JP6053143B2 - Switchgear - Google Patents

Description

  The present invention relates to an opening / closing device including an opening / closing valve provided in a pipe through which a granular material passes.

  In an apparatus for conveying a granular material such as a resin pellet, an on-off valve may be provided in a pipe through which the granular material passes to control the flow of the granular material. As an on-off valve, a butterfly valve (see, for example, Patent Document 1) composed of a pair of valve shafts rotatably supported by a pipe and a circular valve body, or a slide that moves in a direction perpendicular to the pipe axis direction of the pipe A valve (see FIG. 8) or the like is used.

  Normally, the butterfly type on-off valve is driven by a rotary actuator that operates by air pressure, and the slide type on-off valve is driven by an air cylinder. Conventionally, the air pressure supplied to the actuator (rotary actuator or air cylinder) when driving the open / close valve to the open side and the air pressure supplied to the actuator when driving the open / close valve to the close side are the same magnitude. That's it.

  In addition, when a butterfly valve is used as the on-off valve, when the on-off valve is rotated with the powder in the pipe, the powder is caught between the outer periphery of the valve and the inner surface of the pipe. There was a problem that it was easy. In particular, when switching the open / close valve from the open position to the closed position, the bite between the position where the rotation distance is the longest (the position farthest from the rotating shaft) and the inner surface of the pipe is blocked. It is easy to happen. This biting may cause malfunction such as the on-off valve not moving from the closed position.

  With respect to this problem, in Patent Document 1, in order to suppress the biting of the granular material, the diameter of the valve body is made smaller than the inner diameter of the pipe, and the turning angle of the on-off valve is made less than 90 degrees, When the on-off valve is in the closed position, a gap is formed between the outer peripheral end of the valve body and the inner surface of the pipe. In this gap, the powder particles are supported in an arched structure so that passage of the powder particles is prevented.

JP 2011-27220 A

  However, in Patent Document 1, although the biting of the powder can be suppressed to some extent, the powder may be bitten without forming an arch structure between the outer peripheral end of the valve body and the inner surface of the pipe, The effect of preventing biting was not sufficient.

  When a slide valve is used as the on-off valve, as shown in FIG. 8, if a groove portion 90 a for supporting the tip of the on-off valve 91 is formed on the inner surface of the pipe 90, the on-off valve 91 is closed. When moving to the position, the granular material may be caught between the upper or lower surface of the on-off valve 91 and the inner surface of the groove 90a.

  In view of the above, an object of the present invention is to provide an opening / closing device capable of preventing the powdery body from being caught in the gap between the opening / closing valve and the inner surface of the pipe.

Means for Solving the Problems and Effects of the Invention

The switchgear according to the first aspect of the present invention is arranged in a pipe to which the powder is supplied, and moves between an open state that allows passage of the powder and a closed state that prevents passage of the powder. A possible on-off valve, a fluid pressure actuator having two pressure chambers therein and driving the on-off valve by the pressure of the fluid supplied to the pressure chamber, and a fluid supply for supplying fluid to the two pressure chambers The fluid pressure actuator drives the open / close valve to the open state when fluid is supplied to the first pressure chamber of the two pressure chambers, and the fluid is supplied to the second pressure chamber. the on-off valve is driven to the closed state when the pressure of the fluid supplied to the second pressure chamber is less than the pressure of the fluid supplied to the first pressure chamber, the on-off valve The driving force for driving the closed state opens the open / close valve in the open state. It is configured to be smaller than the driving force for driving,
The fluid supply unit supplies the second pressure chamber with a fluid having a pressure smaller than the pressure of the fluid supplied to the first pressure chamber .

According to this configuration, when the fluid is supplied to the first pressure chamber and the second pressure chamber of the fluid pressure actuator, the on-off valve is driven to the open state and the closed state, respectively, and the pressure of the fluid supplied to the second pressure chamber is Since the pressure of the fluid supplied to the first pressure chamber is smaller, the driving force for driving the on-off valve to the closed state is smaller than the driving force for driving the on-off valve to the open state.
Due to the small driving force that drives the on-off valve to the closed state, when the on-off valve is driven to the closed state with powder particles in the pipe, the granular material is caught between the on-off valve and the inner surface of the pipe. When it is about to be inserted, the on-off valve can stop before the closing limit position of the movable range. Therefore, it is possible to prevent the granular material from being caught between the on-off valve and the inner surface of the pipe, and to prevent the on-off valve from malfunctioning due to the biting of the granular material.
Further, since the driving force for driving the on-off valve to the open state is large, the on-off valve can be reliably driven to the open-side limit position of the movable range even in a state where there are powder particles in the pipe. Therefore, it is possible to ensure a larger flow area of the granular material than when the on-off valve is stopped at the opening limit position, and it is possible to prevent the flow of the granular material from deteriorating.

The opening / closing device according to a second invention is the opening / closing device according to the first invention, wherein the on-off valve is a butterfly valve that can rotate between the open state and the closed state, and the fluid pressure actuator is closed at both ends. A cylindrical body, a shaft penetrating through the internal space of the body and connected to the valve shaft of the butterfly valve, and a vane fixed to the shaft and partitioning the first pressure chamber and the second pressure chamber It is a rotary actuator provided with these.

  According to this configuration, since the on-off valve is configured by a butterfly valve that rotates in the pipe, the shape of the pipe is simplified compared to the case where the on-off valve is configured by a slide valve that moves in a linear direction. it can.

  According to a third aspect of the present invention, there is provided the switchgear according to the first or second aspect, wherein the fluid supply section is a fluid supply path connected to a fluid supply source and a first flow connected to the first pressure chamber. A path, a second flow path connected to the second pressure chamber, a state in which the fluid supply path is in communication with the first flow path, and a state in which the fluid supply path is in communication with the second flow path. And a pressure-reducing valve that is disposed in the middle of the second flow path and depressurizes the pressure of the fluid that has flowed into the second flow path from the fluid supply path.

According to this configuration, when the fluid supply path and the first flow path communicate with each other, the fluid is supplied from the first flow path to the first pressure chamber, the open / close valve is opened, and the fluid supply path and the second flow path are opened. When the passage communicates, fluid is supplied from the second flow path to the second pressure chamber, and the on-off valve is closed. A pressure reducing valve is provided in the middle of the second flow path, and the fluid flowing into the second flow path from the fluid supply path is decompressed by the pressure reducing valve and then supplied to the second pressure chamber. The pressure of the fluid supplied to the pressure chamber can be made smaller than the pressure of the fluid supplied to the first pressure chamber.
Moreover, in this invention, since a fluid is supplied to a 1st pressure chamber and a 2nd pressure chamber from one fluid supply source, cost can be reduced compared with the case where a fluid supply source is provided for every pressure chamber.

It is a schematic block diagram which shows the use condition of the opening / closing apparatus which concerns on embodiment of this invention, Comprising: It is a figure of the state of an open / close valve. FIG. 2 is an enlarged view of an opening / closing valve and a rotary actuator of the opening / closing device shown in FIG. 1. It is sectional drawing along the III-III line of FIG. It is sectional drawing along the IV-IV line of FIG. It is a figure when the on-off valve is switched to the closed position. It is a figure when carrying out suction conveyance of the granular material. It is a schematic block diagram which shows the use condition of the opening / closing apparatus which concerns on other embodiment of this invention, Comprising: (a) is a figure of the state of an on-off valve, and (b) is the state of an on-off valve in a closed position FIG. It is a figure of the opening / closing apparatus provided with the conventional slide type on-off valve.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the opening / closing device 10 of this embodiment is used in a transport device 2 that sucks and transports resin pellets P discharged from a drying hopper 1 to a resin molding machine (not shown).

  The drying hopper 1 is a cylindrical container having a tapered lower portion. A supply unit 1 a for supplying resin pellets P is provided at the upper part of the drying hopper 1, and a discharge port 1 b for discharging the resin pellets P is provided at the lower end of the drying hopper 1. Moreover, although illustration is abbreviate | omitted, dry air is supplied to the dry hopper 1, The resin pellet P stored in the dry hopper 1 is dried with this dry air.

  The transport device 2 includes a pipe 3 connected to the discharge port 1 b of the drying hopper 1, an opening / closing device 10 provided in the pipe 3, a sensor 6 for detecting the presence or absence of the resin pellet P in the pipe 3, The bent pipe 4 connected to the outlet side, the transport path 5 connected to the outlet side of the bent pipe 4, and the gas connected to the outlet side of the transport path 5 and connected to the material supply port of the resin molding machine -It has a granular material separator (illustration omitted) and a suction blower (illustration omitted) connected to the gas granular material separator.

  The pipe 3 is a cylindrical pipe and extends linearly downward from the discharge port 1 b of the drying hopper 1. The bent pipe 4 extends in a straight line after being bent obliquely upward from the lower end of the pipe 3.

  A part of the pipe 3 is composed of a transparent tube 3a, and the sensor 6 is disposed outside the transparent tube 3a. As the sensor 6, for example, a fiber sensor having a projector 6 a and a light receiver 6 b arranged to face each other with the transparent tube 3 a interposed therebetween is used, but other sensors may be used.

  The opening / closing device 10 includes an opening / closing valve 11 disposed in the pipe 3, a rotary actuator 20 that drives the opening / closing valve 11 by air pressure, and an air supply unit 30 that supplies compressed air to the rotary actuator 20.

  The on-off valve 11 is disposed above the transparent tube 3a. As shown in FIG. 2, the on-off valve 11 is configured by a butterfly valve, and includes a disc-shaped valve body 11 a and a pair of valve shafts 11 b that protrude from opposing positions on the outer peripheral surface of the valve body 11 a. . The pair of valve shafts 11b is rotatably supported by the pipe 3. Further, the diameter of the valve body 11 a is smaller than the inner diameter of the pipe 3, and the outer peripheral end of the valve body 11 a does not contact the inner surface of the pipe 3.

  One of the pair of valve shafts 11 b is connected to the shaft 22 of the rotary actuator 20 and rotates integrally with the shaft 22. The on-off valve 11 has a position (open side limit position) in which the valve body 11a is parallel to the pipe axis direction of the pipe 3 (indicated by a broken line in FIG. 3), and a valve body 11a is the pipe axis of the pipe 3 by the rotary actuator 20. It is rotationally driven over a position (closed side limit position) inclined by a predetermined angle θ less than 90 degrees with respect to the direction (indicated by a solid line in FIG. 3). For example, the angle θ is preferably 75 to 85 degrees, and more preferably 80 degrees.

  When the resin pellet P is stored in the drying hopper 1 and the suction blower is not operated, the valve body 11a is in a state (open state) substantially parallel to the pipe axis direction of the pipe 3 and then dried. Resin pellets P that flow into the pipe 3 from the hopper 1 pass through the pipe 3 and are sent to the bent pipe 4. And if the resin pellet P accumulates to the predetermined height of the bending piping 4, the resin pellet P will no longer be discharged | emitted from the inside of the dry hopper 1. FIG.

  In addition, in a state where the resin pellets P are stored in the drying hopper 1 and the suction blower is not operated, the valve body 11a is inclined near the angle θ with respect to the pipe axis direction of the pipe 3 ( 3), the resin pellets P support each other in the gap formed between the entire outer periphery of the valve body 11a and the inner surface of the pipe 3, as shown in FIG. Thus, the passage of the resin pellet P is prevented.

  By forming a gap between the outer peripheral end of the valve body 11a and the inner surface of the pipe 3, when the valve body 11a is rotated from the open state to the closed state, the outer peripheral end of the valve body 11a and the pipe 3 It is possible to suppress the resin pellet P from being bitten between the inner surface and the inner surface. Further, since the rotation angle θ of the valve body 11a is less than 90 degrees, the biting of the resin pellets P can be suppressed more than when θ is 90 degrees.

  As shown in FIGS. 2 and 4, the rotary actuator 20 penetrates through a substantially cylindrical body 21 whose both ends are closed and an internal space of the body 21, and is rotatably supported at both axial ends of the body 21. Shaft 22, vane 23 fixed to shaft 22 and disposed in the internal space of body 21, partition member 24 disposed in the internal space of body 21 and fixed to body 21, and axial direction of body 21 An angle adjusting unit 25 is connected to one end and restricts the rotation angle of the shaft 22.

  The body 21 has two vent holes 21c and 21d communicating with the internal space. The vane 23 is a substantially plate-like member extending from the outer peripheral surface of the shaft 22 in the radial direction of the shaft 22, and the tip thereof is slidably in contact with the inner peripheral surface of the body 21. The partition member 24 is disposed between the openings of the two vent holes 21 c and 21 d on the inner peripheral surface of the body 21, and slidably contacts the outer peripheral surface of the shaft 22.

  The internal space of the body 21 is divided into two pressure chambers 21 a and 21 b by the outer peripheral surface of the shaft 22, the vane 23, and the partition member 24. The first pressure chamber 21a communicates with the first vent hole 21c, and the second pressure chamber 21b communicates with the second vent hole 21d.

  The angle adjustment unit 25 is configured to limit the rotation angle of the shaft 22 to the angle θ. Thereby, the vane 23 rotates between the position shown by the solid line in FIG. 4 and the position shown by the broken line.

  When compressed air is supplied into the first pressure chamber 21a from the first vent 21c, the vane 23 is pressed by the air pressure, and the shaft 22 and the vane 23 rotate counterclockwise in FIG. The air in 21b is discharged from the second vent hole 21d. At this time, the valve body 11a rotates to the open side.

  When compressed air is supplied from the second vent hole 21d into the second pressure chamber 21b, the vane 23 is pressed by the air pressure, and the shaft 22 and the vane 23 rotate clockwise in FIG. 4, and the first pressure chamber 21a. The inside air is discharged from the first vent hole 21c. At this time, the valve body 11a rotates to the closed side.

  The air supply unit 30 includes an air supply path 32 connected to the compressor 31, a first flow path 34 connected to the first ventilation hole 21c, a second flow path 35 connected to the second ventilation hole 21d, The pressure reducing valve 36 provided in the middle of the second flow path 35 and the switching valve 33 disposed between the air supply path 32 and the two flow paths 34 and 35 are provided. The air supply path 32 may be provided with a pressure reducing valve that reduces the pressure of the compressed air supplied from the compressor 31 to a predetermined pressure.

  The switching valve 33 is an electromagnetic switching valve and is controlled by a control device (not shown). As shown in FIG. 1, the switching valve 33 is in a first state in which the air supply path 32 and the first flow path 34 communicate with each other and the second flow path 35 is opened to the atmosphere as shown in FIG. 5, the air supply path 32 and the second flow path 35 communicate with each other, and the first flow path 34 is switched to the second state opened to the atmosphere. Therefore, when the switching valve 33 is in the first state, compressed air is supplied to the first pressure chamber 21a, the on-off valve 11 is opened, and when the switching valve 33 is in the second state, compressed air is supplied to the second pressure chamber 21b. When supplied, the on-off valve 11 is closed.

  The pressure reducing valve 36 provided in the second flow path 35 reduces the pressure of the compressed air supplied from the air supply path 32 to a predetermined pressure. Therefore, the pressure of the compressed air supplied from the second flow path 35 to the second pressure chamber 21b is smaller than the pressure of the compressed air supplied from the first flow path 34 to the first pressure chamber 21a. Therefore, the driving force that drives the on-off valve 11 to the closed state is smaller than the driving force that drives the on-off valve 11 to the open state.

  As an example of the pressure of the compressed air supplied to the pressure chambers 21a and 21b, for example, the pressure of the compressed air supplied to the first pressure chamber 21a is 0.5 MPa, and the compressed air supplied to the second pressure chamber 21b is used. The pressure is 0.2 MPa.

  The magnitude of the pressure of the compressed air supplied to the first pressure chamber 21a is such that the on-off valve 11 is closed from the state where the on-off valve 11 is closed and the passage of the resin pellets P is blocked (the state shown in FIG. 3). Is set so that it can be reliably rotated to the open limit position.

  When the on-off valve 11 is rotated from the open state to the closed state by making the pressure of the compressed air supplied to the second pressure chamber 21b smaller than the pressure of the compressed air supplied to the first pressure chamber 21a, When the on-off valve 11 is just before the closing limit position, the resin pellet P is about to be caught in the gap between the outermost end of the valve body 11a farthest from the rotation shaft and the inner surface of the pipe 3 In addition, since the on-off valve 11 stops without rotating any more, the resin pellet P can be prevented from being caught in the gap between the outer peripheral end of the valve body 11a and the inner surface of the pipe 3.

  Hereinafter, the procedure for transporting the resin pellet P from the dry hopper 1 to the gas / powder separator will be described.

  When the on-off valve 11 is in the closed state (the switching valve 33 is in the second state) and the sensor 6 detects that the resin pellet P is not present in the pipe 3 (transparent pipe 3a), a predetermined time elapses after this detection. The switching valve 33 is switched to the first state. The compressed air that has flowed into the first flow path 34 from the air supply path 32 is supplied to the first pressure chamber 21a. Thereby, as shown in FIG. 1, the on-off valve 11 is opened, the resin pellet P is discharged from the drying hopper 1 to the pipe 3, and the resin pellet P is accumulated in the pipe 3 and the bent pipe 4. When the resin pellets P are accumulated up to the predetermined height of the bent pipe 4, they are no longer discharged from the drying hopper 1.

  After a predetermined time has elapsed since the switching valve 33 was switched to the first state, the switching valve 33 is switched to the second state as shown in FIG. The compressed air flowing into the second flow path 35 from the air supply path 32 is decompressed to a predetermined pressure by the pressure reducing valve 36 and then supplied to the second pressure chamber 21b. As a result, the on-off valve 11 is closed.

  In this state, as shown in FIG. 6, a suction blower (not shown) is operated, and the resin pellet P collected in the bent pipe 4 and the portion on the downstream side of the on-off valve 11 of the pipe 3 is gas / powder. Transport by aspiration to the body separator. When the transport of the resin pellet P is completed, the suction blower is stopped.

  The sensor 6 detects that there is no resin pellet P in the transparent tube 3a during the operation of the suction blower. Thereafter, the series of steps described above is repeated until a necessary amount of resin pellets P are supplied to the resin molding machine.

  It should be noted that the on / off valve 11 is switched to the open state after a lapse of a predetermined time after the sensor 6 detects that the resin tube P is not present in the transparent tube 3a when the resin tube P is present in the transparent tube 3a. At this point, not all the resin pellets P on the downstream side of the on-off valve 11 have been transported to the gas / powder separator, so that all the resin pellets P on the downstream side of the on-off valve 11 This is because the on-off valve 11 is switched to the open state after being transported to the granule separator.

In the opening / closing device 10 of the present embodiment, the driving force for driving the opening / closing valve 11 to the closed state is smaller than the driving force for driving the opening / closing valve 11 to the opened state. When driving 11 to the closed state, when the resin pellet P is about to be caught between the valve body 11a and the inner surface of the pipe 3, the on-off valve 11 can be stopped before the closed limit position. Therefore, it is possible to prevent the resin pellet P from being caught between the valve body 11a and the inner surface of the pipe 3, and it is possible to prevent malfunction of the on-off valve 11 due to the biting of the resin pellet P.
Further, since the driving force for driving the on-off valve 11 to the open state is large, the on-off valve 11 can be reliably driven to the open-side limit position with the resin pellet P in the pipe 3. Therefore, the flow passage area of the resin pellet P can be secured wider than when the on-off valve 11 is stopped at the opening limit position, and the flow of the resin pellet P can be prevented from deteriorating.

  Moreover, in the opening / closing apparatus 10 of this embodiment, since the on-off valve 11 is comprised by the butterfly valve rotated within the piping 3, compared with the case where the on-off valve is comprised by the slide valve which moves to a linear direction. Thus, the shape of the pipe 3 can be simplified.

  Further, in the opening / closing device 10 of the present embodiment, compressed air is supplied from one compressor 31 to the first pressure chamber 21a and the second pressure chamber 21b, so that a pressure supply source is provided for each of the pressure chambers 21a and 21b. Cost.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

  For example, in the above embodiment, the closing limit position of the on-off valve 11 is a position inclined by an angle θ of less than 90 degrees with respect to the pipe axis direction of the pipe 3, but the closing limit position is the pipe of the pipe 3. It may be a position orthogonal to the axial direction.

  In the above embodiment, the rotary actuator 20 is operated by air pressure, but a rotary actuator operated by oil pressure may be used. In this case, a hydraulic pump or the like is used instead of the compressor 31 as a pressure supply source. In addition, when hydraulic fluid is supplied to one of the two pressure chambers of the rotary actuator, the hydraulic fluid discharged from the other pressure chamber is returned to the hydraulic pump for circulation.

Moreover, in the said embodiment, although the on-off valve 11 is comprised by the butterfly valve which can rotate within the piping 3, an on-off valve is not limited to this. For example, like the opening / closing device 110 shown in FIG. 7, the opening / closing valve 111 may be configured by a slide valve that can move in a direction orthogonal to the pipe axis direction of the pipe 103. The on-off valve 111 is driven by a cylinder (direct acting actuator) 120. Two pressure chambers 121a and 121b partitioned by a piston 123 are formed inside the cylinder 120. The first pressure chamber 121a communicates with the first flow path 34, and the second pressure chamber 121b is a second flow chamber. It communicates with the road 35. When compressed air is supplied to the first pressure chamber 121a as shown in FIG. 7 (a), the on-off valve 111 is opened, and as shown in FIG. 7 (b), compressed air is supplied to the second pressure chamber 121b. Is supplied, the on-off valve 111 is closed. In addition, a groove 103a is formed on the inner surface of the pipe 103 to support the distal end of the opening / closing valve 111 in the extending direction when the opening / closing valve 111 is in a closed state.
In this modified example, when the pressure of the compressed air supplied to the second pressure chamber 121b is smaller than the pressure of the compressed air supplied to the first pressure chamber 121a, the on-off valve 111 is driven in the closed state. Since the on / off valve 111 can stop before the closing limit position of the movable range when the resin pellet is about to be caught between the upper or lower surface of the on / off valve 111 and the inner surface of the groove 103a, the resin pellet P biting can be prevented. Further, when the on-off valve 111 is driven to the open state, it can be surely moved to the open-side limit position, so that it is possible to prevent the flow path area from becoming narrow.

  In the above embodiment, compressed air is supplied from one compressor 31 to the two pressure chambers 21a and 21b. However, a pressure supply source may be provided for each of the pressure chambers 21a and 21b.

  In the above embodiment, the opening / closing device 10 is a part of the transport device 2 that sucks and transports the resin pellets P from the drying hopper 1 by a predetermined amount, and is between the discharge port 1 b of the drying hopper 1 and the bent pipe 4. However, the application target of the switchgear according to the present invention is not limited to this. The opening / closing device of the present invention includes an opening / closing valve disposed in a pipe through which a granular material (may be other than a resin pellet) flows, and the opening / closing valve is opened from a state in which the granular material is present in the pipe. The present invention can be applied to an opening / closing device that switches to a closed state. That is, the opening / closing device of the present invention may be applied to a suction pneumatic transportation device having a configuration other than the transportation device 2 of the above embodiment, or may be applied to devices other than the suction pneumatic transportation device.

3, 103 Piping 10, 110 Open / close device 11, 111 Open / close valve 11a Valve body 11b Valve shaft 20 Rotary actuator 21a First pressure chamber 21b Second pressure chamber 30 Air supply section (fluid supply section)
31 Compressor (fluid supply source)
32 Air supply path (fluid supply path)
33 Switching valve 34 First flow path 35 Second flow path 36 Pressure reducing valve 120 Cylinder 121a First pressure chamber 121b Second pressure chamber

Claims (3)

An on-off valve that is arranged inside a pipe to which the powder is supplied and is movable between an open state that allows passage of the powder and a closed state that blocks passage of the powder,
A fluid pressure actuator having two pressure chambers therein, and driving the on-off valve by the pressure of fluid supplied to the pressure chambers;
A fluid supply section for supplying fluid to the two pressure chambers,
The fluid pressure actuator drives the open / close valve to the open state when fluid is supplied to a first pressure chamber of the two pressure chambers, and opens and closes when fluid is supplied to a second pressure chamber. to drive the valve in the closed state, when the pressure of the fluid supplied to the second pressure chamber is less than the pressure of the fluid supplied to the first pressure chamber, driving the on-off valve in the closed state A driving force to be smaller than a driving force to drive the on-off valve to the open state,
The fluid supply unit supplies the second pressure chamber with a fluid having a pressure smaller than the pressure of the fluid supplied to the first pressure chamber . The on-off valve is a butterfly valve that is rotatable between the open state and the closed state;
The fluid pressure actuator includes a cylindrical body closed at both ends, a shaft that penetrates the internal space of the body and is connected to a valve shaft of the butterfly valve, and the first pressure chamber fixed to the shaft. The opening / closing device according to claim 1, wherein the opening / closing device comprises a rotary actuator comprising a vane that partitions the first pressure chamber and the vane . The fluid supply unit is
A fluid supply path connected to a fluid supply source;
A first flow path connected to the first pressure chamber;
A second flow path connected to the second pressure chamber;
A switching valve capable of switching between a state in which the fluid supply path is communicated with the first flow path and a state in which the fluid supply path is communicated with the second flow path;
3. The switchgear according to claim 1, further comprising a pressure reducing valve that is disposed in the middle of the second flow path and depressurizes the pressure of the fluid that has flowed into the second flow path from the fluid supply path. .

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