Slide-ring seal assembly
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- EAGLEBURGMANN GERMANY GMBH &CO KG
- Filing Date
- 2024-07-09
- Publication Date
- 2026-05-20
AI Technical Summary
Mechanical seal arrangements experience leakage due to disruptive forces, particularly at high pressures and temperatures, causing inversion moments that alter the sealing gap geometry and lead to unstable leakage behavior.
A mechanical seal arrangement with rotating and stationary seal rings, where a torque-neutral point on the sliding rings' backside contact surface prevents inversion moments by ensuring the contact force does not exert a torque, maintaining the sealing gap geometry and reducing leakage.
This design achieves significantly improved leakage stability and reduced leakage quantities, maintaining constant leakage even with thermal and mechanical changes, allowing for effective countermeasures against excessive leakage at reduced costs.
Smart Images
Figure EP2024069295_16012025_PF_FP_ABST
Abstract
Description
[0001] Mechanical seal arrangement
[0002] Description
[0003] The present invention relates to a mechanical seal arrangement with significantly improved leakage stability.
[0004] Mechanical seal assemblies are known in various designs from the state of the art. Due to the inherent design principle, mechanical seal assemblies can exhibit a certain degree of leakage during operation due to the sealing gap between the sliding surfaces of the seal rings. To prevent or minimize this leakage, considerable technical effort is sometimes undertaken. During operation, various disturbing forces can act on a mechanical seal. These disturbing forces are particularly pronounced at high pressures, e.g., over 100 x 10 5Pa and high temperatures, e.g. greater than 100°C, is further increased. The slide rings of the mechanical seal are often inserted into metallic slide ring carriers. The back of the slide rings rests on a contact surface in the axial direction on the slide ring carriers. A contact force is transmitted to this contact surface. In the event of radial component expansion of the slide ring and / or the slide ring carrier, which can have thermal and / or mechanical causes, radial friction forces occur on the contact surface between the back of the slide ring and the slide ring carrier. Depending on the direction of the friction forces, i.e. radially outwards or radially inwards, the friction forces can reverse their direction of action. This results in a so-called inversion moment, which is used to load the slide ring. The inversion moment on the slide ring then leads to a change in the geometry at the sealing gap, which changes the leakage behavior of the mechanical seal.
[0005] It is therefore an object of the present invention to provide a mechanical seal arrangement which, while being simple in design and easy and cost-effective to manufacture, prevents a slipping moment from being exerted on a sliding ring.
[0006] This object is achieved by a mechanical seal assembly having the features of claim 1. The subclaims disclose preferred developments of the invention. The mechanical seal assembly according to the invention having the features of claim 1 has the advantage that no or a significantly reduced change in the geometry of a sealing gap of a mechanical seal occurs during operation. This significantly improves the stability of a leak during operation. Countermeasures against excessive leakage during operation can thus be implemented very effectively and at reduced costs.
[0007] This is achieved according to the invention in that the mechanical seal arrangement comprises a mechanical seal with a rotating and a stationary seal ring. A sealing gap is defined between the sliding surfaces of the rotating and stationary seal rings, through which leakage can occur. Furthermore, a component is provided which is arranged on a rear side of at least one of the seal rings. The seal ring can be the rotating or the stationary seal ring. This one seal ring has a radial contact surface on a rear side which is in direct contact with a surface of the component facing this rear side of the seal ring and forms a radial contact area. In this case, a moment-neutral point of a cross-section of one seal ring and the radial contact area on the rear side of the seal ring are selected such that they lie in a common plane. The plane is perpendicular to a central axis of the mechanical seal.The moment-neutral point of the cross-section is a point where forces acting at this point exert no torque on the seal ring. In a three-dimensional, annular seal ring, the moment-neutral points form a moment-neutral line. In a cross-section, the moment-neutral point can also be the centroid of the cross-section.
[0008] This ensures that a contact force acting in the axial direction from the component onto one of the seal rings cannot exert a slipping moment on the seal ring. The point of application of the contact force lies in the plane in which the moment-neutral point of the seal ring's cross-section also lies. This means that the contact force cannot exert a moment on the seal ring, so that undesirable slipping of the seal ring around the moment-neutral point due to the missing moment of the contact force does not occur during operation. This means that the geometry of the sealing gap, as designed during the calculation of the mechanical seal, can be retained during operation, so that any potential leakage can be kept essentially constant even under changing temperatures and / or mechanical loads. This enables effective selection of possible countermeasures against excessive leakage during operation.
[0009] The component arranged on the rear side of one of the sliding rings is preferably a sliding ring carrier. The sliding ring carrier is particularly preferably made of a metallic material. Alternatively, the component arranged on the rear side of the sliding ring is a thrust ring, which is preloaded in particular in the axial direction. The thrust ring is also preferably made of a metallic material.
[0010] According to a further preferred embodiment of the invention, the sliding ring preventing the slipping moment has a stepped rear side with a first and a second radial rear side surface. The first rear side surface is the radial contact surface of the sliding ring. Although this increases the manufacturing effort for the sliding ring due to the stepped rear side, the stepped rear side can ensure in a relatively simple manner that the moment-neutral point of the cross-section of the sliding ring and the radial contact area, which lies between the radial contact surface of the sliding ring and the surface of the component, lie in the same plane.
[0011] Further preferably, a secondary sealing element is provided on the second radial rear surface of the rear side of the sliding ring for sealing between the rear side of the sliding ring and the component arranged on the rear side of the sliding ring, in particular the sliding ring carrier. The secondary sealing element is preferably an elastomer sealing element, e.g., an O-ring.
[0012] Particularly preferably, the secondary sealing element is arranged close to an inner circumference or an outer circumference of the second rear side surface of the stepped rear side. Alternatively, the secondary sealing element is preferably arranged exactly on a radially inner edge on the rear side of the sliding ring.
[0013] The seal ring can be either the rotating or the stationary seal ring or both seal rings, where a moment-neutral point and a radial contact area on a rear side of the seal ring lie in a common plane.
[0014] Further preferably, the component located on the rear side of the sliding ring is made of a metallic material, in particular steel, and / or the sliding ring is preferably made of a ceramic material, in particular SiC or WC. This material combination has proven itself in principle, and the inventive concept can reliably prevent an undesirable slipping moment during operation.
[0015] The mechanical seal arrangement is preferably intended for sealing a product which is subject to high pressure, in particular greater than 100 x 10 5 Pa, and high temperatures, especially greater than 100°C.
[0016] Embodiments of the invention will be described in detail below 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,
[0017] Fig. 2 is a schematic, enlarged partial sectional view of the mechanical seal arrangement of Figure 1,
[0018] Fig. 3 is a diagram showing the leakage behavior of the mechanical seal arrangement of the first embodiment as a function of pressure and speed over time,
[0019] Fig. 4 is a diagram showing a leakage behavior of a mechanical seal arrangement according to the prior art and
[0020] Fig. 5 is a schematic sectional view of a mechanical seal arrangement according to a second embodiment.
[0021] Two embodiments of the invention are described in detail below with reference to Figures 1 to 5.
[0022] Figures 1 to 3 show a first embodiment of the invention.
[0023] As can be seen from Figure 1, the mechanical seal arrangement 1 comprises a mechanical seal 2 with a rotating seal ring 3 and a stationary seal ring 4. A sealing gap 5 is defined between the opposing sliding surfaces of the rotating and stationary seal rings.
[0024] The mechanical seal arrangement 1 seals a product area 16 from an atmospheric area 17 or another area on a shaft 18.
[0025] The rotating slide ring 3 is connected to the rotating shaft 18 by means of a slide ring carrier 8 in such a way that torque is transmitted from the shaft via the slide ring carrier 8 to the rotating slide ring 3.
[0026] The stationary seal ring 4 is arranged on a housing 19. A preloading device comprising a preload element 15 and a pressure ring 9 on a rear side 40 of the stationary seal ring 4 preloads the stationary seal ring 4 in the axial direction XX against the rotating seal ring 3.
[0027] A secondary sealing element 10, for example an O-ring, is arranged on the pressure ring 9.
[0028] As can be seen in particular from Figure 2, the rotating slide ring 3 has a stepped rear side 30. The rear side is divided by a step into a first radial rear side surface 31 and a second radial rear side surface 32. An edge 33 is formed on a radial inner region of the second radial rear side surface 32. The secondary sealing element 10 is arranged on the edge 33 on the rear side 30 of the rotating slide ring 3 in a groove in the slide ring carrier 8. By positioning this secondary sealing element 10 on the edge 33, a gap 13 is created between the second rear side surface 32 and the slide ring carrier 8, in which gap the same pressure essentially prevails as in the product area 16. By positioning the secondary sealing element 10 on the edge 33 of the rotating slide ring 3, a contact force F acts primarily on the first rear side surface 31 of the rear side 30 of the rotating slide ring 3.
[0029] Figures 1 and 2 schematically illustrate the resulting contact force F, which occurs between a surface 14 of the slide ring carrier 8 and the first rear surface 31. This results in a radial contact area 6 between the rotating slide ring 3 and the slide ring carrier 8, which is present between the first radial rear surface 31 and the surface 14 of the slide ring carrier 8. Frictional forces F1 and F2 occur at this radial contact area 6 during operation due to thermal and / or mechanical influences. As can be seen from Figure 2, the frictional forces F1 and F2 are present in opposite radial directions starting from the point of application of the contact force F.
[0030] As can be further seen from Figures 1 and 2, a moment-neutral point 7 of a cross-section of the profile of the rotating seal ring 3 lies in a first plane 11, in which the radial contact area 6 is also arranged. Thus, any frictional forces F1 and F2 that may occur can act on the rotating seal ring in such a way that no slipping moment is exerted on the rotating seal ring 3.
[0031] As a result, the geometry of the sealing gap 5 of the mechanical seal 2 can remain stable during operation even when mechanical and / or thermal operating changes and corresponding expansions of the components of the mechanical seal 2, in particular the rotating seal ring 3 and / or the seal ring carrier 8, occur, and the contact force F does not exert a moment around the moment-neutral point 7. Thus, the sealing gap 5 remains constant and stable during operation, thereby achieving improved leakage stability of the mechanical seal arrangement during operation.
[0032] Figures 3 and 4 show diagrams illustrating the positive influence of the invention on the leakage stability of the mechanical seal arrangement during operation. Figure 3 shows the mechanical seal arrangement 1 according to the invention, and Figure 4 shows a mechanical seal arrangement according to the prior art. In both diagrams, a leakage curve A, a pressure curve B, and a speed curve C are plotted against time t. Leakage curve A shows the leakage V across the sealing gap 5 against time t. Pressure curve B shows the pressure changes in the pressure p in the sealing gap 5 starting from a machine standstill (at time t = 0), and speed curve C shows a speed n of the rotating seal ring 3 or shaft 18 against time t.
[0033] As can be seen from Figures 3 and 4, when the machine starts up, the speed n begins to rise steeply to a speed of approximately 11,200 rpm. After a short start-up phase, the speed n remains essentially constant.
[0034] As shown in the pressure curve B in both Figure 3 and the prior art in Figure 4, the pressure p builds up in a slight step-like manner from standstill to a constant pressure p.
[0035] Leakage V is shown in Figures 3 and 4 by leakage curve A. As is immediately apparent, the invention (Figure 3) results in a significantly reduced change in leakage quantities after start-up compared to the seal according to the prior art (Figure 4). This clearly demonstrates that the invention achieves significantly improved leakage stability during operation without any jumps. Furthermore, leakage during operation is also stabilized, and in particular, the absolute leakage quantity is significantly reduced by the inventive design compared to the prior art.
[0036] Thus, according to the invention, the leakage behavior of the mechanical seal assembly during operation can be improved both in terms of leakage stability and the absolute amount of leakage. Due to the much more constant leakage across the sealing gap 5 during operation, the invention, with appropriate countermeasures, can significantly improve the overall leakage compared to the prior art.
[0037] Figure 5 shows a second embodiment of a mechanical seal arrangement 1, wherein identical or functionally identical parts are designated by the same reference numerals as in the first embodiment.
[0038] The second embodiment essentially corresponds to the first embodiment, although, in contrast to the first embodiment, in the second embodiment, the invention is provided on both the rotating seal ring 3 and the stationary seal ring 4. As can be seen from Figure 5, the stationary seal ring 4 is also designed in a stepped manner. A first radial rear surface 41 and a second radial rear surface 42 are provided on a rear side 40 of the stationary seal ring 4. A first secondary sealing element 10 is arranged on an edge 43 on the rear side 40.
[0039] The first secondary sealing element 10 is arranged in a thrust ring 9 in a groove formed therein. Radially outside the first secondary sealing element 10 on the rear side of the stationary seal ring 4, between the stationary seal ring 4 and the thrust ring 9, there is a gap 13 in which the pressure from the product area 16 essentially prevails. The thrust ring 9 has an inverted T-shape in cross-section. The stationary seal ring 4 is arranged on a sleeve-like section of the thrust ring 9 and is axially movable. For sealing, a second secondary sealing element 10a is provided between the thrust ring 9 and the housing 19 of the mechanical seal arrangement. Thus, the radial contact area 6 between the stationary seal ring 4 and the sleeve-like area of the thrust ring 9 lies in a second plane 12, in which a moment-neutral point 7 of the stationary seal ring 4 also lies.Thus, contact forces F, which can generate frictional forces F1 and F2 acting in the radial direction at the radial contact area 6 during operation due to mechanical and / or thermal changes, have no torque-generating influence on the stationary seal ring 4. This also prevents the stationary seal ring 4 from becoming warped during operation. The rotating seal ring 3 is designed as in the first embodiment, so reference can be made to the description given there.
[0040] Thus, in the second embodiment, both seal rings 3, 4 incorporate measures to prevent the occurrence of a slipping moment. This leads to even further improved leak stability during operation and correspondingly reduced leakage rates during operation. Otherwise, this embodiment corresponds to the first embodiment, so reference can be made to the description given there.
[0041] List of reference symbols
[0042] 1 mechanical seal arrangement
[0043] 2 mechanical seals
[0044] 3 rotating slide ring
[0045] 4 stationary sliding ring
[0046] 5 Sealing gap
[0047] 6 radial contact area
[0048] 7 moment-neutral point of the cross-section of a sliding ring
[0049] 8 sliding ring carriers
[0050] 9 Pressure ring
[0051] 10 first secondary sealing element (O-ring)
[0052] 10a second secondary sealing element (O-ring)
[0053] 11 first level
[0054] 12 second level
[0055] 13 gap
[0056] 14 Surface of a component facing a rear side of a sliding ring
[0057] 15 Preload element
[0058] 16 Product area
[0059] 17 Atmospheric area
[0060] 18 Wave
[0061] 19 housings
[0062] 30 Back of the rotating slide ring
[0063] 31 first radial rear surface
[0064] 32 second radial rear surface
[0065] 33 edge
[0066] 40 Back of the stationary sliding ring
[0067] 41 first radial rear surface
[0068] 42 second radial rear surface
[0069] 43 edge
[0070] A leakage curve
[0071] B Pressure curve
[0072] C Speed curve
[0073] F contact force in axial direction
[0074] F1 Friction force in radial direction
[0075] F2 Friction force in radial direction opposite to friction force F1 n Speed p Pressure t Time
[0076] V Leakage
[0077] XX Axial direction
Claims
Claims 1. Mechanical seal arrangement, 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, and . a component having a surface (14), the component being arranged on a rear side (30, 40) of one of the sliding rings (3, 4), . wherein one sliding ring (3, 4) has a radial contact surface (31, 41) on the rear side (30, 40), which is in direct contact with the surface (14) of the component facing the sliding ring and forms a radial contact area (6), and . wherein a moment-neutral point (7) of a cross-section of one of the sliding rings (3, 4) and the radial contact region (6) lie in a common plane (11, 12), the plane (11, 12) being perpendicular to an axial direction XX of the mechanical seal (2).
2. Mechanical seal arrangement according to claim 1, wherein the component with the surface (14) directed towards the sliding ring is a sliding ring carrier (8).
3. Mechanical seal arrangement according to claim 1, wherein the component with the surface (14) directed towards the sliding ring is a pressure ring (9).
4. Mechanical seal arrangement according to one of the preceding claims, wherein the one sliding ring has a step-shaped rear side (30, 40) with a first radial rear side surface (31, 41) and a second radial rear side surface (32, 42), wherein the first radial rear side surface (31, 41) bears against the surface (14) of the component and the radial contact region (6) is formed between the first radial rear side surface (31, 41) and the surface (14) of the component.
5. Mechanical seal arrangement according to claim 4, wherein a secondary sealing element (10) is arranged on the second radial rear side surface (32, 42).
6. Mechanical seal arrangement according to claim 5, wherein the secondary sealing element (10) is arranged close to an inner circumference or outer circumference of the second radial rear side surface (32, 42), or wherein the secondary sealing element (10) is arranged on the second radial rear side surface (32, 42) exactly at an edge (33, 43) on the rear side (30, 40) of the seal ring.
7. Mechanical seal arrangement according to one of the preceding claims, wherein the one sliding ring is the rotating sliding ring (3) or wherein the one sliding ring is the stationary sliding ring (4).
8. Mechanical seal arrangement according to one of the preceding claims, wherein the rotating and stationary seal rings (3, 4) each have a step-shaped rear side (30, 40) and wherein the moment-neutral point (7) of the cross section of the rotating and stationary seal rings and the respective radial contact region (6) on the rear side (30, 40) of the rotating and stationary seal rings lie in a common plane (11, 12), wherein the plane (11, 12) is perpendicular to the axial direction XX of the mechanical seal (2).
9. Mechanical seal arrangement according to one of the preceding claims, wherein the component with the surface (14) is made of a metallic material.
10. Mechanical seal arrangement according to one of the preceding claims, wherein the rotating and / or stationary seal ring (3, 4) is made of a ceramic material.