Mechanical seal arrangement with improved cooling performance

Description

[0001] The present invention relates to a mechanical seal arrangement with improved cooling behavior and in particular to a stationary seal ring which is - at least partially - surrounded by fluid on an inner circumference and on an outer circumference.

[0002] Mechanical seal assemblies are known in various designs from the prior art. During operation, mechanical seal assemblies often use so-called barrier fluid systems, which, in addition to lubrication, also carry out heat dissipation at the mechanical seals. The cooling of the mechanical seal has the particular task of preventing overheating during operation and potential consequential damage to the mechanical seal assembly. However, for sufficient cooling, a certain flow rate must be enabled in the area of ​​the mechanical seal. The barrier or cooling fluid is usually fed into the area of ​​the mechanical seal through an inlet and discharged via an outlet. For this purpose, it is known to use, for example, so-called conveyor sleeves, which support the movement of the cooling fluid from the inlet to the outlet through their rotation.However, there is a fundamental need for continuous improvement of cooling performance in order to further improve the service life and performance of a mechanical seal arrangement.

[0003] Furthermore, a mechanical seal arrangement according to the preamble of claim 1 is known from EP 0 790 446 A1.

[0004] It is therefore an object of the present invention to provide a mechanical seal arrangement which enables an improved cooling effect with a simple structure and simple, cost-effective manufacture.

[0005] This object is achieved by a mechanical seal arrangement having the features of claim 1. The subclaims show preferred developments of the invention.

[0006] The mechanical seal assembly according to the invention with the features of claim 1 has the advantage that an improved cooling effect is enabled. This can improve the service life and, in particular, also the wear behavior of the mechanical seal assembly. In particular, a combination of several modifications can achieve a significantly improved conveying capacity and thus improved cooling. This is achieved according to the invention in that the mechanical seal assembly has a first and a second mechanical seal. Each of the mechanical seals has a rotating and a stationary seal ring, which define a sealing gap between them. Furthermore, a housing with an inlet and an outlet for a cooling liquid is provided.The mechanical seal arrangement further comprises a rotating conveyor sleeve which is connected to the first rotating slide ring of the first mechanical seal and the second rotating slide ring of the second mechanical seal. The conveyor sleeve has a plurality of conveyor grooves on its outer circumference so that cooling fluid is moved when the conveyor sleeve rotates. The first stationary slide ring is arranged radially outside the conveyor sleeve. An inner circumference of the first stationary slide ring of the first mechanical seal is arranged eccentrically to an outer circumference of the conveyor sleeve. This creates a circumferential eccentric gap between the outer circumference of the conveyor sleeve and the inner circumference of the first stationary slide ring, through which the cooling fluid is conveyed. This significantly increases the conveying speed of the conveyed fluid.Furthermore, the first stationary seal ring has a slot on a rear side facing away from the first sealing gap and a widening recess on the inner circumference. The recess opens into the slot. This feature significantly improves the flow of the pumped fluid into the outlet, thus significantly improving the efficiency of the pump sleeve.

[0007] Furthermore, an annular gap is formed adjacent to the rear side of the first stationary seal ring between a stationary component, for example, a housing, and the outer circumference of the stationary seal ring. This allows for conveyance on the side of the first seal ring facing away from the first sealing gap, both on the inner circumference of the stationary seal ring and on the outer circumference of the stationary seal ring. This enables cooling of the stationary seal ring from two circumferential sides, i.e., inside and outside, in the area of ​​the free end of the stationary seal ring located on the rear side.

[0008] Furthermore, adjacent to the rear side of the first stationary seal ring, a second, widening recess is formed on the housing, which opens into the outlet. This also opens the annular gap to the outlet, allowing for improved fluid flow from the annular gap into the outlet. This further improves the efficiency of the cooling fluid pumping.

[0009] According to a further preferred embodiment of the invention, the rotating conveyor sleeve is designed such that the conveyor sleeve has a receiving area for securing the first rotating slide ring of the first mechanical seal. The receiving area is thus designed such that the first rotating slide ring is at least partially encompassed. This enables simple and secure fixing of the first rotating slide ring to the conveyor sleeve.

[0010] Particularly preferred is a number n of conveying grooves in the conveying sleeve 12 ≤ n, and in particular in a range between 18 ≤ n ≤ 24. The conveying grooves preferably run parallel to a central axis of the mechanical seal arrangement. This makes the manufacture of the conveying grooves particularly simple.

[0011] Preferably, the rear side of the first stationary seal ring of the first mechanical seal is located radially inside the outlet. Thus, the rear side of the first stationary seal ring is arranged below the outlet, so that the rear side of the first stationary seal ring is continuously surrounded by cooling fluid.

[0012] Further preferably, a center line of the outlet and the rear side of the first stationary seal ring lie in a common plane perpendicular to the axial direction XX. Thus, a shadow projection of the outlet onto the first stationary seal ring is such that the shadow lies partially on the first stationary seal ring. Particularly preferably, the rear side of the first stationary seal ring is also located in the center of the inlet.

[0013] According to a further preferred embodiment of the invention, the inlet and outlet are arranged in the housing in the axial direction of the mechanical seal arrangement between the first and second mechanical seals. Particularly preferably, the inlet and outlet are located opposite each other at 180° along the circumference of the mechanical seal arrangement. Furthermore, a diameter of the inlet is preferably equal to a diameter of the outlet.

[0014] A particularly aerodynamically favorable arrangement is achieved if the inlet, the outlet, and the first and second slots are preferably arranged coaxially with one another. Further preferably, the diameters of the inlet and outlet, and the width of the first and second slots, are the same.

[0015] In order to achieve a particularly good cooling effect on the mechanical seals, a volume of the second recess in the housing is preferably larger than a volume of the first recess of the first stationary seal ring.

[0016] Further preferably, the annular gap on the outer circumference of the first stationary sliding ring has a constant gap width over the circumference.

[0017] Preferably, the eccentricity between the conveying sleeve and the first stationary seal ring lies on a horizontal line of the mechanical seal arrangement. Alternatively, the eccentricity lies on a straight line that is at a 45° angle to the horizontal and a vertical line.

[0018] To further improve the cooling effect and increase the efficiency of the delivery sleeve, a second slot and a third, tapered recess are preferably provided on the first stationary seal ring on the rear side facing away from the sealing gap. The third, tapered recess tapers from the second slot toward the eccentric gap. This allows for better fluid flow into the eccentric gap, which can further improve the delivery capacity and thus the cooling effect.

[0019] Further preferably, a fourth, tapered recess is formed on the housing, which tapers from the inlet toward the annular gap between the housing and the outer circumference of the first stationary seal ring. This can also improve the pumping capacity and thus the cooling performance of the arrangement.

[0020] If the third and fourth recesses are provided on the second slot, the mechanical seal arrangement can also be operated independently of the direction of rotation.

[0021] Particularly preferably, the mechanical seal assembly is a pre-assembled unit, so that the mechanical seal assembly can be installed as a cartridge on the shaft to be sealed. This can prevent errors, especially during on-site assembly.

[0022] A preferred embodiment of the invention is described in detail below with reference to the accompanying drawing. In the drawing: Fig. 1 is a schematic sectional view of a mechanical seal arrangement according to a first preferred embodiment of the invention, Fig. 2 is a schematic cross-sectional view along the line II-II of Fig. 1 , Fig. 3 a schematic, perspective, enlarged sectional view of the mechanical seal of Fig. 1 , Fig. 4 a schematic, enlarged cross-sectional view of the mechanical seal arrangement of Fig. 1 in the area of ​​the outlet, Fig. 5 a schematic, perspective view of a conveyor sleeve of the mechanical seal arrangement of Fig. 1 , and Fig. 6 is a schematic cross-sectional view of a mechanical seal arrangement according to a second preferred embodiment of the invention.

[0023] The following is based on the Fig. 1 bis 5 a mechanical seal arrangement 1 according to a first preferred embodiment of the invention is described in detail.

[0024] As from Fig. 1 As can be seen, the mechanical seal arrangement 1 comprises a first mechanical seal 2 and a second mechanical seal 3. The two mechanical seals 2, 3 are arranged in series in the axial direction XX of the mechanical seal arrangement.

[0025] The mechanical seal arrangement 1 seals a shaft 10.

[0026] The first mechanical seal 2 comprises a first stationary seal ring 21, a first rotating seal ring 22, and a sealing gap 20 arranged between the first stationary seal ring 21 and the first rotating seal ring 22. The second mechanical seal 3 comprises a second stationary seal ring 31, a second rotating seal ring 32, and a sealing gap 30 between the second stationary seal ring 31 and the second rotating seal ring 32.

[0027] Furthermore, the mechanical seal assembly 1 comprises a housing 4 on which the stationary seal rings 21, 31 are arranged. As further shown in Fig. 1 As can be seen, an inlet 40 and an outlet 41 for a cooling liquid are provided in the housing 4. In this exemplary embodiment, the inlet and outlet are cylindrical and arranged 180° opposite each other on the mechanical seal assembly 1. As a result, the center lines 60 of the inlet 40 and outlet 41 lie on a common straight line.

[0028] The mechanical seal assembly 1 further comprises a rotating conveyor sleeve 5. The conveyor sleeve 5 is connected to the first rotating seal ring 22 and the second rotating seal ring 32. The first rotating seal ring 22 is partially surrounded by the conveyor sleeve 5 at a receiving area 51 of the conveyor sleeve 5. The second rotating seal ring 32 is fixed to the conveyor sleeve 5 by means of a seal ring carrier 33.

[0029] The conveyor sleeve 5 is made in detail from Fig. 5 As shown in Fig. 5 As shown, the conveyor sleeve 5 has a plurality of conveyor grooves 50, which are arranged on an outer circumference 50a of the conveyor sleeve 5. The conveyor grooves 5 are formed parallel to the axial direction XX. Preferably, a number n of the conveyor grooves 50 is greater than or equal to 12 and in particular between 18 and 24 conveyor grooves. Fig. 5 Furthermore, the receiving area 51 of the conveyor sleeve 5 is shown again in detail, to which the first rotating slide ring 21 is fixed.

[0030] As is particularly evident from Fig. 2 As can be seen, the first stationary sliding ring 21 has an inner circumference 21a, which is arranged eccentrically to an outer circumference 50a of the conveyor sleeve 5. This results in a circumferential eccentric gap 6, which is formed between the conveyor sleeve 5 and the first stationary sliding ring 21 on its rear side 21b facing away from the sealing gap 20 (cf. Fig. 3 ).

[0031] As further stated in particular Fig. 2 As can be seen, the annular eccentric gap 6 tapers from the inlet 40 to the outlet 41. In contrast, an annular gap 7 between the first stationary slide ring 21 and the housing 4 remains constant (cf. Fig. 2 ). An eccentricity E between the conveyor sleeve 5 and the first stationary seal ring lies on a straight line G, which is at an angle of 45° to a horizontal line 15 and a vertical line 16 of the mechanical seal arrangement 1.

[0032] How further from the Fig. 2 and 3 As can be seen, a first slot 9 and a second slot 8 are formed on the rear side 21b of the first stationary sliding ring 21. The first slot 9 is arranged coaxially with the outlet 41 and the second slot 8 is arranged coaxially with the inlet 40 (cf. Fig. 2 ).

[0033] These slots 8, 9 have only a relatively small depth T in the axial direction XX (cf. Fig. 1 ), so that the first stationary sliding ring 21 maintains its basic stability.

[0034] The center lines 60 of the inlet 40 and the outlet 41 lie with the rear side 21b of the first stationary seal ring in a common plane 61 which is perpendicular to the axial direction XX (cf. Fig. 1 ).

[0035] As from Fig. 2 As can be seen, cooling fluid flows from the inlet 40 on the one hand into the annular gap 7 and on the other hand through the second slot 8 into the circumferential eccentric gap 6. By the rotation of the conveyor sleeve 5 (arrow A in Fig. 2 ), the cooling liquid is conveyed in the annular gap 7 (arrows B) as well as in the circumferential eccentric gap 6 (arrows C) in the direction of the outlet 41.

[0036] As can be seen from the Fig. 2 and 3As can be seen, an expanding recess 11 is formed on the first stationary seal ring 21. A second expanding recess 12 is formed on the housing 4 at the outlet of the annular gap 7 to the outlet 41. This significantly improves the flow behavior of the fluid as it exits the annular gap 7 or the annular eccentric gap 6 into the outlet 41, thereby significantly improving the efficiency of pumping the cooling fluid.

[0037] The circumferential eccentric gap 6 is thus formed between an inner circumference 21a of the first stationary sliding ring 21 and the outer circumference 50a of the conveyor sleeve 5. Fig. 4 shows again in detail the exit of the fluid flows (arrows B, C) from the annular gap 7 or the circumferential eccentric gap 6. The two widening recesses 11, 12 guide the cooling liquid into the outlet 41 with as little loss as possible, so that in conjunction with the large number of conveying grooves 50 in the conveying sleeve 5, a significantly improved efficiency in conveying can be achieved.

[0038] The following is based on reference to Fig. 6 A mechanical seal assembly according to a second preferred embodiment of the invention is described in detail. Identical or functionally identical parts are designated by the same reference numerals as in the first embodiment.

[0039] As from Fig. 6 As can be seen, in contrast to the first embodiment, in the second embodiment, a flow improvement is also carried out at the inlet 40 of the mechanical seal arrangement 1. Here, a third, tapered recess 13 is provided on the rear side 21b of the first stationary seal ring 21 facing away from the sealing gap and a fourth, tapered recess 14 is formed in the housing 4. As shown in Fig. 6 shown, a second slot 8 is formed on the rear side 21b of the first stationary slide ring 21. This enables a flow-optimized supply of the fluid from the inlet 40. The fluid flows via the third, tapered recess 13 into the eccentric gap 6 and from the inlet 40 via the fourth, tapered recess 14 into the annular gap 7. A further advantage of this design is that the mechanical seal arrangement is independent of the direction of rotation. This means that if the direction of rotation A is reversed, the outlet 41 becomes the inlet and the inlet 40 becomes the outlet. Since the first, second, third and fourth recesses 11, 12, 13, 14 are provided as mirror images on the horizontal line 15, this can be achieved without any problems.Furthermore, the eccentricity E is also different compared to the first embodiment in that the eccentricity E was achieved by a shift on the horizontal 15 from the center (center axis XX). The eccentricity E thus implemented results in the same cooling performance of the mechanical seal assembly 1, regardless of the direction of rotation.

[0040] Otherwise, this embodiment corresponds to the previous embodiment, so that reference can be made to the description given there.

[0041] Thus, according to the invention, a mechanical seal arrangement 1 can be provided which enables a significantly improved cooling effect by providing a combination of several measures on the mechanical seal arrangement. In particular, the provision of the conveying sleeve 5 with conveying grooves 50 and the first and second widening recesses 11, 12 on the housing and on the first stationary seal ring 21, respectively, significantly improve the cooling behavior of the mechanical seal arrangement. A further improvement is achieved by the provision of the third and fourth recesses 13, 14, whereby the mechanical seal arrangement can also be operated in both directions of rotation. In particular, the improved cooling effect of the mechanical seal arrangement enables it to be used to seal media that may have high to very high temperatures without damaging the mechanical seal arrangement. Bezugszeichenliste

[0042] 1 Mechanical seal arrangement 2 First mechanical seal 3 Second mechanical seal 4 Casing 5 Conveyor sleeve 6 Annular eccentric gap 7 Annular gap 8 Second slot 9 First slot 10 Shaft 11 First widening recess on the first stationary seal ring 12 Second widening recess on the casing 13 Third tapered recess 14 Fourth tapered recess 15 Horizontal 16 Vertical 20 First sealing gap 21 First stationary seal ring 21a Inner circumference of the first stationary seal ring 21b Rear of the first stationary seal ring 22 First rotating seal ring 30 Sealing gap 31 Second stationary seal ring 32 Second rotating seal ring 33 Seal ring carrier 40 Inlet 41 Outlet 50 Conveyor grooves 50a Outer circumference of the conveying sleeve 51Receiving area on the delivery sleeve 60Centerline of inlet and outlet 61Plane EExcentricity G45° straight line TTepth of the first and second slot X-XAxial direction of the mechanical seal arrangement

Claims

1. A mechanical seal arrangement comprising: - a first mechanical seal (2) comprising a first rotating sliding ring (22) and a first stationary sliding ring (21) defining a first sealing gap (20) therebetween, - a second mechanical seal (3) having a second rotating sliding ring (22) and a second stationary sliding ring (32) defining a second seal gap (30) therebetween, - a housing (4) with an inlet (40) and an outlet (41) for a cooling liquid, - a rotating conveying sleeve (5) which is joined to the first rotating sliding ring (22) and the second rotating sliding ring (32) - said conveying sleeve (5) having a plurality of conveying grooves (50) on its outer circumference, - wherein the first stationary sliding ring (21) is arranged radially outside the conveying sleeve (5) and has an inner circumference (21a) which is eccentric to an outer circumference (50a) of the conveying sleeve (5) so that a circumferential eccentric gap (6) is formed between the outer circumference (50a) of the conveying sleeve (5) and the inner circumference (21a) of the first stationary sliding ring (21), characterized in in that - the first stationary sliding ring (21), on a rear side (21b) facing away from the first sealing gap (20), has a first slot (9) directed towards the outlet (41) and a first widening recess (11) on the inner circumference (21a), which recess opens into the first slot (9), - wherein an annular gap (7) is formed adjacent to the rear side (21b) of the first stationary sliding ring (21) between the housing (4) and the outer circumference of the first stationary sliding ring (21), and. - wherein a second widening recess (12) is formed on the housing (4), which recess opens from the annular gap (7) into the outlet (41).

2. The mechanical seal arrangement according to claim 1, wherein the conveying sleeve (5) has a receiving region (51) for fixing the first rotating sliding ring (22).

3. The mechanical seal arrangement according to one of the preceding claims, wherein a number n of the conveying grooves (50) of the conveying sleeve (5) is greater than or equal to 12 and in particular is between 18 ≤ n ≤ 24.

4. The mechanical seal arrangement according to one of the preceding claims, wherein the rear side (21b) of the first stationary sliding ring (21) is located radially inside the outlet (41).

5. The mechanical seal arrangement according to claim 4, wherein a center line of the outlet (41) and the back side (21b) of the first stationary sliding ring (21) lie in a common plane (61) which is perpendicular to the axial direction (X-X) of the mechanical seal arrangement.

6. The mechanical seal arrangement according to one of the preceding claims, wherein the inlet (40) and the outlet (41) are arranged in the axial direction (X-X) of the mechanical seal arrangement between the first mechanical seal (2) and the second mechanical seal (3).

7. The mechanical seal arrangement according to one of the preceding claims, wherein the inlet (40) and the outlet (41) are opposite each other by 180° at the circumference of the mechanical seal arrangement.

8. The mechanical seal arrangement according to one of the preceding claims, wherein a volume of the second widening recess (12) on the housing (4) is larger than a volume of the first widening recess (11) on the first stationary sliding ring (21).

9. The mechanical seal arrangement according to one of the preceding claims, wherein the annular gap (7) has a constant gap width along its circumference.

10. The mechanical seal arrangement according to one of the preceding claims, wherein the eccentricity (E) between the conveying sleeve (5) and the first stationary sliding ring (21) is located on a horizontal line (15) of the mechanical seal arrangement.

11. The mechanical seal arrangement according to one of the preceding claims, wherein the first stationary sliding ring (21) has a second slot (8) on the rear side (21b) facing away from the sealing gap (20) and a third, tapered recess (13) on the inner circumference, which, starting from the second slot (8), tapers in the direction of the eccentric gap (6).

12. The mechanical seal arrangement according to claim 11, wherein a fourth tapered recess (14) is formed on the housing, which tapers from the inlet (40) into the annular gap (7).

13. The mechanical seal arrangement according to one of the preceding claims, wherein the mechanical seal arrangement is a pre-assemblable assembly.