Buried lengthened flat gate valve

Abstract

The invention relates to the technical field of valves, in particular to a buried lengthened flat gate valve which comprises a valve body, a valve cover is mounted at the upper end of the valve body, and a sectional lengthened valve rod assembly is mounted at the upper end of the valve cover; the lengthened valve rod assembly comprises a first support, a second support and a third support which are installed at the upper end of the valve deck and sequentially connected in a segmented mode, and a first valve rod, a second valve rod and a third valve rod which are sequentially connected in a segmented mode are arranged in the supports. The first valve rod and the second valve rod are connected through a first coupling assembly, and the second valve rod and the third valve rod are connected through a second coupling assembly different from the first coupling assembly. According to the gate valve, the failure of the gate valve caused by bending of the valve rod can be avoided, and the reliability and safety of operation of an underground system pipeline are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of valves, and particularly to a buried extended flat gate valve. Background Art

[0002] At present, for a conventional buried extended gate valve, a whole extended valve stem is adopted. Generally, the opening and closing mode of the gate valve is to drive the upper end of the valve stem to rotate, so as to drive the gate valve to move upward to open the valve. During this working process, the upper end of the valve stem will be subjected to a torsional force, and the rest of the parts will not be stressed. However, due to the too large slenderness ratio of the extended valve stem, the stress concentration at the head of the valve stem will cause an increase in the axial deflection of the valve stem, and further cause the valve stem to bend and deform. In addition, there is also a situation where the operator closes the gate valve with a force far greater than the designed torque during the closing process, which is also likely to cause the valve stem to bend or break, resulting in the failure of the gate valve to work. Since the buried extended flat gate valve is inconvenient to repair and maintain, higher requirements are put forward for its reliability and safety. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the object of the present invention is to provide an extended gate valve that can meet a relatively deep installation height, which can avoid the failure of the gate valve caused by the bending of the valve stem, and improve the reliability and safety of the operation of the underground system pipeline.

[0004] In order to achieve the above invention object, the present invention provides the following technical solutions: A buried extended flat gate valve, the gate valve includes a valve body, a valve cover is installed at the upper end of the valve body, and a segmented extended valve stem assembly is installed at the upper end of the valve cover; Wherein, the extended valve stem assembly includes a first bracket, a second bracket and a third bracket that are installed at the upper end of the valve cover and are sequentially connected in segments, and a first valve stem, a second valve stem and a third valve stem that are sequentially connected in segments are arranged inside the brackets; a first coupling assembly is used to connect between the first valve stem and the second valve stem, and a second coupling assembly different from the first coupling assembly is used to connect between the second valve stem and the third valve stem; A threaded section is provided at the upper end of the first valve stem, the threaded section is in transmission connection with the valve operating end, and a valve plate is connected to the lower end of the third valve stem, and a channel for fluid to flow through is provided on the valve plate.

[0005] Preferably, the first coupling assembly includes a first coupling sleeve sleeved outside the first valve stem and the second valve stem. A plurality of first through holes are provided at both the upper and lower ends of the first coupling sleeve. An annular groove is provided at the lower end of the first valve stem. A first pin shaft is inserted into the annular groove from the first through holes at the upper end to limit the axial movement of the first valve stem and the first coupling sleeve. A first pin shaft hole corresponding to the first through holes is provided at the upper end of the second valve stem. Second pin shafts are respectively inserted into the first through holes at the lower end and the first pin shaft hole to limit the axial movement and circumferential rotation of the second valve stem and the first coupling sleeve.

[0006] Preferably, four first through holes are evenly provided at the upper end of the first coupling sleeve along the circumferential direction. Four first pin shafts are respectively inserted into the annular groove from the four first through holes. Two first pin shaft holes arranged in a crosswise manner along the axial direction are respectively provided at the upper end of the second valve stem. Two second pin shafts are respectively inserted into the corresponding first pin shaft holes.

[0007] Preferably, a first mounting plate is provided at the lower end of the first bracket, a second mounting plate is provided at the upper end of the second bracket, a third mounting plate is provided at the lower end of the second bracket, and a fourth mounting plate is provided at the upper end of the third bracket. A valve stem support structure is provided between the first mounting plate and the second mounting plate, and between the third mounting plate and the fourth mounting plate.

[0008] Preferably, the valve stem support structure is composed of a bearing seat, a sliding bearing, a pressing plate and fasteners. The cross-section of the bearing seat is T-shaped, including a mounting portion and a main body portion connected to the mounting portion. A mounting groove for mounting the sliding bearing is provided on the main body portion. The mounting portion is respectively matched with the second mounting plate or the fourth mounting plate and is installed on the second mounting plate or the fourth mounting plate through the fasteners. The sliding bearing made of PTFE material is installed in the mounting groove. The pressing plate is installed on the mounting portion above the sliding bearing through the fasteners.

[0009] Preferably, a fifth positioning portion is provided on the bearing seat. A first positioning portion and a second positioning portion are respectively provided on the first mounting plate and the second mounting plate. The fifth positioning portion is respectively matched with the first positioning portion and the second positioning portion to realize the installation and positioning of the upper bearing seat. A third positioning portion is respectively provided on the third mounting plate and the fourth mounting plate. The third mounting plate and the fourth mounting plate are installed and positioned through the cooperation of the third positioning portions. A fourth positioning portion is provided on the fourth mounting plate. The fifth positioning portion is matched with the fourth positioning portion to realize the installation and positioning of the lower bearing seat.

[0010] Preferably, the second coupling assembly includes a second coupling sleeve sleeved outside the second valve stem and the third valve stem. A plurality of second through holes are provided at both the upper and lower ends of the second coupling sleeve. Second pin holes corresponding to the second through holes are respectively provided at the ends of the second valve stem and the third valve stem. Third pins are respectively inserted into the second through holes and the second pin holes at the upper end to limit the axial movement and circumferential rotation of the second valve stem and the second coupling sleeve. Fourth pins are respectively inserted into the second through holes and the second pin holes at the lower end to limit the axial movement and circumferential rotation of the third valve stem and the second coupling sleeve.

[0011] Preferably, two second pin holes arranged in a crosswise and staggered manner along the axial direction are respectively provided at the ends of the second valve stem and the third valve stem. The third pin and the fourth pin are respectively inserted into the corresponding two second pin holes.

[0012] Preferably, the second coupling assembly includes a coupling sleeve sleeved outside the second valve stem and the third valve stem and formed by splicing a first half-coupling sleeve and a second half-coupling sleeve. A first elastic groove is provided in the middle of the first half-coupling sleeve, and a second elastic groove is provided in the middle of the second half-coupling sleeve. When the first half-coupling sleeve and the second half-coupling sleeve are spliced into a complete coupling sleeve, the first elastic groove and the second elastic groove are symmetrically arranged with respect to the connection between the second valve stem and the third valve stem, and the distance between the two elastic grooves corresponding to the connection between the second valve stem and the third valve stem is greater than the distance between the two elastic grooves at other positions.

[0013] Preferably, third through holes are respectively provided at the upper and lower ends of the first half-coupling sleeve and the second half-coupling sleeve. Pin holes corresponding to the third through holes are respectively provided at the ends of the second valve stem and the third valve stem. A fixing ring is sleeved outside the first half-coupling sleeve and the second half-coupling sleeve. A fifth pin sequentially passes through the fixing ring, the third through hole and the pin hole to connect the first half-coupling sleeve and the second half-coupling sleeve with the valve stem.

[0014] Compared with the prior art, a buried extended flat gate valve provided by the present invention has the following beneficial technical effects: 1. Since the valve stem structure of the present invention is segmented, the slenderness ratio of the valve stem is reduced. At the same time, a first coupling assembly is used to connect the first valve stem and the second valve stem. The first coupling assembly can limit the axial movement of the first valve stem and the first coupling sleeve, as well as the axial movement and circumferential rotation of the second valve stem and the first coupling sleeve. Since the first coupling assembly does not limit the circumferential movement of the first valve stem, when the operating end of the valve is operated to drive the first valve stem to rotate, the torsional forces borne by the second valve stem and the third valve stem are significantly reduced, thereby reducing the probability of the gate valve failing due to excessive torsional force on the valve stem, and improving the reliability and safety of the pipeline operation in the underground system.

[0015] 2. In the present invention, since valve stem support structures are provided between the first mounting plate and the second mounting plate, and between the third mounting plate and the fourth mounting plate, this structure can support the valve stem and avoid the defect of increased coaxiality caused by the lengthened valve stem. At the same time, the sliding bearing made of PTFE material can reduce the friction coefficient of the valve stem, lubricate the valve stem, and reduce the operating torque of the valve. At the same time, by respectively providing positioning parts on the mounting plate and the bearing seat, the coaxiality of the lengthened valve stem can be improved, further reducing the friction force during the up and down movement of the valve stem and reducing the operating torque of the valve.

[0016] 3. The present invention is provided with elastic grooves symmetric about the connection of the second valve stem and the third valve stem in the middle of the first half coupling sleeve and the second half coupling sleeve, so that when the valve stem undergoes elastic bending deformation, the second coupling assembly can correspondingly produce elastic deformation, reducing the probability of the coupling assembly failing (being damaged). Secondly, since the first half coupling sleeve and the second half coupling sleeve are spliced to form a coupling sleeve, when an extreme situation occurs, that is, the coupling assembly is damaged, the above structure can conveniently and quickly replace the damaged part of the coupling assembly. Furthermore, since the second coupling assembly is subjected to a large bending moment at the connection of the second valve stem and the third valve stem, the distance between the elastic grooves on both sides corresponding to the connection of the second valve stem and the third valve stem is greater than the distance between the two elastic grooves at other positions, which can enhance the structural strength of the corresponding part of the second coupling assembly without affecting the overall elastic deformation ability and avoid the second coupling assembly from being damaged. In addition, the inventor found that the coupling assembly that fails is often the second coupling assembly rather than the first coupling assembly, so a structure similar to the second coupling assembly in Embodiment 2 is not provided on the first coupling assembly. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the overall structure of a buried extended flat gate valve; Figure 2 is Figure 1 a partial enlarged view of part A in Figure 3 is Figure 1 a partial enlarged view of part B in Figure 4 It is a schematic structural diagram of a bearing seat; Figure 5 It is a schematic diagram of another embodiment of the second coupling assembly.

[0018] Among them, the meanings of the reference symbols in the figure are as follows: 1. Valve body; 2. Valve cover; 3. First valve stem; 4. Second valve stem; 5. Third valve stem; 6. First bracket; 7. Second bracket; 8. Third bracket; 9. Valve plate; 11. First mounting plate; 12. Second mounting plate; 13. First positioning portion; 14. Second positioning portion; 20. First coupling sleeve; 21. Annular groove; 22. First through hole; 23. First pin shaft hole; 24. First pin shaft; 25. Second pin shaft; 30. Second coupling sleeve; 31. Second through hole; 32. Second pin shaft hole; 33. Third pin shaft; 34. Fourth pin shaft; 41. Third mounting plate; 42. Fourth mounting plate; 43. Bearing seat; 44. Sliding bearing; 45. Pressure plate; 46. Third positioning portion; 47. Fourth positioning portion; 431. Mounting portion; 432. Main body portion; 433. Mounting groove; 434. Fifth positioning portion; 51. First half coupling sleeve; 52. Second half coupling sleeve; 53. First elastic groove; 54. Second elastic groove; 55. Third through hole; 56. Fifth pin shaft; 57. Fixed ring. Specific embodiments

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0020] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents some embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0021] It should be noted that, without conflict, the embodiments in the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0022] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0023] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is customarily placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. Such terms are 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, and therefore should not be construed as a limitation on the present invention. In addition, terms such as "first" and "second" are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0024] See the attached Figure 1 - attached Figure 5 As shown, the present invention provides a buried extended flat gate valve, which includes a valve body 1. A valve cover 2 is installed at the upper end of the valve body 1, and a segmented extended valve stem assembly is installed at the upper end of the valve cover 2. A ground operation accessory is also provided outside the gate valve. Among them, the extended valve stem assembly includes a first bracket 6, a second bracket 7, and a third bracket 8 that are installed at the upper end of the valve cover 2 and are sequentially connected in segments. Inside several brackets, a first valve stem 3, a second valve stem 4, and a third valve stem 5 are sequentially connected in segments. Among them, a first coupling assembly is used to connect the first valve stem 3 and the second valve stem 4, and a second coupling assembly different from the first coupling assembly is used to connect the second valve stem 4 and the third valve stem 5; a threaded section is provided at the upper end of the first valve stem 3, and this threaded section is in transmission connection with the valve operation end. The lower end of the third valve stem 5 is connected to a valve plate 9, and a channel for fluid flow is provided on the valve plate 9. In this embodiment, the extended valve stem assembly is composed of a three-section valve stem and a bracket structure. Each section of the valve stem has undergone stability calculations. By using a three-section valve stem without increasing the diameter of the valve stem, the requirements for the stability of the valve stem are met. Of course, the extended valve stem assembly can also be composed of other numbers of valve stems and bracket structures according to needs, but preferably a three-section structure is adopted.

[0025] Preferably, the first coupling assembly includes a first coupling sleeve 20 sleeved outside the first valve stem 3 and the second valve stem 4. A plurality of first through holes 22 are provided at both the upper and lower ends of the first coupling sleeve 20. An annular groove 21 is provided at the lower end of the first valve stem 3. A first pin shaft 24 is inserted from the upper first through hole 22 into the annular groove 21 to limit the axial movement of the first valve stem 3 and the first coupling sleeve 20; a first pin shaft hole 23 corresponding to the first through hole 22 is provided at the upper end of the second valve stem 4, and a second pin shaft 25 is respectively inserted into the lower first through hole 22 and the first pin shaft hole 23 to limit the axial movement and circumferential rotation of the second valve stem 4 and the first coupling sleeve 20.

[0026] Preferably, four first through holes 22 are evenly formed in the upper end of the first coupling sleeve 20 in the circumferential direction, and four first pin shafts 24 are respectively inserted into the annular groove 21 from the four first through holes 22; two first pin holes 23 which are arranged in a crosswise manner are axially formed in the upper end of the second valve stem 4, and two second pin shafts 25 are respectively inserted into the corresponding first pin holes 23.

[0027] In the above embodiment, due to the adoption of the segmented valve stem structure, the slenderness ratio of the valve stem is reduced. At the same time, a first coupling assembly is used to connect the first valve stem and the second valve stem. The first coupling assembly can limit the axial movement of the first valve stem and the first coupling sleeve, and limit the axial movement and circumferential rotation of the second valve stem and the first coupling sleeve. Since the first coupling assembly does not limit the circumferential movement of the first valve stem, when the valve operating end is operated to drive the first valve stem to rotate, the torsional forces borne by the second valve stem and the third valve stem are significantly reduced, thereby reducing the probability of the gate valve failure caused by excessive torsional force on the valve stem, and improving the reliability and safety of the underground system pipeline operation.

[0028] Preferably, a first mounting plate 11 is arranged at the lower end of the first bracket 6, a second mounting plate 12 is arranged at the upper end of the second bracket 7, a third mounting plate 41 is arranged at the lower end of the second bracket 7, a fourth mounting plate 42 is arranged at the upper end of the third bracket 8, and valve stem support structures are arranged between the first mounting plate 11 and the second mounting plate 12, and between the third mounting plate 41 and the fourth mounting plate 42.

[0029] The valve stem support structure is composed of a bearing seat 43, a sliding bearing 44, a pressing plate 45 and fasteners. The cross section of the bearing seat 43 is generally T-shaped, including a mounting portion 431 and a main body portion 432 connected to the mounting portion 431. An installation groove 433 for installing the sliding bearing 44 is formed in the main body portion 432; the mounting portion 431 is respectively matched with the second mounting plate 12 or the fourth mounting plate 42, and is installed on the second mounting plate 12 or the fourth mounting plate 42 through fasteners. The sliding bearing 44 made of PTFE material is installed in the installation groove 433, and the pressing plate 45 is installed on the mounting portion 431 through fasteners above the sliding bearing 44 to prevent the sliding bearing from being taken out of the bearing seat due to the friction generated when the valve stem moves up and down.

[0030] In the above preferred embodiment, valve stem support structures are arranged between the first mounting plate and the second mounting plate, and between the third mounting plate and the fourth mounting plate. This structure can support the valve stem and avoid the defect of increased coaxiality caused by the lengthened valve stem. At the same time, the sliding bearing made of PTFE material can reduce the friction coefficient of the valve stem, lubricate the valve stem, and reduce the valve operating torque.

[0031] Preferably, a fifth positioning portion 434 is provided on the bearing seat 43, and a first positioning portion 13 and a second positioning portion 14 are respectively provided on the first mounting plate 11 and the second mounting plate 12. The fifth positioning portion 434 cooperates with the first positioning portion 13 and the second positioning portion 14 respectively to realize the installation and positioning of the upper bearing seat 43; third positioning portions 46 are respectively provided on the third mounting plate 41 and the fourth mounting plate 42. The third mounting plate 41 and the fourth mounting plate 42 are installed and positioned through the cooperation of the third positioning portions 46. A fourth positioning portion 47 is provided on the fourth mounting plate 42. The fifth positioning portion 434 cooperates with the fourth positioning portion 47 to realize the installation and positioning of the lower bearing seat 43.

[0032] According to the above preferred embodiment, by respectively providing positioning portions on the mounting plate and the bearing seat, the coaxiality of the lengthened valve stem can be improved, the friction force of the valve stem during the up and down movement can be further reduced, and the valve operating torque can be reduced.

[0033] In the present invention, the second coupling assembly adopts one of the following two embodiments, wherein, Embodiment 1: Preferably, the second coupling assembly includes a second coupling sleeve 30 sleeved outside the second valve stem 4 and the third valve stem 5. A plurality of second through holes 31 are opened at both the upper and lower ends of the second coupling sleeve 30. Second pin holes 32 corresponding to the second through holes 31 are respectively opened at the ends of the second valve stem 4 and the third valve stem 5. The third pin 33 is respectively inserted into the second through hole 31 and the second pin hole 32 at the upper end to limit the axial movement and circumferential rotation of the second valve stem 4 and the second coupling sleeve 30. The fourth pin 34 is respectively inserted into the second through hole 31 and the second pin hole 32 at the lower end to limit the axial movement and circumferential rotation of the third valve stem 5 and the second coupling sleeve 30.

[0034] Preferably, two second pin holes 32 arranged in a crosswise manner are respectively axially opened at the ends of the second valve stem 4 and the third valve stem 5. The third pin 33 and the fourth pin 34 are respectively inserted into the corresponding two second pin holes 32.

[0035] Embodiment 2: During the use of the gate valve, the inventor found that due to improper operation of the operator (for example, continuing to push the first valve stem 3 to drive the second valve stem 4 and the third valve stem 5 to move downward after the gate valve is closed), it is easy to cause bending deformation between the first valve stem 3, the second valve stem 4 and the third valve stem 5, and further cause the loosening and falling off of the connecting parts (such as pins) between the valve stem and the coupling assembly, resulting in the failure of the coupling assembly. In severe cases, it may even cause damage to the coupling. In addition, the inventor found that the failed coupling assembly is often the second coupling assembly rather than the first coupling assembly. Therefore, the second coupling assembly in Embodiment 1 is improved to form the following preferred embodiment.

[0036] The second coupling assembly includes a coupling sleeve sleeved outside the second valve stem 4 and the third valve stem 5 and formed by splicing a first half coupling sleeve 51 and a second half coupling sleeve 52; a first elastic groove 53 is formed in the middle of the first half coupling sleeve 51, and a second elastic groove 54 is formed in the middle of the second half coupling sleeve 52. When the first half coupling sleeve 51 and the second half coupling sleeve 52 are spliced into a complete coupling sleeve, the first elastic groove 53 and the second elastic groove 54 are symmetrically arranged about the connection of the second valve stem 4 and the third valve stem 5, and the distance between the two elastic grooves corresponding to the connection of the second valve stem 4 and the third valve stem 5 is greater than the distance between the two elastic grooves at other positions. Third through holes 55 are respectively formed at the upper and lower ends of the first half coupling sleeve 51 and the second half coupling sleeve 52, pin holes corresponding to the third through holes 55 are respectively formed at the ends of the second valve stem 4 and the third valve stem 5, and a fixing ring 57 is sleeved outside the first half coupling sleeve 51 and the second half coupling sleeve 52. A fifth pin shaft 56 sequentially passes through the fixing ring 57, the third through holes 55 and the pin holes to connect the first half coupling sleeve 51 and the second half coupling sleeve 52 with the valve stem.

[0037] In the above preferred embodiment, elastic grooves symmetric about the connection of the second valve stem and the third valve stem are provided in the middle of the first half coupling sleeve and the second half coupling sleeve, so that when the valve stem undergoes elastic bending deformation, the second coupling assembly can correspondingly generate elastic deformation, reducing the probability of failure (damage) of the coupling assembly. Secondly, since the coupling sleeve is formed by splicing the first half coupling sleeve and the second half coupling sleeve, when an extreme situation occurs, that is, the coupling assembly is damaged, the above structure can conveniently and quickly replace the damaged part of the coupling assembly. Moreover, since the second coupling assembly is subjected to a large bending moment at the connection of the second valve stem and the third valve stem, the distance between the two elastic grooves on both sides corresponding to the connection of the second valve stem and the third valve stem is greater than the distance between the two elastic grooves at other positions, which can enhance the structural strength of the corresponding part of the second coupling assembly without affecting the overall elastic deformation ability and avoid damage to the second coupling assembly. In addition, the inventor found that the coupling assembly that fails is often the second coupling assembly rather than the first coupling assembly, so a structure similar to that of the second coupling assembly in the second embodiment is not provided on the first coupling assembly.

[0038] The above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention. Although this specification has described the present invention in detail with reference to the above respective embodiments, the present invention is not limited to the above specific embodiments. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the invention are covered by the scope of the claims of the present invention.

Claims

1. An underground extended flat gate valve, characterized in that: The gate valve includes a valve body, a valve cover is installed at the upper end of the valve body, and a segmented extended valve stem assembly is installed at the upper end of the valve cover; Among them, the extended valve stem assembly includes a first bracket, a second bracket and a third bracket that are installed at the upper end of the valve cover and are sequentially connected in segments. A first valve stem, a second valve stem and a third valve stem that are sequentially connected in segments are arranged inside the brackets; a first coupling assembly is used to connect between the first valve stem and the second valve stem, and a second coupling assembly different from the first coupling assembly is used to connect between the second valve stem and the third valve stem; A threaded section is arranged at the upper end of the first valve stem, and the threaded section is in transmission connection with the valve operation end. A valve plate is connected to the lower end of the third valve stem, and a channel for fluid to flow through is opened on the valve plate.

2. The slab gate valve according to claim 1, characterized in that: The first coupling assembly includes a first coupling sleeve sleeved outside the first valve stem and the second valve stem. A plurality of first through holes are opened at both the upper and lower ends of the first coupling sleeve. An annular groove is opened at the lower end of the first valve stem. A first pin shaft is inserted into the annular groove from the upper first through hole to limit the axial movement of the first valve stem and the first coupling sleeve; a first pin shaft hole corresponding to the first through hole is opened at the upper end of the second valve stem, and second pin shafts are respectively inserted into the lower first through hole and the first pin shaft hole to limit the axial movement and circumferential rotation of the second valve stem and the first coupling sleeve.

3. The slab gate valve according to claim 2, characterized in that: Four first through holes are evenly opened along the circumferential direction at the upper end of the first coupling sleeve, and four first pin shafts are respectively inserted into the annular groove from the four first through holes; two first pin shaft holes arranged in a crosswise manner are respectively opened along the axial direction at the upper end of the second valve stem, and two second pin shafts are respectively inserted into the corresponding first pin shaft holes.

4. The slab gate valve according to claim 3, wherein: A first mounting plate is arranged at the lower end of the first bracket, a second mounting plate is arranged at the upper end of the second bracket, a third mounting plate is arranged at the lower end of the second bracket, and a fourth mounting plate is arranged at the upper end of the third bracket. A valve stem support structure is arranged between the first mounting plate and the second mounting plate, and between the third mounting plate and the fourth mounting plate.

5. The flat gate valve according to claim 4, characterized in that: The valve stem support structure is composed of a bearing seat, a sliding bearing, a pressing plate and fasteners. The cross section of the bearing seat is T-shaped, including a mounting portion and a main body portion connected to the mounting portion. A mounting groove for mounting the sliding bearing is opened on the main body portion; the mounting portion is respectively matched with the second mounting plate or the fourth mounting plate and is installed on the second mounting plate or the fourth mounting plate through the fasteners. The sliding bearing made of PTFE material is installed in the mounting groove, and the pressing plate is installed on the mounting portion above the sliding bearing through the fasteners.

6. The slab gate valve according to claim 5, wherein: A fifth positioning portion is provided on the bearing seat, and a first positioning portion and a second positioning portion are respectively provided on the first mounting plate and the second mounting plate. The fifth positioning portion cooperates with the first positioning portion and the second positioning portion respectively to achieve the installation and positioning of the upper bearing seat; a third positioning portion is respectively provided on the third mounting plate and the fourth mounting plate. The third mounting plate and the fourth mounting plate are installed and positioned through the cooperation of the third positioning portions. A fourth positioning portion is provided on the fourth mounting plate. The fifth positioning portion cooperates with the fourth positioning portion to achieve the installation and positioning of the lower bearing seat.

7. The slab gate valve according to claim 6, wherein: The second coupling assembly includes a second coupling sleeve sleeved outside the second valve stem and the third valve stem. A plurality of second through holes are provided at both the upper and lower ends of the second coupling sleeve. Second pin holes corresponding to the second through holes are respectively provided at the ends of the second valve stem and the third valve stem. Third pins are respectively inserted into the second through holes and the second pin holes at the upper end to limit the axial movement and circumferential rotation of the second valve stem and the second coupling sleeve. Fourth pins are respectively inserted into the second through holes and the second pin holes at the lower end to limit the axial movement and circumferential rotation of the third valve stem and the second coupling sleeve.

8. The slab gate valve according to claim 7, characterized in that: Two second pin holes arranged in a crosswise manner are respectively provided at the ends of the second valve stem and the third valve stem along the axial direction. The third pin and the fourth pin are respectively inserted into the corresponding two second pin holes.

9. The slab gate valve according to claim 6, characterized in that: The second coupling assembly includes a coupling sleeve sleeved outside the second valve stem and the third valve stem and formed by splicing a first half-coupling sleeve and a second half-coupling sleeve; a first elastic groove is provided in the middle of the first half-coupling sleeve, and a second elastic groove is provided in the middle of the second half-coupling sleeve. When the first half-coupling sleeve and the second half-coupling sleeve are spliced into a complete coupling sleeve, the first elastic groove and the second elastic groove are symmetrically arranged with respect to the connection of the second valve stem and the third valve stem, and the distance between the two elastic grooves corresponding to the connection of the second valve stem and the third valve stem is greater than the distance between the two elastic grooves at other positions.

10. The slab gate valve according to claim 9, characterized in that: Third through holes are respectively provided at the upper and lower ends of the first half-coupling sleeve and the second half-coupling sleeve. Pin holes corresponding to the third through holes are respectively provided at the ends of the second valve stem and the third valve stem. A fixing ring is sleeved outside the first half-coupling sleeve and the second half-coupling sleeve. A fifth pin sequentially passes through the fixing ring, the third through hole and the pin hole to connect the first half-coupling sleeve and the second half-coupling sleeve with the valve stem.

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