Wide-range vortex shedding flowmeter

Abstract

The utility model provides a wide-range vortex shedding flowmeter, which belongs to the technical field of pipeline fluid flow detection and comprises a measuring pipe, a supporting sleeve, a threading pipe and a converter. A vortex street generating body is arranged in the measuring tube; a fixed seat is arranged on the outer wall of the measuring tube; the lower end of the supporting sleeve is in threaded connection with the fixing seat; the threading pipe is arranged in the supporting sleeve; the lower end of the threading pipe is connected with a detection probe, and the detection probe extends into the measuring pipe and is located at the downstream of the vortex street generating body; the converter is detachably connected with the upper end of the supporting sleeve through an inserting structure and is electrically connected with the upper end of the threading pipe in an inserting mode. When the detection probe needs to be maintained and replaced, the detection probe can be taken out of the measuring tube only by screwing off the supporting sleeve from the fixed seat or disassembling the insertion structure and taking the detection probe out of the supporting sleeve, the disassembly and assembly mode of the detection probe is simple, tools are not needed, and the maintenance cost is reduced. And rapid maintenance or replacement of the detection probe can be realized.

Description

TECHNICAL FIELD

[0001] The utility model belongs to pipeline fluid flow detection technical field, more specifically, relate to a wide range vortex flowmeter. BACKGROUND

[0002] Vortex flowmeter is according to karman (Karman) vortex principle research and production, mainly for the flow measurement of industrial pipeline medium fluid, such as gas, liquid, steam and a variety of media. Its characteristics are small pressure loss, wide range, high precision, when measuring the volume flow, almost not affected by fluid density, pressure, temperature, viscosity and other parameters.

[0003] Wide range vortex flowmeter generally includes measuring pipe, vortex generator and vortex flow sensor;The detection part of vortex flow sensor and vortex generator are located inside the measuring pipe. Because of the failure of vortex flow sensor, in order to facilitate maintenance and replacement of sensor, detachable connection is adopted between sensor and measuring pipe. In the prior art, the dismounting operation of sensor and measuring pipe is complex, and the sensor cannot be quickly dismounted. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a wide range vortex flowmeter, which aims to solve the technical problem of complex dismounting of vortex flow sensor in the prior art.

[0005] To achieve the above object, the utility model adopts the technical scheme of providing a wide range vortex flowmeter, which comprises:

[0006] Measuring pipe, used for connecting with the measured pipeline;The inside of the measuring pipe is provided with a vortex generator;The outer wall of the measuring pipe is provided with a fixing seat;

[0007] Support sleeve, the lower end is screw connected with the fixing seat;

[0008] Wire pipe, arranged inside the support sleeve;The lower end of the wire pipe is connected with a detection probe, the detection probe extends into the measuring pipe and is located downstream of the vortex generator;And

[0009] Converter, detachably connected with the upper end of the support sleeve through a plug-in structure, and electrically plugged with the upper end of the wire pipe.

[0010] In a possible implementation manner, the fixing seat has an installation cavity with an opening facing upward, and the lower end of the support sleeve is embedded in the installation cavity;The outer wall of the support sleeve is provided with an abutting ring table;The abutting ring table abuts against the top surface of the fixing seat.

[0011] In some embodiments, the inner wall of the support sleeve is provided with a plurality of limiting ring tables distributed along the axial direction; and the threading pipe is tightly sleeved with a plurality of limiting sleeves, which are embedded in the limiting ring tables one by one.

[0012] In some embodiments, the limiting sleeve is a T-shaped rotary body structure, and the transverse part of the limiting sleeve abuts against the top surface of the limiting ring table, and the vertical part of the limiting sleeve abuts against the inner wall of the limiting ring table.

[0013] In some embodiments, the pipe wall of the measuring pipe is provided with a through hole extending in the radial direction, and the lower end of the threading pipe is located in the through hole; and the bottom surface of the lower limiting sleeve tightly abuts against the outer wall of the measuring pipe.

[0014] In a possible implementation, the outer wall of the support sleeve is provided with heat dissipation fins.

[0015] In a possible implementation, the lower end of the threading pipe is provided with a slot, and the detection probe is partially embedded in the slot.

[0016] In a possible implementation, the upper end of the threading pipe is provided with a socket, and the inside of the converter is provided with a plug, which is electrically plugged with the socket.

[0017] In a possible implementation, the lower end of the converter is provided with a first connecting table protruding outward in the radial direction, the upper end of the support sleeve is provided with a second connecting table protruding outward in the radial direction, the first connecting table and the second connecting table abut against each other, and the plug-in structure is arranged between the first connecting table and the second connecting table in the axial and radial directions.

[0018] In some embodiments, the first connecting table is provided with a first insertion hole penetrating in the axial direction, the second connecting table is provided with a blind hole corresponding to the first insertion hole, the second connecting table is further provided with a second insertion hole penetrating in the radial direction, and the second connecting table is further provided with a guide groove communicating with the second insertion hole.

[0019] The plug-in structure includes a first insertion block and a second insertion block, the side wall of the first insertion block is provided with a third insertion hole, and the second insertion block is provided with a sliding block.

[0020] The first insertion block is inserted into the first insertion hole and the blind hole, the second insertion block is inserted into the second insertion hole and the third insertion hole, and the sliding block is located in the guide groove.

[0021] The wide-range vortex flowmeter has the advantages that, compared with the prior art, the wide-range vortex flowmeter, a threading pipe is used for connecting a detection probe and a converter, a supporting sleeve is used for fixing the threading pipe and supporting the converter; when the detection probe needs to be maintained and replaced, the supporting sleeve is rotated off the fixing seat, or the plug-in structure is disassembled and the detection probe is taken out from the supporting sleeve, so that the detection probe can be taken out from the measuring pipe, the detection probe is simple in disassembly and assembly, tools are not needed, and the detection probe can be quickly maintained or replaced. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0023] Figure 1 The structural schematic diagram of the wide-range vortex flowmeter provided by the present application is shown in the figure.

[0024] Figure 2 The structural schematic diagram of the wide-range vortex flowmeter provided by the present application is shown in the figure. Figure 1 The structural schematic diagram of the wide-range vortex flowmeter provided by the present application is shown in the figure.

[0025] Figure 3 The structural schematic diagram of the wide-range vortex flowmeter provided by the present application is shown in the figure. Figure 1 The structural schematic diagram of the wide-range vortex flowmeter provided by the present application is shown in the figure.

[0026] In the figure:

[0027] 1, measuring pipe; 11, fixing seat; 12, through hole;

[0028] 2, supporting sleeve; 21, abutting ring table; 22, limiting ring table; 23, heat dissipation fin; 24, second connecting table; 241, blind hole; 242, second jack; 243, guide groove;

[0029] 3, threading pipe; 31, limiting sleeve; 32, socket;

[0030] 4, detection probe;

[0031] 5, vortex generator;

[0032] 6, converter; 61, plug; 62, first connecting table; 621, first jack;

[0033] 7, plug-in structure; 71, first insertion block; 711, third jack; 72, second insertion block; 721, sliding block. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical schemes and beneficial effects of the utility model clearer, the utility model will be explained in further detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the utility model and not to limit the utility model.

[0035] Please refer to Figure 1 and Figure 2 , the wide range vortex flowmeter provided by the utility model will be described. The wide range vortex flowmeter comprises a measuring pipe 1, a supporting sleeve 2, a threading pipe 3 and a converter 6. The measuring pipe 1 is used to be connected with a measured pipeline; the inside of the measuring pipe 1 is provided with a vortex generator 5; the outer wall of the measuring pipe 1 is provided with a fixing seat 11; the lower end of the supporting sleeve 2 is threadedly connected with the fixing seat 11; the threading pipe 3 is arranged inside the supporting sleeve 2; the lower end of the threading pipe 3 is connected with a detection probe 4, the detection probe 4 extends into the measuring pipe 1 and is located downstream of the vortex generator 5; the converter 6 is detachably connected with the upper end of the supporting sleeve 2 through a plug-in structure 7 and is electrically plugged with the upper end of the threading pipe 3.

[0036] The two ends of the measuring pipe 1 are respectively connected with flanges and are connected with the measured pipeline through the flanges; the fixing seat 11 is arranged on the outer peripheral wall of the measuring pipe 1 and is used to be threadedly connected with the supporting sleeve 2; specifically, the supporting sleeve 2 can be embedded in the inside of the fixing seat 11 or can be sleeved on the outside of the fixing seat 11. It should be noted that no matter which fixing form is used, the supporting sleeve 2 should have a cavity so that the threading pipe 3 can pass through.

[0037] The threading pipe 3 is arranged in the supporting sleeve 2 and can be radially limited to avoid swinging. The upper end of the threading pipe 3 is electrically plugged with the converter 6 and is axially limited through the converter 6.

[0038] The vortex generator 5 and the detection probe 4 are both located inside the measuring pipe 1 and the detection probe 4 is located downstream of the vortex generator 5; the detection probe 4 is fixed through the threading pipe 3 and is electrically connected with the detection circuit in the threading pipe 3; the detection circuit of the threading pipe 3 is also electrically connected with the converter 6.

[0039] When measuring the fluid flow, when the fluid medium flows in the measuring pipe 1, after flowing through the vortex generator 5, alternating vortices are generated on both sides of the vortex generator 5, then the frequency of vortex generation is measured through the detection probe 4, the detection probe 4 transmits the detection signal to the converter 6 through the threading pipe 3, the converter 6 calculates and processes the detection signal, obtains the flow data of the medium and displays the flow data through the display screen connected with the converter 6.

[0040] Because the detection probe 4 has a malfunction issue, when maintenance or replacement of the detection probe 4 is required, the support sleeve 2 can be unscrewed from the fixing base 11, and the support sleeve 2, along with the detection probe 4, can be removed from the measuring tube 1; or the plug-in structure 7 can be removed, the converter 6 can be unplugged, and the wiring tube 3 can be taken out from the support sleeve 2, with the wiring tube 3 carrying the detection probe 4 away from the measuring tube 1. Preferably, the detection probe 4 is disassembled using the first method described above.

[0041] In addition, if converter 6 is faulty, the plug structure 7 can be removed, and then converter 6 can be unplugged to repair or replace converter 6.

[0042] The wide-range vortex flowmeter provided by this utility model has a conduit 3 for connecting the detection probe 4 and the converter 6, and a support sleeve 2 for fixing the conduit 3 and supporting the converter 6. Since the support sleeve 2 is threadedly connected to the fixing seat 11 of the measuring tube 1, when maintenance or replacement of the detection probe 4 is required, simply unscrew the support sleeve 2 from the fixing seat 11, or disassemble the plug-in structure 7 and remove the detection probe 4 from the support sleeve 2, and the detection probe 4 can be removed from the measuring tube 1. Compared with the prior art, the disassembly and assembly of the detection probe 4 is simple, requires no tools, and enables quick repair or replacement of the detection probe 4.

[0043] In some embodiments, the fixing seat 11 and the support sleeve 2 can be connected by, for example, Figure 1 The structure shown is described in the following document. Figure 1 The fixed base 11 has an upward-facing mounting cavity, and the lower end of the support sleeve 2 is embedded in the mounting cavity; the outer wall of the support sleeve 2 is provided with an abutting ring 21; the abutting ring 21 abuts against the top surface of the fixed base 11.

[0044] The lower end of the support sleeve 2 has an external thread on its outer wall and an internal thread on its inner wall. The external thread and the internal thread are connected. The lower end of the support sleeve 2 is embedded in the mounting cavity. Compared with the method of sleeve 2 being fitted outside the fixed base 11, the support sleeve 2 can be installed manually more conveniently. In addition, the outer diameter of the support sleeve 2 can be reduced, thus reducing the manufacturing cost of the support sleeve 2.

[0045] When the support sleeve 2 is screwed into the mounting cavity, the abutting ring 21 abuts against the top surface of the fixed seat 11; the abutting ring 21 serves to seal the mounting cavity and also serves to indicate that the support sleeve 2 is screwed into place.

[0046] In some embodiments, the support sleeve 2 and the conduit 3 can be connected by, for example, Figure 1 The structure shown is described in the following document. Figure 1 The inner wall of the support sleeve 2 is provided with multiple limiting ring platforms 22 that are spaced apart along its axial direction; multiple limiting sleeves 31 are tightly fitted on the conduit 3, and the multiple limiting sleeves 31 are embedded in the multiple limiting ring platforms 22 one by one.

[0047] The limiting sleeve 31 is made of elastic material and has slight deformation capability. The limiting sleeve 31 is interference-fitted with the conduit 3, so it can be tightly fitted onto the conduit 3. The limiting sleeve 31 abuts radially against the corresponding limiting ring platform 22, and the conduit 3 is radially limited in the inner cavity of the support sleeve 2 by the limiting sleeve 31 to restrict swinging and ensure the stability of signal transmission.

[0048] It should be noted that when assembling the limiting sleeve 31 and the conduit 3, the limiting sleeve 31 needs to be installed into the corresponding limiting ring platform 22 first. Since the limiting sleeve 31 is made of elastic material and has slight deformation capability, the limiting sleeve 31 can axially pass through other limiting ring platforms 22 that do not correspond to it. Once it reaches the corresponding limiting ring platform 22, the limiting sleeve 31 will no longer move. Then, the conduit 3 is passed through multiple limiting sleeves 31.

[0049] Preferably, in this embodiment, two limiting sleeves 31 are provided, which are respectively fitted onto the upper and lower halves of the conduit 3.

[0050] Please see Figure 1 and Figure 2 Based on the above implementation method, the limiting sleeve 31 is a T-shaped rotating body structure, and the horizontal part of the limiting sleeve 31 abuts against the top surface of the limiting ring platform 22, and the vertical part of the limiting sleeve 31 abuts against the inner wall of the limiting ring platform 22.

[0051] It should be noted that the outer diameter of the lateral portion of the limiting sleeve 31 is smaller than the inner diameter of the supporting sleeve 2, but slightly larger than the inner diameter of the limiting ring platform 22. This allows the lateral portion of the limiting sleeve 31 to pass through the limiting ring platform 22 by compressing and deforming it. Since this embodiment only uses two limiting sleeves 31, only the lateral portion of the lower limiting sleeve 31 needs to pass through the upper limiting ring platform 22. The upper limiting sleeve 31 only needs its vertical portion to pass through the limiting ring platform 22.

[0052] The limiting sleeve 31 adopts a T-shaped rotating body structure. When no external force is applied, its lateral part abuts against the top surface of the limiting ring platform 22, and the two form a limit in the axial direction, thereby also being able to position the conduit 3 and the detection probe 4 in the axial direction.

[0053] In some embodiments, the lower limiting sleeve 31 may also adopt the following... Figure 2 The structure shown is described in the following document. Figure 2 The measuring tube 1 has a radially extending through hole 12 on its tube wall, and the lower end of the wire tube 3 is located inside the through hole 12; the bottom surface of the lower limiting sleeve 31 is in close contact with the outer wall of the measuring tube 1.

[0054] The through hole 12 is used to allow the detection probe 4 to extend into the inner cavity of the measuring tube 1. Since the support sleeve 2 is connected to the fixed base 11 by screwing, in order to ensure that the detection probe 4 can smoothly extend into or out of the inner cavity of the measuring tube 1, the inner diameter of the through hole 12 should be slightly larger than the outer diameter of the conduit 3, or the through hole 12 and the conduit 3 should also be connected by threads.

[0055] If the inner diameter of the through hole 12 is slightly larger than the outer diameter of the conduit 3, then the bottom surface of the lower limiting sleeve 31 will be in close contact with the outer wall of the measuring tube 1, which can also seal the through hole 12, thereby preventing the medium in the measuring tube 1 from overflowing through the through hole 12.

[0056] If the through hole 12 and the conduit 3 are connected by threads, the threaded connection can provide a first layer of sealing. The bottom surface of the lower limiting sleeve 31 is in close contact with the outer wall of the measuring tube 1, which can also provide a second layer of sealing, further improving the sealing effect of the through hole 12.

[0057] In some embodiments, the support sleeve 2 may also be as follows: Figure 1 The structure shown is described in the following document. Figure 1 The outer wall of the support sleeve 2 is provided with heat dissipation fins 23. The heat dissipation fins 23 are used to dissipate heat from the inner cavity of the support sleeve 2, so that the wide-range vortex flowmeter can be used in high-temperature environments.

[0058] In some embodiments, the conduit 3 and the detection probe can be adopted as follows: Figure 2 The structure shown is described in the following document. Figure 2 The lower end of the conduit 3 is provided with a slot, and the detection probe 4 is partially inserted into the slot.

[0059] The detection probe 4 is inserted into the conduit 3, which simplifies the assembly of the detection probe 4 and the conduit 3 and makes it easy to assemble and disassemble the detection probe 4 with the conduit 3.

[0060] Preferably, the detection probe 4 is electrically connected to the slot, that is, after the detection probe 4 is partially inserted into the slot, it can be electrically connected to the detection circuit inside the conduit 3.

[0061] In some embodiments, the connection between the conduit 3 and the converter 6 can be as follows: Figure 1 The structure shown is described in the following document. Figure 1 The upper end of the conduit 3 is provided with a socket 32, and the converter 6 is provided with a plug 61 inside, which is electrically connected to the socket 32.

[0062] The conduit 3 and the converter 6 are electrically connected by a plug 61 and a socket 32. On the one hand, this ensures the stability of the electrical connection between the conduit 3 and the converter 6; on the other hand, it also enables quick assembly and disassembly of the converter 6 and the conduit 3.

[0063] In some embodiments, the converter 6 and the support sleeve 2 can be connected by, for example, Figure 3 The structure shown is described in the following document. Figure 3 The upper end of the support sleeve 2 is provided with a second connecting platform 24 that protrudes outward in the radial direction, and the lower end of the converter 6 is provided with a first connecting platform 62 that protrudes outward in the radial direction; the first connecting platform 62 and the second connecting platform 24 abut against each other vertically; the plug-in structure 7 passes through the first connecting platform 62 and the second connecting platform 24 in the axial and radial directions.

[0064] Preferably, both the first connecting platform 62 and the second connecting platform 24 are annular structures, and two sets of plug-in structures 7 are provided between the first connecting platform 62 and the second connecting platform 24. The two sets of plug-in structures 7 are symmetrically arranged and the interval angle is 180°.

[0065] The plug-in structure 7 is inserted axially and radially between the first connecting platform 62 and the second connecting platform 24 to ensure that the support sleeve 2 is stable after being connected to the converter 6 and will not produce relative displacement.

[0066] Specifically, please refer to Figure 3 The first connecting platform 62 is provided with a first insertion hole 621 that extends through the axis, and the second connecting platform 24 is provided with a blind hole 241 that corresponds vertically to the first insertion hole 621. The second connecting platform 24 is also provided with a second insertion hole 242 that extends through the radial direction, and a guide groove 243 that communicates with the second insertion hole 242.

[0067] The plug-in structure 7 includes a first plug 71 and a second plug 72; the first plug 71 has a third plug hole 711 on its side wall; the second plug 72 has a slider 721; the first plug 71 is inserted downward into the first plug hole 621 and the blind hole 241; the second plug 72 passes through the second plug hole 242 and is inserted into the third plug hole 711, and the slider 721 is located in the guide groove 243.

[0068] When installing the plug-in structure 7, first insert the first plug 71 into the first socket 621 and the blind hole 241. The first socket 621 radially limits the first connecting platform 62 and the second connecting platform 24. Then, push the second plug 72 into the third socket 711. The second plug 72 axially limits the first plug 71, and thus axially limits the first connecting platform 62 and the second connecting platform 24. When disassembling the plug-in structure 7, first pull the second plug 72 outward to disengage it from the third socket 711, and then pull the first plug 71 upward to disengage it from the blind hole 241.

[0069] The above installation and disassembly process can be carried out manually. The operation is simple and quick, without the need for tools, and the converter 6 can be quickly installed and removed.

[0070] It should be noted that the second plug 72 is always partially located inside the second socket 242 and partially located outside the second connecting platform 24. The exposed part of the second plug 72 can be manually pulled or pushed to move the second plug 72 within the second socket 242 to insert into or detach from the third socket 711.

[0071] In addition, the second insertion block 72 is provided with a slider 721, and the second connecting platform 24 is also provided with a guide groove 243 communicating with the second insertion hole 242. The slider 721 is slidably disposed in the guide groove 243, which not only guides the movement direction of the second insertion block 72, but also restricts the first insertion block 71 from moving outward when the slider 721 slides to abut against the bottom wall of the guide groove 243, so as to prevent the second insertion block 72 from being pulled out of the second insertion hole 242 due to excessive force.

[0072] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A wide range vortex flowmeter characterized by, The utility model relates to a kind of vortex shedding flowmeter, including: Measuring tube (1) for being connected with the pipeline to be measured;The inside of the measuring tube (1) is equipped with vortex generator (5);The outer wall of the measuring tube (1) is equipped with fixed seat (11); Support sleeve (2), lower end is threadedly connected with the fixed seat (11); Wire pipe (3) is arranged in the inside of the support sleeve (2);The lower end of the wire pipe (3) is connected with detection probe (4), and the detection probe (4) extends into the measuring tube (1), and is located downstream of the vortex generator (5); And Converter (6) is detachably connected with the upper end of the support sleeve (2) by plug-in structure (7), and is electrically plugged with the upper end of the wire pipe (3).

2. The wide range vortex flowmeter of claim 1 wherein, The fixed seat (11) has an installation cavity with an opening facing upward, and the lower end of the support sleeve (2) is embedded in the installation cavity; the outer wall of the support sleeve (2) is provided with an abutting ring table (21); the abutting ring table (21) abuts against the top surface of the fixed seat (11).

3. The wide range vortex flowmeter of claim 1 wherein, The inner wall of the support sleeve (2) is provided with a plurality of limiting ring tables (22) spaced along the axial direction thereof; the wire pipe (3) is tightly sleeved with a plurality of limiting sleeves (31), and the plurality of limiting sleeves (31) are one-to-one correspondingly embedded in the plurality of limiting ring tables (22).

4. The wide range vortex flowmeter of claim 3 wherein, The limiting sleeve (31) is a T-shaped rotary body structure, and the transverse part of the limiting sleeve (31) abuts against the top surface of the limiting ring table (22), and the vertical part of the limiting sleeve (31) abuts against the inner wall of the limiting ring table (22).

5. The wide range vortex flowmeter of claim 3 wherein, The pipe wall of the measuring tube (1) is provided with a through hole (12) extending in the radial direction, and the lower end of the wire pipe (3) is located in the through hole (12); wherein the bottom surface of the lower limiting sleeve (31) tightly abuts against the outer wall of the measuring tube (1).

6. The wide range vortex flowmeter of claim 1, wherein, The outer wall of the support sleeve (2) is provided with a heat dissipation fin (23).

7. The wide range vortex flowmeter of claim 1 wherein, The lower end of the wire pipe (3) is provided with a slot, and the detection probe (4) is partially inserted into the slot.

8. The wide range vortex flowmeter of claim 1 wherein, The upper end of the wire pipe (3) is provided with a socket (32), and the inside of the converter (6) is provided with a plug (61), which is electrically plugged with the socket (32).

9. The wide range vortex flowmeter of claim 1 wherein, The lower end of the converter (6) is provided with a first connecting table (62) protruding outward in the radial direction, and the upper end of the support sleeve (2) is provided with a second connecting table (24) protruding outward in the radial direction, and the first connecting table (62) and the second connecting table (24) abut against each other; the plug-in structure (7) is axially and radially arranged between the first connecting table (62) and the second connecting table (24).

10. The wide range vortex flowmeter of claim 9 wherein, The first connecting table (62) is provided with a first insertion hole (621) penetrating in the axial direction, and the second connecting table (24) is provided with a blind hole (241) corresponding to the first insertion hole (621) above and below; the second connecting table (24) is further provided with a second insertion hole (242) penetrating in the radial direction, and a guide groove (243) communicating with the second insertion hole (242). The plug structure (7) comprises a first plug block (71) and a second plug block (72); a third insertion hole (711) is arranged on the side wall of the first plug block (71); a sliding block (721) is arranged on the second plug block (72); The first plug block (71) is inserted into the first insertion hole (621) and the blind hole (241); the second plug block (72) passes through the second insertion hole (242) and is inserted into the third insertion hole (711), and the sliding block (721) is located in the guide groove (243).

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