the preceding claims, wherein the contact body (42) comprises a blind hole (10) on an exit side of the contact body which is facing away from the slide surface and is filled with an electrically conductive metal material.

5. Slide ring according to claim 4, wherein the electrically conductive metal material is a metal pin (11), wherein a press fit (12) is formed between the metal pin (11) and the blind hole (10).

6. Slide ring according to any of claims 4 or 5, wherein an electrical line (8) is electrically connected to the electrical contact body (42) at a terminal (13) formed by an exposed region of the electrical metal material.

7. Slide ring according to any of the preceding claims, further comprising a sensor (7) which is arranged on the slide ring and is electrically connected to the electrical contact body (42).

8. Slide ring according to claim 7, wherein the sensor is arranged on the slide surface of the slide ring.

9. Slide ring according to claim 7 or 8, wherein the slide ring is a stationary slide ring of the mechanical seal assembly and two contact bodies (42) are provided in the ring (41) for electrically contacting the sensor (7).

10. Slide ring according to any of the preceding claims, wherein the slide surface (4a) of the ring (41) is coated with a coating (9).

11. Slide ring according to any of the preceding claims, wherein the ring (41) is made of SiC and the electrical contact body (42) is made of Si-SiC or doped SiC or SiC-C-Si.

12. Mechanical seal assembly, comprising a stationary slide ring (4) in accordance with any one of the preceding claims and a measuring apparatus (6), which is electrically connected to the contact body (42) of the slide ring (4).

13. Method for producing a slide ring, comprising the steps of: - producing an annular green body from an electrically non-conductive ceramic material, - making a recess (40) in the green body, - filling the recess (40) with an electrically conductive, ceramic material, and - sintering the green body and the introduced ceramic material such that a ceramic slide ring comprising an electrically non-conductive ceramic ring (41) and an electrically conductive, ceramic contact body (42) is produced.

14. Method according to claim 13, wherein after making the recess in the green body, the green body is pre-sintered and the electrically conductive ceramic material is introduced into the recess (40) after the pre-sintering, and subsequently the pre-sintered green body and the ceramic material introduced into the recess are re-sintered.

15. Method according to claim 13 or 14, wherein a coating (9) is applied to the slide surface (4a) of the slide ring after the sintering.

16. Method according to any of claims 13 to 15, wherein after the sintering, a blind hole is made in the contact body (42) made of the electrically conductive ceramic material and the blind hole is filled with an electrically conductive metal in order to provide the option of electrical contacting at the introduced metal.