Valve gear

Abstract

To provide a valve gear which can control a flow rate of a fluid stably.SOLUTION: A valve gear 1 includes: a valve body 10 including a valve port 19 and a first opening 22; a valve disc 64; and a screw feeding mechanism 80. The screw feeding mechanism 80 includes: a spindle 81 which rotates around an axis; and a second screw feeding member 84 which may be displaced in an axis L direction. The second screw feeding member 84 is integrated with the valve disc 64 and extends from a second passage 18, in which the valve disc 64 is located, to a first passage 17, in which a first opening 22 is located, through the valve port 19. The second screw feeding member 84 is provided with a first diaphragm 23 which closes the first opening 22. The first diaphragm 23 includes a pressure receiving surface 23c which faces the valve disc 64 and contacts with a fluid. The valve disc 64 includes a facing surface 67 facing the pressure receiving surface 23c. An area of the pressure receiving surface 23c is larger than an area of the facing surface 67.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, valve devices for controlling the flow of a fluid are known (see, for example, Patent Document 1). The flow rate control valve (valve device) described in Patent Document 1 includes a valve body 12, as shown in FIG. 1 of Patent Document 1, which includes a primary flow path 24 through which a fluid flows, a main valve seat 14 with a flow path opening communicating with the primary flow path 24, and a secondary flow path 26 communicating with the flow path opening of the main valve seat 14. The flow rate control valve also includes a main valve 30 that changes the opening of the flow path by moving toward or away from the main valve seat 14 within the valve body 12, and a pilot valve mechanism 100 that moves the main valve 30 back and forth in the axial direction. The main valve 30 includes a disk-shaped main valve element 34 located on the primary flow path 24 side, and a fastener 39 that extends axially from the center of the main valve element 34 through the flow path opening of the main valve seat 14 and is located on the secondary flow path 26 side. A secondary diaphragm 50 is attached to the fastener 39, and is disposed concentrically opposite the main valve 30 and extends perpendicular to the axial direction.

[0003] The pilot valve mechanism 100 includes a drive shaft 121 that moves axially by screw feed, a pilot passage 72 provided in the main valve 30 so as to be opened and closed by the drive shaft 121, and a back pressure chamber 27 that communicates with the pilot passage 72 and the primary passage 24. When the pilot passage 72 opens by screw feed of the drive shaft 121, fluid in the back pressure chamber 27 flows into the pilot passage 72, causing the pressure in the back pressure chamber 27 to become lower than the pressure in the primary passage 24, displacing the main valve 30 axially upward and opening the valve. As a result, fluid flows from the primary passage 24, which has a higher pressure, toward the secondary passage 26. On the other hand, when the pilot passage 72 is closed, the pressure in the back pressure chamber 27 becomes greater than the pressure in the primary passage 24, causing the main valve 30 to displace axially downward and close. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-109163 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described flow control valve, the area of ​​the portion of the main valve 30 facing the secondary-side flow path 26 is the same as the area of ​​the pressure-receiving surface of the secondary-side diaphragm 50 facing the main valve 30. Therefore, when the main valve 30 is seated, the pressure of the secondary-side flow path 26 is applied to the main valve 30 directly in an upward axial direction via the portion facing the secondary-side flow path 26, and the pressure of the secondary-side flow path 26 is applied to the main valve 30 in a downward direction via the secondary-side diaphragm 50. In other words, the upward force applied directly to the main valve 30 from the secondary-side flow path 26 and the downward force applied to the main valve 30 via the secondary-side diaphragm 50 are balanced, and the main valve 30 is not biased in either axial direction from the secondary-side flow path 26 side. Therefore, it is possible to drive the main valve 30 with a relatively small driving force.

[0006] However, with this configuration, when the drive shaft 121 is threaded to open the main valve 30, if the pressure in the backpressure chamber 27 decreases, the main valve 30 is not biased in either axial direction from the secondary-side flow path 26, as described above. This means that the main valve 30 is likely to lift up in the axial direction due to axial play, such as play in the threads of the drive shaft 121, and the valve may open with an unintended amount of operation of the drive shaft 121. Furthermore, with this configuration, for example, when fluid flows from the secondary-side flow path 26 to the primary-side flow path 24, the main valve 30 is pushed up in the inflow direction by the fluid flowing into the primary-side flow path 24 from the flow path opening when the main valve 30 is closed from the maximum valve open state. This makes it difficult for the main valve 30 to close due to the play in the axial direction L, which tends to cause hysteresis. This means that the change in the flow path characteristics, which is expressed as the flow rate of fluid passing through the flow path opening relative to the amount of operation of the drive shaft 121, tends to diverge between when the valve is open and when it is closed. Therefore, it is difficult to stably control the flow rate of the fluid.

[0007] An object of the present invention is to provide a valve device that can stably control the flow rate of a fluid. [Means for solving the problem]

[0008] In order to solve the above problems and achieve the object, the valve device of the present invention is a valve device comprising: a valve body having a valve port through which a fluid passes and an opening facing the valve port; a valve element that approaches or moves away from the valve port on the opposite side of the opening; a drive unit that drives the valve element; and a screw feed mechanism that transmits the drive force of the drive unit to the valve element, wherein the screw feed mechanism comprises a first screw feed member that rotates about its axis by the drive force, and a second screw feed member that is connected to the first screw feed member and is displaceable in the axial direction, The feed member is integrated with the valve body and extends from the second flow path in which the valve body is located, through the valve port, to the first flow path in which the opening is located, and a sealing member that closes the opening and is deformable in the axial direction is provided at a portion of the second screw feed member located in the first flow path, and the sealing member has a pressure-receiving surface that faces the valve port and the valve body and comes into contact with the fluid, and the valve body has an opposing surface that faces the valve port and the pressure-receiving surface, and the area of ​​the pressure-receiving surface is larger than the area of ​​the opposing surface.

[0009] According to the present invention, the second feed screw member and the valve disc are integrated, and the second feed screw member and the sealing member are integrated, so that the axial displacement of the second feed screw member and the valve disc is linked to the axial deformation of the sealing member. In this configuration, the area of ​​the pressure-receiving surface of the sealing member is larger than the area of ​​the opposing surface of the valve disc, which can unbalance the force applied to the pressure-receiving surface by fluid pressure and the force applied to the opposing surface by fluid pressure. This makes the force with which the fluid urges the valve disc toward the valve port (the proximal side) via the pressure-receiving surface greater than the force with which the fluid urges the valve disc toward the opposite side from the valve port (the distal side) via the opposing surface, thereby canceling the force that tends to lift the valve disc toward the distal side. This allows the valve disc to be pressed toward the valve port, reducing axial play, such as play in the feed screw mechanism, and allows the valve port to be opened and closed. Therefore, it is possible to prevent the valve element from unintentionally floating up, thereby preventing unintentional valve opening and the occurrence of hysteresis, and to provide a valve device that can stably control the flow rate of fluid.

[0010] In this case, it is preferable that the pressure-receiving surface be configured as a surface that receives fluid pressure toward the proximal side in the axial direction, which is the direction in which the valve disc approaches the valve port, and the opposing surface be configured as a surface that receives fluid pressure toward the distal side in the axial direction, which is the direction in which the valve disc moves away from the valve port. With this configuration, the pressure-receiving surface that receives fluid pressure toward the proximal side in the axial direction can be made larger than the opposing surface that receives fluid pressure toward the distal side in the axial direction, so that the force with which the fluid urges the valve disc toward the valve port via the pressure-receiving surface can be made larger than the force with which the fluid urges the valve disc away from the valve port via the opposing surface.

[0011] Preferably, the valve element further includes a pressing portion that presses the sealing member against the periphery of the opening, the pressure-receiving surface extending in a radial direction of the second feed screw member from a portion corresponding to an inner edge of the pressing portion in the axial direction to an outer peripheral surface of the second feed screw member, the valve element extends in the radial direction of the second feed screw member, and the opposing surface extending in the radial direction from an outer end of the valve element in the radial direction to the outer peripheral surface of the second feed screw member. With this configuration, the pressure-receiving surface extending from the portion corresponding to the inner edge of the pressing portion to the outer peripheral surface of the second feed screw member is larger than the opposing surface extending from the outer end of the valve element in the radial direction to the outer peripheral surface of the second feed screw member, and the force with which the fluid urges the valve element toward the valve port via the pressure-receiving surface can be larger than the force with which the fluid urges the valve element away from the valve port via the opposing surface.

[0012] Furthermore, when the valve port is closed by the valve element, the internal pressure of the first flow path may be higher than the internal pressure of the second flow path. With this configuration, when the valve port is open, a jet of fluid may be generated, in which the fluid sprays up from the first flow path to the second flow path. However, with this configuration, as described above, the valve element is pressed toward the valve port, allowing the valve to be opened with axial play, such as play in the screw feed mechanism, reduced. This prevents the valve element from unintentionally rising up by the amount of play in the axial direction. This stabilizes the behavior of the valve element immediately before and after the valve is opened.

[0013] Furthermore, it is preferable that the area of ​​the pressure-receiving surface be greater than 1.0 times the area of ​​the opposing surface but not greater than 4.0 times the area of ​​the opposing surface. According to this configuration, by making the area of ​​the pressure-receiving surface greater than 1.0 times the area of ​​the opposing surface, the force with which the fluid urges the valve disc toward the valve port via the pressure-receiving surface can be made greater than the force with which the fluid urges the valve disc away from the valve port via the opposing surface, thereby effectively preventing the valve disc from lifting up. Furthermore, by making the area of ​​the pressure-receiving surface not greater than 4.0 times the area of ​​the opposing surface, the force with which the fluid urges the valve disc toward the valve port via the pressure-receiving surface can be prevented from becoming too large. This prevents the drive force of the drive unit that drives the valve disc from becoming too large, allowing the valve disc to be driven smoothly. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a valve device that can stably control the flow rate of a fluid. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view of a valve device according to an embodiment of the present invention taken along the axis of a spindle. [Figure 2] FIG. [Figure 3] FIG. 3 is a perspective view of a first pressing member that constitutes a part of the valve device. [Figure 4] 1A is an enlarged cross-sectional view of the first diaphragm, and FIG. 1B is an enlarged cross-sectional view of the valve body. [Figure 5] FIG. 2 is an enlarged cross-sectional view of region A in FIG. 1. [Figure 6] 4 is a graph showing flow characteristics of a valve device. DETAILED DESCRIPTION OF THE INVENTION

[0016] A valve device 1 according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 6. The valve device 1 is an electrically operated valve disposed in a portion of a piping line through which a fluid such as a liquid or gas flows, and is used to adjust the flow rate of the fluid. In the following description, the direction along the axis L of a spindle 81 (first screw feed member) and a second screw feed member 84 (described later) will be referred to as the "axial L direction." One side of the axial L direction will be referred to as the "upper side L1," and the other side will be referred to as the "lower side L2." A direction intersecting the axial L direction will be referred to as the "intersecting direction X." The intersecting direction X also corresponds to the radial direction around the axis L. One side of the intersecting direction X will be referred to as the "left side X1," and the other side will be referred to as the "right side X2." These definitions of directions are provided solely for the convenience of description and do not necessarily correspond to the directions in the actual use state of the valve device 1, and do not limit the directions of the valve device 1.

[0017] As shown in FIG. 1 , the valve device 1 includes a valve body 10 having a valve port 19 through which a fluid passes, a valve element 64 located inside the valve body 10 and spaced apart from the valve port 19 along an axis L, and a drive unit 70 that drives the valve element 64. The valve device 1 also includes a screw feed mechanism 80 that transmits the drive force of the drive unit 70 to the valve element 64. The valve body 10 includes a cylindrical main body 11 extending in the transverse direction X. A first port 12 that opens in the transverse direction X is formed at the left end (X1) of the main body 11. A female thread (not shown) is formed on the inner circumferential surface of the first port 12, and a first coupling pipe (not shown) is connected to the first port 12 by threading onto the female thread. A second port 13 that opens in the transverse direction X is formed at the right end (X2) of the main body 11. A female thread (not shown) is formed on the inner peripheral surface of the second port 13, and a second joint pipe (not shown) is connected to the second port 13 by screwing onto this female thread.

[0018] A partition wall 14 extending along the axis α of the main body 11 is disposed inside the main body 11. The partition wall 14 extends in the transverse direction X inside the main body 11 and is supported by a left vertical wall 15 extending from its left end (X1) on the left side to the inner wall of the upper side (L1) of the main body 11 and a right vertical wall 16 extending from its right end (X2) on the right side to the inner wall of the lower side (L2) of the main body 11. This configuration divides the interior of the main body 11 into a first flow path 17 communicating with the first port 12 and a second flow path 18 communicating with the second port 13. A first stopper 17a protruding inward is formed on the inner wall of the first flow path 17. A second stopper 18a protruding inward is formed on the inner wall of the second flow path 18. As shown in FIG. 2 (only the second stopper 18a is shown in FIG. 2), the first stopper 17a and the second stopper 18a are formed in a generally rectangular shape when viewed from the side.

[0019] The first stopper 17a and the second stopper 18a are capable of contacting the tip of the second coupling pipe (or the first coupling pipe) when connecting the second port 13 (or the first port 12) to each coupling pipe, thereby limiting the degree to which each coupling pipe is tightened. This prevents the coupling pipes from being overtightened. As shown in FIG. 1 , a valve port 19 is formed in the center of the partition wall 14, penetrating the partition wall 14 in the axial direction L and connecting the first flow path 17 and the second flow path 18. A valve seat 20 is formed on the edge of the upper side L1 of the valve port 19, protruding toward the upper side L1 along its entire periphery. The upper surface of the valve seat 20 is formed in an arc shape convex toward the upper side L1, and its apex forms an abutment 21 that abuts against the lower surface of the valve disc 64. That is, the valve seat 20 is provided with the abutment 21 that surrounds the valve port 19 and is capable of abutting against the valve disc 64. When the valve body 64 abuts against the abutment portion 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 is open and the valve port 19 is open, the fluid flows in the order of the first flow path 17, the valve port 19, and the second flow path 18.

[0020] A substantially circular first opening 22 (opening) penetrating in the axial direction L is formed in the wall surface of the lower side L2 of the main body 11 at a position facing the valve port 19. A first diaphragm 23 (sealing member) that closes the first opening 22 is installed on the lower surface 11a of the wall surface of the lower side L2 of the main body 11. The first diaphragm 23 is formed in a plate shape using a resin material that is elastically deformable in the axial direction L, and maintains airtightness inside the main body 11 by sealing the first opening 22. A hole 23a penetrating in the axial direction L is formed in the center of the first diaphragm 23. A lower L2 portion (a portion located in the first flow path 17 of the second screw feed member 84) of a shaft portion 94 of a valve stem screw 90 (described later) is inserted and fixed in the axial direction L into the hole 23a. This allows the first diaphragm 23 to deform in the axial direction L in accordance with the displacement of the valve stem screw 90 and the valve disc 64 in the axial direction L. A first pressing member 30 is disposed on the lower side L2 of the first diaphragm 23. The first pressing member 30 is a member that presses the first diaphragm 23 against the lower surface 11a of the main body 11, and has the function of stably maintaining the state in which the first diaphragm 23 is fixed to the main body 11.

[0021] As shown in FIG. 3 , the first holding member 30 includes an upper wall portion 31 having a generally rectangular plate shape. Circular mounting holes 31a are formed in the four corners of the upper surface of the upper wall portion 31, penetrating the upper wall portion 31 in the plate thickness direction. Set screws 31b (see FIG. 4A ) are inserted into the mounting holes 31a. Side wall portions 32 are formed on the outer edge of the upper wall portion 31, bending in an L shape and extending downward L2. As shown in FIG. 4A , the surface of the side wall portion 32 facing inward in the transverse direction X faces a cap 40 (described later) in the transverse direction X, allowing the cap 40 to be guided in the axis L direction. That is, the side wall portions 32 function as a guide for the cap 40. Furthermore, the formation of the side wall portions 32 makes it difficult for the upper wall portion 31 to deform in the plate thickness direction. Therefore, the side wall portions 32 also function as reinforcing portions of the first holding member 30. This configuration suppresses deformation of the upper wall portion 31 when the set screw 31b is tightened, thereby suppressing deformation of the cap 40 in the direction of the axis L. As shown in Fig. 3, a ridge portion 32a formed in a convex arc shape on the lower side L2 is formed on the lower edge of each side wall portion 32. The ridge portion 32a is a portion for distinguishing the first pressing member 30 of this embodiment from a similar product of the first pressing member 30 used in a device other than the valve device 1 of this embodiment.

[0022] The formation of the ridges 32a prevents the first retainer member 30 from being accidentally installed if another part gets mixed in when the first retainer member 30 is installed. A circular opening 33 is formed in the center of the upper wall 31. A first retainer 34 (retainer) having a predetermined radial width is formed around the periphery of the opening 33. The first retainer 34 extends around the axis L (around the axis) along the periphery of the first opening 22. The first retainer 34 is formed in a convex arc shape on an upper side L1, with its radial center portion serving as a vertex 35 (shown by a dashed line in FIG. 3). As shown in FIG. 4(A), when the setscrew 31b is tightened, the upper surface of the first retainer 34 abuts against the lower surface of the first diaphragm 23 while the vertex 35 is engaged with the first diaphragm 23. The upper surface of the first retainer 34 is pressed against the lower surface of the first diaphragm 23 on the upper side L1. As a result, the first diaphragm 23 is pressed against the periphery of the first opening 22 .

[0023] The first diaphragm 23 is deformable in the direction of the axis L at a portion radially inward of the inner edge of the first pressing portion 34, and the inner edge of the first pressing portion 34 defines the deformable region of the first diaphragm 23. In this embodiment, the deformable region of the first diaphragm 23 is particularly referred to as the deformable portion 23b, and the surface of the upper side L1 of the deformable portion 23b is referred to as the pressure-receiving surface 23c (see FIG. 4(A)). The pressure-receiving surface 23c faces the valve port 19 and the valve disc 64 in the direction of the axis L, and a portion of the pressure-receiving surface 23c is capable of contacting the fluid. The pressure-receiving surface 23c is configured as a surface that receives fluid pressure toward the lower side L2 (the proximal side in the direction of the axis L, in which the valve disc 64 approaches the valve port 19). The entire pressure-receiving surface 23c may be configured to contact the fluid. The outer end 23c1, which is the radially outer end of the pressure-receiving surface 23c, is located at the same position as the inner edge of the first pressing portion 34 in the direction of the axis L. That is, the outer end 23c1 of the pressure-receiving surface 23c corresponds to the inner edge of the first pressing portion 34 in the axial direction L.

[0024] The position of an inner end 23c2, which is the radially inward end of the pressure-receiving surface 23c, is the same as the position of the outer peripheral surface of a valve stem member 60 (second feed screw member 84) described later in the axial direction L. That is, the pressure-receiving surface 23c extends in the radial direction of the second feed screw member 84 from the outer end 23c1 (a portion corresponding to the inner edge of the first presser portion 34 in the axial direction L) to the inner end 23c2 (the outer peripheral surface of the second feed screw member 84). As shown in FIG. 3 , an inclined portion 36 is formed on the inner edge of the first presser portion 34, extending downwardly L2 while reducing in diameter. A disk-shaped bottom wall portion 37 is formed on the lower end of the inclined portion 36 and extending in the transverse direction X. The formation of the inclined portion 36 and the bottom wall portion 37 creates a gap in the axial direction L between the first presser member 30 and the center of the first diaphragm 23, and this gap provides an allowance for deformation of the first diaphragm 23 downwardly L2. A hexagonal fixing hole 38 is formed in the center of the bottom wall portion 37 and penetrates in the direction of the axis L.

[0025] As shown in FIG. 4A, a hexagonal prism-shaped boss 39 is inserted into the fixing hole 38 and is movable in the axial direction L. The upper end surface of the boss 39 abuts against the lower surface of the first diaphragm 23, supporting the first diaphragm 23 from the lower side L2. A first through hole 39a penetrating in the axial direction L and a second through hole 39b communicating with the first through hole 39a are formed in the center of the boss 39. The first through hole 39a opens to the upper side L1. The second through hole 39b is continuous with the lower side L2 of the first through hole 39a, has a larger diameter than the first through hole 39a, and opens to the lower side L2. A step 39c whose diameter increases in the transverse direction X is formed at the boundary between the first through hole 39a and the second through hole 39b. A cap 40 for holding the first holding member 30 is installed on the lower side L2 of the first holding member 30.

[0026] The cap 40 includes a flange portion 41 that abuts against the lower surface of the first pressing portion 34 of the first pressing member 30, a sloped wall portion 42 that extends downward (L2) while reducing in diameter from the inner end of the flange portion 41, and a disk-shaped bottom plate portion 43 that extends from the lower end of the sloped wall portion 42 in the transverse direction X. The sloped wall portion 42 and the bottom plate portion 43 cover the sloped portion 36 and bottom wall portion 37 of the first pressing member 30. A hole (not shown) that penetrates the flange portion 41 in the axial direction L is formed, and the aforementioned set screw 31b is inserted into this hole. When the set screw 31b is tightened, the upper surface of the flange portion 41 presses the lower surface of the first pressing portion 34 toward the upper side L1. As a result, the first diaphragm 23 is sandwiched between the upper surface of the flange portion 41 and the lower surface 11a of the main body 11.

[0027] As shown in FIG. 1 , a circular second opening 24 is formed in the wall surface of the upper side L1 of the main body 11 at a position facing the valve port 19 and penetrating in the axial direction L. A second diaphragm 25 that closes the second opening 24 is installed on the upper surface 11b of the wall surface of the upper side L1 of the main body 11. The second diaphragm 25 is formed in a plate shape using a resin material that is elastically deformable in the axial direction L. By sealing the second opening 24, it maintains airtightness inside the main body 11. A second hole 25a that penetrates in the axial direction L is formed in the center of the second diaphragm 25, and a valve stem screw 90 is inserted into the second hole 25a in the axial direction L. A second holding member 50 is disposed on the upper side L1 of the second diaphragm 25. The second holding member 50 is formed in a cylindrical shape with a bottom that opens to the upper side L1. A lower plate portion 51 that forms the bottom of the second holding member 50 is formed with a protrusion 52 that protrudes to the lower side L2. The second pressing member 50 has a central portion formed with an inclined surface 53 that is inclined toward the upper side L1 as it approaches the center.

[0028] The inclined surface 53 forms a gap in the axial direction L between the second holding member 50 and the center of the second diaphragm 25, allowing the second diaphragm 25 to deform upward (L1). An insertion hole 54 is formed in the center of the second holding member 50, penetrating in the axial direction L. A sleeve 55 is installed at the edge of the insertion hole 54. The sleeve 55 is formed in a cylindrical shape extending in the axial direction L, and a second female threaded member 88 of the female threaded member 85 (described later) is inserted into the inside of the insertion hole 54. A recess 56 is formed in the outer peripheral surface of the sleeve 55, recessed radially inward. The recess 56 fits into the edge of the insertion hole 54. An annular pressure spring 57 is disposed around the entire inner surface of the recess 56. The pressure spring 57 presses the edge of the insertion hole 54 toward the lower side (L2). This secures the sleeve 55 to the second holding member 50.

[0029] A valve stem member 60 is installed inside the main body 11 configured as described above. The valve stem member 60 is a component that constitutes part of the second screw feed member 84, which will be described later, and is formed in a cylindrical shape that extends from the first flow path 17 to the second flow path 18 through the valve port 19. The lower end face of the valve stem member 60 abuts against the upper surface of the first diaphragm 23 at a position above the boss portion 39 on the upper side L1. As a result, the central portion of the first diaphragm 23 is sandwiched in the axial direction L between the lower end face of the valve stem member 60 and the upper end face of the boss portion 39. A protrusion 60a that protrudes toward the lower side L2 is formed on the lower surface of the valve stem member 60. The protrusion 60a bites into the upper surface of the first diaphragm 23, sealing the gap between the valve stem member 60 and the first diaphragm 23.

[0033] Note that the tip of this protrusion 60a may be considered to be the outer peripheral surface of the valve stem member 60 described above, and the same position as the position of the tip of this protrusion 60a may be considered to be the position of the inner end 23c2 of the pressure-receiving surface 23c. A central hole 61 with the axis L as its central axis is formed in the center of the valve stem member 60. A valve stem screw 90 is inserted into the central hole 61. A support protrusion 62 that protrudes radially outward is formed on the outer peripheral surface of the valve stem member 60. A cylindrical valve cover retainer 63 that surrounds the outer peripheral surface of the valve stem member 60 is installed on an upper side L1 of the support protrusion 62, spaced apart in the direction of the axis L. The upper end surface of the valve cover retainer 63 abuts against the lower surface of the second diaphragm 25, supporting the second diaphragm 25 from the lower side L2.

[0030] As shown in FIG. 4(B), an expanded diameter portion 63a that expands radially outward is formed at the lower end of the inner periphery of the valve cover retainer 63, and an O-ring 63b is installed in the expanded diameter portion 63a. A valve element 64 is fixed between the support protrusion 62 and the valve cover retainer 63. The valve element 64 is located on the upper side L1 of the valve port 19 (opposite the first opening 22) and is close to or separated from the valve port 19, and in this embodiment, is capable of seating on the valve seat portion 20. This allows the opening degree of the valve port 19 to be changed to 0 or more. The valve element 64 includes a valve element main body 65 that extends radially and surrounds the outer circumferential surface of the valve stem member 60.

[0031] The valve body 65 is formed in the shape of a thick disk. The upper surfaces of the support protrusions 62 of the valve stem member 60 abut against the lower surface of the valve body 65, thereby supporting the valve body 65 from the lower side L2. A valve cover 66 is attached to the upper side L1 of the valve body 65 and is integrated with the valve body 65. The valve cover 66 is formed by bending a metal plate made of stainless steel or the like, and covers the upper surface of the valve body 65, the upper corners of the valve body 65, and part of the side wall of the valve body 65. The upper surface of the valve cover 66 abuts against the lower end surface of the valve cover retainer 63 described above and also against the lower surface of the O-ring 63b. This forms the valve body 64 as a single unit with the valve stem member 60 and the valve cover retainer 63. The lower surface of the valve body 64 forms an opposing surface 67 that faces the valve port 19 and the pressure-receiving surface 23c of the first diaphragm 23 in the axial direction L. A portion of the opposing surface 67 is capable of coming into contact with the fluid, and is configured as a surface that receives fluid pressure toward the upper side L1 (the side away from the axis L in the direction in which the valve body 64 moves away from the valve port 19). Note that the entire opposing surface 67 may be configured to be capable of coming into contact with the fluid.

[0032] An outer end 67a, which is the radially outer end of the opposing surface 67 (in this embodiment, it is the outer end of the valve cover 66, but it may be the outer end of the valve body main body 65), is the radially outer end of the valve body 64. The position of an inner end 67b, which is the radially inner end of the opposing surface 67, is the same as the position of the outer peripheral surface of the valve stem member 60 (second feed screw member 84) in the axial direction L. That is, the opposing surface 67 extends in the radial direction of the second feed screw member 84 from the outer end 67a (the radially outer end of the valve body 64) to the inner end 67b (the outer peripheral surface of the second feed screw member 84). Note that in this embodiment, the position of the inner end 67b of the opposing surface 67 is the position of the outer peripheral surface of the valve stem member 60 in the axial direction L, but is not limited thereto. The position of the inner end 67b of the opposing surface 67 in the axial direction L may be the position of the inner peripheral surface of the O-ring 63b described above that surrounds the valve stem member 60 in the axial direction L. Here, the inner end portion 23c2 of the pressure-receiving surface 23c shown in Figure 4(A) and the inner end portion 67b of the opposing surface 67 shown in Figure 4(B) are located at the same position in the axial direction L (i.e., the same position as the position of the outer peripheral surface of the valve rod member 60).

[0033] In the direction of axis L, the outer end 23c1 of the pressure-receiving surface 23c shown in Fig. 4(A) (the portion corresponding to the inner edge of the first pressing portion 34 in the direction of axis L) is located radially outward from the outer end 67a of the opposing surface 67 (the outer end of the valve cover 66 or the outer end of the valve body main body 65) shown in Fig. 4(B). As a result, the width dimension W1 from the outer end 23c1 to the inner end 23c2 of the pressure-receiving surface 23c is larger than the width dimension W2 from the outer end 67a to the inner end 67b of the opposing surface 67 shown in Fig. 4(B). The area of ​​the pressure-receiving surface 23c is larger than the area of ​​the opposing surface 67.

[0034] Next, the drive unit 70 will be described. The drive unit 70 drives the valve element 64 in the direction of the axis L. As shown in FIG. 1, the drive unit 70 includes a housing 71 disposed on the upper side L1 of the main body 11 and an actuator unit 77 disposed on the upper side L1 of the housing 71. The housing 71 is box-shaped and includes a top wall 72 extending in the transverse direction X and a cover wall portion 73 extending from the edge of the top wall 72 to the lower side L2. A large-diameter hole 72a and a small-diameter hole 72b are formed in this order from the upper side L1 through the center of the top wall 72 in the direction of the axis L. The large-diameter hole 72a opens to the upper side L1. The small-diameter hole 72b is coaxial with the large-diameter hole 72a and has a smaller diameter than the large-diameter hole 72a. A pair of guide portions 72c extending to the lower side L2 are formed in the center of the lower surface of the top wall 72. The guide portions 72c are formed in plate shapes and arranged at intervals in the transverse direction X so as to sandwich the axis L. The surfaces of the guide portions 72c facing inward in the transverse direction X form guide surfaces 72c1 that extend in the direction of the axis L and face each other. A first female screw member 86, which will be described later, is arranged in the space sandwiched between the pair of guide surfaces 72c1 in the left-right direction X.

[0035] The cover wall portion 73 is formed in a plate shape and extends downward L2 from each of the left edge X1, right edge X2, front edge, and rear edge of the top wall 72. The lower end of the cover wall portion 73 abuts against the upper surface of the lower plate portion 51 of the second pressing member 50 described above.

[0036] A collar 74 extending in the direction of axis L is provided inside the housing 71. The collar 74 is provided at a corner inside the housing 71 formed by connecting the cover wall portions 73, and extends in the direction of axis L. A setscrew 76 (described below) is inserted through the collar 74, and functions as a reinforcing member that suppresses deformation of the housing 71 due to stress generated when the setscrew 76 is tightened. A bracket 75 having a substantially rectangular plate shape is provided on the top surface of the housing 71. A through-hole 75a penetrating in the direction of axis L is formed in the center of the bracket 75. Furthermore, through-holes (not shown) are formed in the four corners of the top surface of the bracket 75, and the setscrews 76 are inserted through the through-holes.

[0037] The setscrew 76 is a screw that connects the bracket 75, housing 71, second holding member 50, second diaphragm 25, and main body 11 together. It extends through the collar 74 in the direction of axis L and is fixed to the upper surface 11b of the main body 11. Tightening the setscrew 76 integrates the setscrew 76, bracket 75, housing 71, second holding member 50, second diaphragm 25, and main body 11. At this time, the force generated by tightening the setscrew 76 can also be borne by the collar 74, thereby suppressing deformation of the housing 71. At this time, the lower plate portion 51 of the second holding member 50 abuts against the upper surface of the second diaphragm 25 with the protrusion 52 biting into the upper surface of the second diaphragm 25. The lower plate portion 51 of the second holding member 50 is pressed against the lower side L2 against the upper surface of the second diaphragm 25.

[0038] As a result, the second diaphragm 25 is pressed against the periphery of the second opening 24. An actuator unit 77 is installed on the upper side L1 of the housing 71. The actuator unit 77 is a part that applies a rotational force as a driving force to the screw feed mechanism 80, and is configured by, for example, a stepping motor. As shown in FIG. 2, the actuator unit 77 has a box-shaped case 77a that houses a stator coil (not shown) and the like, and is fixed to the bracket 75 by a set screw 78. A pulse is applied to the actuator unit 77 via lead wires 79 extending inside and outside the case 77a, which rotates a spindle 81 (described below).

[0039] Next, the screw feed mechanism 80 will be described. As shown in FIG. 1, the screw feed mechanism 80 is a mechanism that transmits the driving force of the drive unit 70 to the valve body 64, and includes a spindle 81 (first screw feed member) and a second screw feed member 84, each of which is made of a metal material such as stainless steel and extends in the direction of axis L. The upper end of the spindle 81 is inserted into a through-hole 75a of the bracket 75, extends in the direction of axis L, and is connected to the actuator unit 77. An enlarged diameter portion 81a, which has a diameter larger than that of the other portions of the spindle 81, is formed in an upper side L1 portion of the spindle 81. The enlarged diameter portion 81a is positioned 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 axis L. Annular thrust washers 82 are respectively disposed on the upper and lower surfaces of the enlarged diameter portion 81a.

[0040] The upper surface of the upper-side L1 thrust washer 82 abuts against the lower surface of the bracket 75, thereby restricting displacement of the upper-side L1 thrust washer 82 toward the upper side L1. The lower surface of the lower-side L2 thrust washer 82 abuts against the lower surface of the large-diameter hole 72a, thereby restricting displacement of the lower-side L2 thrust washer 82 toward the lower side L2. With this configuration, when the actuator unit 77 is driven, the spindle 81 rotates about the axis L while its displacement in the direction of the axis L is restricted. A male thread 83 is formed on the outer peripheral surface of the lower-side L2 portion of the spindle 81. The second screw feed member 84 is a member that can be displaced in the direction of the axis L by receiving the rotational force of the spindle 81, and includes a female thread member 85, a valve stem screw 90, and the valve stem member 60 described above. The female thread member 85 includes a first female thread member 86 that constitutes the upper L1 portion, a second female thread member 88 that constitutes the lower L2 portion, and a connecting member 89 that connects the first female thread member 86 and the second female thread member 88.

[0041] As shown in FIG. 5, the first female thread member 86 is disposed in a space sandwiched in the transverse direction X by the guide surfaces 72c1 of the guide portion 72c of the housing 71. The first female thread member 86 has an outer portion 86a formed of a metal material in a cylindrical shape extending in the direction of the axis L. A guided surface 86a2 constituted by a flat surface extending in the direction of the axis L is formed in a portion of the outer portion 86a. The guided surface 86a2 is formed by, for example, cutting, in the direction of the axis L, a portion of the outer portion 86a's arc-shaped outer peripheral surface 86a1 (before machining), which is shown by imaginary lines. The guided surface 86a2 is slidable relative to the guide surfaces 72c1 of the guide portion 72c. This sliding prevents the first female thread member 86 from rotating about the axis L but allows it to move back and forth in the direction of the axis L.

[0042] A resin inner cylindrical portion 86b is disposed on the inner circumferential surface of the outer portion 86a. The inner cylindrical portion 86b is formed integrally with the outer portion 86a by insert molding. A helical groove 86c extending around the axis L is formed in the outer portion 86a at the boundary with the inner cylindrical portion 86b. The formation of the helical groove 86c prevents the outer portion 86a and the inner cylindrical portion 86b from rotating relative to each other around the axis L during insert molding. Furthermore, in this configuration, the contact area between the inner cylindrical portion 86b and the outer portion 86a is larger than in a configuration without the helical groove 86c, thereby preventing the inner cylindrical portion 86b from falling off. A female thread 86d is formed on the inner circumferential surface of the inner cylindrical portion 86b. The female thread 86d is threadedly engaged with the male thread 83 of the spindle 81. This threaded engagement connects the spindle 81 to the second screw feed member 84. When the spindle 81 rotates around the axis L, the female screw 86d is threaded, and the female screw member 85 moves in the direction of the axis L while its rotation around the axis L is restricted.

[0043] A first flange portion 87 extending radially outward is formed at the lower end of the outer portion 86a. A pin hole 87a opening to the lower side L2 is formed in the lower surface of the first flange portion 87. The pin hole 87a is a hole for inserting a pin (not shown) provided in a mold during insert molding of the inner cylindrical portion 86b, and functions as a positioning hole to prevent displacement of the outer portion 86a during insert molding. The second female threaded member 88 is formed of a metal material and has a cylindrical shape extending in the direction of the axis L. A second flange portion 88a extending radially outward is formed at the upper end of the second female threaded member 88. The second flange portion 88a has a larger diameter than the first flange portion 87 of the first female threaded member 86, and its upper surface abuts against the lower surface of the first flange portion 87. As shown in FIG. 1, a portion L2 of the second female threaded member 88 below the second flange portion 88a is inserted into the center portion of the sleeve 55 described above. The second female thread member 88 has a connecting female thread 88b formed in the center thereof.

[0044] As shown in FIG. 5 , the connecting member 89 is formed in a generally L-shape in a cross section along the axis L so as to cover the upper surface and side surfaces of the first flange portion 87 and a portion of the upper surface of the second flange portion 88a. A side wall 89a of the connecting member 89 is disposed at a distance from the first flange portion 87 in the transverse direction X and extends in the transverse direction L. A lower end of the side wall 89a is connected to the upper surface of the second flange portion 88a by welding or the like. An upper wall 89b of the connecting member 89 extends inward in the transverse direction X from the upper end of the side wall 89a. The upper wall 89b is disposed at a distance from the first flange portion 87 of the first female threaded member 86 in the axial L direction and at a distance from the outer portion 86a of the first female threaded member 86 in the transverse direction X. With this configuration, the second female threaded member 88 and the connecting member 89 are connected to the first female threaded member 86 with play in the axial L direction and the transverse direction X.

[0045] This connection allows the second female threaded member 88 to be displaced in the axial direction L and the transverse direction X relative to the first female threaded member 86. Therefore, the valve disc 64, which is integrated with the second female threaded member 88 via the valve stem screw 90 (described later), can be displaced in the axial direction L and the transverse direction X. In other words, the valve disc 64 is adjustable in the axial direction L and the transverse direction X. Therefore, even if the spindle 81 and the valve stem screw 90 are misaligned, for example, the adjustment can absorb the misalignment, preventing the drive unit 70 from locking and reducing the load on the drive unit 70. Furthermore, absorbing the misalignment through the adjustment can prevent tilting of the valve disc 64, thereby maintaining stable sealing performance of the valve disc 64.

[0046] 1, the valve stem screw 90 is a screw that connects the boss portion 39, first diaphragm 23, valve stem member 60, valve body 64, valve cover retainer 63, and second diaphragm 25, in that order from the lower side L2, into a single unit, and connects these together to the second female threaded member 88. A head portion 91 of the valve stem screw 90 is disposed within the second through-hole 39b of the boss portion 39. A spring washer 92 and a plain washer 93 are disposed between the upper surface of the head portion 91 and the lower surface of the step portion 39c of the boss portion 39.

[0047] A shaft 94 extending toward the upper side L1 is formed at the center of the head 91. The shaft 94 passes through the first through-hole 39a of the boss 39, the hole 23a of the first diaphragm 23, the center hole 61 of the valve stem member 60, and the second hole 25a of the second diaphragm 25, and extends to the upper side L1 of the second diaphragm 25. A connecting male thread 95 is formed on the outer circumferential surface of the shaft 94 in a portion L1 above the second diaphragm 25. The connecting male thread 95 is threadedly engaged with the connecting female thread 88b of the second female thread member 88, thereby forming the second female thread member 88, the boss 39, the first diaphragm 23, the valve stem member 60, the valve disc 64, the valve cover retainer 63, the second diaphragm 25, and the valve stem screw 90 into a single unit. The connecting male thread 95 may be formed on the entire outer circumferential surface of the shaft portion 94, not limited to the portion L1 above the second diaphragm 25.

[0048] Next, the operation of the valve device 1 will be described. In this valve device 1, the pressures in the housing 71, the first pressing member 30, and the cap 40 are equal to atmospheric pressure. The fluid flowing from the first flow path 17 to the second flow path 18 causes the pressures in the first flow path 17 and the second flow path 18 to be greater than atmospheric pressure. As shown in FIG. 1 , when the valve element 64 is seated on the valve seat 20, the valve port 19 is closed, and the flow of the higher-pressure fluid from the first flow path 17 to the second flow path 18 is stopped. From this state, when a pulse is applied to the actuator unit 77, the spindle 81 rotates about the axis L while its displacement in the direction of the axis L is restricted. The rotation of the spindle 81 feeds the female thread 86d that is threaded onto the male thread 83, displacing the first female thread member 86 toward the upper side L1.

[0049] As a result, the second female threaded member 88, which is connected to the first female threaded member 86 with play in the axial direction L and the transverse direction X as described above, and the boss portion 39, first diaphragm 23, valve stem member 60, valve disc 64, valve cover retainer 63, second diaphragm 25, and valve stem screw 90, which are integral with the second female threaded member 88, are displaced upward (L1). At this time, the central portions of the first diaphragm 23 and second diaphragm 25 are deformed upward (L1). Due to these displacements and deformations, the valve disc 64 gradually rises, gradually opening the valve port 19. Next, the spindle 81 is rotated in the reverse direction by applying the pulse. As a result, the first female threaded member 86, second female threaded member 88, boss portion 39, first diaphragm 23, valve stem member 60, valve disc 64, valve cover retainer 63, second diaphragm 25, and valve stem screw 90 are displaced downward (L2) by the screw feed. Then, the central portions of the first diaphragm 23 and the second diaphragm 25 are deformed downward L2, causing the valve element 64 to gradually descend and close.

[0050] In this embodiment, the second female threaded member 88, which is connected to the first female threaded member 86 with backlash as described above, and the boss portion 39, first diaphragm 23, valve stem member 60, valve element 64, valve cover retainer 63, second diaphragm 25, and valve stem screw 90 are integrally connected (integrated). Therefore, the displacement of the valve element 64 and each component integrally connected to the valve element 64 in the direction of axis L is linked to the deformation of the first diaphragm 23. In this configuration, as shown in FIGS. 4(A) and 4(B), the area of ​​the pressure-receiving surface 23c is larger than the area of ​​the opposing surface 67. Therefore, the balance between the force applied to the pressure-receiving surface 23c by the fluid pressure and the force applied to the opposing surface 67 by the fluid pressure is disrupted. This makes the force with which the fluid urges the valve body 64 toward the lower side L2 (the above-mentioned close side) via the pressure-receiving surface 23c greater than the force with which the fluid urges the valve body 64 toward the upper side L1 (the above-mentioned separated side) via the opposing surface 67, and the force that causes the valve body 64 to float toward the separated side can be almost canceled out.

[0051] This biases the valve element 64 downward (L2), and also biases the second female thread member 88, which is integrally connected to the valve element 64, downward (L2). This allows the valve element 64 to be pressed toward the valve port 19, allowing the drive unit 70 to be operated with reduced backlash in the axial direction (L), such as backlash between the male thread 83 of the spindle 81 and the female thread 86d of the female thread member 85, backlash between the first flange portion 87 of the first female thread member 86 and the connecting member 89, and other backlash. This reduces the unintended lift of the valve element 64, thereby preventing unintended valve opening and hysteresis caused by a phenomenon that makes it difficult to close the valve. Furthermore, in this embodiment, as described above, 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 port 19 is open, a jet of fluid may be generated, spraying upward from the first flow path 17 to the second flow path 18. However, with this configuration, the valve can be opened with the valve element 64 pressed toward the valve port 19 and with play in the axial direction L, such as play in the screw feed mechanism 80, reduced, so that the valve element 64 can be prevented from unintentionally rising up by the amount of play in the axial direction L. This also makes it possible to stabilize the behavior of the valve element 64 immediately before and after the valve is opened.

[0052] Note that if the area of ​​the pressure-receiving surface 23c is made too large, the driving force required to displace the valve element 64 in the separating direction becomes too large. Therefore, it is preferable to set the area of ​​the pressure-receiving surface 23c to be greater than 1.0 times the area of ​​the opposing surface 67 but not greater than 4.0 times the area of ​​the opposing surface 67. By making the area of ​​the pressure-receiving surface 23c greater than 1.0 times the area of ​​the opposing surface 67, the following can be achieved. That is, the force with which the fluid urges the valve element 64 toward the lower side L2 via the pressure-receiving surface 23c can be made greater than the force with which the fluid urges the valve element 64 toward the upper side L1 via the opposing surface 67, thereby preferably suppressing lifting of the valve element 64. Furthermore, by setting the area of ​​the pressure-receiving surface 23c to be not greater than 4.0 times the area of ​​the opposing surface 67, it is possible to prevent the force with which the fluid urges the valve element 64 toward the lower side L2 via the pressure-receiving surface 23c from becoming too large.

[0053] Next, the flow rate characteristics of the valve device 1 will be described. FIG. 6 is a graph showing the flow rate characteristics of the valve device 1. The flow rate characteristics are values ​​expressed as the flow rate of the fluid passing through the valve port 19 relative to the amount of operation of the spindle 81 (i.e., the amount of operation of the drive unit 70), and FIG. 6 shows changes in this flow rate characteristic for each amount of operation. In the graph shown in FIG. 6, the horizontal axis represents the amount of operation of the spindle 81 in the valve opening direction, and the vertical axis represents the flow rate of the fluid passing through the valve port 19. As shown by the solid line graph in FIG. 6, the flow rate characteristics include an opening direction characteristic A1 that indicates changes in the flow rate characteristics when the valve is open, and a closing direction characteristic A2 that indicates changes in the flow rate characteristics when the valve is closed. Here, the opening direction characteristic A1 and the closing direction characteristic A2 do not completely match. This is because the movement of the valve body 64 in the valve opening direction coincides with the direction of fluid flow from the first flow path 17 to the second flow path 18, while the movement of the valve body 64 in the valve closing direction coincides with the direction of fluid flow, and therefore the valve body 64 is relatively prone to displacement in the valve opening direction but is difficult to displace in the valve closing direction.

[0054] In this 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 difficulty in closing the valve. Hysteresis H1 in this embodiment is significantly smaller than the conventional hysteresis H2, which is generated by the closing direction characteristic a2 in a conventional valve device, as shown by the dotted line in FIG. 6 . This is because, as described above, the balance between the force applied to the pressure-receiving surface 23c by the fluid pressure and the force applied to the opposing surface 67 by the fluid pressure is disrupted. That is, the force with which the fluid urges the valve disc 64 toward the lower side L2 (the proximal side) via the pressure-receiving surface 23c is greater than the force with which the fluid urges the valve disc 64 toward the upper side L1 (the distal side) via the opposing surface 67, thereby substantially canceling the force that tends to lift the valve disc 64 toward the distal side. This significantly reduces hysteresis H1 compared to hysteresis H2.

[0055] As described above, according to the embodiment described above, the second screw feed member 84 and the valve body 64 are integrally connected (integrated), and the second screw feed member 84 and the first diaphragm 23 (sealing member) are integrally connected (integrated), so that the displacement of the second screw feed member 84 and the valve body 64 in the direction of the axis L and the deformation of the first diaphragm 23 in the direction of the axis L are linked. Furthermore, in this configuration, the area of ​​the pressure-receiving surface 23c of the first diaphragm 23 is larger than the area of ​​the opposing surface 67 of the valve body 64, so that it is possible to disrupt the balance between the force applied to the pressure-receiving surface 23c by the fluid pressure and the force applied to the opposing surface 67 by the fluid pressure. This makes it possible to make the force with which the fluid urges the valve disc 64 toward the lower side L2 (toward the valve port 19 (near side)) via the pressure-receiving surface 23c greater than the force with which the fluid urges the valve disc 64 toward the upper side L1 (opposite the valve port 19 (away side)) via the opposing surface 67, thereby canceling the force that tends to lift the valve disc 64 toward the away side. Therefore, the valve port 19 can be opened and closed in a state where the valve disc 64 is pressed toward the valve port 19 and play in the axial direction L, such as play in the screw feed mechanism 80, is reduced. Therefore, it is possible to prevent unintended lifting of the valve disc 64, suppress unintended valve opening and the occurrence of hysteresis H1, and provide a valve device 1 that can stably control the flow rate of the fluid.

[0056] Furthermore, according to the above embodiment, the pressure-receiving surface 23c is configured as a surface that receives fluid pressure toward the downward side L2, and the opposing surface 67 is configured as a surface that receives fluid pressure toward the upward side L1. With this configuration, the pressure-receiving surface 23c that receives fluid pressure toward the proximal side in the direction of the axis L is made larger than the opposing surface 67 that receives fluid pressure toward the distal side in the direction of the axis L, and the force with which the fluid urges the valve disc 64 toward the valve port 19 via the pressure-receiving surface 23c can be made larger than the force with which the fluid urges the valve disc 64 toward the opposite side from the valve port 19 via the opposing surface 67.

[0057] Furthermore, according to the above embodiment, the pressure-receiving surface 23c extending from the outer end 23c1 (the portion corresponding to the inner edge of the first pressing portion 34) to the inner end 23c2 (the outer peripheral surface of the second screw feed member 84) is made larger than the opposing surface 67 extending from the outer end 67a (the radial outer end of the valve body 64) to the inner end 67b (the outer peripheral surface of the second screw feed member 84), and the force with which the fluid urges the valve body 64 toward the valve port 19 via the pressure-receiving surface 23c can be made larger than the force with which the fluid urges the valve body 64 toward the opposite side of the valve port 19 via the opposing surface 67.

[0058] Furthermore, according to the above embodiment, the valve device 1 in which a jet of fluid is generated from the first flow path 17 to the second flow path 18 when the valve port 19 is open can be configured as follows: That is, the valve can be opened in a state in which the valve element 64 is pressed toward the valve port 19 and play in the axial direction L, such as play in the screw feed mechanism 80, is reduced, thereby preventing the valve element 64 from unintentionally rising up by the amount of play in the axial direction L. This stabilizes the behavior of the valve element 64 immediately before and after the valve is opened.

[0059] Furthermore, according to the above embodiment, by making the area of ​​the pressure-receiving surface 23c greater than 1.0 times the area of ​​the opposing surface 67, the force with which the fluid urges the valve element 64 toward the lower side L2 via the pressure-receiving surface 23c can be made greater than the force with which the fluid urges the valve element 64 toward the upper side L1 via the opposing surface 67, thereby preferably suppressing lifting of the valve element 64. Furthermore, by making the area of ​​the pressure-receiving surface 23c 4.0 times or less the area of ​​the opposing surface 67, the force with which the fluid urges the valve element 64 toward the lower side L2 via the pressure-receiving surface 23c can be prevented from becoming too large. Therefore, the driving force of the drive unit 70 that drives the valve element 64 can be prevented from becoming too large, allowing the valve element 64 to be driven smoothly.

[0060] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention.

[0061] For example, in this embodiment, the position of the inner end 23c2 of the pressure-receiving surface 23c is the same as the position of the outer circumferential surface of the valve stem member 60 in the direction of the axis L. However, this is not limited to this, and as described above, the position of the inner end 23c2 may be the same as the position of the tip of the protrusion 60a on the underside of the valve stem member 60 in the direction of the axis L. Also, in this embodiment, the position of the inner end 67b of the opposing surface 67 is the same as the position of the outer circumferential surface of the valve stem member 60 in the direction of the axis L. However, this is not limited to this, and as described above, the position of the inner circumferential surface of the O-ring 63b surrounding the valve stem member 60 may be the position of the inner end 67b in the direction of the axis L.

[0062] Furthermore, the position of the outer end 67a of the opposing surface 67 may be the same as the position of the abutting portion 21 of the valve seat 20 in the direction of the axis L, for example. That is, the opposing surface 67 may extend in the radial direction of the second feed screw member 84 from the outer end 67a (the portion corresponding to the abutting portion 21 in the direction of the axis L) to the inner end 67b (the outer peripheral surface of the second feed screw member 84). With this configuration, particularly when the valve is closed, the force with which the high-pressure fluid in the first flow path 17 urges the valve disc 64 toward the valve port 19 via the pressure-receiving surface 23c can be made larger than the force with which the high-pressure fluid in the first flow path 17 urges the valve disc 64 toward the opposite side of the valve port 19 via the opposing surface 67. Therefore, when the valve port 19 is closed, the valve can be opened with the valve disc 64 pressed toward the valve port 19 and no backlash in the direction of the axis L is present. Therefore, it is possible to prevent the valve element 64 from unintentionally rising up, and to prevent distortion of the opening direction characteristic A1 (fluid characteristic). [Explanation of symbols]

[0063] L axis 1 Valve gear 10 Valve body 17 First Channel 18 Second Channel 19 Valve port 22 First opening (opening) 23 First diaphragm (sealing member) 23c Pressure surface 67 Opposite Surface 64 Valve body 70 Drive unit 80 Screw feed mechanism 81 Spindle (first screw feed member) 84 Second screw feed member

Claims

1. A valve device comprising: a valve body having a valve port through which a fluid passes and an opening facing the valve port; a valve element that approaches or moves away from the valve port on the opposite side of the opening; a drive unit that drives the valve element; and a screw feed mechanism that transmits the drive force of the drive unit to the valve element, the screw feed mechanism includes a first screw feed member that rotates about an axis by the driving force, and a second screw feed member that is connected to the first screw feed member and is displaceable in an axial direction, the second screw feed member is integral with the valve body and extends from a second flow path in which the valve body is located through the valve port to a first flow path in which the opening is located; a sealing member that closes the opening and is deformable in the axial direction is provided at a portion of the second screw feed member that is located in the first flow path, the sealing member has a pressure-receiving surface that faces the valve port and the valve body and comes into contact with the fluid; the valve body includes an opposing surface that faces the valve port and the pressure-receiving surface, The valve device is characterized in that the area of ​​the pressure-receiving surface is larger than the area of ​​the opposing surface.

2. the pressure-receiving surface is a surface that receives fluid pressure toward a proximal side in the axial direction, which is a direction in which the valve element approaches the valve port, 2. The valve device according to claim 1, wherein the opposing surface is configured as a surface that receives fluid pressure toward a direction away from the valve port in the axial direction, which is a direction in which the valve body moves away from the valve port.

3. a pressing portion that presses the sealing member against the opening periphery of the opening, the pressure-receiving surface extends in a radial direction of the second screw feed member from a portion corresponding to an inner edge of the pressing portion in the axial direction to an outer peripheral surface of the second screw feed member, the valve body extends in the radial direction of the second screw feed member, The valve device according to claim 2, wherein the opposing surface extends in the radial direction from the radially outer end of the valve body to an outer peripheral surface of the second screw feed member.

4. 2. The valve device according to claim 1, wherein, in a valve-closed state where the valve port is closed by the valve body, the internal pressure of the first flow path is higher than the internal pressure of the second flow path.

5. 5. The valve device according to claim 1, wherein the area of ​​the pressure-receiving surface is greater than 1.0 times the area of ​​the opposing surface and is not greater than 4.0 times the area of ​​the opposing surface.

Images