Switch mechanism for plug valve and plug valve

Abstract

The utility model relates to the technical field of plug valves, and discloses a switch mechanism for a plug valve and the plug valve, the switch mechanism comprises an inner switch and a cross block, the inner switch is provided with an operating end and a connecting end, one end of the cross block is connected with the connecting end of the inner switch, the other end of the cross block is connected with a valve core in a valve body, a bushing ring is further fixedly arranged in an operating hole, and the bushing ring is connected with the operating end of the inner switch. A first sealing piece is arranged between the circumferential direction of the bushing ring and the hole wall of the operation hole, and the connecting end of the inner switch penetrates through an inner hole of the bushing ring to be connected with the cross block and is in rotary sealing fit with a second sealing piece installed on the inner hole of the bushing ring. The bushing ring structure is additionally arranged between the valve rod and the hole wall of the operation hole, original rotary sealing between the valve rod and the operation hole is changed into rotary sealing between the valve rod and the bushing ring hole, most of the hole area is sealed through the bushing ring, the sealing area of the valve rod is reduced, and then the area of the valve rod bearing the internal pressure intensity is reduced; furthermore, the rotating friction force of the valve rod is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of oil drilling, and more specifically to a switching mechanism for a plug valve and a plug valve. Background Art

[0002] A plug valve is a quick-opening and closing through valve that realizes opening or closing by rotating 90 degrees to make the channel opening on the valve plug communicate with or separate from the channel opening on the valve body. In the field of oil drilling, the plug valve is widely used in the drill string circulation system and is a manual control valve that can play a role in high-pressure sealing.

[0003] In the existing switching structure of the plug valve, most of the switching hole area is sealed by the valve stem. When there is pressure inside the plug valve, the pressure acts on the valve stem, forming a huge pressure and then a large frictional force, making it very laborious to turn the valve stem to open or close the plug valve, and when the pressure reaches a certain intensity, it is completely impossible for manual operation to turn the valve stem. At the same time, due to the large area sealed by the valve stem and the usually large diameter of the sealing element used, when the switch is turned, the valve stem needs to rotate 90°, and the friction length of the sealing ring is 1 / 4 of the sealing diameter, resulting in easy damage to the sealing element at the switch and causing leakage problems. Summary of the Invention

[0004] In order to solve the problems and deficiencies existing in the above-mentioned prior art, the utility model specifically provides a switching mechanism for a plug valve and a plug valve. By adding a lining ring structure between the inner switch and the hole wall of the operation hole, the original rotary seal between the inner switch and the operation hole is changed to the rotary seal between the inner switch and the inner hole of the lining ring. The outer circumference of the lining ring seals most of the hole area of the operation hole, reducing the sealing area of the inner switch and further reducing the area of the inner switch bearing the internal pressure, and further reducing the rotational friction force of the inner switch. At the same time, the diameter of the inner switch sealing element is reduced, reducing the friction length of the sealing element each time the switch is operated, and improving the service life of the sealing element.

[0005] In order to achieve the above-mentioned invention purpose, the technical solution of the utility model is as follows:

[0006] On the one hand, the utility model provides a switching mechanism for a plug valve. The switching mechanism is arranged in the operation hole on the side wall of the plug valve body and includes an inner switch and a cross block. The inner switch has an operation end and a connection end. One end of the cross block is connected to the connection end of the inner switch, and the other end is connected to the valve core inside the valve body; the switching mechanism further includes a lining ring arranged in the operation hole. A first sealing element is arranged between the circumferential direction of the lining ring and the hole wall of the operation hole. The connection end of the inner switch passes through the inner hole of the lining ring and is connected to the cross block, and forms a rotational sealing fit with a second sealing element installed on the inner hole of the lining ring.

[0007] Preferably, the switch mechanism further includes a limit ring fixed in the operation hole for limiting the rotation angle of the inner switch.

[0008] Preferably, the operating end of the inner switch is rotatably arranged in the inner hole of the limit ring. An arc-shaped limit flange is axially extended and formed on the end face of the operating end. An arc-shaped limit protrusion is axially extended and formed on the end face of the limit ring. The limit flange rotates synchronously with the inner switch and the limit flange can selectively abut against one of the faces of the limit protrusion to limit the counterclockwise and clockwise rotation angles of the inner switch.

[0009] Preferably, a clamping groove is arranged on the end face of the limit ring, and a clamping block is arranged on the hole wall of the operation hole. The clamping block and the clamping groove are in a matching shape, and the clamping block is clamped in the clamping groove.

[0010] Preferably, a convex ring is provided on the inner switch. An arc-shaped limit flange is axially extended and formed on the end face of the convex ring. A stop post is arranged on the end face of the lining ring. The limit flange rotates synchronously with the inner switch and the limit flange can selectively abut against one of the faces of the stop post to limit the counterclockwise and clockwise rotation angles of the inner switch.

[0011] Preferably, a pressing block for limiting the rotation of the lining ring is further arranged in the valve body of the plug valve. One end of the pressing block is connected to the inner wall of the valve body, and a protrusion is arranged at the other end. A notch matching the shape of the protrusion is arranged in the circumferential direction of the lining ring, and the protrusion is inserted into the notch.

[0012] Preferably, the switch mechanism further includes a thrust bearing arranged in the operation hole. After the other end of the inner switch passes through the thrust bearing, the convex ring thereon abuts against one side of the thrust bearing, and the other side of the thrust bearing abuts against the inner wall of the operation hole.

[0013] Preferably, the cross block is a circular plate. First key strips and first key grooves are respectively arranged along the radial direction on both sides of the plate. The first key strips are perpendicular to the first key grooves. Second key strips are arranged on the inner switch. The cross block and the inner switch are connected through the first key grooves and the second key strips; Second key grooves are arranged on the valve core. The cross block and the valve core are connected through the second key grooves and the first key strips.

[0014] Based on the same inventive concept, on the other hand, the present utility model also provides a plug valve, which includes a valve body and a valve core. The valve body is provided with the switch mechanism as described above, and the connection end of the switch mechanism penetrates into the valve body and is connected to the valve core for operating the rotation of the valve core.

[0015] The beneficial effects of the present utility model:

[0016] 1. By adding a lining ring structure between the inner switch and the hole wall of the operation hole, the present utility model changes the original rotary seal between the inner switch and the operation hole into a rotary seal between the inner switch and the inner hole of the lining ring. The outer periphery of the lining ring seals most of the hole area of the operation hole, reducing the sealing area of the inner switch and thus the area of the inner switch bearing the internal pressure, further reducing the rotational friction force of the inner switch. The structure of the present utility model can achieve the purpose of easily rotating the valve core, and thus realize the effect of labor saving.

[0017] 2. The present utility model reduces the diameter of the rotary seal used, reduces the friction length of the seal each time the switch is operated, and improves the service life of the seal.

[0018] 3. The present utility model adds a thrust bearing in the valve body, further reducing the friction force suffered by the inner switch during rotation.

[0019] 4. The present utility model adopts the connection between the inner switch and the valve stem on the cross block. The wrench head bears the eccentric torque of the external operation, avoiding the eccentric wear of the valve stem and improving the sealing effect and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The foregoing and following specific descriptions of the present utility model become clearer when read in conjunction with the following drawings, in which:

[0021] Figure 1 is an enlarged view of the switch mechanism of the present utility model (the thick horizontal line in the figure represents the sealing area of the inner switch);

[0022] Figure 2 is an enlarged view of the switch mechanism of the existing plug valve (the thick horizontal line in the figure represents the sealing area of the valve stem);

[0023] Figure 3 is an exploded view of the plug valve in Embodiment 2;

[0024] Figure 4 is a schematic diagram of the limit fit between the inner switch and the limit ring of the plug valve in Embodiment 2;

[0025] Figure 5 is an enlarged view of the switch mechanism of the plug valve in Embodiment 3 (the thick horizontal line in the figure represents the sealing area of the inner switch);

[0026] Figure 6 is an exploded view of the plug valve in Embodiment 3;

[0027] Figure 7 is a schematic diagram of the structure of the plug valve in Embodiment 4.

[0028] In the drawings:

[0029] 1. Internal switch; 2. Cross block; 3. Bushing ring; 4. First sealing member; 5. Second sealing member; 6. Limiting ring; 7. Limiting flange; 8. Limiting convex block; 9. Block; 10. Slot; 11. Convex ring; 12. Stop column; 13. Pressing block; 14. Notch; 15. Second key strip; 16. Second keyway; 17. Transmission block; 18. Thrust bearing; 101. Wrench head; 102. Valve stem; 131. convex block; 201. First key strip; 202. First keyway; 100. Valve body; 200. Valve core; 300. Operating hole; 400. Valve seat. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solutions in the utility model, the technical solutions for achieving the invention purpose of the utility model will be further described below through several specific embodiments. It should be noted that the technical solutions claimed for protection by the utility model include but are not limited to the following embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the utility model.

[0031] Example 1

[0032] In the switch structure adopted by the existing plug valve, the valve stem is the main component for operating the valve core to rotate, and it seals most of the switch hole area (refer to the attached manual). Figure 2 As shown, the valve stem 1 is rotatably arranged in the operating hole 300 of the valve body 100, and an annular sealing member is arranged on the hole wall of the operating hole 300, and the valve stem 1 and the sealing member on the hole wall of the operating hole form a rotating sealing relationship). Therefore, when there is pressure inside the plug valve, the pressure will act on the valve stem 1 to form a huge pressure, and then form a large friction force, making it very difficult to pull the valve stem 1 externally to open or close the plug valve, and after the pressure reaches a certain intensity, it is completely impossible to pull the valve stem 1 manually. At the same time, since the sealing area of ​​the valve stem 1 is large, the diameter of the commonly used sealing member is also large, and the valve stem 1 usually needs to be rotated 90° when opening or closing the valve. At this time, the friction length of the sealing ring is 1 / 4 of the sealing diameter, which is easy to cause damage to the sealing member at the switch, resulting in leakage problems.

[0033] Based on this, the present utility model proposes a switching mechanism for a cock valve and a cock valve. In the present utility model, the inner switch is the main component provided on the valve body for operating the rotation of the valve core. Its function and role are the same as those of the valve stem, both of which are used to manipulate the valve core to rotate to open or close the valve. By adding a lining ring structure between the inner switch and the hole wall of the operation hole, the original rotary seal between the inner switch and the operation hole is changed to a rotary seal between the inner switch and the inner hole of the lining ring. The outer periphery of the lining ring seals most of the hole area of the operation hole, reducing the sealing area of the inner switch and further reducing the area of the inner switch bearing the internal pressure, thereby further reducing the rotational friction of the inner switch. At the same time, the diameter of the inner switch seal is reduced, reducing the friction length of the seal each time the switch is operated and improving the service life of the seal. The switching mechanism of the present utility model has the effects of saving effort and improving the service life of the inner seal of the valve.

[0034] As a most basic embodiment of the present utility model, this embodiment first discloses a switching mechanism for a cock valve. First, in order to be able to open and close the cock valve, an operation hole 300 is usually provided on the side wall of the cock valve body. A switching mechanism generally corresponds to the operation hole 300. The switching mechanism is usually rotatably arranged in the operation hole 300. The switching mechanism has an operation end and a connection end. The connection end penetrates into the valve body 100 through the operation hole 300 and is combined with the valve core 200 for manipulating the valve core 200 to rotate. The operation end is generally connected to an external operation tool such as a wrench. During operation, the switching mechanism is rotated at the operation end, and the connection end of the switching mechanism drives the valve core 200 to rotate together to realize the opening and closing of the cock valve. Refer to the attached Figure 1 As shown in the figure, in this embodiment, the switching mechanism includes an inner switch 1 and a lining ring 3 located in the operation hole 300. The operation hole 300 is arranged radially on the side wall of the cock valve body and is communicated with the channel inside the valve body 100. The inner switch 1 has an operation end and a connection end. The lining ring 3 is fixedly arranged in the operation hole 300. A circular first seal 4 is provided between the outer peripheral surface of the lining ring 3 and the hole wall of the operation hole 300. The connection end of the inner switch 1 passes through the inner hole of the lining ring 3 and is connected to one end of a cross block 2 arranged inside the valve body 100. The other end of the cross block 2 is torsionally connected to the valve core 200 inside the valve body 100. The operation end of the inner switch 1 is generally connected to an external operation tool; further, a circular second seal 5 is provided on the inner hole wall of the lining ring 3. The connection end of the inner switch 1 forms a rotational sealing and mating relationship with the lining ring 3 through the second seal 5, and the connection end of the inner switch 1 is rotatably arranged in the inner hole of the lining ring 3.

[0035] Comparing the attached Figure 1 and attached Figure 2It can be seen that the inner switch 1 of the present utility model is the main component for operating the rotation of the valve core 200. A lining ring 3 is provided between the inner switch 1 and the hole wall of the operation hole 300. The inner switch 1 does not contact the hole wall of the operation hole 300. Instead, the outer periphery of the lining ring 3 is directly in sealing contact with the hole wall of the operation hole 300 through the first seal 4. Then, the inner switch 1 and the inner hole of the lining ring 3 form a rotational sealing fit relationship through the second seal 5. The present utility model reduces the rotational sealing area of the inner switch 1, thereby reducing the area of the inner switch 1 that bears the internal pressure. Further, the rotational friction of the inner switch 1 is reduced, achieving the effect of labor saving. At the same time, the diameter of the inner switch seal is reduced, and the friction length of the switch seal each time is also reduced, improving the service life of the seal.

[0036] Further, in the embodiment described in this embodiment, the inner switch 1 is torsionally connected to the valve core 200 through a cross block 2. Specifically, the cross block 2 is a circular plate structure. The front surface and the rear surface of the circular plate are respectively provided with a first keyway 202 and a first key bar 201 along the radial direction; a second key bar 15 is provided at the connection end of the inner switch 1. The cross block 2 and the inner switch 1 are connected through the first keyway 202 and the second key bar 15; a second keyway 16 is provided on the valve core 200. The cross block 2 and the valve core 200 are connected through the second keyway 16 and the first key bar 201.

[0037] It should be noted that the first key bar 201 and the first keyway 202 provided on both sides of the cross block 2 are perpendicular to each other.

[0038] Embodiment 2

[0039] This embodiment discloses a switch mechanism for a cock valve. On the basis of Embodiment 1, in order to prevent the inner switch 1 from rotating excessively during operation, resulting in the re-opening of a closed valve or the re-closing of an opened valve, referring to the attached Figure 3 to the description, a limit ring 6 is further provided in the operation hole 300 of this embodiment. The limit ring 6 is fixed in the operation hole 300 and is used to limit the clockwise rotation angle and the counterclockwise rotation angle of the inner switch 1.

[0040] In the embodiment described in this embodiment, the clockwise rotation and the counterclockwise rotation of the inner switch 1 correspond to the opening and closing of the valve.

[0041] Further, in the embodiment described in this embodiment, the limit of the rotation angle of the inner switch 1 is achieved through the following structural cooperation. Referring to the attached Figure 3-4, the operating end of the inner switch 1 is rotatably arranged in the inner hole of the limiting ring 6. An arc-shaped limiting flange 7 is formed on the end face of the operating end extending along the axial direction of the valve body 100. An arc-shaped limiting protrusion 8 is formed on the end face of the limiting ring 6 extending along the axial direction of the valve body 100. The cooperation between the limiting flange 7 and the limiting protrusion 8 realizes the limitation of the rotation angle of the inner switch 1. Specifically, when the inner switch 1 is externally operated to rotate, the limiting flange 7 rotates synchronously with the inner switch 1. During the rotation process, the limiting flange 7 can selectively abut against one of the side faces of the limiting protrusion 8, thereby restricting the counterclockwise rotation angle or the clockwise rotation angle of the inner switch 1.

[0042] In the above-described structure, in order to improve the sealing effect of the valve, a ring-shaped third sealing member can be provided on the inner wall of the inner hole of the limiting ring 6, and the inner switch 1 and the third sealing member on the inner hole of the limiting ring form a rotational sealing fit relationship.

[0043] Further, in the embodiment depicted in this embodiment, a clamping block 9 is provided on the end face of the limiting ring 6, and a clamping groove 10 is provided on the hole wall of the operation hole 300. The clamping groove 10 is adapted to the shape of the clamping block 9, and the clamping block 9 is clamped in the clamping groove 10 to realize the limitation of the limiting ring 6 and prevent the limiting ring 6 from rotating in the operation hole 300 following the inner switch 1.

[0044] Refer to the attached drawings of the specification Figure 4 , which is a schematic structural diagram of the cooperation and limitation between the limiting ring 6 and the inner switch 1. As shown in the figure, when the limiting flange 7 rotates clockwise with the inner switch 1, when it rotates to abut against the right side face of the limiting protrusion 8, under the blocking action of the limiting protrusion 8, the inner switch 1 cannot continue to rotate. At this time, the clockwise rotation angle of the inner switch 1 is limited. Further, when the limiting flange 7 rotates counterclockwise with the inner switch 1, when it rotates to abut against the left side face of the limiting protrusion 8, under the blocking action of the limiting protrusion 8, the inner switch 1 cannot continue to rotate. At this time, the counterclockwise rotation angle of the inner switch 1 is limited. Furthermore, since the limiting protrusion 8 is provided on the limiting ring 6, in order to simplify the structure of the inner wall of the operation hole 300, the clamping block 9 provided on the limiting ring 6 can be made into an integral structure with the limiting protrusion 8, that is, the limiting protrusion 8 extends axially and lengthens. The limiting protrusion 8 is clamped in the clamping groove 10 and protrudes forward beyond the clamping groove 10. On the one hand, it is used for the limitation of the limiting ring 6 in the operation hole 300, and on the other hand, it cooperates with the limiting flange 7 for the limitation of the inner switch 1.

[0045] Further, in the embodiment depicted in the present embodiment, the internal switch 1 can be decomposed into two components, including a wrench head 101 and a valve stem 102. The wrench head 101 is provided with an internal hexagonal hole penetrating along the radial direction. The valve stem 102 is a hexagonal rod. One end of the valve stem 102 passes through the inner hole of the lining ring 3 and is connected to the internal hexagonal hole on the wrench head 101. The valve stem 102 is rotatably arranged in the inner hole of the lining ring 3 and forms a rotational sealing fit with a second sealing member 5 arranged on the inner hole wall. The other end of the valve stem 102 is connected to the cross block 2 through a transmission block 17. The wrench head 101 is rotatably arranged in the inner hole of the limit ring 6 and forms a rotational sealing fit relationship with a third sealing member arranged on the inner hole wall of the limit ring. Moreover, an arc-shaped limit flange 7 is formed by extending the end face of the wrench head 101 along the axial direction of the valve body 100. The wrench head 101 is connected to an external operating tool such as a wrench. When the wrench head 101 is rotated, the limit flange 7 rotates synchronously with the internal switch 1. During the rotation process, the limit flange 7 can selectively abut against one of the side faces of the limit projection 8, thereby restricting the counterclockwise rotation angle or the clockwise rotation angle of the internal switch 1.

[0046] Refer to the accompanying drawings of the specification Figure 3-4 , the structure of the transmission block 17 is similar to that of the cross block 2, both being a circular plate-like structure. One side of the circular plate is fixedly connected to the valve stem 102, and the other side is provided with a second keyway 15. The transmission block 11 and the cross block 2 are connected through the second keyway 15 and the first keyway 202.

[0047] In the embodiment depicted in the present embodiment, the limit ring, the internal switch, the lining ring, and the cross block together constitute the switching mechanism of the plug valve. Among them, the internal switch is equivalent to the operating end of the entire switching mechanism, and the cross block constitutes the connection end of the entire switching mechanism. During operation, the operating torque received by the wrench head of the internal switch is ultimately transmitted to the valve core through the valve stem, the transmission block, and the cross block, causing the valve core to rotate and realizing the opening and closing of the valve. At the same time, the limit ring restricts the rotation angle of the entire internal switch to 90°, ultimately constraining the valve core channel to be in the correct closed or open position when the valve core rotates to the 0° and 90° positions.

[0048] Embodiment 3

[0049] This embodiment discloses a switching mechanism for a plug valve. On the basis of Embodiment 1, this embodiment further proposes an internal switch structure different from that of Embodiment 2. Refer to the accompanying drawings of the specification Figure 5 and Figure 6, the inner switch 1 has a similar structure to that of a conventional valve stem 1. A convex ring 11 is arranged on the surface of the inner switch 1 along the circumferential direction. An arc-shaped limiting flange 7 is axially extended and formed on the end face of the convex ring 11. A stop post 12 is arranged on the end face of the lining ring 3. The limiting flange 7 rotates synchronously with the inner switch 1 and the limiting flange 7 can selectively abut against one of the faces of the stop post 12 to limit the rotation angles of the inner switch 1 in the counterclockwise and clockwise directions.

[0050] In the implementation mode depicted in the embodiment, the stop post 12 can be a square column, a circular column, or other shapes such as a triangle. The present utility model does not limit the shape of the stop post 12 as long as the limitation of the inner switch 1 can be achieved.

[0051] Further, in this embodiment, during the process of rotating the inner switch 1, since the stop post 12 for limiting the inner switch is directly fixedly arranged on the lining ring 3, if the rotation torque is too large, it may cause the entire lining ring 3 to rotate together with the inner switch, thus losing the limiting function. In this embodiment, a special limiting structure is provided for the lining ring 3 to prevent the lining ring 3 from rotating in the operation hole 300. Refer to the attached Figure 5-6 , a pressing block 13 is arranged in the channel of the valve body. The pressing block 13 is located above the lining ring 3 to press the lining ring 3 to prevent it from rotating. Specifically, the pressing block 13 is fixedly connected to the inner wall of the valve body 100. A convex block 131 is arranged on the pressing block 13. A notch 14 is arranged on the circumference of the lining ring 3. The shape of the notch 14 is adapted to that of the convex block 131. The convex block 131 is inserted into the notch 14 to realize the limitation of the lining ring 3 and prevent it from rotating in the operation hole 300.

[0052] In this embodiment, in order to further reduce the friction force suffered by the inner switch 1 during rotation and achieve a more labor-saving effect, a thrust bearing 18 is further arranged in the operation hole 300. After the operation end of the inner switch 1 passes through the hole of the thrust bearing 18, the convex ring 11 thereon abuts against one side of the thrust bearing 18, and the other side of the thrust shaft 18 abuts against the inner wall of the operation hole 300.

[0053] Embodiment 4

[0054] Based on the same inventive concept, this embodiment proposes a cock valve. Refer to the attached Figure 7As shown, the cock valve includes a valve body 100, a valve core 200, a valve seat 400, and a switching mechanism described in any one of the above embodiments. The valve body 100 has an axially arranged channel inside. Both the valve core 200 and the valve seat 400 are located in the channel. The valve core 200 is supported in the valve body 100 by the valve seat. Further, a circular operation hole 300 is provided on the side wall of the valve body 100. The switching mechanism is rotatably arranged in the operation hole 300 and penetrates into the valve body 100 to be combined with the valve core 200 inside the valve body 100, and is used to manipulate the valve core 200 to rotate, so as to realize the opening and closing of the cock valve.

[0055] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the protection scope of the present invention.

[0056] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0057] The above are only the preferred embodiments of the present invention, and do not constitute any form of limitation to the present invention. Any simple modification and equivalent change made to the above embodiments based on the technical essence of the present invention all fall within the protection scope of the present invention.

Claims

1. A switch mechanism for a plug valve, characterized in that: The switch mechanism is arranged in an operating hole (300) on the side wall of a valve body (100) of the plug valve, and comprises an inner switch (1) and a cross block (2). The inner switch (1) has an operating end and a connecting end. One end of the cross block (2) is connected to the connecting end of the inner switch (1), and the other end is connected to a valve core (200) in the valve body (100). A liner ring (3) is also arranged in the operating hole (300). A first sealing member (4) is arranged between the circumference of the liner ring (3) and the hole wall of the operating hole (300). The connecting end of the inner switch (1) passes through the inner hole of the liner ring (3) and is connected to the cross block (2), and forms a rotating seal with a second sealing member (5) installed on the inner hole of the liner ring (3).

2. A switch mechanism for a plug valve according to claim 1, characterized in that: The switch mechanism also includes a limiting ring (6) fixed in the operating hole (300) and used to limit the rotation angle of the internal switch (1).

3. A switch mechanism for a plug valve according to claim 2, characterized in that: The operating end of the inner switch (1) is rotatably arranged in the inner hole of the limiting ring (6), the end surface of the operating end is axially extended to form an arc-shaped limiting flange (7), and the end surface of the limiting ring (6) is axially extended to form an arc-shaped limiting protrusion (8), the limiting flange (7) rotates synchronously with the inner switch (1) and the limiting flange (7) can selectively abut against one of the surfaces of the limiting protrusion (8) to limit the counterclockwise and clockwise rotation angles of the inner switch (1).

4. A switch mechanism for a plug valve according to claim 2, characterized in that: A clamping block (9) is provided on the end surface of the limiting ring (6), a clamping groove (10) is provided on the hole wall of the operating hole (300), the clamping block (9) and the clamping groove (10) are adapted in shape, and the clamping block (9) is clamped in the clamping groove (10).

5. A switch mechanism for a plug valve according to claim 1, characterized in that: The inner switch (1) has a convex ring (11), the end surface of the convex ring (11) is axially extended to form an arc-shaped limit flange (7), the end surface of the liner ring (3) is provided with a stop column (12), the limit flange (7) rotates synchronously with the inner switch (1) and the limit flange (7) can selectively abut against one of the surfaces of the stop column (12) to limit the counterclockwise and clockwise rotation angles of the inner switch (1).

6. A switch mechanism for a plug valve according to claim 5, characterized in that: A pressure block (13) for limiting the rotation of the liner ring (3) is also provided in the valve body (100) of the plug valve. One end of the pressure block (13) is connected to the inner wall of the valve body, and the other end is provided with a protrusion (131). A recess (14) matching the shape of the protrusion (131) is provided in the circumference of the liner ring (3), and the protrusion (131) is inserted into the recess (14).

7. A switch mechanism for a plug valve according to claim 5, characterized in that: The switch mechanism further comprises a thrust bearing (18) arranged in the operating hole (300); after the other end of the inner switch (1) passes through the thrust bearing (18), the convex ring (11) thereon abuts against one side of the thrust bearing (18), and the other side of the thrust bearing (18) abuts against the inner wall of the operating hole (300).

8. A switch mechanism for a plug valve according to claim 1, characterized in that: The cross block (2) is a circular plate, and first key strips (201) and first key grooves (202) are respectively arranged radially on both sides of the plate. The first key strip (201) is perpendicular to the first key groove (202); the inner switch (1) is provided with a second key strip (15); the cross block (2) is connected to the inner switch (1) via the first key groove (202) and the second key strip (15); the valve core (200) is provided with a second key groove (16); the cross block (2) is connected to the valve core (200) via the second key groove (16) and the first key strip (201).

9. A plug valve, comprising a valve body (100) and a valve core (200), characterized in that: The valve body (100) is mounted with a switch mechanism according to any one of claims 1 to 8, and a connection end of the switch mechanism penetrates into the valve body (100) and is connected to the valve core (200) for operating the valve core (200) to rotate.

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