Test switch

Abstract

The utility model relates to a test switch which comprises a shell, a relay protection loop and a signal loop, the relay protection loop and the signal loop are arranged in the shell, the relay protection loop and the signal loop are electrically connected, and a microswitch is arranged in the shell; the shell is provided with a test hole, and the test hole is provided with a test connector electrically connected with a relay protection loop; a mounting base connected to a top cover of the shell is arranged in the shell, a lifting base is arranged on the side, facing the bottom of the shell, of the mounting base in a lifting mode, and an operation fulcrum used for touching a switch elastic piece of the microswitch is arranged on the lifting base. And the mounting seat is provided with a mode switching mechanism which is used for driving the lifting seat to lift so as to enable the operation fulcrum to be in contact with a switch elastic sheet of the microswitch, thereby triggering the test switch to be switched into a test mode / working mode. According to the invention, the test switch can be flexibly switched between the test mode and the working mode, and the practicability and functionality of the test switch are improved.

Description

Technical Field

[0001] This application relates to the technical field of relay protection control circuit testing, and in particular to a test switch. Background Technology

[0002] Test switches are used in relay protection control circuits and are used in conjunction with test plugs. They can quickly isolate the relay protection circuit and its input sides (voltage, current, auxiliary power supply, etc.) and trip signal circuits, and ensure reliable short-circuiting of external current transformers (CTs), facilitating the verification of protection devices.

[0003] Most commonly used test switches disconnect the signal circuit from the relay protection circuit during normal operation by inserting a test plug, and then connect the test signal to the protection device. That is, the signal circuit and the relay protection circuit remain normally closed. When switching to test mode, a special plug is used to connect an external test signal, and the connection between the signal circuit and the relay protection circuit is disconnected. This method is not only cumbersome but also increases equipment maintenance costs, resulting in low practicality. Utility Model Content

[0004] The purpose of this application is to provide a test switch that enables flexible switching between test mode and working mode, thereby improving the practicality and functionality of the test switch.

[0005] This utility model is achieved through the following technical solution:

[0006] A test switch includes a housing and a relay protection circuit and a signal circuit disposed within the housing, the relay protection circuit and the signal circuit being electrically connected. A microswitch for controlling the on / off connection between the relay protection circuit and the signal circuit is disposed within the housing. A test hole is provided on the housing, and a test connector electrically connected to the relay protection circuit is provided within the test hole. A mounting base connected to the top cover of the housing is disposed within the housing. A lifting seat is movably disposed on the side of the mounting base facing the bottom of the housing. The lifting seat has an operating fulcrum for contacting the switch spring of the microswitch. A mode switching mechanism is provided on the mounting base for driving the lifting seat to move up and down so that the operating fulcrum contacts the switch spring of the microswitch, thereby triggering the test switch to switch to test mode / operating mode.

[0007] Preferably, the mounting base is provided with a limiting platform, and the limiting platform is provided with a limiting guide rail that is slidably connected to the lifting base.

[0008] Preferably, a support spring for supporting the lifting seat is provided between the lifting seat and the micro switch.

[0009] Preferably, the mode switching mechanism includes a groove formed on the upper surface of the mounting base, a slider slidably disposed in the groove, and a driving component for driving the slider to slide horizontally within the groove. The bottom of the groove has a through hole penetrating the bottom of the mounting base. A cylinder is provided on the lifting base. The top of the cylinder is spherical and extends into the groove through the through hole. The slider has a through hole that mates with the through hole. The spherical apex of the top of the cylinder is located within the through hole.

[0010] Preferably, the driving assembly includes a turntable rotatably mounted on the mounting base and a rotating component for driving the turntable to rotate. The upper surface of the mounting base is also provided with a rotating groove for accommodating the turntable. The rotating groove communicates with a sliding groove. The edge of the turntable is provided with a gear slot. The gear slot is divided into a test gear slot and a working gear slot. The test gear slot and the working gear slot correspond to the test mode and the working mode, respectively. The test gear slot and the working gear slot are arranged adjacent to each other, and the adjacent parts of the test gear slot and the working gear slot are rounded. A stop block is provided at one end of the slider near the rotating groove. The stop block is inserted into the gear slot, and the end of the stop block abuts and slides against the groove walls of both the test gear slot and the working gear slot.

[0011] Preferably, a return spring is also provided in the slide groove, one end of which abuts against the end of the slider away from the stop block, and the other end abuts against the groove wall on the side of the slide groove facing the rotating groove.

[0012] Preferably, the rotating component includes a knob rotatably mounted on the top cover of the housing, the knob having a rotating shaft that passes vertically downward through the axis of the turntable and is fixedly connected to the turntable.

[0013] Preferably, the top of the housing is provided with a protective cover for covering the knob.

[0014] Preferably, the housing has an opening at the bottom, a base is provided at the bottom of the housing, an elastic buckle is provided on the base, and a snap hole is provided on the side wall of the housing to engage with the elastic buckle.

[0015] In summary, this application has the following beneficial effects:

[0016] 1. The lifting seat is driven by the mode switching mechanism to make contact or disconnect the operating fulcrum with the switch spring of the micro switch, so as to efficiently realize the flexible switching of the test switch between the test mode and the working mode.

[0017] 2. The test connectors configured with the test holes can use universal plugs and sockets, which enhances the versatility of the test harness and reduces equipment maintenance costs and workload. Attached Figure Description

[0018] Figure 1This is a logic circuit diagram of the micro switch controlling the on / off state of the relay protection circuit and the signal circuit in the embodiments of this application.

[0019] Figure 2 This is a schematic diagram of the overall structure of the test switch in an embodiment of this application.

[0020] Figure 3 This is a schematic diagram of the assembly relationship between the base and the housing in an embodiment of this application.

[0021] Figure 4 This is a partial cross-sectional view of an embodiment of this application.

[0022] Figure 5 This is a schematic diagram illustrating the relationship between the mode switching mechanism, the lifting seat, and the micro switch in the embodiments of this application.

[0023] Figure 6 This is a schematic diagram of the mode switching mechanism in the embodiments of this application.

[0024] Figure 7 This is a partial cross-sectional view of the mounting base in an embodiment of this application.

[0025] Figure 8 This is a schematic diagram of the structure of the protective cover in the embodiments of this application.

[0026] In the picture:

[0027] 1. Housing; 101. Snap-hole; 102. Test hole; 2. Protective cover; 21. Limiting groove; 3. Base; 31. Elastic buckle; 4. Micro switch; 41. Switch spring; 5. Mounting base; 51. Limiting platform; 52. Limiting guide rail; 53. Slide groove; 531. Sliding part; 532. Clearing part; 54. Slider; 541. Through hole; 542. Stop block; 543. Guide post; 55. Through hole; 56. Rotating groove; 57. Turntable; 571. Gear groove; 5711. Working gear groove; 5712. Test gear groove; 58. Return spring; 59. Cover; 6. Lifting seat; 61. Column; 62. Operating fulcrum; 63. Cylinder; 7. Support spring; 8. Knob. Detailed Implementation

[0028] The following will be combined with the appendix Figure 1-8 The technical solutions in the embodiments of this application are clearly and completely described. The described embodiments are only possible technical implementations of the present invention, and not all possible implementations. Those skilled in the art can, in conjunction with the embodiments of the present invention, obtain other embodiments without creative effort, and these embodiments are also within the protection scope of the present invention. A test switch, referred to... Figure 1 and Figure 2It includes a housing 1 with an opening at the bottom, and a relay protection circuit and a signal circuit disposed within the housing 1, which are electrically connected. The housing 1 is hollow and cuboid in shape, and a protective cover 2 is provided on the top of the housing 1.

[0029] Reference Figure 3 The bottom of the housing 1 is detachably fitted with a base 3 for sealing the bottom opening. Two sets of elastic clips 31 are symmetrically distributed on two opposite sides of the base 3. The sidewalls of the housing 1 have corresponding locking holes 101 that engage with the elastic clips 31. A test hole 102 is provided at the top of the housing 1. A test connector electrically connected to the relay protection circuit inside the housing 1 is located within the test hole 102. This test connector is used to connect to an external test connector, thereby outputting an external test signal to the relay protection circuit. In this embodiment, the test hole 102 extends vertically downwards into the housing 1. The housing 1 contains microswitches 4 for controlling the on / off state of the relay protection circuit and the signal circuit. The microswitches 4 are monostable microswitches. There are four sets of microswitches 4 arranged side-by-side on the base 3. The microswitches 4 are fixed to the base 3 with screws, and their contacts face upwards. The number of microswitches 4 is not limited.

[0030] Specifically, refer to Figure 1 and Figure 3 Each microswitch 4 has two sets of contacts, which are spring-loaded contacts, symmetrically distributed on both sides of the microswitch 4. The two sets of contacts are normally closed contacts and normally open contacts. Each microswitch 4 has a switch spring 41 that contacts the normally closed and normally open contacts respectively. The switch spring 41 is divided into a normally open portion and a normally closed portion. The normally open portion, when paired with the normally open contact, forms a normally open contact switch km-1, and the normally closed portion, when paired with the normally closed contact, forms a normally closed contact switch km-2. A connecting portion is formed between the normally open and normally closed portions, rotatably connected to the surface of the microswitch 4, so that when the normally open portion is pressed down to close the normally open contact switch km-1, the normally closed contact switch km-2 can open with the rotation of the switch spring 41.

[0031] Reference Figure 1When the test switch is in operating mode, when the normally open part touches and presses the normally open contact, that is, when the normally open contact switch km-1 closes and the normally closed contact switch km-2 opens, the relay protection circuit and signal circuit are disconnected, and the test switch switches from operating mode to test mode. When the normally open part disconnects from the normally open contact, that is, when the normally open contact switch km-1 returns to normally open and the normally closed contact switch km-2 returns to normally closed, the relay protection circuit and signal circuit remain disconnected, and the test switch remains in test mode. When the normally open part is driven again... When the normally open contact is touched and pressed, that is, when the normally open contact switch km-1 closes again and the normally closed contact switch km-2 opens again, the micro switch 4 is triggered again to switch states, thereby connecting the relay protection circuit and the signal circuit, and the test switch switches from test mode to working mode. When the normally open contact opens again, that is, when the normally open contact switch km-1 returns to normally open and the normally closed contact switch km-2 returns to normally closed, the relay protection circuit and the signal circuit remain closed, and the test switch remains in working mode.

[0032] In addition, refer to Figure 1 The housing 1 also includes a short-circuit circuit. This short-circuit circuit is used to stagger the conduction of the signal circuit and the relay protection circuit when they are disconnected. For example, the staggered conduction method for the short-circuit circuit with the signal circuit and the relay protection circuit is as follows: when the normally open contact is pressed down to below 0.3mm, the short-circuit circuit and the signal circuit are connected; simultaneously, when the normally open contact is pressed down, the normally closed contact rebounds, and when the normally closed contact rebounds to above 0.5mm, the relay protection circuit and the signal circuit are connected. The short-circuit action times of the signal circuit and the relay protection circuit are not synchronized. The contact that acts first is used to connect the current signal circuit / relay protection circuit with the short-circuit circuit to avoid damage to the equipment insulation caused by open-circuit high voltage and damage to other equipment.

[0033] Reference Figure 4 The housing 1 also includes a mounting base 5 connected to the top cover of the housing 1. A long, plate-shaped lifting seat 6 is provided on the side of the mounting base 5 facing the bottom cover. The lifting seat 6 is horizontally positioned and can be raised and lowered relative to the mounting base 5. A limiting platform 51 is also provided on the mounting base 5, extending along the length of the lifting seat 6. Both ends of the limiting platform 51 are provided with limiting guide rails 52 for horizontally limiting the lifting seat 6. The two ends of the lifting seat 6 are slidably connected to the limiting guide rails 52 in the vertical direction.

[0034] Reference Figure 5 , Figure 6 and Figure 7The lifting base 6 is provided with an operating fulcrum 62 for pressing down the normally open part of the switch spring 41. In this embodiment, four columns 61 are provided on the side of the lifting base 6 facing the micro switch 4, each column 61 corresponding to a set of micro switches 4. The operating fulcrum 62 is provided at the bottom end of the column 61 so that when the lifting base 6 descends, the operating fulcrum 62 can stably contact the normally open part of the switch spring 41.

[0035] Continue to refer to Figure 5 , Figure 6 and Figure 7 A support spring 7 is also provided between the lifting seat 6 and the micro switch 4 to support the lifting seat 6. The support spring 7 is sleeved on the column 61, with one end of the support spring 7 abutting against the lifting seat 6 and the other end abutting against the top surface of the micro switch 4. In this embodiment, there are four support springs 7, with one support spring 7 corresponding to each group of micro switches 4, and when the support spring 7 is in its natural state, the operating fulcrum 62 is separated from the switch spring 41. That is, assuming the current state of the test switch is the working mode, when the lifting seat 6 descends to the operating fulcrum 62 and presses down on the normally open part of the switch spring 41, squeezing the normally open contact downwards, the normally open contact switch km-1 closes, the normally closed contact switch km-2 opens, and the micro switch 4 disconnects the relay protection circuit and the signal circuit. During the disconnection, the signal circuit and the disconnected relay protection circuit are sequentially connected to the short-circuit circuit and then disconnected. When the force of the lifting seat 6 is released, the normally open contact springs back. This is the test mode. The operator can then insert the external test connector into the test hole 102 to form a complete test circuit between the external test circuit and the relay protection circuit. When the operating fulcrum 62 is driven again to press down on the switch spring 41, the normally open contact switch km-1 opens, the normally closed contact switch km-2 closes, and the micro switch 4 connects the relay protection circuit and the signal circuit. This is the working mode.

[0036] Continue to refer to Figure 5 , Figure 6 and Figure 7 The mounting base 5 is equipped with a mode switching mechanism for driving the lifting base 6 to rise and fall, so that the operating fulcrum 62 contacts / disconnects with the switch spring 41 of the micro switch 4. Specifically, the mode switching mechanism includes a groove 53 formed on the upper surface of the mounting base 5, a slider 54 slidably disposed in the groove 53, and a drive assembly for driving the slider 54 to slide horizontally within the groove 53. The groove 53 is formed along the width direction of the limiting platform 51, and the groove 53 has a sliding part 531 and a clearance part 532. The slider 54 is located in the sliding part 531, and the slider 54 can slide back and forth in the sliding part 531.

[0037] The bottom of the groove of the sliding part 531 has a through hole 55 penetrating the bottom of the mounting base 5, and the slider 54 has a through hole 541 that mates with the through hole 55. A cylinder 63 is provided on the top of the lifting base 6. The top of the cylinder 63 is spherical and extends into the sliding groove 53 through the through hole 55. When the support spring 7 is in its natural state, the spherical apex of the cylinder 63 is located within the through hole 541. A return spring 58 is provided in the clearance part 532. A guide post 543 is provided at one end of the slider 54 near the clearance part 532, and the slider 54 is fitted over the guide post 543. One end of the return spring 58 abuts against the slider 54, and the other end abuts against the groove wall of the clearance part 532 facing the sliding part 531. Figure 1 When the test switch is in working mode, when the slider 54 is pushed towards the relief part 532 and compresses the return spring 58, the bottom wall of the through hole 541 abuts against and presses the spherical apex of the top of the cylinder 63. The cylinder 63 is forced downward to press the lifting seat 6, which descends and presses the support spring 7 downward, causing the operating fulcrum 62 on the cylinder 61 to press the switch spring 41 of the micro switch 4, thereby disconnecting the relay protection circuit and the signal circuit. This is the test mode of the test switch. When the pushing force of the slider 54 is removed, the return spring 58 provides a restoring force to the slider 54, causing the slider 54 to slide away from the relief part 532. When the slider 54 slides to the point where the through hole 541 is opposite to the through hole 55, the support spring 7 provides an upward restoring force to the lifting seat 6, causing the lifting seat 6 to rise. This disconnects the operating fulcrum 62 from the switch spring 41 of the micro switch 4, and the test switch continues to maintain the test mode. When the slider 54 is driven to slide towards the relief part 532 again and compress the return spring 58, the bottom wall of the through hole 541 abuts against and presses the spherical apex of the top of the cylinder 63, causing the operating fulcrum 62 to press the switch spring 41 of the micro switch 4 again, thereby connecting the relay protection circuit and the signal circuit. At this time, the test switch switches to the working mode. When the thrust of the slider 54 is removed, the switch spring 41 resets, and the relay protection circuit and the signal circuit remain connected. At this time, the test switch continues to maintain the working mode.

[0038] In addition, to make the sliding of the hole wall of the through hole 541 smoother when it comes into contact with the spherical vertex of the cylinder 63, a chamfer or rounding treatment can be added to the hole wall of the through hole 541.

[0039] Reference Figure 5 , Figure 6 and Figure 7The upper surface of the mounting base 5 is also provided with a circular rotating groove 56, which communicates with the sliding part 531 of the slide groove 53. The driving assembly includes a turntable 57 rotatably disposed in the rotating groove 56 and a rotating component for driving the turntable 57 to rotate. A stop groove 571 is provided on the edge of the turntable 57, located at the communication between the rotating groove 56 and the slide groove 53. The stop groove 571 is W-shaped, and the groove wall of the stop groove 571 facing the slide groove 53 is wavy and smooth. A stop block 542 is provided at one end of the slider 54 near the rotating groove 56. The stop block 542 is inserted into the stop groove 571, and the end of the stop block 542 inserted into the stop groove 571 is arc-shaped and abuts against and slides against the wavy groove wall. The two end walls of the stop groove 571 and the two sides of the stop block 542 cooperate to form a limiting structure, thereby limiting the rotation angle of the turntable 57. The gear slot 571 is divided into a working gear slot 5711 and a test gear slot 5712. The working gear slot 5711 and the test gear slot 5712 correspond to the test mode and the working mode, respectively.

[0040] Combination Figure 1 Initially, the end of the stop block 542 is positioned in the working position slot 5711, and the operating fulcrum 62 on the column 61 is disconnected from the switch spring 41 of the micro switch 4. That is, the relay protection circuit and the signal circuit are connected, and the test switch is in working mode. When a rotational force is applied to the turntable 57 to rotate the test position slot 5712 towards the working position slot 5711, the wavy groove wall of the position slot 571 has an arc. The stop block 542 is forced to slide along the length of the slide groove 53 along the undulating path of the groove wall of the position slot 571 due to the abutment force of the wavy groove wall. The return spring 58 is compressed and generates a reverse force on the slider 54, so that the end of the stop block 542 always remains in contact with the groove wall of the position slot 571. During the sliding of the stop block 542, since the wavy groove wall of the stop slot 571 is uphill relative to the stop block 542 in the first half and downhill relative to the stop block 542 in the second half, the stop block 542 slides towards the clearance part 532 during the first half of the sliding. The bottom hole wall of the through hole 541 abuts against and presses the spherical apex of the top of the cylinder 63. The cylinder 63 is forced downward to press the lifting seat 6, causing the operating fulcrum 62 on the column 61 to press the switch spring 41 of the micro switch 4, thereby disconnecting the relay protection circuit and the signal circuit, and thus switching the test switch to the test mode. During the second half of the sliding, that is, when the turntable 57 rotates to the stop block 542 falling into the test stop slot 5712, the slider 54 loses the thrust of the stop block 542 and resets, and the lifting seat 6 resets, thereby disconnecting the operating fulcrum 62 from the switch spring 41 of the micro switch 4. At this time, the test switch continues to maintain the test mode. Conversely, rotating the turntable 57 in the opposite direction will cause the stop block 542 to fall into the working stop slot 5711, thus switching from the test mode to the working mode.

[0041] The mounting base 5 is also provided with a cover 59 for covering the slide groove 53 and the rotating groove 56, thereby limiting and protecting the structure inside the slide groove 53 and the rotating groove 56.

[0042] Combination Figure 4 and Figure 8 The rotating component includes a knob 8 rotatably mounted on the top cover of the housing 1. The knob 8 has a rotating shaft that passes vertically downward through the axis of the turntable 57 and is fixedly connected to the turntable 57. The protective cover 2 has a limiting groove 21 that matches the shape of the knob 8. When the test switch is in the working mode, the knob 8 is just placed in the limiting groove 21 after the protective cover 2 is closed, thereby limiting the knob 8 and preventing the knob 8 from rotating in the working mode.

[0043] The implementation principle of this embodiment is as follows: Initially, it is assumed that the test switch is in the working mode. When it is necessary to switch the test switch to the test mode, the knob 8 can be rotated to apply rotational force to the turntable 57, causing the test gear slot 5712 to rotate towards the working gear slot 5711. During the sliding of the stop block 542, the slider 54 is pushed to slide accordingly, thereby driving the lifting seat 6 to descend to the operating fulcrum 62 and contact the switch spring 41 of the micro switch 4, pressing down the normally open contact. When the test gear slot 5712 rotates to the correct position, the return spring 58 drives the slider 54 to slide, causing the stop block 542 to fall into place. The limiting structure formed by the side wall of the test gear slot 5712 and the stop block 542 restricts the rotation of the turntable 57. The stop block 542 remains inserted with the test gear slot 5712, thereby realizing the conversion from the working mode to the test mode. Conversely, when it is necessary to switch to the working mode, rotate the knob 8 in the opposite direction to make the stop block 542 fall into the working stop slot 5711, thus realizing the switch from the test mode to the working mode.

[0044] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A test switch, comprising a housing (1) and a relay protection circuit and a signal circuit disposed within the housing (1), characterized in that, The relay protection circuit and the signal circuit are electrically connected. A micro switch for controlling the on / off state between the relay protection circuit and the signal circuit is provided inside the housing. A test hole (102) is provided on the housing (1). A test connector electrically connected to the relay protection circuit is provided in the test hole (102). A mounting base (5) connected to the top cover of the housing (1) is provided inside the housing (1). A lifting seat (6) is provided on the side of the mounting base (5) facing the bottom of the housing (1). An operating fulcrum (62) for touching the switch spring (41) of the micro switch (4) is provided on the mounting base (5). A mode switching mechanism for driving the lifting seat (6) to rise and fall so that the operating fulcrum (62) contacts the switch spring (41) of the micro switch (4) and thus triggers the test switch to switch to test mode / working mode.

2. The test switch according to claim 1, characterized in that, The mounting base (5) is provided with a limiting platform (51), and the limiting platform (51) is provided with a limiting guide rail (52) that is slidably connected to the lifting base (6) up and down.

3. The test switch according to claim 1, characterized in that, A support spring (7) for supporting the lifting seat (6) is provided between the lifting seat (6) and the micro switch (4).

4. The test switch according to claim 3, characterized in that, The mode switching mechanism includes a groove (53) on the upper surface of the mounting base (5), a slider (54) slidably disposed in the groove (53), and a drive assembly for driving the slider (54) to slide horizontally in the groove (53). The bottom of the groove (53) is provided with a through hole (55) penetrating the bottom of the mounting base (5). A cylinder (63) is provided on the lifting base (6). The top of the cylinder (63) is spherical and extends into the groove (53) through the through hole (55). The slider (54) is provided with a through hole (541) that cooperates with the through hole (55). The spherical apex of the top of the cylinder (63) is located in the through hole (541).

5. The test switch according to claim 4, characterized in that, The driving assembly includes a turntable (57) rotatably mounted on the mounting base (5) and a rotating component for driving the turntable (57) to rotate. The upper surface of the mounting base (5) is also provided with a rotating groove (56) for accommodating the turntable (57), the rotating groove (56) communicating with a sliding groove (53). The edge of the turntable (57) is provided with a gear slot (571), which is divided into a test gear slot (5712) and a working gear slot (5711). 711) Corresponding to the test mode and the working mode respectively, the test gear slot (5712) and the working gear slot (5711) are arranged adjacent to each other, and the adjacent parts of the test gear slot (5712) and the working gear slot (5711) are rounded. The slider (54) is provided with a stop block (542) at one end near the rotating groove (56). The stop block (542) is inserted into the gear slot (571) and the end of the stop block (542) abuts and slides against the groove walls of the test gear slot (5712) and the working gear slot (5711).

6. The test switch according to claim 5, characterized in that, A reset spring (58) is also provided in the slide groove (53). One end of the reset spring (58) abuts against the end of the slider (54) away from the stop block (542), and the other end abuts against the groove wall of the slide groove (53) on the side facing the rotating groove (56).

7. The test switch according to claim 6, characterized in that, The rotating component includes a knob (8) that is rotatably mounted on the top cover of the housing (1). The knob (8) is provided with a rotating shaft that passes vertically downward through the axis of the turntable (57) and is fixedly connected to the turntable (57).

8. The test switch according to claim 7, characterized in that, The top of the housing (1) is provided with a protective cover (2) for covering the knob (8).

9. The test switch according to claim 1, characterized in that, The housing (1) is open at the bottom, and a base (3) is provided at the bottom of the housing (1). An elastic buckle (31) is provided on the base (3), and a buckle hole (101) is provided on the side wall of the housing (1) to engage with the elastic buckle (31).

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