Fluid control device and fluid control method

Abstract

The present invention provides a fluid control device and a fluid control method that, even if the valve body opening / closing device is submerged in water, prevents damage to the valve body opening / closing device by avoiding the ingress of seawater into the protective member, thereby enabling the continued use of the valve body opening / closing device. [Solution] The valve body opening / closing device 10, which serves as a fluid control device, comprises a valve stem 2, a protective member 6a for the valve stem 2, and an air cylinder 30, with the protective member 6a and the air cylinder 30 being connected. When the valve stem 2 rises axially to open the valve body, the piston 33 inside the air cylinder 30 descends to mitigate an excessive increase in the internal pressure of the protective member 6a, and when the valve stem 2 descends axially to close the valve body, the piston 33 inside the air cylinder 30 rises to mitigate an excessive decrease in the internal pressure of the protective member 6a.

Description

[Technical Field]

[0001] The present invention relates to a fluid control device and a fluid control method. [Background technology]

[0002] Conventionally, fluid control devices that control fluid movement by opening and closing valve bodies have been known, such as valve body opening and closing devices that open and close valves installed in water and sewage treatment facilities (see, for example, Patent Documents 1 and 2). Figure 8 is a diagram used to explain a conventional valve body opening and closing device, where Figure 8(a) is a front view of the valve body opening and closing device and Figure 8(b) is a side view of the valve body opening and closing device.

[0003] The valve body opening / closing device 80 in Figure 8 is an external-threaded device in which the threaded portion of the valve stem 2 is located on the outside of the valve, and comprises an operating unit (not shown), a valve stem 2, an electric motor 3, a reduction gear 4, a support base 5, a protective member 6, a handle 7, and a switch housing 8. The operating unit has an "open" button to move the valve body in the fully open direction, a "close" button to move the valve body in the fully closed direction, and a "stop" button to stop the movement of the valve body, and is connected to the electric motor 3. The valve stem 2 is a threaded rod that moves up and down in the axial direction by the rotation of its internal thread, passes through the support base 5, and its lower end is connected to the valve body (not shown). The valve stem 2 is also rotatably held by a bearing 5a at the bottom of the support base 5 and is held by the reduction gear 4 so that its upper part can protrude above the reduction gear 4. The reduction gear 4 is fixed to the support base 5, for example by bolts (not shown), and transmits the rotational force (driving force) supplied from the electric motor 3 to the axial movement of the valve stem 2.

[0004] The protective member 6 is a cylindrical member having a cover 6c at its upper end, protecting the valve stem 2 protruding from the reduction gear 4, and preventing the valve stem 2 from becoming contaminated or rusting. The handle 7 is used to manually open and close the valve body. The switch housing 8 houses a limit switch that automatically stops the valve at a predetermined position (fully open, fully closed, or fully open), a torque switch that automatically stops the valve when abnormal torque is applied to the valve stem, and an interlock switch that stops the rotation of the motor when the handle is in manual position.

[0005] Figure 9 is a diagram used to explain the structure of the reduction gear included in the valve body opening and closing device shown in Figure 8. In Figure 9, the reduction gear 4 comprises an electric gear 14, a worm shaft 16, a worm (screw gear) 17, a worm wheel (helical gear) 18, a sleeve 19, and a stem bush (not shown) fitted inside the sleeve 19. The valve stem (not shown) passes through the worm wheel 18, the sleeve 19, and the stem bush (not shown). The rotating shaft of the electric motor 3 is connected to the electric gear 14 of the reduction gear 4, and the handle 7 is configured to connect to the handle clutch 15 when manually opening and closing the valve body. The worm shaft 16 is positioned between the electric gear 14 and the handle clutch 15, and the electric gear 14 and the handle clutch 15 are fixed to both ends of the worm shaft 16.

[0006] When the electric motor 3 is started by instruction from the control unit, rotational force is supplied from the rotating shaft of the electric motor 3 to the electric gear 14 of the reduction gear 4, and the rotational force is reduced by the two electric gears 14. The reduced rotational force is transmitted to the worm (screw gear) 17 fixed to the worm shaft 16 and the worm wheel (helical gear) 18 that meshes with it, and then to the sleeve 19. When the sleeve 19 rotates, the stem bush (female thread) fitted inside the sleeve 19 rotates, and the valve stem (male thread) connected to mesh with the stem bush moves up and down in the axial direction. As a result, the valve body (not shown) connected to the valve stem also moves up and down, and the valve body opens and closes.

[0007] Specifically, when the "Open" button is pressed on the control panel, the rotational force supplied from the electric motor 3 is transmitted to the valve stem, causing it to rise axially, and the valve body connected to the valve stem opens (Figure 8). Conversely, when the "Close" button is pressed on the control panel, the rotational force supplied from the electric motor is transmitted to the valve stem, causing it to descend axially, and the valve body closes (Figure 8).

[0008] In such conventional valve body opening and closing devices 80, a change in pressure occurs inside the protective member 6 that protects the valve stem 2 as the valve stem 2 moves axially. Specifically, when the "open" button is pressed on the operating unit, the valve stem 2 rises axially, increasing the internal pressure of the protective member 6. At this time, if the protective member 6 is sealed, the internal pressure may increase excessively, potentially damaging the protective member 6, and especially at high heads, the protective member 6 may rupture. Also, when the "close" button is pressed on the operating unit, the valve stem 2 descends axially, decreasing the internal pressure of the protective member 6. At this time, if the protective member 6 is sealed, the internal pressure may decrease excessively, potentially causing the seal material at the mating surface between the reduction gear 4 and the protective member 6 to shift, the protective member 6 to deform, or the operating torque to increase. Therefore, to mitigate such excessive changes in the internal pressure of the protective member 6, conventional valve body opening and closing devices 80 are provided with intake and exhaust holes in the protective member 6. For example, multiple intake and exhaust grooves are provided in the cover 6c at the upper end of the protective member 6 (Figure 8). [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Utility Model Publication No. 58-176121 [Patent Document 2] Japanese Utility Model Publication No. 64-37535 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] Incidentally, in the event of a disaster such as a tsunami, the tsunami may reach the valve opening / closing device before the operation to open or close the valve is completed, potentially submerging the valve opening / closing device. To address such situations, there are also submersible valve opening / closing devices that will not be damaged even if submerged. However, in conventional external-threaded valve body opening and closing devices widely used in sewage treatment plants, the protective member that protects the valve stem has intake and exhaust holes. Therefore, if the protective member is submerged in seawater, seawater can seep in through the intake and exhaust holes, causing rust on the valve stem and rendering the valve body opening and closing device unusable. In other words, conventional valve body opening and closing devices have the problem of being damaged when submerged because it is difficult to waterproof the valve stem.

[0011] The object of the present invention is to provide a fluid control device and a fluid control method that, even when the valve body opening and closing device is submerged in water, prevents damage to the valve body opening and closing device by avoiding the ingress of seawater into the protective member, and allows the valve body opening and closing device to be used continuously. [Means for solving the problem]

[0012] To achieve the above objective, the fluid control device of the present invention is a fluid control device that controls the movement of a fluid by opening and closing a valve body, comprising: an operating unit for operating the opening and closing of the valve body; a valve stem connected to the valve body and opening and closing the valve body by axial movement; a reduction gear connected to the valve stem and transmitting a driving force supplied from an electric motor to the axial movement of the valve stem; and a protective member that protects the valve stem protruding above the reduction gear, and further comprising an internal pressure adjustment means connected to the protective member and adjusting the internal pressure of the protective member in accordance with the axial movement of the valve stem.

[0013] To achieve the above objective, the present invention provides a fluid control method for controlling the movement of a fluid by opening and closing a valve body, comprising: an operating unit for operating the opening and closing of the valve body; a valve stem connected to the valve body and opening and closing the valve body by axial movement; a reduction gear connected to the valve stem and transmitting a driving force supplied from an electric motor to the axial movement of the valve stem; and a protective member that protects the valve stem protruding above the reduction gear, wherein the fluid control method uses a fluid control device having an internal pressure adjustment means connected to the protective member and adjusting the internal pressure of the protective member according to the axial movement of the valve stem, characterized in that when the valve stem rises in the axial direction, the internal volume of the protective member and the internal pressure adjustment means increases; and when the valve stem descends in the axial direction, the internal volume of the protective member and the internal pressure adjustment means decreases. [Effects of the Invention]

[0014] According to the present invention, even if the valve body opening and closing device is submerged in water, seawater can be prevented from entering the protective member, thereby preventing damage to the valve body opening and closing device and allowing the valve body opening and closing device to continue to be used. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1(a) is a front view of the valve body opening / closing device as a fluid control device according to the first embodiment of the present invention, and Figure 1(b) is a side view of the valve body opening / closing device. [Figure 2] Figure 1 is used to explain the operation of the valve opening and closing mechanism in which the valve body is opened and closed. [Figure 3] These diagrams are used to illustrate the air cylinder included in the valve opening and closing device of Figure 1. Figure 3(a) is a side view of the air cylinder, and Figure 3(b) is a cross-sectional view along line AA in Figure 3(a). [Figure 4] This flowchart shows the procedure for the fluid control process performed by the valve opening / closing device shown in Figure 1. [Figure 5]This is a diagram schematically showing a valve element opening / closing device as a fluid control device according to the second embodiment of the present invention, where FIG. 5(a) is a front view showing the positional relationship between the protection member and the telescopic member when the upper end portion of the valve stem is at the fully closed position of the valve element (the fully closed position of the valve stem), and FIG. 5(b) is a front view showing the positional relationship between the protection member and the telescopic member when the upper end portion of the valve stem is at the fully open position of the valve element (the fully open position of the valve stem). [Figure 6] This is a diagram used for explaining the protection member and the telescopic member provided in the valve element opening / closing device of FIG. 5, where FIG. 6(a) is a cross-sectional view of the protection member and the telescopic member, FIG. 6(b) is a cross-sectional view of the protection member taken along line B-B of FIG. 6(a), and FIG. 6(c) is a top view of the telescopic member of FIG. 6(a). [Figure 7] This is a flowchart showing the procedure of fluid control processing executed by the valve element opening / closing device of FIG. 5. [Figure 8] This is a diagram used for explaining a conventional valve element opening / closing device, where FIG. 8(a) is a front view of the valve element opening / closing device, and FIG. 8(b) is a side view of the valve element opening / closing device. [Figure 9] This is a diagram used for explaining the structure of the speed reducer provided in the valve element opening / closing devices of FIG. 1, FIG. 5 and FIG. 8. MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0017] FIG. 1 is a diagram schematically showing a valve element opening / closing device as a fluid control device according to the first embodiment of the present invention, where FIG. 1(a) is a front view of the valve element opening / closing device, and FIG. 1(b) is a side view of the valve element opening / closing device. In the valve element opening / closing device 10 of FIG. 1, members having the same structures and functions as the members used in the valve element opening / closing device 80 of FIG. 8 are denoted by the same reference numerals as those used in FIG. 8.

[0018] The valve body opening / closing device 10 in Figure 1 is an external-threaded device in which the threaded portion of the valve stem 2 is located on the outside of the valve. It comprises an operating unit (not shown), a valve stem 2, an electric motor 3, a gearbox 4, a support base 5, a protective member 6a, a handle 7, a switch housing 8, and an air cylinder 30 (internal pressure adjustment means). The operating unit has an "open" button to move the valve body in the fully open direction, a "close" button to move the valve body in the fully closed direction, and a "stop" button to stop the movement of the valve body, and is connected to the electric motor 3. The valve stem 2 is a threaded rod that moves up and down axially by the rotation of its internal thread, passes through the support base 5, and its lower end is connected to the valve body (not shown). The valve stem 2 is rotatably held by a bearing 5a at the bottom of the support base 5 and is held by the gearbox 4 so that its upper part can protrude above the gearbox 4. The gearbox 4 is fixed to the support base 5, for example by bolts (not shown), and transmits the rotational force supplied from the electric motor 3 to the axial movement of the valve stem 2.

[0019] The protective member 6a is a cylindrical member with a closed upper end and has intake and exhaust holes 11 on its upper side surface, protecting the valve stem 2 protruding from the reduction gear 4 and preventing the valve stem 2 from becoming contaminated or rusting. The air cylinder 30 is fixed to the protective member 6a by fittings 12 such as brackets, and has a head-side port 32a on its upper side surface and a piston 33 inside. The intake and exhaust holes 11 of the protective member 6a and the head-side port 32a of the air cylinder 30 are connected by a connecting pipe 13 such as a pipe or hose, and are configured to allow air to move between the inside of the protective member 6a and the inside of the air cylinder 30.

[0020] Handle 7 is used to manually open and close the valve body. By pushing or pulling handle 7 axially, it is possible to switch from manual to electric operation, or from electric to manual operation. The switch housing 8 houses a limit switch that automatically stops the valve at a predetermined position (fully open, fully closed, or fully open), a torque switch that automatically stops the valve when abnormal torque is applied to the valve stem, and an interlock switch that stops the rotation of the electric motor when the handle is in manual mode. The opening meter 1 displays the open / closed state of the valve body in conjunction with the limit switch.

[0021] Figure 9 is used to explain the structure of the reduction gear included in the valve body opening / closing device of Figure 1, and is the same figure used to explain the structure of the reduction gear included in the valve body opening / closing device of Figure 8.

[0022] In Figure 9, the reduction gear 4 comprises an electric gear 14, a worm shaft 16, a worm (screw gear) 17, a worm wheel (helical gear) 18, a sleeve 19, and a stem bush (not shown) fitted inside the sleeve 19. The valve stem (not shown) passes through the worm wheel 18, sleeve 19, and stem bush (not shown). The rotating shaft of the electric motor 3 is connected to the electric gear 14 of the reduction gear 4, and the handle 7 is configured to connect to the handle clutch 15 when the valve body is opened and closed manually. The worm shaft 16 is positioned between the electric gear 14 and the handle clutch 15, and the electric gear 14 and the handle clutch 15 are fixed to both ends of the worm shaft 16. The aforementioned limit switch housed in the switch housing 8 is operated via the rotation of the worm shaft 16. Also, when the valve body is opened and closed manually, the rotation of the handle 7 is transmitted to the worm shaft 16 via the handle clutch 15.

[0023] When the electric motor 3 is started by instruction from the control unit, rotational force is supplied from the rotating shaft of the electric motor 3 to the electric gear 14 of the reduction gear 4, and the rotational force is reduced by the two electric gears 14. The reduced rotational force is transmitted to the worm (screw gear) 17 fixed to the worm shaft 16 and the worm wheel (helical gear) 18 that meshes with it, and then to the sleeve 19. When the sleeve 19 rotates, the stem bush (female thread) fitted inside the sleeve 19 rotates, and the valve stem (male thread) connected to mesh with the stem bush moves up and down in the axial direction. As a result, the valve body (not shown) connected to the valve stem also moves up and down, and the valve body opens and closes.

[0024] Figure 2 is a diagram used to explain the operation of the valve opening and closing device shown in Figure 1 in which the valve body is opened and closed.

[0025] In Figure 2, the valve stem 2 of the valve body opening / closing device 10 extends downward from the support base 5. The valve body 21, which controls the flow of fluid, is housed inside the valve casing 22, and the valve stem 2 is connected to the valve body 21 via a connecting rod 23. As the valve body 21, for example, a gate valve that moves a disc-shaped valve body in a direction approximately perpendicular to the direction of fluid flow, or a water control door (gate) that moves a rectangular door in a direction approximately perpendicular to the direction of fluid flow can be used.

[0026] When the "Open" button is pressed on the control panel, the rotational force supplied from the electric motor 3 is transmitted by the reduction gear 4 to cause the valve stem 2 to rise axially, and consequently the valve body 21 connected to the valve stem 2 via the connecting rod 23 rises. When the upper end of the valve stem 2 reaches the fully open position of the valve body (hereinafter referred to as the "valve stem fully open position"), the valve body 21 is completely open. When the "Close" button is pressed on the control panel, the rotational force supplied from the electric motor 3 is transmitted to cause the valve stem 2 to descend axially, and consequently the valve body 21 connected to the valve stem 2 descends. When the upper end of the valve stem 2 descends to the fully closed position of the valve body (hereinafter referred to as the "valve stem fully closed position"), the valve body 21 is completely closed. Furthermore, a mechanism is installed to transmit the opening degree to a remote control room, allowing the opening degree of the valve body to be controlled from a remote control room.

[0027] Figure 3 is used to illustrate the air cylinder of the valve opening / closing device shown in Figure 1. Figure 3(a) is a side view of the air cylinder, and Figure 3(b) is a cross-sectional view along line AA in Figure 3(a).

[0028] The air cylinder 30 (internal pressure adjustment means) in Figure 3 comprises a cylinder tube 31, a piston 33, a piston rod 34, and a rod cover 36. Inside the cylinder tube 31, the piston 33, fixed to the piston rod 34, is housed in a state where it can slide against the inner wall of the cylinder tube 31. A piston packing 35 is placed between the cylinder tube 31 and the piston 33, sealing the space between the piston 33 and the inner wall of the cylinder tube 31. Inside the cylinder tube 31, the piston rod 34 is held in a slidable state by the rod cover 36. A rod packing (not shown) is placed between the piston rod 34 and the rod cover 36, sealing the space between the piston rod 34 and the rod cover 36 and preventing dust from entering the cylinder tube 31 from the outside. The cylinder tube 31 has a head-side port 32a and a rod-side port 32b, and each port is fitted with a tapered pipe thread. The head-side port 32a is connected to the intake / exhaust port 11 of the protective member 6a via the connecting pipe 13 (Figure 1), and the rod-side port 32b is fitted with an insect screen and opened to the atmosphere.

[0029] Returning to Figure 1, when the "Open" button is pressed on the control panel, the valve stem 2 slowly rises. The space in which the valve stem 2 is housed is sealed by the protective member 6a and the air cylinder 30. Because there is a load from the piston 33 inside the air cylinder 30, as the valve stem 2 rises, the volume of air inside the protective member 6a and the air cylinder 30 decreases, and the pressure of the air inside gradually increases. At this time, the piston 33 inside the air cylinder 30 descends to mitigate the excessive increase in air pressure, and the volume inside the protective member 6a and the air cylinder 30 increases. Consequently, air inside the protective member 6a flows into the air cylinder 30, increasing the volume of air inside the protective member 6a and the air cylinder 30 while simultaneously decreasing the pressure of the air inside. As a result, it is possible to prevent the protective member 6a from being damaged due to an excessive increase in pressure. After that, when the upper end of the valve stem 2 reaches the fully open position, the valve body 21 is completely opened, and the air pressure in the space in which the valve stem 2 is located no longer increases, so the descent of the piston 33 stops.

[0030] Next, when the "close" button is pressed on the control unit 1, the valve stem 2 slowly descends. The space in which the valve stem 2 is housed is sealed by the protective member 6a and the air cylinder 30. As the valve stem 2 descends, the volume of air inside the protective member 6a and the air cylinder 30 increases, and the pressure of the air inside gradually decreases. When the pressure of the air inside becomes a negative pressure that overcomes the load from the piston 33 inside the air cylinder 30, the piston 33 inside the air cylinder 30 rises. As a result, the internal volume of the protective member 6a and the air cylinder 30 decreases, and the excessive decrease in the internal air pressure is mitigated. Consequently, air inside the air cylinder 30 flows into the protective member 6a, and as the volume of air inside the protective member 6a and the air cylinder 30 decreases, the internal air pressure increases. As a result, it is possible to prevent the seal material at the mating surface between the reduction gear 4 and the protective member 6a from shifting, the protective member 6a from deforming, and the operating torque from increasing due to an excessive decrease in pressure. Subsequently, when the upper end of the valve stem 2 reaches the fully closed position, the valve body 21 is completely closed, and the air pressure in the space where the valve stem 2 exists does not decrease any further, so the upward movement of the piston 33 stops.

[0031] In this way, the air cylinder 30 can adjust the internal pressure in accordance with the axial movement of the valve stem 2 so as not to generate excessively high or low pressure inside the protective member 6a, thereby preventing damage or deformation of the protective member 6a.

[0032] The dimensions and operating conditions of the air cylinder 30 used in this embodiment are not particularly limited, as long as the internal pressure can be adjusted so that the internal pressure of the protective member 6a does not increase or decrease excessively in accordance with the axial movement of the valve stem 2. For example, if the diameter of the valve stem 2 is 52 to 70 mm and the opening / closing stroke is 700 to 1200 mm, the inner diameter of the cylinder tube 31 constituting the air cylinder 30 is 80 to 100 mm, the cylinder stroke is 400 to 800 mm, and the operating pressure of the cylinder is 0.1 to 0.9 kg / cm². 2 Preferably 0.3 to 0.7 kg / cm³ 2Furthermore, it is preferable to manufacture the air cylinder 30 using a material such as stainless steel that suppresses the occurrence of rust.

[0033] In order for the piston 33 inside the air cylinder 30 to move up and down appropriately so that excessively high or low pressure does not occur inside the protective member 6a, the air cylinder 30 is set, for example, so that the internal air pressure is 0.1 to 0.9 kg / cm². 2 Preferably 0.3 to 0.7 kg / cm³ 2 It is best used under conditions where the theoretical thrust is 24-55 kgf, the effective thrust is 70-95% of the theoretical thrust (estimated value), and the load rate is 1-2 times per day. In addition, the protective member 6a and the air cylinder 30 must be manufactured with the dimensional and machining accuracy specified in the design, and must be inspected and lubricated regularly.

[0034] If the air cylinder 30 is submerged in seawater due to a disaster such as a tsunami, seawater will flow in through the rod-side port 32b, which is open to the atmosphere. In this case, the air cylinder 30 may rust and become unusable, but the other components of the valve body opening / closing device 10 (Figure 1) are sealed and will not be damaged by water ingress. Therefore, even in the event of a disaster such as a tsunami, the valve body opening / closing device 10 can be quickly restored and used continuously by replacing or repairing only the air cylinder 30.

[0035] Figure 4 is a flowchart showing the procedure of the fluid control process performed by the valve opening / closing device in Figure 1.

[0036] The valve body opening / closing device 10 used in the liquid control process shown in Figure 4 has a valve stem 2 with a diameter of 70 mm, an opening / closing stroke of 1000 mm, an inner diameter of the cylinder tube 31 constituting the air cylinder 30 of 100 mm, a cylinder stroke of 650 mm, and an operating pressure of 0.5 kg / cm². 2 That was the case.

[0037] In Figure 4, first, when the "Open" button on the control panel is pressed, the electric motor 3 starts (S41), and rotational force in the "Open" direction is supplied from the electric motor 3 to the reduction gear 4 (Figure 9). Next, the supplied rotational force is transmitted in the reduction gear 4 to the upward movement of the valve stem 2, causing the valve stem 2 to rise (S42). As the valve stem 2 rises, the pressure inside the protective member 6a and the air cylinder 30 increases. At this time, to mitigate the excessive increase in pressure, the piston 33 inside the air cylinder 30 descends, increasing the volume inside the protective member 6a and the air cylinder 30 (S43). This allows the valve stem 2 to rise without excessively high pressure being generated in the internal space. After that, when the upper end of the valve stem 2 reaches the fully open position, the valve body 21 is completely opened (S44).

[0038] Next, when the "close" button on the control panel is pressed, the electric motor 3 starts (S45), and rotational force in the "close" direction is supplied from the electric motor 3 to the reduction gear 4 (Figure 9). Subsequently, the supplied rotational force is transmitted in the reduction gear 4 to the downward movement of the valve stem 2, causing the valve stem 2 to descend (S46). As the valve stem 2 descends, the pressure inside the protective member 6a and the air cylinder 30 decreases. At this time, to mitigate an excessive decrease in pressure, the piston 33 inside the air cylinder 30 rises, and the volume inside the protective member 6a and the air cylinder 30 decreases (S47). As a result, the valve stem 2 can be lowered without excessively low pressure being generated in the internal space. After that, when the valve stem 2 reaches the fully closed position, the valve body 21 is completely closed (S48). This completes the fluid control process. However, if you wish to open the valve body 21 again, you can return to the operation of pressing the "Open" button on the control unit (S41) and then perform the subsequent operations (S42) to (S44) to open the valve body 21 again. By repeating the above operations, you can repeatedly open and close the valve body 21.

[0039] In the liquid control process shown in Figure 4, the air pressure inside the air cylinder 30 is set to 0.5 kg / cm². 2 The theoretical thrust is 39 kgf (0.5 kg / cm²). 2 The dimensions were set to ×π × 10cm × 10cm / 4), with effective thrust approximately 90% of theoretical thrust (estimated value), and a load factor of 1-2 times / day.

[0040] In this way, the air cylinder 30 can adjust its internal pressure to mitigate the changes in internal pressure of the protective member 6a that occur with the axial movement of the valve stem 2, thereby preventing deformation or damage to the protective member 6a due to increases or decreases in pressure.

[0041] Next, a second embodiment of the present invention will be described.

[0042] Figure 5 is a schematic diagram showing a valve body opening and closing device as a fluid control device according to a second embodiment of the present invention. Figure 5(a) is a front view showing the positional relationship between the protective member and the expandable member when the upper end of the valve stem is in the fully closed position, and Figure 5(b) is a front view showing the positional relationship between the protective member and the expandable member when the upper end of the valve stem is in the fully open position.

[0043] The valve body opening / closing device 50 in Figure 5 has basically the same configuration and function as the valve body opening / closing device 10 in Figure 1, except that instead of using a protective member 6a with a closed upper end and an air cylinder 30, it uses a protective member 6b with an open upper end and has an expandable / contractable member 60 placed on top of it.

[0044] The valve body opening / closing device 50 in Figure 5 comprises an operating unit (not shown), a valve stem 2, an electric motor 3 (not shown), a reduction gear 4, a support base 5, a protective member 6b, a handle 7, a switch housing 8, and an extendable member 60. The structure and function of the operating unit, valve stem 2, electric motor 3, reduction gear 4, support base 5, handle 7, and switch housing 8 in Figure 5 are the same as those of the valve body opening / closing device 10 (first embodiment) in Figure 1, so the protective member 6b and the extendable member 60 will be described below.

[0045] In Figure 5, the protective member 6b is a cylindrical member with an open upper end, and an expandable member 60 is attached to the upper part of the protective member 6b. The expandable member 60 consists of a cylindrical side portion 60a having an inner diameter larger than the outer diameter of the protective member 6b, and a top portion 60b that covers the upper end of the side portion 60a. The space in which the valve stem 2 exists is sealed by the protective member 6b and the expandable member 60, and as the valve stem 2 moves in the axial direction, the expandable member 60 moves vertically on the outside of the upper part of the protective member 6b. In other words, the expandable member 60 has the function of expanding or contracting the length of the side surface of the cylindrical member that forms the space in which the valve stem 2 exists (the total length of the side surface formed by the protective member 6b and the expandable member 60).

[0046] Figure 6 is used to illustrate the protective member and expandable member provided in the valve opening and closing device of Figure 5. Figure 6(a) is a cross-sectional view of the protective member and expandable member, Figure 6(b) is a cross-sectional view of the protective member along line BB in Figure 6(a), and Figure 6(c) is a top view of the expandable member in Figure 6(a).

[0047] In Figures 6(a) and 6(b), the protective member 6b has an open upper end, and four stoppers 66 are fixed to the side surface near the upper end of the protective member 6b by socket head cap screws 65. On the other hand, the expandable member 60 has an open lower end, and a flange 60c is formed at the lower end of the expandable member 60. An O-ring case 61, positioned to contact the outer circumference of the protective member 6b, is fixed to the flange 60c of the expandable member 60 by bolts 62 (8 pieces) and nuts 63 (8 pieces). As a result, the expandable member 60 and the O-ring case move together in the vertical direction on the outside of the protective member 6b. A packing (O-ring) 64 is fitted to the inner surface of the O-ring case 61 that contacts the outer circumference of the protective member 6b, sealing the space between the protective member 6b and the expandable member 60. As the expandable member 60 rises, the O-ring case 61 comes into contact with the stoppers 66, so the stoppers 66 have the function of holding the expandable member 60 so that it does not come off the protective member 6b. Furthermore, the stopper 66 also functions as a guide when the telescopic member 60 moves in the vertical direction. The lower end of the protective member 6b is fixed by a flange 67 and connected to the reduction gear 4.

[0048] The dimensions of the protective member 6b and the expandable member 60 depend on the diameter of the valve stem and the length of the opening and closing stroke. For example, in the case of a gate (valve body) with a valve stem diameter of 52 to 70 mm and an opening and closing stroke of 700 to 1200 mm, the outer diameter of the protective member 6b is 80 to 130 mm, the inner diameter of the expandable member 60 is 100 to 150 mm, and the difference between the inner diameter of the expandable member 60 and the outer diameter of the protective member 6b is 15 to 35 mm, preferably 20 to 30 mm. The longitudinal length of the protective member 6b is usually 800 to 1300 mm, and the longitudinal length of the expandable member 60 is usually 360 to 700 mm. Furthermore, the longitudinal length of the expandable member 60 can be designed to be 1 / 3 to 2 / 3 of the longitudinal length of the protective member 6b. The height to which the expandable member 60 rises when the upper end of the valve stem 2 moves from the fully closed position to the fully open position is typically 16 to 33 cm.

[0049] For the expansion member 60 to move appropriately up and down outside the protective member 6b in response to the axial movement of the valve stem 2, the expansion member 60 and the protective member 6b must be manufactured with the dimensional and machining accuracy specified in the design. The air pressure required to raise the expansion member 60 varies depending on the gate size, but is typically 0.025 to 0.052 kg / cm². 2 It is extremely small. Furthermore, it needs to be made from rust-resistant materials such as stainless steel, and requires regular inspection and lubrication.

[0050] Returning to Figure 5, when the upper end of the valve stem 2 is in the fully closed position shown in Figure 5(a), the valve body 21 is completely closed. At this time, the top portion 60b of the expandable member 60 is in contact with the upper end (open) of the protective member 6b, and the entire side portion 60a of the expandable member 60 overlaps with the protective member 6b (Figure 5(a)).

[0051] First, when the "Open" button is pressed on the control panel, the valve stem 2 slowly rises. The space in which the valve stem 2 is housed is sealed by the protective member 6b and the expandable member 60. Due to the weight of the expandable member 60 and the friction of the O-ring case 61, as the valve stem 2 rises, the volume of air inside the protective member 6b and the expandable member 60 decreases, and the air pressure gradually increases. At this time, the expandable member 60 rises to mitigate the excessive increase in air pressure, increasing the internal volume of the protective member 6b and the expandable member 60. Consequently, the volume of air inside increases, preventing excessively high pressure from being generated in the internal space and preventing damage to the protective member 6b. Subsequently, when the upper end of the valve stem 2 reaches the fully open position shown in Figure 5(b), the valve body 21 is completely opened, and the air pressure in the space in which the valve stem 2 resides no longer increases, so the rise of the expandable member 60 stops.

[0052] Furthermore, if the expandable member 60 continues to rise, the O-ring case 61 fixed to the lower end of the expandable member 60 will come into contact with the stopper 66 fixed near the upper end of the protective member 6b (Figure 6). Therefore, the longitudinal length of the expandable member 60 must be such that the O-ring case 61 at the lower end of the expandable member 60 does not come into contact with the stopper 66 near the upper end of the protective member 6b before the valve stem 2 reaches the fully open position.

[0053] Next, when the "close" button is pressed on the control panel, the valve stem 2 slowly descends. The space in which the valve stem 2 is housed is sealed by the protective member 6b and the expandable member 60. Due to the weight of the expandable member 60 and the friction load of the O-ring case 61, the expandable member 60 immediately descends as the valve stem 2 descends, reducing the internal volume of the protective member 6b and the expandable member 60. As a result, the volume and pressure of the air inside the protective member 6b and the expandable member 60 do not change significantly. Consequently, it is possible to prevent excessive pressure reduction from causing the sealing material at the mating surface between the reduction gear 4 and the protective member 6b to shift, the protective member 6b to deform, or an increase in operating torque. Subsequently, when the upper end of the valve stem 2 reaches the fully closed position shown in Figure 5(a), the valve body 21 is completely closed, the top 60b of the expandable member 60 contacts the upper end of the protective member 6b, and the descent of the expandable member 60 stops.

[0054] Figure 7 is a flowchart showing the procedure of the fluid control process performed by the valve opening / closing device shown in Figure 5.

[0055] The valve body opening and closing device (Figure 5) that performs fluid control processing shown in Figure 7 has a valve stem 2 with a diameter of 70 mm, a protective member 6b with an outer diameter of 112 mm and an axial length of 1100 mm, an expandable member 60 with an inner diameter of 134.2 mm and an axial length of 590 mm, and a difference of 22.2 mm between the inner diameter of the expandable member 60 and the outer diameter of the protective member 6b. The valve body 21 uses a gate with an opening and closing stroke of 1000 mm, and the valve body 21 is in a completely closed state.

[0056] In Figure 7, first, when the "open" button on the operation unit is pressed, the electric motor 3 starts (S71), and rotational force in the "open" direction is supplied from the electric motor 3 to the speed reducer 4 (Figure 9). Next, the supplied rotational force is transmitted in the speed reducer 4 to the upward motion of the valve stem 2, and the valve stem 2 rises in the axial direction (S72). When the valve stem 2 rises, the pressure of the air present inside the protective member 6b and the telescopic member 60 gradually increases. At this time, the telescopic member 60 rises so as to alleviate the excessive increase in air pressure, and the internal volume of the protective member 6b and the telescopic member 60 increases (S73). Thereby, the valve stem 2 can be raised without generating an excessively high pressure in the internal space. After that, when the upper end of the valve stem 2 reaches the fully open position of the valve stem in Figure 5(b), the rise of the valve stem 2 stops, and the valve body 21 is fully opened (Figure 2) (S74). In this fluid control process, the movement distance of the telescopic member 60 when the upper end of the valve stem 2 moves from the fully closed position to the fully open position is 27 cm, and the amount of increase in the internal volume of the protective member 6b and the telescopic member 60, that is, the amount of increase in the volume of the air present inside the protective member 6b and the telescopic member 60 is 3850 cm 3 (Figure 5).

[0057] Next, when the "close" button on the control unit is pressed, the electric motor 3 starts (S75), and rotational force in the "close" direction is supplied from the electric motor 3 to the reduction gear 4 (Figure 9). Subsequently, the supplied rotational force is transmitted in the reduction gear 4 to the downward movement of the valve stem 2, causing the valve stem 2 to descend axially (S76). As the valve stem 2 descends, the air pressure inside the protective member 6b and the expandable member 60 decreases. At this time, because there is a load due to the weight of the expandable member 60, the expandable member 60 immediately descends along with the descent of the valve stem 2, and the internal volume of the protective member 6b and the expandable member 60 decreases (S77). As a result, the valve stem 2 can be lowered without a large change in the volume and pressure of the air inside the space. After that, when the upper end of the valve stem 2 reaches the fully closed position of the valve stem in Figure 5(a), the top of the expandable member 60 contacts the upper end of the protective member 6b, and the valve body 21 is completely closed (S78). This completes the fluid control process. However, if you wish to open the valve body 21 again, you can return to the operation of pressing the "Open" button on the control unit (S71) and then perform the subsequent operations (S72) to (S74) to open the valve body 21 again.

[0058] In this way, the expandable member 60 can adjust its internal pressure to mitigate the pressure changes inside the protective member 6b that occur with the axial movement of the valve stem 2, thereby preventing deformation or damage to the protective member 6b due to increases or decreases in pressure.

[0059] Although embodiments of the present invention have been described above, the present invention is not limited in any way to these embodiments. [Explanation of Symbols]

[0060] 2 valve stems 3. Electric motor 4 Reducer 5 Support stand 6, 6a, 6b Protective members 10 Valve body opening and closing device 30 Air Cylinders 33 pistons 60 Expandable members

Claims

1. A fluid control device that controls the movement of fluid by opening and closing a valve body, An operating unit for operating the opening and closing of the valve body, A valve stem connected to the valve body, which opens and closes the valve body by axial movement, A reduction gear connected to the valve stem, which transmits the driving force supplied from the electric motor to the axial movement of the valve stem, A protective member that protects the valve stem protruding above the reduction gear, Equipped with, A fluid control device characterized by having an internal pressure adjustment means connected to the protective member, which adjusts the internal pressure of the protective member in accordance with the axial movement of the valve stem.

2. The fluid control device according to claim 1, characterized in that the internal pressure adjustment means is an air cylinder.

3. The fluid control device according to claim 1, characterized in that the internal pressure adjustment means is an expandable / contractable member capable of increasing the internal volume of the protective member and the internal pressure adjustment means.

4. The fluid control device according to any one of claims 1 to 3, characterized in that it comprises a support base through which the valve stem passes and which supports the reduction gear.

5. A fluid control device for controlling the movement of a fluid by opening and closing a valve body, comprising: an operating unit for operating the opening and closing of the valve body; a valve stem connected to the valve body and opening and closing the valve body by axial movement; a reduction gear connected to the valve stem and transmitting driving force supplied from an electric motor to the axial movement of the valve stem; and a protective member that protrudes above the reduction gear and protects the valve stem, wherein the fluid control device has an internal pressure adjustment means connected to the protective member and adjusting the internal pressure of the protective member in accordance with the axial movement of the valve stem, When the valve stem rises in the axial direction, a volume increase step occurs in which the internal volume of the protective member and the internal pressure adjusting means increases. When the valve stem descends in the axial direction, a volume reduction step occurs in which the internal volume of the protective member and the internal pressure adjusting means decreases. A fluid control method characterized by having the following features.

6. The fluid control method according to claim 5, characterized in that the internal pressure adjustment means is an air cylinder.

7. The fluid control method according to claim 5, characterized in that the internal pressure adjustment means is an expandable / contractable member capable of increasing the internal volume of the protective member and the internal pressure adjustment means.

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