EP3478993A1

EP3478993A1 - Slide ring seal arrangement with coated bellows unit

Info

Publication number: EP3478993A1
Application number: EP17721543.1A
Authority: EP
Inventors: Andreas PEHL; Jörg Thomas THELKE; Tino MÖLLER; Joachim Skrzidlo
Original assignee: EagleBurgmann Germany GmbH and Co KG
Current assignee: EagleBurgmann Germany GmbH and Co KG
Priority date: 2016-06-30
Filing date: 2017-04-18
Publication date: 2019-05-08
Also published as: CN109416127A; DE102016211816A1; US20190195367A1; CA3026147C; WO2018001592A1; CA3026147A1; DE102016211816B4

Abstract

The invention relates to a slide ring seal arrangement comprising a rotating slide ring (2) and a stationary slide ring (3) which define a sealing gap (4) between one another; a bellows unit (5) having a bellows element (50), a bellows carrier (51) and a slide ring carrier (52); wherein the bellows element (50) is connected to the bellows carrier (51) and the slide ring carrier (52) in a fluid-tight manner; wherein the bellows unit (5) has a side facing a product (7) and an atmosphere side (8); wherein that side of the bellows unit (5) that is directed towards the product (7) has a non-stick coating (6); wherein the bellows element (50) is a metal bellows; and wherein the slide ring inserted in the slide ring carrier (52) of the bellows unit (5) is inserted loosely.

Description

Mechanical seal assembly with coated bellows unit

description

The present invention relates to a mechanical seal assembly with a coated bellows unit for ensuring a function of the bellows unit.

Mechanical seal assemblies are known in the prior art in various configurations. In order to ensure a repositioning of a sliding ring in the axial direction during operation of the mechanical seal assembly, bellows members are used, which are in communication with the nachzuschetzenden in the axial direction of the sliding ring. The bellows elements ensure axial mobility of this sliding ring.

However, mechanical seals also need to have sealing functions on media such as e.g. Hot water or liquid concrete, in which deposits occur on the bellows element meet. Such deposits fill over time the bellows folds of the bellows element, so that the axial mobility of the bellows element is no longer present. This concerns in particular bellows, which are made of metal, since they have relatively stiff bellows folds.

From DE 102014207188 B4 a mechanical seal assembly with an elastic bellows element made of an elastomeric material is known, which has a non-stick coating. This bellows element has no bellows folds, but a curved flexible intermediate bellows area, in which the above-mentioned deposition problem does not occur.

Furthermore, with the use of bellows units in mechanical seal assemblies with metal bellows, the problem arises that the metal bellows usually has to be welded to a sliding ring carrier. The slip ring is fastened, for example by means of a shrink connection in Gleitringträger. The production of the shrink connection is carried out before the welding of the bellows element to the slip ring carrier, since a slip ring carrier with welded bellows element would not fit into a shrinking machine. Therefore occur in mechanical seal assemblies with bellows units through the Shrinking process often a delay of the sliding ring in the slip ring carrier, which can involve elaborate reworking.

It is therefore an object of the present invention to provide a mechanical seal assembly with a bellows unit, which has a long life even in the sealing of deposits tend to media with a simple structure and simple, cost manufacturability and provides a long life and reliability.

This object is achieved by a mechanical seal assembly having the features of claim 1. The dependent claims show preferred developments of the invention. The mechanical seal assembly according to the invention with the features of claim 1 has the advantage that deposits on a bellows element of a bellows unit can be prevented. Thereby, a life and reliability of the bellows unit and in particular a mobility of a bellows member can be maintained for a long time. The bellows unit comprises a bellows element, a bellows carrier and a sliding ring carrier. The bellows element is fluid-tightly connected to the bellows carrier and the sliding ring carrier. The bellows element has a non-stick coating on a product side which is in contact with the medium to be sealed. Preferably, the complete product side of the bellows unit, i.e., the bellows member, the bellows carrier and the slip ring carrier, has the coating. The bellows element is a metal bellows, in particular with a large number of bellows folds. Furthermore, a sliding ring is loosely inserted into the slip ring carrier of the bellows unit. As a result, stresses or distortions or the like. Can be avoided in the sliding ring.

Thus, according to the invention, the complete bellows unit is provided with a non-stick coating on one product side, i.e., the flexible bellows member, the bellows carrier and the slip ring carrier. For the preparation of the metal bellows is already attached to the bellows support and the slip ring carrier, e.g. welded. During this welding process, the sliding ring need not be arranged in the sliding ring carrier, since the sliding ring is later loosely inserted into the slip ring carrier.

Preferably, the non-stick coating is a DLC coating. DLC coatings have very good non-stick properties and can be easily and inexpensively applied to the product side of the bellows unit with a relatively small thickness.

The non-stick coating preferably has a thickness in a range of 1/200 to 1/10, in particular 1/100 of a bellows thickness. This ensures that a dimension of the bellows unit changes only minimally in the radial direction through the coating. The Thickness of the coating on the bellows unit is preferably in a range of 0.1 μηη to 20 μηη and is in particular in a range of 0.7 μηη to 3 μηη.

More preferably, the mechanical seal assembly further comprises a first sleeve having a first annular flange at a first end, and preferably a second annular flange at a second end. The first sleeve is provided to connect the loosely fitted slip ring with the slip ring carrier. Here, the slide ring carrier has a groove for receiving the first annular flange, wherein between the groove and the first annular flange a snap connection is provided. The snap connection is thus provided by an undercut, so that a quick and easy Klickmontage the first sleeve on Gleitringträger is possible. More preferably, the first sleeve comprises a second annular flange and the loosely mounted sliding ring has a shoulder on a side facing the other sliding ring side. As a result, a mobility of the loosely fitted sliding ring between the second annular flange and the Gleitringträger is limited in the axial direction of the mechanical seal assembly. Preferably, the bellows member has a plurality of bellows creases, each bellows fold having a maximum depth which is equal to or less than a double maximum width of the bellows fold. This definition of the depth to the width of the bellows fold ensures that all areas of the bellows fold can be coated.

Preferably, a secondary seal, in particular an O-ring, is arranged between the loosely inserted slide ring and the slide ring carrier. The secondary seal is used in particular to fix the loosely inserted slide ring in Gleitringträger. The fixation by means of the secondary seal thereby ensures that no undesirable stresses or the like. Are introduced into the loosely inserted seal ring. The secondary seal is preferably provided in an annular recess on the sliding ring carrier. In order to allow sufficient mobility of the coated bellows member in the axial direction, a ratio of a hardness of the coated bellows member to an modulus of elasticity of the coated bellows member is in a range of 1: 6 to 1: 8. The ratio of hardness to modulus of coated Balgelements is particularly preferably 1: 7.

More preferably, the non-stick coating is provided on the bellows unit throughout. Thus, the non-stick coating is entirely provided on a product side, i.e., all areas of the bellows unit which are in contact with the medium to be sealed.

More preferably, a first welded connection is formed between the metal bellows and the bellows carrier, and a second welded connection is formed between the metal bellows and the sliding ring carrier. The two welds are preferred before Coating of the bellows unit made to prevent damage to the coating by subsequent welding operations.

More preferably, the bellows unit has a first non-stick coating on the product-facing side and a second non-stick coating on the atmosphere side. Thus, the bellows unit and in particular the bellows element is coated from both sides. Thus, if leakage of the medium to be sealed occurs across the seal gap between the slip rings to the atmosphere side of the bellows unit, deposits on the atmosphere side of the bellows unit may also be prevented from forming deposits or the like. Thus, a particularly long life and good mobility of the bellows unit can be ensured. A thickness of the second coating is particularly preferably equal to a thickness of the first coating. Furthermore, the coatings are preferably the same. More preferably, the bellows unit, i. the bellows element, the bellows carrier and the sliding ring carrier, completely coated from both sides.

The mechanical seal assembly according to the invention is particularly preferably used for sealing media in which deposits often occur. Such media are, for example, liquid concrete or hot water, with limescale often arise in hot water.

Hereinafter, a preferred embodiment of the invention will be described in detail with reference to the accompanying drawings. In the drawings: Fig. 1 is a schematic sectional view of a mechanical seal assembly according to a first embodiment of the invention;

FIG. 2 is a schematic sectional view of a bellows unit of FIG. 1; FIG.

3 is a schematic sectional view of a loop of a bellows element of FIG. 2; and FIG. 4 is a schematic sectional view of a loop of a bellows element of FIG

Belge unit according to a second embodiment of the invention.

Hereinafter, a mechanical seal assembly 1 according to a first preferred embodiment of the invention will be described in detail.

As can be seen from Fig. 1, the mechanical seal assembly 1 comprises a mechanical seal with a rotating seal ring 2 and a stationary seal ring 3, which define a sealing gap 4 between them. _c

5

Furthermore, the mechanical seal assembly 1 comprises a bellows unit 5, which can be seen in detail from FIG. The bellows unit 5 comprises an elastic bellows element 50, a bellows carrier 51 and a sliding ring carrier 52. The elastic bellows element 50 is a bellows made of a metal material, in particular spring steel. In this embodiment, the bellows element is provided as a round bellows. It should be noted that a bellows with sharp folds can be provided as a flexible bellows element.

As can be seen from FIG. 2, a side of the bellows unit 5 facing a product 7 has a non-stick coating 6. The non-stick coating 6 is a DLC coating in this embodiment. The non-stick coating 6 is completely provided on the side of the bellows unit 5 directed towards the product 7. The coating 6 has no interruption or the like. On.

In the bellows support 51, as shown in Fig. 2, further provided a threaded bore 54, which has no coating. The threaded bore 54 is covered during the coating process, for example with a plug. By means of the threaded bore 54, the bellows unit 5 can be fixed to a second sleeve 12 (see FIG. The second sleeve 12 serves to fix the bellows carrier 51 on the shaft 15.

As can be seen from FIG. 3, the non-stick coating 6 has a constant first thickness D1, which has approximately 1/100 of a constant second thickness D2 of the bellows element 50. In Fig. 3, the size ratios of the thicknesses D1 and D2 are not shown to scale for ease of illustration. The non-stick coating 6 is completely formed in a bellows fold of the bellows element 50. A width B of the bellows fold is defined by a distance between two radially outermost points 16, 17 delimiting the bellows fold. A depth T of the bellows crease is defined by a distance of a radially innermost point 18 of the bellows crease to the line connecting the two radially outermost points. A depth T corresponds to a double width B of the bellows fold.

The thickness D1 of the non-stick coating 6 is in a range of 0.1 μηη to 20 μηη and is in particular between 0.7 μηη and 3 μηη.

Further, a secondary seal 9 is provided in the form of an O-ring between the rotating seal ring 2 and the Gleitringträger 52. The secondary seal 9 is arranged in a first groove 53 in the sliding ring carrier 52. The secondary seal 9 prevents product 7 from the product side to an atmosphere side 70 along the side facing away from the stationary seal ring 3 region of the rotating seal ring 2 passes. The stationary seal ring 3 is fixed to a housing 30. The secondary seal 9 thus clamps the rotating seal ring 2 between the slide ring carrier 52 and the first sleeve 1 1 a.

The Gleitringträger 52 takes, as shown in Fig. 1 it can be seen, the rotating seal ring 2 loose. The rotating seal ring 2 is fixed at its inner circumference by a first sleeve 1 1. The first sleeve 1 1 comprises a cylindrical main body 20, a first annular flange 21 at a first end and a second annular flange 22 at a second end.

Between the first annular flange 21 and a second groove 55 in the slip ring carrier 52, a snap connection 10 is formed. The snap connection 10 is joined by simple axial sliding of the Gleitringträgers 52 on the first sleeve 1 1. The second annular flange 22 prevents in the loosely assembled state of the rotating seal ring 2 that the rotating seal ring 2 is moved in the axial direction X-X in the direction of the stationary seal ring 3.

Furthermore, the flexible bellows element 50 is connected to the bellows carrier 51 by means of a first weld seam 13 with the sliding ring carrier 52 and a second weld seam 14. To produce the coated bellows unit 5, the bellows element 50 is thus first welded to the bellows carrier 51 and the sliding ring carrier 52. The coating then takes place with the non-stick coating 6 of the bellows unit 5, the side of the bellows unit 5 facing the product 7 being completely coated. In this case, any existing openings with plugs or covers or the like. Covered to prevent a coating on inner areas, which are later directed to the atmosphere side 70 in the assembled state, is present. Subsequently, the rotating seal ring 2 is loosely inserted into the Gleitringträger 52 and the first sleeve 1 1 pushed in the axial direction until the snap connection 10 is formed between the first annular flange 21 and the second groove 55 in the Gleitringträger 52. Subsequently, a mounting on a shaft 15th

The one-sided coating of the bellows unit 5 on the side directed towards the product 7 thus prevents deposits from forming on the side of the bellows unit 5 facing the product 7. The non-stick coating 6 prevents the adhesion of such particles. As a result, the movability of the flexible bellows element 50 in the axial direction X-X of the mechanical seal assembly 1 is not restricted. Also no deposits occur in the region of the Gleitringträgers 52 and the bellows support 51 on the side facing the product 7 on.

Since the bellows unit 50 has already been assembled before the coating, the sliding ring to be introduced into the sliding ring carrier 52 can become loose in the subsequent assembly step be inserted. This has the great advantage that it can be prevented that the sliding ring is exposed to high thermal loads, for example when the bellows element 50 is fixed to the sliding ring carrier 52, and that damage to the sliding ring can thereby occur. Thus, by the idea of a metallic bellows member 50 coated with non-stick coating 6, a loosely inserted rotary seal ring 2 can be used, on which no damage during assembly and no rework or the like is necessary. A positioning of the rotating sliding ring 2 on the sliding ring carrier 52 by means of a releasable snap connection 10. This snap connection 10 is easy to prepare and provides a secure holding the rotating seal ring second

4 shows a bellows loop of a bellows unit 5 according to a second exemplary embodiment of the invention. In contrast to the first embodiment, the elastic bellows element 50 is coated on both sides. The bellows unit 5 of the second embodiment thus comprises a first non-stick coating 6, on the side of the elastic bellows element 50 facing the product 7 and a second non-stick coating 60 on the side of the elastic bellows element 50 facing the atmosphere side 70. The second non-stick coating 60 has a third thickness D3. The third thickness D3 is equal to the first thickness D1. Preferably, the first and second release coatings are each DLC coatings. The two-sided coating of the elastic bellows element 50 ensures that, if the medium to be sealed leaks through the sealing gap between the sliding rings to the atmosphere side 70, deposition on the elastic bellows element 50 on the atmosphere side 70 is prevented. Thus, a particularly long life and mobility of the bellows unit 5 can be ensured. Preferably, the complete bellows unit, ie the elastic bellows element 50, the bellows support 51 and the sliding ring carrier 52 is completely provided with the non-stick coating.

_QQ

LIST OF REFERENCE NUMBERS

1 mechanical seal assembly

2 rotating seal ring

3 stationary sliding ring

4 sealing gap

5 bellows unit

6 first non-stick coating / first DLC coating

7 product

9 O-ring / secondary seal

10 releasable snap connection

1 1 first sleeve

12 second sleeve

13 first weld

14 second weld

15 wave

16, 17 radially outermost points of the bellows element

18 radially innermost point of a bellows fold

20 cylindrical main body

21 first annular flange

22 second annular flange

30 housing

50 elastic bellows element

51 bellows carrier

52 sliding ring carrier

53 first groove

54 threaded hole

55 second groove

60 second non-stick coating / second DLC coating

70 atmosphere side

D1 first thickness

D2 second thickness

D3 third thickness

B width

T depth

X-X axial direction

Claims

claims

1 . A mechanical seal assembly (1) comprising:

a rotating seal ring (2) and a stationary seal ring (3) defining therebetween a seal gap (4);

- A bellows unit (5) with a bellows element (50), a bellows support (51) and a

Sliding ring carrier (52);

the bellows member (50) fluidly connected to the bellows carrier (51) and the slip ring carrier (52);

wherein the bellows unit (5) has a side facing an product (7) and an atmosphere side (70);

wherein the product (7) facing side of the bellows member (50) has a non-stick coating (6);

the bellows element (50) being a metal bellows; and

wherein in the Gleitringträger (52) of the bellows unit (5) inserted sliding ring is loosely inserted.

2. Arrangement according to claim 1, wherein the non-stick coating (6) is a DLC coating.

3. Arrangement according to one of the preceding claims, wherein the non-stick coating (6) has a first thickness (D1), which in a range of 1/200 to 1/10, in particular 1/100 of a second thickness (D2) of the bellows element (50) is.

4. Arrangement according to claim 3, wherein the first thickness (D1) of the non-stick coating (6) is between 0.1 μηη to 20 μηη.

5. Arrangement according to one of the preceding claims, further comprising a first sleeve (1 1) with a first radially outwardly directed annular flange (21) at a first end of the first sleeve, wherein the first sleeve (1 1) the loosely inserted sliding ring on Sliding ring carrier (52) holds and on the sliding ring carrier (52) has a groove (55) for receiving the first annular flange (21) is provided, wherein a snap connection (10) between the groove (55) and the first annular flange (21) is provided.

6. Arrangement according to claim 5, wherein the first sleeve (1 1) has a second annular flange (22) at a second end of the first sleeve, wherein the loosely inserted sliding ring (2) between the second annular flange (22) and the Gleitringträger (52 ) is held.

An assembly according to any one of the preceding claims, wherein the bellows member (50) comprises a plurality of bellows creases, each bellows fold having a maximum depth (T) equal to or less than a double maximum width (B) of the bellows fold.

Arrangement according to one of the preceding claims, wherein a secondary seal (9), in particular an O-ring, is arranged between the loosely inserted slide ring (2) and the slide ring carrier (52).

Arrangement according to claim 8, wherein the sliding ring carrier (52) has a groove (53) in which the secondary seal (9) is arranged.

Arrangement according to one of the preceding claims, wherein the coated bellows element (50) has a ratio of hardness to modulus of elasticity of the coated bellows element in a range of 1: 6 to 1: 8.

1 1. Arrangement according to one of the preceding claims, wherein the non-stick coating (6) is formed continuously on the side facing the product (7) of the bellows unit (5).

12. Arrangement according to one of the preceding claims, wherein between the bellows member (50) and the Gleitringträger (52) a first welded joint (13) and between the bellows member (50) and the bellows support (51) a second welded joint (14) is provided.

13. Arrangement according to one of the preceding claims, wherein the bellows element (5) on a side facing the atmosphere (70) side, a second non-stick coating (60).