Mechanical Seal Device
The mechanical seal device with a bellows and spring system addresses the mobility issues of metal bellows under high pressure and temperature, enabling reliable sealing in extreme conditions and expanding its application to gas turbines and compressors.
Patent Information
- Application Number
- JP2025527659
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-11-17
- Filing Date
- 2023-10-24
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2043-10-24
AI Technical Summary
Existing mechanical seal devices face limitations in using metal bellows as secondary seals due to stiffness and lack of axial mobility, especially under high pressures and temperatures, which restrict their application range.
A mechanical seal device incorporating a bellows as a secondary sealing element with a spring device providing preload, where the bellows and spring exert preload forces in opposite directions, allowing for optimized axial mobility and flexibility, particularly suitable for high-pressure and high-temperature environments.
The solution enables the use of bellows in mechanical seals for media at pressures exceeding 100 Pa and temperatures above 550°C, expanding the application range to gas turbines and gas pipeline compressors, while ensuring reliable sealing and minimal wear.
Smart Images
Figure 2025536631000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention is particularly 5 The present invention relates to a mechanical seal device having an improved preloading device for preloading a mechanical seal under high pressure exceeding 100 Pa and, in particular, for sealing media at high temperatures exceeding 550°C. [Background technology]
[0002] Various embodiments of mechanical seal devices are known from the prior art. In these cases, a secondary sealing element is used at the rear face of the slide ring to prevent leakage past the rear face of the slide ring. Examples of such secondary sealing elements include O-rings and bellows. However, the use of bellows is limited for its intended purpose by external parameters of the mechanical seal device, such as pressure, material strength, chemical resistance, and temperature. In this case, the bellows is used as a dynamic secondary seal, specifically to allow axial displacement of the mechanical seal. Metal bellows can actually be used to seal against high pressures and high temperatures. However, metal bellows are very stiff and cannot achieve the required axial mobility, especially of the secondary seal, without significant force fluctuations. Summary of the Invention [Problem to be solved by the invention]
[0003] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a mechanical seal arrangement that has a simple design, is easy and cost-effective to manufacture, yet provides an improved secondary sealing element. [Means for solving the problem]
[0004] This object is achieved by a mechanical sealing device having the features of claim 1. The dependent claims disclose preferred developments of the invention.
[0005] In this case, the mechanical seal device according to claim 1 has the advantage that a bellows can be used as a secondary sealing element, which offers great flexibility in terms of its characteristics, particularly in terms of material selection and sealing properties. In this case, a spring device additionally provides preload to one of the slide rings. For this purpose, the mechanical seal device of the present invention includes a rotating slide ring and a fixed slide ring, which define a sealing gap between their sealing surfaces. Furthermore, a combined preload-sealing device is provided for axially sealing and preloading one of the slide rings. The preload-sealing device includes a circumferentially closed bellows and a spring device as a spring system. The bellows is configured as a secondary sealing element and has a sealing function, for example, on the rear surface of one of the slide rings. Furthermore, the bellows exerts a first preload force F1 in a first axial direction X1, and the spring device exerts a second preload force F2 in a second axial direction X2. In this case, the first and second axial directions are opposite to each other, and the preload forces of the bellows and the spring device are directed in different directions. In this case, the absolute values of the first preload and second preload are different so that the resultant force F0 of the preload-seal system always acts in the direction of the seal gap of the mechanical seal, creating preload. In this way, the axial preload of the two slide rings of the mechanical seal is achieved by preloads of different magnitudes and directions.
[0006] Therefore, the bellows can be optimized in particular with respect to axial mobility, since an additional spring device is available for the preload force and the design is not significantly affected by the preload force constraints when designing the bellows. Thus, greater freedom is available for the design of the bellows, especially for 200 x 10 5 This makes it possible to seal media at high pressures exceeding 100 Pa, especially at temperatures exceeding 550°C. This significantly expands the range of applications for mechanical seal devices equipped with bellows. In particular, mechanical seal devices with a combined preload / seal device can also be used for gas sealing in gas turbines, gas pipeline compressors, etc.
[0007] The value of the first preload force F1 of the bellows is preferably always smaller than the value of the second preload force F2, so that the bellows can be optimized with respect to sealing properties, while on the other hand the desired preload force of the mechanical seal can be achieved with a relatively simple design of the spring device.
[0008] The spring device is particularly preferably a spring element (negative spring) with a negative slope at the operating point A, and preferably comprises at least one disc spring, at least one cylindrical spring or other spring element with a negative slope at the operating point A. However, the spring device may also comprise several disc springs, which are preferably each connected to one fold of the bellows.
[0009] More preferably, the spring characteristic FK0 of the combined preload / seal device has a maximum displacement range B of the mechanical seal, which defines the maximum axial displacement path of the mechanical seal. Within said displacement range B, the maximum force fluctuation of the resultant force is within a range of ±10% of the force Fx at the operating point A of the spring characteristic FK0. This ensures that the spring characteristic FK0 is as flat as possible in the region around the operating point A, and particularly preferably extends as flat as possible around the inflection point A.
[0010] Particularly preferably, the combined preload and seal device is a pre-mounted unit comprising a bellows and a spring device.
[0011] In this case, the spring device is particularly preferably fixed directly to the bellows. For example, in the case of a metal bellows, the spring device can be fixed to the metal bellows by a welding or soldering process. In this case, it is particularly preferred that the spring device is fixed to the fold end region of the fold of the bellows.
[0012] According to another embodiment of the invention, the spring device and the bellows are interconnected by a connecting piece, which is preferably a ring disc to which the spring device and the bellows are fastened together.
[0013] More preferably, the connecting piece between the spring device and the bellows is a sleeve with a radially inward flange and a radially outward flange, in which case the bellows is arranged on one of the flanges and the spring device on the other, which allows for a very compact design that can also be provided as a pre-mounted unit.
[0014] More preferably, the spring device is arranged outside the bellows, and particularly preferably, in this case the spring device is arranged entirely radially outside the bellows.
[0015] According to another embodiment of the invention, the spring device is arranged inside the bellows. Particularly preferably, the spring device is arranged entirely radially inside the bellows, which allows a particularly compact design of the mechanical sealing device to be realized.
[0016] Preferably, the spring device is arranged outside the medium to be sealed.
[0017] The mechanical seal device is preferably a gas seal for sealing a gaseous medium, in which case the gaseous medium is preferably carbon dioxide or natural gas. [Brief explanation of the drawings]
[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which: [Figure 1] 1 is a schematic cross-sectional view of a mechanical seal according to a first embodiment of the invention. [Figure 2] 2 is a simplified perspective view of a combined preload / seal device of the mechanical seal device of FIG. 1. FIG. [Figure 3] 2 is a simplified graph of the spring force F on path X for the spring characteristics of the combined preload / seal device of FIG. 1. [Figure 4] FIG. 4 is a schematic cross-sectional view of a mechanical seal device according to a second embodiment of the present invention. [Figure 5]FIG. 4 is a schematic cross-sectional view of a mechanical seal device according to a third embodiment of the present invention. [Figure 6] FIG. 10 is a schematic cross-sectional view of a mechanical seal device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0019] A mechanical seal device 1 according to a first preferred embodiment of the present invention will be described in detail below with reference to FIGS.
[0020] 1, the mechanical seal device 1 includes a mechanical seal 2 having a rotary slide ring 3 and a stationary slide ring 4. A seal gap 5 is defined between a sliding surface 3a of the rotary slide ring 3 and a sliding surface 4a of the stationary slide ring 4.
[0021] In this case, the mechanical seal device 2 seals the product region 10 from the atmosphere region 11 on the shaft 8 .
[0022] The mechanical seal device 1 further includes a combined preload and seal device 6. The preload and seal device 6 is shown in detail in FIG.
[0023] The combined preload / seal device 6 includes a bellows 60 and a spring device 61. The spring device 61 includes a plurality of disc springs 62.
[0024] XX indicates the axial direction of the mechanical seal device 1.
[0025] The bellows 60 has a first preload force F1 in the first axial direction X1. The spring device 61 has a second preload force F2 in the second axial direction X2. As can be seen from FIGS. 1 and 2, in this case, the first axial direction and the second axial direction are opposite to each other. Thus, the bellows 60 fixed to the rear surface of the fixed slide ring 4 applies the first preload force F1 in the direction of the mechanical seal, and the second preload force F2 of the spring device 61 acts opposite to this. In this case, the first preload force F1 is greater than the second preload force F2 in order to preload the sliding surfaces 3a, 4a in the directions facing each other in the seal gap 5.
[0026] The spring device 61 comprises a plurality of identical spring elements 62 connected to one another. However, the individual spring elements 62 can also be fixed separately to the housing 9 and the bellows 60. The spring elements 62 are configured as double parallel disc springs and are arranged in an annular fashion along the periphery of the folds of the bellows 60. In either case, the spring elements 62 are fixed to the ends 60a of the folds of the bellows 60.
[0027] As a result, the absolute values of the first and second preload forces are different, and the resultant preload force F0 of the combined preload / seal device 6 is generated so as to act in a direction toward the mechanical seal 2. In this case, the bellows 60 particularly seals the product area 10 at the fixed slide ring 4, and the bellows 60 connects the rear surface 4b of the fixed slide ring 4 to the housing 9.
[0028] The spring device 61 partially compensates for the first preload force F1 with a smaller preload force F2.
[0029] The diagram of FIG. 3 again shows a schematic of the configuration of the preload force F0 of the mechanical seal 2. In this case, FIG. 3 shows the spring force F over the path X. The line FK1 is the spring characteristic of the bellows 60, and the line FK2 is the spring characteristic of the spring device 61. In this case, the spring characteristic FK1 of the bellows is linear, and the spring characteristic FK2 of the spring device is sinusoidal. The sum of the two spring characteristics FK1 and FK2 gives the spring characteristic FK0 that defines the axial preload of the mechanical seal 2. In this case, at operating point A, the preload force of the mechanical seal 2 is positive and has a value Fx, and the fixed slide ring 4 is pressed against the rotating slide ring 3. In this case, the spring device 61 is a spring element (negative spring) that has a negative slope at operating point A.
[0030] As can be further seen from Figure 3, the combined spring characteristic FK0 of the preload-sealing device 6 near operating point A is very flat. Figure 3 also shows the maximum displacement range B of the mechanical seal 2 around operating point A. This range defines the maximum axial displacement path of the mechanical seal 2. In this case, axial displacement of the mechanical seal components due to pressure shocks or other factors may occur during operation, but the sealing capability of the mechanical seal device must still be ensured. Within the maximum displacement range B of the mechanical seal, the maximum force fluctuation of the combined force of the two spring systems—the bellows 60 and the spring device 61—is within ±10% of the force Fx at operating point A of the spring characteristic FK0 (see Figure 3). This ensures excellent axial mobility of the fixed slide ring 4, particularly in terms of reliably containing and absorbing shocks or other factors that may cause axial displacement of the mechanical seal device components during operation. The flat spring characteristic FK0 in the region of operating point A allows for a quick return to the starting position shown in Figure 1 after deflection. In this way, by combining the two spring systems, it is possible to achieve a nearly horizontal spring characteristic FK0 of the combined preload / seal device 6 at the operating point A.
[0031] The bellows 60 is preferably made of metal. This allows the mechanical seal device 1 to withstand extremely high temperatures exceeding 550°C and temperatures of 200 x 10 5This makes it possible to use it as a gas seal that can be used at extremely high pressures exceeding Pa.
[0032] Thus, the present invention enables a mechanical seal device that allows for such use of bellows that was previously not possible due to pressure, material strength, chemical compatibility, and / or temperature. In particular, when using metallic bellows, the present invention allows for the mobility of the rigid bellows to be compensated for by an additional integral spring device 61. Furthermore, the mechanical seal device 1 according to the present invention can operate substantially without wear while still providing the required leak tightness.
[0033] The spring device 61 is arranged entirely radially outside the bellows 60. This allows for a particularly compact design. Furthermore, the combined preload and seal device 6 is provided as a pre-mounted unit and can be easily mounted on the mechanical seal device 1 without much effort.
[0034] A further mechanical seal device 1 will be described below with reference to FIGS. 4 to 6, in which identical or functionally identical parts are given the same reference numerals as in the first embodiment.
[0035] FIG. 4 shows a mechanical seal device 1 according to a second embodiment of the present invention. The combined preload and seal device 6 of the second embodiment further includes a connecting part 7 in addition to a bellows 60 and a spring device 61. The connecting part 7 connects the bellows 60 to the spring device 61. In this embodiment, the connecting part 7 is a ring disc 70. As can be seen from FIG. 4, both the axial end of the bellows 60 and the axial end of the spring device 61 are disposed on the ring disc 70. Preferably, the bellows 60 and the spring device 61 are fixed to the ring disc 70 by welded joints. In this case, the other ends of the spring device 61 and the bellows 60 are supported by the housing 9.
[0036] Furthermore, in the second embodiment, the second preload force F2 is directed towards the mechanical seal 2 and the first preload force F1 is directed away from the mechanical seal 2. In this case, the second preload force F2 is greater than the first preload force F1, and the resultant combined preload force F0 is directed towards the mechanical seal 2. In the second embodiment, the spring device comprises a plurality of smaller cylindrical springs arranged around the outer periphery of the bellows 60. In this case, the spring device 61 is generally positioned radially outward of the bellows 60.
[0037] FIG. 5 shows a mechanical seal device 1 according to a third embodiment of the present invention. The third embodiment substantially corresponds to the second embodiment, except for the configuration of the connecting piece 7 connecting the bellows 60 to the spring device 61. As shown in FIG. 5, the connecting piece 7 of the third embodiment is a sleeve 71 having a radially inward flange 71a and a radially outward flange 71b. In this case, the bellows 60 is fixed to the radially inward flange 71a. The spring device 61 is fixed to the radially outward flange 71b. This also results in a very compact design in which the spring device 61 is entirely arranged radially outside the bellows 60. Furthermore, the housing 9 is also provided with a stopper 90 for supporting the spring device 61.
[0038] 6 shows a mechanical seal device 1 according to a fourth embodiment of the present invention. In contrast to the previous embodiments, in the fourth embodiment the spring device 61 is arranged entirely inside the bellows 60. As in the two previous embodiments, the combined preload and seal device 6 comprises, in addition to the bellows 60 and the spring device 61, a connecting part 7, which is again provided as a ring disc 70. In this case, the spring device 61 and the bellows 60 are each fixed at one end to the ring disc 70. The other ends of the bellows 60 and the spring device 61 are supported by the housing 9.
[0039] It should be noted that in all the embodiments, the ratio of the preload forces F1 and F2 of the combined preload-seal device 6 may be reversed in each case. That is, the magnitude and direction of the first preload force F1 of the bellows 60 and the second preload force F2 of the spring device 61 may be selected arbitrarily, as long as the resultant preload force F0 is directed toward the mechanical seal 2. Furthermore, the bellows 60 may be made of a flexible material such as rubber. In addition to a disc spring, the spring device 61 may be made of multiple cylindrical springs arranged along the outer periphery of the bellows 60, or even a single cylindrical spring arranged around or inside the bellows 60. [Explanation of symbols]
[0040] 1 Mechanical seal device 2 Mechanical seal 3 Rotating Slide Ring 3a Sliding surface 4 Fixed slide ring 4a Sliding surface 4b Rear 5 Seal gap 6. Combined preload and seal device 7 Connecting parts 8 shafts 9. Housing 10 product areas 11 Atmospheric Region 60 Bellows 60a Bellows fold end 61 Spring device 62 Spring elements 70 Ring Disc 71 Sleeve 71a Radial inward flange 71b Radial outward flange 90 Stopper A Operating point of preload and sealing device 6 B Axial displacement range F0 Combined preload force F1 Bellows first preload F2 Second preload force of spring device Fx Force at the operating point FK0 composite spring characteristics FK1 Bellows spring characteristics Spring characteristics of FK2 spring device XX Axial direction X1 1st axis direction X2 2nd axis direction
Claims
1. a mechanical seal (2) having a rotating slide ring (3) and a fixed slide ring (4), wherein a seal gap (5) is defined between a sliding surface (3 a) of the rotating slide ring (3) and a sliding surface (4 a) of the fixed slide ring (4); a combined preload / seal device (6) for sealing one of the two slide rings in the axial direction (X-X) and applying a preload; The preload and seal device (6) comprises a circumferentially closed bellows (60) and a spring device (61); The bellows (60) is configured as a secondary sealing element of the mechanical seal and seals against one of the two slide rings; The bellows (60) applies a first preload force F1 in a first axial direction X1, and the spring device (61) applies a second preload force F2 in a second axial direction X2 opposite to the first axial direction X1. The absolute values of the first preload force F1 and the second preload force F2 are different so that a resultant force F0 of the preload / seal device (6) acts in the direction of the slide rings (3, 4) due to preload.
2. 2. The mechanical seal device according to claim 1, wherein a value of the first preload force F1 of the bellows (60) is smaller than a value of the second preload force F2 of the spring device (61).
3. The spring characteristic FK0 of the preload / seal device (6) at the operating point A of the preload / seal device (6) indicates an inflection point, 3. The mechanical seal device according to claim 1, wherein the spring device (61) is a spring system having a negative slope at the operating point.
4. 4. The mechanical seal device according to claim 3, wherein the spring characteristic FK0 of the combined preload / seal device (6) is a maximum displacement range B of the mechanical seal (2) that defines a maximum axial displacement path of the mechanical seal (2), and has a maximum force fluctuation of the resultant force within a range of ±10% of the force Fx at the operating point A of the spring characteristic FK0.
5. The mechanical seal device according to any one of claims 1 to 4, wherein the preload and seal device (6) is a pre-mounted unit comprising the bellows (60) and the spring device (61).
6. 6. The mechanical seal device according to claim 5, wherein the spring device (61) is directly fixed to the bellows (61).
7. 6. The mechanical seal device according to claim 5, wherein the spring device (61) is connected to the bellows (61) via a connecting piece (7).
8. 8. The mechanical seal device according to claim 7, wherein the connecting part (7) is a ring disk (70) or a sleeve having a radially inward flange (71a) and a radially outward flange (71b).
9. The mechanical seal device according to any one of claims 1 to 8, wherein the spring device (61) is arranged outside the bellows.
10. The mechanical seal device of claim 9, wherein the spring device is disposed generally radially outward of the bellows (60).
11. The mechanical seal device according to any one of claims 1 to 8, wherein the spring device (61) is arranged inside the bellows.
12. 12. The mechanical seal device of claim 11, wherein the spring device (61) is disposed entirely inside the bellows (60).
13. The mechanical seal device according to any one of claims 1 to 12, configured as a gas seal.
Citation Information
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