Gate valve

Abstract

The gate valve of the present invention is configured to block a flow path. The gate valve includes a valve housing, a valve body, a rotating shaft, a rotation driving unit, a pressing driving unit, a driving pressure generating mechanism, and a non-linear operation imparting mechanism. And the pushing and pressing driving part is arranged in the valve box. The pressing drive unit is capable of moving the valve body. The pressing drive unit presses the valve body to a valve closing position. The drive pressure generating mechanism is connected to the pressing drive unit and is capable of causing the pressing drive unit to extend and retract. The non-linear operation imparting mechanism is capable of performing a linear operation and a non-linear operation on an expansion / contraction operation of the pressing drive unit driven by the drive pressure generating mechanism.

Description

Technical Field

[0001] The invention relates to a gate valve, and in particular to a technology suitable for being used in a pendulum valve. Background Art

[0002] A gate valve is provided between chambers, pipes, pumps, etc. of a vacuum device, etc. The gate valve is used to block two spaces having different vacuum degrees and connect the two blocked spaces. As such a gate valve, various types of valves are known.

[0003] The inventor has developed a gate valve capable of performing a highly reliable blocking operation and has filed a patent application (Patent Document 1). The gate valve is provided with: a valve box formed to cross a flow channel; a neutral valve portion rotatable by a rotation axis whose axis is parallel to the flow channel direction; a first movable valve portion, as a movable valve portion that can slide in the flow channel direction relative to the neutral valve portion, and can be pushed to the opening of the valve box in the flow channel for sealing; a second movable valve portion that can slide in the flow channel direction relative to the first movable valve portion; a first force-applying portion that can push the first movable valve portion to the opening for sealing operation; a second force-applying portion that can adjust the thickness of the first movable valve portion and the second movable valve portion; and a third force-applying portion that applies force to the first movable valve portion relative to the neutral valve portion.

[0004] Patent Document 1: Japanese Patent No. 6358727

[0005] The first urging portion is composed of a plurality of hydraulic drive portions. If the hydraulic drive portion protrudes due to volume expansion of the hydraulic oil caused by temperature rise in the first urging portion, there is a problem that the rotation operation of the valve plate may be affected.

[0006] In particular, if there are differences in the extension and contraction states of the plurality of hydraulic drive parts due to frictional resistance etc. generated when the hydraulic drive parts are extended and contracted, only the hydraulic drive part that is easiest to move is driven. Therefore, the protrusion amount is likely to increase. It is required to improve this problem. Summary of the invention

[0007] The present invention has been made in view of the above circumstances, and intends to achieve the following objects.

[0008] 1. Avoid the influence of temperature rise of working oil on volume expansion.

[0009] 2. Avoid deviations in the protrusion of movable parts when constructing multiple hydraulic drive parts.

[0010] 3. Avoid obstruction of the valve body's rotation operation caused by protrusion of the movable part of the hydraulic drive unit.

[0011] A gate valve according to one embodiment of the present invention is a gate valve for blocking a flow channel, comprising: a valve box, which is inserted into the flow channel and has a first opening portion and a second opening portion which are opposite to each other and communicate with each other and form the flow channel, a hollow portion located between the first opening portion and the second opening portion, and a peripheral portion located around the first opening portion; a valve body, which is located in the hollow portion and can open and close the flow channel; a rotating shaft, which supports the valve body in a manner that the valve body can rotate in a direction intersecting the flow channel between a retreat position in the hollow portion and a valve opening shielding position, and the rotating shaft has a plurality of holes extending in the direction of the flow channel. axis; a rotation drive unit capable of driving the valve body to rotate; a pushing drive unit, which is arranged in the valve box and capable of causing the valve body arranged at the valve opening shielding position to move toward a valve closing position in contact with the peripheral portion in the direction along the flow channel, the pushing drive unit pushing the valve body toward the valve closing position; a driving pressure generating mechanism, which is connected to the pushing drive unit and capable of causing the pushing drive unit to perform a telescopic action; and a nonlinear action imparting mechanism, which can realize linear action and nonlinear action on the telescopic action of the pushing drive unit driven by the driving pressure generating mechanism.

[0012] In a gate valve of one embodiment of the present invention, during the linear action of the nonlinear action imparting mechanism, the pushing drive portion can perform a linear action at a position near the valve closing position abutting against the valve body, and during the nonlinear action of the nonlinear action imparting mechanism, the pushing drive portion can perform a nonlinear action at a position separated from the valve body.

[0013] In the gate valve of one aspect of the present invention, the driving pressure generating mechanism may cause the pushing drive portion to perform nonlinear expansion and contraction motion in relation to the expansion and contraction motion of the pushing drive portion separated from the valve body during the nonlinear motion of the nonlinear motion imparting mechanism.

[0014] In a gate valve of one embodiment of the present invention, the pushing drive part may have a retraction spring, and the retraction spring retracts the pushing drive part that is extended by the increase of the driving pressure caused by the driving pressure generating mechanism, and the nonlinear action imparting mechanism may have an elastic mechanism that retracts the pushing drive part.

[0015] In the gate valve according to one aspect of the present invention, the elastic mechanism may be an elastic body having a spring constant different from that of the return spring.

[0016] In a gate valve of one embodiment of the present invention, the elastic body can be a weak spring whose elastic force is smaller than that of the retraction spring and can realize the nonlinear action, and the retraction spring can be a strong spring whose elastic force is larger than that of the elastic body and can realize the linear action.

[0017] In the gate valve according to one aspect of the present invention, the weak spring and the strong spring may be arranged in series.

[0018] In the gate valve according to one aspect of the present invention, the weak spring and the strong spring may be disposed in a dual manner at coaxial positions.

[0019] In the gate valve according to one aspect of the present invention, the nonlinear motion imparting mechanism may include a start-of-motion nonlinear mechanism capable of realizing the nonlinear motion when the push drive portion starts to extend due to the drive pressure generating mechanism.

[0020] In a gate valve of one embodiment of the present invention, the starting action nonlinear mechanism may have one of an elastic mechanism, an elastic pressure adjustment mechanism and an elastic fluid, the elastic mechanism may be arranged on a hydraulic circuit constructed by connecting the driving pressure generating mechanism and the pushing drive part, the elastic pressure adjustment mechanism may be connected to the hydraulic circuit, and the elastic fluid may be connected to the hydraulic circuit.

[0021] In the gate valve according to one aspect of the present invention, the nonlinear start mechanism may include a vacuum region, and the vacuum region may be disposed in a hydraulic circuit configured to connect the drive pressure generating mechanism and the push drive unit.

[0022] A gate valve according to one embodiment of the present invention is a gate valve for blocking a flow channel, comprising: a valve box, which is inserted into the flow channel and has a first opening portion and a second opening portion which are opposite to each other and communicate with each other and form the flow channel, a hollow portion located between the first opening portion and the second opening portion, and a peripheral portion located around the first opening portion; a valve body, which is located in the hollow portion and can open and close the flow channel; a rotating shaft, which supports the valve body in a manner that the valve body can rotate in a direction intersecting the flow channel between a retreat position in the hollow portion and a valve opening shielding position, and the rotating shaft has a plurality of holes extending in the direction of the flow channel. axis; a rotation drive unit capable of driving the valve body to rotate; a push drive unit disposed on the valve box and capable of moving the valve body disposed at the valve opening shielding position toward a valve closing position in contact with the peripheral portion in a direction along the flow channel, the push drive unit pushing the valve body toward the valve closing position; a driving pressure generating mechanism connected to the push drive unit and capable of causing the push drive unit to perform a telescopic action; and a nonlinear action imparting mechanism capable of realizing a linear action and a nonlinear action for the telescopic action of the push drive unit driven by the driving pressure generating mechanism. The valve body, for example, includes a neutral valve portion, a movable valve portion, a movable valve frame portion, and a movable valve plate portion. The push drive unit, for example, is a valve box force applying portion. The driving pressure generating mechanism, for example, is a driving unit. The telescopic action includes an extension action and a retraction action. The push drive unit includes a fixed portion and a movable portion. The movable portion can move relative to the fixed portion. The fixed portion, for example, is a cylinder. The movable portion, for example, is a piston.

[0023] According to the above structure, during the opening and closing action of the gate valve, the valve body moves along the flow channel direction between the valve opening shielding position and the valve closing position through the telescopic action of the push drive part. At this time, the nonlinear action imparting mechanism can perform a linear action of the valve body at the valve opening shielding position and a nonlinear action of adjusting the protrusion amount of the push drive part in a state of not contacting the valve body for the telescopic action of the push drive part. In other words, the nonlinear action imparting mechanism can perform such two actions by the same device (mechanism). Thus, by extending the push drive part by the nonlinear action imparting mechanism, the push drive part can smoothly push the valve body and move it to the valve closing position. Furthermore, the push drive part can be retracted by the nonlinear action imparting mechanism. Therefore, the pushing state of the push drive part on the valve body can be smoothly released, thereby performing an action of moving the valve body to the valve opening shielding position.

[0024] The nonlinear motion imparting mechanism can cause the push drive unit to perform nonlinear motion. Therefore, when the valve body is rotated between the retreat position and the valve opening shielding position, the push drive unit can maintain a state of being separated from the valve body by a sufficient distance. Therefore, the nonlinear motion imparting mechanism can prevent the push drive unit from interfering with the rotation of the valve body.

[0025] Sometimes, the force received by the portion (e.g., a sealing material or a friction surface, etc.) that is deformed or rubbed by the telescopic action of the push drive unit is relatively large. In this case, it is also possible to prevent the push drive unit from being unable to perform a smooth telescopic action. Therefore, the push drive unit can easily maintain a state of being separated from the valve body by a sufficient distance.

[0026] In addition, in the conventional design of the gate valve, as a countermeasure to avoid the occurrence of deviation in the protrusion amount of the push drive part, it is necessary to increase the thickness of the gate valve so that the push drive part and the valve body are sufficiently separated. In contrast, since the push drive part can easily maintain a state of being separated from the valve body by a sufficient distance, the thickness of the valve box will not increase. Therefore, the thickness of the gate valve can be prevented from increasing.

[0027] When the gate valve is heated, for example, the working pressure that causes the push drive unit to perform the telescopic motion is transmitted from the driving pressure generating mechanism to the working fluid (working oil) of the push drive unit, causing thermal expansion. Even when the working fluid undergoes thermal expansion, the use of a nonlinear motion imparting mechanism can prevent the push drive unit from accidentally protruding toward the valve body. Alternatively, sometimes a large force is applied to a portion (for example, a sealing material or a friction surface) that is deformed or rubbed due to the telescopic motion of the push drive unit. Even when the motion of the push drive unit is obstructed in this way, the gate valve has a nonlinear motion imparting mechanism, preventing the push drive unit from accidentally protruding toward the valve body.

[0028] Here, the linear motion and the nonlinear motion refer to whether the telescopic movement of the push drive part is a linear motion or a nonlinear motion relative to the increase and decrease of the working pressure applied to the push drive part from the driving pressure generating mechanism. Alternatively, the linear motion and the nonlinear motion refer to whether the telescopic movement of the push drive part is a linear motion or a nonlinear motion relative to the increase and decrease of the volume of the working fluid supplied and discharged from the driving pressure generating mechanism to the push drive part.

[0029] In a gate valve of one embodiment of the present invention, in the linear action of the nonlinear action imparting mechanism, the pushing drive portion can perform a linear action at a position near the valve closing position abutting against the valve body (movable valve portion), and in the nonlinear action of the nonlinear action imparting mechanism, the pushing drive portion can perform a nonlinear action at a position separated from the valve body (movable valve portion).

[0030] According to the above structure, since the gate valve has a nonlinear motion imparting mechanism, the push drive unit can approach the valve body and perform a linear motion at a position where the valve body can be pushed. Therefore, the valve body can be smoothly pushed by the extension of the push drive unit to move the valve body to the valve closing position. Furthermore, the push state of the push drive unit on the valve body can be smoothly released by the retraction of the push drive unit, and the valve body can be moved to the valve opening shielding position.

[0031] In the nonlinear motion imparting mechanism, the push drive part can perform nonlinear motion at a position where the push drive part is separated from the valve body to such an extent that the valve body can rotate. Thus, when the working fluid (working oil) that transmits the working pressure from the driving pressure generating mechanism to the push drive part undergoes thermal expansion due to heating, the phenomenon that the push drive part accidentally protrudes toward the valve body can be prevented. Alternatively, sometimes the push drive part cannot perform smooth telescopic motion due to the force received from the part (for example, a sealing material or a friction surface, etc.) that is deformed or rubbed due to the telescopic motion of the push drive part. In contrast, since the gate valve has a nonlinear motion imparting mechanism, a smooth telescopic motion of the push drive part can be achieved.

[0032] That is, by causing the push drive unit to perform nonlinear motion by the nonlinear motion imparting mechanism, the push drive unit can be smoothly operated. Furthermore, the nonlinear motion of the push drive unit can be transferred to the linear motion of the push drive unit at a position close to the valve body.

[0033] In a gate valve of one embodiment of the present invention, in the nonlinear action of the nonlinear action imparting mechanism, regarding the telescopic action of the pushing drive part in a state separated from the valve body (movable valve part), the driving pressure generating mechanism causes the pushing drive part to perform nonlinear telescopic action.

[0034] According to the above structure, during the rise and fall of the working pressure applied to the push drive unit by the driving pressure generating mechanism, the telescopic movement of the push drive unit can be linear or the telescopic movement of the push drive unit can be nonlinear. Thus, by making the push drive unit perform nonlinear movement, the movement of the push drive unit can be smoothly performed. Furthermore, it is possible to transfer from the nonlinear movement of the push drive unit to the linear movement of the push drive unit.

[0035] Here, "linear motion" means that the extension and contraction motion of the push drive part is linear in the rise and fall of the working pressure applied to the push drive part by the driving pressure generating mechanism. In addition, "non-linear motion" means that the extension and contraction motion of the push drive part is non-linear in the rise and fall of the working pressure applied to the push drive part by the driving pressure generating mechanism.

[0036] In particular, the nonlinear action refers to a state in which the push drive part does not expand or contract during the increase or decrease of the working pressure applied to the push drive part by the driving pressure generating mechanism. Alternatively, the nonlinear action refers to a state in which the expansion and contraction rate of the push drive part changes at a certain pressure relative to the rate of change of the increase or decrease of the working pressure.

[0037] In other words, in linear motion, the expansion and contraction rate of the push drive unit does not change relative to the rate of change of the working pressure. When the change of the working pressure and the expansion and contraction (stroke) of the push drive unit are plotted, the linear motion is represented by a straight line with a predetermined slope in the two-value relationship.

[0038] In addition, in nonlinear action, the expansion and contraction rate changes with respect to the rate of change of the working pressure. When the change of the working pressure and the expansion and contraction (stroke) of the push drive unit are plotted, the nonlinear action is not a straight line with a predetermined slope in the two-value relationship, but a change in slope. The nonlinear action is represented by a vertical line along the vertical axis of the two-value relationship in the graph. Alternatively, the nonlinear action is represented not only by a straight line, but also by a portion in the graph where the two-value relationship is a broken line connecting the straight lines.

[0039] In addition, the nonlinear motion mentioned here does not include nonlinear motion in the push drive portion other than that generated by the nonlinear motion imparting mechanism, such as adhesion in the push drive portion.

[0040] In a gate valve according to one aspect of the present invention, the push drive portion includes a retraction spring, the retraction spring retracts the push drive portion when the push drive portion is extended by the increase in the drive pressure caused by the drive pressure generating mechanism, and the nonlinear motion imparting mechanism includes an elastic mechanism for retracting the push drive portion. The drive pressure is, for example, a working pressure.

[0041] According to the above structure, the push drive part is extended by the increase of the driving pressure (working pressure) applied by the driving pressure generating mechanism. When the driving pressure (working pressure) decreases, the push drive part is retracted by the elastic force of the retraction spring. The push drive part can perform linear motion by the working pressure and the elastic force of the retraction spring.

[0042] In contrast, the nonlinear motion imparting mechanism is a structure independent of the retraction spring, and has an elastic mechanism that can apply elastic force in a direction to retract the push drive unit when the driving pressure (working pressure) decreases. The elastic mechanism enables the push drive unit that can perform linear motion to also perform nonlinear motion.

[0043] As the elastic mechanism, a stroke buffer spring connected to the piston of the push drive portion and capable of applying elastic force in the same direction as the retraction spring may be used. As the elastic mechanism, a stroke buffer spring capable of applying elastic force to the piston from the same side as the retraction spring in the extension direction of the piston may be used. The elastic mechanism can apply elastic force to the piston from the side opposite to the retraction spring in the extension direction of the piston.

[0044] As the elastic mechanism, a stroke buffer spring which is arranged in series with the retraction spring and can apply elastic force to the piston of the push drive unit can be adopted. Here, the stroke buffer spring which is arranged in series with the retraction spring can be connected to the piston of the push drive unit or can be separated from the piston of the push drive unit.

[0045] As the elastic mechanism, a stroke buffer spring which is arranged in parallel with the retraction spring and can apply elastic force to the piston of the push drive unit can be adopted. Here, as the stroke buffer spring arranged in parallel with the retraction spring, a double spring structure in which the retraction spring and the stroke buffer spring are in a coaxial state can be exemplified.

[0046] The elastic mechanism may have a structure capable of applying elastic force to the piston of the push drive unit via the working fluid (driving fluid) in the driving pressure generating mechanism. In this case, the elastic mechanism may have a structure connected to the piston of the push drive unit, or may have a structure not connected to the piston of the push drive unit. The elastic mechanism can apply elastic force to the piston from the side opposite to the retraction spring in the expansion and contraction direction of the piston.

[0047] When the elastic mechanism is not connected to the piston of the push drive unit, the elastic mechanism is arranged at a position on the side of the piston opposite to the retraction spring relative to the telescopic direction. The elastic mechanism can be arranged in a pipe connecting the driving pressure generating mechanism and the push drive unit.

[0048] In addition, the retraction spring may be pressurized. The retraction spring may not be pressurized. The stroke buffer spring may be pressurized. The stroke buffer spring may not be pressurized.

[0049] In the gate valve according to one aspect of the present invention, the elastic mechanism is an elastic body having a spring constant different from a spring constant of the return spring.

[0050] According to the above structure, the pushing drive part performs linear motion through the working pressure of the driving pressure generating mechanism and the elastic force of the retraction spring. The pushing drive part can perform nonlinear motion through the elastic body. Here, the pushing drive part performs linear motion at a specified expansion and contraction rate through the rise and fall of the driving pressure (working pressure) generated by the driving pressure generating mechanism and the retraction spring. On this basis, the elastic body can exert an elastic force so that the expansion and contraction rate of the pushing drive part becomes a different expansion and contraction rate from the expansion and contraction rate when the linear motion is performed only by the retraction spring. The elastic body has an elastic force that can be exerted on the piston, so that the expansion and contraction rate of the pushing drive part becomes a different expansion and contraction rate from the expansion and contraction rate when the linear motion is performed only by the retraction spring.

[0051] The elastic body is a structure independent of the retraction spring, and when the driving pressure (working pressure) decreases, the elastic body can apply an elastic force in a direction to retract the push driving part.

[0052] As the elastic body, a stroke buffer spring connected to the piston of the push drive unit and capable of applying elastic force in a direction different from that of the retraction spring can be used. As the elastic body, a stroke buffer spring capable of applying elastic force to the piston from the same side as the retraction spring in the expansion and contraction direction of the piston can be used. As the elastic body, an elastic force can be applied to the piston from the side opposite to the retraction spring in the expansion and contraction direction of the piston.

[0053] As the elastic body, a stroke buffer spring which is arranged in series with the retraction spring and can apply an elastic force to the piston of the push drive portion can be used.

[0054] As the elastic body, a stroke buffer spring which is arranged in parallel with the retraction spring and can apply elastic force to the piston of the push drive unit can be adopted. Here, as the stroke buffer spring arranged in parallel with the retraction spring, a double spring structure in which the retraction spring and the stroke buffer spring are in a coaxial state can be exemplified.

[0055] The elastic body may have a structure capable of applying elastic force to the piston of the push drive unit via the working fluid (driving fluid) in the driving pressure generating mechanism. In this case, the elastic body may have a structure connected to the piston of the push drive unit. The elastic body may also have a structure not connected to the piston of the push drive unit. The elastic body can apply elastic force to the piston from the side opposite to the retraction spring in the expansion and contraction direction of the piston.

[0056] When the elastic body is not connected to the piston of the push drive unit, the elastic body is arranged at a position on the side of the piston opposite to the retraction spring relative to the extension direction. The elastic body can be a structure arranged in a pipe connecting the driving pressure generating mechanism and the push drive unit.

[0057] The elastic body may be an elastic mechanism capable of causing the pressing drive unit to expand and contract while adjusting the driving pressure applied to the pressing drive unit from the driving pressure generating mechanism by elastic force.

[0058] In a gate valve according to one embodiment of the present invention, the elastic body is a weak spring having a smaller elastic force than the retraction spring and capable of realizing the nonlinear action, and the retraction spring is a strong spring having a larger elastic force than the elastic body and capable of realizing the linear action.

[0059] According to the above structure, the push drive unit performs linear motion by the working pressure of the drive pressure generating mechanism and the elastic force of the retraction spring. The push drive unit can perform nonlinear motion by the elastic body having an elastic force smaller than that of the retraction spring.

[0060] Since the elastic force of the elastic body is smaller than the elastic force of the retraction spring, the elastic body contracts earlier than the retraction spring due to the increase of the working pressure applied to the push drive part by the driving pressure generating mechanism, thereby performing nonlinear action. After the elastic body contracts to a predetermined length, the retraction spring contracts due to the increase of the working pressure, thereby performing linear action.

[0061] Since the elastic force of the elastic body is smaller than the elastic force of the retraction spring, the retraction spring is extended by the decrease of the working pressure applied to the push drive part by the driving pressure generating mechanism, thereby performing a linear action. After the retraction spring is extended to a predetermined length and the linear action is terminated, the elastic body is extended by the decrease of the working pressure, thereby performing a nonlinear action.

[0062] In the gate valve according to one aspect of the present invention, the weak spring and the strong spring are arranged in series.

[0063] According to the above structure, the retraction spring and the weak spring for retracting the piston of the push drive part when the push drive part retracts due to the decrease of the working pressure are arranged in series. The weak spring is retracted before the retraction spring due to the increase of the working pressure, thereby performing a nonlinear action. After the weak spring reaches a predetermined length, the retraction spring is retracted due to the increase of the working pressure, thereby performing a linear action.

[0064] Since the elastic force of the weak spring is smaller than that of the retraction spring, the retraction spring is first extended by the decrease of the working pressure, thereby performing linear action. After the retraction spring reaches a predetermined length and ends the linear action, the weak spring is extended by the decrease of the working pressure, thereby performing nonlinear action.

[0065] The weak spring may be formed as one spring connected to the strong spring. The weak spring may be formed so that the thickness of its spring material is thinner than that of the strong spring.

[0066] The weak spring can be used as a spring independent of the strong spring and arranged on the same axis as the strong spring. The weak spring and the strong spring can have the same coil diameter or different coil diameters.

[0067] In addition, as the compression spring and the weak spring arranged in series, a deformation spring structure in which the end of the compression spring is formed into a conical shape or the like and the coil diameter is changed may be adopted.

[0068] In the gate valve according to one aspect of the present invention, the weak spring and the strong spring may be disposed in a dual manner at coaxial positions.

[0069] According to the above structure, a retraction spring and a weak spring are provided in dual configuration for contracting the piston of the push drive part when the push drive part retracts due to a decrease in the working pressure. The retraction spring and the weak spring are arranged in parallel. The weak spring is expanded and contracted by a relatively small working pressure to a degree that does not cause the expansion and contraction of the retraction spring, thereby performing a nonlinear action. When the weak spring is in a state of a predetermined length, the retraction spring is expanded and contracted by a larger working pressure, thereby performing a linear action.

[0070] The weak spring can be formed so that the thickness of its spring material is thinner than that of the strong spring.

[0071] The weak spring may be a separate spring from the strong spring, having a different coil diameter than the strong spring. The weak spring may be configured to be coaxial with the strong spring and concentric with the strong spring. The weak spring may have a longer coil length than the strong spring. The weak spring and the strong spring may be a dual spring.

[0072] In the gate valve according to one aspect of the present invention, the nonlinear motion imparting mechanism includes a start-of-motion nonlinear mechanism capable of realizing the nonlinear motion when the pressing drive portion starts to extend due to the drive pressure generating mechanism.

[0073] According to the above structure, the extension and retraction movement of the push drive part can be linear in the position abutting against the valve body according to the increase and decrease of the working pressure applied to the push drive part by the driving pressure generating mechanism. In addition, the extension and retraction movement of the push drive part can be nonlinear in the position most separated from the valve body according to the increase and decrease of the working pressure applied to the push drive part by the driving pressure generating mechanism.

[0074] The nonlinear mechanism at the start of the movement can realize a nonlinear movement near the start of the extension movement. That is, the nonlinear mechanism at the start of the movement can realize a nonlinear movement near the end of the retraction movement.

[0075] By means of the nonlinear mechanism for starting the action, the push drive part can perform a nonlinear action at a position separated from the valve body and enabling the valve body to rotate. Thus, even when the gate valve is heated and the working fluid (working oil) that causes the push drive part to perform the telescopic action undergoes thermal expansion, the phenomenon of the push drive part accidentally protruding toward the valve body can be prevented. Alternatively, sometimes the push drive part cannot perform a smooth telescopic action due to the force received from the part (for example, a sealing material or a friction surface, etc.) that is deformed or rubbed due to the telescopic action of the push drive part. In contrast, since the nonlinear action imparting mechanism has a nonlinear mechanism for starting the action, a smooth telescopic action of the push drive part can be achieved.

[0076] As the nonlinear mechanism for starting the action, a stroke buffer spring connected to the piston of the push drive portion and capable of applying elastic force in the same direction as the retraction spring may be used. As the nonlinear mechanism for starting the action, a stroke buffer spring capable of applying elastic force to the piston from the same side as the retraction spring in the direction of extension and contraction of the piston may be used. The nonlinear mechanism for starting the action can apply elastic force to the piston from the side opposite to the retraction spring in the direction of extension and contraction of the piston.

[0077] As the nonlinear mechanism for starting the operation, a stroke buffer spring which is arranged in series with the retraction spring and can apply elastic force to the piston of the push drive unit can be used. The elastic force of the stroke buffer spring can be smaller than the elastic force of the retraction spring.

[0078] As the nonlinear mechanism for starting the operation, a stroke buffer spring arranged in parallel with the retraction spring and capable of applying elastic force to the piston of the push drive unit may be used. The elastic force of the stroke buffer spring may be smaller than the elastic force of the retraction spring.

[0079] The nonlinear mechanism for starting the action may have a structure for applying elastic force to the piston of the push drive unit via the working fluid (driving fluid) in the driving pressure generating mechanism. In this case, the nonlinear mechanism for starting the action may have a structure connected to the piston of the push drive unit, or may have a structure not connected to the piston of the push drive unit. The nonlinear mechanism for starting the action can apply elastic force to the piston from the side opposite to the retraction spring in the extension direction of the piston.

[0080] When the nonlinear mechanism is not connected to the piston of the push drive unit, the nonlinear mechanism is arranged at a position on the side of the piston opposite to the retraction spring relative to the extension direction. The nonlinear mechanism can be connected to a pipe connecting the drive pressure generating mechanism and the push drive unit.

[0081] In a gate valve of one embodiment of the present invention, the starting action nonlinear mechanism has one of an elastic mechanism, an elastic pressure adjustment mechanism and an elastic fluid, the elastic mechanism is arranged on a hydraulic circuit constructed by connecting the driving pressure generating mechanism and the pushing drive part, the elastic pressure adjustment mechanism is connected to the hydraulic circuit, and the elastic fluid is connected to the hydraulic circuit.

[0082] The nonlinear mechanism for starting operation may include an elastic mechanism, and the elastic mechanism may be disposed in a hydraulic circuit configured to connect the drive pressure generating mechanism and the push drive unit.

[0083] According to the above structure, the nonlinear mechanism for starting the action may have a structure capable of applying elastic force to the piston of the push drive portion via the working fluid (driving fluid) in the driving pressure generating mechanism. In this case, the elastic mechanism may have a structure connected to the piston of the push drive portion, or may have a structure not connected to the piston of the push drive portion. The elastic mechanism can adjust the working pressure acting on the piston from the side opposite to the retraction spring in the expansion and contraction direction of the piston.

[0084] When the elastic mechanism is not connected to the piston of the push drive unit, the elastic mechanism is arranged at a position on the side of the piston opposite to the retraction spring with respect to the telescopic direction. The elastic mechanism may be a telescopic piston arranged in a pipe connecting the driving pressure generating mechanism and the push drive unit. The telescopic piston may be a structure that can be telescoped along the axial direction of the pipe in the pipe, and can be telescoped into a linear elastic deformation according to the applied working pressure. The telescopic piston may have a structure that can freely move along the axial direction of the pipe inside the pipe.

[0085] Specifically, the telescopic piston can be constructed by two piston parts and an elastic part that are separated and arranged inside the pipeline. The elastic part is arranged between the two piston parts. Both piston parts can have a structure that can move freely along the pipeline inside the pipeline. The telescopic piston has an elastic part that can change the distance between the two piston parts inside the pipeline according to the rise and fall of the working pressure. The elastic part can be a part such as a spring connecting the two piston parts. In the case where the elastic part is set as a part such as a spring, it can be elastically deformed to the same extent as a weak spring relative to the working pressure.

[0086] The elastic part may be a compressible fluid or the like filled between the two piston parts. The compressible fluid may be, for example, air. The compressible fluid may be air below atmospheric pressure. The compressible fluid may be air at atmospheric pressure.

[0087] The telescopic piston may be configured to be capable of applying an elastic force to the piston from a side opposite to the retraction spring in the telescopic direction of the piston.

[0088] The nonlinear mechanism for starting operation may include an elastic pressure adjustment mechanism connected to a hydraulic circuit, and the hydraulic circuit may be configured to connect the drive pressure generating mechanism and the push drive unit.

[0089] The nonlinear mechanism for starting the action has the following structure: that is, the structure can make the working pressure applied to the piston of the push drive part in a state capable of nonlinear action by adjusting the working pressure of the working fluid (driving fluid) generated by the driving pressure generating mechanism. The nonlinear mechanism for starting the action can be another hydraulic circuit connected to the driving pressure generating mechanism. In the other hydraulic circuit, the working pressure applied to the piston of the push drive part is set within a prescribed range so that the telescopic movement of the push drive part can be linear at the position abutting against the valve body according to the rise and fall of the working pressure applied from the driving pressure generating mechanism to the push drive part. In addition, in the other hydraulic circuit, the working pressure applied to the piston of the push drive part is set within a prescribed range so that the telescopic movement of the push drive part can be nonlinear at the position most separated from the valve body according to the rise and fall of the working pressure applied from the driving pressure generating mechanism to the push drive part. As another hydraulic circuit, an accumulator can be used.

[0090] Through another hydraulic circuit, the push drive part can perform nonlinear motion at a position separated from the valve body and allowing the valve body to rotate. Therefore, even when the gate valve is heated and the working fluid (working oil) that causes the push drive part to perform telescopic motion undergoes thermal expansion, the push drive part can be prevented from accidentally protruding toward the valve body. Alternatively, according to another hydraulic circuit, the push drive part may not be able to perform smooth telescopic motion due to the force received from a portion (for example, a sealing material or a friction surface, etc.) that is deformed or rubbed due to the telescopic motion of the push drive part. In contrast, according to the above-mentioned structure, smooth telescopic motion of the push drive part can be achieved.

[0091] The nonlinear mechanism for starting operation may include an elastic fluid, and the elastic fluid may be disposed in a hydraulic circuit configured to connect the drive pressure generating mechanism and the push drive unit.

[0092] The elastic fluid is a fluid that can achieve nonlinear motion by applying elastic force to the piston of the push drive unit via the working fluid (driving fluid) in the driving pressure generating mechanism. The elastic fluid can adjust the working pressure applied to the piston of the push drive unit. In this case, the elastic fluid can be located in a position in contact with the piston of the push drive unit in the oil pressure circuit (pipeline) or in a position not in contact with the piston of the push drive unit. The elastic fluid can apply elastic force to the piston from the side opposite to the retraction spring in the expansion and contraction direction of the piston.

[0093] In the hydraulic circuit (pipeline), when the elastic fluid is not in contact with the piston of the push drive unit, the elastic fluid can be a bubble arranged in the pipeline connecting the drive pressure generating mechanism and the push drive unit. The volume of the elastic fluid can change in the pipeline. The volume of the elastic fluid can change linearly according to the working pressure. In addition, when the working fluid is a non-compressible fluid, it has pressure isotropy. Therefore, by only arranging the elastic fluid in the pipeline, a working pressure capable of performing nonlinear action can be obtained.

[0094] The elastic fluid can move freely along the pipe. The elastic fluid can be compressed to a level that cannot be visually recognized according to the internal pressure of the pipe. The elastic fluid can be decompressed to a level close to vacuum according to the internal pressure of the pipe. The elastic fluid can be insoluble in the working fluid inside the pipe within the assumed pressure range.

[0095] Specifically, the elastic fluid can be arranged inside the push drive unit. The elastic fluid can be arranged inside the driving pressure generating mechanism. The elastic fluid can move freely inside the working oil inside the hydraulic circuit to which the working pressure is applied. The elastic fluid can perform the same telescopic action (elastic deformation) as the above-mentioned telescopic piston. The elastic fluid can bring about the same action pressure behavior as the above-mentioned telescopic piston.

[0096] The elastic fluid may be a compressible fluid filled in the oil pressure circuit. The compressible fluid may be, for example, air. The compressible fluid may also be air below atmospheric pressure. The compressible fluid may also be air at atmospheric pressure. The compressible fluid may also be air at a pressure higher than atmospheric pressure.

[0097] In the gate valve according to one aspect of the present invention, the nonlinear start mechanism has a vacuum region, and the vacuum region is disposed in a hydraulic circuit configured to connect the drive pressure generating mechanism and the push drive unit.

[0098] The vacuum region is a structure that can realize nonlinear motion by adjusting the working pressure applied to the piston of the push drive portion via the working fluid (driving fluid) in the driving pressure generating mechanism.

[0099] In this case, when the push drive unit is retracted, after the piston of the push drive unit reaches the end of the stroke due to the decrease in the working pressure generated by the driving pressure generating mechanism, the pressure of the driving pressure generating mechanism is further reduced, thereby forming a vacuum region in the working fluid. Here, the vacuum region may be formed at a position in the hydraulic circuit (pipeline) in contact with the piston of the push drive unit, or may be formed at a position not in contact with the piston of the push drive unit.

[0100] The vacuum region can adjust the working pressure applied to the piston from the side opposite to the retraction spring in the extension direction of the piston. Here, the vacuum region can be formed by causing the piston in the main cylinder of the driving pressure generating mechanism to move further in the decompression direction from the state where the piston of the pushing driving part reaches the end of the stroke to form a negative pressure.

[0101] The stroke end refers to a limit position in the retraction direction of the piston of the push drive unit, which is pushed by the retraction spring, within the moving range of the piston of the push drive unit for extension and retraction.

[0102] When the push drive unit is extended from the state where the vacuum region is formed, the operating pressure generated by the driving pressure generating mechanism is increased. With the increase of the operating pressure, the vacuum region is first reduced and disappears.

[0103] When the working pressure rises, the piston of the push drive unit will not move from the end of the stroke before the vacuum region disappears. Further, the piston of the push drive unit will not move from the end of the stroke before the working pressure generated by the drive pressure generating mechanism rises and a force greater than the elastic force of the retraction spring is obtained.

[0104] Furthermore, when the working pressure generated by the driving pressure generating mechanism increases and a force greater than the elastic force of the retraction spring is obtained, the vacuum region in the pipe disappears, and thus the piston of the pushing driving unit performs a linear motion.

[0105] In the push drive unit that performs linear motion by the working pressure of the drive pressure generating mechanism and the retraction spring, nonlinear motion can be achieved by forming a vacuum region.

[0106] Since a vacuum region is formed at the beginning of the rise of the working pressure, the volume in the pipe is reduced before the retraction spring due to the rise of the working pressure of the driving pressure generating mechanism. After the vacuum region disappears, the retraction spring contracts due to the rise of the working pressure of the driving pressure generating mechanism, thereby performing a linear action.

[0107] The vacuum region is formed after the retraction spring is extended to the spring length. Therefore, the retraction spring is extended first by the decrease in the working pressure generated by the driving pressure generating mechanism. After the length of the retraction spring becomes maximum and the linear action is completed, the vacuum region is formed later than the decrease in the working pressure of the driving pressure generating mechanism.

[0108] By forming a vacuum area, the push drive part can perform nonlinear motion at a position separated from the valve body and enabling the valve body to rotate. Thus, even when the gate valve is heated and the temperature rises, the working pressure that causes the push drive part to perform the telescopic motion is transmitted from the driving pressure generating mechanism to the working fluid (working oil) of the push drive part, which undergoes thermal expansion, and the phenomenon of accidentally protruding the push drive part toward the valve body can be prevented. Alternatively, sometimes because a vacuum area is not formed, the push drive part cannot perform smooth telescopic motion due to the force received from the part (for example, a sealing material or a friction surface, etc.) that is deformed or rubbed due to the telescopic motion of the push drive part. In contrast, by forming a vacuum area, smooth telescopic motion of the push drive part can be achieved.

[0109] In addition, the reduction of the working pressure to form the vacuum region may be achieved by a driving pressure generating mechanism, or may be achieved by a pressure control mechanism connected to a pipe or the like, independently of the driving pressure generating mechanism that causes the push drive unit to perform linear motion.

[0110] In the gate valve of one aspect of the present invention, a plurality of push drive parts are provided along the circumferential direction of the valve body (movable valve frame part), and the nonlinear motion imparting mechanism causes the plurality of push drive parts to operate so that the linear motions of the plurality of push drive parts coincide with each other.

[0111] According to the above structure, in the plurality of pushing drive parts, nonlinear motion can be performed simultaneously by the nonlinear motion imparting mechanism. All the pushing drive parts can perform nonlinear motion at a position separated from the valve body and enabling the valve body to rotate. Thus, even when the gate valve is heated and the temperature rises, the working pressure that causes the pushing drive parts to perform telescopic motion is transmitted from the driving pressure generating mechanism to the working fluid (working oil) of the pushing drive parts, which undergoes thermal expansion, and the phenomenon that all the pushing drive parts accidentally protrude toward the valve body can be prevented. Alternatively, according to the nonlinear motion imparting mechanism, sometimes all the pushing drive parts cannot perform smooth telescopic motion due to the force received from the parts (for example, sealing materials or friction surfaces, etc.) that are deformed or rubbed due to the telescopic motion of the pushing drive parts. In contrast, according to the above structure, smooth telescopic motion of the pushing drive parts can be achieved.

[0112] Here, consider the case where the nonlinear action imparting mechanism is not provided on the gate valve. At this time, it is considered that there are reasons that hinder the telescopic action in the multiple push-drive parts (such as different adhesion states or obstructive friction forces, etc.) and the levels of the reasons are different from each other. Therefore, when the working pressure is increased by the driving pressure generating mechanism, according to the difference in the level, only the push-drive part that is easiest to move starts to move. Then, the working fluid will not flow into the other push-drive parts that are not moving. Therefore, through the increase in working pressure, only the push-drive part that moves first will move further. If this state continues, the total amount of working fluid moved by the driving pressure generating mechanism in order to extend the multiple push-drive parts will only move the push-drive part that moves first. Therefore, only the push-drive part that moves first will move further.

[0113] That is, due to the difference in the level of the cause of the obstruction of the extending action, only one of the pushing drive portions will protrude.

[0114] Similarly, when the working pressure drops, although the working fluid will flow out from the moving pushing drive part, only one pushing drive part will not move and the protruding state will not change.

[0115] In contrast, by providing a nonlinear motion imparting mechanism, nonlinear motion can be realized in all the pushing drive parts. Therefore, the influence caused by the reasons that hinder the telescopic motion in all the pushing drive parts can be eliminated. By providing a nonlinear motion imparting mechanism, the phenomenon that all the pushing drive parts cannot perform smooth telescopic motion can be prevented. By providing a nonlinear motion imparting mechanism, all the pushing drive parts can perform smooth telescopic motion at the same time.

[0116] Therefore, by providing the nonlinear action imparting mechanism on the valve body, the protrusion amounts of the plurality of push drive parts can be made uniform, thereby preventing the phenomenon that only one push drive part protrudes greatly. By providing the nonlinear action imparting mechanism, the influence of the volume expansion of the working fluid caused by the temperature rise of the gate valve can be suppressed.

[0117] According to the present invention, regardless of the presence of thermal expansion of the working fluid (working oil) or factors that hinder the expansion and contraction of the pushing drive portion, it is possible to provide a gate valve in which the pushing drive portion does not affect the rotation of the valve body. BRIEF DESCRIPTION OF THE DRAWINGS

[0118] Figure 1 It is a schematic cross-sectional view showing a gate valve according to a first embodiment of the present invention.

[0119] Figure 2 It is a perspective view showing a gate valve according to a first embodiment of the present invention.

[0120] Figure 3It is a schematic cross-sectional view showing a push drive portion, a drive pressure generating mechanism, and a nonlinear motion imparting mechanism in a gate valve according to a first embodiment of the present invention.

[0121] Figure 4 It is a PX chart showing the operation of the pressing drive unit in the gate valve according to the first embodiment of the present invention.

[0122] Figure 5 This is a schematic cross-sectional view showing a push drive portion in a gate valve.

[0123] Figure 6 It is a PX chart showing the operation of the push drive unit in the gate valve.

[0124] Figure 7 This is an XV graph showing the operation of the push drive unit in the gate valve.

[0125] Figure 8 It is a PX graph showing another example of the operation of the pressing drive unit in the gate valve according to the first embodiment of the present invention.

[0126] Fig. 9 It is a schematic cross-sectional view showing a push drive portion, a drive pressure generating mechanism, and a nonlinear motion imparting mechanism in a gate valve according to a second embodiment of the present invention.

[0127] Fig.10 It is a schematic cross-sectional view showing a push drive portion, a drive pressure generating mechanism, and a nonlinear motion imparting mechanism in a gate valve according to a third embodiment of the present invention.

[0128] Fig.11 It is a schematic cross-sectional view showing a push drive portion, a drive pressure generating mechanism, and a nonlinear motion imparting mechanism in a gate valve according to a fourth embodiment of the present invention.

[0129] Fig.12 It is a schematic cross-sectional view showing a pressing drive portion, a driving pressure generating mechanism, and a nonlinear motion imparting mechanism in a gate valve according to a fifth embodiment of the present invention.

[0130] Fig.13 It is a diagram showing the operation of the pressing drive unit in the gate valve according to the fifth embodiment of the present invention.

[0131] Fig.14 It is a schematic diagram showing another example of the pressing drive unit in the embodiment of the gate valve of the present invention. DETAILED DESCRIPTION

[0132] <First Embodiment>

[0133] Next, a gate valve according to a first embodiment of the present invention will be described with reference to the drawings.

[0134] In addition, in the drawings used in the following description, in order to make each structural element a size that can be recognized in the drawings, the size and ratio of each structural element are appropriately set to be different from the actual structural element. The technical scope of the present invention is not limited to the embodiments described below, and various changes can be made within the scope of the present invention.

[0135] Figure 1 It is a schematic cross-sectional view showing the gate valve according to the present embodiment. Figure 2 2 is a perspective view showing a gate valve according to this embodiment. Figure 1 and Figure 2 In the figure, reference numeral 100 is a gate valve.

[0136] The gate valve 100 of this embodiment is a pendulum type sliding valve. Figure 1 As shown, the gate valve 100 of this embodiment includes a valve housing 10, a hollow portion 11, a valve body 5, a rotating shaft 20, a rotating drive portion 21, a pressing drive portion 70, a hydraulic drive device 700, and a nonlinear motion imparting mechanism 770. The hydraulic drive device 700 is an example of an incompressible fluid drive portion.

[0137] The valve box 10 has a hollow portion 11, a first opening portion 12a, and a second opening portion 12b. The first opening portion 12a and the second opening portion 12b form a flow channel H that is arranged opposite to each other and connected with the hollow portion 11. The hollow portion 11 is located between the first opening portion 12a and the second opening portion 12b. The valve box 10 has an inner surface 10b. In the inner surface 10b, the portion located around the first opening portion 12a is a peripheral portion. The flow channel H is set to extend from the second opening portion 12b toward the first opening portion 12a.

[0138] The valve body 5 is disposed in the hollow portion 11 of the valve box 10. The valve body 5 can open and close the flow path H.

[0139] The rotating shaft 20 has an axis line. The axis line of the rotating shaft 20 extends in the direction of the flow path H. The rotating shaft 20 supports the valve body 5 so as to be rotatable about the axis line relative to the valve housing 10 .

[0140] The rotary shaft 20 supports the valve body 5 so as to be rotatable between a retracted position (valve opening position) and a valve opening shielding position (sliding preparation position) in the hollow portion 11. When viewed from the direction of the flow channel H, the valve body 5 does not overlap with the first opening 12a and the second opening 12b in the retracted position. When viewed from the direction of the flow channel H, the valve body 5 overlaps with the first opening 12a and the second opening 12b in the valve opening shielding position.

[0141] In the retracted position, the valve body 5 is in an open state in which it is retracted from the first opening 12 a and the flow path H can communicate.

[0142] In the valve opening shielding position, the valve body 5 is in a closable state to shield the first opening 12 a .

[0143] In the gate valve 100, the valve body 5 is operated in two steps. Specifically, in the first step of the operation of the valve body 5, the valve body 5 is rotated and moved between the retreat position and the valve opening shielding position. That is, the valve body 5 moves from the retreat position to the valve opening shielding position, and moves from the valve opening shielding position to the retreat position. In the second step of the operation of the valve body 5, the valve body 5 moves (linearly moves) in the thickness direction of the valve body 5 between the valve opening shielding position and the valve closing position. That is, the valve body 5 moves from the valve opening shielding position to the valve closing position, and moves from the valve closing position to the valve opening shielding position.

[0144] In the first step of the operation of the valve body 5, the valve body 5 rotates around the rotation shaft 20. The rotation shaft 20 functions as a position switching unit of the valve body 5.

[0145] The rotation drive unit 21 drives the rotation shaft 20 to rotate. The rotation of the rotation shaft 20 allows the valve body 5 to reciprocate between the retreat position and the valve opening shielding position.

[0146] The valve body 5 is configured by the neutral valve portion 30, the valve frame portion 63, and the movable valve portion 54. The movable valve portion 54 is an example of a movable valve frame portion.

[0147] The neutral valve portion 30 is connected to the rotating shaft 20. The neutral valve portion 30 is fixed to the rotating shaft 20. The neutral valve portion 30 is in the direction along the flow path H (or in the Figure 1 The neutral valve portion 30 is located at the center of the hollow portion 11 in the top view in the schematic cross-sectional view shown in FIG. 1 . The neutral valve portion 30 rotates around the axis integrally with the rotating shaft 20. The neutral valve portion 30 maintains the center position of the hollow portion 11 in the direction along the flow path H at all positions of the retracted position, the valve opening shielding position, and the valve closing position.

[0148] The valve frame 63 is connected to the neutral valve portion 30 . The valve frame 63 is located around the movable valve portion 54 . The valve frame 63 is located at the center of the hollow portion 11 in the direction along the flow path H. The valve frame 63 is fixed to the neutral valve portion 30 .

[0149] The valve frame 63 is located near the center of the hollow portion 11 along the flow path H. The valve frame 63 maintains a position near the center of the hollow portion 11 in all positions including the retracted position, the valve opening shielding position, and the valve closing position.

[0150] The movable valve portion 54 is connected to the valve frame portion 63. The movable valve portion 54 can change its position in the direction of the flow path H relative to the neutral valve portion 30 and the valve frame portion 63 at the valve opening shielding position and the valve closing position.

[0151] In the retracted position, the position of the movable valve portion 54 is maintained at the center of the flow path H direction like the hollow portion 11. In the valve opening shielding position, the position of the movable valve portion 54 is maintained at the center of the flow path H direction like the hollow portion 11. Between the retracted position and the valve opening shielding position, the position of the movable valve portion 54 is maintained at the center of the flow path H direction like the hollow portion 11.

[0152] The movable valve portion 54 is slidable relative to the valve frame portion 63 in the direction of the flow path H. The movable valve portion 54 is slidable relative to the valve frame portion 63 in the direction of the flow path H between the valve opening shielding position and the valve closing position.

[0153] In the valve closed position, the movable valve portion 54 can be in close contact with the inner surface 10b of the valve box 10 located around the first opening 12a. A valve plate sealing gasket may be provided on either the movable valve portion 54 or the inner surface 10b of the valve box 10. The valve plate sealing gasket can seal the inner surface 10b of the valve box 10 located around the first opening 12a and the movable valve portion 54.

[0154] The pushing drive unit 70 is buried in the valve box 10. The pushing drive unit 70 is an example of a pushing cylinder. The gate valve 100 includes a plurality of pushing drive units 70. The plurality of pushing drive units 70 are arranged along the circumferential direction of the movable valve unit 54. The pushing drive unit 70 is configured to push the movable valve unit 54 located at the valve opening shielding position toward the sealing surface. The pushing drive unit 70 includes a telescopic cylinder capable of pushing the movable valve unit 54 to the valve closing position. The pushing drive unit 70 is a force applying unit that applies force to the movable valve unit 54 when extended.

[0155] The push drive unit 70 can retract the movable valve unit 54 in a direction that weakens the push force on the movable valve unit 54 in the valve closing position. The push drive unit 70 can retract the movable valve unit 54 until the movable valve unit 54 moves from the valve closing position to the valve opening shielding position. The push drive unit 70 can retract the movable valve unit 54 in a direction away from the movable valve unit 54 in the valve opening shielding position. The push drive unit 70 can retract the movable valve unit 54 until the movable valve unit 54 further leaves the position of the movable valve unit 54 in the valve opening shielding position. The push drive unit 70 can retract the movable valve unit 54 until the inner surface 10b of the valve box 10 and the surface of the movable valve unit 54 facing the first opening 12a are on the same surface. The push drive unit 70 can retract the movable valve unit 54 until the movable valve unit 54 leaves so that the valve body 5 can rotate between the retreat position and the valve opening shielding position.

[0156] At the valve opening shielding position, a position between the valve opening shielding position and the valve closing position, and the valve closing position, the pushing drive unit 70 can apply force to the movable valve portion 54 toward the first opening portion 12a in the direction of the flow channel H. At the valve closing position, the pushing drive unit 70 pushes the movable valve portion 54 so that the valve sheet sealing gasket can be tightly engaged with the inner surface 10b of the valve box 10 and the movable valve portion 54. The pushing drive unit 70 pushes the surroundings of the movable valve portion 54 in the valve opening shielding position toward the flow channel H to move it. The flow channel H is closed by the movable valve portion 54 that has moved.

[0157] The plurality of pushing drive parts 70 can be extended and retracted along the flow channel H. The extension axes of the plurality of pushing drive parts 70 are parallel to each other. The extension ranges of the plurality of pushing drive parts 70 in the direction along the flow channel H are all within the same range. The plurality of pushing drive parts 70 can push the movable valve part 54 at the same time. The plurality of pushing drive parts 70 can leave the movable valve part 54 at the same time. The plurality of pushing drive parts 70 can perform the same extension and retraction action together.

[0158] The plurality of push drive units 70 are all connected to a hydraulic drive device 700. The push drive unit 70 can be driven to extend and retract according to the working pressure applied by the working fluid. The hydraulic drive device 700 can apply the working pressure to the push drive unit 70.

[0159] The hydraulic drive device 700 is connected to the push drive unit 70. The hydraulic drive device 700 supplies and discharges a non-compressible fluid (working oil) to the push drive unit 70. The hydraulic drive device 700 can supply and discharge working oil to the push drive unit 70 to apply working pressure. The hydraulic drive device 700 has a driving pressure generating mechanism 701 described later. Typically, the driving pressure generating mechanism 701 is a volume transfer type structure. The hydraulic drive device 700 can apply working pressure to a plurality of push drive units 70 at the same time. The hydraulic drive device 700 can drive a plurality of push drive units 70 at the same time.

[0160] The gate valve 100 according to the embodiment of the present invention rotates the rotating shaft 20 in a direction intersecting the flow path H direction by the rotation drive unit 21. As the rotating shaft 20 rotates, the neutral valve portion 30 fixed to the rotating shaft 20 also rotates. At the same time, the movable valve portion 54 connected to the neutral valve portion 30 also rotates integrally with the neutral valve portion 30. During this rotation, the movable valve portion 54 does not slide in the thickness direction which is the flow path H direction.

[0161] The movable valve portion 54 moves between the retreat position and the valve opening shielding position in a pendulum motion by the rotation of the valve body 5. In other words, the retreat position is a position in the hollow portion 11 where the flow channel H is not provided. The valve opening shielding position is a position corresponding to the first opening 12a, where the flow channel H is shielded.

[0162] When the valve body 5 is at the valve opening shielding position, the hydraulic drive device 700 can operate. When the valve body 5 is not at the valve opening shielding position (including at the retreat position), the hydraulic drive device 700 does not operate.

[0163] The gate valve 100 according to the embodiment of the present invention can extend and retract the plurality of push drive parts 70 driven by the hydraulic drive device 700 toward the movable valve part 54 at the valve opening shielding position.

[0164] In the gate valve 100 , when the pressing drive portion 70 is not extending, the movable valve portion 54 is maintained at the center position of the hollow portion 11 inside the valve housing 10 .

[0165] When the plurality of pressing drive portions 70 abut against the movable valve portion 54 at the valve opening shielding position and the valve closing position, the position of the movable valve portion 54 in the flow path H direction can be changed relative to the valve frame portion 63 .

[0166] Furthermore, a biasing portion (neutral biasing portion) may be provided between the valve frame portion 63 and the movable valve portion 54 . The biasing portion biases the movable valve portion 54 toward the center of the hollow portion 11 in the flow path H direction relative to the valve frame portion 63 .

[0167] The thickness dimensions of the valve frame portion 63 and the movable valve portion 54 in the flow path H direction can be adjusted by pressing the driving portion 70 and the biasing portion (neutral biasing portion) of the valve frame portion 63 .

[0168] Figure 3 It is a schematic cross-sectional view showing a push drive portion, a drive pressure generating mechanism, and a nonlinear motion imparting mechanism in the gate valve according to the present embodiment.

[0169] The plurality of push drive units 70 are all built into the valve box 10. Figure 3 In the figure, three pressing drive parts 70 are shown for convenience of explanation, but the number of the pressing drive parts 70 is not limited to three. The plurality of pressing drive parts 70 each constitutes a hydraulic drive device 700 .

[0170] The hydraulic drive device 700 includes a plurality of pressing drive units 70, a drive pressure generating mechanism 701, a pipe 702, and a nonlinear motion imparting mechanism 770. The pipe 702 is an example of a hydraulic circuit.

[0171] The hydraulic drive device 700 is filled with a working fluid. The working fluid is a non-compressible fluid such as hydraulic oil. The plurality of pressing drive parts 70 are filled with a working fluid.

[0172] The plurality of push drive units 70 are all connected to a drive pressure generating mechanism 701 via a pipe 702. The drive pressure generating mechanism 701 is a master cylinder of the hydraulic drive device 700.

[0173] The driving pressure generating mechanism 701 generates working pressure. The working pressure generated in the driving pressure generating mechanism 701 is applied to the plurality of pushing drive parts 70 via the pipe 702. If the driving pressure generating mechanism 701 generates working pressure, working oil is supplied to the plurality of pushing drive parts 70. The plurality of pushing drive parts 70 have the same structure.

[0174] Next, one pressing drive unit 70 will be described.

[0175] The push drive unit 70 includes a fixed unit 71, a movable unit 72, a retraction spring 73 as a biasing member, a buffer unit 75, and a sealing unit 76. The fixed unit 71 is, for example, a cylinder. The movable unit 72 is, for example, a piston. The retraction spring 73 is an example of a push spring.

[0176] The fixed portion 71 is fixed to the valve housing 10. The fixed portion 71 is built in the valve housing 10. The fixed portion 71 accommodates the movable portion 72. The fixed portion 71 can drive the movable portion 72 to extend and retract by the operating pressure (oil pressure) supplied from the driving pressure generating mechanism 701.

[0177] The movable portion 72 can be extended and retracted from the fixed portion 71 in the direction along the flow channel H. The movable portion 72 is accommodated in the fixed portion 71. The movable portion 72 can be extended and retracted from the fixed portion 71 in the direction toward the movable valve portion 54 by working pressure. The movable portion 72 has a contact portion 72a. The contact portion 72a can contact with the movable valve portion 54. The contact portion 72a is the front end portion of the movable portion 72. The contact portion 72a can perform a telescopic action integrally with the movable portion 72. The contact portion 72a can protrude from the fixed portion 71 in the direction along the flow channel H. The contact portion 72a can protrude from the fixed portion 71 toward the movable valve portion 54 in the valve opening shielding position and the valve closing position.

[0178] The retraction spring 73 is a biasing member capable of biasing the movable portion 72 in a direction in which the movable portion 72 retracts. The retraction spring 73 can bias the movable portion 72 in a direction away from the movable valve portion 54. The retraction spring 73 can be constructed by a cylindrical spring. The retraction spring 73 is accommodated in the fixed portion 71 as a cylinder. The retraction spring 73 biases the movable portion 72 in a direction in which the abutting portion 72a retracts.

[0179] The buffer portion 75 is a buffer space. When the hydraulic oil pressure leaks from the pressing drive portion 70, the buffer portion 75 is a space for accommodating the hydraulic oil pressure before the hydraulic oil pressure leaks to the outside (vacuum chamber) which is the vacuum side.

[0180] When the movable portion 72 performs an expansion and contraction operation, the seal portion 76 also performs a seal to prevent the hydraulic oil from leaking to the outside (vacuum chamber) which is the vacuum side.

[0181] The pipeline 702 connects the plurality of push drive units 70 and the drive pressure generating mechanism 701. The pipeline 702 is filled with a working fluid (working oil). The pipeline 702 supplies and discharges the working oil between the drive pressure generating mechanism 701 and the push drive unit 70. The pipeline 702 supplies the working pressure from the drive pressure generating mechanism 701 to the push drive unit 70.

[0182] The push drive unit 70 extends the contact portion 72a by the working pressure applied by the drive pressure generating mechanism 701. The contact portion 72a of the extended movable portion 72 abuts against the movable valve portion 54 at the valve opening shielding position, thereby moving the movable valve portion 54 toward the first opening 12a. The movable portion 72 can be extended to the extent that the movable valve portion 54 abuts against the inner surface 10b. The movable portion 72 can be extended to the extent that the movable valve portion 54 can be pressed against the inner surface 10b and sealed. The movable portion 72 can be extended to the extent that the movable valve portion 54 can be pressed to the valve closing position.

[0183] When the working pressure from the driving pressure generating mechanism 701 is reduced, the pushing driving part 70 causes the movable part 72 to retract by the elastic force of the retraction spring 73. When the working pressure from the driving pressure generating mechanism 701 is increased, the pushing driving part 70 causes the movable part 72 to extend against the elastic force of the retraction spring 73. The contact part 72a of the retracted movable part 72 leaves the movable valve part 54 and is built and stored in the valve box 10.

[0184] Consider the valve closing action of the gate valve 100 .

[0185] The retracted storage state of the abutment portion 72a of the pushing drive portion 70 is set as an initial state. From this initial state, working oil is supplied to the pushing drive portion 70 from the driving pressure generating mechanism 701 via the pipeline 702. The working pressure of the pushing drive portion 70 rises. With the increase in the working pressure, the working pressure becomes greater than the force (elastic force) of the retraction spring 73, and the movable portion 72 is extended. Then, the extended abutment portion 72a of the pushing drive portion 70 contacts the movable valve portion 54. Further, the pushing drive portion 70 pushes the movable valve portion 54 through the extended abutment portion 72a. When the abutment portion 72a pushes the movable valve portion 54, the movable valve portion 54 moves toward the first opening portion 12a. The further moved movable valve portion 54 contacts the inner surface 10b of the valve box 10. Furthermore, the pressing drive unit 70 presses the movable valve portion 54 against the inner surface 10 b of the valve box 10 to set the movable valve portion 54 to a closed state, thereby closing the flow path H (valve closing operation).

[0186] Consider the valve opening operation of the gate valve 100 .

[0187] The valve closed state in which the movable part 72 is extended causes the working pressure supplied from the driving pressure generating mechanism 701 via the pipe 702 to decrease. Due to the decrease in working pressure, the working oil moves from the push drive part 70 to the driving pressure generating mechanism 701. Due to the decrease in working pressure, the push drive part 70 uses the force (elastic force) of the retraction spring 73 to retract the movable part 72. At the same time, when the abutment part 72a retracts, the force applying part (neutral force applying part) causes the movable valve part 54 to leave the first opening part 12a. As a result, the movable valve part 54 leaves the inner surface 10b of the valve box 10. When the movable part 72 further retracts, the abutment part 72a retracts. At the same time, the movable valve part 54 retracts to the central position of the hollow part 11 in the direction of the flow channel H. By placing the movable valve part 54 in the central position of the hollow part 11 in the direction of the flow channel H, the flow channel H is opened (release action).

[0188] When the movable portion 72 further retracts, the contact portion 72a is separated from the movable valve portion 54. The contact portion 72a is housed in the fixed portion 71. The process until the contact portion 72a is housed is included in the releasing operation.

[0189] In this way, by using the pushing drive part 70 to make the movable valve part 54 abut against the inner surface 10b of the valve box 10 for mechanical contact action and using the force applying part (neutral force applying part) to pull the movable valve part 54 away from the inner surface of the valve box 10 for mechanical separation action, the valve body 5 can be closed and released.

[0190] After the release operation, when the rotary shaft 20 is rotated by the rotation drive unit 21 (retraction operation), the neutral valve portion 30 and the movable valve portion 54 also rotate in the same direction in accordance with the rotation.

[0191] The gate valve 100 performs a valve opening operation in which the movable valve portion 54 is retracted from the valve opening shielding position to the retracted position to be in a valve open state through the release operation and the retracting operation.

[0192] The push drive unit 70 is driven by the working pressure of the working fluid (pressurized incompressible fluid) supplied from the driving pressure generating mechanism 701 through the pipe 702. The push drive unit 70 can perform linear motion by the working pressure supplied by the driving pressure generating mechanism 701 and the force of the retraction spring 73. Near the abutment portion 72a and the movable valve portion 54, the push drive unit 70 performs linear motion.

[0193] For the push drive part 70, when the working pressure supplied by the driving pressure generating mechanism 701 exceeds the acting force of the retraction spring 73, the force generated by the working pressure is greater than the acting force of the retraction spring 73. As a result, the movable part 72 is extended, and the movable part 72 moves to a position where the working pressure and the acting force are opposed. For the push drive part 70, when the working pressure supplied by the driving pressure generating mechanism 701 is less than the acting force of the retraction spring 73, the movable part 72 is retracted by the acting force of the retraction spring 73. As a result, the movable part 72 moves to a position where the working pressure and the acting force are opposed.

[0194] The movable portion 72 can perform linear expansion and contraction motion relative to the combined force of the working pressure supplied by the driving pressure generating mechanism 701 and the urging force of the retraction spring 73 .

[0195] The nonlinear motion imparting mechanism 770 can realize linear motion and nonlinear motion for the extension and retraction motion of the push drive unit 70 driven by the drive pressure generating mechanism 701. In the linear motion of the nonlinear motion imparting mechanism 770, the push drive unit 70 performs linear motion at a position near the valve closing position abutted by the movable valve unit 54. In the nonlinear motion of the nonlinear motion imparting mechanism 770, the push drive unit 70 performs nonlinear motion at a position where the abutting portion 72a of the push drive unit 70 is separated from the movable valve unit 54.

[0196] Here, if the position of the movable valve portion 54 that changes continuously during the reciprocating movement between the valve closing position and the valve opening shielding position is considered, the sentence "the position near the valve closing position abutted by the movable valve portion 54" includes a first position and a second position. The first position is the position before the movable valve portion 54 abuts the valve closing position. The second position is the position after the movable valve portion 54 abuts the valve closing position. Since the movable valve portion 54 abuts the valve closing position at the second position, a linear action is sometimes obtained by combining the reaction force generated between the valve box 10 and the movable valve portion 54 and the driving force of the push drive portion 70.

[0197] In particular, the nonlinear motion imparting mechanism 770 can cause the pressing drive unit 70 to perform nonlinear motion. The nonlinear motion imparting mechanism 770 causes the pressing drive unit 70 to perform nonlinear motion when the contact portion 72a is at a position away from the movable valve portion 54.

[0198] Regarding the operation of the plurality of pushing drive units 70, for example, one of the plurality of pushing drive units 70 performs nonlinear operation, while the other pushing drive units 70 mainly perform linear operation. In this case, the plurality of pushing drive units 70 perform linear operation as a whole.

[0199] The nonlinear motion imparting mechanism 770 in this embodiment is a stroke buffer spring 74 connected in parallel with the retraction spring 73. The stroke buffer spring 74 and the retraction spring 73 independently urge the movable portion 72. The stroke buffer spring 74 is an example of a nonlinear mechanism for starting motion.

[0200] Regarding the stroke buffer spring 74 and the retraction spring 73, the apparent spring constant in the linear region Lnr described later is greater than the apparent spring constant in the region Sbr described later. There is no restriction on the single spring constants of the stroke buffer spring 74 and the retraction spring 73. In addition, when the stroke buffer spring 74 has a spring constant K2, when the spring constant of the retraction spring 73 is set to K0, the spring constant K2 can be set in a manner that satisfies K0≥K2. That is, the spring constant of the stroke buffer spring 74 can be smaller than the spring constant of the retraction spring 73. The elastic force of the stroke buffer spring 74 can be smaller than the elastic force of the retraction spring 73. When the retraction spring 73 is set to a strong spring, the stroke buffer spring 74 is a weak spring.

[0201] The stroke buffer spring 74 is coaxially arranged with the retraction spring 73. The stroke buffer spring 74 applies elastic force to the movable portion 72 as a piston from the same side as the retraction spring 73. The stroke buffer spring 74 is arranged on the same side as the retraction spring 73 with respect to the movable portion 72 as a piston in the expansion and contraction direction of the movable portion 72.

[0202] The stroke buffer spring 74 may be formed of a wire material different from that of the retraction spring 73. The coil diameter of the stroke buffer spring 74 is different from that of the retraction spring 73. The coil diameter of the stroke buffer spring 74 is smaller than that of the retraction spring 73. The stroke buffer spring 74 may also be formed so that its wire diameter is smaller than that of the retraction spring 73. The coil length of the stroke buffer spring 74 in the free length state may be different from that of the retraction spring 73. The coil length of the stroke buffer spring 74 is preferably longer than that of the retraction spring 73. The stroke buffer spring 74 is not connected to the retraction spring 73. The stroke buffer spring 74 and the retraction spring 73 are a double spring structure when viewed from the push drive portion 70.

[0203] At the position where the movable part 72 retracts the most, the end of the retraction spring 73 near the movable part 72 is locked on the fixed part 71 by the slidable locking part 73r and is separated from the movable part 72. When the locking part 73r contacts the movable part 72, the locking part 73r can slide and move together with the movable part 72. In addition, when the locking part 73r leaves the movable part 72, the locking part 73r locks the end of the retraction spring 73 near the movable part 72 at the position where the retraction spring 73 no longer extends. At the typical locking position, i.e., the position where the retraction spring 73 no longer extends, the length of the retraction spring 73 is set to be less than the free length of the retraction spring 73. By setting the length of the retraction spring 73 in this way, at the position where the movable part 72 contacts the locking part 73r, the working pressure P corresponding to the increased pressure generated by setting the retraction spring 73 to be less than the free length can be given to the movable part 72.

[0204] In the extension stroke of the movable part 72 in the push drive part 70 described later, at the position where the contact part 72a retracts the most, the retraction spring 73 does not contact the movable part 72. In the extension stroke of the movable part 72 in the push drive part 70, at the position where the contact part 72a retracts the most, the stroke buffer spring 74 contacts the movable part 72.

[0205] Next, the operation of the push drive unit 70 by the nonlinear motion imparting mechanism 770 will be described.

[0206] Figure 4 : is a PX chart showing the operation of the push drive unit in the gate valve of this embodiment. Figure 4 In FIG. 1 , the horizontal axis X is the stroke (extension length) of the movable portion 72 of the push drive portion 70. The dimension of the stroke X is the length. The vertical axis P is the operating pressure applied to the push drive portion 70. The dimension of the operating pressure P is the pressure.

[0207] Regarding the push drive unit 70, Figure 4 As shown, at the stroke end of stroke X=X0, the operating pressure P is the end pressure Ps1. In addition, the stroke end is the position where the movable part 72 retracts the most in the extension direction. Typically, the stroke end is defined as the position where the push drive part 70 retracts the most in design.

[0208] When the working pressure P rises from the terminal pressure Ps1, the movable portion 72 of the push drive portion 70 extends, thereby increasing the stroke X. When the working pressure P becomes the abutment pressure Pt, the stroke X of the movable portion 72 of the push drive portion 70 becomes the abutment position Xt. At the abutment position Xt, the abutment portion 72a abuts against the movable valve portion 54. Further, when the working pressure P rises from the abutment pressure Pt, the stroke X of the movable portion 72 of the push drive portion 70 moves to a range Xp exceeding the abutment position Xt, and the abutment portion 72a pushes the movable valve portion 54.

[0209] Within the range Xp, the movable portion 72 can move to a position where the movable valve portion 54 abuts against the inner surface 10b. Figure 4 In the above, the movement within the range Xp where the stroke X is greater than the contact position Xt is omitted. Figure 4 The operation within the range where the working pressure P is greater than the contact pressure Pt is omitted.

[0210] When the operating pressure P drops from the contact pressure Pt, the movable portion 72 of the push drive portion 70 retracts according to the drop from Pt, and the stroke X decreases from the contact position Xt. When the operating pressure P drops from the contact pressure Pt, the contact portion 72 a moves away from the movable valve portion 54 .

[0211] Here, if Figure 4 As shown, when the stroke X is in the range of being near the abutment position Xt and less than the abutment position Xt, the push drive unit 70 performs linear motion. When the working pressure P is in the range of being near the abutment pressure Pt and less than the abutment pressure Pt, the push drive unit 70 performs linear motion. This range in which the stroke X and the working pressure P are in a linear relationship is the linear motion region Lnr.

[0212] In the linear action region Lnr, the stroke X of the push drive unit 70 and the working pressure P maintain a linear relationship. In the linear action region Lnr, the stroke X and the working pressure P satisfy the relationship represented by a straight line with a predetermined slope rising to the right on the graph. In addition, since the area of ​​the movable portion 72 of the piston to which the working force F is applied does not change, the working pressure P is used instead of the working force F to express it.

[0213] In the linear action region Lnr, as Figure 4 As shown in FIG. 1 , the lower limit of the stroke X of the push drive unit 70 for linear motion is Xc. In the linear motion region Lnr, the upper limit of the stroke X of the push drive unit 70 for linear motion is Xt. In the linear motion region Lnr, as shown in FIG. Figure 4 As shown, the lower limit of the operating pressure P of the push drive unit 70 for linear motion is Pn2. In the linear motion region Lnr, the upper limit of the operating pressure P of the push drive unit 70 for linear motion is Pt.

[0214] The linear action region Lnr is a range where the stroke X is between a lower limit Xc and an upper limit Xt. The linear action region Lnr is a range where the operating pressure is between a lower limit Pc and an upper limit Pt.

[0215] In the linear action region Lnr, the movable portion 72 is acted upon by the force of the stroke buffer spring 74 and the retraction spring 73. In the range where the stroke X is greater than Xc, the movable portion 72 is acted upon by the force of the stroke buffer spring 74 and the retraction spring 73. In the linear action region Lnr, the stroke buffer spring 74 and the retraction spring 73 are elastically deformed in an extended (or compressed) manner by a decrease (or increase) in the operating pressure P.

[0216] When the operating pressure P decreases, it reaches the lower limit Pn2 of the linear action region Lnr. At this time, the movable part 72 retracts and the stroke X reaches Xc. In the initial state where the stroke X reaches Xc as the operating pressure P decreases, the movable part 72 contacts the stopper 73r. Even if the stroke X=Xc is reached and the operating pressure P decreases from Pn2, the movable part 72 does not move but maintains the contact state. That is, although the operating pressure P decreases from Pn2 after reaching the stroke X=Xc, the stroke X is maintained at Xc.

[0217] Furthermore, when the operating pressure P is reduced to Pn1, the movable part 72 is in a state where only the force of the stroke buffer spring 74 is applied. When the operating pressure P is in the range of Pn2 to Pn1, the push drive part 70 performs nonlinear action. The range of the operating pressure P from Pn2 to Pn1 is the nonlinear action region NL.

[0218] like Figure 4 As shown, the nonlinear action region NL is the range from the lower limit Pn1 to the upper limit Pn2 of the working pressure P. In the nonlinear action region NL, the stroke X is maintained at Xc. Figure 4 As shown, the nonlinear action region NL is represented by a straight line between the stroke X and the working pressure P in the vertical direction of the longitudinal axis P. The nonlinear action region NL is represented by a straight line between the upper limit point NL2 (Xc, Pn2) and the lower limit point NL1 (Xc, Pn1).

[0219] In the nonlinear action region NL, the movable part 72 is acted upon by the force of the stroke buffer spring 74 and the retraction spring 73. In the nonlinear action region NL, even if the working pressure P decreases, the force of the stroke buffer spring 74 and the retraction spring 73 also changes, but the two springs do not appear to be elastically deformed. The range from the lower limit Pn1 to the upper limit Pn2 is the same as the pressurization amount of the retraction spring 73, and the position of the movable part 72 is maintained at Xc until the transfer of this amount is completed. Between the upper limit point NL2 (Xc, Pn2) and the lower limit point (Xc, Pn1), the push drive part 70 performs nonlinear action.

[0220] When the operating pressure P further decreases from the lower limit Pn1 of the nonlinear action region NL, the movable portion 72 retracts and the movable portion 72 leaves the locking portion 73r. As the operating pressure P decreases, the stroke X decreases from Xc. In the range where the stroke X is less than Xc, the retraction spring 73 does not contact the movable portion 72. In the range where the stroke X is less than Xc, only the stroke buffer spring 74 is elastically deformed.

[0221] Furthermore, when the working pressure P is reduced to Ps1, the movable part 72 reaches the stroke X=X0 which is the end of the stroke. In the stroke X=X0, the contact part 72a can be accommodated in the fixed part 71. When the working pressure P after the decrease reaches Ps1, the movable part 72 no longer retracts. The typical working pressure Ps1 value is the value brought to the movable part 72 by the elastic deformation of each stroke buffer spring 74 in the stroke X0. The working pressure P in the range of Pn1 to Ps1 is the region Sbr.

[0222] In the region Sbr, the retraction spring 73 is not in contact with the movable portion 72. In the region Sbr, only the stroke buffer spring 74 is elastically deformed. In the region Sbr, the stroke X and the operating pressure P satisfy the relationship represented by a straight line with a predetermined slope rising to the right on the graph. In the region Sbr, the stroke X and the operating pressure P are represented by a straight line with a smaller slope than that of the linear action region Lnr.

[0223] Furthermore, in the stroke X= X0 , the contact portion 72 a may not be completely received in the fixing portion 71 .

[0224] When the working pressure P rises from Ps1, the movable portion 72 in the stroke X=X0 extends from the stroke end. While the working pressure P rises from Ps1 to Pn1, the stroke X changes along the straight line shown in the region Sbr. While the working pressure P rises from Pn1 to Pn2, the stroke X is maintained at Xc along the straight line shown in the nonlinear action region NL. While the working pressure P rises from Pn2 to Pt, the stroke X changes from Xc to Xt along the straight line shown in the linear action region Lnr. When the working pressure P rises from Pt, the stroke X increases compared to Xt, and the contact portion 72a presses the movable valve portion 54.

[0225] The spring constant of the stroke buffer spring 74 as the nonlinear motion imparting mechanism 770 is smaller than the spring constant of the retraction spring 73. The stroke buffer spring 74 has only a weaker elastic force than the retraction spring 73.

[0226] Therefore, at a position near the stroke end where the stroke X is the initial value X0, the working pressure P can be used as the initial pressure Ps1 to apply a small working pressure. Furthermore, when the working pressure P is in the range of Ps1 to Pn1, the stroke buffer spring 74 expands and contracts, but the retraction spring 73 does not expand and contract. On the other hand, when the working pressure P is in the range of Pn2 to Pt, not only the stroke buffer spring 74 expands and contracts, but also the retraction spring 73 expands and contracts.

[0227] Here, between the point NL1 (Xc, Pn1) and the point NL2 (Xc, Pn2), the pressing drive unit 70 does not continuously perform linear motion, and the stroke X relative to the operating pressure P performs nonlinear motion.

[0228] Therefore, even if there are deviations in the positions or movements of the plurality of movable parts 72 before the movement, all the movable parts 72 move together by passing through the nonlinear motion region NL.

[0229] Figure 5 2 is a schematic cross-sectional view showing a push drive unit without a nonlinear motion imparting mechanism. Figure 5 In, with Figure 3 The same reference numerals are used for corresponding structures and their description is omitted.

[0230] Figure 6 : is a PX diagram showing the operation of a push drive unit without a nonlinear operation imparting mechanism. Figure 6 , the horizontal axis X also represents the stroke (extension length) of the movable portion 72 of the push drive portion not having the nonlinear motion imparting mechanism, and the vertical axis P also represents the operating pressure P applied to the push drive portion not having the nonlinear motion imparting mechanism.

[0231] exist Figure 5 2 shows a push drive unit 70 that does not include a non-linear motion imparting mechanism.

[0232] Regarding the push drive unit 70 that does not have a nonlinear motion imparting mechanism, Figure 6 As shown, at the stroke end where the stroke X=X0, the working pressure P is the initial pressure Ps1. In addition, the stroke end is the limit position of the movable part 72 in the retracting direction. The typical initial pressure Ps1 value and the working pressure P value are the values ​​caused by the elastic deformation of each retraction spring 73 under each X.

[0233] In the push drive unit 70 which does not have a nonlinear motion imparting mechanism, as Figure 6As shown, the movable part 72 performs linear motion in the entire range of the stroke X from the initial position X0 to the abutment position Xt. More specifically, the movable part 72 performs linear motion in a state where the coincidence principle (the overlap principle of multiple linear equations) of the working pressure P value and the elastic deformation of each retraction spring 73 at each stroke X holds true. The movable part 72 performs linear motion in the entire range of the working pressure P from the initial pressure Ps1 to the abutment pressure Pt.

[0234] In all ranges from X0 to Xt, the stroke X and the working pressure P satisfy Figure 6 The linear relationship of the straight line Lnr is shown.

[0235] In the push drive unit 70 which does not have a nonlinear motion imparting mechanism, as Figure 6 As shown, there is no nonlinear action region NL where nonlinear action is performed.

[0236] Here, a case where a plurality of pressing drive units 70 are driven will be discussed.

[0237] The plurality of push drive parts 70 are all of the same structure. Therefore, when the working pressure P rises from the initial pressure Ps1, the working pressure P rises at the same rate in the plurality of push drive parts 70. Therefore, it is ideal that the plurality of push drive parts 70 extend at the same stroke X value relative to the rise in the working pressure P.

[0238] However, although the plurality of push drive parts 70 have the same structure, they may perform different operations depending on factors that hinder the telescopic operation, such as the lubrication state of the movable part 72 and the friction from the seal part 76 .

[0239] Consider the balance equation of the movable part 72. Figure 6 As shown, when the elastic force from the retraction spring 73 is set to F1, the force from the working fluid as the working pressure P is set to F2, and the static friction force is set to F4, the balance equation related to the force applied to the movable part 72 at the stroke end is as follows.

[0240] F1+F2-F4=0

[0241] Here, the retracting direction of the movable portion 72 is assumed to be positive. In addition, regarding the static friction force F4, the sign thereof may be reversed depending on the operation history of the movable portion 72.

[0242] Based on the factors that hinder the telescopic operation inferred from the above equation, it is considered that there are some push drive parts 70 that are not telescopic when the working pressure P increases. Then, the working fluid to be supplied to the push drive parts 70 that are not operating flows into the push drive parts 70 that are operating.

[0243] Furthermore, among a plurality of pressing drive units 70 having the same structure, the magnitude of the factor that hinders the telescopic operation, that is, the ease with which the movable unit 72 can be telescoped may differ for each pressing drive unit 70 .

[0244] Here, when the magnitude of the factor that hinders the telescopic action is different among the plurality of push drive units 70, the push drive unit 70 with the smallest factor that hinders the telescopic action starts to operate first. At this time, the working fluid that should be supplied to the other push drive units 70 that are not operating flows into the one push drive unit 70 that is operating.

[0245] Therefore, the amount of working fluid flowing into one operating pressing drive unit 70 becomes equal to the total volume of all other pressing drive units 70. Therefore, only the one pressing drive unit 70 protrudes greatly.

[0246] That is, due to the factor that hinders the telescopic action, it is possible that only one push drive unit 70 protrudes compared to the position when each cylinder body protrudes equally. That is, it is possible to move to the abutment position Xt, which is the position where the stroke X of the push drive unit 70 interferes with the valve opening shielding position. This means that the push drive unit 70 intrudes into the distance (gap) that enables the valve body 5 to rotate between the retreat position and the valve opening shielding position. As a result, there is a possibility that the rotation operation of the valve body 5 is hindered due to the protrusion of the movable part 72 that constructs the push drive unit 70. In the case where the valve body is moved by the increase of the working pressure P and all other push drive units 70 rise to the abutment pressure Pt, there is no action to rotate the valve body 5 between the retreat position and the valve opening shielding position. Therefore, the phenomenon that only this one push drive unit 70 protrudes significantly will not become a factor that hinders the telescopic action. However, it is believed that there are cases where this phenomenon occurs, for example, due to the thermal expansion of the working fluid caused by changes in ambient temperature such as heat drying. That is, the plurality of push drive parts 70 cannot perform a simulated action in which the plurality of movable parts 72 protrude equally. That is, one movable part 72 may protrude more than the other movable parts 72, thereby hindering the rotation of the valve body 5.

[0247] exist Figure 5 In the push drive unit 70 shown without the nonlinear motion imparting mechanism, it is considered that in the entire range of the operating pressure P from the contact pressure Pt to the initial pressure Ps1, the plurality of push drive units 70 may not be able to perform a simulated motion with the same stroke X.

[0248] In contrast, in the gate valve 100 of the present embodiment, Figure 4 As shown, all the pressing drive parts 70 pass through the nonlinear motion region NL caused by the nonlinear motion imparting mechanism 770 when the operating pressure P increases from the initial pressure Ps1.

[0249] Therefore, even if there is a deviation in the stroke X within the range where the working pressure P is less than Pn2, the working pressure contributed by the first protruding pushing driving unit 70 increases nonlinearly due to the plurality of pushing driving units 70 passing through the nonlinear action region NL, thereby promoting the protrusion of the subsequent pushing driving unit 70. According to this effect, in the region near the position passing through the point NL2 (Xc, Pn2) due to the increase in the working pressure P, the actions of the plurality of pushing driving units 70 become consistent, and the protrusion is not biased to the linear region Lnr side where the working pressure P is greater than Pn2, and the protrusion amount of all the pushing driving units 70 can be made consistent.

[0250] Next, the operation of the plurality of pressing drive units 70 in the non-linear operation region NL will be described in detail.

[0251] For example, consider a case where the stroke X of the plurality of pressing drive units 70 increases from the stroke end.

[0252] Here, for the sake of explanation, the plurality of push drive parts 70 are respectively divided into a push drive part 70A, a push drive part 70B, and a push drive part 70C. The push drive part 70A can be referred to as a first push drive part. The push drive part 70B can be referred to as a second push drive part. The push drive part 70C can be referred to as a third push drive part.

[0253] In these multiple pushing drive units 70, consider the case where there are differences in the levels of obstruction to the movement of the multiple pushing drive units 70 within the range of stroke X being X0≤X≤Xc. Consider the case where the magnitude (degree) of the level of obstruction to the movement increases in the order of the pushing drive unit 70A, the pushing drive unit 70B, and the pushing drive unit 70C. That is, the level of obstruction to the movement in the pushing drive unit 70A is the smallest. The level of obstruction to the movement in the pushing drive unit 70C is the largest. The so-called "movement obstruction" is typically a stick-slip phenomenon, and the sticking phenomenon in the pushing drive unit is observed as a cause of obstruction to the movement of the pushing drive unit.

[0254] First, the operating pressure P rises from Ps1.

[0255] The operating pressure P increases as the operating oil is supplied to the plurality of pressing drive parts 70 by the driving pressure generating mechanism 701. In the plurality of pressing drive parts 70, an expansion operation is performed along the region Sbr in response to the inflow of the operating oil.

[0256] However, since the levels of the obstruction actions in the plurality of push drive units 70 are different, the movable portion 72 first extends in the push drive unit 70A having the smallest level of obstruction action. At this time, the movable portion 72 does not extend in the push drive units 70B and 70C.

[0257] During the period when the working oil flows into the pushing drive unit 70A as the working pressure P rises, the working oil does not flow into the other pushing drive units 70B and 70C. That is, all the working oil supplied by the drive pressure generating mechanism 701 flows into the pushing drive unit 70A with the lowest level of hindering action. The stroke X of the pushing drive unit 70A further increases by an amount corresponding to the inflow volume of the working oil that should originally flow into the pushing drive units 70B and 70C.

[0258] Since the working oil does not flow into the pushing drive units 70B and 70C with a large level of hindering action, as the working pressure P rises, only the pushing drive unit 70A extends significantly.

[0259] Therefore, before the working pressure P reaches Pn1, it is possible that only the pushing drive unit 70A reaches the stroke X = Xc first as the working pressure P rises. As the working pressure P rises, only the pushing drive unit 70A reaches the non-linear action region NL first.

[0260] At this time, the pushing drive units 70B and 70C do not reach the stroke X = Xc. The pushing drive units 70B and 70C are within the range of the stroke X < Xc.

[0261] When only the pushing drive unit 70A reaches the non-linear action region NL above the stroke Xc first, the working pressure P rises non-linearly. Due to this pressure rise, the pushing drive units 70B and 70C overcome the factors hindering the action and start to extend along the region Sbr. At this time, according to the level of hindering action, for example, after the pushing drive unit 70B starts to extend, the pushing drive unit 70C starts to extend.

[0262] Then, the working oil flows into the pushing drive units 70B and 70C, and the extension action of the pushing drive unit 70A is alleviated.

[0263] As the working pressure P rises, the pushing drive units 70B and 70C reach the positions corresponding to the working pressure P (for example, the stroke X = Xc). When the pushing drive units 70B and 70C reach the non-linear action region NL, the working pressure P is greater than Pn1. During this period, the working oil flows into the pushing drive units 70B and 70C, maintaining the state where the extension action of the pushing drive unit 70A is alleviated.

[0264] That is, since the pressing drive unit 70A that first performs the elongation operation reaches the non-linear operation region NL, the working pressure P rises non-linearly. As a result, the strokes X of the pressing drive units 70B and 70C that start the elongation operation later reach positions near the stroke X position of the pressing drive unit 70A. Therefore, the effect that the strokes X of the pressing drive unit 70A, the pressing drive unit 70B, and the pressing drive unit 70C are consistent is obtained.

[0265] If the working pressure P further rises in the non-linear operation region NL, during the period when the working pressure P rises to Pn2, the effect that the strokes X of the pressing drive unit 70A, the pressing drive unit 70B, and the pressing drive unit 70C become further consistent is generated. That is, in the non-linear operation region NL, during the period when Pn1 < P < Pn2 for the working pressure P, the plurality of pressing drive units 70 can be adjusted so as to have the same stroke Xc.

[0266] Preferably, when the working pressure P reaches Pn2, the operations of all the pressing drive units 70 are consistent. That is, it is preferable to determine the value of Pn2 such that the elongation positions of all the pressing drive units 70 are consistent on the stroke X = Xc. More specifically, it is preferable to determine the value of Pn2 such that each pressing drive unit 70 can function individually.

[0267] When the working pressure P rises and exceeds Pn2, all the pressing drive units 70 with consistent operations simultaneously reach the linear operation region Lnr. When exceeding Xc in the linear operation region Lnr, all the pressing drive units 70 with consistent operations perform linear operations with the same stroke X.

[0268] Therefore, when the stroke X is the contact position Xt, the contact portions 72a of all the pressing drive units (the pressing drive unit 70A, the pressing drive unit 70B, the pressing drive unit 70C) simultaneously reach the movable valve portion 54. All the pressing drive units 70 can perform consistent operations with respect to the working pressure P. Therefore, an abnormal situation where some of the pressing drive units protrude and others do not protrude does not occur. That is, the rotational operation of the valve body 5 is not hindered.

[0269] In addition, when the working pressure P further rises and exceeds the linear operation region Lnr, the contact portions 72a of the pressing drive unit 70A, the pressing drive unit 70B, and the pressing drive unit 70C simultaneously press the movable valve portion 54.

[0270] In this way, as the working pressure P rises and passes through the non-linear operation region NL, the pressing drive units 70 whose operations are not hindered move smoothly together.

[0271] Next, consider the case where the stroke X of the plurality of pressing drive units 70 decreases from the contact position Xt.

[0272] In this case, there are fewer problems compared to the case where the stroke X of each push drive unit 70 is increased (the case where the push drive unit 70 is operated from a stationary state). This is because in the range of the working pressure P from Pt to Pn2, the influence of the working pressure P is more dominant than the factors that hinder the operation of each push drive unit 70, and the dynamic friction coefficient is smaller than the static friction coefficient, so the factors that hinder the operation of each push drive unit 70 are smaller.

[0273] Next, consider the case where the gate valve 100 is heated up.

[0274] Figure 7 : is an XV diagram showing the operation of a push drive unit without a nonlinear operation imparting mechanism. Figure 7 In FIG. 1 , the vertical axis X represents the stroke (extension length) of the movable portion 72 of the push drive portion without the nonlinear motion imparting mechanism, and the horizontal axis V represents the volume V of the working fluid flowing out of and into the push drive portion without the nonlinear motion imparting mechanism.

[0275] Regarding the push drive unit 70 that does not have a nonlinear motion imparting mechanism, as in Figure 7 As indicated by the solid line Lnr in FIG. 1 , the volume V of the inflowing working fluid and the stroke X are in a linear relationship.

[0276] When the gate valve 100 is heated up due to changes in the ambient temperature, the hydraulic drive device 700 is heated up. The filled working fluid is heated by the temperature increase of the hydraulic drive device 700. The heated working fluid undergoes thermal expansion. The working fluid is filled into a closed loop formed by the pipe 702, the drive pressure generating mechanism 701, and the push drive portion 70. Therefore, under the condition that the volume of the system other than the movable portion 72 does not change, the movable portion 72 serving as a piston is pushed in the push drive portion 70 in accordance with the volume after thermal expansion. That is, due to thermal expansion, the same phenomenon as the case where the pressure P of the inflowing working fluid increases occurs in the push drive portion 70. Due to thermal expansion, the movable portion 72 is expanded as in Figure 7 The movement ΔXb in the direction of elongation is represented by Lnr+.

[0277] When the gate valve 100 cools down, the volume of the working fluid also decreases. Due to the thermal contraction, the same phenomenon as when the pressure P of the inflowing working fluid decreases occurs in the push drive unit 70. Due to the thermal contraction, the movable unit 72 moves as in Figure 7 The movement in the retreat direction ΔXb is represented by Lnr-.

[0278] In the case where the above-mentioned factors hindering the operation are the same in the plurality of pushing drive units 70, all the pushing drive units 70 may be affected by the volume change caused by heat. Figure 7As shown in FIG. 1 , the movable part 72 moves in the direction in which the stroke X changes. That is, when the working pressure P is the initial pressure Ps1, the stroke X moves from the initial position X0 due to thermal expansion or thermal contraction. In particular, when thermal expansion occurs, the movable part 72 moves in the direction in which the stroke X extends from the initial position X0.

[0279] If the factors hindering the motion are not equal, and the plurality of push drive parts 70 are push drive parts without a nonlinear motion imparting mechanism, then, as described above, only the push drive part 70 that is most easily movable among the plurality of push drive parts 70 will extend. That is, when the working pressure P is the initial pressure Ps1, only the push drive part 70 with the smallest factor hindering the motion may extend significantly due to the thermal expansion of the working fluid.

[0280] In the push drive unit without the nonlinear motion imparting mechanism, the movable portion 72 may protrude due to the temperature rise regardless of the operating position of the valve body 5. That is, the push drive unit 70 that is most easily movable may intrude into the distance (gap) that allows the valve body 5 to rotate between the retreat position and the valve opening shielding position, and the movable portion 72 of the push drive unit 70 may protrude, thereby hindering the rotation of the valve body 5.

[0281] In contrast, in the gate valve 100 of the present embodiment, as described above, the nonlinear motion imparting mechanism 770 allows the plurality of push drive parts 70 to simulate an extension motion. That is, even in the case of thermal expansion such as the stroke X moving from the initial position X0 to the protruding direction, all of the plurality of push drive parts 70 pass through the nonlinear motion region NL, so that there will not be a situation where only one push drive part 70 tends to protrude. All the push drive parts 70 simulate an extension motion relative to the movable valve part 54. Thus, a distance (gap) that allows the valve body 5 to rotate between the retreat position and the valve opening shielding position can be ensured. Therefore, the nonlinear motion imparting mechanism 770 can suppress the influence of thermal expansion caused by the increase in the stroke X of the plurality of push drive parts 70 within the range where the working pressure P is less than Pn1.

[0282] The gate valve 100 of this embodiment has a nonlinear motion imparting mechanism 770. Thus, for the extension motion of the stroke X of the plurality of push drive parts 70 moving from the initial position X0 to the protruding direction, the stroke X values ​​of the push drive parts 70 can be made consistent at positions near Xc. The nonlinear motion imparting mechanism 770 can perform a nonlinear motion that can adjust the protruding amount of the plurality of push drive parts 70 without contacting the valve body 5.

[0283] Thus, the push drive unit 70 pushes the valve body 5, and the valve body 5 can smoothly move to the position of sealing the opening. By smoothly releasing the pushing state of the valve body 5, the sealing of the opening can be released, and the valve body 5 can move to the position where it can rotate.

[0284] The nonlinear motion imparting mechanism 770 can simultaneously realize a state in which the movable parts 72 of all the pushing drive parts 70 are sufficiently away from the valve body 5 during the extension and contraction of the pushing drive part 70. Thus, the rotation of the valve body 5 is not hindered by the protrusion of the movable part 72.

[0285] When the working fluid (working oil) undergoes thermal expansion, the nonlinear motion imparting mechanism 770 can prevent the movable portion 72 from accidentally contacting the valve body 5. Alternatively, when the level of factors hindering the movement, such as adhesion of the push drive portion 70, friction with the seal portion 76, etc., increases, or when the level of factors hindering the movement varies, the nonlinear motion imparting mechanism 770 can maintain a necessary gap.

[0286] In addition, in the present embodiment, the nonlinear motion region NL is formed by the nonlinear motion imparting mechanism 770 when the stroke X is Xc. In the present invention, the stroke X that forms the nonlinear motion region NL is not particularly limited. For example, as long as the stroke X is between X0 and Xc, that is, as long as the stroke X is in the interval from when the movable part 72 starts the extension motion to when it forms the linear motion region Lnr, the stroke X that forms the nonlinear motion region NL is not particularly limited.

[0287] Figure 8 : is a PX chart showing another example of the operation of the push drive unit of this embodiment. In addition, this embodiment may be configured as follows: Figure 8 As shown, the nonlinear action area NL is represented by the working pressure P that is consistent with Pn1 and Pn2. Figure 3 The structure in which the retraction spring 73 in the nonlinear operation region NL is not pressurized. That is, as a typical example, the state in which the end of the retraction spring 73 close to the movable portion 72 is located at the locking portion 73r is the free length of the retraction spring 73. The nonlinear operation region NL is represented by the point NL (Xc, Pn). In this case, the operations of the plurality of push drive units 70 become consistent by passing through the point NL (Xc, Pn). Here, the upper limit point NL2 (Xc, Pn2) and the lower limit point NL1 (Xc, Pn1) in the nonlinear operation region NL coincide with the point NL (Xc, Pn).

[0288] The nonlinear operation point NL can be set according to, for example, the position of the locking portion 73 r , the spring constants of the stroke buffer spring 74 and the return spring 73 , and the amount of pressure increase of the stroke buffer spring 74 .

[0289] Furthermore, in the present embodiment, the nonlinear motion imparting mechanism 770 is a double spring structure having a stroke buffer spring 74 whose coil diameter is smaller than the coil diameter of the retraction spring 73 and whose wire diameter is smaller. The present invention is not limited to such a structure. As the nonlinear motion imparting mechanism 770, a structure having a stroke buffer spring connected to the retraction spring 73 and having nonlinear characteristics may also be adopted.

[0290] In this case, in the nonlinear motion imparting mechanism 770, the stroke buffer springs may be formed at both ends of the retraction spring 73. As the stroke buffer spring structure, a coil spring structure which is integrated with the retraction spring 73 and has nonlinear characteristics may be adopted.

[0291] In the stroke buffer spring of this example, a tapered wire can be used. The tapered stroke buffer spring is a unequal coil diameter portion where the wires do not contact each other when a load is applied. The stroke buffer spring of this typical example is a conical spring, a drum spring, or a barrel spring. In the case of this example, the stroke buffer spring and the retraction spring 73 may also be integrated into one structure.

[0292] In this example, Figure 4 The nonlinear operation region NL shown is represented by a curve connecting point NL1 (Xc, Pn1) and point NL2 (Xc2, Pn2), wherein Xc2 is a stroke X greater than Xc.

[0293] Furthermore, as a nonlinear spring changed to the above structure, the pitch, coil diameter, and wire diameter can be changed.

[0294] <Second Embodiment>

[0295] Next, a gate valve according to a second embodiment of the present invention will be described with reference to the drawings.

[0296] Fig. 9 2 is a schematic cross-sectional view showing a gate valve of this embodiment. This embodiment differs from the first embodiment in the nonlinear motion imparting mechanism 770. The same reference numerals are used for the components corresponding to the first embodiment other than the nonlinear motion imparting mechanism 770, and their description is omitted.

[0297] like Fig. 9 As shown, the nonlinear motion imparting mechanism 770 of this embodiment is a telescopic piston 740 disposed in the pipe 702. In this embodiment, the stroke buffer spring 74 and the locking portion 73r are not disposed in the fixing portion 71.

[0298] The telescopic piston 740 includes a moving piston 741a, a moving piston 741b, and a stroke buffer spring 744. The moving piston 741a is an example of a first piston member. The moving piston 741b is an example of a second piston member. The stroke buffer spring 744 is an example of an elastic portion.

[0299] The movable piston 741a and the movable piston 741b are both accommodated in the pipe 702. The movable piston 741a and the movable piston 741b are of the same diameter as the pipe 702. The movable piston 741a and the movable piston 741b are both freely movable in the pipe 702 along the moving direction of the working oil. The movable piston 741a and the movable piston 741b are spaced apart from each other in the moving direction of the working oil in the pipe 702. The distance between the movable piston 741a and the movable piston 741b in the moving direction of the working oil can be changed.

[0300] A stroke buffer spring 744 is disposed between the moving piston 741a and the moving piston 741b. The stroke buffer spring 744 is an example of a nonlinear mechanism for starting the operation. In addition, the stroke buffer spring 744 is an example of an elastic mechanism.

[0301] The travel buffer spring 744 connects the moving piston 741a and the moving piston 741b. The travel buffer spring 744 can be extended and retracted along the moving direction of the working oil in the pipe 702. The travel buffer spring 744 can apply a force to the moving piston 741a and the moving piston 741b.

[0302] The stroke buffer spring 744 is a weak spring similar to the stroke buffer spring 74 in the first embodiment. The stroke buffer spring 744 corresponds to the stroke buffer spring 74 in the first embodiment.

[0303] The nonlinear motion imparting mechanism 770 in this embodiment corresponds to the structure in which the stroke buffer spring 74 is arranged on the side opposite to the retraction spring 73 in the fixed portion 71 in the first embodiment. That is, the present embodiment corresponds to the structure in which the retraction spring 73 and the stroke buffer spring 744 are arranged in series and an elastic force is applied to the movable portion 72. The present embodiment can be said to be an example in which the nonlinear spring of the first embodiment is constructed by the stroke buffer spring 744 and the retraction spring 73.

[0304] The telescopic piston 740 is immersed in the working fluid in the pipe 702. The outside of the telescopic piston 740 in the pipe 702 is filled with the working fluid. That is, the pipe 702 closer to the driving pressure generating mechanism 701 than the moving piston 741a and the pipe 702 closer to the pushing driving unit 70 than the moving piston 741b are both filled with the working fluid. The inside of the telescopic piston 740 is not filled with the working fluid.

[0305] In this embodiment, the telescopic piston 740 transmits the working pressure P applied to the push drive unit 70 by the drive pressure generating mechanism 701 in the pipe 702 .

[0306] The working pressure P transmitted by the moving piston 741a is applied to the pushing drive portion 70 via the stroke buffer spring 744 and the moving piston 741b. Similarly, the working pressure P transmitted by the moving piston 741b is applied to the driving pressure generating mechanism 701 via the stroke buffer spring 744 and the moving piston 741a.

[0307] At this time, the stroke buffer spring 744 is elastically deformed according to the working pressure P.

[0308] That is, when the working fluid is supplied from the driving pressure generating mechanism 701 to the pipe 702, the working pressure P is applied to the moving piston 741a corresponding to the supplied volume of the working fluid. The telescopic piston 740 moves in the pipe 702 corresponding to the supplied volume of the working fluid. At this time, the stroke buffer spring 744 is telescopic according to the working pressure P. Further, the working pressure P is transmitted to the moving piston 741b via the stroke buffer spring 744. The moving piston 741b pushes the working fluid.

[0309] At the same time, the telescopic piston 740 moves the working fluid in the pipe 702 toward the pressing drive unit 70 according to the supplied volume of the working fluid and the telescopic length of the stroke buffer spring 744. Thus, the working fluid is supplied to the fixed portion 71 of the pressing drive unit 70.

[0310] In this embodiment, Figure 4 In the first embodiment shown, the plurality of push drive units 70 are caused to pass through the nonlinear motion region NL by the nonlinear motion imparting mechanism 770. Thus, the motions of the plurality of push drive units 70 can be made consistent, thereby preventing the occurrence of irregular protrusions.

[0311] In this embodiment, the same effects as those of the above-mentioned embodiment are obtained. Furthermore, in this embodiment, the effect of enabling the plurality of pressing drive units 70 to perform a simulated operation is obtained simply by disposing the telescopic piston 740 in the pipe 702 .

[0312] In addition, the telescopic piston 740 may be configured to be closer to the push drive unit 70 than the position where the pipe 702 branches from the drive pressure generating mechanism 701 to each of the plurality of push drive units 70. The telescopic piston 740 may be configured to be closer to the drive pressure generating mechanism 701 than the position where the pipe 702 branches from the drive pressure generating mechanism 701 to each of the plurality of push drive units 70.

[0313] Furthermore, as the elastic part in the telescopic piston 740, a compressible fluid or the like filled between the two movable pistons 741a and 741b (piston member) may be provided instead of the stroke buffer spring 744. The compressible fluid may be, for example, air. Since the compressible fluid is elastically deformed with respect to the compressive force, it can perform the same action as the stroke buffer spring 744.

[0314] <Third Embodiment>

[0315] Next, a gate valve according to a third embodiment of the present invention will be described with reference to the drawings.

[0316] Fig.10 2 is a schematic cross-sectional view showing a gate valve of this embodiment. This embodiment differs from the second embodiment in the nonlinear motion imparting mechanism 770. The same reference numerals are used for the components corresponding to the second embodiment other than the nonlinear motion imparting mechanism 770, and their description is omitted.

[0317] like Fig.10 As shown in FIG. 1 , the nonlinear motion imparting mechanism 770 of the present embodiment is an accumulator 701 a . In the present embodiment, the stroke buffer spring 74 and the locking portion 73 r are not arranged in the fixing portion 71 .

[0318] The accumulator 701a is an elastic pressure regulating mechanism with an air intake stroke. The accumulator 701a is an example of a nonlinear mechanism for starting an action. The elastic pressure regulating mechanism is an example of another circuit. The accumulator 701a has, for example, a movable cover type tank with a built-in spring. When the working fluid is supplied from the driving pressure generating mechanism 701, the accumulator 701a mitigates the rise of the working pressure P and enables the push drive unit 70 to perform a nonlinear action. The accumulator 701a forms a region Sbr and a nonlinear action region NL.

[0319] The rise of the working pressure P mitigated by the accumulator 701a corresponds to the stroke buffer spring 74 in the first embodiment. The built-in spring of the accumulator 701a is a weak spring like the stroke buffer spring 74 in the first embodiment. This embodiment can be said to be an example of constructing the nonlinear spring of the first embodiment by the accumulator 701a and the retraction spring 73.

[0320] In this embodiment, Figure 4 In the first embodiment shown, the plurality of push drive units 70 are caused to pass through the nonlinear motion region NL by the nonlinear motion imparting mechanism 770. Thus, the motions of the plurality of push drive units 70 can be made consistent, thereby preventing the occurrence of irregular protrusions.

[0321] In the present embodiment, the points NL1 (Xc, Pn1) and NL2 (Xc, Pn2) in the nonlinear action region NL can be set by the set pressure of the built-in spring at the upper limit of the absorption volume of the accumulator 701a.

[0322] In this embodiment, the same effects as those of the above-mentioned embodiment are obtained.

[0323] In addition, the accumulator 701a may be connected to the pipe 702 which is closer to the pushing drive unit 70 than the position where the pipe 702 branches from the driving pressure generating mechanism 701 to each of the plurality of pushing drive units 70. The accumulator 701a may be connected to the pipe 702 which is closer to the driving pressure generating mechanism 701 than the position where the pipe 702 branches from the driving pressure generating mechanism 701 to each of the plurality of pushing drive units 70.

[0324] <Fourth Embodiment>

[0325] Next, a gate valve according to a fourth embodiment of the present invention will be described with reference to the drawings.

[0326] Fig.11 2 is a schematic cross-sectional view showing a gate valve of this embodiment. This embodiment differs from the first and second embodiments in the nonlinear motion imparting mechanism 770. The same reference numerals are used for the structures corresponding to the second embodiment other than the nonlinear motion imparting mechanism 770, and their description is omitted.

[0327] like Fig.11 As shown, the nonlinear motion imparting mechanism 770 of this embodiment is a bubble Bb arranged in the pipe 702 instead of the telescopic piston 740 of the second embodiment. The bubble Bb is an example of an elastic fluid. In this embodiment, the stroke buffer spring 74 and the locking portion 73r are not arranged in the fixing portion 71.

[0328] The bubble Bb is a structure corresponding to the space portion between the moving piston 741a and the moving piston 741b in the telescopic piston 740 of the second embodiment. The bubble Bb has a function of starting the nonlinear mechanism. The bubble Bb is a structure having an elastic force corresponding to the stroke buffer spring (elastic portion) 744 of the second embodiment. This embodiment can be said to be an example in which the nonlinear spring of the first embodiment is constructed by the bubble Bb and the retraction spring 73.

[0329] Alternatively, the nonlinear action imparting mechanism 770 of the present embodiment corresponds to the following structure: that is, the structure is a structure in which the stroke buffer spring 744 serving as the elastic part in the telescopic piston 740 of the second embodiment is replaced by a compressible fluid or the like filled between the two movable pistons 741a, 741b, and in such a structure, the two movable pistons 741a, 741b are not provided.

[0330] The air bubble Bb is contained in the pipe 702. The air bubble Bb is formed to have a diameter equal to the diameter of the pipe 702. As long as the air bubble Bb is formed in the pipe 702, its diameter may be smaller than the diameter of the pipe 702. The air bubble Bb can move freely in the pipe 702 along the moving direction of the working oil. The volume of the air bubble Bb may change in the pipe 702.

[0331] The air bubble Bb is immersed in the working fluid in the pipe 702. In the pipe 702, the outside of the air bubble Bb is filled with the working fluid. The air bubble Bb is a compressible gas sealed inside the pipe 702 according to the set working pressure P. Alternatively, the air bubble Bb may be air appropriately selected according to the operating conditions of the gate valve 100. In particular, the air bubble Bb may be selected according to the vapor pressure of the working fluid, etc. As for the air bubble Bb, a non-reactive gas such as nitrogen or argon may be selected according to the reactivity with the working fluid.

[0332] In addition, the sealing pressure of the bubble Bb can be selected according to the vapor pressure of the working fluid, the operating temperature of the gate valve 100, etc. The sealing pressure of the bubble Bb can be set to be the same as the atmospheric pressure. The sealing pressure of the bubble Bb can be set to be less than the atmospheric pressure. The sealing pressure of the bubble Bb can be set to be greater than the atmospheric pressure.

[0333] The air bubble Bb is a weak spring similar to the stroke buffer spring 744 in the second embodiment.

[0334] The nonlinear motion imparting mechanism 770 in this embodiment corresponds to a structure in which the air bubble Bb as the elastic fluid is arranged on the side opposite to the retraction spring 73 in the fixed portion 71. That is, this embodiment corresponds to a structure in which the retraction spring 73 and the stroke buffer spring 744 are arranged in series in the second embodiment and an elastic force is applied to the movable portion 72.

[0335] In the present embodiment, the volume of the air bubble Bb may expand and contract according to the working pressure P applied from the driving pressure generating mechanism 701 to the inside of the pipe 702 of the pushing driving portion 70 .

[0336] That is, the air bubble Bb exhibits a function equivalent to that of the stroke buffer spring 744 that is elastically deformed according to the operating pressure P.

[0337] In this embodiment, Figure 4 In the first embodiment shown, the plurality of push drive units 70 are caused to pass through the nonlinear motion region NL by the nonlinear motion imparting mechanism 770. Thus, the motions of the plurality of push drive units 70 can be made consistent, thereby preventing the occurrence of irregular protrusions.

[0338] In this embodiment, the same effects as those in the above-mentioned embodiment are obtained. Furthermore, in this embodiment, by simply sealing the air bubble Bb in the duct 702, the effect of enabling the plurality of pressing drive units 70 to perform a simulated operation is obtained without increasing the number of parts.

[0339] In addition, the bubble Bb may be arranged closer to the push drive unit 70 than the position where the pipe 702 branches from the drive pressure generating mechanism 701 to each of the plurality of push drive units 70. The bubble Bb may be arranged closer to the drive pressure generating mechanism 701 than the position where the pipe 702 branches from the drive pressure generating mechanism 701 to each of the plurality of push drive units 70. The bubble Bb may be located in the working fluid of the fixing unit 71. The bubble Bb may also be located in the working fluid of the drive pressure generating mechanism 701.

[0340] <Fifth Embodiment>

[0341] Next, a gate valve according to a fifth embodiment of the present invention will be described with reference to the drawings.

[0342] Fig.12 It is a schematic cross-sectional view showing the gate valve according to the present embodiment. Fig.13 7 is a PX chart showing the operation of the push drive unit in the gate valve of this embodiment. The difference between this embodiment and the third embodiment described above lies in the nonlinear operation imparting mechanism 770. The same reference numerals are used for the structures corresponding to the third embodiment described above except for the nonlinear operation imparting mechanism 770, and their description is omitted.

[0343] The nonlinear motion imparting mechanism 770 of this embodiment replaces Fig.11 The vacuum stroke VS is configured by the air bubble (elastic fluid) Bb in the third embodiment shown in FIG. The vacuum stroke VS is an example of a vacuum region. In this embodiment, a fixed-stroke stop portion 77 is configured in the fixed portion 71. In this embodiment, the stroke buffer spring 74 and the stopper 73r are not configured in the fixed portion 71.

[0344] like Fig.12 As shown, the pressing drive unit 70 of the present embodiment is provided with a fixed-stroke stopper 77 .

[0345] The fixed-stroke stopper 77 is provided at a position where the movable part 72 does not retract any more at the stroke X which becomes the stroke end. That is, the fixed-stroke stopper 77 is provided at a position where the movable part 72 abuts at the stroke end of the movable part 72.

[0346] The fixed-stroke stop portion 77 may be formed to protrude from the bottom of the fixed portion 71 in the extension direction. Alternatively, it may be formed to protrude from the side of the fixed portion 71 in the direction close to the central axis. When the retracted movable portion 72 contacts the fixed-stroke stop portion 77, a space for the working fluid to remain is formed inside the fixed portion 71.

[0347] The operation of the hydraulic drive device 700 according to the present embodiment will be described.

[0348] In this embodiment, the driving pressure generating mechanism 701 as the master cylinder can be operated until the working pressure P becomes a negative pressure.

[0349] Consider the case where the operating pressure P is reduced from the stroke X to the contact position Xt.

[0350] When the working pressure P is reduced, the driving pressure generating mechanism 701 operates to suck the working fluid from the pushing drive unit 70. Typically, the internal volume of the main cylinder in the driving pressure generating mechanism 701 that stores the working fluid is expanded, thereby performing the suction operation of the movable part 72 in each pushing drive unit 70 using the retraction spring 73 as a power source.

[0351] As the working pressure P decreases, in the plurality of push drive parts 70, as shown in the linear action region Lnr, the stroke X of the movable part 72 decreases from the contact position Xt. In the present embodiment, when the working pressure P decreases to Pn2, the movable part 72 contacts the fixed-stroke stop part 77. At this time, the stroke X becomes the end position X0. When the working pressure P reaches Pn2, a space for the working fluid to remain is formed inside the fixed part 71. In this state, the working fluid bears all the forces generated by the retraction spring 73 of the push drive part 70. In this state, the fixed-stroke stop part 77 does not bear the force generated by the retraction spring 73.

[0352] The driving pressure generating mechanism 701 further operates to draw the working fluid from the pushing driving part 70, thereby reducing the working pressure P from Pn2. In synchronization with this, the force generated by the retraction spring 73 of the pushing driving part 70 is gradually transferred from the working fluid to the fixed-stroke stop part 77. Since the fixed-stroke stop part 77 is a rigid body structure, its position does not change. Even if the working pressure P decreases from Pn2, since the movable part 72 abuts against the fixed-stroke stop part 77, the stroke X does not change at the end position X0. That is, as Fig.13 As shown, the working pressure P decreases along the non-linear action region NL represented by a straight line along the P axis.

[0353] When the working pressure P further decreases, the interior of the fixing portion 71 (for example, the gauge pressure) becomes negative pressure. Fig.13As shown in FIG. 1 , the negative pressure state of the working pressure P is located at a position lower than the X axis along the P axis. When the working pressure P is negative pressure, as shown in FIG. Fig.12 As shown, a vacuum stroke (nonlinear mechanism starts to operate) VS is formed inside the fixing portion 71. When the working pressure P becomes negative pressure, for example, the internal volume of the driving pressure generating mechanism 701 is further expanded. Then, the volume of the vacuum stroke VS increases.

[0354] When the decreasing working pressure P reaches Pn1, the driving pressure generating mechanism 701 stops. The working pressure Pn1 is a negative pressure. In the present embodiment, the lower limit of the working pressure P is Pn1. The working pressure P here does not decrease compared to Pn1.

[0355] By adjusting the internal volume of the driving pressure generating mechanism 701 , the volume of the vacuum stroke VS formed can be set.

[0356] In this embodiment, if Fig.13 As shown, the nonlinear action region NL is the range of the working pressure P between the lower limit Pn1 and the upper limit Pn2. The lower limit Pn1 value is, for example, the vapor pressure obtained at the ambient temperature of the working fluid. In the nonlinear action region NL, the stroke X maintains the end position X0. Fig.13 As shown, the nonlinear action region NL is represented by a straight line between the stroke X and the working pressure P in the vertical direction of the longitudinal axis P. The nonlinear action region NL is represented by a straight line between the upper limit point NL2 (X0, Pn2) and the lower limit point NL1 (X0, Pn1). In addition, Pn1<0 (gauge pressure).

[0357] Similarly, consider the case where the working pressure P is increased from the stroke X to the end position X0.

[0358] When the working pressure P is increased, the driving pressure generating mechanism 701 operates to deliver the working fluid to the push drive unit 70. Typically, this operation is an operation to reduce the internal volume of the driving pressure generating mechanism 701, that is, an operation in the same direction as increasing the working pressure P (pressure increasing direction operation).

[0359] First, the volume of the working fluid sent from the driving pressure generating mechanism 701 gradually fills the volume of the vacuum stroke VS. During this operation, the working pressure P generally maintains the lower limit Pn1 value. As the internal volume of the driving pressure generating mechanism 701 decreases, the volume of the vacuum stroke VS decreases.

[0360] After that, the volume of the vacuum stroke VS is filled. The vacuum stroke VS inside the fixing part 71 disappears. From this point in time, the working pressure P can rise from the lower limit Pn1. That is, when the working fluid is supplied to the push drive part 70, the working pressure P rises. At this time, Fig.13As shown, the working pressure P rises along the non-linear action region NL represented by a straight line along the P axis.

[0361] When the working pressure P further increases, the interior of the fixing portion 71 becomes a positive pressure (gauge pressure). When the working pressure P becomes a positive pressure, the working pressure P continues to increase due to the working fluid supplied to the pressing drive portion 70 by the driving pressure generating mechanism 701 .

[0362] When the operating pressure P increases and reaches Pn2, the nonlinear operation region NL ends. While the operating pressure P increases from Pn1 to Pn2, the stroke X is maintained at X0 along the straight line indicated by the nonlinear operation region NL.

[0363] When the operating pressure P increases compared to Pn2 , the movable portion 72 leaves the fixed-stroke stop portion 77 .

[0364] When the working pressure P increases from Pn2, the driving pressure generating mechanism 701 supplies the working fluid to the pressing driving portion 70. During the period when the working pressure P increases from Pn2 to Pt, the stroke X changes from X0 to Xt along the straight line represented by the linear action region Lnr. When the working pressure P increases compared to Pt, the stroke X increases compared to Xt, and the contact portion 72a presses the movable valve portion 54.

[0365] In this embodiment, as in the above-mentioned embodiments, the plurality of pressing drive units 70 are caused to pass through the nonlinear motion region NL by the nonlinear motion imparting mechanism 770. Thus, the motions of the plurality of pressing drive units 70 can be made consistent, thereby preventing the occurrence of irregular protrusions.

[0366] This embodiment can be said to be an example in which the nonlinear spring of the first embodiment is constructed by the retraction spring 73, the fixed stop portion 77, and the vacuum stroke VS.

[0367] In addition, the fifth embodiment is different from the other embodiments in that a dead zone (vacuum stroke VS) is maintained as a nonlinear element. Having a dead zone means that the stroke X does not respond within the dead zone. Specifically, it has a feature that the influence of thermal expansion of the working fluid caused by ambient temperature changes, etc. is not output as the action of the push drive unit 70.

[0368] In this embodiment, the same effect as in the above embodiment is achieved. Furthermore, in this embodiment, the effect of enabling multiple push drive units 70 to perform imitation actions without increasing the number of parts is achieved by only operating the drive pressure generating mechanism 701 until the working pressure P becomes negative pressure.

[0369] In addition, the vacuum stroke VS may be formed at a position filled with the working fluid in the driving pressure generating mechanism 701, the pipe 702, and the plurality of pushing driving parts 70. The position of forming the vacuum stroke VS is not limited as long as the vacuum stroke VS is inside the working fluid.

[0370] Furthermore, in the present invention, each structure in the above-mentioned embodiments may be selected individually and implemented in combination.

[0371] Furthermore, the specifications of the actual device are presented below.

[0372] Total stroke length of the driving pressure generating mechanism 701: 42.2 [mm]

[0373] Volume of vacuum stroke VS: 6.1[mm]

[0374] Aperture of the driving pressure generating mechanism 701: φ15 [mm]

[0375] Total hydraulic oil volume of the driving pressure generating mechanism 701, the pipe 702, and the plurality of push drive units 70: 40436 [mm 3 ]

[0376] · Vacuum volume of the driving pressure generating mechanism 701 that generates negative pressure: 1,078 [mm 3 ]

[0377] Volume expansion rate of working oil (oil): 9.900×10 -4 [1 / ℃]

[0378] ·Temperature rise assumed in gate valve 100: Δ20°C

[0379] Atmospheric pressure (1×10 5 [Pa]) Maximum pressure of the enclosed bubble Bb under compression: 0.4×10 11 [Pa]

[0380] Fig.14 1 shows another structure of the pressing drive unit 70. In this structure, one end surface 771a serves as a fixed-stroke stop portion.

[0381] Further, the movable valve portion of the valve body 5 may also be a structure having a movable valve frame portion (sliding valve disc) and a movable valve disc portion (counter plate). In this structure, the valve closing action can be performed by pushing the movable valve frame portion or the movable valve disc portion by the pushing drive portion 70.

[0382] Description of Reference Numerals

[0383] 5 Valve body

[0384] 10 valve box

[0385] 10b Inner surface

[0386] 12a First opening

[0387] 12b Second opening

[0388] 20 Rotation axis

[0389] 21 Rotation drive unit

[0390] 30 Neutral valve

[0391] 54 movable valve part

[0392] 70 Pushing drive unit

[0393] 71 fixed part (cylinder body)

[0394] 72 movable part (piston)

[0395] 73 Retraction spring

[0396] 74 stroke buffer spring (starting action non-linear mechanism)

[0397] 100 gate valve

[0398] 700 Hydraulic drive unit (incompressible fluid drive unit)

[0399] 701 driving pressure generating mechanism

[0400] 701a Accumulator (elastic pressure adjustment mechanism, another circuit)

[0401] 702 pipeline (oil pressure circuit)

[0402] 770 Nonlinear motion imparting mechanism

[0403] 740 Telescopic piston

[0404] 741a, 741b moving piston

[0405] 744 travel buffer spring (elastic mechanism)

[0406] Bb Bubble

[0407] H channel

[0408] VS vacuum stroke (vacuum area)

Claims

1. A gate valve for blocking a flow channel, comprising: a valve box inserted into the flow channel and having a first opening and a second opening that are opposite to each other and communicate with each other and form the flow channel, a hollow portion between the first opening and the second opening, and a peripheral portion around the first opening; a valve body, located in the hollow portion and capable of opening and closing the flow channel; a rotating shaft supporting the valve body in such a manner that the valve body can rotate in a direction intersecting the flow path between a retreat position in the hollow portion and a valve opening shielding position, and the rotating shaft has an axis extending in the direction of the flow path; A rotation driving unit capable of driving the valve body to rotate; a pushing drive unit, which is disposed in the valve box and is capable of moving the valve body disposed at the valve opening shielding position toward a valve closing position in contact with the peripheral portion in a direction along the flow path, and the pushing drive unit pushes the valve body toward the valve closing position; A driving pressure generating mechanism connected to the pushing driving part and capable of causing the pushing driving part to perform a telescopic action; and The nonlinear motion imparting mechanism can realize a linear motion and a nonlinear motion with respect to the extension and contraction motion of the pressing drive portion driven by the driving pressure generating mechanism.

2. The gate valve according to claim 1, wherein: In the linear motion of the nonlinear motion imparting mechanism, the push drive portion performs a linear motion at a position near the valve closing position where the push drive portion abuts against the valve body, and In the nonlinear motion of the nonlinear motion imparting mechanism, the pressing drive portion performs a nonlinear motion at a position where the pressing drive portion is spaced apart from the valve body.

3. The gate valve according to claim 2, wherein: In the nonlinear motion of the nonlinear motion imparting mechanism, regarding the expansion and contraction motion of the pressing drive portion in a state of being separated from the valve body, the driving pressure generating mechanism causes the pressing drive portion to perform a nonlinear expansion and contraction motion.

4. The gate valve according to claim 3, wherein: The push drive unit includes a retraction spring. The retraction spring retracts the push drive portion that is extended by the increase in the drive pressure generated by the drive pressure generating mechanism. The nonlinear motion imparting mechanism includes an elastic mechanism for retracting the pressing drive portion.

5. The gate valve according to claim 4, wherein: The elastic mechanism is an elastic body having a spring constant different from that of the retraction spring.

6. The gate valve according to claim 5, wherein: The elastic body is a weak spring whose elastic force is smaller than that of the retraction spring and can realize the nonlinear action. The retraction spring is a strong spring having an elastic force greater than that of the elastic body and capable of realizing the linear motion.

7. The gate valve according to claim 6, wherein: The weak spring and the strong spring are arranged in series.

8. The gate valve according to claim 6, wherein: The weak spring and the strong spring are doubly arranged at a coaxial position.

9. The gate valve according to claim 3, wherein: The nonlinear action imparting mechanism comprises a starting action nonlinear mechanism, The nonlinear mechanism for starting the operation can realize the nonlinear operation when the pressing drive portion starts to extend due to the driving pressure generating mechanism.

10. The gate valve according to claim 9, wherein: The nonlinear mechanism for starting the operation comprises one of an elastic mechanism, an elastic pressure adjustment mechanism and an elastic fluid. The elastic mechanism is arranged on a hydraulic circuit connected to the driving pressure generating mechanism and the pushing driving part. The elastic pressure adjustment mechanism is connected to the oil pressure circuit. The elastic fluid is connected to the oil pressure circuit.

11. The gate valve according to claim 9, wherein: The nonlinear mechanism for starting action has a vacuum region, The vacuum region is disposed in a hydraulic circuit configured by connecting the drive pressure generating mechanism and the pressing drive unit.

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