CN113838696A

CN113838696A - Push type switch

Info

Publication number: CN113838696A
Application number: CN202111175358.4A
Authority: CN
Inventors: 江杰洪; 高秀晶; 杨辉宝; 肖波; 李邦帅
Original assignee: Xiamen University of Technology
Current assignee: Xiamen University of Technology
Priority date: 2021-10-09
Filing date: 2021-10-09
Publication date: 2021-12-24
Anticipated expiration: 2041-10-09
Also published as: CN113838696B

Abstract

The invention discloses a push type switch, which comprises a shell and a push component arranged in the shell, wherein the push component comprises an on position and an off position, the shell comprises a first connecting part, a flange part and a second connecting part which are sequentially arranged along the axial direction, the end part of the first connecting part is provided with a waterproof rubber head and a first end cover sleeved outside the waterproof rubber head, the first end cover is connected to the first connecting part and tightly presses and fixes the waterproof rubber head, and one surface of the flange part facing to the second connecting part is provided with a first waterproof rubber ring; the invention is provided with a shell, a waterproof rubber head is fixedly connected with a first connecting part of the shell, a first waterproof rubber ring is also arranged on a flange part, the waterproof rubber head and the first waterproof rubber ring are used for realizing the waterproofing of a press type switch under the combined action, and the water can be prevented from entering the interior of the press type switch or entering equipment through the press type switch.

Description

Push type switch

Technical Field

The invention relates to the technical field of switches, in particular to a push type switch.

Background

With the demand of underwater resource detection and development, the application of underwater equipment is gradually increased, the main work content of the underwater equipment is navigation, positioning, sampling, measurement and the like, and the underwater equipment needs to use a power switch to control related equipment. At present, a waterproof switch used by underwater equipment is single in structure, and a spiral propelling structure is adopted to realize the connection of a power supply. The switch operation is complicated, the switch-on state is unclear, and a virtual connection state is easy to occur in the use process, so that the condition of poor power supply contact is caused. The operation process of switching on and off of the switch is carried out by applying a spiral rotary propulsion mode, so that thread abrasion is easily caused, the waterproof performance of the switch is reduced, and the service life of the switch is influenced. In the running process of the equipment, the power supply of the power supply is easily disconnected, so that the condition that the underwater equipment is out of control or lost is caused.

There are other forms of push switch in the prior art, but either can not play good waterproof effect, or do not apply to the field of circuit break-make, for example: chinese patent application publication No. CN104134563A discloses a push switch, which comprises an elastic element, a housing unit, an electrical connection unit, and a movable mechanism; the housing unit comprises a housing body, wherein the housing body is provided with an inner surrounding wall surface which defines a channel around an axis, and at least one guide post which protrudes from the inner surrounding wall surface towards the axis; the movable mechanism comprises a rotary seat penetrating through the channel and an electric contact part linked by the rotary seat, the rotary seat is provided with a plurality of driving surfaces which are parallel around the axis and extend obliquely, when the movable mechanism moves from an upper limit position to a lower limit position, one of the driving surfaces of the rotary seat is constantly made to abut against the guide post to slide so as to drive the electric contact part to change to a contact position or a disconnection position relative to the electric connection unit.

The Chinese patent with the granted bulletin number of CN209511159U discloses a press switch valve core, which comprises an upper shell, a lower shell and a press rod, a rotating shaft and a spring, wherein the upper shell is internally provided with the press rod, the rotating shaft and the spring; this proposal realizes on-off control of the water inlet/outlet by a pressing operation, but does not describe how to prevent water on the upper part of the pressing lever, and is not a switch for on-off control of the circuit.

Disclosure of Invention

The invention aims to provide a press switch to solve the problems in the prior art, and the press switch is provided with a shell, a waterproof rubber head is fixedly connected to a first connecting part of the shell, a first waterproof rubber ring is further arranged on a flange part, the press switch is waterproof under the combined action of the waterproof rubber head and the first waterproof rubber ring, and water can be prevented from entering the press switch or entering equipment through the press switch.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a push type switch which comprises a shell and a push component arranged in the shell, wherein the push component comprises an on position and an off position, the shell comprises a first connecting part, a flange part and a second connecting part which are sequentially arranged along the axial direction, the end part of the first connecting part is provided with a waterproof rubber head and a first end cover sleeved outside the waterproof rubber head, the first end cover is connected to the first connecting part and tightly presses and fixes the waterproof rubber head, and one surface of the flange part facing to the second connecting part is provided with a first waterproof rubber ring.

Preferably, a fastening nut is connected to the second connecting portion, and a second waterproof rubber ring is arranged on one surface of the fastening nut facing the flange portion.

Preferably, grooves for accommodating the first waterproof rubber ring and the second waterproof rubber ring are respectively arranged on the flange portion and the fastening nut.

Preferably, the pressing assembly comprises a pressing cap, a rotating shaft, a spring sleeved on the outer diameter side of the rotating shaft and a limiting portion fixed on the inner diameter side of the housing, the pressing cap can push the rotating shaft to move axially so as to clamp the rotating shaft into a high position and a low position of the limiting portion, and the high position and the low position correspond to an off position and an on position of the pressing assembly respectively.

Preferably, the outer diameter side of the rotating shaft is provided with a stop pin, the limiting part comprises a stop tooth matched with the stop pin, guide grooves with different radial depths are formed in the adjacent stop teeth, the deeper guide groove is used for enabling the rotating shaft to be in a high position through the stop pin, and the shallower guide groove is used for limiting the stop pin and enabling the stop pin to be clamped on the stop tooth, so that the rotating shaft can be in a low position.

Preferably, a guide block movable along the guide groove is provided on an outer diameter side of the pressing cap.

Preferably, the end face of the pressing cap is provided with a first wedge-shaped surface, the stop pin is provided with a second wedge-shaped surface engaged with the first wedge-shaped surface, and the first wedge-shaped surface can push the second wedge-shaped surface to drive the rotating shaft to rotate during axial movement.

Preferably, a second end cap is arranged on the inner diameter side of the second connecting part, and the spring abuts against the second end cap.

Preferably, the second end cover is provided with a contact mounting part, the contact mounting part is used for mounting a contact, and the contact can be in contact with the rotating shaft to realize communication.

Preferably, the contact mounting portion includes a first through hole radially provided in the second end cap and a second through hole axially provided in the second end cap, the first through hole communicating with the second through hole.

Compared with the prior art, the invention has the following technical effects:

(1) the invention is provided with a shell, a waterproof rubber head is fixedly connected with a first connecting part of the shell, a first waterproof rubber ring is also arranged on a flange part, the waterproof rubber head and the first waterproof rubber ring are utilized to realize the waterproofing of a press type switch under the combined action, and water can be prevented from entering the press type switch or entering equipment through the press type switch;

(2) according to the invention, the fastening nut is connected to the second connecting part, and the second waterproof rubber ring is arranged on one surface of the fastening nut facing the flange part, so that the fastening nut and the flange part can be clamped into working positions of a press switch fixed on a shell of equipment and the like together to fix the press switch, and double-sided sealing is realized by the first waterproof rubber ring and the second waterproof rubber ring together to prevent water from entering the equipment;

(3) the invention uses the way of pressing the waterproof rubber head to push the rotating shaft to touch the wire in the contact mounting part, and realizes the conduction of the circuit, the method adopts the matching of the stop pin in the rotating shaft and the stop tooth in the shell to determine the stroke of the rotating center, thereby avoiding the error in the manual judgment process, ensuring the good contact of the contact, and simultaneously reducing the problem of thread abrasion in the traditional switch which uses screw propulsion;

(4) the contact mounting part is provided with the radial first through hole and the axial second through hole which are matched to realize the mounting and fixing of the contact, so that the contact can be ensured to penetrate into the inner diameter side of the second end cover to be in contact communication with the rotating shaft, and the effective connection and disconnection of the push switch are further realized.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic view of a pressing cap according to the present invention;

FIG. 3 is a schematic view of a rotating shaft according to the present invention;

FIG. 4 is a schematic view of a partial cross-sectional view of the housing of the present invention;

FIG. 5 is a schematic view of a second end cap according to the present invention;

FIG. 6 is a cross-sectional view of the overall construction of the present invention;

wherein, 1, waterproof rubber head; 2. a first end cap; 3. a housing; 31. a first connection portion; 32. a flange portion; 33. a second connecting portion; 34. stopping teeth; 341. a third wedge face; 35. a first guide groove; 36. a second guide groove; 4. a first waterproof rubber ring; 5. fastening a nut; 6. pressing the cap; 61. a guide block; 62. a first wedge-shaped face; 7. a rotating shaft; 71. a stop pin; 711. a second wedge-shaped face; 8. a spring; 9. a second end cap; 91. a first through hole; 92. a second through hole; 10. a contact mounting portion; 11. and a second waterproof rubber ring.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a press switch to solve the problems in the prior art, the press switch is provided with a shell, a waterproof rubber head is fixedly connected to a first connecting part of the shell, a first waterproof rubber ring is further arranged on a flange part, the press switch is prevented from being waterproof by utilizing the combined action of the waterproof rubber head and the first waterproof rubber ring, and water can be prevented from entering the press switch or entering equipment through the press switch.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

As shown in fig. 1, 4 and 6, the present invention provides a push switch, which includes a housing 3 and a push component disposed in the housing 3, wherein the housing 3 is an external protection and bearing structure of the push switch, and can be installed on a working position such as a housing of an apparatus; the pressing member may be of an existing pressing type structure, for example, a leaf spring type resettable structure or a button type, and the pressing member includes an on position and an off position, that is, the purpose of turning on and off the power (or signal) can be achieved by the action of the pressing member, for example, a contact is provided on the housing 3, and the contact is turned on or off by pressing the pressing member. The shell 3 comprises a first connecting part 31, a flange part 32 and a second connecting part 33 which are sequentially arranged along the axial direction, the flange part 32 protrudes along the radial direction to divide the first connecting part 31 and the second connecting part 33 at two sides of the flange part 32, the cross section of the whole shell 3 is in a cross shape, and two ends of the whole shell are provided with communicated openings, so that the installation and the pressing operation of the pressing assembly are convenient; the first connecting portion 31 and the second connecting portion 33 may be connected to the first end cap 2 and the device (working surface) by means of external threads, or may be connected by a crimping buckle or the like. The end of the first connecting part 31 is provided with a waterproof rubber head 1 and a first end cover 2 sleeved outside the waterproof rubber head 1, the waterproof rubber head 1 is arranged on the end surface of the shell 3 and seals the middle opening of the shell 3, the first end cover 2 is connected on the first connecting part 31 and tightly presses and fixes the waterproof rubber head 1, so that the end face of the shell 3 is sealed and isolated from the outside by the waterproof rubber head 1, the other end face is arranged in the equipment shell (or the inner side of the working face), the sealing is performed by the first waterproof rubber ring 4, specifically, the first waterproof rubber ring 4 is provided on the surface of the flange portion 32 facing the second connecting portion 33, when the push switch is installed, the surface, provided with the first waterproof rubber ring 4, of the flange portion 32 is attached and fixed to a working surface such as an equipment housing, and the first waterproof rubber ring 4 is extruded and deformed to seal a gap between the flange portion 32 and the equipment housing and the like to realize waterproofness. According to the invention, the shell 3 is arranged, the waterproof rubber head 1 is fixedly connected with the first connecting part 31 of the shell 3, the first waterproof rubber ring 4 is also arranged on the flange part 32 of the shell 3, the waterproof rubber head 1 and the first waterproof rubber ring 4 are used for realizing the waterproof effect on the press switch under the combined action, and water can be prevented from entering the press switch or entering the equipment through the press switch.

As shown in fig. 1 and 6, the fastening nut 5 is connected to the second connecting portion 33 of the housing 3, if the second connecting portion 33 is provided with an external thread, the second connecting portion 33 can be directly connected to an opening on a working surface of a device or the like, and can be connected to the second connecting portion 33 by the fastening nut 5 through a thread structure, and the position of the second connecting portion 33 can be adjusted by rotating the fastening nut 5, that is, the distance between the fastening nut 5 and the flange portion 32 can be adjusted by rotating the fastening nut 5, so that the working surface of the housing or the like can be clamped and fixed between the fastening nut 5 and the flange portion 32, and since the surface of the fastening nut 5 facing the flange portion 32 is further provided with the second waterproof rubber ring 11, effective waterproofing of a portion where the push switch is installed can be realized by the first waterproof rubber ring 4 and the second waterproof rubber ring 11 provided on the flange portion 32, avoiding water from entering the interior of the device.

As shown in fig. 6, the flange portion 32 of the housing 3 and the fastening nut 5 are respectively provided with a groove for accommodating the first waterproof rubber ring 4 and the second waterproof rubber ring 11, it should be noted that the depth of the groove should be smaller than the diameters of the first waterproof rubber ring 4 and the second waterproof rubber ring 11, the groove can be exposed in a range of about half of the first waterproof rubber ring 4 and the second waterproof rubber ring 11, the position of the first waterproof rubber ring 4 and the position of the second waterproof rubber ring 11 can be fixed and the deformation state thereof can be limited by the groove, and it is avoided that the first waterproof rubber ring 4 and the second waterproof rubber ring 11 are distorted and deformed to affect the sealing and waterproof effect due to the rotation and friction and other factors when the fastening nut 5 is rotated.

As shown in fig. 1 and fig. 6 in combination with fig. 2 to 5, the pressing assembly includes a pressing cap 6, a rotating shaft 7, a spring 8 sleeved on the outer diameter side of the rotating shaft 7, and a limiting portion fixed on the inner diameter side of the housing 3, the pressing cap 6 can push the rotating shaft 7 to move axially, so that the rotating shaft 7 can be clamped into the high position and the low position of the limiting portion, the spring 8 is used to push the rotating shaft 7 to reset, the limiting portion can be limited by an elastic clamping portion respectively arranged at the high position and the low position, a protrusion is arranged on the rotating shaft 7, the high position and the low position of the rotating shaft 7 can be controlled by clamping the protrusion into the elastic clamping portion, or other button type structures in the prior art can be adopted, it should be noted that the high position and the low position respectively correspond to the off position and the on position of the pressing assembly, that is, the purpose of turning off and on is realized by the position movement of the rotating shaft 7, in this case, the rotary shaft 7 may be used as a conductor to communicate with the contact directly, or may be used as an intermediate structure for pushing another conductor to communicate with the contact.

As shown in fig. 1 and 6 in combination with fig. 3 to 5, a stop pin 71 is disposed on the outer diameter side of the rotating shaft 7, and the stop pin 71 protrudes outward in the radial direction of the rotating shaft 7 by a length between the first guide groove 35 and the second guide groove 36. In addition, the number of the stop pins 71 is corresponding to the number of the first guide grooves 35 and the number of the second guide grooves 36, respectively, and the positions of the first guide grooves 35 and the second guide grooves 36 can be corresponding to the positions of the stop pins 71 by rotating, for example, when the number of the stop pins 71 is 4, the number of the first guide grooves 35 and the number of the second guide grooves 36 are 4 and are arranged at intervals, of course, the number can be 2, 3 or 5, respectively, and the like. The limiting part of the shell 3 comprises a stopping tooth 34 matched with a stopping pin 71, guide grooves with different radial depths are arranged on adjacent stopping teeth 34, the guide grooves are divided into a deeper first guide groove 35 and a shallower second guide groove 36 according to the different radial depths, wherein the first guide groove 35 is used for passing through the stopping pin 71, namely, the axial position of the rotating shaft 7 is not limited, so that the rotating shaft 7 can be in a high position, the second guide groove 36 cannot pass through the stopping pin 71 and is used for limiting the stopping pin 71 and enabling the stopping pin 71 to be clamped on the stopping tooth 34, and therefore the rotating shaft 7 can be in a low position. It should be noted that the axial movement distance of the rotating shaft 7 (the axial distance between the upper position and the lower position) should be determined by considering the positions of the contacts, so as to ensure that the contacts can be well contacted and connected between the contacts or between the contacts and the rotating shaft 7 at the lower position, and can be smoothly disconnected at the upper position.

As shown in fig. 2, the outer diameter side of the pressing cap 6 is provided with the guide blocks 61 capable of moving along the first guide groove 35 and/or the second guide groove 36, actually, only 1 guide block 61 on the pressing cap 6 may be provided, and only one of the first guide groove 35 or the second guide groove 36 needs to be correspondingly guided to realize the axial movement of the pressing cap 6; of course, a plurality of guide blocks 61 may be provided, or the number of guide blocks may be the same as the total number of the first guide grooves 35 and the second guide grooves 36, so that the guide strength of the push cap 6 can be increased, the force bearing requirement for a single guide block 61 can be reduced, the abrasion can be reduced, and the service life of the push switch can be prolonged.

As shown in fig. 1 and fig. 2 to 4, the end surface of the pressing cap 6 is provided with a first wedge surface 62, the stop pin 71 of the rotating shaft 7 is provided with a second wedge surface 711 engaged with the first wedge surface 62, the first wedge surface 62 can push the second wedge surface 711 to drive the rotating shaft 7 to move axially when moving axially, when the tip of the second wedge surface 711 contacts with the tip of the third wedge surface 341, at this time, the second wedge surface 711 slides to and moves along the third wedge surface 341 under the elastic force of the spring 8, and further drives the rotating shaft 7 to rotate, so that the stop pin 71 provided on the rotating shaft 7 can be rotated to the position of the first guide groove 35 or the second guide groove 36, and further the axial position of the rotating shaft 7 can be changed and limited.

As shown in fig. 1 and 6, the second end cap 9 is provided on the inner diameter side of the second connecting portion 33 of the housing 3, the second end cap 9 may be provided with an external thread, and an internal thread is provided in the second connecting portion 33, so that the second end cap 9 can be screwed into the second connecting portion 33, and the spring 8 provided in the housing 3 may abut on the second end cap 9.

As shown in fig. 6, the second end cap 9 is provided with a contact mounting portion 10, the contact mounting portion 10 is used for mounting a contact, and the structure of the contact mounting portion 10 is provided according to the structural shape of the contact, for example, the contact mounting portion 10 may include a mounting hole or a mounting boss, the contact may be a metal spring sheet having a certain deformability, and the contact can maintain a contact state after the contact is contacted with the rotating shaft 7 to achieve contact connection, and the rotating shaft 7 may be made of a metal material and can communicate the contact as a conductor.

As shown in fig. 5 to 6, the contact mounting portion 10 includes a first through hole 91 radially disposed on the second end cap 9 and a second through hole 92 axially disposed on the second end cap 9, the first through hole 91 communicates with the second through hole 92, when mounting the contacts, the two contacts may be disposed in the two first through holes 91 in opposite directions, respectively, and then a locking device (e.g., a screw, a pin, etc.) is disposed in the second through hole 92 to fix the contacts in the first through holes 91.

The working process of the invention is as follows:

installing a push switch:

a) according to the work demand of push type switch, rotatory fastening nut 5 is taken out, lays the push type switch in required working face, installs fastening nut 5 once more and presss from both sides tightly in the working face, realizes holistic waterproof sealing effect.

b) The contact mounting portion 10 is connected with a required contact (wire), when the push switch is not switched on, the stop pin 71 of the rotating shaft 7 is positioned at the high position of the stop tooth 34 of the shell 3, the whole position of the rotating shaft 7 is upward higher, and the bottom of the rotating shaft 7 is not connected with the wire of the contact mounting portion 10.

When the push switch is opened:

c) according to the waterproof rubber head 1, the waterproof rubber head 1 transmits force to the pressing cap 6 inside, the pressing cap 6 pushes the rotating shaft 7 to move downwards (in the axial direction) relative to the shell 3, and under the action of the guide block 61, the pressing cap 6 can only do axial linear motion and cannot rotate.

d) When the pressing cap 6 pushes the rotating shaft 7 to move downwards, the lower end of the spring 8 is pressed by the second end cover 9, and the upper end is compressed by the stop pin 71 of the rotating shaft 7 to store force.

e) In the process that the pressing cap 6 pushes the rotating shaft 7 to move downwards, due to the upward pushing force of the spring 8, the second wedge-shaped surface 711 of the stop pin 71 of the rotating shaft 7 moves along the third wedge-shaped surface 341 of the stop tooth 34 of the housing 3, the rotating shaft 7 rotates, when the stop pin 71 is clamped into the second guide groove 36 of the stop tooth 34, the rotation is stopped, at this time, the rotating shaft 7 is in a low position, the rotating shaft 7 touches the conducting wire in the contact mounting part 10, and the switch is turned on.

When the push switch is turned off:

f) the waterproof rubber head 1 is pressed, the waterproof rubber head 1 transmits force to the pressing cap 6 inside, and the pressing cap 6 pushes the rotation shafts and 7 to move downward (axial direction) relative to the housing 3.

g) During the downward movement of the pressing cap 6 pushing the rotating shaft 7, the stop pin 71 of the rotating shaft 7 rotates around the rotating shaft 7 at the center, when the stop pin 71 is clamped into the first guide groove 35 of the stop tooth 34, the rotation is stopped and the initial state is restored under the action of the spring 8, at this time, the rotating shaft 7 is in the high position, and the rotating shaft 7 is disconnected from the conducting wire in the contact mounting part 10.

The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims

1. A push switch, characterized in that: including shell and setting be in pressing the subassembly in the shell, press the subassembly including switch-on position and open position, the shell includes first connecting portion, flange portion and the second connecting portion that set up in order along the axial, the tip of first connecting portion is provided with waterproof rubber head and cover and establishes the outside first end cover of waterproof rubber head, first end cover is connected on the first connecting portion and compress tightly fixedly waterproof rubber head, flange portion towards the one side of second connecting portion is provided with first waterproof rubber circle.

2. The push switch of claim 1 wherein: and a fastening nut is connected to the second connecting part, and a second waterproof rubber ring is arranged on one surface of the fastening nut facing the flange part.

3. The push switch of claim 2 wherein: the flange portion and the fastening nut are respectively provided with a groove for accommodating the first waterproof rubber ring and the second waterproof rubber ring.

4. The push switch of any of claims 1-3, wherein: the pressing assembly comprises a pressing cap, a rotating shaft, a spring and a limiting portion, wherein the spring is sleeved on the outer diameter side of the rotating shaft, the limiting portion is fixed on the inner diameter side of the shell, the pressing cap pushes the rotating shaft to move axially, the rotating shaft can be clamped into the high position and the low position of the limiting portion, and the high position and the low position correspond to an on position and an off position of the pressing assembly respectively.

5. The push switch of claim 4 wherein: the outer diameter side of the rotating shaft is provided with a stop pin, the limiting part comprises a stop tooth matched with the stop pin, the stop tooth is provided with guide grooves with different radial depths, the guide grooves are deep, the guide grooves are used for allowing the stop pin to pass through, the rotating shaft can be positioned at a high position, and the guide grooves are shallow and used for limiting the stop pin and enabling the stop pin to be clamped on the stop tooth, so that the rotating shaft can be positioned at a low position.

6. The push switch of claim 5 wherein: the outer diameter side of the pressing cap is provided with a guide block capable of moving along the guide groove.

7. The push switch of claim 6 wherein: the terminal surface of pressing the cap is provided with first wedge face, the stopper round pin be provided with the second wedge face of first wedge face meshing, can promote during first wedge face axial displacement the second wedge face drives the rotation axis rotates.

8. The push switch of claim 7 wherein: the inner diameter side of the second connecting part is provided with a second end cover, and the spring is abutted to the second end cover.

9. The push switch of claim 8 wherein: the second end cover is provided with a contact mounting part, the contact mounting part is used for mounting a contact, and the contact can be communicated with the rotating shaft in a contact mode.

10. The push switch of claim 9 wherein: the contact mounting part comprises a first through hole and a second through hole, the first through hole is radially arranged on the second end cover, the second through hole is axially arranged on the second end cover, and the first through hole is communicated with the second through hole.