mechanical seal arrangement

Abstract

Mechanical seal arrangement for sealing a first area (11) from a second area (12), comprising: - a mechanical seal (2) with a rotating sliding ring (3) and a stationary sliding 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 area (11) and the second area (12), - wherein the secondary sealing element (6) has a base body (60) with an axial sub-section (65) extending in the axial direction A, - wherein the axial sub-region (65) has an axially extending inner surface (65a) and an axially extending outer surface (65b), - 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 designed to seal against components adjacent to the coatings, and - where the hardness of the base body (60) is greater than the hardness of the first and second coatings (61), (62).

Description

[0001] The present invention relates to a mechanical seal arrangement with an improved secondary sealing element.

[0002] Mechanical seal assemblies are known in various configurations from the prior art. In practice, in different 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. In operation, especially at high pressures, there is also the risk that secondary sealing elements will be drawn into a gap between an axially movable sliding ring and a housing component, creating a hollow cylindrical sealing flange. In extreme cases, the secondary sealing element may fail, which can lead to the failure of the mechanical seal assembly. DE 20 2009 008 088 U1 discloses a mechanical seal with a secondary sealing element that seals against a rear side of the stationary sliding ring.Furthermore, DE 25 57 988 A1 discloses a mechanical seal in which a secondary seal in the form of a coated O-ring is known.

[0003] It is therefore an object of the present invention to provide a mechanical seal arrangement which, with a simple design and simple, cost-effective manufacturability, enables a significant improvement of a secondary sealing element.

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

[0005] The mechanical seal arrangement according to the invention for sealing a first area, in particular a pressure area, from a second area, in particular an atmospheric area, with the features of claim 1, has the advantage that an improved secondary sealing element can be provided which withstands the highest loads and exhibits very good sealing performance. Furthermore, the secondary sealing element is also suitable for use at very high temperatures, in particular with gaseous media at temperatures > 200°C, in particular > 800°C.

[0006] According to the invention, this is achieved by the mechanical seal assembly comprising a mechanical seal with a rotating sliding ring and a stationary sliding ring, which define a sealing gap between their sliding surfaces. The mechanical seal assembly 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 axially extending subregion. The axial subregion 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 against adjacent components at these two coatings.The first and second coatings are designed to seal against the components to which they are applied. The base body and the coatings are made of different materials. The base body can be optimized for stiffness, and the coatings can be optimized for sealing performance. The coatings therefore exhibit better sealing properties than the base body.

[0007] Furthermore, the base material has a greater hardness than the coating. The base material therefore 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 with regard to optimized sealing properties.

[0008] The base body is preferably made of PEEK or PA or metal, in particular copper or aluminium or iron alloys or the like.

[0009] The first and second coatings are preferably made of the same material. The coating material is preferably a silicone material, PTFE, or preceramics, in particular polyphosphazene.

[0010] Preferably, the secondary sealing element is arranged to be axially movable and is, in particular, prestressed in the axial direction by means of a prestressing device. Here, the first and second coatings enable sufficient movement of the secondary sealing element in the axial direction without excessive wear occurring on the secondary sealing element.

[0011] Preferably, the axial section of the base body has a first and second leg section. The two leg sections are arranged at the free end of the axial section and define a gap between them. In section, the axial section thus has a U-shaped cross-section.

[0012] It is also preferred that the first and second coatings are applied exclusively to the first and second leg areas. This allows the coating costs to be kept relatively low, as only these two leg areas need to be coated.

[0013] Preferably, the base body of the secondary sealing element is designed such that the axial section has a base area with a first inner diameter D1 and a second outer diameter D2. The second leg area has a third outer diameter D3, which is larger than the second outer diameter D2. The first leg area has a fourth inner diameter D4, which is smaller than the first inner diameter D1. This causes the first and second leg areas to project slightly radially inwards and outwards from the base area of ​​the axial section, thus improving the axial movement of the secondary sealing element. Furthermore, a coating can be applied to the first and second leg areas more easily.

[0014] Preferably, the first and second coatings are of the same thickness. Preferably, the thickness of the first and second coatings is in the range of 5 µm to 100 µm, particularly in the range of 10 µm to 30 µm, and is most preferably 20 µm.

[0015] The secondary sealing element preferably has a corner region on an inner circumference on a side facing the sliding ring, where no coating is applied. 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, during operation, there is a risk of extrusion of the secondary sealing element into the gap. The corner region is thus part of the main body of the secondary sealing element, and the material for the main body is selected such that no extrusion into a gap occurs 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 pre-tensioned by means of a pre-tensioning device.

[0018] Preferably, the secondary sealing element comprises a base body with a radially extending section and an axially extending section. Preferably, the secondary sealing element thus has an L-shaped cross-section. Alternatively, the secondary sealing element has a mirrored L-shape in cross-section.

[0019] 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 a radially outwardly extending end region of the base body, preferably on the radial portion.

[0020] Preferably, the secondary sealing element is arranged on a pressure ring. The pressure ring is preferably pre-tensioned axially by means of a pre-tensioning device. Thus, the secondary sealing element is axially pre-tensioned via the pressure ring by means of the pre-tensioning device.

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

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

[0023] To reduce the tendency of the secondary sealing element to shrink at its inner circumference, the secondary sealing element is preferably radially slotted. That is, short, radially extending slots are provided on the inner circumference of the secondary sealing element. Preferably, the slots are also coated.

[0024] 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 according to a first embodiment of the invention, Fig. 2 a schematic sectional view of a secondary sealing element of the mechanical seal assembly of Fig. 1, Fig. 3 a schematic sectional view of a secondary sealing element according to a second embodiment of the invention, Fig. 4 a schematic sectional view of a secondary sealing element according to a third embodiment of the invention, Fig. 5 a schematic sectional view of a secondary sealing element according to a fourth embodiment of the invention, Fig. 6 a schematic sectional view of a mechanical seal arrangement according to a fifth embodiment of the invention, Fig. 7 a schematic sectional view of the secondary sealing element of Fig. 6, Fig. 8 a schematic sectional view of a secondary sealing element according to a sixth embodiment of the invention, Fig. 9 a schematic sectional view of a secondary sealing element according to a seventh embodiment of the invention, and Fig. 10 a schematic sectional view of a secondary sealing element according to an eighth embodiment of the invention.

[0025] The following refers to the Fig. 1 and Fig. 2 a mechanical seal arrangement 1 according to a preferred embodiment of the invention is described in detail.

[0026] The mechanical seal arrangement 1 is designed to seal a first area 11, which is under high pressure, against a second area 12, which is, for example, the atmospheric area.

[0027] The mechanical seal 2 comprises a rotating sliding ring 3, which is rigidly connected to a rotating component 9, and a stationary sliding ring 4. The stationary sliding ring 4 is arranged on a housing 10.

[0028] The rotating sliding ring 3 has a first sliding surface 30 and the stationary sliding 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.

[0029] A secondary sealing element 6 is arranged on the rear side 41 of the stationary sliding ring 4, which in detail consists of Fig. 2 is evident.

[0030] 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 axial direction A that exert a preload force.

[0031] The secondary sealing element 6 is arranged on an axial ring area 10a of the housing.

[0032] The in Fig. The mechanical seal arrangement shown in Figure 1 can thus follow axial movements of the rotating component 9, whereby the secondary sealing element 6 must also follow the axial movements. For good axial mobility of the stationary sliding ring 4, a gap 13 is provided between the stationary sliding ring 4 and a ring area 10a of the housing 10.

[0033] In the prior art, there is always a risk that material of the secondary sealing element will be extruded into such a gap 13 between the stationary sliding ring 4 and the ring area 10a.

[0034] According to the invention, as in Fig. As shown in Figure 2, a secondary sealing element 6 is now provided, which has a base body 60 with a radial section 64 and an axial section 65. In section, the base body 60 thus has an L-shape.

[0035] What's next? Fig. As can be seen in Figure 2, the axial sub-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.

[0036] The two surfaces 65a, 65b can be arranged parallel to each other or at an acute angle, preferably the same acute angle, to a central axis XX of the mechanical seal arrangement.

[0037] 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 sub-area 65 (see figure). 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.

[0038] The axial section 65 further comprises a gap 68, such that a first leg section 66 and a second leg section 67 are formed on the axial section 65. In section, the free end of the axial section 65 thus essentially has a C-shape.

[0039] 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 of PTFE.

[0040] Thus, a corner region 69 of the basic body 60 is located, which, as in Fig. Figure 1 shows the gap 13, which is located between the stationary sliding ring 4 and the ring area 10a. The inner surface 65a is uncoated in an area located at the corner. (cf. Fig. 2) Since the main body 60 is made of a very hard material, e.g., PEEK, there is no risk during operation of material from the main body being extruded into the gap 13. With secondary sealing elements, which are made entirely of PTFE, for example, there is always a risk, due to their lower hardness than PEEK, that material from the secondary sealing element will be extruded into the gap 13.

[0041] The first coating 61 is configured to seal the ring area 10a of the housing 10. The second coating 62 is configured to seal the pressure ring 8.

[0042] As from Fig. As can be seen in Figure 2, the first coating 61 is not fully formed on the inner surface 65a. This facilitates movement of the secondary sealing element 6 in the axial direction A, which can occur during operation when the mechanical seal assembly 1 has to follow axial movements of the rotating component 9. The first coating 61 ensures that a seal between the first area 11 and the second area 12 is maintained via the secondary sealing element 6 in every operating situation.

[0043] The harder base body 60 prevents extrusion into the gap 13 and the softer coatings 61, 62 ensure sealing at the secondary sealing element 6.

[0044] The Fig. 3, Fig. 4 to Fig. Figure 5 shows further embodiments of a mechanical seal arrangement with different secondary sealing elements, wherein identical or functionally identical parts are designated with the same reference numerals.

[0045] The second embodiment in Fig. 3 essentially corresponds to the first embodiment, wherein the first and second coatings 61, 62 are only partially applied to the inner and outer surfaces 65a, 65b of the axial sub-region 65 of the base body. As in Fig. As shown in Figure 3, the extent of the first and second coatings 61, 62 corresponds to a maximum depth T of the space 68 in the axial direction A.

[0046] Fig. Figure 4 shows a third embodiment, which essentially corresponds to the second embodiment. In the third embodiment, the first leg section 66 and the second leg section 67 are designed differently compared to the first embodiment. As shown in Figure 4, the first leg section 66 and the second leg section 67 are designed differently compared to the first embodiment. Fig. As can be seen in Figure 4, the axial section 65 has a base section 65c with a first inner diameter D1 and a second outer diameter D2. The second leg section 67 has a third outer diameter D3, which is larger than the second diameter D2. The first leg section 66 has a fourth inner diameter D4, which is smaller than the first diameter D1 (see Figure 4). Fig. 4). Thus, the first and second leg regions 66, 67 are widened radially inwards and outwards, respectively.

[0047] 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, respectively. 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 ring region 10a or the pressure ring 8 during operation. A gap is therefore always present radially inside and radially outside the base region 65c of the axial section 65, which ensures the distance of the secondary sealing element from the adjacent components. This results in particularly good axial movement of the secondary sealing element 6.

[0048] Fig. Figure 5 shows a secondary seal 6 according to a fourth embodiment of the invention. The secondary seal 6 of the fourth embodiment has a third coating 63. The third coating 63 is arranged on the radial section 64 and is directed towards the stationary sliding ring 4. This achieves a seal on the secondary sealing element 6 in the radial direction R as well. The third coating 63 is in contact with the rear surface 41 of the stationary sliding ring 4 and seals against it. Furthermore, the axial section 65 extending in the axial direction A does not have two leg sections as in the previous embodiments, but is continuous. The first coating 61 and the second coating 62 are only partially provided on the axial section 65.

[0049] The Fig. 6 and Fig. Figure 7 shows a mechanical seal arrangement 1 according to a fifth embodiment of the invention. As shown in Figure 7, the following applies: Fig. As can be seen in Figure 6, the mechanical seal assembly 1 has a sliding ring carrier 43 for holding the stationary sliding ring 4. An O-ring 42 is arranged on a rear side 41 of the stationary sliding ring 4. The sliding ring carrier 43 is connected to the housing 10 via a pin 44 to prevent torque transmission.

[0050] The secondary sealing element 6, which in detail consists of Fig. As can be seen in Figure 7, it is arranged between the sliding ring carrier 43 and the housing 10. Thus, the first coating 61 is in contact with the sliding ring carrier 43 and the second coating 62 is in contact with the housing 10.

[0051] How in detail from Fig. As can be seen in Figure 7, the secondary sealing element 6 of the fifth embodiment has only an axial section 65. The secondary sealing element 6 has no radial section. The first and second coatings 61, 62 are not completely arranged on the inner and outer surfaces of the axial section 65, which in the fifth embodiment forms the sole base body 60 of the secondary sealing element 6. The secondary sealing element 6 has a first leg section 66 and a second leg section 67 with a gap 68 between them, resulting in a C-shaped cross-section.

[0052] Fig. Figure 8 shows a secondary sealing element 6 of a mechanical seal arrangement according to a sixth embodiment of the invention. The sixth embodiment corresponds essentially to the fifth embodiment, wherein, as shown in Figure 8, the following applies: Fig. As can be seen in Figure 8, the first coating 61 and the second coating 62 have an axial extension corresponding to a maximum depth T of the space 68 in the axial direction A.

[0053] Fig. Figure 9 shows a secondary sealing element 6 of a mechanical seal arrangement according to a seventh embodiment of the invention. The seventh embodiment corresponds essentially to the sixth embodiment and the one described in Figure 9. Fig. 4. The third embodiment shown, without the radial section of the third embodiment. Thus, in Fig. 9 the axial sub-area 65 also the base body 60.

[0054] Fig. Figure 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, except that the eighth embodiment does not have an intermediate space 68.

[0055] Among those in the Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. In the embodiments shown in 10, it should be noted that a third coating 63, as in the fourth embodiment, is also provided on a side facing towards the stationary sliding ring 4. Fig. 5 shown, may be provided.

[0056] In addition to the above written description of the invention, explicit reference is hereby made to the graphic representation of the invention in the figures for its supplementary disclosure. Reference symbol list 1 Mechanical seal assembly 2 mechanical seals 3 rotating sliding ring 4 stationary sliding ring 5 Sealing gap 6 Secondary sealing element 7 Pre-tensioning device 8 pressure ring 9 rotating component 10 cases 10a Ring area 11 first area (printing area) 12 second area (atmospheric area) 13 gaps 30 first sliding surface 40 second sliding surface 41 Back side of the stationary sliding ring 42 O-ring 43 Sliding ring carriers 44 Pin to prevent torque transmission 60 basic shapes 61 first coating 62 second coating 63 third coating 64 radial sub-area 65 axial sub-area 65a axially extending inner surface 65b axially extending outer surface 65c basic range 66 first thigh area 67 second thigh area 68 space 69 Corner area A axial direction D1 first diameter D2 second diameter D3 third diameter D4 fourth diameter R radial direction T depth XX central axis

Claims

[1] Mechanical seal arrangement for sealing a first area (11) from a second area (12), comprising: - a mechanical seal (2) with a rotating sliding ring (3) and a stationary sliding 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 area (11) and the second area (12), - wherein the secondary sealing element (6) has a base body (60) with an axial sub-section (65) extending in the axial direction A, - wherein the axial sub-region (65) has an axially extending inner surface (65a) and an axially extending outer surface (65b), - 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 designed to seal against components adjacent to the coatings, and - where the hardness of the base body (60) is greater than the hardness of the first and second coatings (61), (62). [2] Mechanical seal arrangement according to claim 1, wherein the base body (60) is made of PEEK or PA or metal and / or wherein the first and second coatings are made of PTFE or silicone or preceramics. [3] Sliding ring seal arrangement according to one of the preceding claims, wherein the secondary sealing element (6) is arranged to be axially movable and is pre-tensioned in axial direction A by means of a pre-tensioning device (7). [4] Sliding ring seal arrangement according to one of the preceding claims, wherein the axial part section (65) has a first leg section (66) and a second leg section (67) which are arranged at a free end of the axial part section (65) and wherein a space (68) is provided between the first leg section (66) and the second leg section (67). [5] Mechanical seal arrangement according to claim 4, 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). [6] Mechanical seal arrangement according to claim 4 or 5, wherein the axial part section (65) has a base section (65c) without coating having a first inner diameter D1 and a second outer diameter D2, and the second leg section (67) has a third outer diameter D3 which is larger than the second outer diameter D2, and the first leg section (66) has a fourth inner diameter D4 which is smaller than the first inner diameter D1. [7] Mechanical seal arrangement according to one of the preceding claims, wherein the first coating (61) is the same thickness as the second coating (62). [8] 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 of 5 µm to 100 µm, in particular in a range of 10 µm to 30 µm and further in particular 20 µm. [9] Mechanical seal arrangement according to one of the preceding claims, wherein the secondary sealing element (6) has a corner region (69) on an inner circumferential region on a side of the secondary sealing element facing the mechanical seal, on which no coating is arranged. [10] 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 mechanical seal. [11] Sliding ring seal arrangement according to one of the preceding claims, wherein the secondary sealing element (6) has a base body (60) with a radial part (64) extending in the radial direction (R) and an axial part (65) extending in the axial direction (A). [12] Mechanical seal arrangement according to claim 11, wherein a third coating (63) is arranged on a side facing the mechanical seal. [13] Sliding ring seal arrangement according to one of claims 11 or 12, wherein the secondary sealing element (6) is arranged on a pressure ring (8). [14] Mechanical seal arrangement according to one of claims 10 to 13, wherein the sliding ring on which the secondary sealing element (6) is arranged is the stationary sliding ring (4). [15] Mechanical seal arrangement according to one of the preceding claims, wherein no support ring is arranged between the secondary sealing element (6) and the mechanical seal.

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