Gate valve

Abstract

[Problem] To provide a gate valve capable of applying a variation in the strength of the pressing force of a valve plate during sealing operation. [Solution] A gate valve 1 (1A) according to the present invention opens and closes openings 7, 8, which are provided on both side surfaces of a valve box 2, using a valve plate 3 (10, 11) disposed inside the valve box 2. The gate valve 1 is provided with: a valve rod 4 that is coupled to the valve plate 3, and is supported so as to be movable up / down and tiltable inside the valve box 2; a drive mechanism 5 that is provided outside the valve box 2, and moves up / down and tilts the valve rod 4 by a predetermined stroke; and a stopper mechanism 6 that is provided in the middle of the stroke of the drive mechanism 5, and regulates or releases the rise of the valve rod 4 by supplying or stopping compressed air. The stopper mechanism 6 changes the inclination angle of the valve rod 4 by varying the height position of the drive mechanism 5 that tilts the valve rod 4, thereby applying a variation in the strength of the pressing force of the valve plate 3.

Description

Gate valve

[0001] The present invention relates to a double-sided seal gate valve that is used, for example, in a semiconductor manufacturing device and is installed between two chambers.

[0002] A known example of this type of valve is the bidirectional gate valve described in Patent Document 1 below. This gate valve has first and second blades that operate independently on the top and bottom. If the first blade fails, the second blade is activated, allowing the first blade to be repaired while continuing to open and close the travel path. The L-motion block and moving unit, which move the first blade vertically and horizontally, each have first through third rollers. The inner sides of both sides of the lower housing are provided with rotation guide grooves, L-motion block movement grooves, and moving unit guide grooves into which the first through third rollers are inserted, enabling accurate movement of the first blade. The second rollers are guided by guide links formed on both sides of the L-motion block, enabling accurate operation of the first blade when the L-motion block moves up, down, left, and right.

[0003] Japanese Patent Application Laid-Open No. 2017-062031

[0004] The conventional gate valve has two blades, one above the other, that operate independently. Even if the first blade fails due to a mechanical defect, the second blade can still operate, smoothly opening and closing the first and second passages, allowing for repairs and maintenance of the first blade. However, this gate valve does not allow for adjustment of the pressure applied by the blades during sealing operation, and must always apply a strong pressure to withstand back pressure. This creates the problem of frequent wear and deformation of the packing during sealing, necessitating frequent repairs and replacement.

[0005] The present invention has been made to solve these problems, and its object is to provide a gate valve that can adjust the strength of the pressing force of the valve plate during sealing operation.

[0006] In order to achieve the above-mentioned object, the gate valve of the present invention is a gate valve in which openings provided on both sides of a valve box are opened and closed by a valve plate located inside the valve box, and comprises: a valve rod connected to the valve plate and supported so as to be able to rise and fall and tilt within the valve box; a drive mechanism provided outside the valve box for raising and lowering and tilting the valve rod a predetermined stroke; and a stopper mechanism provided midway through the stroke of the drive mechanism for restricting or releasing the rise of the valve rod by supplying or stopping compressed air, wherein the stopper mechanism changes the height position of the drive mechanism which tilts the valve rod, thereby changing the inclination angle of the valve rod and varying the strength of the pressing force of the valve plate.

[0007] Furthermore, in the gate valve having the above-described configuration, the stopper mechanism can employ a structure in which a stopper pin advances or retreats in a horizontal direction perpendicular to the stroke direction of the valve rod to restrict or release the lift of the valve rod.

[0008] Furthermore, in the gate valve having the above-described configuration, the stopper mechanism can employ a structure in which the opening and closing angle of the arm is adjusted by controlling an air piston, thereby varying the height position of the stopper pin at the tip of the arm.

[0009] In addition, in the gate valve having the above-described configuration, the stopper mechanism may adopt a structure in which the rotation angle of the piston rod is adjusted by controlling a rotary actuator, thereby varying the height position of the stopper pin at the tip of the piston rod.

[0010] According to the gate valve of the present invention, the height position of the drive mechanism that tilts the valve rod is variable, thereby changing the inclination angle of the valve rod and varying the strength of the pressing force of the valve plate, so that in the double-sided seal structure, sealing can be performed with an appropriate pressing force depending on whether the seal is a constant pressure seal, a counter pressure seal, or a positive pressure seal. This has the effect of extending the maintenance cycle for repairs and replacements due to wear and deformation of the packing caused by the sealing operation, and thereby extending the service life of the gate valve.

[0011] 1 is an external perspective view showing a first embodiment of a gate valve according to the present invention. FIG. 1 is a cross-sectional view and an enlarged view of a main part showing the gate valve in a fully open state. FIG. 2 is a longitudinal cross-sectional view of the gate valve of FIG. 2. FIG. 1 is a cross-sectional view and an enlarged view of a main part showing the gate valve in a state where the gate valve is sealing under uniform pressure. FIG. 4 is a longitudinal cross-sectional view of the gate valve of FIG. 4. FIG. 1 is a cross-sectional view and an enlarged view of a main part showing the gate valve in a state where the gate valve is sealing under counter pressure. FIG. 6 is a longitudinal cross-sectional view of the gate valve of FIG. 6. FIG. 1 is a cross-sectional view and an enlarged view of a main part showing the gate valve in a state where the gate valve is sealing under positive pressure. FIG. 8 is a longitudinal cross-sectional view of the gate valve of FIG. 8. FIG. 11 is a cross-sectional view and an enlarged view of a main part showing the gate valve in a state where the gate valve is sealing under uniform pressure. FIG. 13 is a cross-sectional view and an enlarged view of a main part showing the gate valve in a state where the gate valve is sealing under counter pressure. FIG. 15 is a longitudinal cross-sectional view of the gate valve of FIG. 15. FIG. 15 is a cross-sectional view and an enlarged view of a main part showing the gate valve in a state where the gate valve is sealing under positive pressure. 18 is a longitudinal cross-sectional view of the gate valve of FIG. 17. FIG. 19 is a cross-sectional view and a perspective view showing a rotary actuator of the gate valve. FIG. 19 is a cross-sectional view and a perspective view showing a rotary actuator (another example) of the gate valve.

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0013] 1 and 2, the gate valve 1 (1A) of this embodiment is a machine for isolating vacuum from vacuum or vacuum from atmosphere in an apparatus for manufacturing flat panel displays or semiconductor substrates, and is used to isolate various processes when manufacturing displays or substrates. This gate valve 1 (1A) is a so-called valve box-type double-sided seal gate valve, and is configured with a flat rectangular valve box 2, a valve plate 3 housed inside the valve box 2, a valve rod 4 connected to the valve plate 3, a drive mechanism 5 for raising and lowering the valve rod 4 by a predetermined stroke and tilting it, and a stopper mechanism 6 for restricting or releasing the lift of the valve rod 4.

[0014] 3, narrow openings (first opening 7 and second opening 8) are provided facing each other on both the left and right wall surfaces of the valve box 2 to allow substrates to pass through. A process chamber PC is connected to the outer wall surface of the first opening 7, and a transfer chamber TC is connected to the outer wall surface of the second opening 8. The substrate transferred from the transfer chamber TC to the process chamber PC through the valve box 2 is kept in a sealed environment by closing the gate valve 1 (1A), and heat, gas, plasma, and other treatments for various film formations are performed inside the process chamber PC.

[0015] A pair of valve plates 3 (a first valve plate 10 and a second valve plate 11) are arranged in the interior space 9 of the valve box 2 to selectively open and close the openings 7 and 8. O-rings 12 and 13 are fitted and fixed to the outer surfaces of the first valve plate 10 and the second valve plate 11 as elastic sealing materials that are slightly larger than the first opening 7 and the second opening 8, respectively.

[0016] The first valve plate 10 and the second valve plate 11 are separably joined by fastening them with bolts 14. The valve plate 3 is formed into a tapered shape that gradually tapers from the lower part to the upper part of the valve plate surface. This inclination of the valve plate surface of the valve plate 3 allows the O-rings 12 and 13 to be pressed parallel to the valve seat (with uniform force) during sealing. The valve rod 4 is detachably attached to the center of the second valve plate 11 with bolts 14. This allows the entire valve plate 3 to be removed from the valve rod 4, or just one of the valve plates 3 (e.g., the first valve plate 10) to be removed. The removed valve plates 3 (10 and 11) can be removed to the outside by removing the maintenance flange 15 covering the top surface of the valve box 2 and opening the lid, allowing maintenance work such as surface cleaning and replacement of the O-rings 12 and 13 to be performed.

[0017] The valve rod 4 passes through the center of a bonnet flange 16 that closes the bottom surface of the valve body 2, and extends to the outside of the valve body 2. A rod guide 17 that supports the valve rod 4 and guides its movement is provided at the middle position of the valve rod 4. In addition, an expandable metal bellows 18, such as a welded bellows or a formed bellows, is attached between the rod guide 17 and the bonnet flange 16 so as to cover the periphery of the valve rod 4, completely isolating the valve rod 4 from the outside.

[0018] A fulcrum roller 19 is provided above the rod guide 17 and is rotatably supported by a roller guide 20 that supports the valve box 2. A direction switching roller 21 is provided at the lower end of the valve rod 4. The direction switching roller 21 is engaged with a cam groove 23, which is curved with a V-shaped cross section and provided in a cam 22, and is slidably supported. A cam plate 24 that supports the cam 22 is integrally connected to the lower end of the cam 22. A coil spring 25 is attached between the cam plate 24 and the rod guide 17, and a rod 27 of an air cylinder 26 for lifting and lowering, which serves as the drive mechanism 5, is connected to the center of the lower end of the cam plate 24. Load-receiving rollers 28, which serve as force points, are attached to both left and right ends of the cam plate 24 and are supported so that they can be raised and lowered along the roller guide 20.

[0019] When the air cylinder 26 is driven by the drive mechanism 5, the valve rod 4 moves up and down a predetermined stroke via the cam 22 connected to the cam plate 24, and the valve plate 3 attached to the valve rod 4 moves to a predetermined height within the valve box 2 and stops there. When the direction switching roller 21 is at the upper end position (center) of the cam groove 23, the valve rod 4 stands up in the center of the valve box 2, when it is at the intermediate position (left side) of the cam groove 23, the valve rod 4 rotates around the fulcrum roller 19 as an axis and tilts to the right, and when it is at the lower end position (right side) of the cam groove 23, the valve rod 4 rotates around the fulcrum roller 19 as an axis and tilts to the left. As a result, when the cam groove 23 is at its upper end position, the valve plate 3 (10, 11) attached to the valve rod 4 opens both openings 7 and 8 as shown in Figure 3, when the cam groove 23 is at its intermediate position, the first valve plate 10 closes the first opening 7 as shown in Figures 5 and 7, and when the cam groove 23 is at its lower end position, the second valve plate 11 closes the second opening 8 as shown in Figure 9.

[0020] The stopper mechanism 6 is provided midway through the stroke of the air cylinder 26, and has the function of moving a stopper pin 30 forward or backward horizontally by supplying or stopping compressed air, thereby restricting or releasing the upward movement of the valve rod 4. In this embodiment, the stopper mechanism 6 is provided with open / close arm type stopper pins 30 using air pistons 29 on both the left and right sides of the drive mechanism 5.

[0021] The air piston 29 has a multiple structure in which piston rods 31, 31, ... are lined up horizontally on the left, center, and right, and each has a piston 35 sealed with a packing 34 in an enclosed space formed by a rod cover 33 attached to a cylinder 32. In addition, each of the air pistons 29 on the left and right sides has a piston rod 31 biased by a spring 36 housed in the enclosed space, with the tip of the piston rod 31 penetrating the center of the rod cover 33 and protruding to the outside. The enclosed space is divided into a head-side space 37 and a rod-side space 38 by the piston 35 provided on the piston rod 31, and a compressed air supply port 40 connected to air piping 39 (A, B, C) is attached to the head-side space 37.

[0022] The stopper pin 30 has a stepped tip with contact surfaces at different heights (a first contact surface 41 at a lower position and a second contact surface 42 at a higher position), and is attached to the upper end of a linear arm 44 via a joint 43. The lower end of the arm 44 is connected to the tip of the piston rod 31 via a joint 45, and the piston rod 31, arm 44, and stopper pin 30 form an integrated link mechanism. A load-bearing roller 28 is installed above the cam plate 24 opposite the stopper pin 30, corresponding to the position of the pin tip. Although not shown, the tip of the stopper pin 30 may be provided with a slit or a counterbore as a vibration-reducing means to mitigate impact upon collision with the load-bearing roller 28.

[0023] The above is the structure of the gate valve 1 (1A) of this embodiment, and its operation will now be described. Figures 2 and 3 show the gate valve 1 (1A) in its fully open state, Figures 4 and 5 show its state when sealing under equal pressure, Figures 6 and 7 show its state when sealing under counter pressure, and Figures 8 and 9 show its state when sealing under positive pressure.

[0024] As shown in Figures 2 and 3, when the gate valve 1 (1A) is not operating, the transfer chamber TC and the process chamber PC are open to the atmosphere, and both chambers are at the same pressure. At this time, the drive mechanism 5 is stopped, the valve rod 4 is lowered, and the direction switching roller 21 is at the upper end (center) of the cam groove 23. As a result, the valve rod 4 stands upright at the center of the valve box 2, and the first valve plate 10 and the second valve plate 11 are lowered below the first opening 7 and the second opening 8, respectively, in an open (OPEN) state. In this "OPEN" state, substrates can pass from the transfer chamber TC to the process chamber PC via the second opening 8 and the first opening 7.

[0025] Furthermore, the supply of compressed air from the air pipes 39 (A, B, C) to the air piston 29 of the stopper mechanism 6 is stopped, and the piston rods 31 on both the left and right sides are pressed toward the center by the spring force of the spring 36. As a result, the arm 44 connected to the piston rod 31 is in a vertically standing state, and the tip of the stopper pin 30 attached to the upper end of the arm 44 is retracted to the end face of the roller guide 20. Therefore, the load-receiving roller 28 of the cam plate 24 does not collide with the tip of the stopper pin 30, the stopper function is released, and the valve rod 4 can rise to the stroke end of the air cylinder 27.

[0026] 4 and 5, during normal operation of the gate valve 1 (1A), the transfer chamber TC and the process chamber PC are at the same pressure (atmosphere to atmosphere, or vacuum to vacuum), and only the process chamber PC side is sealed. To achieve this, compressed air is supplied to the air piston 29 of the stopper mechanism 6 from air pipes 39 (A and C) on both the left and right sides, as shown in FIG.

[0027] As a result, compressed air is supplied from the compressed air supply ports 40 into the head-side spaces 37 of the air pistons 29 on both the left and right sides, and the piston rods 31 are pushed outward against the spring force of the springs 36. The pistons 35 then strike the inner wall surface of the rod cover 33, and the tip of the piston rod 31 protrudes a maximum amount from the outer wall surface of the rod cover 33. As a result, the arm 44 connected to the piston rod 31 tilts at the maximum angle (opening / closing angle of 6 degrees) with the joint 45 as its starting point. As a result, the tip of the stopper pin 30 attached to the upper end of the arm 44 advances horizontally in a direction perpendicular to the stroke direction of the valve rod 4, and protrudes from the end face of the roller guide 20 to the first abutment surface 41.

[0028] Here, by driving the air cylinder 26 of the drive mechanism 5, the entire cam plate 24 is pushed up from below by the force of compressed air, compressing the coil spring 25 and causing the valve rod 4 to rise a predetermined stroke via the cam 22 connected to the cam plate 24. Furthermore, when the fulcrum roller 19 of the rod guide 17 hits the upper end of the groove in the roller guide 20, the valve plate 3 (10, 11) moves to a height position corresponding to the openings 7, 8. At this time, the air cylinder 27 still has some stroke remaining.

[0029] Then, the direction switching roller 21 starts to move along the cam groove 23 and starts the sealing operation. At this time, the load receiving roller 28 collides with and catches the first abutment surface 41 of the stopper pin 30, causing the direction switching roller 21 to move to the middle position (left side) of the cam groove 23 and tilt the valve rod 4 to the right. As a result, the first valve plate 10 comes into contact with the first opening 7, sealing the first opening 7 and completing the sealing operation. This is the "same pressure seal" operation.

[0030] 6 and 7, during maintenance of the process chamber PC, the transfer chamber TC is at vacuum and the process chamber PC is at atmospheric pressure, and only the process chamber PC side is sealed in a counter-pressure state. To achieve this, the supply of compressed air from the air pipes 39 (A and C) on both the left and right sides of the air piston 29 of the stopper mechanism 6 is stopped, and compressed air is supplied only from the central air pipe 39 (B), as shown in FIG.

[0031] As a result, the piston rods 31 of the air pistons 29 on both sides are pressed toward the center by the spring force of the springs 36. However, for the central air piston 29, compressed air is supplied from the compressed air supply port 40 into the head-side space 37, so the piston rod 31 is pushed outward against the spring force of the springs 36 by the stroke of the central air piston 29. The piston 35 then stops at an intermediate position within the sealed space, and the tip of the piston rod 31 protrudes slightly from the outer wall surface of the rod cover 33. As a result, the arm 44 connected to the piston rod 31 tilts at a smaller angle (opening / closing angle of 3 degrees) with the joint 45 as its starting point. As a result, the tip of the stopper pin 30 attached to the upper end of the arm 44 advances horizontally in a direction perpendicular to the stroke direction of the valve rod 4, and only the second abutment surface 42 protrudes from the end surface of the roller guide 20.

[0032] At this point, the direction switching roller 21 moves along the cam groove 23 and begins the sealing operation. At this time, the load-receiving roller 28 collides with the second abutment surface 42 of the stopper pin 30, and the direction switching roller 21 moves from the intermediate position (left side) of the cam groove 23 to a position slightly lower, tilting the valve rod 4 further to the right. As a result, the first valve plate 10 is brought into contact with the first opening 7 with a stronger force than before, sealing the first opening 7 and completing the sealing operation. This is the "counter pressure sealing" operation. In this way, by varying the height position of the stopper pin 30, the strength of the pressing force of the first valve plate 10 during equal pressure sealing and counter pressure sealing can be varied depending on the height position of the direction switching roller 21.

[0033] Finally, as shown in Figures 8 and 9, during maintenance of the gate valve 1 (1A), the transfer chamber TC is vacuum, the process chamber PC is atmospheric, and only the transfer chamber TC side is sealed in a positive pressure state. To achieve this, the supply of compressed air from all air pipes 39 (A, B, C) to the air piston 29 of the stopper mechanism 6 is stopped, as shown in Figure 8. This causes the piston rods 31 on both sides to elastically return to their pressed-together positions due to the spring force of the springs 36. This causes the arm 44 connected to the piston rod 31 to stand vertically, and the tip of the stopper pin 30 attached to the upper end of the arm 44 moves horizontally, returning to its retracted position at the end face of the roller guide 20.

[0034] When the air cylinder 26 is driven, the entire cam plate 24 is pushed up from below by the force of compressed air, compressing the coil spring 25 and causing the valve rod 4 to rise a predetermined stroke via the cam 22 connected to the cam plate 24. At this time, the load-receiving roller 28 of the cam plate 24 does not collide with the tip of the stopper pin 30, and the restriction on the valve rod 4 is released, so the valve rod 4 rises to the stroke end of the air cylinder 26. At this time, the direction switching roller 21 begins to move along the cam groove 23 and initiates a sealing operation. At this time, the direction switching roller 21 moves to the lower end position (right side) of the cam groove 23, tilting the valve rod 4 to the left. This causes the second valve plate 11 to come into contact with the second opening 8, sealing the second opening 8 and completing the sealing operation. This is the "positive pressure sealing" operation.

[0035] In this "positive pressure seal" state, the first valve plate 10 can be removed to the outside of the valve box 2 by removing the maintenance flange 15 of the valve box 2 to open the lid, and loosening the bolts 14 to remove the first valve plate 10 from the valve rod 4. Therefore, by making the side requiring resistance in the O-rings 12 and 13 the "reverse pressure seal" side, maintenance work such as cleaning the first valve plate 10 and replacing the O-rings 12 and 13 can be performed while maintaining the airtightness of the chamber in the "positive pressure seal" state.

[0036] As described above, the gate valve 1 (1A) of this embodiment can adjust the opening / closing angle of the arm 44 by controlling the air piston 29, thereby changing the position of the stopper pin 30 in three stages. This makes it possible to switch the position of the direction switching roller 21 within the cam groove 23 to the upper end position (center), intermediate position (upper left), intermediate position (lower left), and lower end position (right). Therefore, it is possible to accommodate four states: (A) OPEN, (B) process chamber PC side equal pressure seal, (C) process chamber PC side counter pressure seal, and (D) transfer chamber TC side positive pressure seal, and it is possible to provide strong or weak one-sided seal in the double-sided seal structure.

[0037] In the above embodiment, the stopper pin 30 of an open / close arm type controlled by the air piston 29 is used as the stopper mechanism 6. However, instead of this, the gate valve 1 (1B) may employ a rotary stopper pin 51 that is electrically or pneumatically controlled by a rotary actuator 50 as shown in FIG. 10.

[0038] The rotary actuator 50 of this embodiment is an electric rotary drive mechanism equipped with a motor 52, and an output shaft 53 of the motor 52 is fitted into and connected to a recess 55 in a piston rod 54. A piston 59 sealed with a packing 58 is provided within an enclosed space formed by attaching a rod cover 57 to a body 56, and the piston rod 54 integrated with the piston 59 is housed within the enclosed space. The piston rod 54 is biased by a spring 60, and its tip penetrates the center of the rod cover 57 and protrudes to the outside. The piston 59 divides the enclosed space into a head-side space 61 and a rod-side space 62, and a compressed air supply port 64 connected to an air pipe 63 is attached to the head-side space 61.

[0039] 19 , the stopper pin 51 is formed by bending the tip of the piston rod 54 90 degrees and forming an L-shape with contact surfaces at different heights (a first contact surface 65 at a lower position and a second contact surface 66 at a higher position). When the motor 52 is driven to rotate the output shaft 53, the piston rod 54 connected to the output shaft 53 is driven to rotate about its axis, and the stopper pin 51 at the tip of the piston rod 54 rotates integrally. In this embodiment, the upper surface of the cam plate 24 collides with the stopper pin 51, but the tip of the stopper pin 51 may be formed with a slit or a counterbore as a vibration reducing means to mitigate the impact upon collision with the cam plate 24.

[0040] The above is the structure of the gate valve 1 (1B) of this embodiment, and its operation will now be described. Figures 11 and 12 show the gate valve 1 (1B) in its fully open state, Figures 13 and 14 show the state when sealing under equal pressure, Figures 15 and 16 show the state when sealing under counter pressure, and Figures 17 and 18 show the state when sealing under positive pressure.

[0041] 11 and 12, when the gate valve 1 (1B) is not operating, the rotary actuator 50 of the stopper mechanism 6 stops the supply of compressed air from the air pipe 63, and the piston rod 54 is pressed toward the motor 52 by the spring force of the spring 60. As a result, the tip of the stopper pin 51 integrated with the piston rod 54 is retracted outward beyond the side surface of the cam plate 24. Therefore, the cam plate 24 does not collide with the tip of the stopper pin 51, the stopper function is released, and the valve rod 4 can rise to the stroke end of the air cylinder 27.

[0042] Next, as shown in FIGS. 13 and 14 , during normal operation of the gate valve 1 (1B), compressed air is supplied from the air pipe 63 to the rotary actuator 50 of the stopper mechanism 6. This causes compressed air to be supplied from the compressed air supply port 64 into the head-side space 61, pushing the piston rod 54 outward against the spring force of the spring 60. The piston 59 then strikes the inner wall surface of the rod cover 57, causing the tip of the piston rod 54 to protrude from the outer wall surface of the rod cover 57. This causes the tip of the stopper pin 51 integrated with the piston rod 54 to advance horizontally in a direction perpendicular to the stroke direction of the valve rod 4 and protrude further inward than the side surface of the cam plate 24. In addition, the motor 52 is driven to rotate the output shaft 53, and the piston rod 54 connected to the output shaft 53 is rotated about its axis, causing the stopper pin 51 to rotate to a position where the first abutment surface 65 faces vertically downward.

[0043] Here, by driving the air cylinder 26 of the drive mechanism 5, the force of compressed air pushes up the entire cam plate 24 from below, compressing the coil spring 25 and causing the valve rod 4 to rise a predetermined stroke via the cam 22 connected to the cam plate 24. Furthermore, when the fulcrum roller 19 of the rod guide 17 hits the upper end of the groove in the roller guide 20, the valve plate 3 (10, 11) moves to a height position corresponding to the openings 7, 8.

[0044] Then, the direction switching roller 21 starts to move along the cam groove 23, starting the sealing operation. At this time, the upper surface of the cam plate 24 collides with and catches the first abutment surface 65 of the stopper pin 51, causing the direction switching roller 21 to move to the middle position (left side) of the cam groove 23 and tilting the valve rod 4 to the right. As a result, the first valve plate 10 comes into contact with the first opening 7, sealing the first opening 7 and completing the sealing operation. This is the "same pressure seal" operation.

[0045] Next, as shown in Figures 15 and 16, during maintenance inside the process chamber PC, the motor 52 is driven to rotate the output shaft 53, the piston rod 54 connected to the output shaft 53 is driven to rotate about its axis, and the stopper pin 51 rotates to a position where the first abutment surface 65 is oriented 90 degrees sideways and the second abutment surface 66 is oriented vertically downward.

[0046] At this point, the direction switching roller 21 moves along the cam groove 23 and begins the sealing operation. At this time, the upper surface of the cam plate 24 collides with the second abutment surface 66 of the stopper pin 51, and the direction switching roller 21 moves from the middle position (left side) of the cam groove 23 to a position slightly lower, tilting the valve rod 4 further to the right. As a result, the first valve plate 10 is brought into contact with the first opening 7 with a stronger force than before, sealing the first opening 7 and completing the sealing operation. This is the "counter pressure sealing" operation. In this way, by varying the height position of the stopper pin 51, the strength of the pressing force of the first valve plate 10 during equal pressure sealing and counter pressure sealing can be varied depending on the height position of the direction switching roller 21.

[0047] 17 and 18, during maintenance of the gate valve 1 (1B), the supply of compressed air from the air pipe 63 to the rotary actuator 50 of the stopper mechanism 6 is stopped. This causes the piston rod 54 to elastically return to its original position due to the spring force of the spring 60, and the piston rod 54 returns to its pressed position toward the motor 52. As a result, the tip of the stopper pin 51 integrated with the piston rod 54 moves horizontally, and returns to its retracted position outside the side surface of the cam plate 24.

[0048] When the air cylinder 26 is driven, the entire cam plate 24 is pushed up from below by the force of compressed air, compressing the coil spring 25 and causing the valve rod 4 to rise a predetermined stroke via the cam 22 connected to the cam plate 24. At this time, the cam plate 24 does not collide with the tip of the stopper pin 51, and the restriction on the valve rod 4 is released, so the valve rod 4 rises to the stroke end of the air cylinder 26. At this time, the direction switching roller 21 begins to move along the cam groove 23 and initiates a sealing operation. At this time, the direction switching roller 21 moves to the lower end position (right side) of the cam groove 23, tilting the valve rod 4 to the left. This causes the second valve plate 11 to come into contact with the second opening 8, sealing the second opening 8 and completing the sealing operation. This is the "positive pressure sealing" operation.

[0049] As described above, the gate valve 1 (1B) of this embodiment can change the position of the stopper pin 51 in three stages by driving the motor 52 under electrical control of the rotary actuator 50 to adjust the rotation angle of the piston rod 54. This makes it possible to switch the position of the direction switching roller 21 within the cam groove 23 to the upper end position (center), intermediate position (upper left side), intermediate position (lower left side), and lower end position (right side). Therefore, it can accommodate four states: (A) OPEN, (B) process chamber PC side equal pressure seal, (C) process chamber PC side counter pressure seal, and (D) transfer chamber TC side positive pressure seal, and it is possible to provide strong or weak one-sided sealing in the double-sided seal structure.

[0050] In the above-described embodiment, the rotary actuator 50 is an electrically operated rotary drive mechanism. However, as shown in FIG. 20 , a pneumatic rotary drive mechanism may be employed instead. This rotary actuator 50 includes a rotary shaft 68 housed within a housing 67, and the interior space of the housing 67 is divided into two chambers by a vane 69 integrated with the rotary shaft 68. When compressed air is supplied into the chamber through one air intake / exhaust port 70 and exhausted to the outside through the other air intake / exhaust port 71, the vane 69, pushed by the compressed air, rotates while sealing the inner wall of the housing 67. This causes the piston rod 54 connected to the rotary shaft 68 to rotate about its axis, and the stopper pin 51 at the tip of the piston rod 54 rotates integrally. In this way, the rotary actuator 50 can be pneumatically controlled to adjust the rotation angle of the piston rod 54 and change the position of the stopper pin 51 in three stages, similar to the electric control shown in FIG. 19 .

[0051] PC: Process chamber TC: Transfer chamber 1: Gate valve 2: Valve body 3: Valve plate 4: Valve rod 5: Drive mechanism 6: Stopper mechanism 7: First opening 8: Second opening 9: Indoor space 10: First valve plate 11: Second valve plate 12: O-ring 13: O-ring 14: Bolt 15: Maintenance flange 16: Bonnet flange 17: Rod guide 18: Bellows 19: Fulcrum roller 20: Roller guide 21: Direction switching roller 22: Cam 23: Cam groove 24: Cam plate 25: Coil spring 26: Air cylinder 27: Rod 28: Load-bearing roller 29: Air piston 30: Stopper pin 31: Piston rod 32: Cylinder 33: Rod cover 34: Packing 35: Piston 36: Spring 37: Head-side space 38: Rod-side space 39: Air pipe 40: Compressed air supply port 41: First contact surface 42: Second contact surface 43: Joint 44: Arm 45: Joint 50: Rotary actuator 51: Stopper pin 52: Motor 53: Output shaft 54: Piston rod 55: Recess 56: Body 57: Rod cover 58: Packing 59: Piston 60: Spring 61: Head side space 62: Rod side space 63: Air pipe 64: Compressed air supply port 65: First contact surface 66: Second contact surface 67: Housing 68: Rotating shaft 69: Vane 70: Intake / exhaust port 71: Intake / exhaust port

Claims

1. A gate valve that opens and closes openings provided on both side surfaces of a valve box with a valve plate disposed inside the valve box, comprising: a valve rod coupled to the valve plate and supported so as to be able to move up and down and tilt inside the valve box; a drive mechanism provided outside the valve box for moving the valve rod up and down and tilting it by a predetermined stroke; and a stopper mechanism provided midway through the stroke of the drive mechanism for regulating or releasing the upward movement of the valve rod by supplying or stopping compressed air, wherein the stopper mechanism changes the tilt angle of the valve rod by varying the height position of the drive mechanism for tilting the valve rod, so as to impart the strength of the pressing force of the valve plate.

2. The gate valve according to claim 1, wherein the stopper mechanism has a structure in which a stopper pin moves forward or backward in a horizontal direction orthogonal to the stroke direction of the valve rod to regulate or release the upward movement of the valve rod.

3. The gate valve according to claim 2, wherein the stopper mechanism has a structure in which the opening and closing angle of an arm is adjusted by controlling an air piston to vary the height position of a stopper pin at the tip of the arm.

4. The gate valve according to claim 2, wherein the stopper mechanism has a structure in which the rotation angle of a piston rod is adjusted by controlling a rotary actuator to vary the height position of a stopper pin at the tip of the piston rod.

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