CN217087428U

CN217087428U - Prefabricated junction box

Info

Publication number: CN217087428U
Application number: CN202123024829.XU
Authority: CN
Inventors: 杨佩桥; 李振东; 刘晓忠; 孙远强; 王静波; 王成; 蒋斌文; 徐璟莉; 蒋建福; 李向玉; 杨亚静; 杨锋; 杨晶晶; 俞贤文; 景勇
Original assignee: Zhongwei Power Supply Company State Grid Ningxia Electric Power Co ltd
Current assignee: Zhongwei Power Supply Company State Grid Ningxia Electric Power Co ltd
Priority date: 2021-12-03
Filing date: 2021-12-03
Publication date: 2022-07-29
Anticipated expiration: 2031-12-03

Abstract

The utility model provides a prefabricated terminal box, this prefabricated terminal box includes: a box body; the wiring terminal block is arranged in the box body; the current and voltage acquisition module is provided with a first wire harness, one end of the first wire harness, which is far away from the current and voltage acquisition module, is used for extending into the box body and is connected with the wiring terminal strip, and the current and voltage acquisition module is electrically connected with the wiring terminal strip through the first wire harness; the signal output module is provided with a second wire harness, one end, far away from the signal output module, of the second wire harness is used for extending into the box body and is connected with the wiring terminal strip, and the signal output module is electrically connected with the wiring terminal strip through the second wire harness. This prefabricated terminal box realizes that the prefabrication integrates, has unified the wiring standard to effectively reduced artifical wrong probability of wiring, improved telemetering measurement debugging accuracy, improved telemetering measurement debugging efficiency simultaneously.

Description

Prefabricated junction box

Technical Field

The utility model relates to a technical field of telemetering measurement especially relates to a prefabricated terminal box.

Background

With the development of the distribution internet of things, the intelligent integration terminal of the transformer area starts large-scale installation and coverage, and when the intelligent integration terminal of the transformer area is installed and debugged, the intelligent integration terminal of the transformer area needs to be telemetered and debugged.

At present, the remote measurement and debugging of the intelligent fusion terminal in the transformer area are carried out in a field wiring mode, but due to the fact that the current transformer windings of different distribution transformer cabinets are different in configuration, the wiring sequence and the wiring path need to be judged on site, the requirement on workers is high, the field operation is complex, the remote measurement and debugging efficiency of the intelligent fusion terminal in the transformer area is affected, and in addition, the accuracy of remote measurement and debugging data is affected due to the fact that current short circuit errors are prone to occur in the wiring process.

Through the technical analysis, the defects of field wiring, complex operation and influence on the remote measurement and debugging efficiency of the intelligent fusion terminal in the transformer area exist in the prior art.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a prefabricated terminal box to solve prior art field connection, the operation is more complicated, influences the defect of the efficiency of district intelligent integration terminal telemetering measurement debugging.

An embodiment of the utility model provides a prefabricated terminal box, include:

a box body;

the wiring terminal block is arranged in the box body;

the current and voltage acquisition module is provided with a first wiring harness, one end of the first wiring harness, which is far away from the current and voltage acquisition module, is used for extending into the box body and connecting with the wiring terminal block, and the current and voltage acquisition module is electrically connected with the wiring terminal block through the first wiring harness;

the signal output module is provided with a second wire harness, one end, far away from the signal output module, of the second wire harness is used for extending into the box body and is connected with the wiring terminal row, and the signal output module is electrically connected with the wiring terminal row through the second wire harness.

The utility model has the advantages that: the wiring terminal strip that sets up can realize integrating the secondary circuit and connect for voltage data and the electric current data transmission that current-voltage collection module gathered are arranged to wiring terminal, can arrange through signal output module output by wiring terminal, do not need the manual work to carry out the on-the-spot wiring, only need install current-voltage collection module can, convenient operation is simple, and is low to operation workman's requirement, can also improve telemetering measurement debugging efficiency. The prefabricated junction box realizes prefabricated integration and unifies wiring standards, thereby effectively reducing the probability of manual wiring errors and improving the accuracy of remote measurement debugging.

On the basis of the technical scheme, the utility model discloses can also do following improvement.

Further, the current and voltage acquisition module comprises a current transformer and a voltage connector, and the first wire harness is respectively electrically connected with the current transformer and the voltage connector.

The beneficial effect of adopting the further scheme is that: the current data and the voltage data are convenient to acquire.

Furthermore, binding post row includes a plurality of input terminal and a plurality of output terminal, and is a plurality of input terminal sets up side by side, and is a plurality of output terminal sets up side by side, first pencil is kept away from the one end of current and voltage collection module is respectively with a plurality of input terminal is connected, the second pencil is kept away from the one end of signal output module is respectively with a plurality of output terminal is connected.

The beneficial effect of adopting the above further scheme is: the input current voltage data and the output current voltage data are convenient.

Furthermore, a first wiring port and a second wiring port are formed in the box body, one end, far away from the current and voltage acquisition module, of the first wiring harness penetrates through the first wiring port and stretches into the box body, and one end, far away from the signal output module, of the second wiring harness penetrates through the second wiring port and stretches into the box body.

The beneficial effect of adopting the further scheme is that: the first wire harness and the second wire harness are conveniently stretched into the box body to be connected with the wiring terminal block.

Further, be provided with first gluey ring in the first wiring mouth, first pencil passes first gluey ring, the inner annular wall of first gluey ring with the outer wall of first pencil supports, first gluey ring is used for sealing first pencil with the clearance between the first wiring mouth, be provided with the second in the second wiring mouth and glue the ring, the second pencil passes the second glues the ring, the inner annular wall of second gluey ring with the outer wall of second pencil supports, the second glues the ring and is used for sealing the second pencil with the clearance between the second wiring mouth.

The beneficial effect of adopting the further scheme is that: can realize sealed waterproof through first gluey ring and second gluey ring.

Furthermore, a voltage detection port is arranged on the box body, the voltage detection port is electrically connected with the wiring terminal strip, and the voltage detection port is used for being electrically connected with an external telemeter.

The beneficial effect of adopting the further scheme is that: the voltage detection and power supply can be realized.

Furthermore, prefabricated terminal box still includes ground connection copper sheet and earth connection, the earth connection is connected on the ground connection copper sheet, the earth connection is kept away from the one end of ground connection copper sheet penetrates in the box body and with binding post row electricity is connected.

The beneficial effect of adopting the above further scheme is: can ground connection, avoid the incident to take place.

Further, the box body comprises a lower shell and an upper cover, and the upper cover is covered on the lower shell.

The beneficial effect of adopting the further scheme is that: can conveniently overhaul.

Furthermore, a plurality of threaded holes are formed in the lower shell, the threaded holes are distributed in an annular shape, a plurality of screws are arranged on the upper cover and correspond to the threaded holes one to one, and each screw can be in threaded fit with the corresponding threaded hole.

The beneficial effect of adopting the further scheme is that: the upper cover and the lower shell are connected conveniently.

Furthermore, a sealing washer is arranged on each threaded hole, and the screw penetrates through the sealing washer; an annular sealing groove is formed in the upper end face of the lower shell, a sealing rubber ring is arranged in the sealing groove, an annular protruding block is formed at the bottom end of the upper cover, and the protruding block is used for being clamped into the sealing groove and abutting against the sealing rubber ring.

The beneficial effect of adopting the further scheme is that: can improve the sealing and waterproof performance and prolong the service life.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.

Fig. 1 is a schematic structural view of a prefabricated junction box according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a lower housing according to an embodiment of the present invention.

In the drawings, the components represented by the respective reference numerals are listed below:

1. the upper cover, 2, voltage detection port, 3, first wiring mouth, 4, first pencil, 5, current transformer, 6, second wiring mouth, 7, second pencil, 8, signal output module, 9, lower casing, 10, first gluey ring, 11, seal groove, 12, sealed rubber ring, 13, screw hole, 14, bear the weight of the groove, 15, seal ring, 16, binding post row, 17, mount pad, 18, second gluey ring, 19, ground connection copper sheet, 20, earth connection, 21, third wiring mouth, 22, voltage connection head.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

As shown in fig. 1 and 2, the present disclosure provides a prefabricated junction box comprising: the terminal block comprises a box body, a terminal block 16, a current and voltage acquisition module and a signal output module 8.

The terminal block 16 is arranged in the housing. Be provided with first pencil 4 on the current-voltage collection module, the one end that current-voltage collection module was kept away from to first pencil 4 is used for stretching into in the box body and is connected with binding post row 16, and current-voltage collection module is connected with binding post row 16 electricity through first pencil 4. The signal output module 8 is provided with a second wire harness 7, one end of the second wire harness 7, which is far away from the signal output module 8, is used for extending into the box body and is connected with the wiring terminal block 16, and the signal output module 8 is electrically connected with the wiring terminal block 16 through the second wire harness 7.

Wherein, the box body is used for installing binding post row 16 for first pencil 4 and second pencil 7 are located the box body with binding post row 16's being connected, realize the prefabrication wiring, and can protect first pencil 4 and second pencil 7 and binding post row 16's junction, avoid receiving external influence and appear droing. The current and voltage acquisition module can acquire voltage data and current data of the distribution transformer. The signal output module 8 is used for being electrically connected with the intelligent transformer area fusion terminal, so that voltage data and current data are transmitted to the intelligent transformer area fusion terminal to achieve remote measurement debugging, and intelligent monitoring and expanding application of distribution transformer are achieved.

Among the above-mentioned technical scheme, 16 can realize integrating the secondary circuit through the binding post row that sets up and connect for voltage data and the electric current data transmission that current-voltage collection module gathered to binding post row 16 can be exported through signal output module 8 by binding post row 16, do not need the manual work to carry out the on-the-spot wiring, only need install current-voltage collection module can, convenient operation is simple, and is low to operation workman's requirement, can also improve telemetering measurement debugging efficiency. The prefabricated junction box realizes prefabricated integration and unifies wiring standards, thereby effectively reducing the probability of manual wiring errors and improving the accuracy of remote measurement debugging.

Optionally, in an embodiment of the present disclosure, the current and voltage collecting module includes a current transformer 5 and a voltage connector 22, and the first harness 4 is electrically connected to the current transformer 5 and the voltage connector 22, respectively.

In the present embodiment, the current transformer 5 is used for collecting current data, and the voltage connector 22 is used for collecting voltage data. The current data collected by the current transformer 5 and the voltage data collected by the voltage connector 22 can be transmitted to the terminal block 16 via the first harness 4, respectively.

Specifically, in the present embodiment, the number of the current transformers 5 is three, and all three current transformers 5 are open current transformers 5, and the open current transformers 5 can be connected to a distribution transformer low-voltage cable in a hanging manner, and can collect three-phase current telemetry data on a distribution transformer low-voltage side. Specifically, the three current transformers 5 are an a-phase current transformer 5, a B-phase current transformer 5, and a C-phase current transformer 5, respectively. The phase-a current transformer 5, the phase-B current transformer 5 and the phase-C current transformer 5 each have a first polarity end and a second polarity end. The first bundle 4 comprises 6 strands of 4mm ² Secondary line of BVR type. 6 pieces of 4mm ² One end of the BVR type secondary line is respectively connected with the first polarity end and the second polarity end of the A-phase current transformer 5, the B-phase current transformer 5 and the C-

phase current transformer

5, 6 lines of secondary lines with the thickness of 4mm are arranged ² The other end of the BVR type secondary wire is connected to the terminal block 16.

Specifically, in the present embodiment, the number of the voltage connectors 22 is four, and the first harness 4 further includes 4 pieces of 2.5mm ² Secondary line of BVR type, 4 lines 2.5mm ² One end of the BVR type secondary line is connected with four voltage connectors 22, 4 lines with 2.5mm ² The other end of the BVR type secondary wire is connected to the terminal block 16.

Specifically, in the present embodiment, the first harness 4 is heat-shrunk and has a fireproof and wear-resistant function.

Optionally, in an embodiment of the present disclosure, the terminal block 16 includes a plurality of input terminals and a plurality of output terminals, the plurality of input terminals are arranged in parallel, the plurality of output terminals are arranged in parallel, an end of the first wire harness 4 away from the current and voltage collecting module is connected to the plurality of input terminals, respectively, and an end of the second wire harness 7 away from the signal output module 8 is connected to the plurality of output terminals, respectively.

In the present embodiment, the input terminals and the output terminals are symmetrically distributed about the central axis, the number of the input terminals is 14, and the number of the output terminals is the same14 in number. The input terminals have reference numbers 1a-14a in the order from top to bottom. Wherein, 4 pieces of the above embodiment are 2.5mm ² BVR type secondary wires are connected to 1a-4a, 6 pieces of 4mm in the above embodiment ² The BVR type secondary wires are connected to 6a-11a, respectively, with 13a and 14b being spare terminals. Wherein, the output terminal is also provided with a reference number which is 1b-14b respectively according to the sequence from top to bottom. Wherein 9b-11b is provided with a first current communication tab to enable current communication 9b-11b, and 13b-14b is provided with a second current communication tab to enable

current communication

13b and 14 b. Specifically, in the present embodiment, the input terminal and the output terminal are both phoenix ac test terminals.

Specifically, in the present embodiment, the terminal block 16 is provided with a plurality of mounting seats 17, and the mounting seats 17 are connected to the inner wall of the box body in a snap-fit manner.

Optionally, in an embodiment of the present disclosure, a first wiring port 3 and a second wiring port 6 are formed in the box body, one end of the first wire harness 4, which is far away from the current and voltage collecting module, passes through the first wiring port 3 and extends into the box body, and one end of the second wire harness 7, which is far away from the signal output module 8, passes through the second wiring port 6 and extends into the box body.

Wherein, in this embodiment, first wiring mouth 3 and second wiring mouth 6 all communicate with the inside of box body for first pencil 4 and second pencil 7 can penetrate to the box body in. Specifically, first wiring mouth 3 and second wiring mouth 6 are located the both sides of box body respectively, make things convenient for current and voltage collection module and signal output module 8 to carry out erection joint respectively.

Optionally, in an embodiment of the present disclosure, a first rubber ring 10 is disposed in the first wire connection port 3, the first wire harness 4 passes through the first rubber ring 10, an inner annular wall of the first rubber ring 10 abuts against an outer wall of the first wire harness 4, the first rubber ring 10 is configured to seal a gap between the first wire harness 4 and the first wire connection port 3, a second rubber ring 18 is disposed in the second wire connection port 6, the second wire harness 7 passes through the second rubber ring 18, an inner annular wall of the second rubber ring 18 abuts against an outer wall of the second wire harness 7, and the second rubber ring 18 is configured to seal a gap between the second wire harness 7 and the second wire connection port 6.

In the embodiment, the first rubber ring 10 is fixedly connected in the first wire connection port 3, the outer ring wall of the first rubber ring 10 is connected with the inner wall of the first wire connection port 3, the first wire harness 4 passes through the first rubber ring 10, and the gap between the first wire harness 4 and the inner wall of the first wire connection port 3 is sealed through the first rubber ring 10, so that the sealing and waterproof performance is ensured. It can be understood that the first rubber ring 10 has elasticity, and when the first string 4 passes through the first rubber ring 10, the first rubber ring 10 is spread, so that the inner annular wall of the first rubber ring 10 abuts against the outer wall of the first string 4, and the tight fit is realized.

In the present embodiment, the second rubber ring 18 is fixedly connected inside the second wire connection port 6, the outer annular wall of the second rubber ring 18 is connected to the inner wall of the second wire connection port 6, the second wire harness 7 passes through the second rubber ring 18, and the second rubber ring 18 seals the gap between the second wire harness 7 and the inner wall of the second wire connection port 6, so as to ensure the sealing and waterproof performance. It can be understood that the second rubber ring 18 has elasticity, and when the second wire harness 7 passes through the second rubber ring 18, the second rubber ring 18 is spread, so that the inner annular wall of the second rubber ring 18 abuts against the outer wall of the second wire harness 7, and a tight fit is realized.

Optionally, in an embodiment of the present disclosure, a voltage detection port 8 is disposed on the box body, the voltage detection port 8 is electrically connected to the terminal block 16, and the voltage detection port 8 is used for being electrically connected to an external telemeter.

In the present embodiment, the voltage detection port 8 is located at the top end of the case, and the voltage detection port 8 is connected to the input terminals 1a to 4a in the above-described embodiment. So that the voltage detection port 8 can detect the voltage of the input terminals 1a-4 a. The voltage detection port 8 is electrically connected with an external telemeter through a lead.

Optionally, in an embodiment of the present disclosure, the prefabricated junction box further includes a grounding copper sheet 19 and a grounding wire 20, the grounding wire 20 is connected to the grounding copper sheet 19, and an end of the grounding wire 20 away from the grounding copper sheet 19 penetrates into the box body and is electrically connected to the terminal block 16.

In the embodiment, the grounding copper sheet 19 is placed on the ground or the wall surface to realize grounding, the grounding wire 20 is used for realizing grounding current transmission, and the grounding can be performed through the grounding copper sheet 19 and the grounding wire 20, so that the safety problem is avoided. Wherein, a third wiring port 21 is arranged on the box body, and one end of the grounding wire 20 far away from the grounding copper sheet 19 passes through the third wiring port 21 and extends into the box body. A third rubber ring is also arranged in the corresponding third wiring port 21, so that the sealing effect can be realized.

Optionally, in an embodiment of the present disclosure, the box body includes a lower housing 9 and an upper cover 1, and the upper cover 1 is covered on the lower housing 9.

In this embodiment, the lower housing 9 is rectangular, and the top end of the lower housing 9 is open for installing the terminal strip 16. In which the terminal block 16 is located in the lower housing 9, and the first, second and

third connection ports

3, 6, 21 in the above-described embodiment are all located on the lower housing 9. The upper cover 1 covers the lower casing 9 to close the opening of the lower casing 9. The upper cover 1 is detachably connected with the lower shell 9, and can be conveniently overhauled. Specifically, the upper cover 1 and the lower housing 9 are made of ABS material. The upper cover 1 can be pasted with a two-dimensional code of a manufactured operation specification, so that field workers can conveniently install and use the operation specification.

Optionally, in an embodiment of the present disclosure, a plurality of threaded holes 13 are formed in the lower housing 9, the plurality of threaded holes 13 are distributed in an annular shape, a plurality of screws are arranged on the upper cover 1, the plurality of screws correspond to the plurality of threaded holes 13 one to one, and each screw can be in threaded fit with the corresponding threaded hole 13.

In the present embodiment, the screw provided is matched with the threaded hole 13, so that the connection between the upper cover 1 and the lower housing 9 can be facilitated. Specifically, the number of the threaded holes 13 is 4, the 4 threaded holes 13 are located at four corners of the lower housing 9, the number of the corresponding screws is also 4, and the screws are located at four corners of the upper cover 1.

Optionally, in one embodiment of the present disclosure, a sealing washer 15 is disposed on each threaded hole 13, and a screw passes through the sealing washer 15. An annular sealing groove 11 is formed in the upper end face of the lower shell 9, a sealing rubber ring 12 is arranged in the sealing groove 11, an annular protruding block is formed at the bottom end of the upper cover 1, and the protruding block is clamped into the sealing groove 11 and abuts against the sealing rubber ring 12.

In this embodiment, the sealing gasket 15 can seal the joint between the screw and the threaded hole 13, thereby improving the sealing and waterproof performance. Specifically, a bearing groove 14 is formed at the opening of each threaded hole 13, and the sealing gasket 15 is placed in the bearing groove 14, so that the sealing performance can be prevented from being influenced by the displacement of the sealing gasket 15. The sealing washer 15 may be a rubber ring.

Wherein, among this embodiment, seal groove 11 carries out the annular along the edge of the up end of casing 9 down and extends, and the corresponding lug carries out the annular along the edge of upper cover 1 bottom and extends for sealed rubber ring 12 can seal the junction of casing 9 and upper cover 1 down, can effectively improve sealed waterproof performance.

Optionally, in an embodiment of the present disclosure, the signal output module 8 is a dedicated aviation plug, which includes 12 cores and can match with an aviation socket on the platform intelligent convergence terminal.

Optionally, in an embodiment of the present disclosure, the second wire harness 7 includes 12 4mm wires ² Secondary line of BVR type. The second wire harness 7 is formed by heat shrinkage and has fireproof and wear-resistant performance. 12 pieces of 4mm ² The BVR type secondary wires are connected to 1b-4b, 5b-11b and 13b-14b of the above embodiments, respectively.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A prefabricated junction box, comprising:

a box body;

the wiring terminal block (16), the wiring terminal block (16) is arranged in the box body;

the current and voltage acquisition module is provided with a first wiring harness (4), one end, far away from the current and voltage acquisition module, of the first wiring harness (4) is used for extending into the box body and is connected with the wiring terminal row (16), and the current and voltage acquisition module is electrically connected with the wiring terminal row (16) through the first wiring harness (4);

the signal output module (8), be provided with second pencil (7) on the signal output module (8), second pencil (7) are kept away from the one end of signal output module (8) is used for stretching into in the box body and with binding post row (16) are connected, signal output module (8) pass through second pencil (7) with binding post row (16) electricity is connected.

2. Prefabricated junction box according to claim 1, characterized in that said current and voltage acquisition module comprises a current transformer (5) and a voltage connector (22), said first wiring harness (4) being electrically connected with said current transformer (5) and said voltage connector (22), respectively.

3. The prefabricated junction box according to claim 1, wherein said terminal block (16) comprises a plurality of input terminals and a plurality of output terminals, said plurality of input terminals being juxtaposed, said plurality of output terminals being juxtaposed, an end of said first wire harness (4) remote from said current and voltage acquisition module being connected to said plurality of input terminals, respectively, an end of said second wire harness (7) remote from said signal output module (8) being connected to said plurality of output terminals, respectively.

4. The prefabricated junction box of claim 1, wherein a first junction port (3) and a second junction port (6) are formed in the box body, one end, far away from the current and voltage acquisition module, of the first wiring harness (4) penetrates through the first junction port (3) and extends into the box body, and one end, far away from the signal output module (8), of the second wiring harness (7) penetrates through the second junction port (6) and extends into the box body.

5. The prefabricated junction box according to claim 4, wherein a first glue ring (10) is arranged in the first wiring opening (3), the first wiring harness (4) penetrates through the first glue ring (10), an inner ring wall of the first glue ring (10) abuts against an outer wall of the first wiring harness (4), the first glue ring (10) is used for sealing a gap between the first wiring harness (4) and the first wiring opening (3), a second glue ring (18) is arranged in the second wiring opening (6), the second wiring harness (7) penetrates through the second glue ring (18), an inner ring wall of the second glue ring (18) abuts against an outer wall of the second wiring harness (7), and the second glue ring (18) is used for sealing a gap between the second wiring opening (7) and the second wiring opening (6).

6. Prefabricated junction box according to claim 1, characterized in that a voltage detection port (2) is provided on said box, said voltage detection port (2) being electrically connected to said terminal block (16), said voltage detection port (2) being intended to be electrically connected to an external telemeter.

7. The prefabricated junction box of claim 1, further comprising a grounding copper sheet (19) and a grounding wire (20), wherein the grounding wire (20) is connected to the grounding copper sheet (19), and one end of the grounding wire (20) far away from the grounding copper sheet (19) penetrates into the box body and is electrically connected with the terminal block (16).

8. Prefabricated junction box according to any of claims 1 to 7, characterized in that said box comprises a lower casing and an upper cover (1), said upper cover (1) being placed on said lower casing.

9. The prefabricated junction box of claim 8, wherein a plurality of threaded holes (13) are formed in the lower shell, the plurality of threaded holes (13) are distributed annularly, a plurality of screws are arranged on the upper cover (1), the plurality of screws correspond to the plurality of threaded holes (13) one by one, and each screw can be in threaded fit with the corresponding threaded hole (13).

10. Prefabricated junction box according to claim 9, characterized in that a sealing washer (15) is provided on each threaded hole (13), said screw passing through said sealing washer (15); an annular sealing groove (11) is formed in the upper end face of the lower shell, a sealing rubber ring (12) is arranged in the sealing groove (11), an annular protruding block is formed at the bottom end of the upper cover (1), and the protruding block is used for being clamped into the sealing groove (11) and abutting against the sealing rubber ring (12).