Valve device

Abstract

[Task] The present invention aims to provide a valve device that is capable of stably controlling the flow rate of a fluid. [Solution] A valve device 1 comprises a valve body 10, which includes a valve port 19 and a first opening section 22, a valve element 64, and a screw conveying unit 80. The screw conveying unit 80 comprises a spindle 81 that rotates about an axis and a second screw conveying element 84 that is displaceable in one direction along an axis L. The second screw conveying element 84 is integral with the valve element 64 and extends from a second flow path 18, in which the valve element 64 is located, across the valve port 19 to a first flow path 17, in which the first opening section 22 is located. A first diaphragm 23 is provided in the second screw conveying element 84, which closes the first opening section 22. The first diaphragm 23 comprises a pressure-bearing surface 23c that faces the valve element 64 and comes into contact with a fluid.The valve element 64 comprises an opposing surface 67, which is opposite the pressure-absorbing surface 23c. The area of ​​the pressure-absorbing surface 23c is larger than the area of ​​the opposing surface 67.

Description

[Technical field]

[0001] The present invention relates to a valve device. [Background technology]

[0002] A valve device for controlling the flow of a fluid is known from the prior art (see, for example, patent document 1). The flow control valve (the valve device) described in patent document 1 comprises, as shown in Fig. As shown in patent document 1, the flow control valve comprises a valve body 12, which includes a primary-side flow path 24 through which a fluid flows, a main valve seat 14, which has a flow path opening connected to the primary-side flow path 24, and a secondary-side flow path 26, which is connected to the flow path opening of the main valve seat 14. The flow control valve further comprises a main valve 30, which moves within the valve body 12 towards or away from the main valve seat 14 to change the degree of opening of the flow path opening, and a pilot valve unit 100, which moves the main valve 30 up and down in the direction of the axis.The main valve 30 comprises a disc-shaped main valve element 34, which is arranged on the side of the primary-side flow path 24, and a fastening means 39, which extends from the center of the main valve element 34 into the flow path opening of the main valve seat 14, extends in the direction of the axis, and is located on the side of the secondary-side flow path 26. A secondary-side diaphragm 50 is attached to the fastening means 39, which is arranged concentrically opposite the main valve 30 and extends orthogonally to the direction of the axis.

[0003] The pilot valve unit 100 comprises a drive shaft 121, which moves along the axis by screw feed, a pilot flow path 72, which is provided in the main valve 30 such that it is opened and closed by the drive shaft 121, and a backpressure chamber 27, which is connected to the pilot flow path 72 and the primary-side flow path 24. When the pilot flow path 72 is opened by screw feed of the drive shaft 121, fluid from the backpressure chamber 27 flows into the pilot flow path 72, causing the pressure in the backpressure chamber 27 to be lower than the pressure in the primary-side flow path 24. This causes the main valve 30 to move upwards along the axis, resulting in the valve opening. As a result, fluid from the primary-side flow path 24, which has a higher pressure, flows towards the secondary-side flow path 26.On the other hand, if the pilot flow path 72 is closed, the pressure in the back pressure chamber 27 is higher than the pressure in the primary-side flow path 24, causing the main valve 30 to move downwards in the direction of the axis, which leads to the valve closing. [Citation list][Patent document]

[0004] [Patent document 1] Patent publication no. JP 6-109163 [Overview of the invention][Technical problem]

[0005] In the flow control valve described above, the surface area of ​​a section of the main valve 30 facing the secondary-side flow path 26 is equal to the surface area of ​​a pressure-absorbing surface of the secondary-side diaphragm 50 opposite the main valve 30. Therefore, when the main valve 30 is installed, the pressure in the secondary-side flow path 26 is exerted directly onto the main valve 30 via the section facing the secondary-side flow path 26 in the direction of the axis upwards, and the pressure in the secondary-side flow path 26 is also exerted downwards via the secondary-side diaphragm 50.This means that an upward force exerted directly on the main valve 30 from the secondary-side flow path 26 and a downward force exerted on the main valve 30 via the secondary-side diaphragm 50 are in equilibrium, and the main valve 30 is not biased in both directions along its axis from the side of the secondary-side flow path 26. Consequently, it is possible to actuate the main valve 30 with a relatively small actuating force.

[0006] However, with this design, when the pressure in the back pressure chamber 27 is reduced during screw feeding of the drive shaft 121 and the opening of the main valve 30, as described above, the main valve 30 is not pre-tensioned in both directions of the axis from the side of the secondary-side flow path 26, which means, for example, that the main valve 30 is slightly lifted in the direction of the axis according to a clearance in the direction of the axis, such as a clearance of a screw of the drive shaft 121, and a valve opening with an unwanted operating dimension of the drive shaft 121 can occur.With this setup, when, for example, a fluid flows from the secondary-side flow path 26 into the primary-side flow path 24, the main valve 30 is pushed upwards in the inflow direction by the fluid flowing from the flow path opening into the primary-side flow path 24 when it closes from a maximum valve opening state. This greatly increases the likelihood of generating hysteresis, which makes closing the main valve 30 more difficult in the direction of axis L according to the aforementioned clearance. Furthermore, the flow rate characteristic, represented by the flow rate of a fluid passing through the flow path opening as a function of an operating parameter of the drive shaft 121, differs between valve opening and valve closing. Consequently, it is difficult to control the flow rate of a fluid in a stable manner.

[0007] The present invention aims to provide a valve device that is capable of stably controlling the flow rate of a fluid. [Means of solving the problem]

[0008] To solve the problem and achieve the purpose, the valve device of the present invention is a valve device comprising a valve body comprising a valve port through which a fluid flows and an opening section opposite the valve port, a valve element which approaches or moves away from the valve port on a side opposite the opening section, a drive section for driving the valve element, and a screw conveyor unit for transmitting a drive force from the drive section to the valve element, characterized in that the screw conveyor unit comprises a first screw conveyor element which rotates about an axis due to the drive force, and a second screw conveyor element which is connected to the first screw conveyor element and is displaceable in one direction of an axis.that the second screw conveying element is integral with the valve element and also extends from a second flow path, in which the valve element is located, via the valve connection to a first flow path, in which the opening section is located; that a sealing element is provided in a section of the second screw conveying element located in the first flow path, which closes the opening section and is also deformable in the direction of the axis; that the sealing element comprises a pressure-bearing surface that is opposite the valve connection and the valve element and comes into contact with the fluid; that the valve element comprises an opposing surface that is opposite the valve connection and the pressure-bearing surface; and that the area of ​​the pressure-bearing surface is greater than the area of ​​the opposing surface.

[0009] According to this present invention, the second screw conveying element and the valve element are integral parts, and the second screw conveying element and the sealing element are also integral parts; therefore, a displacement of the second screw conveying element and the valve element in the direction of the axis is coupled to a deformation of the sealing element in the direction of the axis. Furthermore, in this configuration, the area of ​​the pressure-bearing surface of the sealing element is larger than the area of ​​the opposite surface of the valve element; therefore, the equilibrium between a force exerted on the pressure-bearing surface due to fluid pressure and a force exerted on the opposite surface due to fluid pressure can be disturbed.This results in a greater force with which a fluid biases the valve element towards the side of the valve port (the approach side) via the pressure-bearing surface than a force with which a fluid biases the valve element towards the side opposite the valve port (the distance side) via the opposite surface. This balances the force with which the valve element is to be lifted towards the distance side. Therefore, an opening / closing operation of the valve port can be performed in a state where the valve element is pressed towards the side of the valve port and any play in the axial direction, such as play in the screw conveyor unit, is reduced.Consequently, unwanted lifting of the valve element can be reduced, and unwanted valve opening and the generation of hysteresis can be reduced, so that a valve device can be provided that is able to stably control the flow rate of a fluid.

[0010] It is further preferred that the pressure-receiving surface is formed as a surface that receives a fluid pressure towards an approach side of the direction of the axis, which is a direction in which the valve element approaches the valve port, and that the opposite surface is formed as a surface that receives a fluid pressure towards a distance side of the direction of the axis, which is a direction in which the valve element moves away from the valve port.According to this setup, the pressure-bearing surface that receives a fluid pressure towards the approach side of the axis can be larger than the opposite surface that receives a fluid pressure towards the distance side of the axis, whereby a force with which a fluid biases the valve element towards the side of the valve port via the pressure-bearing surface can be greater than a force with which a fluid biases the valve element towards the side opposite the valve port via the opposite surface.

[0011] Furthermore, it is preferred that a pressure section presses the sealing element against an opening circumferential edge of the opening section, wherein the pressure-receiving surface extends from a section corresponding to an inner edge of the pressure section in the direction of the axis to an outer circumferential surface of the second screw conveying element in a radial direction of the second screw conveying element; the valve element extends in the radial direction of the second screw conveying element; and the opposite surface extends from an outer end section of the valve element in the radial direction to the outer circumferential surface of the second screw conveying element in the radial direction.According to this design, the pressure-bearing area extending from the section corresponding to the inner edge of the pressure section to the outer circumferential surface of the second screw conveying element can be larger than the opposite area extending from the outer end section of the valve element in the radial direction to the outer circumferential surface of the second screw conveying element, whereby a force with which a fluid biases the valve element towards the side of the valve port via the pressure-bearing area can be greater than a force with which a fluid biases the valve element towards the side opposite the valve port via the opposite area.

[0012] Furthermore, it is also possible that when the valve closes, i.e., when the valve port is closed by the valve element, the internal pressure of the first flow path is higher than the internal pressure of the second flow path. According to this setup, when the valve opens, i.e., when the valve port is open, a jet of fluid can be created, bubbling from the first flow path into the second. However, according to this setup, as described above, the valve opening can occur in a state where the valve element is pressed towards the side of the valve port and any play in the direction of the axis, such as the play in the screw conveyor, is reduced. This reduces any unwanted lifting of the valve element corresponding to the aforementioned play in the direction of the axis. This can stabilize the behavior of the valve element immediately before and after the valve opens.

[0013] Furthermore, it is preferred that the area of ​​the pressure-bearing surface is greater than 1.0 times the area of ​​the opposite surface and less than or equal to 4.0 times the area of ​​the opposite surface. According to this design, by making the area of ​​the pressure-bearing surface greater than 1.0 times the area of ​​the opposite surface, the force with which a fluid biases the valve element towards the side of the valve port via the pressure-bearing surface can be greater than the force with which a fluid biases the valve element towards the side opposite the valve port via the opposite surface, thereby suitably reducing the lifting of the valve element.Furthermore, by ensuring that the area of ​​the pressure-bearing surface is less than or equal to 4.0 times the area of ​​the opposite surface, the force with which a fluid biases the valve element towards the valve port via the pressure-bearing surface can be reduced. This, in turn, reduces the excessive increase in the driving force of the actuator section for driving the valve element, thus enabling smooth valve actuation. [Effects of the invention]

[0014] According to the present invention, a valve device can be provided which is able to stably control the flow rate of a fluid. [Brief explanation of the characters] Fig. Figure 1 is a cross-sectional view of a valve device cut along an axis of a spindle according to an embodiment of the present invention; Fig. 2 is a side view of the valve device; Fig. Figure 3 is a perspective view of a first pressure element that forms part of the valve device; Fig. 4(A) is an enlarged cross-sectional view of a first membrane and Fig. 4(B) is an enlarged cross-sectional view of a valve element; Fig. Figure 5 is an enlarged cross-sectional view of area A of Fig. 1; and Fig. Figure 6 is a diagram showing a flow rate characteristic of the valve device. [Forms for carrying out the invention]

[0015] In the following, a valve device 1 according to an embodiment of the present invention is described with reference to Fig. 1 to Fig. The valve device 1 is an electrically actuated valve arranged in a section of a pipeline through which a fluid, such as a liquid or a gas, flows, and is used, for example, to control the flow rate of a fluid. In the following description, a direction along an axis L of a spindle 81 (a first screw conveying element) and a second screw conveying element 84, which are described later, is referred to as the "direction of axis L". One side of the direction of axis L is further referred to as the "top side L1", and the other side is referred to as the "bottom side L2". A direction that intersects the direction of axis L is further referred to as the "crossing direction X". The crossing direction X also corresponds to a radial direction around the axis L. One side of the crossing direction X is further referred to as the "left side X1", and the other side is referred to as the "right side X2".The definition of these directions serves only for better description and these directions do not necessarily correspond to the directions of the valve device 1 in its actual state of use or the like, and the definition does not serve to restrict the respective directions of the valve device 1.

[0016] The valve device 1 comprises, as shown in Fig. Figure 1 shows a valve body 10 comprising a valve port 19 through which a fluid flows, a valve element 64 which moves inside the valve body 10 towards or away from the valve port 19 in the direction of the axis L, and a drive section 70 for driving the valve element 64. The valve device 1 further comprises a screw conveyor 80 for transmitting a drive force from the drive section 70 to the valve element 64. The valve body 10 comprises a tubular body 11 extending in the direction of intersection X. In the end section of the body 11 located on the left side X1, a first port 12 is formed, which is open in the direction of intersection X. An internal thread (not shown) is formed on the inner circumferential surface of the first port 12, and a first articulated tube (not shown), which is screwed to this internal thread, is connected to the first port 12.In the end section of the body 11 located on the right side X2, a second connection 13 is formed, which is open in the direction of intersection X. An internal thread (not shown) is formed on the inner circumferential surface of the second connection 13, and a second articulated tube (not shown), which is screwed to this internal thread, is connected to the second connection 13.

[0017] Inside the body 11, a partition 14 is arranged, extending along an axis α of the body 11. The partition 14 extends inside the body 11 in the direction of intersection X and is supported by a left vertical wall 15, extending from the end section of the partition 14 located in the left side X1 to the inner wall of the body 11 located in the upper surface L1, and by a right vertical wall 16, extending from the end section of the partition 14 located in the right side X2 to the inner wall of the body 11 located in the lower surface L2. With this arrangement, the interior of the body 11 is divided into a first flow path 17, which is connected to the first port 12, and a second flow path 18, which is connected to the second port 13. A first stopper 17a, which projects inwards, is formed on the inner wall of the first flow path 17.A second stopper 18a is formed on the inner wall of the second flow path 18, projecting inwards. The first stopper 17a and the second stopper 18a are, as in . Fig. 2 shown (in Fig. 2 is only the second stopper 18a shown), which is essentially rectangular in side view.

[0018] When connecting the second hinge tube (or the first hinge tube) to the second connection 13 (or the first connection 12) as described above, the first stopper 17a and the second stopper 18a can rest against the front end sections of the respective hinge tubes to limit the degree of tightening. This can prevent the respective hinge tubes from being overtightened. In the middle of the partition 14, as in Fig. Figure 1 shows a valve connection 19, which extends along the axis L and serves to connect the first flow path 17 and the second flow path 18. A valve seat section 20 is formed on the edge section of the valve connection 19 located in the upper surface L1, projecting towards the upper surface L1 over its entire circumference. In cross-sectional view, the upper surface of the valve seat section 20 projects in an arc towards the upper surface L1, and the apex section of the valve seat section 20 forms a contact section 21 that abuts the lower surface of the valve element 64. That is, the contact section 21 is provided in the valve seat section 20, enclosing the valve connection 19 and able to abut the valve element 64.When the valve closes, namely when the valve element 64 rests against the contact section 21 and the valve port 19 is closed, the internal pressure of the first flow path 17 is higher than the internal pressure of the second flow path 18; and when the valve opens, namely when the valve port 19 is open, a fluid flows successively through the first flow path 17, the valve port 19 and the second flow path 18.

[0019] At the position opposite the valve connection 19 on the wall surface of the body 11 located in the underside L2, a substantially circular first opening section 22 (opening section) is formed, extending in the direction of the axis L. A first membrane 23 (a sealing element) is mounted on a lower surface 11a of the wall surface of the body 11 located in the underside L2, closing the first opening section 22. The first membrane 23 is formed in a plate-like shape from a resinous material that is elastically deformable in the direction of the axis L and seals the first opening section 22 to maintain an airtight seal inside the body 11.In the center of the first diaphragm 23, a perforated section 23a is formed, extending through it in the direction of the axis L; and a section of a shaft segment 94 of a valve rod screw 90 (a section of the second screw conveying element 84 located in the first flow path 17) is attached to the perforated section 23a in a state in which the segment is inserted therein in the direction of the axis L. This allows the first diaphragm 23 to be deformed in the direction of the axis L corresponding to a displacement of the valve rod screw 90 and the valve element 64 in the direction of the axis L. A first pressure element 30 is arranged in the underside L2 of the first diaphragm 23.The first pressure element 30 is an element that presses the first membrane 23 towards the lower surface 11a of the body 11 and has the function of maintaining a stable state in which the first membrane 23 is attached to the body 11.

[0020] The first pressure element 30 comprises, as in Fig. Figure 3 shows a substantially rectangular, plate-shaped upper wall section 31. Circular mounting holes 31a are formed at the four corners of the upper surface of the upper wall section 31, extending through one of the plate thickness directions. Stop screws 31b are inserted into the mounting holes 31a (see Figure 3). Fig. 4(A)). Side wall sections 32 are formed at the outer edge of the upper wall section 31, which are curved in an L-shape and extend towards the underside L2. As in Fig. As shown in Figure 4(A), the surfaces of the side wall sections 32, which are directed inwards in the intersection direction X, face a cap 40 described later in the intersection direction X, in order to guide the cap 40 in the direction of the axis L. That is, the side wall sections 32 serve as guides for the cap 40. The design of the side wall sections 32 also makes deformation of the upper wall section 31 in the plate thickness direction less likely. Therefore, the side wall sections 32 also serve as reinforcing sections of the first pressure element 30. With this design, deformation of the upper wall section 31 when the stop screws 31b are tightened is reduced, and deformation of the cap 40 in the direction of the axis L is reduced. In the lower edge sections of the respective side wall sections 32, as shown in Fig. Figure 3 shows projecting sections 32a that extend in an arc towards the underside L2. These projecting sections 32a serve to distinguish a similar element of the first pressure element 30, which is used in a device other than the valve device 1 of the present embodiment, from the first pressure element 30 of the present embodiment.

[0021] The formation of the projecting sections 32a prevents the foreign element from being incorrectly attached, for example, if another component intrudes during the application of the first pressure element 30. A circular opening 33 is formed in the center of the upper wall section 31. A first pressure section 34 (pressure section) is formed at the circumferential edge of the opening 33, which has a predetermined width in the radial direction. The first pressure section 34 extends along the circumferential edge of the first opening section 22 around the axis L (around the axis). The first pressure section 34 projects in an arc towards the upper surface L1, with its central section, which lies radially in a cross-sectional view, being the apex section 35 (shown in Fig. 3 is indicated by a dashed line. As in Fig. As shown in Figure 4(A), the upper surface of the first pressure section 34 rests against the lower surface of the first diaphragm 23 due to the tightening of the stop screws 31b, while the apex section 35 is embedded in the first diaphragm 23. The upper surface of the first pressure section 34 is pressed against the lower surface of the first diaphragm 23 towards the top L1. This presses the first diaphragm 23 against the circumferential edge of the first opening section 22.

[0022] The first membrane 23 is deformable in the direction of the axis L in a section that is located further inward in the radial direction than the inner edge of the first pressure section 34; and the inner edge of the first pressure section 34 defines a deformable region of the first membrane 23. In the present embodiment, this deformable region of the first membrane 23 is specifically referred to as a deformable section 23b, and the surface of the deformable section 23b located in the top surface L1 is referred to as a pressure-bearing surface 23c (see Fig. 4(A)). The pressure-receiving surface 23c is located opposite the valve port 19 and the valve element 64 in the direction of the axis L, may be partially in contact with a fluid, and is formed as a surface that receives a fluid pressure towards the underside L2 (towards the approach side in the direction of the axis L, which is the direction in which the valve element 64 approaches the valve port 19). The pressure-receiving surface 23c may also be formed such that the entire surface is in contact with a fluid. The position of an outer end section 23c1, which is a radially outer end section of the pressure-receiving surface 23c, is equal in the direction of the axis L to the position of the inner edge of the first pressure section 34. That is, the outer end section 23c1 of the pressure-receiving surface 23c is a section that corresponds in the direction of the axis L to the inner edge of the first pressure section 34.

[0023] And the position of an inner end section 23c2, which is a radially inner end section of the pressure-receiving surface 23c, is positioned in the direction of the axis L equal to the position of the outer circumferential surface of a valve rod element 60 (the second screw conveying element 84) described later. That is, the pressure-receiving surface 23c extends from the outer end section 23c1 (from the section which, in the direction of the axis L, corresponds to the inner edge of the first pressure section 34) to the inner end section 23c2 (to the outer circumferential surface of the second screw conveying element 84) in the radial direction of the second screw conveying element 84. In the inner edge section of the first pressure section 34, as in Fig. Figure 3 shows an inclined section 36 extending towards the underside L2 with a reduced diameter. A disc-shaped bottom wall section 37 is formed in the lower end section of the inclined section 36, extending in the direction of intersection X. The formation of the inclined section 36 and the bottom wall section 37 creates a gap in the direction of axis L between the first pressure element 30 and the central section of the first membrane 23, with this gap serving as a deformation clearance for the first membrane 23 towards the underside L2. A hexagonal mounting hole 38 is formed in the center of the bottom wall section 37, extending through it in the direction of axis L.

[0024] As in Fig. As shown in Figure 4(A), a hexagonal columnar hub section 39 is inserted into the mounting hole 38 to be movable in the direction of the axis L. The upper end face of the hub section 39 rests against the lower face of the first membrane 23 to support the first membrane 23 from the underside L2. In the center of the hub section 39, a first through-hole 39a, extending in the direction of the axis L, and a second through-hole 39b, which is connected to the first through-hole 39a, are formed. The first through-hole 39a is open towards the top L1. The second through-hole 39b is fully connected to the first through-hole 39a in the underside L2, is configured to have a larger diameter than the first through-hole 39a, and is open towards the underside L2.At the boundary between the first through-hole 39a and the second through-hole 39b, a stepped section 39c is formed, the diameter of which is increased in the direction of intersection X. The cap 40 for holding the first pressure element 30 is mounted on the underside L2 of the first pressure element 30.

[0025] The cap 40 comprises a flanged section 41 that abuts the lower surface of the first pressure section 34 of the first pressure element 30, an inclined wall section 42 extending from the inner end of the flanged section 41 with its reduced diameter towards the underside L2, and a disc-shaped base plate section 43 extending from the lower end section of the inclined wall section 42 in the intersection direction X. The inclined wall section 42 and the base plate section 43 cover the inclined section 36 and the base wall section 37 of the first pressure element 30. A hole section (not shown) is formed in the flanged section 41, extending in the direction of the axis L, and the stop screw 31b described above is inserted into this hole section.Due to the tightening of the stop screw 31b, the upper surface of the flange section 41 presses the lower surface of the first pressure section 34 towards the top L1. This clamps the first diaphragm 23 between the upper surface of the flange section 41 and the lower surface 11a of the body 11.

[0026] At the position opposite the valve connection 19 of the wall surface of the body 11 located in the upper surface L1, as shown in Fig. As shown in Figure 1, a circular second opening section 24 is formed, extending through it in the direction of the axis L. A second membrane 25 is mounted on an upper surface 11b of the wall surface of the body 11 located in the top L1, and closes the second opening section 24. The second membrane 25 is formed in a plate-like shape with a resinous material that is elastically deformable in the direction of the axis L and seals the second opening section 24 to maintain an airtight seal inside the body 11. A second hole section 25a is formed in the center of the second membrane 25, extending through it in the direction of the axis L; and the valve rod screw 90 is inserted into the second hole section 25a in the direction of the axis L. A second pressure element 50 is arranged in the top L1 of the second membrane 25.The second pressure element 50 is formed in a tubular shape with a base that is open towards the top L1. In a lower plate section 51, which forms the base surface of the second pressure element 50, a projecting section 52 is formed that projects towards the underside L2. In the central section of the second pressure element 50, an inclined surface 53 is formed, which is positioned at an oblique angle towards the center in the direction of the top L1.

[0027] The inclined surface 53 creates a gap in the direction of the axis L between the second pressure element 50 and the central section of the second membrane 25. This gap serves as a deformation clearance for the second membrane 25 relative to the upper surface L1. An insertion hole 54 is formed in the center of the second pressure element 50, extending in the direction of the axis L. A sleeve 55 is mounted at the edge of the insertion hole 54. The sleeve 55 is cylindrical, extending in the direction of the axis L, and a second internal thread element 88 of an internal thread element 85, which will be described later, is inserted into its inner surface. A recessed section 56 is formed on the outer circumferential surface of the sleeve 55, which is recessed radially inwards. The recessed section 56 fits into the edge of the insertion hole 54.An annular pressure spring 57 is arranged around the entire circumference of the inner surface of the recessed section 56. The pressure spring 57 presses the edge section of the insertion hole 54 towards the underside L2. This secures the sleeve 55 to the second pressure element 50.

[0028] The valve rod element 60 is mounted inside the body 11, which is formed as described above. The valve rod element 60 is an element that forms part of the second screw conveyor element 84 described later, and is tubular in shape such that it extends from the first flow path 17, via the valve port 19, to the second flow path 18. The lower end surface of the valve rod element 60 rests against the upper surface of the first diaphragm 23 at the position of the upper surface L1 of the hub section 39 described above. This clamps the central section of the first diaphragm 23 between the lower end surface of the valve rod element 60 and the upper end surface of the hub section 39 in the direction of the axis L. Projections 60a are formed on the lower surface of the valve rod element 60, projecting towards the lower surface L2.The projections 60a are embedded in the upper surface of the first diaphragm 23 and serve to seal between the valve rod element 60 and the first diaphragm 23. It is also possible that the front end sections of these projections 60a can be understood as the outer circumferential surface of the valve rod element 60 described above, and that the position corresponding to the positions of the front end sections of these projections 60a corresponds to the position of the inner end section 23c2 of the pressure-bearing surface 23c. A central hole 61 is formed in the middle of the valve rod element 60, with axis L serving as the central axis. The valve rod screw 90 is inserted into the central hole 61. A support projection 62 is formed on the outer circumferential surface of the valve rod element 60, projecting radially outwards.A tubular valve cover bracket 63, which surrounds the outer circumferential surface of the valve stem element 60, is mounted at a distance along the axis L in the upper surface L1 of the support projection 62. The upper end surface of the valve cover bracket 63 rests against the lower surface of the second diaphragm 25 to support the second diaphragm 25 from the underside L2.

[0029] At the lower end of the inner circumference of the valve cover bracket 63, as shown in Fig. Figure 4(B) shows a recessed section 63a open towards the underside L2, with an O-ring 63b mounted on the recessed section 63a. The valve element 64 is attached between the support projection 62 and the valve cover holder 63. The valve element 64 is a section that approaches or moves away from the valve port 19 on the top side L1 of the valve port 19 (on a side opposite the first opening section 22) and, in the present embodiment, can be placed on the valve seat section 20. This makes it possible to change the degree of opening of the valve port 19 to 0 or more. The valve element 64 comprises a valve element body 65 that surrounds the outer circumferential surface of the valve stem element 60 and extends radially.

[0030] The valve element body 65 is formed in a thick-plate disc shape. The upper surface of the support projection 62 of the valve stem element 60 rests against the lower surface of the valve element body 65, thus supporting the valve element body 65 from the bottom L2. A valve cover 66, which is integral with the valve element body 65, is mounted in the upper surface L1 of the valve element body 65. The valve cover 66 is formed by bending a metallic sheet material made of stainless steel or the like and covers the upper surface of the valve element body 65, a corner located in the upper surface of the valve element body 65, and part of the side wall of the valve element body 65. The upper surface of the valve cover 66 rests against the lower end surface of the valve cover holder 63 described above and also rests against the lower surface of the O-ring 63b.The valve element 64 is thus integrally formed with the valve stem element 60 and the valve cover holder 63. The lower surface of the valve element 64 forms an opposing surface 67, which is opposite the valve port 19 and the pressure-bearing surface 23c of the first diaphragm 23 in the direction of the axis L. The opposing surface 67 can partially come into contact with a fluid and is designed as a surface that receives a fluid pressure towards the top L1 (towards the side in the direction of the axis L, which is the direction in which the valve element 64 is located away from the valve port 19). The opposing surface 67 can also be designed such that the entire surface can come into contact with a fluid.

[0031] The outer end 67a, which is a radially outer end section of the opposite surface 67 (in the present embodiment being the outer end section of the valve cover 66, but which could also be the outer end section of the valve element body 65), is the outer end section of the valve element 64 in the radial direction. The position of an inner end 67b, which is a radially inner end section of the opposite surface 67, is, in the direction of intersection X, equal to the position of the outer circumferential surface of the valve rod element 60 (of the second screw conveying element 84). That is, the opposite surface 67 extends from the outer end 67a (from the outer end section of the valve element 64 in the radial direction) to the inner end 67b (to the outer circumferential surface of the second screw conveying element 84) in the radial direction of the second screw conveying element 84.In the present embodiment, the position of the inner end 67b of the opposite surface 67 in the intersection direction X corresponds to the position of the outer circumferential surface of the valve stem element 60, but, without being limited thereto, the position of the inner circumferential surface of the O-ring 63b described above, which surrounds the valve stem element 60 in the intersection direction X, may also correspond in the intersection direction X to the position of the inner end 67b of the opposite surface 67. Here, the inner end 67b of the opposite surface 67 is shown in . Fig. 4(B), in the intersection direction X in the same position as the inner end section 23c2 of the pressure-bearing surface 23c, shown in Fig. 4(A), positioned (i.e. in the same position as the position of the outer circumferential surface of the valve stem element 60).

[0032] And the outer end section 23c1 of the pressure-receiving surface 23c (the section which corresponds in the intersection direction X to the inner edge of the first pressure section 34), shown in Fig. 4(A), is radially further outward than the outer end 67a of the opposite surface 67 (the outer end section of the valve cover 66 or the outer end section of the valve element body 65), shown in Fig. 4(B), positioned. This results in a width dimension W1, the dimension from the outer end section 23c1 to the inner end section 23c2 of the pressure-receiving surface 23c, being larger than a width dimension W2, the dimension from the outer end 67a to the inner end 67b of the opposite surface 67, shown in Fig. 4(B). And the area of ​​the pressure-bearing surface 23c is larger than the area of ​​the opposite surface 67.

[0033] Next, the drive section 70 is described. The drive section 70 is a section for driving the valve element 64 in the direction of the axis L and comprises, as shown in Fig. Figure 1 shows a housing 71 arranged in the top L1 of the body 11 and an actuator unit 77 arranged in the top L1 of the housing 71. The housing 71 comprises a top wall 72 extending in the direction of intersection X and cover wall sections 73 extending from the edge section of the top wall 72 to the bottom L2, and is box-shaped. In the center of the top wall 72, a large-diameter hole 72a and a small-diameter hole 72b are formed, extending in the direction of the axis L and starting from the top L1 in that order. The large-diameter hole 72a opens towards the top L1. The small-diameter hole 72b is coaxial with the large-diameter hole 72a and is configured to have a smaller diameter than the large-diameter hole 72a.Paired guide sections 72c are formed in the center of the lower surface of the ceiling wall 72, extending towards the underside L2. The guide sections 72c are arranged in the direction of intersection X at a distance such that the axis L lies in the middle, and are plate-shaped. The surfaces of the guide sections 72c that face inwards in the direction of intersection X form guiding surfaces 72c1, which extend in the direction of the axis L and are opposite each other. A first internal thread element 86, described later, is arranged in a space that is clamped between the paired guiding surfaces 72c1 in the direction of intersection X.

[0034] The cover wall sections 73 extend from the edge section located on the left side X1, the edge section located on the right side X2, the edge section located on the front, and the edge section located on the rear of the ceiling wall 72 towards the underside L2 and are plate-shaped. The lower end sections of the cover wall sections 73 abut the upper surface of the lower plate section 51 of the second pressure element 50 described above.

[0035] Inside the housing 71, collars 74 are mounted, extending in the direction of the axis L. The collars 74 are mounted in the corner sections located in the housing 71, which are formed by connecting the cover wall sections 73, and extend in the direction of the axis L. The collars 74 are sections into which stop screws 76, described later, are inserted and serve as reinforcing elements that reduce deformation of the housing 71 due to stress generated when the stop screws 76 are tightened. A substantially rectangular, plate-shaped bracket 75 is mounted on the upper surface of the housing 71. A through-hole 75a is formed in the center of the bracket 75, extending in the direction of the axis L. Through-holes (not shown) are also formed at the four corners of the upper surface of the bracket 75, and the stop screws 76 are inserted into these through-holes.

[0036] The stop screws 76 are screws that integrally connect the bracket 75, the housing 71, the second pressure element 50, the second diaphragm 25, and the body 11. They extend through the collars 74 in the direction of the axis L and are attached to the upper surface 11b of the body 11. By tightening the stop screws 76, the stop screws 76, the bracket 75, the housing 71, the second pressure element 50, the second diaphragm 25, and the body 11 are integrally connected. A force generated by tightening the stop screws 76 can also be received by the collars 74 to reduce deformation of the housing 71. Furthermore, the lower plate section 51 of the second pressure element 50 rests against the upper surface of the second diaphragm 25, while the projecting section 52 is embedded in the upper surface of the second diaphragm 25.And the lower plate section 51 of the second pressure element 50 is pressed against the upper surface of the second membrane 25 towards the underside L2.

[0037] This presses the second membrane 25 against the circumferential edge of the second opening section 24. The actuator unit 77 is mounted in the top L1 of the housing 71. The actuator unit 77 is a section that exerts a rotational force, which serves as a driving force, on the screw conveyor unit 80 and is formed, for example, by a stepper motor. The actuator unit 77 comprises, as shown in Fig. Figure 2 shows a box-shaped housing 77a, which accommodates a stator coil (not shown) or the like, and is attached to the bracket 75 by stop screws 78. A pulse is applied to the actuator unit 77 via guide wires 79, which extend inside and outside the housing 77a, causing the spindle 81 described later to rotate.

[0038] Next, the screw conveyor unit 80 will be described. The screw conveyor unit 80 is, as shown in Fig. Figure 1 shows a unit that transmits a driving force from the drive section 70 to the valve element 64 and comprises the spindle 81 (the first screw conveyor element) and the second screw conveyor element 84, each made of a metallic material such as stainless steel or the like and extending in the direction of the axis L. The upper end section of the spindle 81 is inserted into the through-hole 75a of the bracket 75 and extends in the direction of the axis L to be connected to the actuator unit 77. In the section of the spindle 81 located in the upper surface L1, a section with an enlarged diameter 81a is formed, which has a larger diameter than other parts of the spindle 81.The enlarged diameter section 81a is positioned where it is clamped between the lower surface of the bracket 75 and the lower surface of the large diameter hole 72a of the housing 71 in the direction of the axis L. An annular thrust washer 82 is arranged on both the upper and lower surfaces of the enlarged diameter section 81a.

[0039] The upper surface of the thrust washer 82 located in the top surface L1 rests against the lower surface of the bracket 75, thus limiting any displacement of the thrust washer 82 towards the top surface L1. The lower surface of the thrust washer 82 located in the bottom surface L2 rests against the lower surface of the large-diameter hole 72a, thus limiting any displacement of the thrust washer 82 located in the bottom surface L2 towards the bottom surface L2. This configuration results in the spindle 81 rotating about the axis L in a state where displacement in the direction of the axis L is limited when the actuator unit 77 is driven. An external thread 83 is formed on the outer circumferential surface of the section of the spindle 81 located in the bottom surface L2.The second screw conveyor element 84 is an element that is displaceable in the direction of the axis L by a rotational force of the spindle 81 and comprises the internally threaded element 85, the valve rod screw 90 and the valve rod element 60 described above. The internally threaded element 85 comprises the first internally threaded element 86, which forms the section located in the top L1, the second internally threaded element 88, which forms the section located in the bottom L2, and a connecting element 89, which connects the first internally threaded element 86 to the second internally threaded element 88.

[0040] The first internal thread element 86 is, as in Fig. Figure 5 shows the assembly arranged in a space clamped between the guiding surfaces 72c1 of the guide sections 72c of the housing 71 in the intersection direction X. The first internal thread element 86 comprises an outer forming section 86a, which is tubular in shape and extends in the direction of the axis L with a metallic material. Guided surfaces 86a2 are partially formed in the outer forming section 86a and are formed by a planar surface extending in the direction of the axis L. The guided surfaces 86a2 are formed by cutting or the like on a portion of the unmachined arcuate outer circumferential surface 86a1 of the outer forming section 86a, shown by an imaginary line, in the direction of the axis L.The guided surfaces 86a2 can slide on the guiding surfaces 72c1 of the guide sections 72c, and by this sliding the first internal thread element 86 cannot rotate about the axis L and the first internal thread element 86 can move up and down in the direction of the axis L.

[0041] A resin-coated inner tube section 86b is arranged on the inner circumferential surface of the outer mold section 86a. The inner tube section 86b is integrally formed with the outer mold section 86a by insert molding. A spiral groove 86c, extending around the axis L, is formed at the boundary between the outer mold section 86a and the inner tube section 86b. The spiral groove 86c limits the relative rotation between the outer mold section 86a and the inner tube section 86b around the axis L during insert molding. This design also prevents the inner tube section 86b from falling out by increasing the contact area between the inner tube section 86b and the outer mold section 86a compared to a design without the spiral groove 86c. An internal thread 86d is formed on the inner circumferential surface of the inner tube section 86b.The internal thread 86d is screwed to the external thread 83 of the spindle 81. Through this screw connection, the spindle 81 is connected to the second screw conveying element 84. The rotation of the spindle 81 about the axis L results in screw conveying of the internal thread 86d and thus in a movement of the internal thread element 85 in the direction of the axis L in a state in which rotation about the axis L is limited.

[0042] In the lower end section of the outer mold section 86a, a first flange section 87 is formed, extending radially outwards. Pin holes 87a are formed on the lower surface of the first flange section 87, opening towards the underside L2. The pin holes 87a are holes for inserting pins (not shown) that are provided on the side of the mold during insert molding of the inner tube section 86b and serve as positioning holes that prevent displacement of the outer mold section 86a during insert molding. The second internal threaded element 88 is tubular and made of a metallic material extending in the direction of the axis L. In the upper end section of the second internal threaded element 88, a second flange section 88a is formed, extending radially outwards.The second flange section 88a is configured such that it has a larger diameter than the first flange section 87 of the first internal thread element 86, and the upper surface of the second flange section 88a rests against the lower surface of the first flange section 87. As shown in . Fig. As shown in Figure 1, the section of the second internal threaded element 88 that is located further into the underside L2 than the second flange section 88a is inserted into the central section of the sleeve 55 described above. A connecting internal thread 88b is formed in the center of the second internal threaded element 88.

[0043] As in Fig. As shown in Figure 5, the connecting element 89 is substantially L-shaped in cross-sectional view along the direction of axis L to cover the upper and side surfaces of the first flange section 87 and part of the upper surface of the second flange section 88a. A side wall 89a of the connecting element 89 is arranged at a distance from the first flange section 87 in the direction of intersection X and extends in the direction of axis L. The lower end section of the side wall 89a is connected to the upper surface of the second flange section 88a by welding or the like. An upper wall 89b of the connecting element 89 extends inward from the upper end of the side wall 89a in the direction of intersection X.The upper wall 89b is arranged in the direction of axis L at a distance from the first flange section 87 of the first internal threaded element 86 and in the intersection direction X at a distance from the outer formed section 86a of the first internal threaded element 86. With this arrangement, the second internal threaded element 88 and the connecting element 89 are connected to the first internal threaded element 86 with clearance in the direction of axis L and in the intersection direction X.

[0044] Due to this connection, the second internal thread element 88 is displaceable in the direction of axis L and in the intersection direction X relative to the first internal thread element 86; therefore, the valve element 64, which is integrally connected to the second internal thread element 88 via the valve rod screw 90 described later, can displace in the direction of axis L and in the intersection direction X. This means that a control movement of the valve element 64 in the direction of axis L and in the intersection direction X is possible. Even if, for example, the spindle 81 and the valve rod screw 90 are axially displaced, the axial displacement in question can therefore be absorbed by the aforementioned control movement, thus preventing the actuator section 70 from locking and reducing the load exerted on the actuator section 70.Furthermore, by absorbing the aforementioned axial displacement through the aforementioned control movement, an inclination of the valve element 64 or the like can be reduced, thereby ensuring stable sealing performance due to the valve element 64.

[0045] As in Fig. As shown in Figure 1, the valve rod screw 90 is a screw that serves to join, starting from the underside L2, the hub section 39, the first diaphragm 23, the valve rod element 60, the valve element 64, the valve cover holder 63, and the second diaphragm 25 in one piece, and to connect these together with the second internally threaded element 88. A head section 91 of the valve rod screw 90 is arranged in the second through-hole 39b of the hub section 39. A spring washer 92 and a washer 93 are arranged between the upper surface of the head section 91 and the lower surface of the step section 39c of the hub section 39.

[0046] In the middle of the head section 91, the shaft section 94 is formed, which extends towards the top L1. The shaft section 94 extends through the first through-hole 39a of the hub section 39, the hole section 23a of the first diaphragm 23, the central hole 61 of the valve stem element 60 and the second hole section 25a of the second diaphragm 25 to the top L1 of the second diaphragm 25. On the outer circumferential surface of the shaft section 94, a connecting external thread 95 is formed in a section that is located further into the top surface L1 than the second diaphragm 25. The connecting external thread 95 is screwed to the connecting internal thread 88b of the second internal threaded element 88, whereby the second internal threaded element 88, the hub section 39, the first diaphragm 23, the valve rod element 60, the valve element 64, the valve cover bracket 63, the second diaphragm 25 and the valve rod screw 90 are formed in one piece.The connecting external thread 95 does not necessarily have to be formed in the section that is located further in the top surface L1 than the second diaphragm 25, but can be formed on the entire outer circumferential surface of the shaft section 94.

[0047] Next, the operation of the valve device 1 is described. In this valve device 1, the pressure in the housing 71, in the first pressure element 30, and in the cap 40 is equal to atmospheric pressure. Due to a fluid flowing from the first flow path 17 into the second flow path 18, the pressure in the first flow path 17 and in the second flow path 18 is higher than atmospheric pressure. As shown in Fig. As shown in Figure 1, the valve element 64 is in a state where it is placed on the valve seat section 20, the valve port 19 is closed, and the flow of a fluid from the first flow path 17, which has a higher pressure, into the second flow path 18 is interrupted. When a pulse is applied to the actuator unit 77 in this state, the spindle 81 rotates about the axis L in a state where displacement in the direction of the axis L is limited. The rotation of the spindle 81 leads to screw advancement of the internal thread 86d, which is screwed to the external thread 83, and thus to a displacement of the first internal thread element 86 towards the top L1.

[0048] This causes the second internal thread element 88, which, as described above, is connected to the first internal thread element 86 with clearance in the direction of axis L and in the intersection direction X, and the hub section 39, the first diaphragm 23, the valve stem element 60, the valve element 64, the valve cover bracket 63, the second diaphragm 25, and the valve stem screw 90, which are integral with the second internal thread element 88, to shift towards the top L1. During this process, the central section of the first diaphragm 23 and that of the second diaphragm 25 deform towards the top L1. This shift and deformation gradually raises the valve element 64, and the valve port 19 gradually opens. Applying the pulse mentioned above then causes the spindle 81 to rotate backward.This causes the first internal thread element 86, the second internal thread element 88, the hub section 39, the first diaphragm 23, the valve stem element 60, the valve element 64, the valve cover bracket 63, the second diaphragm 25, and the valve stem screw 90 to shift towards the underside L2 by screw movement. Then, the central section of the first diaphragm 23 and that of the second diaphragm 25 deform towards the underside L2. This gradually lowers the valve element 64, resulting in the valve closing.

[0049] In the present embodiment, the second internal thread element 88, which, as described above, is connected to the first internal thread element 86 with a clearance, is integrally connected (one-piece) to the hub section 39, the first diaphragm 23, the valve stem element 60, the valve element 64, the valve cover bracket 63, the second diaphragm 25, and the valve stem screw 90. A displacement of the valve element 64 and the respective components integrally connected to the valve element 64 in the direction of axis L is therefore coupled to a deformation of the first diaphragm 23. And in this configuration, as described in Fig. 4(A) and Fig. As shown in Figure 4(B), the area of ​​the pressure-bearing surface 23c is larger than the area of ​​the opposite surface 67. Therefore, the equilibrium between a force exerted on the pressure-bearing surface 23c due to fluid pressure and a force exerted on the opposite surface 67 due to fluid pressure is disturbed. As a result, a force with which a fluid biases the valve element 64 towards the bottom L2 (the approach side mentioned above) via the pressure-bearing surface 23c is greater than a force with which a fluid biases the valve element 64 towards the top L1 (the distance side mentioned above) via the opposite surface 67, thus almost balancing a force with which the valve element 64 is to be lifted towards the distance side in question.

[0050] This allows the valve element 64 to be preloaded towards the underside L2, and the second internal threaded element 88, which is integrally connected to the valve element 64, can also be preloaded towards the underside L2. Therefore, it is possible to press the valve element 64 towards the side of the valve port 19 and to operate the actuator section 70 in a state where any play in the direction of axis L, such as play between the external thread 83 of the spindle 81 and the internal thread 86d of the internal threaded element 85, play between the first flange section 87 of the first internal threaded element 86 and the connecting element 89, or any other play, is reduced. Consequently, unintentional lifting of the valve element 64 can be reduced, as can unintentional valve opening and the generation of hysteresis caused by a phenomenon that makes valve closure more difficult.In the present embodiment, as described above, when the valve closes, i.e., when the valve port 19 is closed, the internal pressure of the first flow path 17 is higher than the internal pressure of the second flow path 18. Therefore, when the valve opens, i.e., when the valve port 19 is open, a jet of fluid can be generated, bubbling from the first flow path 17 into the second flow path 18. However, according to this design, the valve opening can occur in a state where the valve element 64 is pressed towards the side of the valve port 19, and any clearance in the direction of axis L, such as that of the screw conveyor 80, is reduced. This reduces any unintentional lifting of the valve element 64 corresponding to the aforementioned clearance in the direction of axis L. This can also stabilize the behavior of the valve element 64 immediately before and after the valve opening.

[0051] If the area of ​​the pressure-bearing surface 23c is too large, the driving force required to move the valve element 64 towards the distance side is too great; therefore, the area of ​​the pressure-bearing surface 23c is preferably set such that it is greater than 1.0 times the area of ​​the opposite surface 67 and less than or equal to 4.0 times the area of ​​the opposite surface 67. If the area of ​​the pressure-bearing surface 23c is greater than 1.0 times the area of ​​the opposite surface 67, the following can be achieved: A force with which a fluid biases the valve element 64 towards the bottom L2 via the pressure-bearing surface 23c can be greater than a force with which a fluid biases the valve element 64 towards the top L1 via the opposite surface 67, thereby suitably reducing the lifting of the valve element 64.Furthermore, if the area of ​​the pressure-bearing surface 23c is less than or equal to 4.0 times the area of ​​the opposite surface 67, the force with which a fluid biases the valve element 64 towards the underside L2 via the pressure-bearing surface 23c can be reduced so as not to increase too much.

[0052] Next, the flow rate characteristic of valve device 1 will be described. Fig. Figure 6 is a diagram showing the flow rate characteristic of the valve device 1. The flow rate characteristic is a value represented by the flow rate of a fluid passing through the valve port 19 as a function of an operating parameter of the spindle 81 (i.e., an operating parameter of the actuator section 70); and Fig. Figure 6 shows a change in the flow rate characteristic for each operating size. The diagram is shown in Fig. Figure 6 represents the horizontal axis, an operating parameter of the spindle 81 in the valve opening direction, and the vertical axis represents the flow rate of a fluid flowing through the valve port 19. As shown in the diagram in Fig. Figure 6, shown with solid lines, depicts the flow rate characteristic as it comprises an opening direction characteristic A1, which shows a change in the flow rate characteristic when the valve opens, and a closing direction characteristic A2, which shows a change in the flow rate characteristic when the valve closes. The opening direction characteristic A1 does not completely correspond to the closing direction characteristic A2. This is because the valve element 64 moves relatively easily in the valve opening direction but with difficulty in the valve closing direction. This is because the movement of the valve element 64 in the valve opening direction corresponds to the flow direction of a fluid flowing from the first flow path 17 to the second flow path 18, whereas the movement of the valve element 64 in the valve closing direction is opposite to the flow direction of the fluid.

[0053] In the present embodiment, the difference between the opening direction characteristic A1 and the closing direction characteristic A2 is referred to as hysteresis H1. Hysteresis H1 indicates the degree of difficulty of valve closure. In the present embodiment, hysteresis H1 is significantly reduced compared to a conventional hysteresis H2, which is shown in the diagram in Fig.Figure 6 is represented by a dotted line and is generated by a closing direction characteristic a2 of a conventional valve device. This is because, as described above, the balance between a force exerted on the pressure-bearing surface 23c due to fluid pressure and a force exerted on the opposite surface 67 due to fluid pressure is disturbed. Specifically, the force with which a fluid biases the valve element 64 towards the bottom L2 (the approach side mentioned above) via the pressure-bearing surface 23c is greater than the force with which a fluid biases the valve element 64 towards the top L1 (the distance side mentioned above) via the opposite surface 67, and the force with which the valve element 64 is to be lifted towards the distance side is almost balanced. This allows the hysteresis H1 to be significantly reduced compared to the hysteresis H2.

[0054] According to the embodiment described above, the second screw conveying element 84 and the valve element 64 are integrally connected, and the second screw conveying element 84 and the first diaphragm 23 (the sealing element) are also integrally connected. Therefore, a displacement of the second screw conveying element 84 and the valve element 64 in the direction of axis L is coupled to a deformation of the first diaphragm 23 in the direction of axis L. In this configuration, the area of ​​the pressure-bearing surface 23c of the first diaphragm 23 is larger than the area of ​​the opposite surface 67 of the valve element 64. Therefore, the equilibrium between a force exerted on the pressure-bearing surface 23c due to fluid pressure and a force exerted on the opposite surface 67 due to fluid pressure can be disrupted.This results in a force with which a fluid biases the valve element 64 towards the underside L2 (towards the side of the valve port 19 (the approach side)) via the pressure-bearing surface 23c, being greater than a force with which a fluid biases the valve element 64 towards the top side L1 (towards the side opposite the valve port 19 (the distance side)) via the opposite surface 67, thus balancing a force with which the valve element 64 is to be lifted towards the respective distance side. Therefore, an opening / closing operation of the valve port 19 can be carried out in a state in which the valve element 64 is pressed towards the side of the valve port 19 and any clearance in the direction of the axis L, such as clearance of the screw conveyor unit 80, is reduced.Consequently, an unintentional lifting of the valve element 64 can be reduced, and an unintentional valve opening and the generation of the hysteresis H1 can be reduced, so that the valve device 1 can be provided which is able to stably control the flow rate of a fluid.

[0055] According to the embodiment described above, the pressure-receiving surface 23c is further configured as a surface that receives fluid pressure towards the underside L2, and the opposite surface 67 is configured as a surface that receives fluid pressure towards the top L1. According to this configuration, the pressure-receiving surface 23c, which receives fluid pressure towards the side closest to the axis L, can be larger than the opposite surface 67, which receives fluid pressure towards the side furthest from the axis L. This allows a force with which a fluid biases the valve element 64 towards the side of the valve port 19 via the pressure-receiving surface 23c to be greater than a force with which a fluid biases the valve element 64 towards the side opposite the valve port 19 via the opposite surface 67.

[0056] According to the embodiment mentioned above, the pressure-bearing surface 23c, which extends from the outer end section 23c1 (from the section corresponding to the inner edge of the first pressure section 34) to the inner end section 23c2 (to the outer circumferential surface of the second screw conveying element 84), can also be larger than the opposite surface 67, which extends from the outer end 67a (from the outer end section of the valve element 64 in a radial direction) to the inner end 67b (to the outer circumferential surface of the second screw conveying element 84), whereby a force with which a fluid biases the valve element 64 towards the side of the valve port 19 via the pressure-bearing surface 23c can be greater than a force with which a fluid biases the valve element 64 towards the side opposite the valve port 19 via the opposite surface 67.

[0057] According to the embodiment described above, the valve device 1, in which a jet of fluid is generated when the valve opens (i.e., when the valve port 19 is open) and flows from the first flow path 17 into the second flow path 18, can achieve the following: The valve opening can occur in a state where the valve element 64 is pressed towards the side of the valve port 19 and any play in the direction of the axis L, such as the play of the screw conveyor 80, is reduced. This reduces any unintentional lifting of the valve element 64 in the direction of the axis L, as described above. This can stabilize the behavior of the valve element 64 immediately before and after the valve opening.

[0058] According to the embodiment described above, by making the area of ​​the pressure-bearing surface 23c larger than 1.0 times the area of ​​the opposite surface 67, the force with which a fluid biases the valve element 64 towards the bottom L2 via the pressure-bearing surface 23c can be greater than the force with which a fluid biases the valve element 64 towards the top L1 via the opposite surface 67, thereby suitably reducing the lifting of the valve element 64. Furthermore, by making the area of ​​the pressure-bearing surface 23c less than or equal to 4.0 times the area of ​​the opposite surface 67, the force with which a fluid biases the valve element 64 towards the bottom L2 via the pressure-bearing surface 23c can be reduced from becoming excessively high.Therefore, the driving force of the drive section 70 for driving the valve element 64 can be reduced so that the driving of the valve element 64 can be carried out smoothly.

[0059] The embodiment of the present invention has been described in more detail with reference to the drawings as above; however, the specific structure is not limited to this, but changes in design etc. are also within the scope of the present invention, without deviating from the basic idea of ​​the present invention.

[0060] In the present embodiment, for example, the position of the inner end section 23c2 of the pressure-receiving surface 23c is the position that, in the direction of the axis L, is equal to the position of the outer circumferential surface of the valve rod element 60. However, without being limited thereto, as described above, the position that, in the direction of the axis L, is equal to the positions of the front end sections of the projections 60a of the lower surface of the valve rod element 60 can correspond to the position of the inner end section 23c2. In the present embodiment, the position of the inner end 67b of the opposite surface 67 is also the position that, in the direction of the axis L, is equal to the position of the outer circumferential surface of the valve rod element 60.However, without being limited to this, as described above, the position of the inner circumferential surface of the O-ring 63b, which surrounds the valve stem element 60, can correspond in the direction of the axis L to the position of the inner end 67b.

[0061] It is also possible that the position of the outer end 67a of the opposite surface 67 is, for example, in the direction of the axis L, the same as the position of the contact section 21 of the valve seat section 20. That is, it is also possible that the opposite surface 67 extends from the outer end 67a (from the section that corresponds to the contact section 21 in the direction of the axis L) to the inner end 67b (to the outer circumferential surface of the second screw conveying element 84) in the radial direction of the second screw conveying element 84.According to this design, particularly during valve closure, the force exerted by a high-pressure fluid of the first flow path 17 across the pressure-bearing surface 23c, which biases the valve element 64 towards the side of the valve port 19, can be greater than the force exerted by a high-pressure fluid of the first flow path 17 across the opposite surface 67, which biases the valve element 64 towards the side opposite the valve port 19. Therefore, when the valve closes, i.e., when the valve port 19 is closed, the valve opening can occur in a state where the valve element 64 is pressed towards the side of the valve port 19, thus eliminating the aforementioned clearance in the direction of axis L. Consequently, unwanted lifting of the valve element 64 can be reduced, and the generation of a distortion in the opening direction characteristic A1 (fluid characteristic) can be minimized. [List of reference symbols] L axis 1 Valve device 10 valve bodies 17 first flow path 18 second flow path 19 Valve connection 22 first opening section (opening section) 23 first membrane (sealing element) 23c print area 67 opposite area 64 Valve element 70 Drive section 80 screw conveyor unit 81 Spindle (first screw conveyor element) 84 second screw conveyor element QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 6-109163

[0004]

Claims

[1] Valve device comprising a valve body comprising a valve port through which a fluid flows and an opening section opposite the valve port, a valve element which approaches or moves away from the valve port on a side opposite the opening section, a drive section for driving the valve element and a screw conveying unit for transmitting a drive force from the drive section to the valve element, characterized by , that the screw conveying unit comprises a first screw conveying element which rotates about an axis due to the driving force, and a second screw conveying element which is connected to the first screw conveying element and is displaceable in one direction of an axis, that the second screw conveying element is integral with the valve element and also extends from a second flow path, in which the valve element is located, via the valve connection to a first flow path, in which the opening section is located, that a sealing element is provided in a section of the second screw conveying element located in the first flow path, which closes the opening section and is also deformable in the direction of the axis, that the sealing element includes a pressure-bearing surface that is opposite the valve port and the valve element and comes into contact with the fluid, that the valve element comprises an opposing surface that is opposite the valve port and the pressure receiving surface, and that the area of ​​the pressure-bearing surface is larger than the area of ​​the opposite surface. [2] Valve device according to claim 1, characterized by , that the pressure-receiving surface is formed as a surface that receives a fluid pressure towards an approach side of the direction of the axis, which is a direction in which the valve element approaches the valve port, and that the opposite surface is formed as a surface that receives a fluid pressure towards a distance side of the direction of the axis, which is a direction in which the valve element moves away from the valve port. [3] Valve device according to claim 2, comprising a pressure section which presses the sealing element against an opening circumferential edge of the opening section, characterized by that the pressure-bearing surface extends from a section corresponding to an inner edge of the pressure section in the direction of the axis to an outer circumferential surface of the second screw conveying element in a radial direction of the second screw conveying element, that the valve element extends in the radial direction of the second screw conveying element, and that the opposite surface extends from an outer end section of the valve element in the radial direction to the outer circumferential surface of the second screw conveying element in the radial direction. [4] Valve device according to claim 1, characterized by , that when a valve closes, namely when the valve connection is closed by the valve element, the internal pressure of the first flow path is higher than the internal pressure of the second flow path. [5] Valve device according to any one of claims 1 to 4, characterized by , that the area of ​​the pressure-bearing surface is greater than 1.0 times the area of ​​the opposite surface and less than or equal to 4.0 times the area of ​​the opposite surface.

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