Slide ring seal assembly

Abstract

The invention relates to a slide ring seal assembly for sealing a first region (11) from a second region (12), comprising: a slide ring seal (2) having a rotating slide ring (3) and a stationary slide ring (4), which define a sealing gap (5) between the sliding surfaces (30), (40) thereof, and a secondary sealing element (6) which seals a fluid path between the first region (11) and the second region (12), wherein the secondary sealing element (6) has a main body (60) having an axial subregion (65) extending in the axial direction (A), wherein the axial subregion (65) has an inner surface (65a) extending in the axial direction and an outer surface (65b) extending in the axial direction, wherein a first coating (61) is arranged on the inner surface (65a) and a second coating (62) is arranged on the outer surface (65b), and wherein the first coating (61) and the second coating (62) are configured to provide sealing in relation to components bearing against the coatings.

Description

[0001] Mechanical seal arrangement

[0002] Description

[0003] The present invention relates to a mechanical seal arrangement with an improved secondary sealing element.

[0004] Mechanical seal assemblies are known in various designs from the prior art. In practice, for various applications, O-rings or other elastomers are not used as secondary sealing elements, but rather complex secondary sealing elements. Such secondary sealing elements are often very complex and expensive to manufacture. During operation, particularly at high pressures, there is still a risk that secondary sealing elements will be drawn into a gap between an axially movable seal ring and a housing component, creating a hollow cylindrical sealing vane. In extreme cases, this can lead to failure of the secondary sealing element, which can lead to the failure of the mechanical seal assembly.

[0005] It is therefore an object of the present invention to provide a mechanical seal arrangement which enables a significant improvement of a secondary sealing element with a simple structure and simple, cost-effective manufacture.

[0006] This object is achieved by a mechanical seal arrangement having the features of claim 1. The subclaims show preferred developments of the invention.

[0007] The mechanical seal arrangement according to the invention for sealing a first region, in particular a pressure region, from a second region, in particular an atmospheric region, with the features of claim 1, on the other hand, has the advantage that an improved secondary sealing element can be provided which can withstand extremely high loads and has very good sealing performance. Furthermore, the secondary sealing element is also suitable for use at very high temperatures, in particular gaseous media with temperatures > 200°C, in particular > 800°C. This is achieved according to the invention in that the mechanical seal arrangement comprises a mechanical seal with a rotating seal ring and a stationary seal ring, which define a sealing gap between their sliding surfaces. The mechanical seal arrangement further comprises a secondary sealing element which seals a fluid path between the first and second regions.The secondary sealing element comprises a base body with an axial partial region extending in the axial direction. The axial partial region has an inner, annular surface and an outer, annular surface. A first coating is arranged on the inner annular surface and a second coating is arranged on the outer annular surface. The two coatings serve as sealing surfaces, which seal adjacent components against these two coatings. The first and second coatings are designed to seal components to which the coatings are in contact. The base body and the coatings are made of different materials. The base body can be optimized with regard to rigidity and the coatings can be optimized with regard to sealing effect. The coatings therefore have better sealing effects than the base body.

[0008] Preferably, the hardness of the base body is greater than the hardness of the coating. The base body thus exhibits very high resistance to extrusion into a gap. The coatings are preferably made of the same material and can be adapted to the medium to be sealed for optimized sealing properties.

[0009] The base body is preferably made of PEEK or PA or metal, in particular copper or aluminum or iron alloys or the like.

[0010] The first and second coatings are preferably made of the same material. The coating material is preferably a silicone material, PTFE, or preceramics, especially polyphosphazene.

[0011] Further preferably, the secondary sealing element is arranged to be axially movable and, in particular, preloaded in the axial direction by means of a preloading device. The first and second coatings enable sufficient mobility of the secondary sealing element in the axial direction without excessive wear occurring on the secondary sealing element.

[0012] Further preferably, the axial portion of the base body has a first and a second leg portion. The two leg portions are arranged at the free end of the axial portion and define a gap between them. In section, the axial portion thus has a U-shaped cross-section. Further preferably, the first and second coatings are arranged exclusively on the first and second leg portions. This allows the coating costs to be kept relatively low, since only the two leg portions need to be coated.

[0013] Further preferably, the main body of the secondary sealing element is designed such that the axial partial region has a base region with a first inner diameter D1 and a second outer diameter D2. The second leg region has a third outer diameter D3, which is greater than the second outer diameter D2. The first leg region has a fourth inner diameter D4, which is smaller than the first inner diameter D1. As a result, the first and second leg regions protrude slightly radially inwards and outwards from a base region of the axial partial region, so that in particular axial mobility of the secondary sealing element is improved. A coating can also be applied to the first and second leg regions in a simpler manner.

[0014] More preferably, the first and second coatings are of equal thickness. Preferably, the thickness of the first and second coatings is in a range from 5 μm to 100 μm, in particular in a range from 10 μm to 30 μm, and particularly preferably 20 μm.

[0015] The secondary sealing element further preferably has a corner region on an inner circumference on a side facing the sliding ring, where no coating is arranged. The corner region is formed by a radial surface of the radial sub-region and an axial surface of the axial sub-region and, in particular, abuts a gap where there is a risk of extrusion of the secondary sealing element into the gap during operation. The corner region is thus part of the base body of the secondary sealing element, and the material for the base body is selected such that extrusion into a gap does not occur during operation.

[0016] According to a further preferred embodiment of the invention, the secondary sealing element is arranged directly on a rear side of the sliding ring.

[0017] The sliding ring on which the secondary sealing element is arranged is preferably axially prestressed by means of a prestressing device.

[0018] Further preferably, the secondary sealing element comprises a base body with a radial portion extending in the radial direction and an axial portion extending in the axial direction. The secondary sealing element therefore preferably has an L-shaped cross-section. Alternatively, the secondary sealing element has a mirrored L-shape in cross-section.

[0019] Further preferably, the secondary sealing element has a third coating on a side facing the sliding ring. The third coating is preferably only partially formed on the side of the secondary sealing element facing the sliding ring. The third coating is particularly preferably formed on an end region of the base body that is located outward in the radial direction, preferably on the radial partial region.

[0020] Further preferably, the secondary sealing element is arranged on a thrust ring. The thrust ring is preferably preloaded in the axial direction by means of a preloading device. Thus, the secondary sealing element is axially preloaded via the thrust ring by means of the preloading device.

[0021] The sliding ring on which the secondary sealing element is arranged is preferably the stationary sliding ring.

[0022] Further preferably, the mechanical seal arrangement does not have a support ring between the secondary sealing element and the mechanical seal.

[0023] To reduce the tendency of the secondary sealing element to shrink at the inner circumference, the secondary sealing element is preferably radially slotted. This means that short slots extending in the radial direction are provided on the inner circumference of the secondary sealing element. The slots are preferably also coated.

[0024] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0025] Fig. 1 is a schematic sectional view of a mechanical seal arrangement according to a first embodiment of the invention,

[0026] Fig. 2 is a schematic sectional view of a secondary sealing element of the

[0027] Mechanical seal arrangement of Fig. 1 ,

[0028] Fig. 3 is a schematic sectional view of a secondary sealing element according to a second embodiment of the invention,

[0029] Fig. 4 is a schematic sectional view of a secondary sealing element according to a third embodiment of the invention,

[0030] Fig. 5 is a schematic sectional view of a secondary sealing element according to a fourth embodiment of the invention,

[0031] Fig. 6 is a schematic sectional view of a mechanical seal arrangement according to a fifth embodiment of the invention,

[0032] Fig. 7 is a schematic sectional view of the secondary sealing element of Fig. 6,

[0033] Fig. 8 is a schematic sectional view of a secondary sealing element according to a sixth embodiment of the invention, Fig. 9 is a schematic sectional view of a secondary sealing element according to a seventh embodiment of the invention, and

[0034] Fig. 10 is a schematic sectional view of a secondary sealing element according to an eighth embodiment of the invention.

[0035] A mechanical seal arrangement 1 according to a preferred embodiment of the invention is described in detail below with reference to Figures 1 and 2.

[0036] The mechanical seal arrangement 1 is designed to seal a first region 11, which is under high pressure, from a second region 12, which is, for example, the atmospheric region.

[0037] The mechanical seal 2 comprises a rotating seal ring 3, which is fixedly connected to a rotating component 9, and a stationary seal ring 4. The stationary seal ring 4 is arranged on a housing 10.

[0038] The rotating seal ring 3 has a first sliding surface 30, and the stationary seal ring 4 has a second sliding surface 40. A sealing gap 5 is defined between the first sliding surface 30 and the second sliding surface 40.

[0039] A secondary sealing element 6 is arranged on the rear side 41 of the stationary sliding ring 4, which can be seen in detail in Fig. 2.

[0040] The secondary sealing element 6 is preloaded against the stationary sliding ring 4 via a pressure ring 8 and a preloading device 7, which has a plurality of spring elements acting in the axial direction A and exerting a preload force.

[0041] The secondary sealing element 6 is arranged on an axial ring area 10a of the housing.

[0042] The mechanical seal arrangement shown in Fig. 1 can thus follow the axial movements of the rotating component 9, whereby, in particular, the secondary sealing element 6 must also follow the axial movements. To ensure good axial mobility of the stationary seal ring 4, a gap 13 is provided between the stationary seal ring 4 and an annular region 10a of the housing 10.

[0043] During operation, there is always a risk in the state of the art that material of the secondary sealing element is extruded into such a gap 13 between the stationary sliding ring 4 and the ring area 10a.

[0044] According to the invention, as shown in Fig. 2, however, a secondary sealing element 6 is provided, which has a base body 60 with a radial partial region 64 and an axial partial region 65. In section, the base body 60 thus has an L-shape. As can also be seen from Fig. 2, the axial partial region 65 of the base body 60 has an inner surface 65a extending in the axial direction A and an outer surface 65b extending in the axial direction.

[0045] The two surfaces 65a, 65b can be arranged parallel to each other or at an acute angle, preferably an equal acute angle, to a central axis XX of the mechanical seal arrangement.

[0046] A first coating 61 is arranged on the inner surface 65a, and a second coating 62 is arranged on the outer surface 65b of the axial portion 65 (see Fig. 2). The two coatings 61, 62 have the same extent in the axial direction A and each extend completely along the circumference of the inner surface 65a and the outer surface 65b.

[0047] The axial portion 65 further has a gap 68, so that a first leg portion 66 and a second leg portion 67 are formed on the axial portion 65. In section, the free end of the axial portion 65 thus has a substantially C-shape.

[0048] The base body 60 is now made of a harder material than the material of the first and second coatings. For example, the base body is made of PEEK, and the first and second coatings are made of PTFE.

[0049] Thus, a corner region 69 of the base body 60, which, as shown in Fig. 1, bears against the gap 13 present between the stationary slide ring 4 and the ring region 10a. The inner surface 65a is not coated in a region arranged at the corner region (cf. Fig. 2). Since the base body 60 is made of a very hard material, e.g. PEEK, there is no risk of material of the base body being extruded into the gap 13 during operation. With secondary sealing elements which are made entirely of PTFE, for example, there is always a risk of material of the secondary sealing element being extruded into the gap 13 due to the lower hardness than PEEK.

[0050] The first coating 61 is designed to seal the ring region 10a of the housing 10. The second coating 62 is designed to seal the pressure ring 8.

[0051] As can be seen from Fig. 2, the first coating 61 is not completely formed on the inner surface 65a. This simplifies the mobility of the secondary sealing element 6 in the axial direction A, which can occur during operation when the mechanical seal arrangement 1 must accommodate axial movements of the rotating component 9. The first coating 61 ensures that a seal is maintained between the first region 11 and the second region 12 via the secondary sealing element 6 in every operating situation. The harder base body 60 prevents extrusion into the gap 13, and the softer coatings 61, 62 ensure the seal on the secondary sealing element 6.

[0052] Figures 3 to 5 show further embodiments of a mechanical seal arrangement with different secondary sealing elements, wherein identical or functionally identical parts are designated by the same reference numerals.

[0053] The second embodiment in Fig. 3 essentially corresponds to the first embodiment, with the first and second coatings 61, 62 being only partially applied to the inner and outer surfaces 65a, 65b of the axial portion 65 of the base body. As shown in Fig. 3, an extension of the first and second coatings 61, 62 corresponds to a maximum depth T of the gap 68 in the axial direction A.

[0054] Fig. 4 shows a third exemplary embodiment, which essentially corresponds to the second exemplary embodiment. In the third exemplary embodiment, the first leg region 66 and the second leg region 67 are designed differently than in the first exemplary embodiment. As can be seen from Fig. 4, the axial partial region 65 has a base region 65c with a first inner diameter D1 and a second outer diameter D2. The second leg region 67 has a third outer diameter D3, which is greater than the second diameter D2. The first leg region 66 has a fourth inner diameter D4, which is smaller than the first diameter D1 (cf. Fig. 4). Thus, the first and second leg regions 66, 67 are widened radially inwards and outwards, respectively.

[0055] The first coating 61 and the second coating 62 are then formed exclusively on the first leg region 66 and the second leg region 67. Thus, the first and second coatings 61, 62 can be formed with a very small thickness, while still ensuring that no contact occurs between the base region 65c and the annular region 10a or the thrust ring 8 during operation. A gap is thus always present radially inside and radially outside the base region 65c of the axial sub-region 65, which ensures the distance between the secondary sealing element and the adjacent components. This achieves particularly good axial mobility of the secondary sealing element 6.

[0056] Fig. 5 shows a secondary seal 6 according to a fourth exemplary embodiment of the invention. The secondary seal 6 of the fourth exemplary embodiment has a third coating 63. The third coating 63 is arranged on the radial partial region 64 and directed towards the stationary slide ring 4. This also achieves a seal in the radial direction R on the secondary sealing element 6. The third coating 63 is in contact with the rear side 41 of the stationary slide ring 4 and seals thereon. Furthermore, the axial partial region 65 running in the axial direction A does not have two leg regions like the previous exemplary embodiments, but is formed continuously. The first coating 61 and the second coating 62 are only partially provided on the axial partial region 65.

[0057] Figures 6 and 7 show a mechanical seal assembly 1 according to a fifth embodiment of the invention. As can be seen from Figure 6, the mechanical seal assembly 1 has a mechanical seal carrier 43 for holding the stationary seal ring 4. An O-ring 42 is arranged on a rear side 41 of the stationary seal ring 4. The mechanical seal carrier 43 is connected to the housing 10 via a pin 44 to prevent torque transfer.

[0058] The secondary sealing element 6, which can be seen in detail in Fig. 7, is arranged between the slide ring carrier 43 and the housing 10. Thus, the first coating 61 is in contact with the slide ring carrier 43, and the second coating 62 is in contact with the housing 10.

[0059] As can be seen in detail in Fig. 7, the secondary sealing element 6 of the fifth exemplary embodiment has only an axial partial region 65. The secondary sealing element 6 has no radial partial region. The first and second coatings 61, 62 are not arranged completely on the inner and outer surfaces of the axial partial region 65, which in the fifth exemplary embodiment forms the sole base body 60 of the secondary sealing element 6. The secondary sealing element 6 has a first leg region 66 and a second leg region 67 with a gap 68 between them, so that a shape with a C-shaped cross-section is formed.

[0060] Fig. 8 shows a secondary sealing element 6 of a mechanical seal arrangement according to a sixth embodiment of the invention. The sixth embodiment essentially corresponds to the fifth embodiment, wherein, as can be seen from Fig. 8, the first coating 61 and the second coating 62 have an axial extent that corresponds to a maximum depth T of the gap 68 in the axial direction A.

[0061] Fig. 9 shows a secondary sealing element 6 of a mechanical seal assembly according to a seventh embodiment of the invention. The seventh embodiment essentially corresponds to the sixth embodiment and the third embodiment shown in Fig. 4, without the radial portion of the third embodiment. Thus, in Fig. 9, the axial portion 65 also forms the base body 60.

[0062] Fig. 10 shows a secondary sealing element 6 of a mechanical seal arrangement according to an eighth embodiment of the invention. The eighth embodiment corresponds to the sixth embodiment, with the eighth embodiment not having an intermediate space 68. Regarding the embodiments shown in Figs. 6 to 10, it should be noted that a third coating 63, as shown in the fourth embodiment of Fig. 5, can also be provided on a side facing toward the stationary seal ring 4.

[0063] In addition to the above written description of the invention, reference is hereby explicitly made to the graphic representation of the invention in the figures for its supplementary disclosure.

[0064] List of reference symbols

[0065] 1 mechanical seal arrangement

[0066] 2 mechanical seals

[0067] 3 rotating slide ring

[0068] 4 stationary sliding ring

[0069] 5 Sealing gap

[0070] 6 Secondary sealing element

[0071] 7 Pre-tensioning device

[0072] 8 Pressure ring

[0073] 9 rotating component

[0074] 10 housings

[0075] 10a ring area

[0076] 11 first area (print area)

[0077] 12 second area (atmospheric area)

[0078] 13 gap

[0079] 30 first sliding surface

[0080] 40 second sliding surface

[0081] 41 Back of the stationary sliding ring

[0082] 42 O-ring

[0083] 43 Slide ring carrier

[0084] 44 Pin to prevent torque transfer

[0085] 60 basic bodies

[0086] 61 first coating

[0087] 62 second coating

[0088] 63 third coating

[0089] 64 radial sub-area

[0090] 65 axial section

[0091] 65a axially extending inner surface

[0092] 65b axially extending outer surface

[0093] 65c base range

[0094] 66 first thigh area

[0095] 67 second thigh area

[0096] 68 space

[0097] 69 Corner area

[0098] A axial direction

[0099] D1 first diameter

[0100] D2 second diameter

[0101] D3 third diameter

[0102] D4 fourth diameter

[0103] R radial direction

[0104] T Depth

[0105] XX Central axis

Claims

Claims 1. A mechanical seal arrangement for sealing a first region (11) from a second region (12), comprising: a mechanical seal (2) with a rotating seal ring (3) and a stationary seal ring (4), which define a sealing gap (5) between their sliding surfaces (30), (40), a secondary sealing element (6) which seals a fluid path between the first region (11) and the second region (12), wherein the secondary sealing element (6) has a base body (60) with an axial partial region (65) extending in the axial direction A, wherein the axial partial region (65) has an inner surface (65a) extending in the axial direction and an outer surface (65b) extending in the axial direction, wherein a first coating (61) is arranged on the inner surface (65a) and a second coating (62) is arranged on the outer surface (65b), and wherein the first coating (61) and the second coating (62) are arranged,to seal components adjacent to the coatings.

2. Mechanical seal arrangement according to claim 1, wherein a hardness of the base body (60) is greater than a hardness of the first and second coatings (61), (62).

3. Mechanical seal arrangement according to claim 1 and 2, wherein the base body (60) is made of PEEK or PA or metal and / or wherein the first and second coating are made of PTFE or silicone or preceramics.

4. Mechanical seal arrangement according to one of the preceding claims, wherein the secondary sealing element (6) is arranged to be axially movable and is prestressed in the axial direction A by means of a prestressing device (7).

5. Mechanical seal arrangement according to one of the preceding claims, wherein the axial partial region (65) has a first leg region (66) and a second leg region (67) which are arranged at a free end of the axial partial region (65) and wherein an intermediate space (68) is present between the first leg region (66) and the second leg region (67).

6. A mechanical seal assembly according to claim 5, wherein the first coating (61) is arranged only on the first leg region (66) and the second coating (62) is arranged only on the second leg region (67).

7. Mechanical seal arrangement according to claim 5 or 6, wherein the axial portion (65) has a base portion (65c) without coating with a first inner diameter D1 and with a second outer diameter D2 and the second leg portion (67) has a third outer diameter D3 which is larger than the second outer diameter D2, and the first leg portion (66) has a fourth inner diameter D4 which is smaller than the first inner diameter D1.

8. Mechanical seal arrangement according to one of the preceding claims, wherein the first coating (61) is of the same thickness as the second coating (62).

9. Mechanical seal arrangement according to one of the preceding claims, wherein the first coating (61) and / or the second coating (62) have a thickness in a range from 5 pm to 100 pm, in particular in a range from 10 pm to 30 pm and further in particular 20 pm.

10. Mechanical seal arrangement according to one of the preceding claims, wherein the secondary sealing element (6) has, on an inner peripheral region, a corner region (69) on a side of the secondary sealing element directed towards the sliding ring, on which corner region no coating is arranged.

11. Mechanical seal arrangement according to one of the preceding claims, wherein the secondary sealing element (6) is arranged directly on the rear side (41) of the sliding ring.

12. Mechanical seal arrangement according to one of the preceding claims, wherein the secondary sealing element (6) has a base body (60) with a radial partial region (64) extending in the radial direction (R) and an axial partial region (65) extending in the axial direction (A).

13. Mechanical seal arrangement according to claim 12, wherein a third coating (63) is arranged on a side directed towards the sliding ring.

14. Mechanical seal arrangement according to one of claims 12 or 13, wherein the secondary sealing element (6) is arranged on a pressure ring (8).

15. Mechanical seal arrangement according to one of claims 11 to 14, wherein the sliding ring on which the secondary sealing element (6) is arranged is the stationary sliding ring (4).

16. Mechanical seal arrangement according to one of the preceding claims, wherein no support ring is arranged between the secondary sealing element (6) and the sliding ring.

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