Gate valve

Abstract

A gate valve is provided that suppresses gas leakage 30 and also suppresses particle generation. [Solution] A gate valve 100 comprises an on-off valve 130 that controls the flow of gas 30, a valve rod 128 for opening and closing operations, and a drive mechanism 170 that moves the valve rod 128 to open and close the on-off valve 130, wherein the opening and closing operation of the on-off valve 130 is performed by changing the inclination between the valve rod 128 and the valve seat 140, Fluororubber is used as the sealing material 134. The surface 142 of the valve seat 140 has a bumpy shape 150 with numerous recesses 154 and recessed bottom points 158, and the height L1 from the recessed bottom point 158 ​​to the convex vertex 154 of the bumpy shape 150 is set to 1 μm or more and 10 μm or less. A gate valve 100 characterized by the following features.

Description

Technical Field

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[0001] The present invention relates to a gate valve for controlling the flow of a gas supplied to a manufacturing apparatus, such as a semiconductor manufacturing apparatus.

Background Art

[0002] The gate valve is provided with an on-off valve for controlling the flow of the supplied gas. The on-off valve has a valve seat in which an opening for flowing the gas is formed, and a valve body that closes the flow of the gas in the opening by adhering to the valve seat. A sealing material is provided on the valve body, and in the closed state of the on-off valve, the sealing material adheres to the valve seat to block the flow of the gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] <00000Z7>The gate valve targeted by the present invention is used to control the supply of a gas used in a manufacturing process. In the manufacturing process, precision equipment, such as semiconductors, is often manufactured, and it is required to prevent leakage of the supplied gas and suppress the inclusion of foreign matter. In this specification, the term "precision equipment" is used in a meaning that includes not only large equipment but also fine devices such as semiconductor chips.

[0005] The control accuracy of gas supply to gate valves significantly impacts the quality of manufactured precision equipment, such as semiconductor chips. Furthermore, the amount of gas supplied per unit time is often high, and the pressure of the supplied gas is frequently high. Moreover, the pressure at the destination of the gas supply is often high. When the gate valve is closed, it is not only necessary to prevent high-pressure supplied gas from leaking into the downstream manufacturing process, but also, in many cases, to prevent high-pressure gas present downstream from leaking upstream.

[0006] Conventionally, on-off valves have been used to control the flow of gas. Patent Document 1 discloses an on-off valve used in a microvalve, which controls the flow of very small amounts of gas, rather than an on-off valve used in a gate valve. This microvalve is a device that controls the flow of extremely small amounts of gas. The shape of the on-off valve for fluid control is very small, and it is structured in such a way that it will break if large pressure is applied. It is considered difficult to apply the microvalve technology described in Patent Document 1 to a gate valve, and conversely, it is considered difficult to apply the technology applied to gate valves to the microvalve described in Patent Document 1.

[0007] In the on-off valve described in Patent Document 1, since it controls the flow of a very small amount of gas, multiple protrusions 4a are provided on the valve seat 3 or valve body 4, or both, that constitute the on-off valve. As described above, in a microvalve, the flow rate of the gas to be controlled is very small, and the pressure applied is also very small. For this reason, the on-off valve itself in a microvalve is very small, and the structure of the valve seat and valve body that constitute the on-off valve provided in the microvalve is very simple. As described above, the microvalve described in Patent Document 1 has an extremely small size and small amount of supplied gas pressure and supply volume compared to a gate valve, making it difficult to apply microvalve technology to a gate valve.

[0008] Patent Document 2 discloses a technique for polishing the surface of a valve seat used in gate valves. This differs significantly from the view of microvalves described in Patent Document 1, as it is desirable to eliminate irregularities on the valve seat surface as much as possible, and the patent document discloses a technique for polishing to achieve this. Patent Document 3 states that it is necessary to eliminate irregularities on the valve seat surface as much as possible in order to minimize the generation of particles that lead to a deterioration in the quality of manufactured products.

[0009] The object of the present invention is to provide a gate valve that can prevent leakage of the controlled gas and suppress the generation of particles by the sealing material provided on the valve body. [Means for solving the problem]

[0010] [First Invention] The first invention is, It comprises an on-off valve for controlling the flow of gas, a valve rod for opening and closing the on-off valve, and a drive mechanism for opening and closing the on-off valve by moving the valve rod. The aforementioned on-off valve comprises a valve seat provided on the outside of an opening for gas to flow, and a valve body equipped with a sealing material that is in close contact with the valve seat to close the on-off valve. In a gate valve in which the valve body is fixed to one side of the valve rod and the opening and closing operation of the on / off valve is performed by the drive mechanism, The aforementioned sealing material is made of rubber, On the surface of the valve seat, an uneven shape is formed in which a large number of convex vertices and concave bottoms are alternately provided in the direction along the outer circumference of the opening. The vertex of the convex portion is given a curved shape, The height L1 from the bottom of the recess to the top of the protrusion in the aforementioned uneven shape is set to be 1 μm or more and 10 μm or less. This is a gate valve characterized by the following features.

[0011] [Second Invention] The second invention relates to the gate valve of the first invention, The on / off valve increases the inclination of the long axis of the valve rod relative to the reference long axis which is set parallel to the surface of the valve seat, so that the sealing material adheres closely to the surface of the valve seat, and decreases the inclination of the long axis of the valve rod relative to the reference long axis, so that the sealing material that was adhered closely to the surface of the valve seat separates from the surface of the valve seat. The aforementioned opening has a rectangular shape, The numerous vertices of the protrusions and the bottom points of the recesses of the uneven shape formed on the surface of the valve seat are formed so as to be parallel to each side forming the outer circumference of the rectangular opening. This is a gate valve characterized by the following features.

[0012] [The third invention] The third invention is the gate valve of the second invention, The distance L2 between the bottom points of the recesses on both sides of each vertex of the convex portion that forms the uneven shape of the surface of the valve seat is 10 μm or more and 100 μm or less in length. This is a gate valve characterized by the following features.

[0013] [Fourth Invention] The fourth invention is the gate valve of the third invention, The aforementioned sealing material is made of fluororubber. The height L1 from the bottom of the recess to the top of the protrusion in the aforementioned uneven shape is set to 1 μm or more and 5 μm or less. This is a gate valve characterized by the following features.

[0014] [The fifth invention] The fifth invention is the gate valve of the fourth invention, The distance L2 between the bottom points of the recesses on both sides of each of the vertices of the protrusions forming the aforementioned uneven shape is 30 μm or more and 60 μm or less in length. This is a gate valve characterized by the following features.

[0015] [The sixth invention] The sixth invention is a gate valve of the fifth invention, In the fully closed state of the on-off valve, the number of the convex portion vertices in the concavo-convex shape existing within the contact width between the surface of the valve seat and the sealing material in the direction perpendicular to the outer periphery of the opening is more than 35. A gate valve characterized by this.

Effect of the Invention

[0016] According to the present invention, it is possible to obtain a gate valve capable of maintaining the airtightness between the valve body having a sealing material and the valve seat for a longer period of time, and further suppressing the generation of particles by the sealing material.

Brief Description of the Drawings

[0017] [Figure 1] It is an explanatory diagram for explaining an open valve state of an embodiment of a gate valve to which the present invention is applied. [Figure 2] It is an explanatory diagram for explaining a closed valve state of the gate valve described in FIG. 1. [Figure 3] It is an explanatory diagram for explaining a state between a sealing material and a valve seat in a closed valve state of an on-off valve of the gate valve described in FIG. 1. [Figure 4A] [[ID=?]] [Figure 4B] It is an explanatory diagram for explaining a relationship between a valve seat and a valve body in a closed valve state of an on-off valve. [Figure 5] It is a partially enlarged view for explaining an uneven shape of a surface of a valve seat in a closed valve state of an on-off valve. [Figure 6] It is an explanatory diagram for explaining a state in which a sealing material of a valve body is in close contact with a valve seat in a closed valve state of an on-off valve. [Figure 7A] It is an explanatory diagram for explaining an action of preventing gas leakage when the valve is closed in this embodiment. [Figure 7B] It is an explanatory diagram for explaining an action and effect of an uneven shape provided on a valve seat surface. [Figure 8] It is an explanatory diagram for explaining a state of gas leakage in a conventional gate valve. [Modes for carrying out the invention]

[0018] [Introduction] In the following description of the embodiments of the gate valve 100, components with the same reference numerals have essentially the same structure, perform similar functions, and produce nearly identical effects. To avoid redundant explanations, descriptions of components with the same reference numerals may be omitted.

[0019] 1. Problems to be addressed by the gate valve 100 in the embodiment to which the invention is applied. An embodiment of a gate valve 100 for controlling the flow of gas to which the invention is applied will be described using Figures 1 and 2.

[0020] The gate valve 100 is used to control the supply of gas to manufacturing equipment, such as semiconductor manufacturing equipment. The supply control of the gas 30 to be controlled is significantly different from the supply control of liquids or powders. When the on-off valve 130 is closed, the gas 30 is much more prone to leakage than liquids or powders. For this reason, the concepts of on-off valve control technology applied to the control of liquid flow cannot be applied. To explain with a specific example, when the gate valve 100 is closed, maintaining airtightness between the valve seat 140 and the sealing material 134 of the valve body 132 that constitute the on-off valve 130 is a major challenge. The gas to be controlled has molecules that are much smaller than the molecules and particles that constitute liquids or powders, and it has almost no viscosity. For this reason, even through extremely narrow gaps, the gas 30 can easily leak out. Maintaining good airtightness between the sealing material 134 provided on the valve body 132 that constitutes the on-off valve 130 and the valve seat 140 for long-term use is an important challenge that needs to be solved.

[0021] Furthermore, the gas 30 whose flow is controlled by the gate valve 100 is often supplied at a high pressure PA from a source not shown in the illustration. Conversely, the supplied gas 30 may have a low pressure, but the downstream equipment not shown in the illustration is often filled with gas at a high pressure PA. It is required that these high-pressure gas flows from the upstream or downstream sides be completely blocked when the on-off valve 130 is closed. To overcome the pressure PA of these gases and completely block their flow, it is necessary to press the seal material 134 of the valve body 132 against the valve seat 140 with a pressure even higher than pressure PA to completely block the gas flow. To maintain airtightness between the seal material 134 and the valve seat 140 over a long period of time, for example, the pressure of the seal material 134 against the valve seat 140 can be made much higher than the gas pressure PA to block the gas flow. However, simply increasing the pressure of the seal material 134 against the valve seat 140 presents new challenges. In other words, a large load is placed on the sealing material 134, and a large amount of particles are generated from the sealing material 134. If the gas 30 containing particles is supplied to the manufacturing equipment of precision instruments such as semiconductor manufacturing equipment, which is the recipient of the gas 30 from the gate valve 100, it will cause serious problems such as a significant decrease in the quality of the products in the manufacturing process.

[0022] In other words, if the configuration is such that the pressure of the seal material 134 against the valve seat 140 is greatly increased, gas leakage when the valve is closed can be suppressed, but the seal material 134 becomes more susceptible to damage, and a problem arises in which a large amount of very fine particles are generated due to the damage to the seal material 134. In this embodiment, the seal material 134 provided on the valve body 132 is made of rubber. When good properties are required, fluororubber, which has excellent properties among rubber materials, is used as the material. When fluororubber is used as the material, not only are it excellent in heat resistance and mineral oil resistance, but also excellent properties such as low permanent deformation under compression can be obtained. However, if the pressure of the seal material 134 against the valve seat 140 is very high and the on / off valve 130 is used for a long time, even if the seal material 340 is made of rubber, especially fluororubber, a problem of particle generation will occur. In order to suppress the generation of these particles as much as possible, it is desirable to keep the pressure of the seal material 134 against the valve seat 140 as low as possible. That is, it is desirable to be able to use it with a pressure as close as possible to the pressure PA, which is the pressure of the gas mentioned above. The on-off valve 130 provided in the gate valve 100 of this embodiment, as described below, can reduce the pressure of the sealing material 134 against the valve seat 140, in other words, it can be brought closer to the pressure PA of the gas 30 compared to the conventional gate valve 100, and gas leakage can be suppressed in this state. That is, the burden on the sealing material 134 can be further reduced, and the on-off valve 130 has the effect of sufficiently suppressing gas leakage when it is closed. As described above, when discussing the pressure of the sealing material 134 on the valve seat 140 of the valve body 132 and the suppression of gas leakage, it is necessary to consider the pressure of the gas 30 or the pressure of the gas downstream, whichever is higher. In this embodiment, the explanation is based on the pressure PA of the gas 30, but the same effect is obtained even when the pressure of the gas downstream is high.

[0023] 2. Basic configuration of gate valve 100 Figures 1 and 2 show the basic configuration of a gate valve 100 to which the present invention is applied. Figure 1 shows the open state of the on-off valve 130, and Figure 2 shows the closed state of the on-off valve 130. The gate valve 100 shown in Figures 1 and 2 is used to supply or stop the supply of gas 30, which is sent at pressure PA from a supply source (not shown), to a semiconductor manufacturing apparatus or the like, which is the supply destination.

[0024] The gate valve 100 described in the embodiment has as its basic configuration a valve mechanism 110 equipped with an on-off valve 130, a valve rod 128 for opening and closing the on-off valve 130, and a drive mechanism 170 for moving the valve rod 128 to perform the opening and closing operation. A movement control roller 192 is provided on the valve rod 128, and the position of the valve body 132 in the open and closed states is controlled by the movement control roller 192 and the movement control groove 194. In addition, an on-off cam 174 moved by a piston 172 shown in Figure 2 performs the action of bringing the sealing material 134 provided on the valve body 132 into contact with the valve seat 140 and the action of separating the sealing material 134 from the valve seat 140. Through the interaction between the movement control groove 194 and the movement control roller 192, control is performed to maintain the valve body 132 in a position facing the first opening 114, and to maintain the valve body 132 in a retracted position in the open state.

[0025] 2.1 Closing operation of gate valve 100 Figure 1 shows the positional relationship between the first opening 114 and the valve body 132 of the on-off valve 130 provided on the gate valve 100 when it is in the open state. Control fluid is supplied to the cylinder 171, which constitutes the drive mechanism 170, from a control device (not shown), and the piston 172 is positioned furthest to the other direction B relative to the cylinder 171, and as a result the valve body 132 is held in the retraction space 122. The valve rod 128, which is connected to the piston 172 via the on-off cam mechanism 174, is also positioned furthest to the other direction B. A movable control roller 192 provided on the valve rod 128 is in contact with the opening end 195 located furthest to the other side of the movable control groove 194, as shown in Figure 1. The movement of the movable control roller 192 in the other direction B is blocked by the opening end 195, thereby setting the position of the valve rod 128 when the on-off valve 130 is in the open state. The first opening 114 and the second opening 116 are in an open state, and high-pressure gas 30 supplied from a source (not shown) flows through the first opening 114 formed in the valve body 112 to the second opening 116, and is then sent to a manufacturing apparatus (not shown).

[0026] When an opening / closing control device (not shown) receives a command to close the valve from a manufacturing device located downstream, a control fluid is supplied to the cylinder 171 constituting the drive mechanism 170 shown in Figure 2 by a control signal from the opening / closing control device, causing the piston 172 of the drive mechanism 170 to move in one direction A. The movement of the piston 172 is transmitted to the valve rod 128 via the opening / closing cam mechanism 174, causing the valve body 132, provided at one end 124 of the valve rod 128, to move in one direction A. A movement control roller 192 provided on the valve rod 128 moves in one direction A within the movement control groove 194. When the valve body 132 has moved to a position facing the first opening 114 formed in the valve casing body 112 of the valve mechanism 110, the movement control roller 192 provided on the valve rod 128 comes into contact with the closed valve end 196 where the movement control groove 194 is formed, preventing the valve rod 128 from moving in one direction A.

[0027] Even after the movement control roller 192 contacts the closed valve end 196 of the movement control groove 194, the piston 172 of the drive mechanism 170 moves further in direction A. This movement compresses the spring 182 of the opening / closing cam mechanism 174's opening / closing cam 175, and in this state, the opening / closing roller 178 provided on the other end 126 of the valve rod 128 moves along the opening / closing groove 176 towards the closed valve end 179. The closed valve end 179 is located in direction C on the other end 126, and the other end 126 of the valve rod 128 moves in direction C. In this state, the movement control roller 192 provided on the valve rod 128 acts as a fulcrum, and as the opening / closing roller 178 provided on the other end 126 moves in direction C, the valve body 132 provided on the one end 124 of the valve rod 128 moves in direction D. As a result, the sealing material 134 provided on the valve body 132 presses against the valve seat 140. As a result of this operation, the entire valve seat 140, which is provided on the outside of the first opening 114 so as to surround the first opening 114, comes into close contact with the sealing material 134 of the valve body 132, and the on-off valve 130 enters the closed state as shown in Figure 2.

[0028] 2.2 Opening operation of gate valve 100 Next, we will explain the opening operation of the on-off valve 130, which moves from the closed state shown in Figure 2 to the open state shown in Figure 1. In the closing operation, the on-off control device (not shown) supplies the drive fluid to the on-off control side of the cylinder 171 of the drive mechanism 170. As a result, the piston 172, which protrudes significantly from the cylinder 171 in direction A, begins to move in the other direction, direction B. Due to this movement, the on-off cam 175 of the on-off cam mechanism 174 first moves in direction B. Due to the action of the spring 182, the movement of the valve rod 128 in direction B is slightly delayed, and the on-off roller 178 moves in direction C along the on-off groove 176 before the on-off roller 178 begins to move. That is, the spring 182 begins to extend first, and the on-off roller 178, which is located at the other end 126 of the valve rod 128, moves from its position in direction D to direction C along the on-off groove 176. As the angle of inclination of the major axis of the valve rod 128 relative to the major axis of the gate valve 100 along directions A and B decreases from the closed state, the major axis 129 of the valve rod 128 rotates so that the angle of inclination, which is in the direction along the reference major axis 113 of the gate valve 100 along directions A and B, approaches zero. As the angle of inclination of the major axis 129 decreases, the pressure exerted by the sealing material 134 on the valve body 132 against the valve seat 140 decreases, and then the sealing material 134 separates from the valve seat 140. This opens the closed first opening 114. Furthermore, as the piston 172 of the drive mechanism 170 moves in the other direction B and enters the inside of the cylinder 171, the valve body 132 provided at one end 124 of the valve rod 128 moves in the other direction B, and finally the valve body 132 moves to the retracted position as shown in Figure 1, completing the valve opening operation. The state in which the valve body 132 is maintained in the retracted position is determined at the suction position when the piston 172 is drawn into the cylinder 171, and the position of the piston 172 relative to the cylinder 171 is controlled and maintained by the opening / closing control device, which is not shown above. Also, as described above, the movement control roller 192 provided on the valve rod 128 is maintained in contact with the opening end 195 of the movement control groove 194.

[0029] 3. Regarding the on / off valve 130 provided in the gate valve 100 3.1 Description of the configuration and operation of the on-off valve 130 in the embodiment Figure 3 shows an example of the configuration of an on-off valve 130 comprising a valve body 132 and a valve seat 140. The valve body 132 is fixed to one end 124 of the valve rod 128 with its opposing surface 135 inclined at a predetermined angle with respect to the long axis 129 of the valve rod 128. The valve body 132 comprises a sealing material 134 and a valve body 133 that fixes and holds the sealing material 134. As described above, in this embodiment, the valve rod 128 is fixed at an inclination with respect to a reference long axis 113 that is set in a direction parallel to the surface 142 of the valve seat 140. This is because, in the valve closing operation described below, the long axis 129 of the valve rod 128 is inclined with respect to the reference long axis 113, so that the entire sealing material 134 of the valve body 132 is tightly and uniformly pressed against the entire circumference of the valve seat 140.

[0030] Here, the rod's long axis 129 is the longitudinal axis of the valve rod 128, and the reference long axis 113 is an axis provided in a direction along the longitudinal direction of the valve body 112 in which the first opening 114 is formed. Importantly, the reference long axis 113 is provided in a relationship parallel to the surface 142 of the valve seat 140 surrounding the first opening 114, and is in a direction along one direction A and the other direction B. As the rod's long axis 129 of the valve rod 128 is tilted with respect to the reference long axis 113, the valve body 132 approaches the valve seat 140, and when the inclination of the rod's long axis 129 with respect to the reference long axis 113 becomes an angle θ, the surface 142 of the valve seat 140 and the opposing surface 135 of the valve body 133 become parallel, and the sealing material 134 presses against the valve seat 140 and makes a tight seal. In other words, in this state, the entire sealing material 134 is pressed against the surface 142 of the valve seat 140, which is provided over the entire outer circumference of the first opening 114, with a nearly uniform pressure, resulting in a tight seal. In Figure 3, the inner end of the contact portion 138 between the sealing material 134 and the surface 142 is shown as the inner circumferential end 136 of the contact portion, and the outer end of the contact portion 138 between the sealing material 134 and the surface 142 is shown as the outer circumferential end 137 of the contact portion. The valve body 132 is fixed to one end 124 of the valve rod 128 such that the opposing surface 135 of the valve body 133 is tilted by an angle θ with respect to the long axis 129 of the valve rod 128, so that the sealing material 134 is tightly sealed against the surface 142 of the valve seat 140 over its entire circumference when the long axis 129 of the valve rod 128 is at an angle θ with respect to the long axis 129 of the valve rod 128.

[0031] 3.2 Explanation of the relationship between the valve seat 140 of the on / off valve 130 and the sealing material 134 Figure 4A shows the arrangement and shape of the first opening 114 formed in the valve body 112 and the valve seat 140 provided on its outside. The first opening 114 is a rectangle with long sides extending in directions C and D. The valve seat 140 is formed outside the outer circumference 115 of the first opening 114, surrounding the first opening 114 with approximately the same width. The width of the valve seat 140 is, for example, 5 mm or more, or 10 mm or more, and varies depending on the amount of gas 30 to be controlled, etc. Figure 4B shows the closed state of the on-off valve 130. To explain the positional relationship between the sealing material 134 and the valve seat 140, the left half of the valve body 132 is removed in the diagram. The valve seat 140 is provided around the entire circumference outside the outer circumference 115 of the rectangular first opening 114. The sealing material 134 has a rectangular shape corresponding to the rectangular shape of the valve seat 140, and is configured to adhere tightly with uniform pressure around the entire circumference of the valve seat 140. The valve rod 128 is located on the back side of the valve body 133 of the valve body 132, and the sealing material 134 is provided on the front side of the valve body 133 of the valve body 132. A partially enlarged view of the AA section of Figure 4A is shown in Figure 5, and a partially enlarged view of the B-B section of Figure 4B is shown in Figure 6.

[0032] 4. Shape and function of the surface 142 of the valve seat 140 Figure 5 is a partially enlarged view of the A-A cross-section in Figure 4A. In conventional gate valve designs, the idea was that the surface 142 of the valve seat 140, i.e., the valve body side of the valve seat 140, should be as flat and smooth as possible. One reason for this is that flattening the surface 142 suppresses particle generation. However, in addition to flattening the surface 142 of the valve seat 140, it is important to consider the effect of the internal pressure of the sealing material 134 when considering particle generation. Increasing the pressure of the sealing material 134 against the valve seat 140 increases the internal pressure of the sealing material 134. If the surface 142 of the valve seat 140 is made flat as in the conventional design, the gas 30 in the closed state of the on-off valve 130 has a much more easily leaking characteristic compared to this embodiment. Furthermore, the gas 30 supplied from a source not shown is often at a high pressure. When the pressure of the gas 30 is high, leakage of the gas 30 in the closed state becomes more likely. As will be explained below, this embodiment has the effect of effectively suppressing leakage of gas 30 even when the pressure of gas 30 is high.

[0033] In the closed state of the on-off valve 130 shown in Figure 3, a differential pressure between the supplied gas 30 and the downstream gas is applied between the inner circumferential end 136 and the outer circumferential end 137 of the sealing portion 138 between the seal material 134 and the valve seat 140. Hereafter, we will assume that the pressure acting on the sealing portion 138 between the seal material 134 and the valve seat 140 is pressure PA. That is, we will explain the state in which the sealing width L4 of the sealing portion 138 shown in Figure 3 blocks the gas acting on it with a pressure of the magnitude PA, thereby preventing leakage. In Figure 3, we will assume that the pressure of the gas 30 applied to the inner circumferential end 136 of the sealing portion 138 is pressure PA, and that the pressure acting on the outer circumferential end 137 of the sealing portion 138 is zero.

[0034] When the pressure PA of the gas 30 is high, it is natural that leakage is more likely to occur when the on-off valve 130 is closed. For this reason, in conventional gate valves, in the closed state, the seal material 134 is pressed against the surface 142 of the valve seat 140 with a pressure several times higher than the pressure PA applied to the gas 30. As a result, the internal pressure of the seal material 134 increases, leading to a decrease in the elastic properties of the seal material 134. Furthermore, in the gate valve 100 shown in this embodiment, inclined to bring the seal material 134 into close contact with the valve seat 140, the long axis 129 of the valve rod 128 is inclined with respect to the reference long axis 113 during the closing operation, thereby bringing the seal material 134 into close contact with the surface 142 of the valve seat 140 and pressing it. In this configuration of the gate valve 100, when the sealing material 134 makes contact with the valve seat 140, a shearing motion occurs at the contact surface between the surface 142 of the valve seat 140 and the sealing material 134. In other words, a state of friction occurs between the sealing material 134 and the surface 142. In this frictional state, the internal pressure of the sealing material 134 is greatly related to the generation of particles. From this viewpoint, reducing the internal pressure of the sealing material 134 as much as possible has a great effect in suppressing the generation of particles.

[0035] As a result of various studies and experiments conducted by the inventors, it was found that if the pressure of the sealing material 134 on the valve seat 140 can be reduced, even if the surface 142 of the valve seat 140 is not flat, i.e., even if it has irregularities, particle generation can be efficiently suppressed if certain conditions are met. A partially enlarged view of the surface 142 of the valve seat 140 in this embodiment is shown in Figure 5. The surface 142 of the valve seat 140 has an irregular shape 150 formed along the outer circumference 115 of the first opening 114, with a number of convex vertices 154 and a number of concave bottoms 158 alternating in a direction parallel to the outer circumference 115. It was found that this irregular shape 150 makes it possible to prevent leakage of gas 30 and suppress particle generation even when the pressure of the sealing material 134 on the valve seat 140 is greatly reduced in the direction of approaching the pressure PA of the gas 30.

[0036] 5. Effects of the uneven surface 150 formed on the surface 142 of the valve seat 140. 5.1 Regarding gas leakage when conventional gate valves are closed Figure 8 shows a partial cross-sectional view of the on-off valve 130A of a conventional gate valve. Unlike the embodiment described above, the surface 142A of the valve seat 140A of the conventionally used on-off valve 130A is a flat surface formed to eliminate irregularities as much as possible. In order to prevent leakage of gas 30 from the contact area between the seal material 134A and the valve seat 140A, the seal material 134A is pressed against the surface 142A of the valve seat 140A with great pressure, and this great pressure causes the seal material 134A to be in close contact with the surface 142A of the valve seat 140A with a contact width L4. Now, assuming that the pressure applied to the gas 30 is pressure PA, and that there is no gas pressure downstream, the pressure PA of the gas 30 will be applied between the inner circumferential end 136A and the outer circumferential end 137A of the contact portion 138A. Most of the contact portion 138A is in normal contact and is shown as the normal portion 202A in the figure. In the normal section 202A, there is no gas leakage, and the pressure PA of the gas 30 is adequately counteracted. However, in the sealed section 138A, in conventional gate valves, the seal is made between the smooth surface 142A of the seal material 134A and the smooth surface 142A of the valve seat 140A, and leakage is prevented by the surface-to-surface contact against the pressure PA of the gas 30. What must be considered further here is that the substance being sealed is a gas. Gas molecules are small and have almost no viscosity. Therefore, if a small gap is formed at the contact surface between the smooth surface 142A of the valve seat 140A and the smooth surface of the seal material 134A, which is the configuration of a conventional gate valve, gas 30 can enter into this gap and strongly cause it to grow. In the conventional contact structure between the smooth surface 142A of the valve seat 140A and the smooth surface of the seal material 134A, the effect of suppressing the expansion of the above gap is very small. Therefore, there is a problem in that the above gap grows and expands rapidly. As the gap widens, the corresponding length of the contact area facing the pressure PA of the gas 30 decreases, resulting in a large pressure being applied to the short contact area. This accelerates the widening of the gap. As a result, a gap is formed, as shown as the abnormal part 204A in Figure 8, causing the gas 30 to leak.

[0037] In conventional gate valves, the pressure of the seal material 134A against the valve seat 140A was increased to prevent the aforementioned gap from widening. However, this was insufficient, and conversely, in order to suppress the growth of the abnormal portion 204A, the pressure PA of the seal material 134A against the valve seat 140A was increased to a very high level, which increased the internal pressure of the seal material 134, resulting in a major problem where particles were more easily generated from the seal material 134A. Furthermore, as mentioned above, in gate valves with a structure in which the seal material 134A is inclined with respect to the reference long axis 113 to bring it into close contact with the surface 142A of the valve seat 140, a slight misalignment occurs between the seal material 134A and the surface 142A of the valve seat 140A, which further exacerbates the problem of particle generation.

[0038] 5.2 Measures to suppress gas leakage and particle generation in this embodiment 5.2.1 Basic configuration for preventing gas leaks Figure 5 is an enlarged view of the AA section of Figure 4A, and Figure 6 is an enlarged view of the BB section of Figure 4B. The surface 142 of the valve seat 140 has a textured surface 150 consisting of rows of alternating protrusions 152 and recesses 156 arranged parallel to the outer circumference 115 of the first opening 114. It is desirable that the contact width L4 between the valve seat 140 and the sealing material 134 shown in Figure 3 has rows of textures with at least 20 or more protrusions 152, and it is even more desirable to have 35 or more protrusions. If the number of these protrusions 152 is only a few or 10 or less, there is almost no effect.

[0039] As described above, in the on-off valve 130 of this embodiment, a phenomenon occurs where the surface 142 of the valve seat 140 and the sealing material 134 rub against each other, albeit very slightly, during opening and closing. Numerous rows of irregularities are formed on the surface 142 of the valve seat 140 in a direction perpendicular to the direction of this rubbing. The conditions revealed by the experiments described below, which show the suppression effect of gas leakage and particle generation when the on-off valve 130 is closed, are that the height L1 of the convex vertex 154 is in the range of 1 μm to 10 μm, and in particular, a very good effect was obtained when the height L1 is in the range of 1 μm to 5 μm. The same applies to the distance L2 between the bottom point 158 ​​of a recess and the next bottom point 158, but a good effect was obtained in the range of 10 μm to 100 μm, and in particular, a very good effect was obtained when the distance L2 was in the range of 30 μm to 60 μm.

[0040] 5.2.2 Experiments conducted to determine the conditions In order to determine the range of the above-mentioned favorable conditions, an experiment was conducted using a sealing material 134 made of rubber material, a gas 30 at a predetermined pressure PA, and repeatedly closing and opening the on-off valve 130 with a predetermined pressing pressure higher than the pressure PA of the gas 30. The length between the bottom of one recess 158 and the next bottom of the recess 158 was kept constant, and the height L1 of the apex 154 of the convex portion was changed little by little, and the number of operations at which gas 30 began to leak was investigated. This experiment determined the favorable range for the height L1 of the apex 154 of the convex portion. Furthermore, the same experiment was conducted again, keeping the height L1 of the apex 154 of the convex portion constant, and changing the interval L2, which is the length between the bottom of one recess 158 and the next bottom of the recess 158, little by little. These experiments confirmed the favorable range for the length between the bottom of one recess 158 and the next bottom of the recess 158. In addition to the above experiment, regarding particle generation, the state of particles adhering to the valve seat 140 was investigated after each predetermined number of opening and closing operations. As a result, good results were obtained within the range described above. The experiment was conducted by applying a pressure to press the sealant 134 against the valve seat 140 such that the sealing width L4 was 50 to 60% of the diameter of the sealant 134. Among the sealants made from rubber materials, using a sealant 134 made from fluororubber yielded more desirable results.

[0041] 5.2.3 Regarding the leakage prevention effect of gas 30 when the on-off valve 130 is in the closed state. As described above, the experiment yielded good results regarding the prevention of gas leakage 30 when the on-off valve 130 is closed. The underlying concept of the effects based on these experimental results will be explained using Figures 6, 7A, and 7B.

[0042] Figure 6 is an enlarged view showing the state of the surface 142 of the valve seat 140 and the state of the sealing material 134 in contact with the outer circumference 115 of the first opening 114 on one side. The same applies to all four sides of the outer circumference 115 of the first opening 114, and the effect is the same, so we will omit the explanation and describe only one of the four sides. Rows of protrusions 152 are arranged parallel to each side of the outer circumference 115 and are formed in a direction perpendicular to each side forming the outer circumference 115, that is, in the width direction of the valve seat 140. Each protrusion 152 in the row has a protrusion vertex 154 in the center and recessed bottom points 158 on both sides. The parallel-arranged protrusions 152 surround the first opening 114 and are provided in parallel on the outside of each side of the outer circumference 115 of the first opening 114. At the connection points of each side, the protrusions 152 having each protrusion vertex 154 and each recessed bottom point 158 ​​are connected in a circular shape as shown in Figure 4A.

[0043] In the uneven shape 150, the height of the apex 154 of the convex portion relative to the bottom point 158 ​​of the concave portion is height L1, and the distance between the bottom point 158 ​​of the concave portion 152 and the next bottom point 158 ​​is spacing L2. When the sealing material 134 is pressed against the uneven shape 150 formed on the surface 142 of the valve seat 140, numerous pressure peaks 160, each having a pressure peak 162 and a pressure low point 164, are formed on the sealing material 134 at the contact surface between the sealing material 134 and the surface 142, in a parallel arrangement surrounding the outer circumference 115 of the first opening 114. The optimal values ​​for height L1 and spacing L2 are as described above.

[0044] Figure 7A illustrates the relationship between the pressure peak 160 at the contact point 138 between the sealing material 134 and the valve seat 140 and the pressure PA of the gas 30. This explanation assumes that the gas 30 supplied to the first opening 114 is at a pressure PA higher than the gas pressure downstream of the valve 130. Note that if the gas pressure downstream of the valve 130 is higher than the gas 30 supplied to the first opening 114, the only difference is that the direction of the force is reversed; the basic concept remains exactly the same.

[0045] Pressure PA is applied to the portion of the sealing portion 138 between the inner circumferential end 136 and the outer circumferential end 137. On the other hand, in the sealing portion 138, pressure peaks 160 are connected in series, and the pressure PT, which is the sum of the pressure peaks 160, counteracts the pressure PA. In the sealing portion 138A of the conventional gate valve shown in Figure 8, the contact surface of the sealing material 134A and the contact surface of the surface 142A were flat surfaces without any irregularities, so a phenomenon occurred in which a very small gap rapidly grew due to the action of pressure PA. However, in the embodiment of the present application shown in Figure 6, the protrusion 152 is formed parallel to the outer circumference 115 of the first opening 114. As a result, a phenomenon occurs in which the growth of the gap in the direction perpendicular to the outer circumference 115 is greatly suppressed. As a result, gas 30 enters into the minute gap and the phenomenon of this minute gap growing is suppressed, and the gap does not grow.

[0046] To make the interaction of the pressure peaks 160 in Figure 7A easier to understand, we will explain it using Figure 7B. The value of pressure PT that the sealing portion 138 in Figure 7A can resist is the sum of the series values ​​of the pressure peaks 160 shown in Figure 7B. Of course, due to various reasons, the actual pressure will be lower than the sum of the series values ​​of the pressure peaks 160, but each pressure peak 160 will act more effectively and more effectively, so that the resistable pressure PT will be in line with the sum of the series values ​​of the pressure peaks 160. As a result, compared to conventional gate valves, where the pressure of the sealing material 134A against the valve seat 140A was set to a very high value considering a large safety factor relative to the pressure PA of the gas 30, the above safety factor can be reduced to an appropriate value. For example, as described above, if the valve seat 140 has 35 rows of protrusions 152 between the sealing portions 138, the pressure PA applied to both ends of the sealing portion 138, namely the inner circumferential end 136 and the outer circumferential end 137 of the sealing portion, as shown by graph A in Figure 7B, is distributed among the 35 pressure peaks 160. Although this is an ideal state, even considering various factors and safety factors, each pressure peak 162 of each pressure peak 160 operates much more efficiently than in a conventional gate valve. As a result, the pressure exerted by the sealing material 134 on the valve seat 140 can be reduced compared to a conventional gate valve. Consequently, deterioration is suppressed even when the gate valve 100 is used for extended periods. Particle generation is also greatly suppressed.

[0047] 5.2.4 Suppression of twisting of the sealing material 134 during valve closing operation As shown in Figure 6, the outer circumference 115 of the first opening 114 has a series of bumps and recesses, each of which is parallel to the outer edge, forming a bumpy shape 150 consisting of numerous protrusions 152 and numerous recesses 156. As explained using Figure 3, when the on / off valve 130 is opened and closed, the surface 142 of the valve seat 140 and the sealing material 134 rub against each other, albeit very slightly. This slight rubbing can cause partial twisting in conventional sealing materials 134A. However, in this embodiment, the occurrence of partial twisting is suppressed.

[0048] In other words, when partial twisting occurs, a gap is created at both ends of the twist in a direction perpendicular to the outer circumference 115 of the first opening 114. However, in this embodiment, a number of rows of irregularities are formed on the surface 142 of the valve seat 140 in a direction that intersects with the direction in which twisting is likely to occur at both ends of the partial twist. These numerous pressure peaks 162 and pressure valleys 164 have the effect of suppressing twisting at both ends of the partial twist of the sealing material 134 relative to the valve seat 140. As a result, it becomes difficult for twisting to occur at both ends of the partial twist, and the partial twist itself is suppressed. As a result, gas leakage due to partial twisting can be suppressed. [Explanation of symbols]

[0049] 30: Gas, 100: Gate valve, 110: Valve mechanism, 112: Valve body, 113: Reference long axis, 114: First opening, 115: Outer circumference, 116: Second opening, 120: Valve chamber, 124: One end, 126: Other end, 128: Valve rod, 129: Rod long axis, 130: On / off valve, 132: Valve body, 133: Valve body, 134: Seal material, 135: Opposing surface, 136: Inner circumferential end of sealing part, 137: Outer circumferential end of sealing part, 13 8: Contact area, 140: Valve seat, 142: Surface, 150: Uneven shape, 152: Convex part, 154: Convex apex, 156: Concave, 158: Bottom of concave part, 162: Pressure peak, 164: Pressure valley, 170: Drive mechanism, 171: Cylinder, 172: Piston, 174: Opening / closing cam mechanism, 175: Opening / closing cam, 176: Opening / closing groove, 178: Opening / closing roller, 182: Spring, 192: Movement control roller, 194: Movement control groove, 196: Closed end.

Claims

1. It comprises an on-off valve for controlling the flow of gas, a valve rod for opening and closing the on-off valve, and a drive mechanism for opening and closing the on-off valve by moving the valve rod. The aforementioned on-off valve comprises a valve seat provided on the outside of an opening for gas to flow, and a valve body equipped with a sealing material that is in close contact with the valve seat to close the on-off valve. In a gate valve in which the valve body is fixed to one side of the valve rod and the opening and closing operation of the on / off valve is performed by the drive mechanism, The aforementioned sealing material is made of rubber, On the surface of the valve seat, an uneven shape is formed in which a large number of convex vertices and concave bottoms are alternately provided in the direction along the outer circumference of the opening. The vertex of the convex portion is given a curved shape, The height L1 from the bottom of the recess to the top of the protrusion in the aforementioned uneven shape is set to be 1 μm or more and 10 μm or less. A gate valve characterized by the following features.

2. In the gate valve according to claim 1, The on / off valve increases the inclination of the long axis of the valve rod relative to the reference long axis which is set parallel to the surface of the valve seat, so that the sealing material adheres closely to the surface of the valve seat, and decreases the inclination of the long axis of the valve rod relative to the reference long axis, so that the sealing material that was adhered closely to the surface of the valve seat separates from the surface of the valve seat. The aforementioned opening has a rectangular shape, The numerous vertices of the protrusions and the bottom points of the recesses of the uneven shape formed on the surface of the valve seat are formed so as to be parallel to each side forming the outer circumference of the rectangular opening. A gate valve characterized by the following features.

3. In the gate valve according to claim 2, The distance L2 between the bottom points of the recesses on both sides of each vertex of the convex portion that forms the uneven shape of the surface of the valve seat is 10 μm or more and 100 μm or less in length. A gate valve characterized by the following features.

4. In the gate valve according to claim 3, The aforementioned sealing material is made of fluororubber. The height L1 from the bottom of the recess to the top of the protrusion in the aforementioned uneven shape is set to be 1 μm or more and 5 μm or less. A gate valve characterized by the following features.

5. In the gate valve according to claim 4, The distance L2 between the bottom points of the recesses on both sides of each of the vertices of the protrusions forming the aforementioned uneven shape is 30 μm or more and 60 μm or less in length. A gate valve characterized by the following features.

6. In the gate valve according to claim 5, In the fully closed state of the valve, the number of vertices of the protrusions in the uneven shape that exist within the contact width between the surface of the valve seat and the sealing material in a direction perpendicular to the outer circumference of the opening is greater than 35. A gate valve characterized by the following features.

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