A wind turbine unit torsion cable protection device

Abstract

The application provides a wind turbine torsion cable protection device, which comprises an outer cylinder, an inner ring, a fixed clamp and a ball. The inner ring, the fixed clamp and the ball are arranged in the outer cylinder in a circular tube shape. The fixed clamp is provided with a plurality of installation rings arranged in the inner ring. The ball is provided with a plurality of rotatable installations arranged at the outermost end of the inner ring or the fixed clamp, so that the ball is in abutment with the outer cylinder. The inner ring moves up and down along the inner wall of the outer cylinder or rotates relative to the outer cylinder under the limiting action of the ball. A plurality of torsion cable protection devices are arranged according to the tower height of the wind turbine. Adjacent torsion cable protection devices are spaced at a certain distance. The outer cylinder of the torsion cable protection device is installed on the inner wall of the tower of the wind turbine. The torsion cable can be fixed on the inner ring through the fixed clamp and can realize torsion and up-and-down movement through the ball, so as to avoid direct contact between the torsion cable and the outer cylinder or the tower, thereby avoiding abrasion and protecting the torsion cable. In addition, the design scheme has the advantages of simple structure, low manufacturing cost and certain cost advantage.

Description

Technical Field

[0001] This application relates to the field of wind turbine components, and more particularly to a wind turbine cable torsion protection device. Background Technology

[0002] Because wind direction changes, the rotor of a wind turbine needs to rotate and adjust to follow the wind direction in order to obtain greater power. The rotor is installed in the nacelle, so the nacelle also needs to rotate. The nacelle has a torsion cable. The upper end of the torsion cable is fixed to the nacelle and rotates with the nacelle, while the lower end of the torsion cable is fixed. In addition, the wind turbine has a large power output, so the torsion cable is relatively thick. It cannot be twisted at a large angle over a short distance. The torsional deformation needs to be gradually distributed throughout the torsion cable. That is, when the upper end of the torsion cable rotates, the rotation angle of the entire torsion cable gradually decreases to zero from top to bottom. In other words, the middle area of ​​the torsion cable rotates. If this rotation is not restricted, the torsion cable may be damaged if it rubs against other objects during the rotation.

[0003] Chinese patent application CN110397564B, entitled "Wind Twist Cable Protection Device," discloses a wind turbine cable protection device. This device protects the twisted cable inside the tower of a wind turbine and includes: a cable support, a first cable clamp, and second cable clamps. The cable support is installed at the bottom of the tower to support the twisted cable and allow it to pass downwards along the inner wall of the tower. One first cable clamp is installed on a tower platform plate at the bottom of the tower, holding the twisted cable and driving it to move up and down along the tower axis. Several second cable clamps are spaced apart and installed on several tower platform plates between the first cable clamp and the top of the tower, holding the twisted cable and driving it to rotate and move up and down along the tower axis. This design has a closed annular structure for the first cylinder, requiring the twisted cable to be inserted from one end, which is inconvenient for installation. Furthermore, the large-diameter structure incurs high time and cost for machining the spiral groove.

[0004] Chinese patent application CN10364724 A, entitled "A Wind Turbine Generator Main Cable Twisting Device," discloses a wind turbine generator main cable twisting device. Its features include a twisting rotor, a twisting guide rail, and a connecting bracket. The twisting guide rail is an annular guide rail, connected to the wind turbine tower via the connecting bracket. The twisting rotor rotates within the annular guide rail. The rotor has a circular hole matching the size of the main cable, and the cable and bundled signal / data lines are placed within this hole. The circular hole and the main cable or bundled signal / data lines are in clearance fit. This technical solution does not consider the case of axial vertical movement of the twisted cable, only the case of cable rotation. Utility Model Content

[0005] This application provides a torsion cable protection device for wind turbine generator sets, which at least solves the problems existing in the prior art regarding torsion cable protection technology.

[0006] According to this application, a wind turbine generator cable torsion protection device is provided, including an outer cylinder, an inner ring, a fixing clamp, and balls. The inner ring, fixing clamp, and balls are disposed inside the cylindrical outer cylinder. Multiple fixing clamps are installed on the inner ring. Multiple balls are rotatably installed on the outermost end of the inner ring or the fixing clamp so that the balls abut against the outer cylinder. Under the limiting action of the balls, the inner ring moves linearly up and down along the inner wall of the outer cylinder or rotates relative to the outer cylinder.

[0007] Compared with existing technologies, the wind turbine generator cable torsion protection device of this application has the following advantages: Multiple cable twisting protection devices are installed according to the tower height of the wind turbine generator set. Adjacent cable twisting protection devices are spaced at a certain distance. The outer cylinder of the cable twisting protection device is installed on the inner wall of the wind turbine generator set tower. The cable twisting can be fixed to the inner ring by a fixing clamp and can be twisted and moved up and down by ball bearings. This avoids the cable twisting directly contacting the outer cylinder or tower to avoid wear. It allows the cable twisting to rotate freely and move up and down within a certain range. Thus, the upper end of the cable twisting can rotate 360 ​​degrees or even 720 degrees, while the lower end of the cable twisting remains fixed. In addition, the cable twisting has a certain margin for up and down movement. When the upper part of the cable twisting rotates significantly, the lower part of the cable twisting rotates slightly and moves up and down, which prevents the cable twisting from being damaged during the rotation of the nacelle and protects the cable twisting. In addition, this design scheme has a simple structure and low manufacturing cost, which has a certain cost advantage.

[0008] In one embodiment, the fixing clip includes a triangular fixing clip and a semi-circular fixing clip. The semi-circular fixing clip has a semi-circular portion, a first mounting portion, and a second mounting portion. The first mounting portion and the second mounting portion are located on both sides of the semi-circular portion. The first mounting portion has a first mounting hole, and the second mounting portion has a second mounting hole. The first mounting portion and the second mounting portion are installed to the inner ring by bolts. The triangular fixing clip has a first clamping portion, a second clamping portion, and a third mounting portion. The first clamping portion, the second clamping portion, and the third mounting portion are distributed on the three sides of an equilateral triangle. The third mounting portion has a third mounting groove and a third mounting hole. The triangular fixing clip is installed on the inner ring through the third mounting hole. The depth of the third mounting groove is greater than the thickness of the bolt head, so that the bolt head is completely embedded in the third mounting groove. Triangular clamps offer higher strength and can secure three thicker high-voltage cables, while semi-circular clamps are primarily used to secure low-voltage cables. These cables are thinner and experience less stress, and are typically encased in the same protective tube. Additionally, thinner cables can also be fitted with thicker protective tubes and installed within the triangular clamps. The third mounting slot prevents bolt heads from protruding and causing cable abrasion. Compared to semi-circular clamps, triangular clamps provide stronger clamping force and better heat dissipation, effectively securing the cables. Semi-circular clamps, on the other hand, have lower manufacturing costs, offering a cost advantage.

[0009] In one embodiment, the first clamping part is provided with a first locking part at the end away from the third mounting part, and the first locking part is provided with a first clamping hole. The second clamping part is provided with a second locking part at the end away from the third mounting part, and the second locking part is provided with a second clamping hole. Clamping bolts are provided in the first clamping hole and the second clamping hole, so that the triangular fixing clip can be more firmly fixed to the outside of the cable.

[0010] In one embodiment, the triangular fixing clamp is equipped with a ball bearing frame, which is fixed to the first clamping part or the second clamping part by clamping bolts, so that there is no need to set a separate ball bearing rod, which facilitates installation.

[0011] In one embodiment, the triangular fixing clip includes a left clip and a right clip. The left clip has a first overlapping portion, a first connecting portion, a first clamping portion, and a first locking portion. The first clamping portion has an inwardly protruding first arc-shaped limiting portion. The right clip has a second overlapping portion, a second connecting portion, a second clamping portion, and a second locking portion. The second clamping portion has an inwardly protruding second arc-shaped limiting portion. The first overlapping portion overlaps with the second overlapping portion. The first overlapping portion has a left mounting hole, and the second overlapping portion has a right mounting hole. The bolt passes through the left mounting hole and the right mounting hole to install the triangular fixing clip on the inner ring. This arrangement eliminates the need for insertion from one end of the cable, allowing direct installation at any position with a high fault tolerance.

[0012] In one embodiment, the left or right clamp is provided with a spherical ball bearing hole, and the ball bearing is installed in the spherical ball bearing hole, which facilitates installation.

[0013] In one embodiment, the inner ring is provided with a ball bearing rod, which is installed in the mounting hole of the inner ring, thus adapting to different designs and different types of wind turbine generator sets.

[0014] In one embodiment, the ball screw includes a first nut, a second nut, a screw, and a sleeve. One end of the screw is installed on the inner ring and the other end is threaded to the sleeve. The sleeve is provided with a ball seat to rotatably install the balls. The first nut locks the screw in the inner ring, and the second nut locks the screw and the sleeve in a certain relative position. In this way, the length of the ball screw can be adjusted to adapt to different cable radii.

[0015] In one embodiment, the outer cylinder includes a first half-cylinder and a second half-cylinder. The first half-cylinder and the second half-cylinder adopt the same symmetrical design. Both the first half-cylinder and the second half-cylinder are provided with a left wing plate and a right wing plate. The left wing plate and the right wing plate are provided with multiple mounting holes. This design makes installation more convenient.

[0016] In one embodiment, a retaining ring is provided at the lower end of the outer cylinder. The retaining ring has a semi-circular cross-section and is fixed to the inner wall of the outer cylinder by screws. This can confine the inner ring inside the outer cylinder and prevent accidental vibration or other factors from causing the inner ring to detach from the outer cylinder, thus affecting the rotation and vertical movement of the torsion cable.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0018] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0019] Figure 1 This paper shows a schematic diagram of the structural composition of the wind turbine generator cable torsion protection device according to Embodiment 1 of this application; Figure 2 This paper shows a schematic diagram of the installation cross-section of the wind turbine generator cable torsion protection device according to Embodiment 1 of this application; Figure 3 A schematic diagram of the semi-circular fixing clamp of the wind turbine generator cable torsion protection device according to Embodiment 1 of this application is shown; Figure 4 A schematic diagram of the triangular fixing clamp of the wind turbine generator cable torsion protection device according to Embodiment 1 of this application is shown; Figure 5 A schematic diagram of the ball bearing frame of the wind turbine generator cable torsion protection device according to Embodiment 1 of this application is shown; Figure 6 This paper shows a schematic diagram of the assembly state of the left and right clamps of the triangular fixing clamp of the wind turbine generator cable torsion protection device according to Embodiment 2 of this application; Figure 7 This diagram shows the left and right clamps of the triangular fixing clamp of the wind turbine generator cable torsion protection device according to Embodiment 2 of this application in a separated state. Figure 8 This paper shows a schematic diagram of the structural composition of the wind turbine generator cable torsion protection device according to Embodiment 3 of this application; Figure 9 This paper shows a top view of the wind turbine generator cable torsion protection device according to Embodiment 3 of this application; Figure 10 A cross-sectional schematic diagram along the direction of the ball bearing rod is shown for the wind turbine generator cable torsion protection device of Embodiment 3 of this application.

[0020] Explanation of the labels in the diagram: 1. Outer cylinder; 2. Inner ring; 3. Fixing clamp; 4. Ball bearing; 5. Ball bearing cage; 6. Ball bearing rod; 7. Retaining ring; 8. Cable; 9. Data cable; 10. First half-cylinder; 11. Second half-cylinder; 12. Left wing plate; 13. Right wing plate; 31. Triangular fixing clamp; 32. Semi-circular fixing clamp; 37. Left clamp; 38. Right clamp; 51. Bolt hole; 52. Ball bearing hole; 61. First nut; 62. Second nut; 63. Screw; 64. Sleeve; 65. Ball bearing seat; 311. First clamping part; 312. Second clamping part; 313. 314. Third mounting groove; 315. Third mounting hole; 316. Bolt head; 317. First locking part; 318. First clamping hole; 319. Second locking part; 320. Second clamping hole; 321. Semi-ring part; 322. First mounting part; 323. Second mounting part; 324. First mounting hole; 325. Second mounting hole; 371. First overlapping part; 372. First connecting part; 373. First arc-shaped limiting part; 381. Second overlapping part; 382. Second connecting part; 383. Second arc-shaped limiting part. Detailed Implementation

[0021] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Example 1: like Figure 1 and Figure 2 As shown, a wind turbine generator cable twisting protection device includes an outer cylinder 1, an inner ring 2, a fixing clamp 3, and ball bearings 4. The inner ring 2, fixing clamp 3, and ball bearings 4 are disposed inside the cylindrical outer cylinder 1. The inner ring 2 has a cylindrical structure, which reduces the weight of the inner ring 2. To ensure strength, it is made of steel and has a certain resistance to deformation. The fixing clamp 3 has multiple circumferentially distributed and installed on the outer side of the inner ring 2. The ball bearings 4 have multiple rotatable installations at the outermost end of the fixing clamp 3, so that when the inner ring 2 moves radially relative to the outer cylinder 1, the ball bearings 4 abut against the outer cylinder 1. Under the limiting action of the ball bearings 4, the inner ring 2 moves linearly up and down along the inner wall of the outer cylinder 1 or rotates relative to the outer cylinder 1. The wind turbine generator cable twisting includes a power transmission cable 8 and a data transmission cable 9, as well as cables with other functions, such as power lines providing control power.

[0023] like Figure 1 and Figure 2As shown, in one embodiment, the fixing clip 3 includes six triangular fixing clips 31 and two semi-circular fixing clips 32. The semi-circular fixing clips 32 are made of steel, with one large and one small. The triangular fixing clips 31 are made of aluminum alloy, or they can be made of cast iron.

[0024] like Figure 3 As shown, the semi-circular fixing clip 32 has an arc-shaped semi-circular portion 321, a first mounting portion 322, and a second mounting portion 323. The first mounting portion 322 and the second mounting portion 323 are located on both sides of the semi-circular portion 321. The first mounting portion 322 has a first mounting hole 324, and the second mounting portion 323 has a second mounting hole 325. The first mounting portion 322 and the second mounting portion 323 are arranged in an arc shape to match the inner ring 2 and are installed to the inner ring 2 by bolts. Figure 2 As shown, the semi-circular fixing clip 32 can install a single data cable 9 or multiple auxiliary function cables.

[0025] like Figure 2 and Figure 4 As shown, the triangular fixing clip 31 has a first clamping part 311, a second clamping part 312, and a third mounting part 313. The first clamping part 311, the second clamping part 312, and the third mounting part 313 are distributed on the three sides of the equilateral triangle. The triangular fixing clip 31 can install three cables 8 located at the three vertices of the equilateral triangle. The third mounting part 313 has a third mounting groove 314 and a third mounting hole 315. The triangular fixing clip 31 is installed on the inner ring 2 through the third mounting hole 315. The depth of the third mounting groove 314 is greater than the thickness of the bolt head 316, so that the bolt head 316 is completely embedded in the third mounting groove 314.

[0026] like Figure 4 As shown, in one embodiment, the first clamping part 311 is provided with a first locking part 317 at the end away from the third mounting part 313, and the first locking part 317 is provided with a first clamping hole 318. The second clamping part 312 is provided with a second locking part 319 at the end away from the third mounting part 313, and the second locking part 319 is provided with a second clamping hole 320. Clamping bolts are provided in the first clamping hole 318 and the second clamping hole 320.

[0027] like Figure 1 and Figure 5 As shown, the triangular fixing clamp 31 is provided with a ball bearing holder 5. The ball bearing holder 5 is provided with a bolt hole 51 and a ball hole 52. More than half of the volume of the ball 4 is installed in the ball hole 52. In order to reduce the rolling resistance of the ball 4, grease can be applied. In addition, both the ball 4 and the ball bearing holder 5 have a certain elasticity and can undergo elastic deformation, which facilitates the installation of the ball 4 into the ball hole 52. The ball bearing holder 5 is fixed to the first clamping part 311 or the second clamping part 312 by clamping bolts.

[0028] Example 2: like Figure 6 and Figure 7 As shown, the difference from Embodiment 1 is that the triangular fixing clip 31 includes a left clip 37 and a right clip 38. The left clip 37 is provided with a first overlapping part 371, a first connecting part 372, a first clamping part 311 and a first locking part 317. The first clamping part 311 is provided with an inwardly protruding first arc-shaped limiting part 373 to restrict the position of the cable 8 inside the triangular fixing clip 31. The right clip 38 is provided with a second overlapping part 381, a second connecting part 382, ​​a second clamping part 312 and a second locking part 319. The second clamping part 312 is provided with an inwardly protruding second arc-shaped limiting part 383 to restrict the position of the cable 8 inside the triangular fixing clip 31. The first overlapping part 371 overlaps with the second overlapping part 381. The first overlapping part 371 is provided with a left mounting hole and the second overlapping part 381 is provided with a right mounting hole. The bolt passes through the left mounting hole and the right mounting hole to install the triangular fixing clip 31 on the inner ring 2. In one embodiment, the left clamp 37 or the right clamp 38 is provided with a spherical ball bearing hole 52, and the ball bearing 4 is installed in the spherical ball bearing hole 52.

[0029] Example 3: like Figure 8 and Figure 9 As shown, the difference from Embodiment 1 is that the inner ring 2 is provided with a ball bearing rod 6, which is installed in the mounting hole of the inner ring 2.

[0030] like Figure 9 and Figure 10 As shown, in one embodiment, the ball screw 6 includes a first nut 61, a second nut 62, a screw 63, and a sleeve 64. One end of the screw 63 is installed on the inner ring 2 and the other end is threadedly connected to the sleeve 64. The sleeve 64 is provided with a ball seat 65 to rotatably install the ball 4. The first nut 61 locks the screw 63 in the inner ring 2, and the second nut 62 locks the screw 63 and the sleeve 64 in a certain relative position.

[0031] like Figure 9 and Figure 10 As shown, in one embodiment, the outer cylinder 1 includes a first half-cylinder 10 and a second half-cylinder 11. The first half-cylinder 10 and the second half-cylinder 11 adopt the same symmetrical design. Both the first half-cylinder 10 and the second half-cylinder 11 are provided with a left wing plate 12 and a right wing plate 13. The left wing plate 12 and the right wing plate 13 are provided with multiple mounting holes.

[0032] like Figure 8 and Figure 10 As shown, in one embodiment, a retaining ring 7 is provided at the lower end of the outer cylinder 1. The retaining ring 7 has a semi-circular cross-section and is fixed to the inner wall of the outer cylinder 1 by screws. During installation and use, the central axis of the outer cylinder 1 is located in the vertical direction, which facilitates the inner ring 2 to move up and down and rotate inside the outer cylinder 1.

[0033] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] It should be understood that if the directional terms such as "upper," "lower," "front," "rear," "left," and "right" are used to describe the embodiments of this application from the angle shown in a certain drawing, they should not be construed as limiting the embodiments of this application. In addition, in the context, it should also be understood that when it is mentioned that a component is connected to another component "upper" or "lower," it can be directly connected to the other component "upper" or "lower," or it can be indirectly connected to the other component "upper" or "lower" through an intermediate component.

[0036] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A cable twist protection device for wind turbine generator sets, characterized in that: The device includes an outer cylinder (1), an inner ring (2), a fixing clamp (3), and a ball bearing (4). The inner ring (2), the fixing clamp (3), and the ball bearing (4) are disposed inside the cylindrical outer cylinder (1). The fixing clamp (3) has multiple parts installed on the inner ring (2). The ball bearing (4) has multiple parts installed in a rotatable manner on the outermost end of the inner ring (2) or the fixing clamp (3) so that the ball bearing (4) abuts against the outer cylinder (1). The inner ring (2) moves linearly up and down along the inner wall of the outer cylinder (1) or rotates relative to the outer cylinder (1) under the limiting action of the ball bearing (4).

2. The wind turbine generator cable twisting protection device according to claim 1, characterized in that: The fixing clip (3) includes a triangular fixing clip (31), which has a first clamping part (311), a second clamping part (312) and a third mounting part (313). The first clamping part (311), the second clamping part (312) and the third mounting part (313) are distributed on the three sides of an equilateral triangle. The third mounting part (313) has a third mounting groove (314) and a third mounting hole (315). The triangular fixing clip (31) is mounted on the inner ring (2) through the third mounting hole (315). The depth of the third mounting groove (314) is greater than the thickness of the bolt head (316) so that the bolt head (316) is completely embedded in the third mounting groove (314).

3. The wind turbine generator cable torsion protection device according to claim 2, characterized in that: The first clamping part (311) is provided with a first locking part (317) at the end away from the third mounting part (313), and the first locking part (317) is provided with a first clamping hole (318). The second clamping part (312) is provided with a second locking part (319) at the end away from the third mounting part (313), and the second locking part (319) is provided with a second clamping hole (320). The first clamping hole (318) and the second clamping hole (320) are provided with clamping bolts.

4. The wind turbine generator cable twisting protection device according to claim 3, characterized in that: The triangular fixing clamp (31) is provided with a ball bearing frame (5), which is fixed to the first clamping part (311) or the second clamping part (312) by clamping bolts.

5. The wind turbine generator cable torsion protection device according to claim 3, characterized in that: The triangular fixing clip (31) includes a left clip (37) and a right clip (38). The left clip (37) is provided with a first overlapping part (371), a first connecting part (372), a first clamping part (311) and a first locking part (317). The first clamping part (311) is provided with an inwardly protruding first arc-shaped limiting part (373). The right clip (38) is provided with a second overlapping part (381), a second connecting part (382), a second clamping part (312) and a second locking part (319). The second clamping part (312) is provided with an inwardly protruding second arc-shaped limiting part (383). The first overlapping part (371) overlaps with the second overlapping part (381). The first overlapping part (371) is provided with a left mounting hole, and the second overlapping part (381) is provided with a right mounting hole. The bolt passes through the left mounting hole and the right mounting hole to install the triangular fixing clip (31) on the inner ring (2).

6. The wind turbine generator cable twisting protection device according to claim 5, characterized in that: The left clamp (37) or the right clamp (38) is provided with a spherical ball hole (52), and the ball (4) is installed in the ball hole (52).

7. The wind turbine generator cable torsion protection device according to claim 2, characterized in that: The inner ring (2) is provided with a ball rod (6), which is installed in the mounting hole of the inner ring (2).

8. The wind turbine generator cable twisting protection device according to claim 7, characterized in that: The ball screw (6) includes a first nut (61), a second nut (62), a screw (63), and a sleeve (64). One end of the screw (63) is installed on the inner ring (2), and the other end is threaded to the sleeve (64). The sleeve (64) is provided with a ball (4) seat to rotatably install the ball (4). The first nut (61) locks the screw (63) in the inner ring (2), and the second nut (62) locks the screw (63) and the sleeve (64) in a certain relative position.

9. The wind turbine generator cable torsion protection device according to any one of claims 1-8, characterized in that: The outer cylinder (1) includes a first half-cylinder (10) and a second half-cylinder (11). The first half-cylinder (10) and the second half-cylinder (11) adopt the same symmetrical design. The first half-cylinder (10) and the second half-cylinder (11) are provided with a left wing plate (12) and a right wing plate (13). The left wing plate (12) and the right wing plate (13) are provided with multiple mounting holes.

10. The wind turbine generator cable torsion protection device according to claim 9, characterized in that: The lower end of the outer cylinder (1) is provided with a retaining ring (7), the retaining ring (7) has a semi-circular cross section and is fixed to the inner wall of the outer cylinder (1) by screws.

Images