Valve

Abstract

To provide a valve capable of preventing deterioration of sealing performance by suppressing deformation of a valve seat with a simple structure even under a high temperature environment.SOLUTION: The sealing load adjusting mechanism 50 includes an annular spring 60 in which a bulging surface 61 in which at least a central portion symmetrical with respect to a central shaft A bulges so as to apply a resilient force to the stem 32 in a direction opposite to the seat 33 in a state in which the stem 32 is moved to the valve-closed position is disposed so as to be capable of abutting on the stem 32, and an inner peripheral surface 60b portion is disposed outside an outer peripheral surface 70b portion of the annular spring 60. The annular spring 60 is elastically deformed so as to increase an elastic force that pushes back the stem 32 in a direction opposite to the valve seat 33 in accordance with an increase in an expansion amount of the annular thermal expanding member 70 toward the 60b along with a temperature rise.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a valve for controlling the flow of a fluid, and more particularly to a valve for controlling the flow of a high-temperature fluid by opening and closing a valve element by moving a stem toward and away from a valve seat. [Background technology]

[0002] In recent years, in semiconductor manufacturing processes, panel manufacturing processes, and the like, the temperature of fluids used in semiconductor manufacturing equipment has been increasing, and high-temperature fluids exceeding 200°C are now being used. Some valves used to control high-temperature fluids in this way use metal valve seats, but because these have inferior sealing properties compared to plastic valve seats, they sometimes use highly heat-resistant plastic valve seats. However, when a resin valve seat is used, the strength of the valve seat decreases due to the effects of heat, and the valve seat may be deformed by the load applied by the stem, which may result in adverse effects on sealing performance. For this reason, various valves have been proposed that can prevent deformation of the valve seat even when used in a high-temperature environment.

[0003] Patent document 1 describes a control valve in which a disc spring mechanism 14 interposed between the lower end of the piezoelectric element 13 and the diaphragm retainer 12 absorbs the extension of the piezoelectric element 13, and a repulsive force according to the amount of displacement of the disc spring 23 is applied to the seat portion (consisting of the valve seat 7c and the portion of the metal diaphragm 8 that contacts the valve seat 7c), and as a result, the large force generated by the piezoelectric element 13 is not applied directly to the seat portion, preventing damage to the metal diaphragm 8 and the valve seat 7c.

[0004] Furthermore, Patent Document 2 describes a control valve that includes an operating pressure adjusting device 5 that adjusts the operating air supplied from an operating air supply source 8 to a required operating pressure and supplies the adjusted pressure to an actuator 4, an inlet passage pressure sensor 6 provided on the inlet passage side of the valve body 2, and an outlet passage pressure sensor 7 provided on the outlet passage side of the valve body 2, and that adjusts the thrust acting between the valve seat and the valve element when the flow path is closed based on the pressure obtained by the inlet passage pressure sensor 6 and the pressure obtained by the outlet passage pressure sensor 7. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-192269 [Patent Document 2] Japanese Patent Publication No. 2020-20379 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the control valve described in Patent Document 1, when the valve is closed, the disc spring 23 deforms by a fixed amount in response to the thrust from the piezoelectric element 13, and a fixed repulsive force determined by this fixed deformation amount is obtained. For this reason, in the control valve described in Patent Document 1, the disc spring 23 is unable to obtain an appropriate repulsive force according to the temperature, and depending on the temperature, the repulsive force of the disc spring 23 may become excessive or insufficient, which may ultimately have an adverse effect on the sealing performance.

[0007] Furthermore, the control valve described in Patent Document 2 is equipped with an operating pressure adjusting device 5, an inlet passage side pressure sensor 6, and an outlet passage side pressure sensor 7 to adjust the thrust acting between the valve seat and the valve body when the flow path is closed, which poses a problem of a complex device configuration.

[0008] The present invention was developed to solve the problems of the past, and its purpose is to provide a valve that has a simple structure and is able to suppress deformation of the valve seat and prevent a decrease in sealing performance even in high-temperature environments. [Means for solving the problem]

[0009] In order to achieve the above object, the invention of claim 1 is a valve comprising: a stem that is arranged to be freely movable back and forth along the central axis, and that, when the valve is closed, moves toward the valve body, thereby applying a sealing load that abuts the valve body against the valve seat to seal; and a sealing load adjustment mechanism that adjusts the sealing load applied to the valve seat by the stem, wherein the sealing load adjustment mechanism comprises an annular spring that is arranged so that its bulging surface, at least its central portion bulging symmetrically with the central axis, can freely abut against the stem so as to apply a resilient force to the stem in the opposite direction to the valve body when the stem is moved to the valve closed position; and an annular thermal expansion member that is arranged with its inner peripheral surface facing outside the outer peripheral surface of the annular spring and that applies a force to the annular spring that presses the outer peripheral surface of the annular spring toward the center through thermal expansion, wherein the annular spring elastically deforms to increase the resilient force that pushes the stem in the opposite direction to the valve body as the annular thermal expansion member increases in expansion toward the center as the temperature rises.

[0010] The invention of claim 2 is a valve in which the seal load adjustment mechanism further has an annular support member that supports the outer surface of the annular spring so as to be able to press it toward the center, and when the amount of expansion of the annular thermal expansion member increases, it presses the annular spring toward the center via the annular support member.

[0011] The invention of claim 3 is a valve in which a first annular groove and a second annular groove are formed at the portion where the end faces abut and are connected in the central axial direction, so that the groove bottom surfaces face each other at the edges of the abutting end faces and so that the groove outer surfaces are connected flush, and an annular thermal expansion member is arranged between the first annular groove and the second annular groove and so that it abuts on the connected flush groove outer surfaces and the opposing groove bottom surfaces.

[0012] The invention according to claim 4 is a valve in which the annular support member is made of metal.

[0013] The invention according to claim 5 is a valve in which the annular thermal expansion member is made of perfluoroalkoxyalkane. [Effects of the Invention]

[0014] According to the invention of claim 1, the seal load adjustment mechanism comprises an annular spring having a bulging surface that is symmetrical about the central axis and bulges at least in the central portion so as to be able to freely abut against the stem when the stem is moved to the valve closed position, and an annular thermal expansion member that is arranged with its inner peripheral surface facing outward from the outer peripheral surface of the annular spring and that applies a force to the annular spring that presses the outer peripheral surface of the annular spring toward the center due to thermal expansion. As a result, the annular spring is elastically deformed by bending symmetrically about the central axis so as to increase the elastic force pushing the stem in the opposite direction to the valve body in response to an increase in the amount of expansion toward the center of the annular thermal expansion member that increases with increasing temperature. Therefore, by using an annular thermal expansion member and annular spring, the reaction force pushing the stem in the opposite direction to the valve body can be increased as the temperature rises, and as a result, deformation of the valve seat can be suppressed and a decrease in sealing performance can be prevented even in high-temperature environments, despite the simple configuration.

[0015] According to the invention of claim 2, the seal load adjustment mechanism further has an annular support member that supports the outer surface of the annular spring so as to be freely pressed toward the center, and when the amount of expansion of the annular thermal expansion member increases, it presses the annular spring toward the center via the annular support member. This allows the pressing force applied to the annular spring when the annular thermal expansion member expands to be more reliably applied to the annular spring by the annular support member as a force pressing the annular spring toward the center. Therefore, the annular spring can be elastically deformed more stably so that the elastic force of the annular spring that pushes back the stem in the direction away from the valve body increases in accordance with the amount of expansion of the annular thermal expansion member.

[0016] According to the invention of claim 3, in the portion where the end faces are connected by abutting each other in the central axis direction, a first annular groove and a second annular groove are formed at the edge portions of each abutting end face so that the groove bottom surfaces face each other and so that the groove outer peripheral surfaces are connected flush, and the annular thermal expansion member is arranged between the first annular groove and the second annular groove and so that it faces the connected flush groove outer peripheral surfaces and the opposing groove bottom surfaces. As a result, the annular thermal expansion member is arranged so as to close the connecting portion where the end faces of the annular members abut against each other from the inside of the first annular groove and the second annular groove. Therefore, the annular thermal expansion member seals the connected portion in the central axis direction, and the annular thermal expansion member expands thermally as the temperature rises, thereby further improving the sealing performance of the connected portion.

[0017] According to the invention of claim 4, since the annular support member is made of metal, the pressing force acting on the annular spring when the annular thermal expansion member expands can be more stably applied toward the center by the strong annular support member.

[0018] According to the invention of claim 5, the annular thermal expansion member is made of perfluoroalkoxyalkane, and therefore maintains stable strength even in high-temperature environments exceeding 200°C, so that a force pressing the outer surface of the annular spring toward the center can be stably applied to the annular spring even in high-temperature environments. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a seal load adjusting valve according to an embodiment in an open state. [Figure 2] 2 is an enlarged view of the vicinity of the seal load adjustment mechanism of the seal load adjustment valve shown in FIG. 1. [Figure 3] FIG. 2 is a perspective view of a seal load adjustment mechanism. [Figure 4] FIG. 4 is an exploded perspective view of the load adjustment mechanism shown in FIG. 3. [Figure 5]10A and 10B are diagrams for explaining the operation of the annular support member. [Figure 6] 10A and 10B are diagrams for explaining the state of the seal load adjustment mechanism in a normal temperature environment and a high temperature environment. [Figure 7] 10 is a graph for comparing the relationship between the force (reaction force) of the annular spring pushing the stem back upward and temperature under a normal temperature environment and a high temperature environment. [Figure 8] 10A and 10B are diagrams illustrating a modified example of the seal load adjustment mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of a valve according to the present invention will be described in detail with reference to FIGS. It should be noted that the present disclosure is not limited to the embodiments shown below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of elements may differ from reality. Furthermore, the drawings may include portions in which the dimensional relationships and ratios differ from one another. In addition, in this embodiment, the direction in which the stem advances and retreats is set to the up-and-down direction, and directions are shown based on this, but the direction in which the stem advances and retreats is not limited to this. For example, the stem may advance and retreat in the horizontal direction. Fig. 1 is a cross-sectional view showing a schematic configuration of a valve 1 according to an embodiment in an open state. Fig. 2 is an enlarged view of the vicinity of a sealing load adjustment mechanism 50 of the valve 1 shown in Fig. 1. Fig. 3 is a perspective view of the sealing load adjustment mechanism 50. Fig. 4 is an exploded perspective view of the sealing load adjustment mechanism 50 shown in Fig. 3. Fig. 5 is a diagram for explaining the operation of the annular support member 80. Fig. 6 is a diagram for explaining the state of the sealing load adjustment mechanism 50 in a normal temperature environment and a high temperature environment. In FIG. 6, the left side of the center line shows the vicinity of the seal load adjustment mechanism 50 in a valve-open state in a normal temperature environment, and the right side of the center line shows the vicinity of the seal load adjustment mechanism 50 in a valve-open state in a high temperature environment. The valve 1 according to the embodiment of the present invention includes an actuator 10, a valve body 30, a connecting portion 40 that connects the actuator 10 and the valve body 30, and a seal load adjustment mechanism 50. <About the actuator 10> The actuator 10 functions as a drive source for a stem 32 that drives the valve to open and close, and in this embodiment, an air actuator is used.

[0021] The actuator 10 has a case 11 in which a drive mechanism 20 is housed. The drive mechanism 20 has a piston 21 that presses the stem 32 in the valve closing direction, a spring 27 that urges the piston 21 in the valve closing direction, and an air connection part 28 that serves as a connection part to an air supply source.

[0022] <Regarding the Piston 21 of the Actuator 10> The piston 21 has a first piston 22 and a second piston 23 that divide the air chamber 25 into two with a partition wall 24 provided in the case 11 in between.

[0023] The first piston 22 has a flange portion 22a that forms a flange-shaped wall that separates the inside of the case 11 above the partition wall 24, and a protruding shaft portion 22b that protrudes from the center of the upper surface of the flange portion 22a.

[0024] The second piston 23 has a flange portion 23a that forms a flange-shaped wall that separates the inside of the case 11 below the partition wall 24, a piston-side protruding shaft portion 23b that protrudes from the central upper surface of the flange portion 23a, and a stem-side protruding shaft portion 23c that protrudes from the central lower surface of the flange portion 23a.

[0025] The piston-side protruding shaft portion 23b protrudes into the air chamber 25a on the first piston 22 side through a through hole 24a formed in the center of the partition wall 24, and is configured to abut against the flange portion 22a of the first piston 22 when the second piston 23 descends.

[0026] The stem-side protruding shaft portion 23c is in sliding contact with the inner surface of the guide hole 42 of the connecting portion 40, which has a reduced diameter compared to the inner surface of the case 11 against which the flange portion 23a of the second piston 23 is in sliding contact, and its tip surface abuts against the stem 32.

[0027] In the first piston 22 and the second piston 23, O-rings 22c and 23d are fitted onto the outer peripheral surfaces of the flange portions 22a and 23a, the protruding shaft portion 22b, the piston-side protruding shaft portion 23b, and the stem-side protruding shaft portion 23c. The first piston 22 and the second piston 23 are capable of moving in the axial direction while maintaining an airtight seal between them and the inner peripheral surface of the case 11 via the O-rings 22c and 23d.

[0028] Furthermore, the first piston 22 and the second piston 23 connect the flow paths 26 formed therein to form a continuous flow path that connects the air connection portion 28 to each of the air chambers 25a, 25b. When the supply of air to the air chambers 25a and 25b is stopped, the piston 21 is moved downward in the valve closing direction via the flange portion 22a of the first piston 22, which is pressed by the elastic force of the spring 27.

[0029] On the other hand, when air is supplied from an air supply source via air connection 28, air fills each of air chambers 25a, 25b through flow passages 26 formed in pistons 22, 23. As a result, pistons 22, 23 are moved upward in the valve opening direction against the elastic force of spring 27 by the pressure of the air filling each of air chambers 25a, 25b.

[0030] <About the valve body 30> The valve body 30 includes a body 31, a stem 32, a diaphragm 34, a diaphragm piece 35, and a retaining member 36.

[0031] <About Body 31> The body 31 is made of, for example, stainless steel and has a generally rectangular parallelepiped appearance. As shown in FIG. 2, a stem 32, a diaphragm 34, a diaphragm piece 35, and a retaining member 36 are provided inside the body 31, with the central axis A being concentric therewith. The body 31 is formed with a primary flow path 31a on the upstream side into which the control fluid flows and a secondary flow path 31b on the downstream side through which the control fluid flows out, and a ring-shaped valve seat 33 is provided on the opening edge surface that penetrates the primary flow path 31a upward and opens toward the valve chamber 31d. The valve seat 33 is made of, for example, perfluoroalkoxyalkane (PFA).

[0032] <About Stem 32> The stem 32 has a generally cylindrical appearance, one end of which abuts against the stem-side protruding shaft portion 23c of the second piston 23, and the other end of which abuts against the diaphragm piece 35. The outer peripheral surface of the stem 32 is in sliding contact with the inner peripheral surface of the guide hole 42 of the connecting portion 40, so that the stem 32 is guided in the up and down direction, which is the forward and backward direction. This stem 32 has a small diameter shaft portion 32a formed at the lower end thereof that abuts against the diaphragm piece 35 via a stepped surface 32b, and this stepped surface 32b is a surface that is approximately perpendicular to the central axis of the stem 32 that abuts against the bulging surface 61 of the annular spring 60 described later. The small diameter shaft portion 32 a is a portion that abuts against the upper surface of the diaphragm piece 35 and presses the diaphragm 34 toward the valve seat 33 via the diaphragm piece 35 .

[0033] <About Diaphragm 34> The diaphragm 34 is provided so as to be able to move toward and away from the valve seat 33 inside the body 31, and functions as a valve element that abuts against the valve seat 33 to seal the opening that connects the primary flow path 31a and the secondary flow path 31b. The diaphragm 34 is made of a metal such as a nickel-cobalt alloy and has an approximately disk-like shape, and its outer peripheral edge 34a is clamped and fixed between a step 31c formed on the inner surface of the body 31 and the lower outer peripheral edge 36d of the retaining member 36. In this embodiment, when assembling the diaphragm 34 inside the body 31, the outer peripheral edge 34a of the diaphragm 34 is placed on the step 31c of the body 31, and then the lower end outer peripheral edge 36d of the retaining member 36 is placed on top of the diaphragm 34 so that it overlaps the outer peripheral edge 34a of the diaphragm 34. Then, with the outer peripheral edge 34a of the diaphragm 34 sandwiched between the step 31c and the retaining member 36, the connecting portion 40 and the body 31 are screwed together, whereby the diaphragm 34 is sandwiched and fixed inside the body 31. The diaphragm 34 with its outer peripheral edge 34 a fixed in this manner is capable of elastically deforming such that the region inside the outer peripheral edge 34 a can freely move toward and away from the valve seat 33 .

[0034] <Regarding the holding member 36> The holding member 36 holds the diaphragm piece 35 so that it can move freely along the central axis A. As described above, the holding member 36 also clamps and fixes the outer peripheral edge portion 34a of the diaphragm 34 from above the step portion 31c of the body 31. This retaining member 36 has a cross section perpendicular to the central axis A that is approximately annular, and in the center is formed a stem insertion hole 36a through which the small diameter shaft portion 32a of the stem 32 is inserted and which protrudes toward the diaphragm piece 35. A guide recess 36b is formed in the center of the lower end surface of the holding member 36 to hold the diaphragm piece 35, which has a substantially circular cross section perpendicular to the central axis A, so that the diaphragm piece 35 can move freely along the central axis A.

[0035] An annular member-mounting groove 37 is formed in the upper end surface 36c of the holding member 36, and is disposed opposite the annular groove 41 formed in the lower end surface 40a of the connecting portion 40. An annular support member 80 and an annular thermal expansion member 70 of the seal load adjustment mechanism 50, which will be described later, are arranged between the member mounting annular groove 37 of the holding member 36 and the annular groove 41 of the connecting portion 40.

[0036] <Regarding the connecting portion 40> The connecting portion 40 connects the actuator 10 and the valve body 30. The upper end of the connecting portion 40 is screwed into the lower end of the case 11 of the actuator 10 and connected to the case 11. The lower end of the connecting portion 40 is screwed into the upper end of the body 31 of the valve main body 30 and connected to the valve main body 30 . The lower end of this connecting portion 40 has a cross section perpendicular to the central axis A that is approximately annular, and its lower end surface 40a is adapted to abut against the upper end surface 36c of the holding member 36, which also has an approximately annular cross section, so that the lower end of the connecting portion 40 and the upper end of the holding member 36 are connected by abutting each other's upper and lower end surfaces 40a, 36c. Furthermore, as the fastening operation by screwing the connecting portion 40 and the body 31 proceeds, the connecting portion 40 pushes the retaining member 36 downward, thereby clamping and fixing the outer peripheral edge portion 34a of the diaphragm 34 between the step portion 31c of the body 31 and the lower end outer peripheral edge portion 36d of the retaining member 36, and connecting the lower end portion of the connecting portion 40 and the upper end portion of the retaining member 36.

[0037] <Regarding the seal load adjustment mechanism 50> The seal load adjustment mechanism 50 includes an annular spring 60, an annular thermal expansion member 70, and an annular support member 80.

[0038] <About Annular Spring 60> The annular spring 60 has a bulging surface 61 that is bulged at least in the central portion symmetrically with the central axis A and is positioned so as to be able to abut against the stem 32 so as to apply an upward elastic force to the stem 32 when the stem 32 is lowered to the valve closed position. In this embodiment, the annular spring 60 is made of so-called spring steel, and is a circular plate-shaped member with an upper surface that bulges out in a dome shape, for example. In addition, as long as the annular spring 60 has a shape in which at least the central portion bulges symmetrically with respect to the central axis A, it may have, for example, a dome-shaped bulge in the central portion and a flange-like protrusion in the radially outward direction.

[0039] The annular spring 60 is disposed inside the body 31 with the small diameter shaft portion 32 a of the stem 32 passing through an insertion hole 60 a formed in the center thereof, and the bulging surface 61 can freely abut against the stepped surface 32 b of the stem 32 . More specifically, the annular spring 60 is arranged in a position concentric with the stem 32 inside the body 31, with the small diameter shaft portion 32a of the stem 32 passing through the insertion hole 60a and with the outer peripheral end portion 62 supported by the annular support member 80. In a room temperature environment, when the valve is closed, this annular spring 60 is set so that the bulged surface 61, which is the upper surface, is just in contact with the stepped surface 32b of the stem 32 or is lightly pressing against the stepped surface 32b. The annular spring 60 is elastically deformed so as to increase the resilient force that pushes the stem 32 in the direction away from the diaphragm 34 in accordance with the amount of expansion of the annular thermal expansion member 70 toward the center that increases with increasing temperature.

[0040] <Regarding the annular thermal expansion member 70> The annular thermal expansion member 70 is positioned with its inner surface 70b facing outward from the outer surface 60b of the annular spring 60, and applies a force to the annular spring 60 that presses the outer surface 60b of the annular spring 60 toward the center due to thermal expansion. In this embodiment, the annular thermal expansion member 70 is made of a material with high heat resistance and a high linear expansion coefficient, such as perfluoroalkoxyalkane (PFA), and has an inner diameter set larger than the outer diameter of the annular support member 80. The annular thermal expansion member 70 can be made of various highly heat-resistant materials as long as they have a linear expansion coefficient greater than that of the members arranged around the annular thermal expansion member 70, such as the annular support member 80.

[0041] As described above, annular groove 41 (first annular groove) and member-mounting annular groove 37 (second annular groove) are formed on the upper and lower end faces 40a, 36c of connecting portion 40 and holding member 36, which are connected by abutting their end faces in the central axis direction. The annular thermal expansion member 70 is disposed between the annular groove 41 and the member-mounting annular groove 37 . Furthermore, the annular thermal expansion member 70 is disposed so as to be in contact with the groove outer peripheral surfaces 37b, 41b which are connected flush with each other and the opposing groove bottom surfaces 37a, 41a. As a result, the annular thermal expansion member 70 is positioned so as to block the connection portion between the lower end of the connecting portion 40 and the upper end of the holding member 36, which are connected by abutting their end faces, from the inside of the annular groove 41 and the member-mounting annular groove 37. Therefore, the annular thermal expansion member 70 expands thermally as the temperature rises, thereby improving the sealing performance of the connecting portion between the connecting portion 40 and the holding member 36.

[0042] The annular thermal expansion member 70 is arranged between the annular groove 41 and the component-mounting annular groove 37 in a press-fit state, with its outer circumferential surface 70a flush with the connecting groove outer circumferential surfaces 37b, 41b. This allows the annular thermal expansion member 70 to redirect radially outward expansion toward the radially inward direction, thereby efficiently expanding radially inward. In this embodiment, the annular thermal expansion member 70 is illustrated as being arranged so as to be in contact with the flush-connected groove outer peripheral surfaces 37b, 41b and the opposing groove bottom surfaces 37a, 41a, but this is not limited to this. As long as the annular thermal expansion member 70 can be thermally expanded radially inward, it may be arranged with a gap between it and the flush-connected groove outer peripheral surfaces 37b, 41b and the opposing groove bottom surfaces 37a, 41a.

[0043] <Regarding the annular support member 80> The annular support member 80 supports the outer peripheral surface 60b of the annular spring 60 so as to be able to press the outer peripheral surface 60b toward the center. In this embodiment, the annular support member 80 is made of, for example, stainless steel (SUS) or brass, and as shown in FIG. 5, is configured by four divided arc portions 81, 82, 83, and 84 that are divided equally into four in the circumferential direction. The annular support member 80 is not limited to being divided into four parts, and may be divided into other numbers, for example, three parts or six parts.

[0044] This annular support member 80 is arranged such that the end faces 81a, 82a, 83a, 84a of the respective divided arc portions 81, 82, 83, 84 face each other, and the inner and outer diameters can be adjusted so as to be expandable and contractible by changing the interval S3 between the end faces 81a, 82a, 83a, 84a facing each other. As shown in FIGS. 4 and 5, each of the divided arc portions 81, 82, 83, 84 has a cross-sectional L-shaped configuration having a flange portion 80a protruding inwardly in a flange shape and a standing wall portion 80b provided standing with respect to the flange portion 80a. In a state where the four divided arc portions 81, 82, 83, 84 are arranged circularly with their end faces 81a, 82a, 83a, 84a facing each other, the outer peripheral end portion 62 of the annular spring 60 is placed on the upper surface of the flange portion 80a.

[0045] Such an annular support member 80 is arranged to be movable in the radial direction on the inner peripheral surface 70b side of the annular thermal expansion member 70. More specifically, the annular support member 80 is arranged between the member mounting annular groove 37 of the holding member 36 and the annular groove 41 of the connecting portion 40 so as to be movable in the radial direction according to the amount of expansion when the annular thermal expansion member 70 thermally expands. For example, as shown in FIG. 6, let the radial width of the annular thermal expansion member 70 in a normal temperature environment be w1, the radial width of the flange portion 80a of the annular support member 80 be w2, the radial width of the standing wall portion 80b of the annular support member 80 be w3, the width of the gap of the annular groove 41 be S1, the radial width of the groove bottom surface 41a of the annular groove 41 be A1, the width of the gap of the member mounting annular groove 37 be S2, and the radial width of the groove bottom surface 37a of the member mounting annular groove 37 be A2. Then, the relational expression A1 = w1 + w2 + S1 holds. Also, the relational expression A2 = w1 + w3 + S2 holds. And the relation S1 < S2 is satisfied. For this reason, the width of the gap in which the annular support member 80 can move in the radial direction is determined by the width S1 of the gap of the annular groove 41. The gap S1 through which the annular support member 80 can move radially is adjusted to a width that allows the annular spring 60 to be elastically deformed by utilizing the amount of radial expansion of the annular thermal expansion member 70 so that the annular spring 60 applies an upward elastic force to the stem 32 according to the temperature.

[0046] The gap S1 varies depending on the amount of expansion of the annular thermal expansion member 70, which increases with increasing temperature. In other words, in a room temperature environment, the amount of expansion of the annular thermal expansion member 70 is minimized, and the gap S1 is at its maximum value. In this room temperature environment, as described above, when the valve is closed, the bulged surface 61, which is the upper surface, is in contact with the stepped surface 32b of the stem 32 or lightly presses against the stepped surface 32b. Furthermore, even if the bulging surface 61 of the annular spring 60 is pressed down by the stem 32, the outer peripheral end 62 of the annular spring 60 shifts radially outward by utilizing the gap S1, so that the spring force pushing back in the opposite direction to the diaphragm 34 is less likely to act on the stem 32.

[0047] On the other hand, as the temperature rises from room temperature, the amount of expansion of the annular thermal expansion member 70 increases, and the expanded annular thermal expansion member 70 presses the annular support member 80, moving it toward the center C, so that the gap S1 becomes smaller in accordance with the amount of expansion, and eventually, as shown to the right of the center line in Figure 6, the upright wall portion 80b of the annular support member 80 abuts against the inner groove surface 41c of the annular groove 41. In this way, as the annular thermal expansion member 70 expands, the annular support member 80 moves toward the center C, reducing its diameter, and when it moves toward the center C by the gap S1, it abuts against the inner groove surface 41c of the annular groove 41. In other words, the gap S1 on the annular groove 41 side determines the maximum expansion amount of the annular thermal expansion member 70. Therefore, by adjusting the size of the gap S1 on the annular groove 41 side, the amount of thermal expansion of the annular thermal expansion member 70 can be set in advance, thereby making it possible to determine the upper limit of the force that presses the outer end portion 62 of the annular spring 60 toward the center C due to the expansion of the annular thermal expansion member 70. Thus, by setting the upper limit value of the force pressing the annular spring 60 toward the center C, it is possible to adjust the resilient force applied to the stem 32 by the annular spring 60, and it is possible to prevent the annular spring 60 from being damaged by applying an excessive pressing force to the annular spring 60. In this embodiment, although an example is given in which S1 < S2 and the gap S1 on the annular groove 41 side determines the maximum expansion amount of the annular thermal expansion member 70, it may be configured such that S2 < S1 and the gap S2 on the annular groove 37 side for member placement determines the maximum expansion amount of the annular thermal expansion member 70. Furthermore, it may be configured such that S1 = S2 and the maximum expansion amount of the annular thermal expansion member 70 is determined by both the gap S1 on the annular groove 41 side and the gap S2 on the annular groove 37 side for member placement.

[0048] Also, the interval S3 between the end faces 81a, 82a, 83a, 84a of the respective divided arc portions 81, 82, 83, 84 of the annular support member 80 facing each other is set so as to satisfy the relationship of S3 > 0 when the above-described gap S1 becomes S1 = 0, that is, when the annular support member 80 abuts against the inner peripheral surface 41c of the groove of the annular groove 41 and the thermal expansion amount of the annular thermal expansion member 70 reaches the predetermined maximum expansion amount. However, if the interval S3 of the respective divided arc portions 81, 82, 83, 84 when the gap S1 becomes S1 = 0 is too large, it becomes difficult to stably support the outer peripheral end portion 62 of the annular spring 60 by the annular support member 80. Therefore, the interval S3 is preferably set to the smallest possible value within the range that satisfies the above-described dimensional conditions while considering component interference. <​​​​​​First, as shown on the left side of the center line in Figure 6, for example, in a room temperature environment of 25°C, the annular thermal expansion member 70 does not thermally expand, so its radial width is the width w1 before thermal expansion, and it is positioned between the member mounting annular groove 37 and the annular groove 41 with a gap S1 that allows it to move radially. In this state, the annular spring 60 is in a neutral elastic state, and is disposed with a gap H1 between the stepped surface 32b of the stem 32 and the bulging surface 61 when the valve is open.

[0051] On the other hand, as shown to the right of the center line, in a high temperature environment of, for example, 200° C. or higher, the radial width of the annular thermal expansion member 70 becomes a width w4 that is larger than the width w1 before thermal expansion due to thermal expansion. As a result, the outer peripheral surface 80c of the annular support member 80, which is arranged on the inner peripheral surface 70b side of the annular thermal expansion member 70, is pressed toward the center C by the inner peripheral surface 70b of the expanded annular thermal expansion member 70. When the annular support member 80 is pressed toward the center C by the annular thermal expansion member 70, as shown in Figure 5, each divided arc portion 81, 82, 83, 84 moves toward the center C so as to reduce the distance S3 between the opposing end faces 81a, 82a, 83a, 84a. As a result, the inner diameter of the annular support member 80, which is composed of four divided arc portions 81, 82, 83, and 84 arranged in a circle, becomes smaller, and the upright wall portion 80b forming the inner surface 80d of the annular support member 80 pushes the outer peripheral end portion 62 of the annular spring 60 toward the center C.

[0052] In this way, as the temperature rises, the annular support member 80 moves toward the center C using the gap S1, and the annular spring 60 is pressed toward the center C by the four divided arc portions 81, 82, 83, and 84 arranged in a circle.

[0053] 6, the annular spring 60 is elastically deformed and curved symmetrically about the central axis A so that the bulging surface 61 is lifted upward in the drawing. In this way, when the annular spring 60 is elastically deformed so as to lift the bulging surface 61 upward in a high temperature environment, when the valve is opened, the gap H2 between the stepped surface 32b of the stem 32 becomes smaller than the gap H1 in a normal temperature environment. The bulging surface 61 of the annular spring 60 is positioned higher in a high temperature environment than in a normal temperature environment, so that the annular spring 60 stores a larger resilience force that pushes back the stem 32 in the opposite direction to the diaphragm 34 than in a normal temperature environment. Therefore, when the valve is closed, the step surface 32b of the stem 32 abuts against the bulging surface 61 of the annular spring 60 and pushes the bulging surface 61 down to the valve closed position, and the annular spring 60, which has stored a larger resilience than under normal temperature conditions, applies a larger force to the stem 32, pushing it back in the opposite direction from the diaphragm 34. In addition, in a high temperature environment, the bulging surface 61 of the annular spring 60 is positioned higher, and the gap S1 through which the outer peripheral end 62 of the annular spring 60 can move radially outward becomes smaller or is eliminated, so the annular spring 60 does not move radially outward and a greater elastic force is stably applied to the stem 32.

[0054] <Assembly procedure for the seal load adjustment mechanism 50> When assembling the seal load adjustment mechanism 50 to the valve 1, the worker places the annular support member 80, the annular spring 60, and the annular thermal expansion member 70 on the groove bottom surface 37a of the member mounting annular groove 37 in this order, for example. Since this assembly work is performed at room temperature, the above-mentioned gap S1 is set to its maximum design size, so that no pressing force is applied from the annular support member 80 to the annular spring 60 toward the center C. Therefore, when setting the annular support member 80 in the member-mounting annular groove 37, the worker does not need to set it so that the intervals S3 between the end faces 81a, 82a, 83a, 84a of the divided arcuate portions 81, 82, 83, 84 are equal. That is, the worker can set the annular support member 80 in the member-mounting annular groove 37 without worrying about variations in the interval S3. Furthermore, as described above, when the amount of thermal expansion of the annular thermal expansion member 70 reaches a predetermined maximum amount of expansion, the spacing S3 is set to be as small as possible while satisfying the relationship S3 > 0. Therefore, even if there is variation in the spacing S3 at the time of initial assembly, by repeatedly operating the valve 1, the divided arc portions 81, 82, 83, and 84 will move so as to reduce the variation in the spacing S3.

[0055] <Relationship between the temperature and the force (reaction force) that the seal load adjustment mechanism 50 exerts on the stem 32 in the direction opposite to the diaphragm 34> Here, the results of an analysis conducted by the present inventors regarding the relationship between the temperature and the force (reaction force) that the seal load adjustment mechanism 50 applies to push the stem 32 in the direction opposite to the diaphragm 34 will be described with reference to FIG. FIG. 7 is a graph showing the relationship between the force (reaction force) that the seal load adjustment mechanism 50 applies to push the stem 32 in the direction away from the diaphragm 34 and the stroke amount of the stem 32 under normal temperature and high temperature environments. 7, the horizontal axis indicates the stroke amount (mm) of the stem 32, and the vertical axis indicates the force (reaction force) that the seal load adjustment mechanism 50 pushes back in the direction opposite to the diaphragm . The solid line indicates the graph under high temperature (200°C) conditions, and the dashed line indicates the graph under room temperature (25°C) conditions. In the graph, the position where the bulging surface 61 of the annular spring 60 contacts the step surface 32b of the stem 32 under room temperature conditions is taken as the stroke amount of 0.0 mm. In addition, in the graph for high temperature conditions, the stroke amount starts from -0.34 mm, which indicates that thermal expansion of the annular thermal expansion member 70 and the annular spring 60 caused the annular spring 60 to become 0.34 mm higher in the opposite direction to the diaphragm 34.

[0056] As is clear from comparing the two graphs for the room temperature condition and the high temperature condition, when comparing the reaction forces at the same stroke amount, all reaction forces are larger under the high temperature condition than under the room temperature condition. Therefore, in the stroke amount of the stem 32 when the valve is closed, a larger reaction force can be applied to the stem 32 by the annular spring 60 in a high temperature environment than in a normal temperature environment. From the results of this analysis, the inventors discovered that by using an annular thermal expansion member 70 and an annular spring 60 that is elastically deformed so as to increase the reaction force applied to the stem 32 in accordance with the increase in the amount of expansion of the annular thermal expansion member 70, a reaction force corresponding to the temperature increase can be applied to the stem 32, and an appropriate load corresponding to the strength of the valve seat 33 can be applied to the valve seat 33 that has been softened by high temperatures.

[0057] <Valve 1 opening and closing operation> Next, the opening and closing operation of the valve 1 will be described. When the valve 1 changes from a closed state to an open state (see FIG. 1), the drive mechanism 20 moves the stem 32 to the upper end of its stroke, and the diaphragm 34 to the open position. More specifically, air is introduced into the flow path 26 from an air supply source (not shown) through the air connection part 28, and the air is supplied through the flow path 26 to the two air chambers 25a and 25b.

[0058] When air is supplied to the two air chambers 25a, 25b, the first piston 22 is moved upward against the biasing force of the spring 27 by the pressure of the air filled in the upper air chamber 25a, and the second piston 23 is also moved upward to follow the upward movement of the first piston 22 by the pressure of the air filled in the lower air chamber 25b. Then, the stem 32, which had been pushed downward by the pistons 22, 23, is released from the load of the pistons 22, 23 and moves upward together with the diaphragm piece 35, and the elastic restoring force of the diaphragm 34 separates the diaphragm 34 from the valve seat 33, entering the valve open state.

[0059] As the stem 32 moves upward, the annular spring 60 that has been pressed downward by the stem 32 elastically returns to its original position. Here, in a high temperature environment, the annular spring 60 is elastically deformed by being curved symmetrically about the central axis A so as to lift the bulging surface 61 upward, as described above.

[0060] On the other hand, when the valve 1 changes from an open state to a closed state, as air is discharged from the two air chambers 25a, 25b, the air pressure that was moving the two pistons 22, 23 upward decreases, and the first piston 22 on the upper side is pushed downward by the force of the spring 27, which in turn pushes the second piston 23 on the lower side downward. Then, the stem 32 is pushed downward by the second piston 23, and the diaphragm 34 is pushed downward via the diaphragm piece 35, so that the diaphragm 34 comes into contact with the valve seat 33, resulting in a valve-closed state.

[0061] In this way, when the stem 32 is moved downward to the valve closed state, the stepped surface 32b of the stem 32 abuts against the bulging surface 61 of the annular spring 60, and the stem 32 presses the annular spring 60 downward. Here, in a high temperature environment, as shown in Figure 6, the annular thermal expansion member 70 thermally expands and elastically deforms via the annular support member 80 so as to increase the resilient force that pushes the annular spring 60 in the opposite direction to the diaphragm 34. As a result, the annular spring 60 is elastically deformed by bending symmetrically about the central axis A so as to further lift the bulging surface 61 upward, so that the gap H2 between the step surface 32b of the stem 32 when the valve is open becomes smaller than the gap H1 under normal temperature conditions, and when the valve is closed, a greater elastic force is applied to the step surface 32b of the stem 32 than under normal temperature conditions.

[0062] In this state, when the stem 32 pushes the annular spring 60 downward, the elastic repulsive force of the annular spring 60 acts on the stem 32 with a greater reaction force than in a room temperature environment. More specifically, when the annular spring 60 is pushed downward by the stem 32, the bulging surface 61, which is positioned higher than in a room temperature environment as described above, is elastically deformed so that it is pushed down along the central axis A, and the elastically restoring spring force is applied to the stem 32 as a force pushing the stem 32 back upward. Furthermore, when the annular spring 60 elastically deforms to cause the bulging surface 61 to become concave, the gap S1 is smaller than in a room temperature environment, or there is no gap S1, so the spring does not reduce its elastic force by elastically deforming to expand in a direction perpendicular to the central axis A of the stem 32, but rather the position of the bulging surface 61 is raised and the bulging surface 61 is pushed down while its elastic force is increased.

[0063] Furthermore, the seal load adjustment mechanism 50 is configured so that the annular thermal expansion member 70 increases its expansion amount as the temperature rises, and the annular spring 60 applies to the stem 32 a reaction force that increases as the temperature rises. In other words, a substantially constant load is applied to the stem 32 in the valve closing direction by the drive mechanism 20, but as the temperature rises, the force pushing back in the opposite direction to the diaphragm 34 increases due to the amount of expansion of the annular thermal expansion member 70 that corresponds to the temperature, and the load applied through the stem 32 to the valve seat 33, which has softened as the temperature rises, is reduced, and an appropriate load is applied to the valve seat 33 according to the strength of the valve seat 33 in a high-temperature environment.

[0064] <Effects of the First Embodiment> As described above, in the valve 1 according to the embodiment, the seal load adjustment mechanism 50 comprises: an annular spring 60 having a bulging surface 61, at least the central portion of which bulges symmetrically with respect to the central axis A, arranged so as to be able to freely abut against the stem 32, so as to apply a resilient force to the stem 32 in the opposite direction to the diaphragm 34 when the stem 32 is moved to the valve closed position; and an annular thermal expansion member 70, arranged with its inner circumferential surface 70b facing outward from the outer circumferential surface 60b of the annular spring 60, which applies a force to the annular spring 60 that presses the outer circumferential surface 60b of the annular spring 60 toward the center C due to thermal expansion. As a result, the annular spring 60 is elastically deformed symmetrically about the central axis A so as to increase the elastic force pushing the stem 32 in the opposite direction to the diaphragm 34 as the annular thermal expansion member 70 increases in expansion toward the center C as the temperature rises. Therefore, by using the annular thermal expansion member 70 and the annular spring 60, the reaction force pushing the stem 32 in the opposite direction to the diaphragm 34 can be increased as the temperature rises, and as a result, deformation of the valve seat 33 can be suppressed and a decrease in sealing performance can be prevented even in high-temperature environments, despite the simple configuration.

[0065] Furthermore, according to the valve 1 of the embodiment, the seal load adjustment mechanism 50 further has an annular support member 80 that supports the outer peripheral surface 60b of the annular spring 60 so as to be able to press the outer peripheral surface 60b of the annular spring 60 toward the center C, and when the amount of expansion of the annular thermal expansion member 70 increases, the annular support member 80 presses the annular spring 60 toward the center C. This allows the annular support member 80 to more reliably apply the pressing force applied to the annular spring 60 when the annular thermal expansion member 70 expands to the annular spring 60 as a force pressing toward the center C. Therefore, the annular spring 60 can be elastically deformed more stably so that the elastic force that pushes back the stem 32 in the opposite direction to the diaphragm 34 increases in accordance with the amount of expansion of the annular thermal expansion member 70.

[0066] Furthermore, in the valve 1 according to this embodiment, the connecting portion 40 and the holding member 36 are connected by abutting their end faces 40a, 36c in the direction of the central axis A. The first annular groove 41 and the second annular groove 37 are formed on the outer peripheral edges of the abutting lower end face 40a of the connecting portion 40 and the upper end face 36c of the holding member 36, respectively, so that the groove bottom faces 41a, 37a face each other and the groove outer peripheral faces 37b, 41b are connected flush. The annular thermal expansion member 70 is disposed between the annular groove 41 and the member-mounting annular groove 37, and is disposed so as to contact the flush-connected groove outer peripheral faces 37b, 41b and the opposing groove bottom faces 37a, 41a. As a result, the annular thermal expansion member 70 is positioned so as to block the connecting portion between the connecting portion 40 and the holding member 36, where the upper and lower end faces 40a, 36c are abutted, from the inside of the annular groove 41 and the member-mounting annular groove 37. Therefore, the annular thermal expansion member 70 seals the connected parts in the direction of the central axis A, and furthermore, the annular thermal expansion member 70 expands thermally as the temperature rises, thereby further improving the sealing properties of the connected parts.

[0067] Furthermore, in the valve 1 according to the embodiment, the annular support member 80 is made of metal, so that the pressing force acting on the annular spring 60 when the annular thermal expansion member 70 expands can be more stably applied toward the center C by the strong annular support member 80.

[0068] Furthermore, according to the valve 1 of the embodiment, the annular thermal expansion member 70 is made of perfluoroalkoxyalkane, and therefore maintains stable strength even in high-temperature environments exceeding 200°C, so that a force pressing the outer surface 60b of the annular spring 60 toward the center C can be stably applied to the annular spring 60 even in high-temperature environments.

[0069] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0070] For example, in the above embodiment, a pressing force toward the center C obtained by thermal expansion of the annular thermal expansion member 70 is applied to the annular spring 60 via the annular support member 80, but the pressing force toward the center C obtained by thermal expansion of the annular thermal expansion member 70 may be applied directly to the annular spring 60 without going through the annular support member 80. For example, as shown in Fig. 8, the shape of the annular support member 80 may be given to the annular thermal expansion member 70, or the annular support member 80 may be embedded in the annular thermal expansion member 70 to form an integrated unit.

[0071] Furthermore, for example, in the above embodiment, the stem 32 is moved up and down using the actuator 10 as a drive source, but the stem 32 may be moved up and down using a manual handle as a drive source.

[0072] Furthermore, for example, in the above embodiment, a diaphragm valve was used as an example of the valve 1, but the present invention is not limited to this, and other valves may be used as long as they control the flow of high-temperature fluid by opening and closing the valve body by moving the stem to approach and separate it from the valve seat. For example, a bellows valve or a hanging-type diaphragm valve may be used.

[0073] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0074] 1 valve 32 Stem 33 Valve seat 34 Diaphragm (valve body) 36 Retaining member (connected part) 36c Top surface 37 Component placement annular groove 37a Groove bottom surface 37b Groove outer surface 40 Connection part (connected part) 40a Lower end surface 41 Annular groove 41a Groove bottom surface 41b Groove outer surface 50 Seal load adjustment mechanism 60 Annular spring 60b Outer surface 61 Bulging surface 70 Annular thermal expansion member 70b Inner surface 80 Annular support member

Claims

1. a stem that is arranged to be freely movable back and forth along the central axis and that, when the valve is closed, moves toward the valve element to apply a sealing load that brings the valve element into contact with the valve seat, thereby sealing; and a sealing load adjustment mechanism that adjusts the sealing load applied to the valve seat by the stem. The seal load adjustment mechanism includes an annular spring having a bulging surface, at least a central portion of which is bulged symmetrically with respect to the central axis, arranged so as to be able to abut against the stem so as to apply a resilient force to the stem in the opposite direction to the valve body when the stem is moved to a valve closed position; and an annular thermal expansion member, arranged with its inner peripheral surface facing outward from the outer peripheral surface of the annular spring, which applies a force to the annular spring by thermal expansion that presses the outer peripheral surface of the annular spring toward the center, The valve is characterized in that the annular spring elastically deforms to increase the resilient force pushing the stem in the opposite direction to the valve body in response to an increase in the amount of expansion toward the center of the annular thermal expansion member as the temperature rises.

2. the seal load adjustment mechanism further includes an annular support member that supports the outer circumferential surface of the annular spring so as to be able to press the outer circumferential surface of the annular spring toward the center, The valve according to claim 1 , wherein the annular thermal expansion member presses the annular spring toward the center via the annular support member when the amount of expansion of the annular thermal expansion member increases.

3. a first annular groove and a second annular groove are formed at the portion where the end faces are connected by abutting against each other in the central axis direction, so that the groove bottom surfaces face each other at the edges of the abutting end faces and that the groove outer circumferential surfaces are connected flush with each other; 3. The valve according to claim 1, wherein the annular thermal expansion member is disposed between the first annular groove and the second annular groove and is disposed so as to contact the flush-connected groove outer peripheral surface and the opposing groove bottom surface.

4. 3. The valve of claim 2, wherein the annular support member is made of metal.

5. 2. The valve of claim 1, wherein the annular thermal expansion member is made of a perfluoroalkoxyalkane.

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