A buried extended flat gate valve

Abstract

The present invention relates to the field of valve technology, and more specifically, to an underground extended flat gate valve, comprising a valve body, a valve cover mounted on the upper end of the valve body, and a segmented extended valve stem assembly mounted on the upper end of the valve cover. The extended valve stem assembly comprises a first bracket, a second bracket, and a third bracket mounted on the upper end of the valve cover and connected in sequence in segments. A first valve stem, a second valve stem, and a third valve stem are disposed within the brackets and connected in sequence in segments. The first valve stem and the second valve stem are connected by a first coupling assembly, and the second valve stem and the third valve stem are connected by a second coupling assembly, which is different from the first coupling assembly. This gate valve can avoid gate valve failure caused by valve stem bending, thereby improving the reliability and safety of underground system pipeline operations.

Description

Technical Field

[0001] The present invention relates to the technical field of valves, and in particular to an underground extended flat gate valve. Background Art

[0002] Conventional buried extended gate valves utilize a single, extended stem. They typically open and close by rotating the upper end of the stem, which in turn moves the valve upward to open the valve. During this operation, the upper end of the stem is subjected to torsional forces, while the rest of the stem is unstressed. However, due to the extended stem's excessive slenderness, stress concentration at the stem head increases axial deflection, leading to stem bending and deformation. Furthermore, operators may apply forces far exceeding the designed torque when closing the gate valve, which can easily cause the stem to bend or break, resulting in valve failure. Due to the inconvenience of repairing and maintaining buried extended flat gate valves, higher standards for reliability and safety are being placed on them. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide an extended gate valve that can meet the requirements of a deeper installation height. The gate valve can avoid gate valve failure caused by valve stem bending, thereby improving the reliability and safety of underground system pipeline operation.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] A buried extended flat gate valve, comprising a valve body, a valve cover mounted on the upper end of the valve body, and a segmented extended valve stem assembly mounted on the upper end of the valve cover;

[0006] The extended valve stem assembly includes a first bracket, a second bracket, and a third bracket mounted on the upper end of the valve cover and connected in sections in sequence. The first valve stem, the second valve stem, and the third valve stem are disposed inside the bracket and connected in sections in sequence. The first valve stem and the second valve stem are connected by a first coupling assembly, and the second valve stem and the third valve stem are connected by a second coupling assembly different from the first coupling assembly.

[0007] The upper end of the first valve stem is provided with a threaded section, which is transmission-connected to the valve operating end. The lower end of the third valve stem is connected to a valve plate, which has a channel for fluid circulation.

[0008] Preferably, the first coupling assembly includes a first coupling sleeve that is sleeved on the outside of the first valve stem and the second valve stem, and a plurality of first through holes are provided at the upper and lower ends of the first coupling sleeve. The lower end of the first valve stem is provided with an annular groove, and a first pin is inserted from the first through hole at the upper end into the annular groove to limit the axial movement of the first valve stem and the first coupling sleeve; the upper end of the second valve stem is provided with a first pin hole corresponding to the first through hole, and the second pin is respectively inserted into the first through hole and the first pin hole at the lower end to limit the axial movement and circumferential rotation of the second valve stem and the first coupling sleeve.

[0009] Preferably, four first through holes are evenly opened at the upper end of the first coupling sleeve along the circumferential direction, and the four first pins are respectively inserted into the annular groove from the four first through holes; two first pin holes are respectively opened at the upper end of the second valve stem along the axial direction and arranged in a cross pattern, and the two second pins are respectively inserted into the corresponding first pin holes.

[0010] 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, a fourth mounting plate is provided at the upper end of the third bracket, and 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.

[0011] Preferably, the valve stem supporting structure consists of a bearing seat, a sliding bearing, a pressure plate and a fastener. The cross-section of the bearing seat is T-shaped, including a mounting portion and a main body connected to the mounting portion, and the main body is provided with a mounting groove for installing the sliding bearing; the mounting portion cooperates with the second mounting plate or the fourth mounting plate respectively, and is installed to the second mounting plate or the fourth mounting plate through the fastener, the sliding bearing made of PTFE material is installed in the mounting groove, and the pressure plate is installed on the mounting portion above the sliding bearing through the fastener.

[0012] Preferably, a fifth positioning portion is provided on the bearing seat, and a first positioning portion and a second positioning portion are provided on the first mounting plate and the second mounting plate respectively, and the fifth positioning portion cooperates with the first positioning portion and the second positioning portion respectively to realize the installation and positioning of the upper end bearing seat; a third positioning portion is provided on the third mounting plate and the fourth mounting plate respectively, and the third mounting plate and the fourth mounting plate are installed and positioned by cooperating with the third positioning portion, and a fourth positioning portion is provided on the fourth mounting plate, and the fifth positioning portion cooperates with the fourth positioning portion to realize the installation and positioning of the lower end bearing seat.

[0013] Preferably, the second coupling assembly includes a second coupling sleeve that is sleeved on the outside of the second valve stem and the third valve stem, and a plurality of second through holes are provided at the upper and lower ends of the second coupling sleeve. The ends of the second valve stem and the third valve stem are also respectively provided with second pin holes corresponding to the second through holes, and the third pin is respectively inserted into the second through hole and the second pin hole at the upper end to limit the axial movement and circumferential rotation of the second valve stem and the second coupling sleeve, and the fourth pin is respectively inserted into the second through hole and the second pin hole at the lower end to limit the axial movement and circumferential rotation of the third valve stem and the second coupling sleeve.

[0014] Preferably, two second pin shaft holes arranged in a cross-like manner are respectively opened at the ends of the second valve stem and the third valve stem along the axial direction, and the third pin shaft and the fourth pin shaft are respectively inserted into the corresponding two second pin shaft holes.

[0015] Preferably, the second coupling assembly includes a coupling sleeve which is sleeved on the outside of the second valve stem and the third valve stem and is formed by splicing a first half coupling sleeve and a second half coupling sleeve; a first elastic groove is opened in the middle of the first half coupling sleeve, and a second elastic groove is opened 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 about 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.

[0016] 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, and pin holes corresponding to the third through holes are respectively provided at the ends of the second valve stem and the third valve stem, and fixing rings are sleeved on the outside of the first half coupling sleeve and the second half coupling sleeve, and a fifth pin passes through the fixing ring, the third through hole and the pin hole in sequence to connect the first half coupling sleeve and the second half coupling sleeve to the valve stem.

[0017] Compared with the prior art, the buried extended flat gate valve provided by the present invention has the following beneficial technical effects:

[0018] 1. The present invention utilizes a segmented valve stem structure, thereby reducing the slenderness ratio of the valve stem. Furthermore, a first coupling assembly is employed to connect the first and second valve stems. The first coupling assembly limits axial movement of the first valve stem and the first coupling sleeve, as well as axial movement and circumferential rotation of the second valve stem and the first coupling sleeve. Because the first coupling assembly does not restrict the circumferential movement of the first valve stem, when the valve operating end drives the first valve stem to rotate, the torsional force experienced by the second and third valve stems is significantly reduced. This, in turn, reduces the probability of gate valve failure due to excessive torsional force on the valve stem, thereby improving the reliability and safety of underground system pipeline operations.

[0019] 2. In the present invention, the valve stem support structure provided between the first and second mounting plates, as well as between the third and fourth mounting plates, supports the valve stem, preventing the defect of increased coaxiality caused by an extended valve stem. Furthermore, the PTFE sliding bearing reduces the valve stem friction coefficient, lubricates the valve stem, and reduces valve operating torque. Furthermore, by providing positioning portions on the mounting plate and bearing seat, the coaxiality of the extended valve stem is improved, further reducing friction during the vertical movement of the valve stem and the valve operating torque.

[0020] 3. The present invention provides elastic grooves symmetrically positioned about the junction between the second and third valve stems in the middle portions of the first and second coupling sleeve halves. This allows the second coupling assembly to elastically deform when the valve stems undergo elastic bending deformation, thereby reducing the probability of coupling assembly failure (damage). Furthermore, because the coupling sleeve is formed by splicing the first and second coupling sleeve halves together, in the event of coupling assembly damage, this structure allows for convenient and rapid replacement of the damaged portion of the coupling assembly. Furthermore, because the second coupling assembly is subject to significant bending moment at the junction between the second and third valve stems, the distance between the elastic grooves corresponding to the junction between the second and third valve stems is greater than the distance between the elastic grooves at other locations. This enhances the structural strength of the corresponding portion of the second coupling assembly without compromising its overall elastic deformation capacity, thus preventing damage to the second coupling assembly. Furthermore, the inventors have discovered that coupling assembly failure often occurs in the second coupling assembly, not the first. Therefore, the first coupling assembly is not equipped with a structure similar to that described in Example 2. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the overall structure of the buried extended flat gate valve;

[0022] Figure 2 for Figure 1 A partial enlarged schematic diagram of point A in the middle;

[0023] Figure 3 for Figure 1 A partial enlarged schematic diagram of point B in the middle;

[0024] Figure 4 It is a structural diagram of the bearing seat;

[0025] Figure 5 Schematic diagram of another embodiment of the second coupling assembly.

[0026] The meanings of the symbols in the figure are as follows:

[0027] 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;

[0028] 11. First mounting plate; 12. Second mounting plate; 13. First positioning portion; 14. Second positioning portion;

[0029] 20. First coupling sleeve; 21. Annular groove; 22. First through hole; 23. First pin hole; 24. First pin; 25. Second pin;

[0030] 30. Second coupling sleeve; 31. Second through hole; 32. Second pin hole; 33. Third pin; 34. Fourth pin;

[0031] 41. Third mounting plate; 42. Fourth mounting plate; 43. Bearing seat; 44. Sliding bearing; 45. Pressing plate; 46. Third positioning portion; 47. Fourth positioning portion;

[0032] 431, mounting portion; 432, main body; 433, mounting groove; 434, fifth positioning portion;

[0033] 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; 57. Fixed ring. DETAILED DESCRIPTION

[0034] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, 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 only part of the embodiments of the present invention, not all of them.

[0035] 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 derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions therein may be combined with each other.

[0037] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0038] In the description of the present invention, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is typically placed when in use, or the orientations or positional relationships commonly understood by those skilled in the art. Such terms are intended solely to facilitate the description of the present invention and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" and the like are used solely for distinction and should not be construed as indicating or implying relative importance.

[0039] See attached Figure 1 -Attached Figure 5 As shown, the present invention provides an underground extended flat gate valve, which includes a valve body 1, a valve cover 2 mounted on the upper end of the valve body 1, a segmented extended valve stem assembly mounted on the upper end of the valve cover 2, and a ground operating accessory disposed on the outside of the gate valve. The extended valve stem assembly includes a first bracket 6, a second bracket 7, and a third bracket 8 mounted on the upper end of the valve cover 2 and connected in sections in sequence. A first valve stem 3, a second valve stem 4, and a third valve stem 5 are disposed within the brackets and connected in sections in sequence. The first valve stem 3 and the second valve stem 4 are connected by a first coupling assembly, while the second valve stem 4 and the third valve stem 5 are connected by a second coupling assembly different from the first coupling assembly. A threaded section is disposed on the upper end of the first valve stem 3, which is in transmission connection with the valve operating end. The lower end of the third valve stem 5 is connected to a valve plate 9, which has a passage for fluid circulation. In this embodiment, the extended valve stem assembly consists of a three-section valve stem and a bracket structure. Each valve stem section has undergone stability calculations. The three-section valve stem meets valve stem stability requirements without increasing the valve stem diameter. While the extended valve stem assembly can also utilize other valve stem sections and bracket structures as needed, a three-section structure is preferred.

[0040] Preferably, the first coupling assembly includes a first coupling sleeve 20 which is sleeved on the outside of the first valve stem 3 and the second valve stem 4, and a plurality of first through holes 22 are provided at the upper and lower ends of the first coupling sleeve 20. The lower end of the first valve stem 3 is provided with an annular groove 21, and the first pin 24 is inserted into the annular groove 21 from the first through hole 22 at the upper end to limit the axial movement of the first valve stem 3 and the first coupling sleeve 20; the upper end of the second valve stem 4 is provided with a first pin hole 23 corresponding to the first through hole 22, and the second pin 25 is respectively inserted into the first through hole 22 and the first pin hole 23 at the lower end to limit the axial movement and circumferential rotation of the second valve stem 4 and the first coupling sleeve 20.

[0041] Preferably, four first through holes 22 are evenly opened in the circumferential direction at the upper end of the first coupling sleeve 20, and four first pins 24 are respectively inserted into the annular groove 21 from the four first through holes 22; two first pin holes 23 are respectively opened in the axial direction at the upper end of the second valve stem 4 in a cross-staggered arrangement, and two second pins 25 are respectively inserted into the corresponding first pin holes 23.

[0042] In the above embodiment, due to the use of a 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, as well as the axial movement and circumferential rotation of the second valve stem and the first coupling sleeve. Because the first coupling assembly does not limit the circumferential movement of the first valve stem, when the valve operating end drives the first valve stem to rotate, the torsional force exerted on the second and third valve stems is significantly reduced, thereby reducing the probability of gate valve failure due to excessive torsional force on the valve stem, thereby improving the reliability and safety of underground system pipeline operation.

[0043] Preferably, a first mounting plate 11 is provided at the lower end of the first bracket 6, a second mounting plate 12 is provided at the upper end of the second bracket 7, a third mounting plate 41 is provided at the lower end of the second bracket 7, and a fourth mounting plate 42 is provided at the upper end of the third bracket 8. Valve stem support structures are provided 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.

[0044] Among them, the valve stem support structure consists of a bearing seat 43, a sliding bearing 44, a pressure plate 45 and fasteners. The cross-section of the bearing seat 43 is roughly T-shaped, including a mounting portion 431 and a main body 432 connected to the mounting portion 431. The main body 432 is provided with a mounting groove 433 for installing the sliding bearing 44; the mounting portion 431 is respectively cooperated 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 mounting groove 433, and the pressure plate 45 is installed on the mounting portion 431 above the sliding bearing 44 through fasteners to prevent the friction generated when the valve stem moves up and down from bringing the sliding bearing out of the bearing seat.

[0045] In the preferred embodiment described above, a valve stem support structure is provided between the first and second mounting plates, and between the third and fourth mounting plates. This structure supports the valve stem, preventing the defect of increased coaxiality caused by an extended valve stem. Furthermore, the PTFE sliding bearing reduces the valve stem's friction coefficient, lubricates the valve stem, and reduces valve operating torque.

[0046] 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, and the fifth positioning portion 434 cooperates with the first positioning portion 13 and the second positioning portion 14 to realize the installation and positioning of the upper end bearing seat 43; a third positioning portion 46 is respectively provided on the third mounting plate 41 and the fourth mounting plate 42, and the third mounting plate 41 and the fourth mounting plate 42 are installed and positioned by cooperation of the third positioning portion 46, and a fourth positioning portion 47 is provided on the fourth mounting plate 42, and the fifth positioning portion 434 cooperates with the fourth positioning portion 47 to realize the installation and positioning of the lower end bearing seat 43.

[0047] According to the above preferred embodiment, by respectively providing positioning portions on the mounting plate and the bearing seat, the coaxiality of the extended valve stem can be improved, the friction of the valve stem during its up and down movement can be further reduced, and the valve operating torque can be reduced.

[0048] In the present invention, the second coupling assembly adopts one of the following two implementations, wherein:

[0049] Example 1:

[0050] Preferably, the second coupling assembly includes a second coupling sleeve 30 that is sleeved on the outside of the second valve stem 4 and the third valve stem 5, and a plurality of second through holes 31 are provided at the upper and lower ends of the second coupling sleeve 30. The ends of the second valve stem 4 and the third valve stem 5 are also respectively provided with second pin holes 32 corresponding to the second through holes 31. 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, and 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.

[0051] Preferably, two second pin holes 32 arranged in a cross-like manner are respectively opened at the ends of the second valve stem 4 and the third valve stem 5 along the axial direction, and the third pin 33 and the fourth pin 34 are respectively inserted into the corresponding two second pin holes 32.

[0052] Example 2:

[0053] During the use of gate valves, the inventors discovered that improper operator operation (for example, continuing to push the first valve stem 3 to drive the second valve stem 4 and the third valve stem 5 downward after the gate valve is closed) can easily cause bending deformation between the first valve stem 3, the second valve stem 4, and the third valve stem 5. This can cause the connecting parts (such as the pin) between the valve stem and the coupling assembly to loosen and fall off, causing the coupling assembly to fail and even damage the coupling in severe cases. Furthermore, the inventors discovered that the coupling assembly that fails is often the second coupling assembly rather than the first coupling assembly. Therefore, the second coupling assembly in Example 1 has been improved to form the following preferred embodiment.

[0054] The second coupling assembly includes a coupling sleeve which is sleeved on the outside of the second valve stem 4 and the third valve stem 5 and is formed by splicing a first half coupling sleeve 51 and a second half coupling sleeve 52; a first elastic groove 53 is opened in the middle of the first half coupling sleeve 51, and a second elastic groove 54 is opened 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 between the second valve stem 4 and the third valve stem 5, and the distance between the two elastic grooves corresponding to the connection between the second valve stem 4 and the third valve stem 5 is greater than the distance between the two elastic grooves at other positions. A third through hole 55 is respectively provided at the upper and lower ends of the first half coupling sleeve 51 and the second half coupling sleeve 52. A pin hole corresponding to the third through hole 55 is also respectively provided at the end of the second valve stem 4 and the third valve stem 5. A fixing ring 57 is sleeved on the outside of the first half coupling sleeve 51 and the second half coupling sleeve 52. The fifth pin 56 passes through the fixing ring 57, the third through hole 55 and the pin hole in sequence to connect the first half coupling sleeve 51 and the second half coupling sleeve 52 to the valve stem.

[0055] In the preferred embodiment described above, elastic grooves are provided in the middle portions of the first and second coupling sleeve halves, symmetrically about the junction between the second and third valve stems. This allows the second coupling assembly to elastically deform when the valve stems undergo elastic bending deformation, thereby reducing the probability of coupling assembly failure (damage). Furthermore, because the coupling sleeve is formed by splicing the first and second coupling sleeve halves together, in the event of coupling assembly damage, this structure allows for convenient and rapid replacement of the damaged portion. Furthermore, because the second coupling assembly is subject to significant bending moment at the junction between the second and third valve stems, the distance between the elastic grooves corresponding to the junction between the second and third valve stems is greater than the distance between the elastic grooves at other locations. This enhances the structural strength of the corresponding portion of the second coupling assembly without compromising its overall elastic deformation capacity, thereby preventing damage to the second coupling assembly. Furthermore, the inventors have discovered that coupling assembly failure often occurs in the second coupling assembly, rather than the first. Therefore, the first coupling assembly is not equipped with a structure similar to that described in Example 2.

[0056] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although this specification has described the present invention in detail with reference to the above embodiments, the present invention is not limited to the above specific implementation methods. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the invention are included in the scope of the claims of the present invention.

Claims

1. A buried extended flat gate valve, characterized by: The gate valve comprises a valve body, a valve cover is mounted on the upper end of the valve body, and a segmented extended valve stem assembly is mounted on the upper end of the valve cover; The extended valve stem assembly includes a first bracket, a second bracket, and a third bracket mounted on the upper end of the valve cover and connected in sections in sequence. The first valve stem, the second valve stem, and the third valve stem are disposed inside the bracket and connected in sections in sequence. The first valve stem and the second valve stem are connected by a first coupling assembly, and the second valve stem and the third valve stem are connected by a second coupling assembly different from the first coupling assembly. The upper end of the first valve stem is provided with a threaded section, which is transmission-connected to the valve operating end; the lower end of the third valve stem is connected to a valve plate, which has a channel for fluid circulation; The second coupling assembly includes a coupling sleeve that is sleeved on the outside of the second valve stem and the third valve stem and is formed by splicing a first half coupling sleeve and a second half coupling sleeve; a first elastic groove is opened in the middle of the first half coupling sleeve, and a second elastic groove is opened 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 about 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.

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

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

4. The flat gate valve according to claim 3, characterized in that: 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, a fourth mounting plate is provided at the upper end of the third bracket, and 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.

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

6. The flat gate valve according to claim 5, characterized in that: A fifth positioning portion is provided on the bearing seat, and a first positioning portion and a second positioning portion are provided on the first mounting plate and the second mounting plate respectively, and the fifth positioning portion cooperates with the first positioning portion and the second positioning portion respectively to realize the installation and positioning of the upper end bearing seat; a third positioning portion is provided on the third mounting plate and the fourth mounting plate respectively, and the third mounting plate and the fourth mounting plate are installed and positioned by cooperating with the third positioning portion, and a fourth positioning portion is provided on the fourth mounting plate, and the fifth positioning portion cooperates with the fourth positioning portion to realize the installation and positioning of the lower end bearing seat.

7. The flat gate valve according to claim 6, characterized in that: A third through hole is respectively formed at the upper and lower ends of the first half coupling sleeve and the second half coupling sleeve, and a pin hole corresponding to the third through hole is also respectively formed at the end of the second valve stem and the third valve stem. A fixing ring is sleeved on the outside of the first half coupling sleeve and the second half coupling sleeve, and a fifth pin passes through the fixing ring, the third through hole and the pin hole in sequence to connect the first half coupling sleeve and the second half coupling sleeve to the valve stem.

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