A bladder accumulator

Abstract

The application relates to the technical field of accumulators, and particularly discloses a skin bag type accumulator, which comprises a tank body and a skin bag located in the tank body, the inside of the tank body is provided with an upper support and a lower support located on the upper side and the lower side of the skin bag respectively, the lower support can be lifted to compress the skin bag to store energy when oil enters the tank body, and the upper support can be lifted and lowered in the tank body to release or compress the space where the skin bag is located; a sliding rheostat is arranged on the tank body, and a variable resistance sliding block is arranged on the sliding rheostat; the skin bag type accumulator can realize compression of the skin bag by cooperation of the upper support and the lower support during energy storage, can detect the lifting height of the lower support, can realize real-time monitoring of the change of the gas pressure in the skin bag by the sliding rheostat outside the tank body, can facilitate maintenance of the detection equipment, can timely alarm and warn when the pressure of the skin bag is abnormal, and can effectively avoid damage of the equipment caused by untimely discovery of the abnormal pressure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of accumulators, in particular to a skin bag type accumulator. BACKGROUND

[0002] The skin bag type accumulator is a commonly used energy storage element in hydraulic systems, which separates gas and hydraulic oil by a skin bag, stores and releases energy by using the compressibility of gas, and plays an important role in stabilizing system pressure, compensating leakage, and absorbing pressure pulsation.

[0003] The existing skin bag type accumulator has many deficiencies in pressure monitoring and emergency treatment. Most accumulators rely on manual periodic detection of skin bag pressure and cannot real-time master the internal pressure change of the accumulator. When the skin bag has sudden pressure abnormalities, it is difficult to find out in time, which may cause equipment failure and even safety accidents, and may also cause product quality decline or even scrap. Moreover, after finding the abnormal pressure of the skin bag, there is a lack of corresponding emergency treatment function, and the abnormality of the skin bag cannot be adjusted in time, and immediate shutdown for maintenance is often required to avoid greater losses, but it will affect or even interrupt the processing of products being produced, resulting in product defects and scrap, and waste of materials. SUMMARY

[0004] The present application provides a skin bag type accumulator, which aims to solve the problem that when the skin bag has sudden pressure abnormalities, it is difficult to find out in time, and after finding the abnormal pressure of the skin bag, the abnormality of the skin bag cannot be adjusted in time.

[0005] The skin bag type accumulator of the present application comprises a tank body and a skin bag located inside the tank body, the inside of the tank body is provided with an upper support and a lower support located on the upper and lower sides of the skin bag respectively, and the lower support can be lifted when oil enters the tank body to compress and store energy for the skin bag.

[0006] The tank body is provided with a lifting shaft, and the lifting shaft can slide up and down in the tank body to drive the upper support to lift in the tank body, so that the upper support is close to or away from the lower support. A sliding rheostat is arranged on the tank body, a rheostat sliding block is slidably arranged on the sliding rheostat, and the rheostat sliding block can slide relative to the sliding rheostat with the lifting of the lower support. The sliding rheostat can slide relative to the rheostat sliding block with the lifting of the upper support.

[0007] Preferably, the top of the tank body is provided with an upper mounting seat, and the upper mounting seat is detachably connected with the tank body by bolts. The inside of the upper mounting seat is provided with an air pipe, and the air pipe is provided with an inflation valve.

[0008] Preferably, the air pipe is composed of an upper pipe body and a lower pipe body, the upper pipe body is fixedly installed inside the upper mounting seat, the inflation valve is fixedly installed inside the air pipe, the lower pipe body is slidably assembled inside the upper pipe body in single degree of freedom, and the bottom end of the lower pipe body extends into the inside of the tank body and is fixedly connected and communicated with the skin bag.

[0009] Preferably, the upper support is composed of an outer ring and an inner disc, the outer ring is arranged at the top of the skin bag, the inner disc is arranged inside the outer ring, and the inner disc is coaxially fixed outside the bottom end of the lower pipe body.

[0010] Preferably, the top of the outer ring is provided with a stepped groove, the stepped groove is provided with an L-shaped limiting groove inside, a clamping plate is fixedly installed on the inner disc and located in the limiting groove, and the clamping plate can be turned out of the limiting groove with the rotation of the inner disc.

[0011] Preferably, the lower support is composed of a bottom plate and a backing plate, the bottom plate is arranged below the skin bag, the bottom plate can slide in single degree of freedom in the tank body, and a sealing gasket is arranged between the bottom plate and the inner wall of the tank body.

[0012] Preferably, a pedestal is slidably assembled on the tank body, the bottom end of the pedestal extends into the inside of the tank body, a connecting rod is fixedly installed at the top of the outer ring, the top end of the connecting rod is fixedly connected with the pedestal, and a sliding rheostat is fixedly installed on the pedestal.

[0013] Preferably, a sliding rod is vertically fixed on the bottom plate, the side wall of the sliding rod is closely arranged against the inner wall of the tank body, the top end of the sliding rod extends out of the top of the tank body and is fixedly connected with a variable resistance sliding block, a missing groove is arranged on the outer ring and matched with the sliding rod, and the sliding rod is slidably arranged in the missing groove.

[0014] Preferably, an adjusting rod is vertically fixed on the tank body, a lifting shaft is slidably assembled in the adjusting rod, the bottom end of the lifting shaft extends into the tank body and is fixedly connected with the outer ring, and a driving box for driving the lifting shaft to lift is arranged on one side of the adjusting rod.

[0015] Beneficial effects:

[0016] The application can detect the lifting height of the lower support, monitor the change of the gas pressure in the skin bag in real time outside the tank body through the sliding rheostat, timely alarm when the pressure of the skin bag is abnormal, effectively avoid the damage of the equipment caused by the abnormal pressure not being found in time, and automatically make emergency treatment for the abnormal skin bag through the adjusting assembly, adjust the pressure state of the skin bag, so that the skin bag can maintain the normal operation of the equipment in normal state, without shutdown emergency, and the pressure correction can be completed in the production process, avoiding the loss of semi-finished product scrapping, production line interruption and the like, especially suitable for continuous production scenes such as injection molding and hydraulic processing, ensuring high-quality production of products, so that the shutdown maintenance of the energy accumulator can be carried out after the production is completed, avoiding affecting the normal production and processing and causing material waste. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a perspective view of the application.

[0018] Figure 2 is an enlarged structure schematic view of A in the application. Figure 1

[0019] Figure 3 is a front view of the application.

[0020] Figure 4 is a sectional view of the application.

[0021] Figure 5 is a perspective view of the upper support of the application.

[0022] Figure 6 is a split state schematic view of the outer ring and the inner ring of the application.

[0023] REFERENCE SIGNS:

[0024] 10, tank; 11, upper mounting seat; 12, air pipe; 121, upper pipe body; 122, lower pipe body; 123, shield; 13, inflation valve; 14, lower mounting seat; 15, oil pipe; 16, support block; 17, mushroom valve; 20, skin bag; 30, upper support; 31, outer ring; 311, stepped groove; 312, limiting groove; 313, missing groove; 314, connecting rod; 32, inner disc; 321, clamping plate; 40, lower support; 41, bottom plate; 411, sealing gasket; 412, sliding rod; 42, pad plate; 50, detection mechanism; 51, pedestal; 52, sliding rheostat; 53, rheostat sliding block; 60, adjusting assembly; 61, adjusting rod; 62, lifting shaft; 63, drive box. DETAILED DESCRIPTION

[0025] ​Embodiments of the present application are described below in detail, examples of which are shown in the accompanying drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0026] As shown in Figures 1 to 6 , the bladder type energy accumulator of the present application comprises a tank body 10, a bladder 20, an upper support 30, a lower support 40, a detection mechanism 50 and an adjusting assembly 60, the bladder 20 is arranged inside the tank body 10, the upper support 30 and the lower support 40 are respectively located on the upper and lower sides of the bladder 20, the lower support 40 can be lifted inside when the oil enters the inside of the tank body 10, and cooperates with the upper support 30 to extrude the bladder 20, so that the gas in the bladder 20 is compressed and stored, the detection mechanism 50 is arranged between the tank body 10 and the lower support 40, and can detect the compression state of the bladder 20 in the lifting of the lower support 40, the adjusting assembly 60 is arranged on one side of the upper support 30, and can adjust the height of the upper support 30 when the detection mechanism 50 detects that the bladder 20 is compressed abnormally, so as to adjust the compression state of the bladder 20.

[0027] Referring to Figure 1 , Figure 3 and Figure 4 , the top of the tank body 10 is provided with an upper mounting seat 11, and the upper mounting seat 11 is detachably connected with the tank body 10 by bolts, the inside of the upper mounting seat 11 is provided with an air pipe 12 to communicate the inside and outside of the tank body 10, and the air pipe 12 is provided with an inflation valve 13 to close the air pipe 12.

[0028] The air pipe 12 is composed of an upper pipe body 121 and a lower pipe body 122, the upper pipe body 121 is fixedly installed in the inside of the upper mounting seat 11, the inflation valve 13 is fixedly installed in the inside of the air pipe 12, the lower pipe body 122 is slidably assembled in the inside of the upper pipe body 121 in single degree of freedom, the bottom end of the lower pipe body 122 extends to the inside of the tank body 10 and is fixedly connected with the bladder 20 to inflate or deflate the bladder 20, a sealing ring is arranged between the lower pipe body 122 and the upper pipe body 121 to seal the space between the upper pipe body 121 and the lower pipe body 122 and prevent gas leakage, and a protective cover 123 is arranged at the top end of the upper pipe body 121 to protect the pipe opening of the air pipe 12.

[0029] The bottom of the tank body 10 is provided with a lower mounting seat 14, an oil pipe 15 is fixedly installed in the inside of the lower mounting seat 14 to fill or discharge oil into or out of the tank body 10, a support block 16 is fixedly installed in the inside of the oil pipe 15, and a fungus valve 17 is arranged on the support block 16 and located at the upper end of the oil pipe 15.

[0030] Referring to Figure 4 , Figure 5 and Figure 6The upper support 30 is composed of an outer ring 31 and an inner disc 32. The outer ring 31 is arranged at the top of the bladder 20, and the inner disc 32 is arranged inside the outer ring 31 and fixed coaxially at the outer side of the bottom end of the lower tube body 122. The top of the outer ring 31 is provided with a stepped groove 311, and the inside of the stepped groove 311 is provided with an L-shaped limiting groove 312. A clamping plate 321 is fixedly installed on the inner disc 32 and located in the limiting groove 312. The clamping plate 321 can be turned out of the limiting groove 312 with the rotation of the inner disc 32, thereby releasing the limiting between the outer ring 31 and the inner disc 32, so that the inner disc 32 can be separated from the outer ring 31, facilitating the disassembly and replacement of the bladder 20.

[0031] With reference to Figure 4 The lower support 40 is composed of a bottom plate 41 and a pad plate 42. The bottom plate 41 is arranged below the bladder 20 and can slide in a single degree of freedom in the tank body 10. A sealing pad 411 is arranged between the bottom plate 41 and the inner wall of the tank body 10, so that the bottom plate 41 and the tank body 10 are kept in a sealed state. The pad plate 42 is fixedly installed on the top of the bottom plate 41 and is attached to the bottom of the bladder 20, for supporting and pushing the bottom of the bladder 20.

[0032] With reference to Figure 2 , Figure 3 and Figure 4 The detection mechanism 50 includes a pedestal 51, a sliding rheostat 52 and a rheostat sliding block 53. The pedestal 51 is slidably arranged on the tank body 10 and extends into the tank body 10 at the bottom end, so as to be raised and lowered with the outer ring 31. The sliding rheostat 52 is fixedly installed on the pedestal 51. The rheostat sliding block 53 is arranged on the sliding rheostat 52 and can slide in the sliding rheostat 52 with the raising and lowering of the bottom plate 41, so as to facilitate the detection of the gas pressure in the bladder 20.

[0033] The bottom plate 41 is vertically fixed with a slide rod 412, and the side wall of the slide rod 412 is closely arranged against the inner wall of the tank body 10. The top end of the slide rod 412 is fixed with the rheostat sliding block 53, so that the bottom plate 41 can drive the rheostat sliding block 53 to slide on the sliding rheostat 52 when it is raised and lowered, and the gas pressure in the bladder 20 is detected by the sliding rheostat 52. The outer ring 31 is provided with a missing groove 313 matched with the slide rod 412, and the slide rod 412 is slidably arranged in the missing groove 313. The top end of the connecting rod 314 is fixed with the pedestal 51, so that the outer ring 31 and the slide rod 412 can slide relative to each other, and the pedestal 51 is raised and lowered by the connecting rod 314 when the outer ring 31 is raised and lowered, so that the sliding rheostat 52 slides relative to the rheostat sliding block 53, and the detection data display of the sliding rheostat 52 is adjusted accordingly when the pressure of the bladder 20 is adjusted, so as to realize the detection of the gas pressure in the bladder 20.

[0034] With reference to Figure 4 , the adjusting assembly 60 comprises an adjusting rod 61 vertically fixed on the tank body 10, a lifting shaft 62 slidingly assembled in the adjusting rod 61 and having a bottom end extending into the tank body 10 and fixed with the outer ring 31, and a driving box 63 arranged at one side of the adjusting rod 61 and capable of driving the lifting shaft 62 to slide and lift in the adjusting rod 61, thereby driving the outer ring 31 to lift in the tank body 10, adjusting the space between the upper support 30 and the lower support 40, releasing or further compressing the space where the bladder 20 is located, and adjusting the gas pressure in the bladder 20. In the present scheme, the driving box 63 is specifically an electric push rod.

[0035] One side of the sliding rheostat 52 is provided with a controller and an alarm (not shown in the figure), and the alarm and the driving box 63 are both signal connected with the controller. The controller is built-in with a microprocessor and a preset resistance threshold program, can receive the resistance value signal transmitted by the sliding rheostat 52, compare and analyze with the preset resistance threshold value, when the resistance value is higher or lower than the preset threshold interval, transmit a signal to the alarm to issue an alarm warning to the staff, and transmit a signal to the driving box 63 to adjust the lifting shaft 62 to lift the upper support 30 accordingly, so that the driving box 63, the lifting shaft 62 and the upper support 30 are the core components, and form a closed loop control with the detection mechanism 50: after the controller receives the resistance abnormal signal, the lifting shaft 62 is automatically driven to lift the upper support 30, the upper support 30 is lifted to release the pressure when the pressure is too high, the upper support 30 is lowered to compress the space of the bladder 20 to increase the pressure when the pressure is too low, until the resistance value returns to the normal threshold interval.

[0036] In the present scheme, the gas volume in the bladder 20 is determined by the initial volume, the compression amount of the lower support 40 and the adjusting amount of the upper support 30, therefore, the gas volume expression in the scheme satisfies the following formula:

[0037]

[0038] Among them, represents the real-time volume of the gas, the unit is ; represents the initial volume of the gas, the unit is ; represents the equivalent cross-sectional area of the bladder 20 when it is extruded, the unit is ; represents the lifting distance of the variable resistance slider 53 relative to the initial position following the lower support 40, the unit is ; y represents the lifting distance of the sliding rheostat 52 relative to the initial position following the upper support 30, the unit is .

[0039] The real-time volume of the gas Substituting the Boyles law: The relative displacement between the variable resistor slider 53 and the slide rheostat 52 and the pressure of the gas inside the skin bag 20 satisfy the following expression:

[0040]

[0041] Wherein, represents the sliding distance of the variable resistor slider 53 relative to the slide rheostat 52, and the unit is ; represents the initial volume of the gas, and the unit is ; represents the real-time pressure of the gas inside the skin bag 20, and the unit is ; represents the initial pressure of the gas, and the unit is .

[0042] Therefore, the higher the lower support 40 is lifted, the greater the real-time pressure of the gas inside the skin bag 20 The sliding distance of the variable resistor slider 53 relative to the slide rheostat 52 The greater the resistance change will also be greater.

[0043] At the same time, in the variable resistor slider 53, the resistance value changes linearly with the sliding distance of the variable resistor slider 53 relative to the slide rheostat 52 Satisfy the formula:

[0044]

[0045] Wherein, represents the real-time resistance value of the slide rheostat 52, and the unit is ; represents the initial resistance value when ; represents the resistance change corresponding to a unit of relative displacement, and the unit is .

[0046] Therefore, in this scheme, the real-time pressure of the gas inside the skin bag 20 and the real-time resistance on the slide rheostat 52 satisfy the following formula:

[0047]

[0048] The change of the resistance on the slide rheostat 52 can be used to monitor the pressure of the gas inside the skin bag 20 in real time.

[0049] Working principle: the inert gas is filled into the bladder 20 in the tank body 10 from the air pipe 12, and then the bacteria valve 17 is opened. The oil enters from the oil pipe 15 below the tank body 10, and under the action of oil pressure, the lower support 40 is lifted to extrude the bladder 20 together with the upper support 30, so that the inert gas in the bladder 20 is gradually compressed and stored.

[0050] When the lower support 40 is lifted, the variable resistor slider 53 on the sliding variable resistor 52 is pushed to slide by the sliding rod 412 on the bottom plate 41, changing the resistance value of the sliding variable resistor 52, and then the sliding variable resistor 52 detects the pressure on the bladder 20. When the oil pressure makes the lower support 40 lift higher, the pressure on the bladder 20 will be greater, and the resistance value of the sliding variable resistor 52 will change more. When the oil pressure makes the lower support 40 lift lower, the pressure on the bladder 20 will be relatively smaller, and the resistance value of the sliding variable resistor 52 will change less. When the oil stops entering the tank body 10, if the resistance value of the sliding variable resistor 52 received by the controller meets the preset threshold interval, it means that the gas pressure in the bladder 20 is normal, and the equipment is operating normally.

[0051] When the oil stops entering the tank body 10, if the resistance value of the sliding variable resistor 52 received by the controller is greater than the preset threshold interval, it means that the gas pressure in the bladder 20 is too large, and the inert gas is excessively compressed and stored. The equipment is abnormal, the controller transmits a signal to make the alarm issue an alarm to alert the staff, and at the same time transmits a signal to make the drive box 63 operate to drive the lifting shaft 62 to lift the upper support 30, gradually increasing the distance between the upper support 30 and the lower support 40, and then increasing the space range of the bladder 20, so that the gas pressure in the bladder 20 can be gradually released, reducing the gas pressure. At the same time, the sliding variable resistor 52 is lifted relative to the variable resistor slider 53 as the upper support 30 is lifted, so that the sliding variable resistor 52 reduces the resistance value at the same time as the bladder 20 releases the pressure, until the resistance value of the sliding variable resistor 52 received by the controller returns to the normal threshold interval, and then the drive box 63 stops operating again.

[0052] When the oil stops entering the tank 10, and the resistance value of the sliding rheostat 52 received by the controller is less than the preset threshold interval, it indicates that the gas pressure in the bladder 20 is small, the inert gas compression energy storage is insufficient, and the device is abnormal, the controller transmits a signal to make the alarm issue an alarm to warn the staff, and at the same time transmits a signal to drive the lifting shaft 62 of the drive box 63 to make the upper support 30 descend, gradually reduce the distance between the upper support 30 and the lower support 40, and then reduce the space range of the bladder 20, so that the gas in the bladder 20 is further compressed, the gas pressure is increased, and at the same time, the sliding rheostat 52 is lowered relative to the rheostat slider 53 as the upper support 30 is lowered, so that the sliding rheostat 52 is further compressed, and at the same time, the resistance value of the sliding rheostat 52 is increased synchronously, until the resistance value of the sliding rheostat 52 received by the controller returns to the normal threshold interval, and the drive box 63 stops working again.

[0053] In the present application, the compression of the bladder 20 during energy storage is completed by the cooperation of the upper support 30 and the lower support 40, the change of the gas pressure in the bladder 20 can be monitored in real time by the sliding rheostat 52 outside the tank 10 through the detection of the lifting height of the lower support 40, the alarm can be given in time when the pressure of the bladder 20 is abnormal, the damage of the device caused by the failure to find the abnormal pressure in time can be avoided, and the emergency treatment of the abnormal bladder 20 can be automatically made by the adjusting assembly 60, the pressure state of the bladder 20 is adjusted, the bladder 20 can maintain the normal operation of the device in a normal state, the pressure correction can be completed in the production process without shutdown for emergency, the loss such as scrap of semi-finished products and interruption of production line can be avoided, especially suitable for continuous production scenes such as injection molding and hydraulic processing, the high-quality production of products is ensured, the shutdown and maintenance of the energy accumulator can be carried out after the production is completed, the normal production and processing are not affected, and the waste of materials is avoided; the tank 10 with high pressure does not need to be contacted by the staff throughout the process, the remote automatic adjustment is realized through the electric control system, the safety risk of high-pressure operation is reduced, and the core detection components such as the sliding rheostat 52 and the rheostat slider 53 are arranged outside the tank 10, so that the calibration and replacement can be completed without disassembling the energy accumulator, and the cumbersome problem of "shell maintenance" is solved.

[0054] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A bladder accumulator comprising a tank body (10) and a bladder (20) located inside thereof, characterized in that, The inside of the tank body (10) is provided with an upper support (30) and a lower support (40) located on the upper and lower sides of the bladder (20) respectively, and the lower support (40) can be lifted when the oil enters the tank body (10) to compress the bladder (20) to store energy; The inside of the tank body (10) is provided with a lifting shaft (62), and the lifting shaft (62) can slide up and down in the tank body (10) to drive the upper support (30) to lift in the tank body (10), so that it is close to or away from the lower support (40), and the tank body (10) is provided with a sliding resistor (52), and the sliding resistor (52) is provided with a variable resistance slider (53) slidingly, and the variable resistance slider (53) can slide relative to the sliding resistor (52) with the lifting of the lower support (40), and the sliding resistor (52) can slide relative to the variable resistance slider (53) with the lifting of the upper support (30); The lower support (40) is composed of a bottom plate (41) and a pad plate (42), the bottom plate (41) is arranged below the bladder (20), and the bottom plate (41) can slide up and down in the tank body (10) with one degree of freedom, and a sealing pad (411) is arranged between the bottom plate (41) and the inner wall of the tank body (10); The tank body (10) is provided with a pedestal (51) slidingly, and the bottom end of the pedestal (51) extends into the inside of the tank body (10), the top of the outer ring (31) is fixedly installed with a connecting rod (314), and the top end of the connecting rod (314) is fixed with the pedestal (51), and the sliding resistor (52) is fixedly installed on the pedestal (51); The bottom plate (41) is vertically fixed with a sliding rod (412), and the side wall of the sliding rod (412) is closely arranged on the inner wall of the tank body (10), the top end of the sliding rod (412) extends out of the top of the tank body (10) and is fixed with the variable resistance slider (53), and the outer ring (31) is provided with a missing slot (313) matched with the sliding rod (412), and the sliding rod (412) is slidingly arranged in the missing slot (313); The tank body (10) is vertically fixed with an adjusting rod (61), and the lifting shaft (62) is slidingly arranged in the adjusting rod (61), and the bottom end of the lifting shaft (62) extends into the tank body (10) and is fixed with the outer ring (31), and one side of the adjusting rod (61) is provided with a driving box (63) for driving the lifting shaft (62) to lift.

2. The bladder accumulator of claim 1, wherein, The top of the tank body (10) is provided with an upper mounting seat (11), and the upper mounting seat (11) and the tank body (10) are detachably connected by bolts, and the inside of the upper mounting seat (11) is provided with an air pipe (12), and the inside of the air pipe (12) is provided with an inflation valve (13).

3. The bladder accumulator of claim 2, wherein, The air pipe (12) is composed of an upper pipe body (121) and a lower pipe body (122), the upper pipe body (121) is fixedly installed in the inside of the upper mounting seat (11), the inflation valve (13) is fixedly installed in the inside of the air pipe (12), the lower pipe body (122) is slidingly arranged in the inside of the upper pipe body (121) with one degree of freedom, and the bottom end of the lower pipe body (122) extends into the inside of the tank body (10) and is fixedly connected with the bladder (20).

4. The bladder accumulator of claim 3, wherein, The upper support (30) is composed of an outer ring (31) and an inner disc (32), the outer ring (31) is arranged at the top of the bladder (20), the inner disc (32) is arranged inside the outer ring (31), and the inner disc (32) is coaxially fixed outside the bottom end of the lower tube body (122).

5. The bladder accumulator of claim 4, wherein, The top of the outer ring (31) is provided with a stepped groove (311), the inside of the stepped groove (311) is provided with an L-shaped limiting groove (312), a clamping plate (321) is fixedly installed on the inner disc (32) and located in the limiting groove (312), and the clamping plate (321) can be turned out of the limiting groove (312) along with the rotation of the inner disc (32).

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