CN215980972U

CN215980972U - One-way valve

Info

Publication number: CN215980972U
Application number: CN202121123672.3U
Authority: CN
Inventors: 宋治国; 金钜; 王傅钢
Original assignee: Dunan Automotive Thermal Management Technology Co Ltd
Current assignee: Dunan Automotive Thermal Management Technology Co Ltd
Priority date: 2021-05-24
Filing date: 2021-05-24
Publication date: 2022-03-08
Anticipated expiration: 2031-05-24

Abstract

The utility model relates to the technical field of valves, in particular to a one-way valve. The utility model provides a one-way valve which comprises a valve body and a piston unit, wherein a valve cavity and a valve port are arranged in the valve body, the valve port is positioned in the valve cavity, and the piston unit is arranged in the valve cavity and can move along the axis of the valve body so as to open/close the valve port; the check valve further comprises a clamping ring assembly, the clamping ring assembly guides the movement of the piston unit in the valve body and limits the extreme movement position of the piston unit, an elastic buffer opening is formed in the clamping ring assembly, and the elastic buffer opening is used for clamping the clamping ring assembly into the valve body to provide an elastic space. Compared with the prior art, the utility model has the advantages that: through set up snap ring subassembly in the valve body for snap ring subassembly can satisfy simultaneously piston unit direction and can also be convenient for install under spacing prerequisite, thereby improved snap ring subassembly's assembly efficiency.

Description

One-way valve

Technical Field

The utility model relates to the technical field of valves, in particular to a one-way valve.

Background

A check valve is a valve that prevents a liquid from flowing backward by allowing the liquid to flow only in one direction and suppressing the liquid from flowing in the opposite direction, and is provided in a hydraulic circuit or a pipe of a refrigeration cycle.

The snap ring and the guide piece in the existing one-way valve are usually arranged at different positions in the valve body, so that the assembly of the snap ring and the guide piece in the valve body is time-consuming and labor-consuming, and the difficulty of installation and processing is increased.

SUMMERY OF THE UTILITY MODEL

In view of the above, the present invention provides a check valve that is easy to install.

In order to solve the technical problems, the utility model provides the following technical scheme:

a check valve comprises a valve body and a piston unit, wherein the valve body is internally provided with a valve cavity and a valve port, the valve port is positioned in the valve cavity, and the piston unit is arranged in the valve cavity and can move along the axis of the valve body so as to open/close the valve port; the check valve further comprises a clamping ring assembly, the clamping ring assembly guides the piston unit to move in the valve body and limit the limit movement position of the piston unit, an elastic buffer opening is formed in the clamping ring assembly, and the elastic buffer opening is used for clamping the clamping ring assembly into the valve body to provide an elastic space.

It can be understood that the snap ring assembly is arranged in the valve body, so that the snap ring assembly can be conveniently installed on the premise of meeting the guide and limiting of the piston unit, and the assembling efficiency of the snap ring assembly is improved.

In one embodiment, the snap ring assembly includes a snap ring configured to guide movement of the piston unit within the valve body and limit the extreme positions of movement of the piston unit; the snap ring includes interconnect's spacing portion and guide part, spacing portion at least part with the valve body inner wall contact and the joint in the valve body, the guide part set up in spacing portion encircles in the space that forms, the elasticity buffering mouth is seted up in the guide part or on the spacing portion.

It is understood that, by providing the elastic buffer port on the guide portion or the stopper portion, an elastic movement space is provided for the stopper portion to move toward/away from the guide portion or the stopper portion to move toward/away from each other, so that the clip ring assembly can be mounted in the valve body.

In one embodiment, the elastic buffer opening is opened on the limiting portion, a bent portion is arranged on the limiting portion, the bent portion is bent towards the direction of the guiding portion, and the elastic buffer opening is formed between the bent portion and the guiding portion.

In one embodiment, the elastic buffer opening is opened on the limit portion, an abutting portion is arranged on the limit portion, the abutting portion extends towards the direction of the guide portion, the abutting portion can abut against the guide portion, and the elastic buffer opening is formed between the abutting portion and the limit portion.

In one embodiment, the piston unit comprises a piston rod and a piston head which are fixed to each other, the piston rod extends from the piston head towards the direction of the clamping ring, and when the piston unit moves towards the direction of the clamping ring, the piston head can abut against the connecting position of the limiting part and the guide part so as to limit the limit movement position of the piston unit in the valve cavity.

In one embodiment, the piston unit further includes an elastic member, the elastic member is sleeved on the piston rod, one end of the elastic member is connected to the piston head, and the other end of the elastic member abuts against the guide portion to limit the limit movement position of the piston unit in the valve cavity.

In one embodiment, the snap ring assembly further comprises a gasket, a through hole is formed in the guide portion, the gasket is connected to one end, close to the piston unit, of the guide portion, and the piston rod can penetrate through the through hole through the gasket and slide relative to the through hole.

It will be appreciated that the through hole enables direct guidance of the piston unit by sliding the piston rod relative to the through hole.

In one embodiment, the snap ring assembly further comprises a guide member, and the guide member is fixedly connected with the snap ring assembly through the through hole and used for guiding the movement direction of the piston unit.

In one embodiment, the guide is at least partially mounted in the through hole.

In one embodiment, the guide member comprises a main body part and an extension part which are connected with each other, the main body part is limited and installed in the through hole, the part of the main body part, which extends out of the through hole, extends in the radial direction and forms the extension part, and the extension part can abut against the piston unit to limit the limit movement position of the piston unit.

In one embodiment, the valve body is internally provided with the mounting groove, the snap ring component is partially installed in the mounting groove, the snap ring component is provided with a plane structure, and when the snap ring component is installed in the mounting groove, the plane structure is tightly attached to the inner wall of the mounting groove.

It can be understood that the plane structure is arranged on the snap ring assembly, so that two ends of the cross section of the snap ring assembly are planes, and the limiting reliability of the snap ring assembly is improved when the snap ring assembly is installed on the installation groove.

Compared with the prior art, the check valve provided by the utility model has the advantages that the snap ring assembly is arranged in the valve body, so that the snap ring assembly can be conveniently installed on the premise of meeting the guide and limit of the piston unit, and the assembly efficiency of the snap ring assembly is improved.

Drawings

FIG. 1 is a schematic structural diagram of a first embodiment of a check valve provided in the present invention;

FIG. 2 is a schematic structural diagram of a second embodiment of a check valve provided in the present invention;

FIG. 3 is a schematic structural diagram of a third embodiment of a check valve provided by the present invention;

FIG. 4 is a schematic structural view of an embodiment of a snap ring provided in the present invention;

FIG. 5 is a schematic structural view of another embodiment of a snap ring provided in the present invention;

FIG. 6 is a schematic structural view of another embodiment of a snap ring provided in the present invention;

fig. 7 is a schematic structural diagram of a snap ring according to still another embodiment of the present invention.

The symbols in the drawings represent the following meanings:

100. a one-way valve; 10. a valve body; 11. a valve cavity; 12. a valve port; 13. mounting grooves; 14. an inlet; 15. an outlet; 20. a piston unit; 21. a piston head; 22. a piston rod; 23. an elastic member; 30. a snap ring assembly; 31. a snap ring; 311. a limiting part; 3111. a bending section; 3112. an abutting portion; 312. a guide portion; 3121. a through hole; 3122. an expansion section; 3123. a tightening part; 313. an elastic buffer port; 314. a planar structure; 32. a gasket; 33. a guide member; 331. a guide hole; 332. a main body portion; 333. an extension portion; 334. a step portion.

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.

It will be understood that when an element is referred to as being "mounted on" another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present. When an element is referred to as being "secured to" another element, it can be directly secured to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the utility model herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1 to 7, the present invention provides a check valve 100, which is applied to an air conditioner to prevent a refrigerant from flowing backwards, and also to a hydraulic system to prevent a reverse flow of oil, or a pneumatic system to prevent a reverse flow of compressed air.

Specifically, the check valve 100 provided by the utility model comprises a valve body 10 and a piston unit 20, wherein the valve body 10 is internally provided with a valve cavity 11 and a valve port 12, the valve port 12 is positioned in the valve cavity 11, and the piston unit 20 is arranged in the valve cavity 11 and can move along the axis of the valve body 10 to open/close the valve port 12; the check valve 100 further includes a snap ring assembly 30, the snap ring assembly 30 guides the movement of the piston unit 20 in the valve body 10 and limits the extreme movement position of the piston unit 20, an elastic buffer opening 313 is formed on the snap ring assembly 30, and the elastic buffer opening 313 provides an elastic space for the snap ring assembly 30 to be clamped into the valve body 10.

It should be noted that, the snap ring and the guide in the existing check valve are usually disposed at different positions in the valve body, so that the assembly of the snap ring and the guide in the valve body is time-consuming and labor-consuming, and the difficulty of installation and processing is increased. In the present embodiment, the snap ring assembly 30 is disposed in the valve body 10, so that the snap ring assembly 30 can be conveniently installed on the premise of satisfying the guiding and limiting of the piston unit 20, thereby improving the assembly efficiency of the snap ring assembly 30.

The valve body 10 is preferably formed in a hollow structure as a whole in a long cylindrical shape, but the valve body 10 may be formed in other shapes such as a rectangular parallelepiped shape in other embodiments, and the shape is not limited herein.

Preferably, in this embodiment, the valve body 10 is made of cast copper; of course, in other embodiments, the valve body 10 may be made of other materials such as cast iron, and is not limited herein.

The valve body 10 is provided with an inlet 14 and an outlet 15 which are communicated with each other, the valve port 12 is located between the inlet 14 and the outlet 15, and the refrigerant in the valve cavity 11 flows from the inlet 14 to the outlet 15, but cannot flow from the outlet 15 to the inlet 14, which is the existing characteristic of the check valve 100, and will not be described herein again.

Specifically, the piston unit 20 is located within the valve chamber 11 and between the valve port 12 and the outlet 15. The piston unit 20 is movable in the valve chamber 11, i.e., the piston unit 20 is movable from the outlet 15 toward the valve port 12 or from the valve port 12 toward the outlet 15, thereby opening/closing the valve port 12.

It should be noted that, when the piston unit 20 moves from the outlet 15 toward the valve port 12 and abuts against the valve port 12, the check valve 100 is in the closed state; when the piston unit 20 moves from the valve port 12 toward the outlet 15 and separates from the valve port 12, the check valve 100 is in an open state.

Further, the snap ring assembly 30 includes a snap ring 31, and the snap ring 31 can guide the movement of the piston unit 20 within the valve body 10 and limit the extreme movement position of the piston unit 20.

Preferably, in the present embodiment, in order to fit the cylindrical structure of the valve body 10, the snap ring 31 is also provided as an annular structure opposite to the valve body 10; of course, in other embodiments, the snap ring 31 may be provided in other shapes, and is not limited in particular.

As shown in fig. 1-3, the present application provides three embodiments of a one-way valve 100 that include three embodiments of snap ring assembly 30 arrangements, which are described in turn herein.

Example one

Referring to fig. 1, the piston unit 20 includes a piston rod 22 and a piston head 21 fixed to each other, the piston rod 22 extends from the piston head 21 toward the snap ring 31, the piston unit 20 further includes an elastic member 23, the elastic member 23 is sleeved on the piston rod 22, one end of the elastic member 23 is fixedly connected to the piston head 21, and the other end of the elastic member 23 abuts against the snap ring assembly 30.

Preferably, in the present embodiment, the elastic member 23 is a spring; of course, in other embodiments, the elastic member 23 may also adopt other elastic structures, and is not limited herein.

In the present embodiment, the snap ring assembly 30 further includes a guide 33, a through hole 3121 is formed in a surrounding space of the guide portion 312, the guide 33 is snap-fitted to the snap ring 31 through the through hole 3121, and the guide 33 is entirely located in the through hole 3121, that is, a length of the guide 33 in the axial direction of the valve body 10 is less than or equal to a length of the snap ring 31 in the axial direction of the valve body 10.

Furthermore, the guide member 33 is provided with a guide hole 331, one end of the piston rod 22 away from the piston head 21 can extend into the guide hole 331 and move along the axial direction of the valve body 10 relative to the guide hole 331, and the guide hole 331 can guide the movement direction of the piston unit 20 in the valve cavity 11.

It should be noted that, when the piston unit 20 moves towards the snap ring 31 and abuts against the snap ring 31, the elastic member 23 can abut against the guide member 33 for limiting, and after the elastic member 23 is further compressed, the piston head 21 can abut against the limiting portion 311 for limiting, so that the limiting portion 311 and the guide member 33 jointly achieve the limiting effect on the piston unit 20 to limit the limit movement position of the piston unit 20 in the valve cavity 11.

Example two

As shown in fig. 2, the structure of the second embodiment is substantially the same as that of the first embodiment, and the same parts can be referred to the explanations of the first embodiment, which will not be described herein again, but the differences are:

in this embodiment, the guide 33 includes a main body portion 332 and an extending portion 333 connected to each other, the main body portion 332 is limit-mounted in the through hole 3121, a portion of the main body portion 332 extending out of the through hole 3121 extends in the radial direction and forms the extending portion 333, when the piston unit 20 moves towards the snap ring 31 and abuts against the snap ring 31, the elastic member 23 can abut against the extending portion 333 for limiting, after the elastic member 23 is further compressed, the piston head 21 can abut against the limit portion 311 for limiting, and thus, the limit portion 311 and the guide 33 together achieve a limit effect on the piston unit 20 to limit the limit moving position of the piston unit 20 in the valve cavity 11.

It should be noted that, since the extending portion 333 extends along the radial direction of the valve body 10 and the main body portion 332 extends along the axial direction of the valve body 10, a step portion 334 is formed at the connecting position of the main body portion 332 and the extending portion 333, when the elastic member 23 abuts against the extending portion 333, the elastic member 23 applies a pushing force to the extending portion 333 in the direction toward the outlet 15, and at this time, the step portion 334 abuts against the snap ring 31 to form a limit, so that the guide member 33 is prevented from falling off from the through hole 3121, and safety and reliability are improved.

Further, the guide portion 312 is further provided with an expansion portion 3122 and a tightening portion 3123 which are connected to each other, the expansion portion 3122 and the tightening portion 3123 jointly enclose a through hole 3121, that is, when the guide member 33 is installed in the through hole 3121, the guide member 33 can be snapped into the through hole 3121 only by expanding the expansion portion 3122, and then the guide member 33 needs to be limited and fixed by using the tightening function of the tightening portion 3123, so that the guide member 33 is prevented from falling off from the through hole 3121, and the normal operation of the check valve 100 is prevented from being affected.

EXAMPLE III

As shown in fig. 3, the structure of the third embodiment is substantially the same as that of the first embodiment, and the same parts can be referred to the explanations of the first embodiment, which will not be described herein again, but the differences are as follows:

in this embodiment, the snap ring assembly 30 further includes a spacer 32, the guide portion 312 has a through hole 3121, the spacer 32 is connected to one end of the guide portion 312 close to the piston unit 20, and the piston rod 22 can be inserted into the through hole 3121 through the spacer 32 and can slide relative to the through hole 3121.

It is noted that the through hole 3121 realizes direct guidance of the piston unit 20 by the piston rod 22 sliding with respect to the through hole 3121.

The specific structure of the snap ring 31 will be described in detail with reference to the first embodiment and the third embodiment.

The valve body 10 is internally provided with a mounting groove 13, the clamping ring 31 is partially mounted in the mounting groove 13, the clamping ring 31 is provided with a plane structure 314, and when the clamping ring 31 is mounted in the mounting groove 13, the plane structure 314 is tightly attached to the inner wall of the mounting groove 13.

Specifically, by arranging the plane structure 314 on the snap ring 31, two ends of the cross section of the snap ring 31 are planes, so that the limiting reliability of the snap ring 31 is increased when the snap ring 31 is installed in the installation groove 13.

To facilitate understanding of what is the plane structure 314, assuming a cutting process situation for the snap ring 31, when the snap ring 31 is installed in the installation groove 13, two end surfaces of the snap ring 31 along the axial direction of the valve body 10 will be attached to the groove walls of two sides of the installation groove 13. Because the outer surface of the snap ring 31 is arc-shaped, the situation of instable installation caused by too small contact area when the snap ring is attached to the groove wall is assumed, in order to solve the problem, a cutting knife is used for cutting off arc-shaped surfaces at two ends of the snap ring 31, which are in contact with the groove wall, along the direction perpendicular to the axis of the valve body 10, so that the contact area between two end surfaces of the snap ring 31 and the groove wall is increased, and the installation reliability of the snap ring 31 is further enhanced. Of course, it should be noted that the plane structure 314 may be integrally formed when the snap ring 31 is machined, or may not need to be cut later.

In one embodiment, referring to fig. 4, the snap ring 31 includes a limiting portion 311 and a guiding portion 312 connected to each other, the limiting portion 311 at least partially contacts with an inner wall of the valve body 10 and is clamped in the valve body 10, and the guiding portion 312 is disposed in a space formed by the limiting portion 311.

In this embodiment, since the valve body 10 is cylindrical, the limiting portion 311 is correspondingly installed on the inner wall of the valve body 10, in order to facilitate the limiting installation of the snap ring 31 in the valve body 10, the limiting portion 311 is configured to be annular corresponding to the inner wall of the valve body 10, and the guide portion 312 is located in a space formed by the annular limiting portion 311 in a surrounding manner, that is, the guide portion 312 is not in contact with the inner wall of the valve body 10.

Specifically, the elastic buffer port 313 opens on the guide portion 312; through setting up elastic buffer mouth 313 on guide part 312, just make the connection on the snap ring 31 no longer continuous, elastic buffer mouth 313 offer make arbitrary position "disconnection" on guide part 312, so just provide spacing portion 311 towards or keep away from the elastic movement space of guide part 312, the operator can exert external force on spacing portion 311, make spacing portion 311 retract towards the direction of guide part 312, the overall dimension of snap ring 31 obtains contracting, can easily block snap ring 31 into mounting groove 13 this moment, and then loosen the application force to spacing portion 311, make spacing portion 311 expand towards the direction of keeping away from guide part 312 under the effect of self restoring force, so just form spacing connection with mounting groove 13, the installation of snap ring 31 not only is convenient for, the assembly reliability between snap ring 31 and the mounting groove 13 has also been promoted.

It should be noted that, no matter where the elastic buffer opening 313 is formed on the guide portion 312, it is necessary to ensure that the stopper portion 311 and the guide portion 312 are in the connected state.

In one embodiment, as shown in fig. 5, the elastic buffer opening 313 is opened on the position-limiting portion 311; elastic buffer mouth 313 offers and makes arbitrary position "disconnection" on spacing portion 311, so just provide the elastic movement space that is close to or keeps away from each other between the spacing portion 311, the operator exerts external force on spacing portion 311, make between the spacing portion 311 close to each other, the overall dimension of snap ring 31 obtains the shrink, can easily block snap ring 31 into mounting groove 13 this moment, then loosen the application of force to spacing portion 311, make spacing portion 311 keep away from each other under the effect of restoring force itself, so just form spacing connection with mounting groove 13, not only be convenient for the installation of snap ring 31, the assembly reliability between snap ring 31 and mounting groove 13 has also been promoted.

Of course, the elastic buffer opening 313 may also be opened at the connecting position of the limiting part 311 and the guiding part 312; that is, an elastic movement space between the stopper portion 311 and the guide portion 312 to be close to or away from each other is provided, thereby facilitating the installation of the snap ring 31 in the installation groove 13.

In one embodiment, as shown in fig. 6, the stopper 311 is provided with a bent portion 3111, the bent portion 3111 is bent toward the guide 312, and the elastic buffer port 313 is provided on the bent portion 3111.

It should be noted that, through the arrangement of the bent portion 3111, when the bent portions 3111 are "disconnected", an external force is applied to the limiting portion 311 to make the bent portions 3111 approach each other, and since the bent portion 3111 is bent toward the direction of the guiding portion 312, when the bent portions 3111 approach each other and contact each other, the arc-shaped track on the bent portion 3111 provides a tendency of further approaching between the bent portions 3111, thereby further reducing the size of the snap ring 31, further saving the applied force for mounting the snap ring 31, and making the snap ring 31 easy and easy to mount.

In one embodiment, as shown in fig. 7, the stopper portion 311 is provided with an abutting portion 3112, the abutting portion 3112 extends in the direction of the guide portion 312, the abutting portion 3112 can abut against the guide portion 312, and the elastic buffer port 313 is provided between the abutting portion 3112 and the stopper portion 311.

It should be noted that, by the arrangement of the abutting portion 3112, when an external force is applied to the limiting portion 311, since the abutting portion 3112 extends toward the direction of the guide portion 312, when the snap ring 31 is compressed to a certain size, the abutting portion 3112 abuts against the guide portion 312 for limiting the further compression of the snap ring 31, thereby avoiding damage caused by over-compression of the snap ring 31 and further prolonging the service life of the snap ring 31.

It is to be noted that, due to the arrangement of the expanding portion 3122 and the tightening portion 3123 of the guide portion 312, the guide portion 312 has two states, i.e., an expanded state and a natural state, the expanded state is when the guide member 33 is installed in the through hole 3121, and the natural state is when the piston rod 22 directly extends into the through hole 3121, and here, it is to be noted that, when the guide portion 312 is in the natural state, the piston rod 22 is in clearance fit with the through hole 3121 and can slide relative to the through hole 3121.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the utility model. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A check valve comprising a valve body (10) and a piston unit (20), the valve body (10) having a valve chamber (11) therein and a valve port (12), the valve port (12) being located in the valve chamber (11), the piston unit (20) being mounted in the valve chamber (11) and being movable along an axis of the valve body (10) to open/close the valve port (12);

the check valve is characterized in that the check valve further comprises a clamping ring assembly (30), the clamping ring assembly (30) guides the piston unit (20) to move in the valve body (10) and limit the limit movement position of the piston unit (20), an elastic buffer opening (313) is formed in the clamping ring assembly (30), and the elastic buffer opening (313) is used for clamping the clamping ring assembly (30) into the valve body (10) to provide an elastic space.

2. The one-way valve of claim 1, wherein the snap ring assembly (30) includes a snap ring (31), the snap ring (31) being configured to guide movement of the piston unit (20) within the valve body (10) and limit an extreme movement position of the piston unit (20);

snap ring (31) are including interconnect's spacing portion (311) and guide part (312), spacing portion (311) at least part with valve body (10) inner wall contact and joint in valve body (10) are interior, guide part (312) set up in spacing portion (311) encircle in the space that forms, elasticity buffering mouth (313) are seted up in guide part (312) or on spacing portion (311).

3. The non-return valve according to claim 2, characterized in that the resilient relief opening (313) opens onto the stop portion (311), a bend (3111) being provided on the stop portion (311), the bend (3111) being bent towards the guide portion (312), the resilient relief opening (313) being formed between the bend (3111) and the guide portion.

4. The check valve according to claim 2, characterized in that the elastic buffer opening (313) opens onto the stopper portion (311), an abutment portion (3112) is provided on the stopper portion (311), the abutment portion (3112) extends in the direction of the guide portion (312), the abutment portion (3112) is capable of abutting against the guide portion (312), and the elastic buffer opening (313) is formed between the abutment portion (3112) and the stopper portion (311).

5. The check valve according to claim 2, characterized in that the piston unit (20) comprises a piston rod (22) and a piston head (21) fixed to each other, the piston rod (22) extends from the piston head (21) towards the direction of the snap ring (31), and when the piston unit (20) moves towards the direction of the snap ring (31), the piston head (21) can abut against the connection position of the limiting portion (311) and the guide portion (312) to limit the limit movement position of the piston unit (20) in the valve chamber (11).

6. The check valve of claim 5, wherein the piston unit (20) further comprises an elastic member (23), the elastic member (23) is sleeved on the piston rod (22), one end of the elastic member (23) is connected to the piston head (21), and the other end of the elastic member (23) abuts against the guide portion (312) to limit the limit movement position of the piston unit (20) in the valve cavity (11).

7. The check valve as claimed in claim 5, wherein the snap ring assembly (30) further comprises a spacer (32), the guide portion (312) is provided with a through hole (3121), the spacer (32) is connected to one end of the guide portion (312) close to the piston unit (20), and the piston rod (22) can be inserted into the through hole (3121) through the spacer (32) and can slide relative to the through hole (3121).

8. The check valve according to any of claims 1-7, characterized in that the snap ring assembly (30) further comprises a guide (33), the guide (33) being affixed to the snap ring (31) through the through hole (3121) for guiding the direction of movement of the piston unit (20).

9. Non-return valve according to claim 8, characterized in that the guide (33) is at least partially mounted in the through hole (3121).

10. The check valve according to claim 8, characterized in that the guide (33) comprises a main body portion (332) and an extension portion (333) connected with each other, the main body portion (332) is limit-mounted in the through hole (3121), a portion of the main body portion (332) protruding out of the through hole (3121) extends in a radial direction and forms the extension portion (333), and the extension portion (333) can abut against the piston unit (20) to limit an extreme movement position of the piston unit (20).

11. The check valve of claim 1, wherein a mounting groove (13) is formed in the valve body (10), the snap ring assembly (30) is partially mounted in the mounting groove (13), a flat structure (314) is formed on the snap ring assembly (30), and when the snap ring assembly (30) is mounted in the mounting groove (13), the flat structure (314) is tightly attached to the inner wall of the mounting groove (13).