Corrugated pipe type contact triggering device

Abstract

The utility model relates to a corrugated pipe type contact triggering device which comprises an outer cylinder. The first corrugated pipe fitting is arranged at the upper part in the outer cylinder and is used for sealing first gas; the second corrugated pipe fitting is arranged at the lower part in the outer cylinder, is oppositely connected with the first corrugated pipe and is used for sealing second gas; the adjusting alarm assembly is arranged on the outer cylinder; one end of the transmission assembly extends into the first corrugated pipe, and the other end extends out of the outer cylinder and is connected with the adjusting alarm assembly; and when the pressure of the second gas is smaller than that of the first gas, the second corrugated pipe fitting is used for driving the transmission assembly connected with the first corrugated pipe fitting to descend to trigger the adjusting alarm assembly. According to the utility model, by utilizing the physical characteristics of the first corrugated pipe fitting and the second corrugated pipe fitting, stability is maintained under the switching-on and switching-off operation or the external vibration environment, and the false alarm problem caused by vibration is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of electric power devices, and particularly relates to a corrugated pipe type contact trigger device. Background Art

[0002] In the power system, SF6 gas or mixed gas is widely used in high-voltage switchgear to improve the insulation performance of the equipment; higher requirements are put forward for the seismic resistance of the density controller used to monitor the SF6 gas state in the switch gas chamber and the stability of the contacts. It is necessary to ensure that the SF6 density controller does not have the quality problem of false alarm when the switch is switched on or off or vibrates.

[0003] The traditional electric contact type SF6 density controller uses a bourdon tube as the pressure measuring element and an electric contact as the contact device. The contact is driven by the rotation of the pointer to send a contact signal. Since the traditional electric contact type SF6 density controller uses a bourdon tube as the pressure measuring element, the accuracy is low, and when the switch is switched on or off, there is strong vibration, and the traditional electric contact type SF6 density controller will have false alarm phenomena, bringing great potential safety hazards to the operation of power equipment.

[0004] The traditional electric contact type SF6 density controller can only be applied to the normally open mode and cannot be used in the normally closed mode. The traditional electric contact SF6 density controller uses an electric contact as the contact device, and due to the limitation of its own structure, the electric contact can only be applied in the state where the contact is normally open. When it is applied to a switch with a normally closed contact, the contact will have an instantaneous break phenomenon when the switch vibrates, which sends a false alarm signal to the background, thus causing misjudgment in the background control.

[0005] Based on the above problems, the utility model proposes a corrugated pipe type contact trigger device. Content of the Utility Model

[0006] The purpose of the utility model is to provide a corrugated pipe type contact trigger device. To achieve the above purpose, the technical scheme adopted by the utility model is as follows:

[0007] A corrugated pipe type contact trigger device includes:

[0008] An outer cylinder;

[0009] A first corrugated pipe member, arranged at the upper part inside the outer cylinder, for sealing a first gas;

[0010] A second corrugated pipe member, arranged at the lower part inside the outer cylinder, connected to the first corrugated pipe relatively, and the second corrugated pipe member is used for sealing a second gas;

[0011] An adjustment and alarm assembly, arranged on the outer cylinder, for sending alarm and locking signals;

[0012] The transmission component has one end extending into the first corrugated pipe and the other end extending out of the outer cylinder and connecting to the adjustment and alarm component.

[0013] When the air pressure of the second gas is less than that of the first gas, the second corrugated pipe component is used to drive the transmission component connected to the first corrugated pipe component to descend, triggering the adjustment and alarm component to send alarm and locking signals.

[0014] Further, the first corrugated pipe component includes a limit plate, a first corrugated pipe, and a first connecting plate;

[0015] The limit plate is arranged at the upper top inside the outer cylinder;

[0016] One end of the first corrugated pipe is connected to one end of the limit plate;

[0017] The first connecting plate is connected to the other end of the first corrugated pipe, and a first groove is arranged at the bottom of the first connecting plate.

[0018] Further, an air inlet pipe is arranged on the limit plate. One end of the air inlet pipe is communicated with the first corrugated pipe, and a plug is arranged at the other end. A connecting channel is arranged at the center of the limit plate. One end of the connecting channel extends into the first corrugated pipe, and the other end extends out of the top plate of the outer cylinder.

[0019] Further, the second corrugated pipe component includes a second connecting plate, a second corrugated pipe, a connecting head, and a limit shaft;

[0020] A first protrusion is arranged on the upper top of the second connecting plate, and the first protrusion is connected with the first groove in a matching manner;

[0021] One end of the second corrugated pipe is connected to the bottom of the second connecting plate;

[0022] The top end of the connecting head is connected to the other end of the second corrugated pipe, and the bottom end of the connecting head is connected to the outer cylinder;

[0023] The limit shaft is arranged on the top end of the connecting head.

[0024] Further, the adjustment and alarm component includes a circuit board, a microswitch, an adjustment plate, an adjustment screw, and a signal wire;

[0025] The circuit board is arranged on the fixing plate at the top end of the outer cylinder through insulating columns;

[0026] The microswitch is arranged on the circuit board;

[0027] The adjustment plate is connected to the transmission component. An adjustment screw is arranged on the adjustment plate, and the adjustment screw is aligned with the center of the switch contact of the microswitch.

[0028] The signal line is connected to the circuit board.

[0029] Further, the transmission assembly includes a movable rod, a third corrugated pipe, and a transmission shaft;

[0030] The bottom end of the movable rod is connected to the center of the bottom of the first connecting plate, and its top end passes through the connecting channel and is movably connected to the connecting channel;

[0031] The bottom end of the transmission shaft is connected to the top end of the movable rod, and its top end passes through the circuit board and the micro switch and is connected to the adjusting plate;

[0032] The third corrugated pipe is sleeved on the movable rod. One end of the third corrugated pipe is connected to the bottom end of the movable rod, and the other end is connected to one end of the connecting channel extending into the first corrugated pipe.

[0033] Further, a second groove is provided at the bottom end of the movable rod, a second protrusion is provided at the center of the bottom of the first connecting plate, and the second protrusion is matched with the second groove; a third groove is provided at the top end of the movable rod, and a third protrusion is provided at the bottom end of the transmission shaft, and the third protrusion is matched with the third groove.

[0034] Further, internal threads are provided inside both the second groove and the third groove, external threads are provided on the outer peripheries of both the second protrusion and the third protrusion, the second groove is in threaded cooperation with the second protrusion, and the third groove is in threaded cooperation with the third protrusion.

[0035] Further, one end of the connecting channel extending out of the top plate of the outer cylinder is fixed at the top plate of the outer cylinder through a lock nut.

[0036] Due to the adoption of the above technical solutions, the present utility model has the following advantages:

[0037] Compared with the existing technology, a bellows-type contact trigger device of the present utility model, through the sealing design of the first corrugated pipe component and the second corrugated pipe component, can more accurately sense and monitor the pressure changes of two different gases, ensuring the accurate monitoring of the density of sulfur hexafluoride gas in the power system. Utilizing the physical properties of the first corrugated pipe component and the second corrugated pipe component, it remains stable during opening and closing operations or in an external vibration environment, reducing false alarm problems caused by vibration. At the same time, the normally open and normally closed of the contact signal can be freely selected, which can meet the wiring of both normally open and normally closed high-voltage switches, solving the problem that traditional density controllers can only be used for contacts that are normally open. Description of the Drawings

[0038] Figure 1It is a schematic structural diagram of the first corrugated pipe fitting, the second corrugated pipe fitting, the adjustment and alarm assembly, and the transmission assembly of a corrugated pipe type contact trigger device of the present utility model.

[0039] Figure 2 It is a schematic overall structural diagram of a corrugated pipe type contact trigger device of the present utility model.

[0040] Figure 3 It is a top view of a corrugated pipe type contact trigger device of the present utility model.

[0041] The reference numerals are as follows: 1 - outer cylinder, 2 - first corrugated pipe fitting, 201 - limit plate, 2011 - intake pipe, 2012 - plug, 2013 - connection channel, 202 - first corrugated pipe, 203 - first connecting plate, 2031 - first groove, 3 - second corrugated pipe fitting, 301 - second connecting plate, 3011 - first protrusion, 302 - second corrugated pipe, 303 - connecting head, 304 - limit shaft, 4 - adjustment and alarm assembly, 401 - circuit board, 402 - micro switch, 403 - adjustment plate, 404 - adjustment screw, 405 - signal wire, 406 - insulating column, 5 - transmission assembly, 501 - movable rod, 5011 - second groove, 5012 - third groove, 502 - third corrugated pipe, 503 - transmission shaft, 5031 - third protrusion, 6 - fixing plate, 7 - wire retaining ring, 8 - sealing ring, 9 - fastening screw, 10 - locking nut, 11 - adjusting nut, 12 - limit nut. Detailed implementation manners

[0042] The following will describe the preferred embodiments of the present utility model in detail with reference to the drawings, so as to more clearly understand the purpose, features and advantages of the present utility model. It should be understood that the embodiments shown in the drawings do not limit the scope of the present utility model, but only illustrate the essential spirit of the technical solution of the present utility model.

[0043] As Figures 1-3 shown. The present utility model provides a corrugated pipe type contact trigger device, including an outer cylinder 1; a first corrugated pipe fitting 2 is arranged in the upper part of the outer cylinder 1 for sealing the first gas; a second corrugated pipe fitting 3 is arranged in the lower part of the outer cylinder 1 and is connected to the first corrugated pipe 2 relatively, and the second corrugated pipe fitting is used for sealing the second gas; an adjustment and alarm assembly 4 is arranged on the outer cylinder 1; one end of a transmission assembly 5 extends into the first corrugated pipe 2, and the other end thereof extends out of the outer cylinder 1 and is connected to the adjustment and alarm assembly 4; when the air pressure of the second gas is less than that of the first gas, the second corrugated pipe fitting 3 is used to drive the transmission assembly 5 connected to the first corrugated pipe fitting 2 to descend to trigger the adjustment and alarm assembly 4.

[0044] As a preference, the first gas can preferably be SF6 gas or a mixed gas;

[0045] As a preference, the second gas may preferably be SF6 gas or a mixed gas.

[0046] Specifically, the first corrugated pipe fitting 2 includes a limiting plate 201, a first corrugated pipe 202 and a first connecting plate 203; the limiting plate 201 is arranged at the upper top inside the outer cylinder 1; one end of the first corrugated pipe 202 is connected to one end of the limiting plate 201; the first connecting plate 203 is connected to the other end of the first corrugated pipe 202, and a first groove 2031 is arranged at the bottom of the first connecting plate 203.

[0047] Specifically, an air inlet pipe 2011 is arranged on the limiting plate 201, one end of the air inlet pipe 2011 is communicated with the first corrugated pipe 202, a plug 2012 is arranged at the other end thereof, a connecting channel 2013 is arranged at the center of the limiting plate 201, one end of the connecting channel 2013 extends into the first corrugated pipe 202, and the other end thereof extends out of the top plate of the outer cylinder 1.

[0048] In this embodiment, the lower end of the first corrugated pipe is welded to the first connecting plate, and the upper end is welded to the limiting plate. The transmission assembly is fixed on the first connecting plate by threads. When the first corrugated pipe moves up and down, the transmission assembly will also move up and down. During this process, the movement of the transmission assembly drives the adjustment and alarm assembly to move up and down. The air inlet pipe is welded on the limiting plate, and the reference gas is filled into the first corrugated pipe through the air inlet pipe, and then the air inlet pipe is completely sealed by the filling and welding of the plug, so as to completely seal the first corrugated pipe fitting and form an independent sealing assembly.

[0049] Specifically, the second corrugated pipe fitting 3 includes a second connecting plate 301, a second corrugated pipe 302, a connecting head 303 and a limiting shaft 304; a first protrusion 3011 is arranged on the upper top of the second connecting plate 301, and the first protrusion 3011 is matched and connected with the first groove 2031; one end of the second corrugated pipe 302 is connected to the bottom of the second connecting plate 301; the top end of the connecting head 303 is connected to the other end of the second corrugated pipe 302, and the bottom end thereof is connected to the outer cylinder 1; the limiting shaft 304 is arranged on the top end of the connecting head 303.

[0050] Furthermore, the first corrugated pipe fitting and the second corrugated pipe fitting are fixed inside the outer cylinder by a wire retaining ring 7, so as to form a set of transmission mechanism.

[0051] In this embodiment, the upper end of the second corrugated pipe is welded to the second connecting plate, and the lower end is welded to the connecting head. The limiting shaft is fixed on the connecting head to form a limit when the second corrugated pipe moves, so as to prevent the second corrugated pipe from forming destructive deformation due to excessive compression.

[0052] Further, at least three sealing rings 8 are provided on the connector 303, and the sealing rings 8 form a seal with the outer cylinder; a fastening screw 9 is welded to the lower end of the connector 303, and the fastening screw 9 matches the hole on the outer cylinder. By inserting a screwdriver deep into the position of the fastening screw, the second corrugated pipe fitting can be tightened and fastened.

[0053] Specifically, the adjustment and alarm assembly 4 includes a circuit board 401, a micro switch 402, an adjustment plate 403, adjustment screws 404 and an alarm; the circuit board 401 is arranged on the top plate of the outer cylinder 1 through an insulating column 406; the micro switch 402 is arranged on the circuit board 401; the adjustment plate 403 is connected to the transmission assembly 5, and adjustment screws 404 are arranged on the adjustment plate 403, and the adjustment screws 404 are aligned with the center of the switch contact of the micro switch 402; a signal line 405 is connected to the circuit board 401, so that alarm and locking signals can be sent to the background through the signal line 405; the micro switch 402 has two wiring terminals, namely normally open and normally closed, so three signal lines are sent out by each micro switch, and the normally open and normally closed signals can be freely selected.

[0054] Further, the adjustment screws 404 are divided into an alarm adjustment screw and a locking adjustment screw. The alarm adjustment screw is aligned with the center of the alarm switch contact of the micro switch, and the locking adjustment screw is aligned with the center of the locking switch contact of the micro switch. When the gas leaks to the alarm pressure, the alarm adjustment screw on the adjustment plate moves downward to press the contact on the micro switch, and the contact touches the internal device of the micro switch, so as to send an alarm signal to the background through the signal line; when the gas in the switch gas chamber continues to leak, the gas pressure in the second corrugated pipe fitting will continue to gradually decrease. When the gas leaks to the locking pressure, the locking adjustment screw on the adjustment plate moves downward to press the contact on the micro switch, and the contact touches the internal device of the micro switch, so as to send a locking signal to the background through the signal line.

[0055] In this embodiment, the fixing plate is fixed to the upper end of the outer cylinder through a locking nut to form the top plate platform of the outer cylinder 1. There are four screw holes on the fixing plate, and the circuit board is fixed thereon through screws. The bottom end of the circuit board is assembled with insulating columns; four micro switches are welded on the circuit board, and a signal line is welded to the other end of the circuit board to form a loop with the micro switch; the adjustment plate is fixed on the transmission shaft and locked through an adjustment nut; four adjustment screws are fixed on the adjustment plate and aligned with the centers of the contacts on the four micro switches at the lower end; there is a slotted head on the adjustment screw, and by rotating the adjustment screw with a flat-blade screwdriver, the position of the trigger signal of the micro switch can be adjusted.

[0056] Specifically, the transmission assembly 5 includes a movable rod 501, a third bellows 502, and a transmission shaft 503. The bottom end of the movable rod 501 is connected to the center of the bottom of the first connecting plate 203. Its top end passes through the connecting channel 2013 and is movably connected to the connecting channel 2013. The bottom end of the transmission shaft 503 is connected to the top end of the movable rod 501. Its top end passes through the circuit board 401 and the microswitch 402 and is connected to the adjusting plate 403. The top of the transmission shaft 503 is limited on the adjusting plate by an adjusting nut 11. The transmission shaft 503 is limited between the circuit board 401 by a limit nut 12. The third bellows 502 is sleeved on the movable rod 501. One end of the third bellows 502 is connected to the bottom end of the movable rod 501, and the other end is connected to one end of the connecting channel 2013 extending into the first bellows 202.

[0057] The first bellows 2 is a reference bellows, the second bellows is a system bellows, and the third bellows is a transmission bellows.

[0058] In this embodiment, the lower end of the first bellows is welded to the first connecting plate, the upper end is welded to the limiting plate, the movable rod is fixed on the first connecting plate by threads, the lower end of the movable rod is welded to the third bellows (transmission bellows), the upper end is fixed to the transmission shaft, the upper end of the third bellows is welded to the inside of the limiting plate. After the upper and lower welding of the third bellows is completed, its inner cavity is independent of the inner cavity of the second bellows. When the second bellows moves up and down, the third bellows will also move up and down accordingly.

[0059] Specifically, a second groove 5011 is provided at the bottom end of the movable rod 501, and a second protrusion 2031 is provided at the center of the bottom of the first connecting plate 203. The second protrusion 2031 matches the second groove 5011. A third groove 5012 is provided at the top end of the movable rod 501, and a third protrusion 5031 is provided at the bottom end of the transmission shaft 503. The third protrusion 5031 matches the third groove 5012.

[0060] Specifically, internal threads are provided inside both the second groove 5011 and the third groove 5012, external threads are provided on the outer circumferences of both the second protrusion 2031 and the third protrusion 5031. The second groove 5011 is in threaded cooperation with the second protrusion 2031, and the third groove 5012 is in threaded cooperation with the third protrusion 5031.

[0061] Specifically, one end of the connecting channel 2013 extending out of the top plate of the outer cylinder 1 is fixed to the top plate of the outer cylinder 1 by a locking nut 6.

[0062] Since the utility model adopts a combined system of a corrugated pipe and a micro switch, the high strength of the corrugated pipe enables the vibration during the opening and closing of the high-voltage switch not to have any impact on it, thus fundamentally solving the problem of false alarms caused by vibration. Therefore, this combination has high seismic resistance. At the same time, the normally open and normally closed of the contact signal can be freely selected, which can meet the wiring of two types of high-voltage switches with normally open and normally closed contacts, and solves the problem that the traditional density controller can only be used for high-voltage switches with normally open contacts; due to the high stability of the corrugated pipe and the high sensitivity of the micro switch, the contact accuracy can reach 0.5 - 0.8 level, which doubles the accuracy compared with the 1.0 level of the traditional density controller.

[0063] As Figures 1-3 shown. The working principle of a corrugated pipe type contact triggering device provided by the utility model is described as follows:

[0064] The device seals SF6 gas or a mixed gas with a rated pressure inside the first corrugated pipe fitting. When the device starts to work, after filling SF6 gas or a mixed gas with a pressure greater than the rated pressure inside the second corrugated pipe fitting, the second corrugated pipe fitting expands at this time, forming an upward movement, and the first corrugated pipe fitting is pushed upward through the up and down movement of the second connecting plate; since the upper end of the first corrugated pipe fitting is fixed by a wire retaining ring, after receiving the force from the second corrugated pipe fitting, the first corrugated pipe fitting is in a compressed state, thereby driving the movable rod to move, and the movable rod pushes the transmission shaft upward; the transmission shaft drives the adjusting plate to move upward, and the four adjusting screws on the adjusting plate also move upward accordingly; at this time, the bottom end of the adjusting screw is in a non-contact state with the contact on the micro switch. When the high-voltage switch is opened and closed or experiences strong vibration, the first corrugated pipe fitting and the second corrugated pipe fitting will not be affected by the vibration due to their own strong force, and the first corrugated pipe fitting and the second corrugated pipe fitting will not cause the adjusting plate to move up and down or vibrate due to vibration; secondly, since the adjusting screw is not in contact with the micro switch and there is a certain gap between the two, no matter how strong the vibration is, it will not cause the adjusting screw to touch the contact of the micro switch, so there will be no false alarm phenomenon.

[0065] When the gas in the switch gas chamber leaks, the gas pressure inside the second corrugated pipe fitting will gradually decrease. When the gas leaks to the alarm pressure, the alarm adjusting screw on the adjusting plate moves downward to press the contact on the micro switch, and the contact touches the internal device of the micro switch, thereby sending an alarm signal through the signal line; when the gas in the switch gas chamber continues to leak, the gas pressure inside the second corrugated pipe fitting will continue to gradually decrease. When the gas leaks to the locking pressure, the locking adjusting screw on the adjusting plate moves downward to press the contact on the micro switch, and the contact touches the internal device of the micro switch, thereby sending a locking signal through the signal line.

Claims

1. A bellows type contact trigger device, characterized in that: include: outer cylinder(1); A first bellows member (2) is arranged at the upper part of the outer tube (1) and is used to seal the first gas; A second bellows member (3) is arranged at the lower part of the outer tube (1) and is connected to the first bellows member (2), and is used to seal a second gas; An adjustment alarm component (4) is arranged on the outer cylinder (1) and is used to send alarm and locking signals; A transmission component (5), one end of which extends into the first corrugated pipe (2), and the other end of which extends out of the outer tube (1) to be connected to the regulating alarm component (4); When the gas pressure of the second gas is lower than the gas pressure of the first gas, the second bellows member (3) is used to drive the transmission component (5) connected to the first bellows member (2) to descend, thereby triggering the regulating alarm component (4) to send an alarm and locking signal.

2. A bellows type contact trigger device according to claim 1, characterized in that: The first bellows member (2) comprises a limiting plate (201), a first bellows (202) and a first connecting plate (203); The limiting plate (201) is arranged at the upper top of the outer cylinder (1); One end of the first corrugated tube (202) is connected to one end of the limiting plate (201); The first connecting plate (203) is connected to the other end of the first corrugated tube (202), and a first groove (2031) is provided at the bottom of the first connecting plate (203).

3. A bellows type contact trigger device according to claim 2, characterized in that: An air inlet pipe (2011) is arranged on the limiting plate (201), one end of the air inlet pipe (2011) is connected to the first corrugated pipe (202), and the other end thereof is arranged with a plug (2012); a connecting channel (2013) is arranged at the center of the limiting plate (201), one end of the connecting channel (2013) extends into the first corrugated pipe (202), and the other end thereof extends out of the top plate of the outer cylinder (1).

4. A bellows type contact trigger device according to claim 3, characterized in that: The second bellows member (3) comprises a second connecting plate (301), a second bellows (302), a connecting head (303) and a limiting shaft (304); A first protrusion (3011) is provided on the top of the second connecting plate (301), and the first protrusion (3011) is matched and connected with the first groove (2031); One end of the second bellows (302) is connected to the bottom of the second connecting plate (301); The top end of the connector (303) is connected to the other end of the second bellows (302), and the bottom end thereof is connected to the outer cylinder (1); The limiting shaft (304) is arranged on the top end of the connecting head (303).

5. A bellows type contact trigger device according to claim 4, characterized in that: The adjustment alarm component (4) comprises a circuit board (401), a micro switch (402), an adjustment plate (403), an adjustment screw (404) and a signal line (405); The circuit board (401) is arranged on a fixing plate (6) at the top end of the outer cylinder (1) via an insulating column (406); The micro switch (402) is arranged on the circuit board (401); An adjustment plate (403) is connected to the transmission assembly (5), an adjustment screw (404) is provided on the adjustment plate (403), and the adjustment screw (404) is aligned with the center of the switch contact of the micro switch (402); The signal line (405) is connected to the circuit board (401).

6. A bellows type contact trigger device according to claim 5, characterized in that: The transmission assembly (5) comprises a movable rod (501), a third bellows (502) and a transmission shaft (503); The bottom end of the movable rod (501) is connected to the bottom center of the first connecting plate (203), and the top end thereof passes through the connecting channel (2013) and is movably connected to the connecting channel (2013); The bottom end of the transmission shaft (503) is connected to the top end of the movable rod (501), and the top end thereof passes through the circuit board (401) and the micro switch (402) to be connected to the adjustment plate (403); The third bellows (502) is sleeved on the movable rod (501), one end of the third bellows (502) is connected to the bottom end of the movable rod (501), and the other end is connected to an end of the connecting channel (2013) extending into the first bellows (202).

7. A bellows type contact trigger device according to claim 6, characterized in that: The bottom end of the movable rod (501) is provided with a second groove (5011), and the bottom center of the first connecting plate (203) is provided with a second protrusion (2032), and the second protrusion (2032) matches the second groove (5011); the top end of the movable rod (501) is provided with a third groove (5012), and the bottom end of the transmission shaft (503) is provided with a third protrusion (5031), and the third protrusion (5031) matches the third groove (5012).

8. The bellows type contact trigger device according to claim 7, characterized in that: The interior of the second groove (5011) and the third groove (5012) are both provided with internal threads, and the outer peripheries of the second protrusion (2032) and the third protrusion (5031) are both provided with external threads. The second groove (5011) and the second protrusion (2032) are threadedly matched, and the third groove (5012) and the third protrusion (5031) are threadedly matched.

9. A bellows type contact trigger device according to claim 8, characterized in that: One end of the connecting channel (2013) extending out of the top plate of the outer cylinder (1) is fixed to the top plate of the outer cylinder (1) via a locking nut (10).

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