SLIDING RING WITH WEAR MEASURING DEVICE AND SLIDING RING SEAL ASSOCIATION WITH SUCH A SLIDING RING

Description

[0001] The invention relates to a stationary sliding ring of a mechanical seal arrangement with a wear measuring device and to a mechanical seal arrangement with such a stationary sliding ring.

[0002] Mechanical seals are known in various designs from the prior art. Although mechanical seals generally operate without contact, as a gas or liquid is present in the sealing gap between the seal rings, contact occurs at the sliding surfaces when a device sealed with a mechanical seal is started up and shut down. External factors can also cause contact at the sliding surfaces during operation, leading to wear and potentially necessitating replacement. Since, in the worst case, wear can cause the mechanical seal to fail, resulting in the leakage of the sealed medium, worn seal rings should ideally be replaced before complete failure. However, replacement should not be premature, as seal rings are very expensive components.JP H02176270 A discloses a mechanical seal arrangement with a wear measuring unit which is guided from the rear through a bore to the sliding surface of the stationary sliding ring.

[0003] Therefore, the object of the present invention is to provide a sliding ring and a sliding ring seal arrangement which, with a simple design and simple, cost-effective manufacturability, have a wear measuring device in order to detect wear of the sliding ring with high accuracy.

[0004] This problem is solved by a stationary sliding ring of a mechanical seal arrangement having the features of claim 1 and a mechanical seal arrangement having the features of claim 11. The dependent claims describe preferred embodiments of the invention.

[0005] The stationary sliding ring of a mechanical seal arrangement with the features of claim 1 has the advantage that a reliable detection of wear of the stationary

[0006] The stationary sliding ring can be measured on its sliding surface. In particular, current wear can be detected in a simple and reliable manner. Thus, the stationary sliding ring according to the invention can not only detect when a defined wear limit is reached, but it is also possible to continuously monitor the existing wear over the service life of the stationary sliding ring until the wear limit is reached. Despite this, the stationary sliding ring has a simple and cost-effective design. This is achieved according to the invention by the stationary sliding ring comprising a base body with a sliding surface and a wear measuring device. The wear measuring device is arranged on the base body.The wear measuring device is designed to detect the current wear of the stationary sliding ring on its sliding surface based on a change in an electrical parameter. The wear measuring device comprises an electrical voltage source, a measuring area on the sliding surface of the stationary sliding ring, an electrical supply line connecting the voltage source to the measuring area, and an electrical return line connecting the measuring area to the voltage source. The measuring area of ​​the wear measuring device is located in a recess in the sliding surface of the stationary sliding ring. The measuring area thus completes the electrical circuit from the voltage source via the supply line and the return line. If wear occurs on the sliding surface, the measuring area also wears accordingly. This, however, changes, for example, the wear pattern.The electrical resistance at the measuring range decreases because the measuring range located in the recess becomes thinner due to wear. The change in resistance is essentially proportional to the amount of wear. Therefore, by measuring the change in the electrical resistance of the circuit, the wear occurring on the sliding surface of the stationary sliding ring can be determined very precisely. Changes in other electrical quantities can also be measured in this way.

[0007] Preferably, the recess in the sliding surface of the stationary sliding ring is completely filled with an electrically conductive material. The outer surface of the electrically conductive material in the recess is flush with the sliding surface of the base body of the stationary sliding ring. This ensures that wear, starting from a new sliding ring, can be continuously monitored throughout the entire service life of the sliding ring.

[0008] The electrically conductive material in the recess is preferably titanium nitride. More preferably, the stationary sliding ring is made of a carbide material, in particular SiC or WC, wherein the carbide material is adapted such that it has no or only minimal electrical conductivity.

[0009] Preferably, the depth of the recess is selected such that when wear occurs down to the bottom of the recess, a wear limit of the stationary sliding ring is reached. Thus, when the material in the recess has been completely worn away, the electrical circuit of the wear measuring device is interrupted, which is an easily detectable indicator of reaching a predetermined wear limit of the stationary sliding ring.

[0010] In order to have the most uniform wear possible in the measuring area in the recess, the recess is preferably designed as an arc-shaped groove.

[0011] Preferably, the electrical supply line is routed through a first bore in the base body of the stationary sliding ring to the measuring area, and / or the electrical return line is routed through a second bore in the base body of the stationary sliding ring. The first bore and the second bore are preferably arranged on the same radius.

[0012] Particularly preferred is an electrically conductive filler material arranged in the first bore and / or the second bore in the base body, wherein the filler material completely fills the first and / or second bore. Silver is preferably used as the electrically conductive filler material.

[0013] Preferably, the width of the recess is greater than or equal to the diameter of the first and / or second bore. Preferably, the diameter of the first and second bores is the same; in particular, the diameter of the first and second bores is 1 mm ±10%.

[0014] The arc-shaped depression is preferably arranged on a circumferential section of the sliding surface that is central in the radial direction.

[0015] To prevent the stationary sliding ring from exhibiting imbalance, waviness, or any other type of geometric deformation due to the wear measuring device, a second wear measuring device is preferably arranged on the base body, positioned at 180° to the first. Alternatively, three or four wear measuring devices at equal circumferential intervals can be provided on the stationary sliding ring. All measuring devices are preferably identical.

[0016] Furthermore, the present invention relates to a mechanical seal assembly comprising a mechanical seal with a rotating sliding ring and a stationary sliding ring according to the invention. The sliding rings have a sealing gap between their sliding surfaces, and the mechanical seal assembly further comprises an automated measuring unit configured to detect wear on the sliding surface of the stationary sliding ring. The wear is determined by measuring electrical parameters, in particular an electrical resistance, of the electrical circuit integrated into the stationary sliding ring and, based on a comparison with stored reference data, infers the wear of the stationary sliding ring. The stored reference data can be data acquired on a test bench and / or data acquired during the operation of mechanical seals.In particular, the stored comparison data can be continuously updated by adding new data from the operation of mechanical seals.

[0017] Preferably, the automated measuring unit continuously or at shorter intervals, for example every half hour or hour, records the electrical quantities used to determine wear, in particular the electrical resistance, during normal operation of the mechanical seal assembly.

[0018] Thus, the present invention allows the wear of the stationary sliding ring to be determined at any desired time. Based on the wear of the stationary sliding ring, conclusions can then be drawn about the wear of the entire mechanical seal, and, if necessary, the sliding rings can be replaced. This allows a high degree of certainty to prevent a sudden failure of the mechanical seal, thus preventing a sudden failure of the mechanical seal and the potential leakage of the hazardous medium, particularly when sealing environmentally hazardous media. Preferably, the replacement of the sliding rings is initiated before the defined maximum wear limit is reached, so that the replacement of the sliding rings can be planned even by a user of the mechanical seal assembly, for example, in a large plant.

[0019] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows: Fig. 1 a schematic sectional view of a mechanical seal arrangement with a stationary sliding ring according to a first embodiment of the present invention, Fig. 2 a schematic, perspective view of the stationary sliding ring of Fig. 1 , Fig. 3 a schematic sectional view along line III-III of Fig. 2 of the stationary sliding ring, Fig. 4 a schematic, enlarged cross-sectional view along line IV-IV of Fig. 3 of the stationary sliding ring, and Fig. 5 a schematic, perspective view of a stationary sliding ring according to a second embodiment of the invention.

[0020] The following refers to the Figures 1 to 4A mechanical seal arrangement 1 with a stationary sliding ring 4 according to a first embodiment of the invention is described in detail.

[0021] As from Fig. 1 As can be seen, the mechanical seal arrangement 1 comprises a mechanical seal 2 with a rotating sliding ring 3 and the stationary sliding ring 4. A sealing gap 5 is defined between a sliding surface 30 of the rotating sliding ring 3 and a sliding surface 40 of the stationary sliding ring 4.

[0022] The mechanical seal 2 seals a product area 12 from an atmospheric area 13 on a shaft 11. The rotating sliding ring 3 is connected to the shaft 11 by means of a sliding ring carrier 31.

[0023] The stationary sliding ring 4 is arranged on a stationary housing 14.

[0024] The stationary sliding ring 4 is detailed from the Figures 2 to 4The stationary sliding ring 4 has a base body 41 on which the sliding surface 40, directed towards the rotating sliding ring 3, is formed.

[0025] Furthermore, the stationary sliding ring 4 includes a wear measuring device 6. The wear measuring device 6 is arranged on the base body 41 and is configured to detect any current wear of the stationary sliding ring 4 of the mechanical seal 2. The wear is detected at the sliding surface 40 of the stationary sliding ring 4.

[0026] The wear measuring device 6 comprises an electrical voltage source 60, a measuring range 6a on the sliding surface 40 of the stationary sliding ring, an electrical supply line 61, and an electrical return line 62. The electrical supply line 61 connects the voltage source 60 to the measuring range 6a. The electrical return line 62 connects the measuring range 6a to the voltage source 60.

[0027] Thus, an electrical circuit is integrated into the stationary sliding ring 4, with the measuring range 6a being arranged on the sliding surface 40.

[0028] As detailed from the Figures 3 and 4 As can be seen, there is an arc-shaped depression 42 in the sliding surface 40 (cf. Fig. 2 ) formed. The arc-shaped recess 42 is completely filled with an electrically conductive material 9, in particular titanium nitride. One surface of the measuring area 6a is planar to the sliding surface 40 of the stationary sliding ring 4, as shown in Fig. 3 depicted.

[0029] What's next? Fig. 3 As can be seen, a first bore 43 and a second bore 44 are formed in the base body 41 of the stationary sliding ring 4. The first and second bores 43, 44 are designed such that one bore is arranged at each end region of the arc-shaped recess 42 (see Figure 4). Fig. 3The first and second bores 43, 44 extend completely through the base body 41 to a rear surface 40a. The two bores 43, 44 extend straight through the base body 41 parallel to an axial direction XX of the mechanical seal assembly 1.

[0030] As especially from Fig. 3 As can be further seen, the first bore 43 is completely filled with a first conductive filler material 7. The first electrically conductive filler material 7 is connected to the electrical voltage source 60 at the rear 40a of the stationary sliding ring 4 by means of a conductor section 61a. In the same way, the second bore 44 is also filled with a second electrically conductive filler material 8, which is connected to the electrical voltage source 60 by means of a conductor section 62a of the return conductor 62.

[0031] The first and second filling material 7, 8 is preferably the same material, in particular silver. Silver has the advantage of very good electrical conductivity and can be introduced and hardened relatively easily into the bores 43, 44. Furthermore, simple connection of the conductor sections 61a, 62a of the supply and return lines of the wear measuring device 6 can be ensured.

[0032] The first and second bores 43, 44 are preferably identical and have a diameter D. The arc-shaped recess 42 has, as shown in particular, Fig. 4 As can be seen, the bores 43 and 44 have a width B that is larger than their diameter D. The recess 42 has a depth T of at most 10 µm, preferably at most 5 µm. The diameter D of the first and second bores is preferably 1 mm.

[0033] The depth T of the recess 42 is chosen such that when a bottom 45 of the recess 42 is reached, maximum wear of the sliding surface 40 of the stationary sliding ring 4 is achieved.

[0034] The material of the stationary sliding ring 4 is preferably an electrically non-conductive ceramic. It should be noted that a material with significantly lower electrical conductivity than the filling materials 7, 8 of the wear measuring device 6 can also be used for the stationary sliding ring 4. Preferably, a silicon carbide-containing material is used for the stationary sliding ring.

[0035] The material 9 in the recess 42 is preferably introduced into the recess 42 by means of a coating process, for example a PVD process. Since this often also results in partial coating of areas of the sliding surface 40 that lie around the recess 42, a surface treatment of the sliding surface 40 is carried out in a further step in order to remove this coating that protrudes beyond the recess 42.

[0036] Thus, the wear measuring device 6 is now integrated into the stationary sliding ring 4, which, when a voltage is applied, exhibits an initial resistance value as an electrical parameter in its new state. After the installation of the mechanical seal 2 for sealing against the shaft 11, wear occurs during operation on the sliding surfaces 30, 40 of the sliding rings 3, 4. However, wear also occurs on the material 9 located in the recess 42. This changes the electrical resistance of the circuit of the wear measuring device 6, since material removal from the material 9 leads to a reduced cross-section at the measuring area 6a.

[0037] It has now been established that there is a clear correlation between the changing resistance at measuring range 6a and the wear at the measuring range caused by the removal of material 9 from the surface of the measuring range. This can now be used to determine the wear of the sliding surface 40 of the stationary sliding ring 4. The smaller the cross-section of material 9 in the recess 42 becomes due to increasing wear on the sliding surface 40, the higher the resistance value of the electrical circuit of the wear measuring device 6.

[0038] By means of an automated measuring unit 10 (see Fig. 1The device, which is designed to determine the wear on the sliding surface 40 of the stationary sliding ring 4, can thus be used to determine the wear of the sliding surface 40 at any given time by simply applying a voltage to the circuit integrated into the stationary sliding ring 4. It is possible for the voltage to be applied continuously, or alternatively, for the measurement to be taken at intervals, for example, hourly, daily, or at any other interval that depends on the operating conditions of the mechanical seal 2.

[0039] Thus, according to the invention, a means is provided to determine wear on the sliding surface 40 of the stationary sliding ring 4 with the highest degree of certainty. It is also possible to infer wear on the rotating sliding ring 3 from the determined wear on the sliding surface 40 of the stationary sliding ring 4. This allows maintenance and, for example, replacement of the sliding rings to be planned early, preventing a complete failure due to wear and tear of the mechanical seal 2. As a result, maintenance of the mechanical seal can be planned for the user and then carried out at the most convenient time.

[0040] The depth T of the recess 42, and thus the cross-section of the material 9 at the measuring area 6a, is preferably selected such that the depth T corresponds to the maximum permissible wear on the sliding surface 40 of the stationary sliding ring 4. Therefore, when wear has progressed to the point that the material 9 in the recess 42 is completely worn down to the bottom 45, the circuit is interrupted, thus providing a clear indication that the maximum wear limit of the stationary sliding ring 4 has been reached.

[0041] Fig. 5Figure 1 shows a stationary sliding ring 4 of a mechanical seal arrangement 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. In contrast to the first embodiment, the second embodiment provides a first wear measuring device 6 and a second wear measuring device 6'. As shown in Figure 2, the second embodiment provides a first wear measuring device 6 and a second wear measuring device 6'. Fig. 5As can be seen, each wear measuring device 6, 6' has its own measuring area with electrically conductive material 9, 9' in a recess. The two wear measuring devices 6, 6' are positioned opposite each other at 180° to each other on the circumference of the stationary sliding ring 4. This ensures, in particular, that imbalances or undesirable waviness that could occur due to the placement of the wear measuring device 6 in the area of ​​the sliding surface 40 can be compensated for. It should also be noted that an alternative embodiment can be provided such that three wear measuring devices 6 are provided at equal intervals along the circumference, or four wear measuring devices 6 can be provided on the circumference with equal circumferential spacing. Otherwise, this embodiment corresponds to the first embodiment, so reference can be made to the description given there.

[0042] As illustrated in the exemplary embodiments, a mechanical seal assembly can thus be provided that enables predictive maintenance. Wear testing can be performed continuously during operation of the mechanical seal assembly or at preselected intervals. This allows for the timely replacement of the mechanical seal rings, thereby preventing a sudden, undesirable total failure of the mechanical seal assembly, which typically leads to a complete shutdown of the machine in which the mechanical seal assembly provides sealing. Reference symbol list

[0043] 1 Mechanical seal assembly 2 Mechanical seal 3 Rotating sliding ring 4 Stationary sliding ring 5 Sealing gap 6 Wear measuring device 6' Second wear measuring device 6a Measuring range 7 First electrically conductive filler material 8 Second electrically conductive filler material 9, 9' Electrically conductive material in recess 10 Automated measuring unit 11 Shaft 12 Product range 13 Atmospheric range 14 Housing 30 Sliding surface of the rotating sliding ring 31 Sliding ring carrier 40 Sliding surface of the stationary sliding ring 40a Rear side 41 Base body 42 Arc-shaped recess 43 First bore 44 Second bore 45 Bottom of the recess 60 Electrical voltage source 61 Supply line 61a Line section 62 Return line 62a Line section B Width D Diameter of the bores T Depth of the recess X-X Axial direction

Claims

1. Stationary slide ring of a mechanical seal assembly, comprising - a main body (41) having a slide surface (40) and - a wear-measuring device (6) arranged on the main body (41) to detect wear of the slide surface (40) of the stationary slide ring on the basis of a change in an electrical variable, - where the wear-measuring device (6) comprises an electrical voltage source (60), a measuring region (6a) on the slide surface (40), an electrical feed line (61), which electrically connects the voltage source (60) to the measuring region (6a), and an electrical return line (62), which electrically connects the measuring region (6a) to the voltage source (60), and - characterized in that the measuring region (6a) is arranged in a recess (42) in the slide surface (40).

2. Stationary slide ring according to claim 1, wherein the recess (42) is completely filled with an electrically conductive material (9).

3. Stationary slide ring according to one of the preceding claims, wherein a depth (T) of the recess (42) is selected such that, when the bottom (45) of the recess (42) is reached, the maximum permissible wear of the slide surface (40) of the stationary slide ring has been reached.

4. Stationary slide ring according to one of the preceding claims, wherein the recess (42) is a curved groove.

5. Stationary slide ring according to one of the preceding claims, wherein the electrical feed line (61) is guided through a first hole (43) in the main body (41) and / or wherein the electrical return line (62) is guided through a second hole (44) in the main body (41).

6. Stationary slide ring according to claim 5, wherein the first hole (43) and the second hole (44) are arranged on the slide surface (40) on the same radius.

7. Stationary slide ring according to claim 5 or 6, wherein the electrical feed line (61) is provided in the region of the first hole (43) by a first electrically conductive filler material (7), wherein the first filler material (7) completely fills the hole (43), and / or wherein the electrical return line (62) is provided in the region of the second hole (44) by a second electrically conductive filler material (8), wherein the second filler material (8) completely fills the second hole (44).

8. Stationary slide ring according to one of claims 5 to 7, wherein a width (B) of the recess (42) is greater than or equal to a diameter (D) of the first and second hole (43, 44).

9. Stationary slide ring according to one of claims 4 to 8, wherein the recess (42) lies on a circumferential portion of the slide surface (40) that is in the center in the radial direction of the stationary slide ring.

10. Stationary slide ring according to one of the preceding claims, comprising - a first wear-measuring device (6) and a second wear-measuring device (6'), which is opposite the first wear-measuring device (6) at 180°.

11. Mechanical seal assembly, comprising a mechanical seal (2) comprising a rotating slide ring (3) and a stationary slide ring (4) according to one of the preceding claims, wherein a sealing gap (5) is defined between a slide surface (30) of the rotating slide ring (3) and a slide surface (40) of the stationary slide ring (4), and comprising an automated measuring unit (10), which is configured to determine wear of the slide surface (40) of the stationary slide ring (4) on the basis of a change in electrical variables, in particular an electrical resistance, in a measuring region (6a) of a wear-measuring device (6) on the slide surface (40) of the stationary slide ring (4).

12. Mechanical seal assembly according to claim 11, wherein the automated measuring unit (10) is configured to carry out the wear determination continuously or in predetermined intervals.