CN116518099A

CN116518099A - Gate valve

Info

Publication number: CN116518099A
Application number: CN202210064130.6A
Authority: CN
Inventors: 郭卫强; 廖春玲; 朱东峰; 翁鹏斌
Original assignee: Kunshan Kinglai Hygienic Materials Co Ltd
Current assignee: Kunshan Kinglai Hygienic Materials Co Ltd
Priority date: 2022-01-20
Filing date: 2022-01-20
Publication date: 2023-08-01

Abstract

The invention belongs to the technical field of valves, and discloses a gate valve, which comprises: the valve body is provided with a flow channel cavity and a control cavity, the flow channel cavity extends along the X-axis direction, and the control cavity extends along the Z-axis direction; the two valve plates are used for opening and closing the flow channel cavity, are opposite to each other along the X-axis direction and are close to each other; the pneumatic device stretches into the valve body and drives the two valve plates to reciprocate between a first position for closing the flow channel cavity and a second position for opening the flow channel cavity; and the ball body is clamped between each valve plate and the pneumatic device and can roll along the Z-axis direction, and when the valve plates are in the first position and the second position, the valve plates, the pneumatic device and the ball body are mutually locked. The two valve plates enable the ball body to be clamped between the valve plates and the pneumatic device, the pneumatic device drives the valve plates to roll relative to the valve plates and the pneumatic device in the process of opening and closing the flow channel cavity, so that the valve plates are smooth to open and close, and when the valve plates are in the first position and the second position, the valve plates, the ball body and the pneumatic device are mutually interlocked to ensure the safety of opening and closing.

Description

Gate valve

Technical Field

The invention relates to the technical field of valves, in particular to a gate valve.

Background

Gate valves are one of the most commonly used shut-off valves, mainly for switching on or shutting off the medium in a pipeline. The gate valve has the advantages of small fluid resistance, labor saving on and off, unrestricted medium flow and the like, and is widely applied to pipelines with medium and large diameters.

In the prior art, the valve body of the gate valve moves linearly and is rigidly abutted against the pipe wall in the process of cutting off the pipeline, so that the valve body is easy to damage, and the service life of the valve body is reduced.

Disclosure of Invention

The invention aims to provide a gate valve, which solves the problem that a valve body is easy to damage when cutting off a pipeline.

To achieve the purpose, the invention adopts the following technical scheme:

a gate valve, comprising:

the valve body is provided with a flow channel cavity and a control cavity which are communicated with each other, the flow channel cavity extends along the X-axis direction, and the control cavity extends along the Z-axis direction;

the two valve plates are arranged in the valve body and used for opening and closing the flow channel cavity, and the two valve plates are opposite along the X-axis direction and are subjected to elastic force close to each other;

the pneumatic device is sealed to extend into the valve body and simultaneously drives the two valve plates to reciprocate between a first position for closing the flow passage cavity and a second position for opening the flow passage cavity; and

the ball body is clamped between each valve plate and the pneumatic device and can roll along the Z-axis direction, wherein:

when the valve plate is in the first position and the second position, the valve plate, the pneumatic device and the ball are mutually locked.

As a preferable scheme of the gate valve, the opposite surfaces of the two valve plates are respectively provided with a first limit groove extending along the Z-axis direction;

the pneumatic device is provided with a second limit groove extending along the Z-axis direction;

the ball body is arranged between the first limit groove and the second limit groove which are opposite in rolling way.

As a preferable mode of the gate valve, the first limit groove is sequentially provided with a first spherical groove and a second spherical groove which can form surface contact with the ball body along the direction of the first position to the second position, a first groove channel is arranged between the first spherical groove and the second spherical groove, and the first spherical groove covers less surface area of the ball body than the second spherical groove;

the second limiting groove is provided with a third spherical groove and a fourth spherical groove which can form surface contact with the spheres along the direction of the first position pointing to the second position, a second groove channel is arranged between the third spherical groove and the fourth spherical groove, the third spherical groove is more than the fourth spherical groove to cover the surface area of the spheres, and the third spherical groove is more than the fourth spherical groove, wherein:

when the valve plate is in the first position, the ball is locked between the first spherical groove and the fourth spherical groove, and when the valve plate is in the second position, the ball is locked between the second spherical groove and the third spherical groove.

As the preferable scheme of the gate valve, at least two first limit grooves are formed in each valve plate, the pneumatic device is provided with second limit grooves in one-to-one correspondence, and one sphere is arranged between each group of opposite first limit grooves and second limit grooves.

As a preferable mode of the gate valve, each first limit groove is sequentially arranged on a central line of the gate valve extending along the Z-axis direction on each gate plate.

As a preferable mode of the gate valve, an elastic member for providing the elastic force is provided between the two valve plates, and the elastic member is provided with:

a base provided with a base lip extending in the Y-axis direction and facing the pneumatic device;

and a plurality of elastic limbs arranged on the base lip along the Y-axis direction, wherein one part of the elastic limbs are connected with one valve plate, and the other part of the elastic limbs are connected with the other valve plate.

As a preferable scheme of the gate valve, the number of the elastic limbs is four, two outer elastic limbs are connected with one valve plate, and two inner elastic limbs are connected with the other valve plate;

the first limit groove is arranged between the two inner elastic limbs.

As a preferable aspect of the gate valve, the pneumatic device includes:

the cylinder sleeve is arranged outside the valve body and extends along the Z-axis direction;

a piston slidably disposed between two ends within the cylinder sleeve; and

and one end of the piston rod is connected with the piston, and the other end of the piston rod extends into the valve body and is movably abutted against the ball body.

As a preferable aspect of the gate valve, the pneumatic device further includes:

the ventilation seat is connected with one end of the cylinder sleeve, and is provided with two air inlet channels;

the two air passage columns are arranged in the cylinder sleeve along the Z-axis direction and are communicated with the air inlet channels in a one-to-one correspondence manner, and each of the two air passage columns is provided with an air outlet and is positioned at the opposite two ends; and

and the electromagnetic valve can selectively open and close the two air inlet channels of the ventilation seat.

and the micro switch is arranged at two ends of the cylinder sleeve, and the micro switch responds to contact with the piston.

The invention has the beneficial effects that: the two valve plates are clamped between the valve plates and the pneumatic device by the elastic force of the two valve plates, the pneumatic device drives the valve plates to roll relative to the valve plates and the pneumatic device in the opening and closing process of the flow channel cavity, so that the valve plates are smoothly opened and closed, and when the valve plates are in the first position and the second position, the valve plates, the balls and the pneumatic device are mutually interlocked, so that the safety of opening and closing is ensured.

Drawings

Fig. 1 is a schematic structural view of a gate valve according to an embodiment of the present application;

FIG. 2 is an exploded view of the gate valve shown in FIG. 1;

FIG. 3 is an axial cross-sectional view of a valve plate in a gate valve according to an embodiment of the present application in a first position;

FIG. 4 is an axial cross-sectional view of a valve plate in a gate valve according to an embodiment of the present application in a second position;

FIG. 5 is a side view of a valve plate in a gate valve provided in an embodiment of the present application;

FIG. 6 is a side view of a piston rod in a gate valve provided in an embodiment of the present application;

fig. 7 is an exploded view of a part of the structure of a gate valve provided in an embodiment of the present application;

fig. 8 is a schematic structural view of an elastic member of a gate valve according to an embodiment of the present application.

In the figure:

1-a valve body; 11-a runner cavity; 12-a control chamber;

2-a valve plate; 20-a first limit groove; 201-a first spherical groove; 202-a second spherical groove; 203-a first channel;

3-pneumatic means; 30-a second limit groove; 301-a third spherical groove; 302-fourth spherical groove; 303-a second channel; 31-cylinder sleeve; 32-a piston; 33-a piston rod; 34-a ventilation seat; 35-airway column; 36-an electromagnetic valve; 37-micro switch;

4-sphere;

5-an elastic member; 50-base; 501-a base lip; 51-elastic limb.

Detailed Description

The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.

In the description of the present invention, unless explicitly stated and limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "right", etc. orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and simplicity of operation, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for distinguishing between them.

The present invention provides a gate valve, as shown in fig. 1-4, comprising a valve body 1, a valve plate 2, a pneumatic device 3 and a ball 4.

The valve body 1 is provided with a flow passage cavity 11 and a control cavity 12 which are communicated with each other, the flow passage cavity 11 extends along the X-axis direction, and the control cavity 12 extends along the Z-axis direction. As shown in fig. 1 to 3, the X-axis direction is the front-back direction, the Y-axis direction is the left-right direction, the Z-axis direction is the vertical direction, and the X-axis, the Y-axis and the Z-axis are mutually perpendicular. That is, the flow path chamber 11 defines a flow path extending from front to back, and the control chamber 12 is disposed above the flow path chamber 11, with the control chamber 11 communicating downward in the vertical direction.

In the present embodiment, the cross section of the flow channel chamber 11 in the X-Y axis direction is provided as a circular surface.

The valve plates 2 are provided in two, the two valve plates 2 are opposed in the X-axis direction and receive elastic forces close to each other, and the two valve plates 2 are used to open and close the flow passage chamber 11. The valve plate 2 is movable in a vertical direction, i.e. its travel is in a vertical direction.

Optionally, one of the valve plates 2 is provided with a sealing ring at the end face facing away from the other valve plate 2.

A part of the pneumatic device 3 is arranged above the control chamber 12 of the valve body 1, and another part of the pneumatic device 3 extends sealingly into the valve body 1 and drives the two valve plates 2 to reciprocate between a first position closing the flow channel chamber 11 and a second position opening the flow channel chamber 11. In this embodiment, the first position is that the pneumatic device 3 drives the valve plate 2 to move downwards to the lowest end of its own travel, and the flow channel cavity 11 is closed at this time; the second position is the uppermost end of the stroke of the valve plate 2 driven by the pneumatic device 3 to move upwards, and the flow channel cavity 11 is opened at the moment.

The flow channel chamber 11 is partially opened when the valve plate 2 is positioned between the first position and the second position.

The sphere 4 is clamped between each valve plate 2 and the pneumatic device 3 and can roll along the Z-axis direction, on one hand, because the two valve plates 2 are mutually close, the pneumatic device 3 extends between at least two valve plates 2, and then the sphere 4 can be clamped, when the pneumatic device 3 moves up and down, the sphere 4 can roll between the valve plates 2 and the pneumatic device 3, and when the valve plates 2 are at the first position and the second position, the valve plates 2, the pneumatic device 3 and the sphere 4 are mutually interlocked, so that the opening and closing safety is ensured.

Referring to fig. 5 to 6, the opposite surfaces of the two valve plates 2 are provided with first limit grooves 20 extending along the Z-axis direction, the front and rear surfaces of the pneumatic device 3 are provided with second limit grooves 30 extending along the Z-axis direction, and the ball 4 is rollably disposed between the opposite first limit grooves 20 and second limit grooves 30. It will be appreciated that at least part of the first and second limiting grooves 20, 30 in the Z-axis direction overlap and are opposed in the X-axis direction, so that one ball 4 can be accommodated.

The valve plate 2 and the pneumatic device 3 can limit the position along the Z-axis direction through the ball 4, and can only move relatively along the Z-axis direction.

The first limiting groove 20 is provided with a first spherical groove 201 and a second spherical groove 202 which can form surface contact with the ball 4 from bottom to top in sequence, a first groove channel 203 is arranged between the first spherical groove 201 and the second spherical groove 202, and the first spherical groove 201 covers less surface area of the ball 4 than the second spherical groove 202. The volume of the sphere 4 protruding from the surface of the valve plate 2 when the first spherical groove 201 is larger than the volume protruding from the surface of the valve plate 2 when the second spherical groove 202 is. The ball 4 is able to roll from one of the first spherical groove 201 and the second spherical groove 202 through the first channel 203 to the other of the first spherical groove 201 and the second spherical groove 202, in which process the ball 4 is restrained by the first restraining groove 20.

The second limiting groove 30 is sequentially provided with a third spherical groove 301 and a fourth spherical groove 302 which can form surface contact with the ball 4 from bottom to top, a second groove 303 is arranged between the third spherical groove 301 and the fourth spherical groove 302, and the third spherical groove 301 covers more surface area of the ball 4 than the fourth spherical groove 302. The volume of the sphere 4 protruding from the surface of the valve plate 2 at the time of the third spherical groove 301 is larger than the volume protruding from the surface of the valve plate 2 at the time of the fourth spherical groove 302. The ball 4 can roll from one of the third spherical groove 301 and the fourth spherical groove 302 through the second channel 303 to the other of the third spherical groove 301 and the fourth spherical groove 302, in which process the ball 4 is restrained by the second restraining groove 30.

In the present embodiment, the shapes of the first spherical groove 201 and the fourth spherical groove 302 are set to the same structure, and the shapes of the second spherical groove 202 and the third spherical groove 301 are set to the same structure, so as to save the grooving cost.

As shown in fig. 3, 5 and 6, when the valve plate 2 is located at the first position, the ball 4 is locked between the first spherical groove 201 of the valve plate 2 and the fourth spherical groove 302 of the pneumatic device 3. At this time, the pneumatic device 3 cannot continue the downward movement.

As shown in fig. 4-6, when the valve plate 2 is in the second position, the ball 4 is locked between the second spherical groove 202 of the valve plate 2 and the third spherical groove 301 of the pneumatic device 3. At this time, the air-operated device 3 cannot continue upward movement.

Further, as shown in fig. 3, two first limiting grooves 20 are formed in each valve plate 2, correspondingly, second limiting grooves 30 corresponding to each other are formed in the pneumatic device 3, and a ball 4 is arranged between each set of the first limiting grooves 20 and the second limiting grooves 30 which are opposite to each other.

The provision of a plurality of first and second limiting grooves 20, 30, i.e. more sliding contact areas, can ensure stability when the pneumatic device 3 drives the valve body 2 to move up and down.

Further, on each valve plate 2, two first limit grooves 20 are arranged in sequence along the Z-axis direction.

In this embodiment, the two first limiting grooves 20 are arranged along the vertical center line of the valve plate 2, i.e., balance of the left and right sides of the valve plate 2 is maintained.

With continued reference to fig. 7, an elastic member 5 for providing the above-described elastic force is provided between the two valve plates 2. In this embodiment, the elastic member 5 is provided as a stainless steel sheet having good rust prevention and strength characteristics.

As shown in fig. 7 and 8, the elastic member 5 includes a base 50 provided with a base lip 501 extending in the Y-axis direction and facing the air-operated device 3, and a plurality of elastic limbs 51 arranged on the base lip 501 in the Y-axis direction, one of the elastic limbs 51 being connected to one of the valve plates, and the other elastic limb 51 being connected to the other valve plate 2.

In this embodiment, there are four elastic limbs 51, two outer elastic limbs 51 are connected to one valve plate 2, and two inner elastic limbs 51 are connected to the other valve plate 2. By this symmetrical arrangement, the balance of the elastic member 5 in the left-right direction is maintained while a space is left in the middle, so that the up-down movement of the air-operated device 3 is not interfered.

Further, the first limiting groove 20 is provided between the two inner elastic limbs 51 so as not to interfere with the rolling of the ball 4, and also to limit the ball 4, preventing the ball from moving in the left-right direction.

It should be noted that, each elastic limb 51 is provided with a positioning hole, and the valve plate 2 is provided with a threaded hole corresponding to each positioning hole, and the positioning holes on the elastic limbs 51 can be penetrated through the bolts to be connected to the threaded holes of the valve plate 2, so as to connect the elastic piece 5 to the valve plate 2.

With continued reference to fig. 2 and 7, the pneumatic device 3 includes a cylinder sleeve 31, a piston 32, and a piston rod 33.

The cylinder sleeve 31 is disposed outside the valve body 1 and extends in the Z-axis direction, in this embodiment, the cylinder sleeve 31 is provided as a cylindrical tube, the piston 32 is slidably disposed between the upper and lower ends inside the cylinder sleeve 31, and the piston 32 is disc-shaped and abuts against the inner wall of the cylinder sleeve 31. The upper end of the piston rod 33 is connected with the piston 32, the lower end extends into the valve body 1 and movably abuts against the ball body 4, and the piston rod 33 can move up and down synchronously with the piston 32.

It will be appreciated that the piston rod 33 extends into the interior of the valve body 1, and that the second limiting groove 30 is provided on the piston rod 33. In the present embodiment, the piston rod 33 is provided as a rectangular parallelepiped rod having front and rear surfaces.

Further, the pneumatic device 3 further comprises a ventilation seat 34, the ventilation seat 34 being connected to the bottom of the cylinder sleeve 31, the ventilation seat 34 being provided with two air inlet channels.

The pneumatic device 3 further comprises two air passage columns 35, the two air passage columns 35 are arranged in parallel, the two air passage columns 35 are arranged in the cylinder sleeve 31 along the Z-axis direction and are communicated with air inlet channels in a one-to-one correspondence mode, namely, each air inlet channel only supplies air to one air passage column 35, the two air passage columns 35 are respectively provided with an air outlet and are positioned at opposite ends, namely, the air outlet of one air passage column 35 is positioned at the top of the air passage column, the air outlet of the other air passage column 35 is positioned at the bottom of the air passage column, the piston 32 can be pushed to move upwards when the air outlet at the top is discharged, and the piston 32 can be pushed to move downwards when the air outlet at the bottom is discharged.

The solenoid valve 36 selectively opens and closes two air inlet passages of the air vent seat 34, and it is understood that the first air inlet passage is communicated with the air passage column 35 with the air outlet at the top, the second air inlet passage is communicated with the air passage column 35 with the air outlet at the bottom, the piston 32 moves upward when the solenoid valve 36 opens the first air inlet passage, and the piston 32 moves downward when the solenoid valve 36 opens the second air inlet passage.

Further, the pneumatic device 3 further includes a micro switch 37, the micro switch 37 being provided at both ends of the cylinder sleeve 31, and the pneumatic device 3 being capable of being brought into contact with the piston 32 and responding after the contact. It will be appreciated that when the plunger 32 contacts the microswitch 37, the microswitch 37 will signal the external system and the system will process either mode one or mode two depending on the signal: the first mode is to keep the current working condition; the second way opens the other side air passage column 35 to steer the piston 32.

According to the gate valve, the two valve plates 2 are clamped between the valve plates 2 and the pneumatic device 3 by the elastic force of the two valve plates 2, the pneumatic device 3 drives the valve plates 2 to roll relative to the valve plates 2 and the pneumatic device 3 in the opening and closing process flow channel cavity 11, so that the valve plates 2 and the spherical bodies 4 are mutually locked and stopped between the pneumatic device 3 when the valve plates 2 are in the first position and the second position, and the opening and closing safety is guaranteed.

It is to be understood that the above examples of the present invention are provided for clarity of illustration only and are not limiting of the embodiments of the present invention. Various obvious changes, rearrangements and substitutions can be made by those skilled in the art without departing from the scope of the invention. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.

Claims

1. A gate valve, comprising:

the valve comprises a valve body (1) and a control cavity (12), wherein the valve body is provided with a runner cavity (11) and a control cavity (12) which are mutually communicated, the runner cavity (11) extends along the X-axis direction, and the control cavity (12) extends along the Z-axis direction;

two valve plates (2) arranged in the valve body (1) and used for opening and closing the flow channel cavity (11), wherein the two valve plates (2) are opposite along the X-axis direction and are subjected to elastic force close to each other;

a pneumatic device (3) which extends into the valve body (1) in a sealing manner and drives the two valve plates (2) to reciprocate between a first position for closing the flow passage cavity (11) and a second position for opening the flow passage cavity (11); and

and the ball body (4) is clamped between each valve plate (2) and the pneumatic device (3) and can roll along the Z-axis direction, wherein:

when the valve plate (2) is in the first position and the second position, the valve plate (2), the pneumatic device (3) and the sphere (4) are mutually locked.

2. Gate valve according to claim 1, characterized in that the opposite surfaces of both valve plates (2) are provided with a first limit groove (20) extending in the Z-axis direction;

the pneumatic device (3) is provided with a second limit groove (30) extending along the Z-axis direction;

the ball body (4) is arranged between the first limit groove (20) and the second limit groove (30) which are opposite in a rolling way.

3. The gate valve according to claim 2, characterized in that the first limit groove (20) is provided with a first spherical groove (201) and a second spherical groove (202) which can form surface contact with the ball (4) in sequence along the direction of the first position to the second position, a first groove channel (203) is arranged between the first spherical groove (201) and the second spherical groove (202), and the first spherical groove (201) covers less surface area of the ball (4) than the second spherical groove (202);

the second limiting groove (30) is sequentially provided with a third spherical groove (301) and a fourth spherical groove (302) which can form surface contact with the sphere (4) along the direction of the first position pointing to the second position, a second groove channel (303) is arranged between the third spherical groove (301) and the fourth spherical groove (302), and the third spherical groove (301) is more than the fourth spherical groove (302) to cover the surface area of the sphere (4), wherein:

when the valve plate (2) is located at the first position, the sphere (4) is locked between the first spherical groove (201) and the fourth spherical groove (302), and when the valve plate (2) is located at the second position, the sphere (4) is locked between the second spherical groove (202) and the third spherical groove (301).

4. Gate valve according to claim 2, characterized in that at least two first limit grooves (20) are provided on each valve plate (2), the pneumatic means (3) are provided with one-to-one corresponding second limit grooves (30), and one ball (4) is provided between each set of opposite first limit grooves (20) and second limit grooves (30).

5. Gate valve according to claim 4, characterized in that each first limit groove (20) is arranged in turn on each valve plate (2) on a center line of the valve plate (2) extending in the Z-axis direction.

6. Gate valve according to claim 2, characterized in that between two of said valve plates (2) an elastic member (5) is provided providing said elastic force, said elastic member (5) being provided with:

a base (50) provided with a base lip (501) extending in the Y-axis direction and facing the pneumatic device (3);

and a plurality of elastic limbs (51) arranged on the base lip (501) along the Y-axis direction, wherein one part of the elastic limbs (51) is connected with one valve plate (2), and the other part of the elastic limbs (51) is connected with the other valve plate (2).

7. Gate valve according to claim 6, characterized in that said elastic limbs (51) are four in total, two outer elastic limbs (51) being connected to one of said valve plates (2), two inner elastic limbs (51) being connected to the other of said valve plates (2);

the first limiting groove (20) is arranged between the two inner elastic limbs (51).

8. Gate valve according to any of claims 1-7, characterized in that the pneumatic means (3) comprise:

a cylinder sleeve (31) which is provided outside the valve body (1) and extends in the Z-axis direction;

a piston (32) slidably disposed between both ends within the cylinder sleeve (31); and

and a piston rod (33) with one end connected with the piston (32) and the other end extending into the valve body (1) and movably abutting against the ball body (4).

9. Gate valve according to claim 8, characterized in that the pneumatic means (3) further comprise:

a ventilation seat (34) connected with one end of the cylinder sleeve (31), wherein the ventilation seat (34) is provided with two air inlet channels;

the two air passage columns (35) are arranged in the cylinder sleeve (31) along the Z-axis direction and are communicated with the air inlet channels in a one-to-one correspondence manner, and the two air passage columns (35) are respectively provided with an air outlet and are positioned at the opposite two ends; and

a solenoid valve (36) selectively opens and closes two intake passages of the breather seat (34).

10. Gate valve according to claim 9, characterized in that the pneumatic device (3) further comprises:

and micro-switches (37) are arranged at two ends of the cylinder sleeve (31), and the micro-switches (37) are in response to contact with the piston (32).