Valve element piston and valve seat

Abstract

The valve element piston and valve seat comprises a connecting rod, a first piston, a second piston and a spring, the first piston is fixedly connected with the connecting rod through a first bolt, the second piston is fixedly connected with the connecting rod through a second bolt, a first blocking block is located at the end, facing the second piston, of the first piston, an annular groove is formed in one side wall of the piston, and a first sealing ring is installed in the annular groove. The second piston comprises a second blocking block, the second blocking block is located at the end, facing the first piston, of the second piston, a nut of the second bolt exceeds the lower end face of the second piston, a part of the spring is arranged on the nut in a sleeved mode, the shell comprises a first cavity, a second cavity and a channel, the first cavity and the second cavity are distributed up and down, and the channel is located between the first cavity and the second cavity. The bottom cover is installed at the opening end of the second cavity, the lower end of the spring abuts against the inner bottom face of the bottom cover, the first piston and the second piston can be connected with the connecting rod from the upper opening and the lower opening respectively, and the valve element piston and the valve seat shell are convenient and fast to install and convenient to replace.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic valves, in particular to a valve core piston and a valve seat. Background Art

[0002] In the prior art, pilot solenoid valves are generally used to control the opening or closing of large-flow media. The opening and closing of large-flow media are controlled by a smaller valve-opening electromagnetic force. The pilot solenoid valve has a structure of a large piston and a small piston arranged in the valve chamber. The valve needle of the solenoid valve first cooperates with the small piston to achieve a smaller solenoid valve starting force, and then the main valve port is started by the large piston to realize the opening or closing of the valve. The large piston of a general pilot solenoid valve is arranged in a valve seat, and the switching connection between the valve ports is realized by moving in the valve seat. However, the installation structure between the existing valve seat and the piston is complicated, and installation and disassembly are relatively troublesome. At the same time, due to the large medium flow in the valve body, the aging of the piston will be accelerated. The sealing assembly of the aged piston needs to be replaced frequently to ensure the sealing of the piston. Therefore, a technical solution is needed to solve the above problems. Utility Model Content

[0003] In view of the above technical requirements, the utility model provides a valve core piston and a valve seat.

[0004] The utility model provides a valve core piston and a valve seat, comprising a connecting rod, a piston 1, a piston 2 and a spring, wherein the piston 1 and the piston 2 are respectively fixedly installed at both ends of the connecting rod, the piston 1 is fixedly connected to the connecting rod by a bolt 1, and the piston 2 is fixedly connected to the connecting rod by a bolt 2, the piston 1 comprises a blocking block 1, the blocking block 1 is located at one end of the piston 1 facing the piston 2, an annular groove is provided on one side wall of the piston, a sealing ring 1 is installed in the annular groove, the piston 2 comprises a blocking block 2, the blocking block 2 is located at one end of the piston 2 facing the piston 1, the nut of the bolt 2 exceeds the lower end surface of the piston 2, and a part of the spring is sleeved on the outer periphery of the nut.

[0005] Furthermore, both piston one and piston two are equipped with blocks, and the blocks are fixedly connected to the connecting rod. The block in piston one clamps and fixes block one with piston one, and the block in piston two clamps and fixes block two with piston two.

[0006] Furthermore, the piston one is provided with a limiting groove one, the limiting groove one is located at the bottom of the piston one, the blocking block one is installed in the limiting groove one, and a part of the blocking block one is sunk into the limiting groove one, and the piston two is provided with a limiting groove two, the limiting groove two is located at the top of the piston two, the blocking block two is installed in the limiting groove two, and a part of the blocking block two is located in the limiting groove two.

[0007] Furthermore, the second piston includes a ring plate, which is located on the bottom surface of the second piston and extends downward, and a part of the spring is located within the range of the ring plate.

[0008] Furthermore, the connecting rod is provided with two shoulders, which are distributed along the length direction of the connecting rod, and there is a distance between the two shoulders. The upper shoulder can press against the lower end surface of the block located in piston one, and the lower shoulder can press against the upper end surface of the block located in piston two.

[0009] Furthermore, the piston 1 is provided with a slot 1, the piston 2 is provided with a slot 2, a portion of the upper end of the connecting rod is inserted into the slot 1, and a portion of the lower end of the connecting rod is inserted into the slot 2.

[0010] Furthermore, the stopper located in the piston one is embedded in the block one, and the lower end surface of the stopper located in the piston one is flush with the lower end surface of the block one; the stopper located in the piston two is embedded in the block two, and the upper end surface of the stopper located in the piston two is flush with the upper end surface of the block two.

[0011] Furthermore, the piston one is provided with a limit groove three, a part of the stopper located in the piston one is located in the limit groove three, the piston two is provided with a limit groove four, a part of the stopper located in the piston two is located in the limit groove four 4, the stopper is provided with a slot three, and the two ends of the connecting rod can be inserted into the slot three.

[0012] Furthermore, a valve seat includes a valve core piston, a shell and a bottom cover, the shell includes cavity one, cavity two and a channel, the cavity one and cavity two are distributed up and down, the channel is located between cavity one and cavity two, the channel connects cavity one and cavity two, the piston one is located in cavity one, the piston two is located in cavity two, the piston can move up and down to switch the channel to connect cavity one and cavity two, the bottom cover is installed at the opening end of cavity two, and the lower end of the spring presses against the inner bottom surface of the bottom cover.

[0013] Furthermore, it includes a second sealing ring, the bottom cover is provided with a guide groove, a part of the second piston is located in the guide groove, the second sealing ring is located on the inner wall of the guide groove or the outer wall of the second piston, the bottom surface of the guide groove is provided with a through hole, and the through hole is connected to the lower end surface of the bottom cover.

[0014] Compared with the related art, the valve core piston and valve seat provided by the utility model have the following beneficial effects:

[0015] 1. The utility model piston 1 and piston 2 can be fixed to the connecting rod by bolt 1 and bolt 2 respectively, the two shoulders arranged on the connecting rod limit the distance between piston 1 and piston 2, the block 1 and block 2 are in positions facing each other, so that the travel distance of the piston is shortest when moving and blocking, the cavity 1 and cavity 2 of the shell are distributed up and down and open upward and downward respectively, the connecting rod can pass through the channel 2 and the two ends are respectively located in the cavity 1 and cavity 2, the piston 1 and piston 2 can be connected to the connecting rod from the upper and lower openings respectively, the valve core piston and the valve seat shell are convenient and fast to install and easy to replace.

[0016] 2. When the piston 2 of the utility model moves in the cavity 2, it passes through the sealing ring 2 and the through hole in the center of the bottom cover, and the piston seals the inside of the cavity 2. The through hole can balance the air pressure in the space below the sealing ring 2, thereby reducing the impact of air pressure changes when the piston 2 moves, and making the movement of the valve core piston more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional view of the first embodiment.

[0018] Figure 2 It is a cross-sectional view of the second embodiment.

[0019] Figure 3 It is a cross-sectional view of embodiment 3.

[0020] Figure 4 It is a cross-sectional view of embodiment 4.

[0021] Numbers in the figure: 1. connecting rod; 11. shoulder; 12. block; 121. slot three; 2. piston one; 21. annular groove; 22. sealing ring one; 23. bolt one; 24. countersunk hole one; 25. limiting groove one; 26. slot one; 27. limiting groove three; 3. blocking block one; 4. piston two; 41. limiting groove two; 42. bolt two; 421. nut; 43. slot two; 44. ring plate; 45. limiting groove four; 5. blocking block two; 6. spring; 7. housing; 71. cavity one; 72. cavity two; 73. passage; 8. bottom cover; 81. guide groove; 811. sealing ring two; 82. through hole. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively with reference to the accompanying drawings. The accompanying drawings show typical embodiments of the present invention.

[0023] Embodiment 1:

[0024] like Figure 1As shown, this embodiment discloses a valve core piston, including a connecting rod 1, a piston 2, a piston 4 and a spring 6. The piston 2 and the piston 4 are fixedly installed at both ends of the connecting rod 1 respectively. The connecting rod 1 is provided with two blocking shoulders 11. The two blocking shoulders 11 are distributed along the length direction of the connecting rod 1. A distance is set between the two blocking shoulders 11. The two blocking shoulders 11 limit the installation position between the piston 2 and the piston 4, so that the piston 2 and the piston 4 maintain a certain distance. The piston 2 is fixedly connected to the connecting rod 1 by a bolt 23. The piston 2 includes a blocking block 3. The blocking block 3 is located at one end of the piston 2 facing the piston 4. The piston 2 is provided with a limiting groove 25. The limiting groove 25 is located at the bottom of the piston 2. The blocking block 3 is installed in the limiting groove 25. A part of the blocking block 3 sinks into the limiting groove 25. The positioning groove 25 limits the block 3 so that the block 3 can be inserted into the limiting groove 25 for installation. A part of the block 3 exceeds the limiting groove 25 and can be used to press the seal. The piston 2 and the piston 2 4 are both installed with the block 12. The block 12 located in the piston 2 presses the upper shoulder 11 and the block 3 respectively. The block 12 located in the piston 2 is embedded in the block 3. The lower end surface of the block 12 located in the piston 2 is flush with the lower end surface of the block 3. The block 12 can increase the pressing area of ​​the shoulder 11 on the block 3 and the block 2 5, and can better clamp the block 3 and the block 2 5. The bolt 23 passes through the piston 2 and the block 3 from the top of the piston 2 and is connected to the connecting rod 1 through a thread. The bolt 23 can press the piston 2 to clamp the block 3 and fix it.

[0025] like Figure 1 As shown, piston 24 includes block 25, block 25 is located at one end of piston 24 facing piston 12, piston 24 is provided with limit groove 241, limit groove 241 is located at the top of piston 24, block 25 is installed in limit groove 241, a part of block 25 is located in limit groove 241, block 12 located in piston 24 presses against lower shoulder 11 and block 25 respectively, block 12 can increase the pressing area of ​​shoulder 11 against block 13 and block 25, piston 24 is fixedly connected to connecting rod 1 by bolt 242, similarly, block 25 penetrates piston 24 and block 25 and is threadedly connected with connecting rod 1 by bolt 242, nut 421 of bolt 242 exceeds the lower end face of piston 24, a part of spring 6 is sleeved on the outer periphery of nut 421, spring 6 sleeved on the outer periphery of nut 421 can make spring 6 more stable when compressed.

[0026] like Figure 1 As shown, an annular groove 21 is provided on the side wall of the piston 2, and a sealing ring 22 is installed in the annular groove 21. The sealing ring 22 is used to divide the space for installing the piston 2 into two parts, and can push the piston 2 to move through the pressure of the medium.

[0027] like Figure 1 As shown, more preferably, piston 2 is provided with a countersunk hole 24, and bolt 23 is partially sunk into countersunk hole 24 to prevent bolt 23 from exceeding the top of piston 2 and interfering with the movement of piston 2.

[0028] like Figure 1 As shown, more preferably, piston 1 2 is provided with a slot 1 26, piston 2 4 is provided with a slot 2 43, a portion of the upper end of the connecting rod 1 is inserted into the slot 1 26, a portion of the lower end of the connecting rod 1 is inserted into the slot 2 43, and both ends of the connecting rod 1 can be inserted into a portion of piston 1 2 and piston 2 4, so that the connection between the connecting rod 1 and piston 1 2 and piston 2 4 is more firm and stable.

[0029] like Figure 1 As shown, more preferably, the stopper 12 located in the piston 12 is embedded in the block 13, and the lower end surface of the stopper 12 located in the piston 12 is flush with the lower end surface of the block 13, the stopper 12 located in the piston 24 is embedded in the block 25, and the upper end surface of the stopper 12 located in the piston 24 is flush with the upper end surface of the block 2 (5), so as to prevent the stopper 12 from interfering with the pressure seal of the block 13 and the block 25.

[0030] like Figure 1 As shown, piston 2 4 includes a ring plate 44, which is located on the bottom surface of piston 2 4 and extends downward, a portion of spring 6 is located within the range of ring plate 44, ring plate 44 and nut 421 can clamp spring 6, and an annular space formed by ring plate 44 and nut 421 for installing spring 6 is more stable when spring 6 is compressed.

[0031] Embodiment 2:

[0032] like Figure 2 As shown, this embodiment discloses a valve seat, including the valve core piston, shell 7 and bottom cover 8 in embodiment 1, shell 7 includes cavity 1 71, cavity 2 72 and channel 73, cavity 1 71 and cavity 2 72 are distributed up and down, channel 73 is located between cavity 1 71 and cavity 2 72, channel 73 connects cavity 1 71 and cavity 2 72, piston 1 2 is located in cavity 1 71, sealing ring 1 22 presses against the inner wall of sealing cavity 1 71, sealing ring 1 22 separates cavity 1 71 into upper and lower parts, the air pressure above sealing ring 1 22 increases so that piston 1 2 can move downward, so that block 1 3 blocks channel 73 and cavity 1 71.

[0033] The piston 24 is located in the cavity 272, and the bottom cover 8 is installed at the open end of the cavity 272. The bottom cover 8 is fixedly connected by threads and seals the cavity 272. The lower end of the spring 6 presses against the inner bottom surface of the bottom cover 8. When the air pressure in the upper part of the sealing ring 22 disappears, the spring 6 presses the piston 24 upward, so that the block 25 can block the channel 73 and the cavity 272. The piston 12 and the piston 24 can move up and down, so that the channel 73 switches to connect the cavity 171 and the cavity 272.

[0034] like Figure 2 As shown, since the space of cavity 2 72 is also increased, during the movement of piston 2 4, the air pressure in the upper and lower parts of piston 2 4 fluctuates. In order to prevent the air pressure in cavity 2 72 from affecting the valve core piston, the bottom cover 8 is provided with a guide groove 81, a part of piston 2 4 is located in the guide groove 81, and the sealing ring 2 811 is located on the inner side wall of the guide groove 81. A through hole 82 is provided on the bottom surface of the guide groove 81, and the through hole 82 is connected to the lower end surface of the bottom cover 8. When piston 2 4 moves in cavity 2 72, piston 2 4 seals the inside of cavity 2 72, and the through hole 82 can balance the air pressure in the space below the sealing ring 2 811, so that the influence of air pressure changes on piston 2 4 during movement is reduced, and the movement of the valve core piston is more stable.

[0035] The cavity 1 71 and the cavity 2 72 of the shell 7 of this embodiment are distributed up and down and open upward and downward respectively. The connecting rod 1 can pass through the channel 73 and its two ends are respectively located in the cavity 1 71 and the cavity 2 72. The piston 1 2 and the piston 2 4 can be connected to the connecting rod 1 from the upper and lower openings respectively. The valve core piston and the valve seat are easy to install and easy to replace.

[0036] Embodiment three:

[0037] like Figure 3As shown, the present embodiment discloses a valve core piston, which is suitable for the case where the valve body is larger and the diameter of the valve core piston is also larger, including a connecting rod 1, a piston 2, a piston 4 and a spring 6. The piston 2 and the piston 4 are fixedly installed at both ends of the connecting rod 1, respectively. The piston 2 and the piston 4 are both installed with a block 12, and the block 12 is fixedly connected to the connecting rod 1. The block 12 located in the piston 2 and the piston 2 clamps and fixes the block 3, and the block 12 located in the piston 4 and the piston 4 clamps and fixes the block 5. The installation position between the piston 2 and the piston 4 is limited so that the piston 2 and the piston 4 maintain a certain distance. The piston 2 is fixedly connected to the connecting rod 1 by a bolt 23. The piston 2 includes a block 3, and the block 3 is located at The piston 2 is facing one end of the piston 24, and the piston 2 is provided with a limiting groove 25, which is located at the bottom of the piston 2, and the block 3 is installed in the limiting groove 25, and a part of the block 3 sinks into the limiting groove 25. The limiting groove 25 limits the block 3 so that the block 3 can be inserted into the limiting groove 25 for installation, and a part of the block 3 exceeds the limiting groove 25 and can be used to press the seal. The block 12 can increase the pressing area of ​​the shoulder 11 on the block 3 and the block 25, and can better clamp the block 3 and the block 25. The bolt 23 passes through the piston 2 and the block 3 from the top of the piston 2 and is connected to the connecting rod 1 through a thread, and the bolt 23 can press the piston 2 to clamp the block 3 and fix it.

[0038] like Figure 3 As shown, two annular grooves 21 are provided on the side wall of the piston 2, and sealing rings 22 are installed in the two annular grooves 21. The sealing rings 22 are used to divide the space for installing the piston 2 into two parts, and can push the piston 2 to move by the pressure of the medium. The two annular grooves 21 can make the sealing and blocking effect better.

[0039] like Figure 3 As shown, piston 2 is provided with a countersunk hole 24, into which bolt 23 can be sunk, thereby preventing bolt 23 from exceeding the top of piston 2 and interfering with the movement of piston 2.

[0040] like Figure 3 As shown, more preferably, piston 12 is provided with a limiting groove 3 27, and a part of the stopper 12 located in piston 12 is located in the limiting groove 3 27; piston 2 4 is provided with a limiting groove 45, and a part of the stopper 12 located in piston 2 4 is located in the limiting groove 45, so that the stopper 12 can be more stably installed in piston 1 2 and piston 2 4 to play a limiting role. Compared with the stopper 12 in embodiment 1, the stopper 12 of this embodiment is larger in volume and can better press against the annular block 1 3 and block 2 5 with increased diameters, and better maintain the deformation degree of block 1 3 and block 2 5.

[0041] like Figure 3As shown, piston 24 includes block 25, block 25 is located at one end of piston 24 facing piston 1 2, piston 24 is provided with limit groove 241, limit groove 241 is located at the top of piston 24, block 25 is installed in limit groove 241, a part of block 25 is located in limit groove 241, block 12 located in piston 24 presses against lower shoulder 11 and block 25 respectively, block 12 can increase the pressing area of ​​shoulder 11 against block 1 3 and block 25, piston 24 is fixedly connected to connecting rod 1 by bolt 242, similarly block 25 penetrates piston 24 and block 25 through bolt 242 and is threadedly connected to connecting rod 1 to clamp and fix with shoulder 11.

[0042] like Figure 3 As shown, more preferably, piston 2 4 includes a ring plate 44, which is located on the bottom surface of piston 2 4 and extends downward, and a portion of spring 6 is located within the range of ring plate 44. The inner wall of ring plate 44 presses against the outer wall of spring 6 to provide limiting support for spring 6. The annular space formed by ring plate 44 prevents spring 6 from twisting during compression, thereby making the compression of spring 6 more stable.

[0043] like Figure 3 As shown, more preferably, the block 12 is provided with a slot three 121, and both ends of the connecting rod 1 can be inserted into the slot three 121. Both ends of the connecting rod 1 can be inserted into a part of the slot three 121 of the two block 12 to make the connection between the connecting rod 1 and the two block 12 more firmly and stably.

[0044] Embodiment 4:

[0045] like Figure 4 As shown, this embodiment discloses a valve body on the basis of the third embodiment, which is suitable for the situation that the valve body is larger, and the diameters of the cavity 1 71 and the cavity 2 72 in the shell 7 and the valve core piston are also enlarged. As the diameter of the piston 1 2 gradually increases, the diameters of the block 1 3 and the block 2 5 also increase accordingly. The double-layer sealing ring 1 22 in the piston 1 2 can achieve a better sealing and blocking effect, and can prevent the block 1 3 and the block 2 5 from loosening and causing leakage of the medium. The difference between this embodiment and the second embodiment is that the sealing ring 2 811 in this embodiment is located on the outer wall of the ring plate 44, and also plays the role of sealing between the contact surface of the ring plate 44 and the guide groove 81.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A valve core piston, characterized in that: The invention comprises a connecting rod (1), a piston 1 (2), a piston 2 (4) and a spring (6), wherein the two ends of the connecting rod (1) are respectively fixedly mounted with the piston 1 (2) and the piston 2 (4), wherein the piston 1 (2) is fixedly connected to the connecting rod (1) by means of a bolt 1 (23), and the piston 2 (4) is fixedly connected to the connecting rod (1) by means of a bolt 2 (42), wherein the piston 1 (2) comprises a block 1 (3), wherein the block 1 (3) is located at one end of the piston 1 (2) facing the piston 2 (4), an annular groove (21) is provided on the side wall of the piston 1 (2), and a sealing ring 1 (22) is installed in the annular groove (21), wherein the piston 2 (4) comprises a block 2 (5), wherein the block 2 (5) is located at one end of the piston 2 (4) facing the piston 1 (2), a nut (421) of the bolt 2 (42) exceeds the lower end surface of the piston 2 (4), and a part of the spring (6) is sleeved on the outer periphery of the nut (421).

2. A valve core piston according to claim 1, characterized in that: The piston one (2) and the piston two (4) are both equipped with a stopper (12), and the stopper (12) is fixedly connected to the connecting rod (1); the stopper (12) in the piston one (2) and the piston one (2) clamp and fix the stopper one (3); the stopper (12) in the piston two (4) and the piston two (4) clamp and fix the stopper two (5).

3. The valve core piston according to claim 1, characterized in that: The piston 1 (2) is provided with a limiting groove 1 (25), the limiting groove 1 (25) is located at the bottom of the piston 1 (2), the blocking block 1 (3) is installed in the limiting groove 1 (25), a part of the blocking block 1 (3) is sunk into the limiting groove 1 (25), the piston 2 (4) is provided with a limiting groove 2 (41), the limiting groove 2 (41) is located at the top of the piston 2 (4), the blocking block 2 (5) is installed in the limiting groove 2 (41), a part of the blocking block 2 (5) is located in the limiting groove 2 (41).

4. The valve core piston according to claim 1, characterized in that: The second piston (4) comprises a ring plate (44), the ring plate (44) is located on the bottom surface of the second piston (4) and extends downward, and a part of the spring (6) is located within the range of the ring plate (44).

5. The valve core piston according to claim 2, characterized in that: The connecting rod (1) is provided with two stop shoulders (11), the two stop shoulders (11) are distributed along the length direction of the connecting rod (1), and a distance is provided between the two stop shoulders (11). The stop shoulder (11) located at the upper part can press against the lower end surface of the stop block (12) located in the piston one (2), and the stop shoulder (11) located at the lower part can press against the upper end surface of the stop block (12) located in the piston two (4).

6. A valve core piston according to claim 5, characterized in that: The piston one (2) is provided with a slot one (26), the piston two (4) is provided with a slot two (43), a portion of the upper end of the connecting rod (1) is inserted into the slot one (26), and a portion of the lower end of the connecting rod (1) is inserted into the slot two (43).

7. The valve core piston according to claim 5, characterized in that: The stopper (12) located in the piston one (2) is embedded in the block one (3), and the lower end surface of the stopper (12) located in the piston one (2) is flush with the lower end surface of the block one (3); the stopper (12) located in the piston two (4) is embedded in the block two (5), and the upper end surface of the stopper (12) located in the piston two (4) is flush with the upper end surface of the block two (5).

8. The valve core piston according to claim 2, characterized in that: The piston one (2) is provided with a limiting groove three (27), a part of the stopper (12) located in the piston one (2) is located in the limiting groove three (27), the piston two (4) is provided with a limiting groove four (45), a part of the stopper (12) located in the piston two (4) is located in the limiting groove four (45), the stopper (12) is provided with a slot three (121), and both ends of the connecting rod (1) can be inserted into the slot three (121).

9. A valve seat, characterized in that: The invention comprises a valve core piston, a housing (7) and a bottom cover (8) as claimed in any one of claims 1 to 8, wherein the housing (7) comprises a cavity one (71), a cavity two (72) and a channel (73), wherein the cavity one (71) and the cavity two (72) are distributed up and down, and the channel (73) is located between the cavity one (71) and the cavity two (72), and the channel (73) connects the cavity one (71) and the cavity two (72), the piston one (2) is located in the cavity one (71), and the piston two (4) is located in the cavity two (72), the piston one (2) and the piston two (4) can move up and down so that the channel (73) switches to connect the cavity one (71) and the cavity two (72), and the bottom cover (8) is installed at the opening end of the cavity two (72), and the lower end of the spring (6) presses against the inner bottom surface of the bottom cover (8).

10. A valve seat according to claim 9, characterized in that: The invention comprises a second sealing ring (811), the bottom cover (8) is provided with a guide groove (81), a part of the second piston (4) is located in the guide groove (81), the second sealing ring (811) is located on the inner side wall of the guide groove (81) or the outer side wall of the second piston (4), the inner bottom surface of the guide groove (81) is provided with a through hole (82), and the through hole (82) is connected to the lower end surface of the bottom cover (8).

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