A gate valve for preventing thermal expansion and external leakage

Abstract

This invention discloses a gate valve for preventing thermal expansion and external leakage, relating to the field of valve technology. It includes a valve body, a gate, a valve cover, and an upper valve stem. A flow-dividing cylinder is located below the valve body, and the flow-dividing cylinder has a flow-dividing chamber. A piston is located within the flow-dividing chamber, and a lower valve stem is located on the piston. The upper end of the lower valve stem extends through the cylinder body of the flow-dividing cylinder and connects to the gate, and can be linked with the upper valve stem. An arc groove is provided at the upper end of the cylinder body of the flow-dividing cylinder. A switching mechanism is located within the flow-dividing cylinder, and the switching mechanism has a switching hole. The switching mechanism, in conjunction with the lower valve stem, can change the position of the switching hole, thereby controlling the connection or disconnection between the flow-dividing chamber and the valve body cavity. This invention can alleviate medium pressure at high temperatures, effectively reducing the medium compression force on the packing and preventing leakage.

Description

Technical Field

[0001] This invention relates to the field of valve technology, and specifically to a gate valve that prevents external leakage due to thermal expansion. Background Technology

[0002] A gate valve is a valve whose opening and closing element is a gate, and the direction of the gate's movement is perpendicular to the direction of fluid flow. It can only be fully open or fully closed, and cannot be used for regulation or throttling. Gate valves are mainly used in engineering industries such as petroleum, petrochemical, power, and water conservancy. A gate valve mainly consists of a valve body, gate, valve stem, valve cover, support, and drive system. The seal between the valve stem and the valve cover usually adopts a packing seal structure. When traditional gate valves are used in liquid conditions such as oil and water, in the valve open state, the upper sealing block at the lower part of the valve stem and the upper sealing surface at the top of the middle cavity form a seal, and the packing groove is not affected by the impact of high-pressure medium. In the valve closed state, the upper sealing block disengages from the upper sealing surface, and the middle cavity is filled with high-pressure medium.

[0003] When a fire or high temperature occurs in the external environment, the high-pressure medium in the middle cavity of the existing gate valve is easily heated and expanded. The pressure of the high-pressure medium continues to rise, and the packing in the packing groove is squeezed by the high-pressure medium. The medium is prone to leakage from the fit between the packing and the inner wall of the packing groove and the fit between the packing and the valve stem, which affects the use. Summary of the Invention

[0004] To address the problem that existing gate valves are prone to leakage due to medium pressure rising and compressing the packing under high temperatures, this invention provides a gate valve that can alleviate medium pressure under high temperatures and effectively reduce the pressure exerted on the packing by the medium, thus preventing thermal expansion and external leakage.

[0005] The technical solution provided by this invention is as follows:

[0006] A gate valve for preventing thermal expansion and external leakage includes a valve body with a medium flow channel and a valve seat within the medium flow channel. A valve cover is mounted on the valve body, and a gate plate is located within the valve body. The gate plate has a sealing surface that forms a sealing fit with the valve seat. The upper end of the valve body and the outer side of the gate plate form a valve cavity. An upper valve stem is located at the upper end of the gate plate. The upper valve stem extends upward through the valve cover and is connected to a handwheel via a threaded sleeve. The upper valve stem has an anti-rotation mechanism. Packing material is provided between the upper valve stem and the valve cover. Rotation of the handwheel causes the upper valve stem to move up and down, thereby causing the gate plate to move up and down. The device is equipped with a diversion cylinder, which has a diversion chamber. A piston is installed inside the diversion chamber, and a lower valve stem is installed on the piston. The upper end of the lower valve stem extends out of the cylinder body of the diversion cylinder and is connected to a gate plate, and can be linked with the upper valve stem. The upper end of the cylinder body of the diversion cylinder has an arc groove. A switching mechanism is installed inside the diversion cylinder, and the switching mechanism has a switching hole. The switching mechanism can change the position of the switching hole by working in conjunction with the lower valve stem. The switching hole has a first position that communicates with the arc groove so that the medium can flow between the middle cavity and the diversion chamber, and a second position that is misaligned with the arc groove so that the medium cannot flow from the middle cavity into the diversion chamber.

[0007] The upper valve stem is provided with an upper sealing block at its lower part, the valve cover is provided with an upper sealing surface that cooperates with the upper sealing block, the gate is provided with a movable groove, a pull head is movably disposed in the movable groove, and both ends of the movable groove are provided with limiting protrusions to prevent the pull head from disengaging from the movable groove. The upper valve stem and the lower valve stem are respectively fixed to both ends of the pull head.

[0008] An elastic element is provided between the pull head and the lower end face of the movable groove.

[0009] The valve cover is provided with a bracket at the upper end. The anti-rotation mechanism includes an anti-rotation rod and an anti-rotation groove. The anti-rotation rod is located between the valve cover and the handwheel. The anti-rotation groove is located on the bracket. One end of the anti-rotation rod is inserted into the upper valve stem, and the other end is inserted into the anti-rotation groove.

[0010] The switching mechanism includes a switching head and a switching rod. The switching head is located above the flow divider cylinder. The switching rod extends downward from the lower end of the switching head into the flow divider cylinder body and is sleeved on the outside of the lower valve stem. The switching hole is located in the switching head. The lower valve stem is provided with a drive key. The switching rod is provided with a rotating structure that cooperates with the drive key. The drive key moves up and down with the lower valve stem, which drives the switching rod to rotate, thereby driving the switching head to rotate and change the position of the switching hole.

[0011] A planar bearing is provided between the switching head and the valve body.

[0012] The rotating structure includes an upper sliding groove, a spiral groove, and a lower sliding groove. The upper sliding groove and the lower sliding groove are centrally symmetrical about the center of the switching rod. The spiral groove is inclined and connects the upper sliding groove and the lower sliding groove.

[0013] The switching rod is fitted with a tail sleeve on its outer side. The tail sleeve is integrally formed with the piston, and a first sealing ring is provided between the tail sleeve and the lower valve rod.

[0014] A check valve is provided at the second position corresponding to the switching hole of the flow divider cylinder body.

[0015] The distance between the check valve and the end of the arc groove is less than the diameter of the switching hole.

[0016] The beneficial effects of this invention are as follows: By setting a diversion chamber below the gate valve body and controlling the connection or disconnection between the diversion chamber and the valve body cavity through a switching mechanism, when the valve is closed, the cavity is connected to the diversion chamber, and part of the high-pressure liquid medium in the cavity is diverted to the diversion chamber, leaving the upper part of the cavity empty. When a fire or high temperature occurs externally, the liquid medium in the cavity expands due to heat and must first refill the empty cavity in the upper part of the cavity before the medium can compress the packing. At the same time, since the weight of the liquid medium remains constant, the increased storage space greatly reduces the pressure of the liquid medium, effectively reducing the medium compression force on the packing, and further preventing leakage at the fit between the packing and the inner wall of the packing groove and at the fit between the packing and the valve stem, thus extending the service life of the gate valve. Attached Figure Description

[0017] Figure 1 This is a cross-sectional structural diagram of an embodiment of the present invention;

[0018] Figure 2 This is a cross-sectional structural diagram of the closed state according to an embodiment of the present invention;

[0019] Figure 3 This is a cross-sectional structural diagram of the open state according to an embodiment of the present invention;

[0020] Figure 4 for Figure 3 A magnified view of a portion of the image;

[0021] Figure 5 for Figure 2 A schematic diagram of the A-direction switching head and the top of the diversion cylinder;

[0022] Figure 6 for Figure 3 A schematic diagram of the B-direction switching head and the top of the diversion cylinder;

[0023] Figure 7 This is a schematic diagram of the internal structure of the switching lever in an embodiment of the present invention.

[0024] Among them, 1-valve body, 2-gate, 3-lower valve stem, 4-spring, 5-medium flow channel, 6-left valve seat, 7-limiting protrusion, 8-upper sealing block, 9-middle cavity, 10-upper valve stem, 11-valve cover, 12-upper sealing surface, 13-gap, 14-packing, 15-gland, 16-bracket, 17-sleeve, 18-handwheel, 19-anti-rotation groove, 20-anti-rotation rod, 21-partition one, 22-partition two, 23- -Right valve seat, 24-Moving groove, 25-Pull head, -26-Side bearing, 27-Switching head, 28-Check valve, 29-Flow divider cylinder, 30-Upper sliding groove, 31-Switching rod, 32-Cap, 33-Tail sleeve, 34-Breath hole, 35-Piston, 36-Drive key, 37-Lower sliding groove, 38-Circular arc groove, 39-Switching hole, 40-Helical groove, 41-Flow divider chamber, 42-Breath chamber, 43-Sealing gasket. Implementation

[0025] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, a gate valve for preventing thermal expansion and external leakage includes a valve body 1, a medium flow channel 5 on the lower side of the valve body 1, a left valve seat 6 and a right valve seat 23 inside the medium flow channel 5, a valve cover 11 on the valve body 1, and a gate plate 2 inside the valve body 1. The gate plate 2 has sealing surfaces corresponding to the left valve seat 6 and the right valve seat 23 to form a sealing fit. The part of the valve body 1 located at the upper end of the medium flow channel 5 and the outer side of the gate plate 2 form a valve cavity 9. The part of the valve body 1 located at the upper end of the medium flow channel 5 is flask-shaped with a larger upper part and a smaller lower part, which increases the medium storage space. The upper end of the gate plate 2 is provided with an upper valve stem 10, which extends upward through the valve cover 11 and is connected to a handwheel 18 through a threaded sleeve 17. The lower end of the upper valve stem 10 is provided with an upper sealing block 8, and the valve cover 11 is provided with an upper sealing surface 12 that cooperates with the upper sealing block 8. A bracket 16 is provided at the upper end of the valve cover 11. An anti-rotation rod 20 is provided between the valve cover 11 and the handwheel 18. An anti-rotation groove 19 is provided on the bracket 16. One end of the anti-rotation rod 20 is inserted into the upper valve stem 10, and the other end is inserted into the anti-rotation groove 19, ensuring that there is a packing 14 between the upper valve stem 10 and the valve cover 11. The packing 14 is used to prevent the fluid medium in the valve body 1 from leaking out and to improve the sealing performance of the valve.

[0027] In this embodiment, a flow divider cylinder 29 is provided below the valve body 1. A flow divider chamber 41 is provided inside the flow divider cylinder 29, and a piston 35 is provided inside the flow divider chamber 41. A lower valve rod 3 is provided on the piston 35. The gate plate 2 is provided with a movable groove 24, and a pull head 25 is movably disposed within the movable groove 24. Limiting protrusions 7 are provided at both ends of the movable groove 14 to prevent the pull head 25 from disengaging from the movable groove. The upper valve rod 10 and the lower valve rod 3 are respectively fixed to the two ends of the pull head 25. Rotating the handwheel 18 will drive the screw sleeve 17 to move the upper valve rod 10 up and down, thereby moving the pull head 25 and the lower valve rod 3 up and down. When the pull head 25 moves to the top of the movable groove 24, the gate plate 2 will be pulled upward by the pull head to open the valve due to the limiting protrusion 7. Conversely, when the pull head 25 moves to the bottom of the movable groove 24, the gate plate 2 will be pressed downward by the pull head to close the valve due to the limiting protrusion 7. Furthermore, a spring 4 can be installed between the pull head 25 and the lower end face of the movable groove 14. When the pull head 25 moves downward in the movable groove 24, the spring 4 is gradually compressed, and the gate plate 2 moves downward under the pressure of the spring to close the valve.

[0028] like Figure 4-7 As shown, the upper end of the cylinder body of the flow divider 29 is provided with an arc groove 38. The flow divider 29 is provided with a switching head 27 and a switching rod 31. The switching head 27 is located above the flow divider 29. The switching rod 31 extends downward from the lower end of the switching head 27 into the cylinder body of the flow divider 29 and is sleeved on the outside of the lower valve rod 3. The switching head 27 is provided with a switching hole 39. The lower valve rod 3 is provided with a drive key 36. The switching rod 31 is provided with a rotating structure that cooperates with the drive key 36.

[0029] like Figure 7 As shown, the rotating structure in this embodiment includes an upper sliding groove 30, a spiral groove 40, and a lower sliding groove 37. The upper sliding groove 30 and the lower sliding groove 37 are centrally symmetrically arranged with the center of the switching rod 31 as the reference. The lengths of the upper sliding groove 30 and the lower sliding groove 37 correspond to the movement path of the pull head 25 in the movable groove 14. The spiral groove 40 is inclined and connects the upper sliding groove 30 and the lower sliding groove 37. Since the upper valve rod 10 is equipped with an anti-rotation mechanism, the upper and lower valve rods can only move up and down. Therefore, while the driving key 36 moves upward in the spiral groove 40, it will drive the switching rod 31 and the switching head 27 to rotate, thereby causing the switching hole 39 to move along the direction of the arc groove 38. Furthermore, a plane bearing 26 is provided between the switching head 27 and the valve body 1 to make the switching head 27 rotate smoothly and switch smoothly. A tail sleeve 33 is sleeved on the outside of the switching rod 31. The tail sleeve 33 is integrally formed with the piston 35. A first sealing ring is provided between the tail sleeve 33 and the lower valve rod 3 to ensure sealing.

[0030] like Figure 5-6As shown, the switching hole 39 has a first position that communicates with the arc groove 38 to allow the medium to flow between the middle cavity and the diversion cavity, and a second position that is misaligned with the arc groove 38 to prevent the medium from flowing from the middle cavity into the diversion cavity. The cylinder body of the diversion cylinder 29 is provided with a check valve 28 corresponding to the second position of the switching hole 39. The check valve 28 can prevent the medium from flowing from the middle cavity into the diversion cavity. Furthermore, the distance L2 between the check valve 28 and the end of the arc groove 38 is smaller than the orifice L1 of the switching hole 39. When the switching hole 39 moves to the gap between the arc groove 38 and the check valve 28, the medium can still flow from the diversion cavity to the switching hole 39 through the check valve, thereby flowing into the middle cavity. This reduces the medium pressure in the diversion cavity, allowing the piston 35 to continue to rise without causing the piston 35 to jam.

[0031] like Figure 1-3 As shown, the operation of this valve is as follows:

[0032] Opening process: Rotating the handwheel 28 clockwise rotates the screw sleeve 17, thereby moving the upper valve stem 10 upward. Under the action of the spring 4, the gate plate 2 remains in the same position. The upper valve stem 10 moves the lower valve stem 3 upward, which in turn moves the piston 35 and the tail sleeve 33 upward. The medium in the diversion chamber 41 is discharged into the middle chamber 9 through the arc groove 38 and the switching hole 39 in sequence. When the pull head 25 moves to the top of the movable groove 24, the pull head 25 continues to move upward, moving the gate plate 2 upward, opening the valve. The driving key 36 moves from the sliding groove 37 to the spiral groove 40. Due to the setting of the anti-rotation rod 20 and the anti-rotation groove 19, the upper and lower valve stems can only... The drive key 36 moves upward within the spiral groove 40, simultaneously rotating the switching rod 31 and the switching head 27. The switching hole 39 moves along the arc groove 38. When the switching hole 39 moves above the arc groove 38 and the check valve 28, the medium in the diversion chamber 41 enters the switching hole 39 through the arc groove 38 and the check valve 28, and then flows to the middle chamber 9. When the drive key 36 moves from the spiral groove 40 into the upper sliding groove 30, the switching hole 39 moves directly above the check valve 28. At this time, the liquid medium in the diversion chamber 41 enters the middle chamber 9 sequentially through the check valve 28 and the switching hole 39. Continuing to rotate the handwheel 28 moves the upper valve stem 10 and the gate 2 upward until fully open. At this time, the upper sealing block 8 presses against the upper sealing surface 12 to form a seal, isolating the packing 14 from the middle chamber 9.

[0033] Closing process: Rotating the handwheel 28 counterclockwise rotates the screw sleeve 17, thereby causing the upper valve stem 10 and the lower valve stem 3 to move downwards. This, in turn, causes the piston 35 and the tail sleeve 33 to move downwards, driving the flat key 36 to move downwards along the upper slide groove 30. The volume of the diversion chamber 41 increases. Under the action of the spring 4, the gate 2 also moves downwards. When the gate 2 forms a seal with the left and right valve seats, the gate 2 can no longer move downwards. However, the upper and lower valve stems continue to move downwards under the action of the handwheel 28. The spring 4 is compressed, driving the flat key 36 from the upper slide groove 30 into the spiral groove 40. Due to the setting of the anti-rotation rod 20 and the anti-rotation groove 19, the upper and lower valve stems... Since the valve stem can only move up and down, when the drive key 36 moves downward in the spiral groove 40, it drives the switching rod 31 and the switching head 27 to rotate in opposite directions. The switching hole 39 moves above the arc groove 38, and the liquid medium in the middle cavity 9 enters the diversion cavity 41 through the switching hole 39 and the arc groove 38 in sequence. At this time, the upper part of the middle cavity 9 becomes an empty cavity, and the medium will not squeeze the packing. Continue to rotate the handwheel 28 to drive the upper and lower valve stems to move down, and the piston 35 and the tail sleeve 33 continue to move down. Drive the key 36 from the spiral groove 40 into the sliding groove 37 and continue to move down. The space of the diversion cavity 41 continues to increase until the spring 4 is compressed.

[0034] When this valve is closed, the central cavity 9 connects to the diversion cavity 41. Some of the high-pressure liquid medium in the central cavity 9 will be diverted to the diversion cavity 41, and the upper part of the central cavity 9 becomes an empty cavity. When a fire or high temperature occurs outside, the liquid medium in the central cavity 9 will expand due to heat and must first refill the empty cavity in the upper part of the central cavity before the medium can squeeze the packing. At the same time, since the weight of the liquid medium remains constant, the increased storage space greatly reduces the pressure of the liquid medium, effectively reducing the pressure of the medium on the packing. This further prevents leakage at the fit between the packing and the inner wall of the packing groove 21 and the fit between the packing and the valve stem 22, thus extending the service life of the gate valve.

[0035] The embodiments should not be construed as limiting the present invention, and any non-creative improvements made based on the spirit of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A gate valve for preventing thermal expansion and external leakage, comprising a valve body, a medium flow channel in the valve body, a valve seat within the medium flow channel, a valve cover on the valve body, a gate plate within the valve body, a sealing surface forming a sealing fit with the valve seat, the upper end of the valve body and the outer side of the gate plate forming a valve cavity, an upper valve stem at the upper end of the gate plate, the upper valve stem extending upward through the valve cover and connected to a handwheel via a threaded sleeve, the upper valve stem having an anti-rotation mechanism, packing material between the upper valve stem and the valve cover, and rotation of the handwheel causing the upper valve stem to move up and down, thereby causing the gate plate to move up and down, characterized in that: A flow divider cylinder is provided below the valve body. The flow divider cylinder has a flow divider chamber. A piston is provided in the flow divider chamber. A lower valve rod is provided on the piston. The upper end of the lower valve rod passes through the cylinder body of the flow divider cylinder and is connected to the gate plate and can be linked with the upper valve rod. The upper end of the cylinder body of the flow divider cylinder has an arc groove. A switching mechanism is provided inside the flow divider cylinder. The switching mechanism has a switching hole. The switching mechanism can change the position of the switching hole by linkage with the lower valve rod. The switching hole has a first position that communicates with the arc groove so that the medium can flow between the middle cavity and the flow divider chamber, and a second position that is misaligned with the arc groove so that the medium cannot flow from the middle cavity into the flow divider chamber. The switching mechanism includes a switching head and a switching rod. The switching head is located above the flow divider cylinder. The switching rod extends downward from the lower end of the switching head into the cylinder body of the flow divider cylinder and is sleeved on the outside of the lower valve rod. The switching hole is located in the switching head. The lower valve rod is provided with a drive key. The switching rod is provided with a rotating structure that cooperates with the drive key. The drive key moves up and down with the lower valve rod, which drives the switching rod to rotate, thereby driving the switching head to rotate and change the position of the switching hole. The rotating structure includes an upper sliding groove, a spiral groove, and a lower sliding groove. The upper sliding groove and the lower sliding groove are centrally symmetrical about the center of the switching rod. The spiral groove is inclined and connects the upper sliding groove and the lower sliding groove.

2. The gate valve for preventing thermal expansion and external leakage according to claim 1, characterized in that: The upper valve stem is provided with an upper sealing block at its lower part, the valve cover is provided with an upper sealing surface that cooperates with the upper sealing block, the gate is provided with a movable groove, a pull head is movably disposed in the movable groove, and both ends of the movable groove are provided with limiting protrusions to prevent the pull head from disengaging from the movable groove. The upper valve stem and the lower valve stem are respectively fixed to both ends of the pull head.

3. The gate valve for preventing thermal expansion and external leakage according to claim 2, characterized in that: An elastic element is provided between the pull head and the lower end face of the movable groove.

4. The gate valve for preventing thermal expansion and external leakage according to claim 1, characterized in that: The valve cover is provided with a bracket at the upper end. The anti-rotation mechanism includes an anti-rotation rod and an anti-rotation groove. The anti-rotation rod is located between the valve cover and the handwheel. The anti-rotation groove is located on the bracket. One end of the anti-rotation rod is inserted into the upper valve stem, and the other end is inserted into the anti-rotation groove.

5. A gate valve for preventing thermal expansion and external leakage according to claim 1, characterized in that: A planar bearing is provided between the switching head and the valve body.

6. The gate valve for preventing thermal expansion and external leakage according to claim 1, characterized in that: The switching rod is fitted with a tail sleeve on its outer side. The tail sleeve is integrally formed with the piston, and a first sealing ring is provided between the tail sleeve and the lower valve rod.

7. The gate valve for preventing thermal expansion and external leakage according to claim 1, characterized in that: A check valve is provided at the second position corresponding to the switching hole of the flow divider cylinder body.

8. A gate valve for preventing thermal expansion and external leakage according to claim 7, characterized in that: The distance between the check valve and the end of the arc groove is less than the diameter of the switching hole.

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