Steam valve

Abstract

A steam valve according to at least one embodiment includes a valve seat and a valve core. The valve core and the valve seat each have: a first layer formed on a base material and made of a material different from the base material; and a second layer formed on the first layer at least at a contact position of the valve core and the valve seat and made of a material different from the base material and the first layer. At least one of one side and the other side of a steam flow path separated by the contact position of the valve core and the valve seat, with respect to at least either of the valve core and the valve seat, a minimum radius of curvature of the first layer in a cross section along a relative movement direction of the valve core and the valve seat is a radius of curvature of the smaller one of a minimum radius of curvature of a surface of the base material and a minimum radius of curvature of a surface of the second layer.

Description

TECHNICAL FIELD

[0001] The present application relates to a steam valve.

[0002] This application claims priority from Japanese Patent Application No. 2021-077778 filed on April 30, 2021, and the contents thereof are incorporated herein by reference. BACKGROUND

[0003] For example, in a steam valve used in an application of controlling a flow rate of steam supplied to a steam turbine or the like, in order to suppress abrasion caused by high-temperature and high-pressure steam flowing at high speed, a cobalt-based alloy or the like is used for build-up welding (see Patent Literature 1).

[0004] PRIOR ART DOCUMENTS

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2012-61514 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] For example, in the technology described in Patent Literature 1, in order to suppress cracking of the build-up layer of the cobalt-based alloy, a build-up layer of a nickel-based alloy is formed between the base material made of an iron-based alloy and the build-up layer, to prevent melting of iron from the base material into the build-up layer.

[0008] However, the build-up layer of the nickel-based alloy is soft compared to the build-up layer of the cobalt-based alloy. Therefore, it is required to suppress abrasion that occurs in a portion of the build-up layer that is present on the surface of a member of the steam valve.

[0009] In view of the above, an object of at least one embodiment of the present application is to suppress abrasion of a member in a steam valve.

[0010] TECHNICAL SOLUTION FOR SOLVING THE PROBLEMS

[0011] (1) A steam valve according to at least one embodiment of the present application includes:

[0012] a valve seat; and

[0013] a valve core;

[0014] the valve core and the valve seat each have:

[0015] a first layer formed on a base material and made of a material different from that of the base material; and

[0016] a second layer formed on the first layer at least at a position where the valve core and the valve seat are in contact with each other, and made of a material different from that of the base material and the first layer,

[0017] At least one of the side and the other side of the steam flow path, which are separated by the contact position of the valve element and the valve seat, with respect to at least either of the valve element and the valve seat, the minimum radius of curvature of the first layer in the cross section along the direction of relative movement of the valve element and the valve seat is the smaller one of the minimum radius of curvature of the surface of the base material and the minimum radius of curvature of the surface of the second layer.

[0018] Inventive Effects

[0019] According to at least one embodiment of the present application, it is possible to suppress the wear of components in a steam valve. BRIEF DESCRIPTION OF DRAWINGS

[0020] FIG. 1A is a schematic cross-sectional view of a valve seat and a valve element of a steam valve according to one embodiment.

[0021] FIG. 1B is a schematic cross-sectional view showing a state of valve closing in the steam valve shown in FIG. 1A

[0022] FIG. 2 is a schematic cross-sectional view of a valve seat and a valve element of a steam valve according to another embodiment.

[0023] FIG. 3 is a schematic cross-sectional view of a valve seat and a valve element of a steam valve according to still another embodiment.

[0024] FIG. 4 is a schematic cross-sectional view of a valve seat and a valve element of a steam valve according to still another embodiment.

[0025] FIG. 5 is a schematic cross-sectional view of a valve seat of a steam valve according to still another embodiment.

[0026] FIG. 6 is a graph for explaining the stress at the interface of the base material and the first layer and the stress at the interface of the first layer and the second layer when the thickness of the first layer is changed. DETAILED DESCRIPTION

[0027] Hereinafter, several embodiments of the present application will be described with reference to the accompanying drawings. However, the size, material, shape, and relative arrangement of the constituent components described as embodiments or shown in the drawings are not intended to limit the scope of the present application thereto, and are merely illustrative.

[0028] ​For example, expressions indicating a relative or absolute arrangement such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" indicate not only such an arrangement but also a state of relative displacement with an angle or distance having a tolerance or to an extent that the same function can be obtained.

[0029] For example, expressions indicating a state where things are the same such as "same", "equal", and "uniform" indicate not only a state where things are strictly the same but also a state where there is a difference having a tolerance or to an extent that the same function can be obtained.

[0030] For example, expressions indicating a shape such as a quadrangular shape or a cylindrical shape indicate not only a shape in a strict geometrical sense such as a quadrangular shape or a cylindrical shape but also a shape including a concave-convex portion or a chamfered portion and the like within a range where the same effect can be obtained.

[0031] On the other hand, expressions such as "provided with", "equipped with", "furnished with", "including", and "having" one component are not exclusive expressions that exclude the presence of other components.

[0032] Hereinafter, a steam valve according to several embodiments will be described.

[0033] FIG. 1A is a schematic cross-sectional view of a valve seat and a valve core of a steam valve according to one embodiment.

[0034] FIG. 1B is a schematic cross-sectional view indicating a state where the steam valve shown in FIG. 1A is closed.

[0035] FIG. 2 is a schematic cross-sectional view of a valve seat and a valve core of a steam valve according to another embodiment.

[0036] FIG. 3 is a schematic cross-sectional view of a valve seat and a valve core of a steam valve according to still another embodiment.

[0037] FIG. 4 is a schematic cross-sectional view of a valve seat and a valve core of a steam valve according to still another embodiment.

[0038] FIG. 5 is a schematic cross-sectional view of a valve seat of a steam valve according to still another embodiment.

[0039] A steam valve 100 according to several embodiments is provided with a valve seat 110 having a valve seat surface 110a facing a steam flow path 101 inside the valve, and a valve core 160 having a valve core surface 160a facing the steam flow path 101.

[0040] In the steam valve 100 according to the embodiments, the flow rate of steam flowing in the steam flow path 101 is controlled by relatively moving the valve seat 110 and the valve core 160, more specifically, by moving the valve core 160 with respect to the valve seat 110 fixed to the valve case (not shown) along the central axis AXb of the valve core 160. That is, the extending direction of the central axis AXb of the valve core 160 is also the relative moving direction of the valve seat 110 and the valve core 160.

[0041] In the steam valve 100 according to the embodiments, the valve seat 110 has a first layer 113 formed on the base material 111 and made of a material different from that of the base material 111, and a second layer 115 formed on the first layer 113 at least at the contact position 103 of the valve core 160 and the valve seat 110 and made of a material different from those of the base material 111 and the first layer 113.

[0042] Specifically, the base material 111 of the valve seat 110 according to the embodiments is formed of an iron-based alloy. In the valve seat 110 according to the embodiments, the first layer 113 is formed of, for example, a nickel-based alloy. In the valve seat 110 according to the embodiments, the second layer 115 is formed of, for example, a cobalt-based alloy.

[0043] In the valve seat 110 according to the embodiments, the second layer 115 is a build-up layer formed from one side to the other side of the steam flow path 101 across the contact position 103 of the valve core 160. In the valve seat 110 according to the embodiments, the first layer 113 is a build-up barrier layer provided between the base material 111 and the second layer 115 in order to suppress cracking of the second layer 115 of the cobalt-based alloy.

[0044] In the steam valve 100 according to the embodiments, the valve core 160 has a first layer 163 formed on the base material 161 and made of a material different from that of the base material 161, and a second layer 165 formed on the first layer 163 at least at the contact position 103 of the valve core 160 and the valve seat 110 and made of a material different from those of the base material 161 and the first layer 163.

[0045] Specifically, the base material 161 of the valve core 160 according to the embodiments is formed of an iron-based alloy. In the valve core 160 according to the embodiments, the first layer 163 is formed of, for example, a nickel-based alloy. In the valve core 160 according to the embodiments, the second layer 165 is formed of, for example, a cobalt-based alloy.

[0046] In the valve element 160 according to the embodiments, the second layer 165 is a cladding layer formed from one side to the other side of the steam flow path 101 across the contact position 103 with the valve seat 110. In the valve element 160 according to the embodiments, the first layer 163 is a cladding layer provided between the base material 161 and the second layer 165 in order to suppress cracking of the second layer 165 of the cobalt-based alloy.

[0047] In the steam valve 100 according to the embodiments, as described above, in order to suppress wear of the valve seat 110 and the valve element 160 due to the flow of steam at a relatively high temperature and high pressure at a high speed in the steam flow path 101, cladding of the second layer 115, 165 based on a cobalt-based alloy is performed.

[0048] In addition, if a cladding layer of a cobalt-based alloy is directly formed on a base material 111, 161 made of an iron-based alloy, the cladding layer can be peeled off from the base material 111, 161 during use. Therefore, in the steam valve 100 according to the embodiments, as described above, the first layer 113, 163 is arranged between the base material 111, 161 and the second layer 115, 165.

[0049] In the steam valve 100 according to the embodiments, in the steam valve 100 according to the embodiments, in a case where the valve seat 110 and the valve element 160 are in abutment, for example, as shown in FIG. 1, the second layers 115, 165 are arranged so that the second layer 115 of the valve seat 110 and the second layer 165 of the valve element 160 are in abutment. FIG. 1B

[0050] (Material of the base material 111, 161)

[0051] In the steam valve 100 according to the embodiments, the alloy of the iron-based that is the material of the base material 111, 161 is preferably a heat-resistant material of the Fe-based that has been used in the valve element or the valve seat of the steam valve in the past, that is, a material called heat-resistant steel, and is not substantially limited, but for example, a heat-resistant steel containing 75% by mass or more of Fe, containing one or more alloying elements of Cr, Mo, V, W, Nb, or the like for improving heat resistance is preferred. The steel grade and the steel composition of the heat-resistant steel are not particularly limited, and for example, Cr steels such as 9Cr steel, 12Cr steel, Cr-Mo steels, Cr-Mo-V steels, and the like are representative. Specifically, for example, SUH1, SUH3, SUH4, SUH11, SUH600, SUH616, or the like specified by JIS G 4311, or a heat-resistant steel similar thereto can be mentioned.

[0052] (Material of the first layer 113, 163)

[0053] ​In the steam valve 100 according to the embodiments, the nickel-based alloy as the material of the first layer 113, 163 can be, for example, INCONEL 625, INCONEL 82, or the like. Note that INCONEL is a registered trademark.

[0054] (Material of the second layer 115, 165)

[0055] In the steam valve 100 according to the embodiments, the cobalt-based alloy as the material of the second layer 115, 165 can be, for example, a Co-Cr-based heat-resistant alloy known as a trade name "Stellite" or a Co-Cr-based heat-resistant alloy similar to Stellite. The composition of the Co-Cr-based heat-resistant alloy is, for example, preferably Cr: 24 to 32%, W: 0 to 20%, C: 0.2 to 3.5%, Mo: 0 to 6%, Ni: 0 to 25%, Fe: 3% or less, and the balance of Co and impurities, in terms of mass%.

[0056] (Abrasion suppression with respect to the first layer 113, 163)

[0057] As described above, the first layer 113, 163 according to the embodiments is formed of a nickel-based alloy. Therefore, the first layer 113, 163 is soft as compared with the second layer 115, 165 formed of a cobalt-based alloy. Therefore, it is required to suppress abrasion in the first layer 113, 163 that occurs in a portion of the surface of the valve seat 110 or the valve core 160 (valve seat surface 110a and valve core surface 160a).

[0058] In the following description, with respect to the valve seat 110 and the valve core 160, when referred to as a "surface", it is the surface facing the steam flow passage 101 in the valve unless otherwise specified. That is, in the following description, with respect to the valve seat 110 and the valve core 160, when referred to as a "surface", it means at least a portion of the valve seat surface 110a and the valve core surface 160a unless otherwise specified.

[0059] For example, when the surface 113a, 163a of the first layer 113, 163 protrudes from the surface 111a, 161a of the base material 111, 161, the surface 115a, 165a of the second layer 115, 165, or the like, the flow of steam is disturbed at the surface 113a, 163a of the first layer 113, 163, or the like, and thus the surface 113a, 163a of the first layer 113, 163 is easily abraded.

[0060] Therefore, the surface 113a, 163a of the first layer 113, 163 is preferably formed as a smooth curved surface together with the surface 111a, 161a of the base material 111, 161 and the surface 115a, 165a of the second layer 115, 165 adjacent to the surface 113a, 163a. That is, in the steam valve 100 according to the embodiments,FIG. 1A through FIG. 5 In the cross section shown in the plane including the central axis AXb of the spool 160, the surface 113a, 163a of the first layer 113, 163 is preferably formed so as to exhibit a smooth curve or straight line together with the surface 111a, 161a of the base material 111, 161 adjacent to the surface 113a, 163a and the surface 115a, 165a of the second layer 115, 165.

[0061] In addition, in the valve seat surface 110a of the valve seat 110 shown in FIG. 1A , FIG. 1B and FIG. 2 through FIG. 4 , the valve seat surface 110a is a plane including the central axis AXb of the spool 160, i.e., the upper surface 110u and the inner peripheral surface 110i corresponding to the inner peripheral surface of a cylinder centered on the central axis AXb of the spool 160. In addition, in the valve seat 110 shown in FIG. 1A , FIG. 1B and FIG. 2 through FIG. 4 , the upper surface 110u and the inner peripheral surface 110i can be conical surfaces.

[0062] In the valve seat 110 shown in FIG. 1A , FIG. 1B and FIG. 2 , the upper surface 110u and the inner peripheral surface 110i are represented by straight lines.

[0063] In the valve seat 110 shown in FIG. 3 , FIG. 1A , FIG. 1B and FIG. 1A , the upper surface 110u and the inner peripheral surface 110i are smoothly connected by a curved surface, i.e., a connecting surface 110j, which exhibits a curve in the cross section shown in each figure.

[0064] In the valve seat 110 shown in FIG. 1B and FIG. 1A , the interface 117 between the base material 111 and the first layer 113 appears on the upper surface 110u and the inner peripheral surface 110i.

[0065] In addition, in the valve seat 110 shown in FIG. 1B and FIG. 2 , in the cross section shown in FIG. 3 and FIG. 2 , the radius of curvature of the connecting surface 110j can be constant regardless of the position thereof, or can be different depending on the position.

[0066] In the valve seat 110 shown in FIG. 3 and FIG. 2 , the interface 117 between the base material 111 and the first layer 113 appears on the connecting surface 110j.

[0067] In addition, in the valve seat 110 shown in FIG. 3 andFIG. 4 In the valve seat 110 shown, in FIG. 4 and FIG. 5 In the cross-section shown, the radius of curvature of the connecting surface 110j can be constant regardless of its position, or it can vary depending on its position.

[0068] However, when the radius of curvature of the connecting surface 110j varies depending on the position, the minimum radius of curvature of the surface 113a of the first layer 113 can be greater than the smaller of the minimum radius of curvature of the surface 111a of the parent material 111 and the minimum radius of curvature of the surface 115a of the second layer 115.

[0069] exist FIG. 5 In the valve seat 110 shown, the inner circumferential surface 110i is smoothly connected to the connecting surface 110j.

[0070] exist FIG. 5 In the valve seat 110 shown, the upper surface 110u and the connecting surface 110j are connected at an intersection at the corner 111b, which will be described later.

[0071] exist FIG. 5 The valve seat surface 110a of the valve seat 110 shown includes an upper surface 110u, a plane orthogonal to the central axis AXb of the valve core 160, and an inner circumferential surface 110k, which will be described below. Additionally, in FIG. 5 In the valve seat 110 shown, the upper surface 110u can also be a conical surface.

[0072] FIG. 1A The inner circumferential surface 110k shown is in FIG. 1B In the cross-section shown, the minimum radius of curvature r is located at a position along the central axis AXb of the valve core 160, relatively close to the upper surface 110u. min At a position along the central axis AXb of valve core 160 that is farther from the upper surface 110u than the aforementioned radius of curvature r min A large radius of curvature r. Furthermore, this radius of curvature r can be constant regardless of its position, or it can vary depending on the position.

[0073] exist FIG. 2 In the valve seat 110 shown, the interface 117 between the base material 111 and the first layer 113 appears in the region of the inner circumferential surface 110k with the radius of curvature r.

[0074] exist FIG. 3 , FIG. 1A , FIG. 1B and FIG. 2In the spool surface 160a of the spool 160 shown, an outer peripheral surface 160o corresponding to the outer peripheral surface of a cylinder or a circular column centered on the center axis AXb of the spool 160 and a conical surface 160c corresponding to a conical surface centered on the center axis AXb of the spool 160 are included. In addition, in the spool 160 shown in FIG. 3 , FIG. 1A , FIG. 1B and FIG. 2 the outer peripheral surface 160o can also be a conical surface.

[0075] In FIG. 3 , FIG. 1A , FIG. 1B and FIG. 2 , the outer peripheral surface 160o and the conical surface 160c are represented by straight lines.

[0076] In FIG. 3 , FIG. 1A , FIG. 1B and FIG. 1A , the outer peripheral surface 160o and the conical surface 160c are smoothly connected by a curved surface, i.e., a connecting surface 160j, which is represented by a curve in the cross section shown in each figure.

[0077] In FIG. 1B and FIG. 1A , the interface 167 between the base material 161 and the first layer 163 appears on the outer peripheral surface 160o and the conical surface 160c.

[0078] In addition, in the spool 160 shown in FIG. 1B and FIG. 2 , in the cross sections shown in FIG. 3 and FIG. 2 , the radius of curvature of the connecting surface 160j can be constant regardless of its position, or can be different depending on the position.

[0079] In FIG. 3 and FIG. 2 , the interface 167 between the base material 161 and the first layer 163 appears on the conical surface 160c in the region approaching the valve seat 110 across the contact position 103, and appears on the connecting surface 110j in the region away from the valve seat 110 across the contact position 103.

[0080] In addition, in the spool 160 shown in FIG. 3 and FIG. 4 , in the cross sections shown in FIG. 4 and FIG. 4 , the radius of curvature of the connecting surface 110j can be constant regardless of its position, or can be different depending on the position.

[0081] However, in a case where the radius of curvature of the connection surface 110j differs depending on the position, the minimum radius of curvature of the surface 163a of the first layer 163 can be equal to or greater than the smaller one of the minimum radius of curvature of the surface 161a of the base material 161 and the minimum radius of curvature of the surface 165a of the second layer 165.

[0082] In FIG. 4 the spool surface 160a of the spool 160 illustrated, an outer peripheral surface 160o that corresponds to the outer peripheral surface of a cylinder or a circular column centered on the central axis AXb of the spool 160 and an outer peripheral surface 160m described below are included. In addition, in FIG. 4 the spool 160 illustrated, the outer peripheral surface 160o can also be a conical surface.

[0083] FIG. 1A through FIG. 5 The outer peripheral surface 160m illustrated is in FIG. 1A through FIG. 5 the cross section illustrated, has a minimum radius of curvature r min at a position farther from the valve seat 110 along the central axis AXb of the spool 160. In addition, the radius of curvature r min may be constant regardless of the position, or can differ depending on the position.

[0084] In FIG. 1A through FIG. 5 the spool 160 illustrated, the interface 167 between the base material 161 and the first layer 163 is present in the region of the outer peripheral surface 160m having the radius of curvature r.

[0085] Therefore, in the steam valve 100 related to several embodiments, as FIG. 1A through FIG. 5 illustrated, in FIG. 1A the cross section illustrated, the surfaces 113a, 163a of the first layers 113, 163 are formed in such a manner that the surfaces 113a, 163a and the surfaces 111a, 161a of the base materials 111, 161 adjacent to the surfaces 113a, 163a, the surfaces 115a, 165a of the second layers 115, 165 are expressed as a smooth curve or a straight line.

[0086] Thus, the wear of the surfaces 113a, 163a of the first layers 113, 163 can be suppressed.

[0087] In addition, in order to suppress the wear of the surfaces 113a, 163a of the first layers 113, 163, in FIG. 1B the cross section illustrated, the radius of curvature r1 of the surfaces 113a, 163a of the first layers 113, 163 is preferably large.

[0088] Therefore, in the steam valve 100 according to the embodiments, at least one of the one side and the other side of the steam flow path 101 separated by the contact position 103 of the spool 160 and the valve seat 110, the minimum radius of curvature of the first layer 113, 163 in the cross section along the direction of relative movement of the spool 160 and the valve seat 110 with respect to at least one of the spool 160 or the valve seat 110 is equal to or greater than the smaller one of the minimum radius of curvature of the surface of the base material 111, 161 or the minimum radius of curvature of the surface of the second layer 115, 165.

[0089] That is, in the steam valve 100 according to the embodiments, at least one of the spool surface 160a or the valve seat surface 110a on at least one of the one side and the other side of the steam flow path 101 separated by the contact position 103, the minimum radius of curvature of the first layer 113, 163 in the cross section along the direction of relative movement of the spool 160 and the valve seat 110 is equal to or greater than the smaller one of the minimum radius of curvature of the surface of the base material 111, 161 or the minimum radius of curvature of the surface of the second layer 115, 165. FIG. 1A In the above cross section, the surface 115a, 165a of the second layer 115, 165 or the surface 111a, 161a of the base material 111, 161 has the smallest radius of curvature r. In other words, the minimum radius of curvature of the first layer 113, 163 is not smaller than the minimum radius of curvature of the surface of the base material 111, 161 or the minimum radius of curvature of the surface of the second layer 115, 165.

[0090] For example, in the embodiments of FIG. 2 and FIG. 3 , as shown in FIG. 4 , the minimum radius of curvature r min of the surface of the valve seat 110 is the radius of curvature r2 of the surface 115a of the second layer 115, and the minimum radius of curvature r min of the surface of the spool 160 is the radius of curvature r2 of the surface 165a of the second layer 165.

[0091] For example, in the embodiments of FIG. 4 and FIG. 5 , the minimum radius of curvature r min of the surface of the valve seat 110 is the radius of curvature r2 of the surface 115a of the second layer 115, and the minimum radius of curvature r min of the surface of the spool 160 is the radius of curvature r2 of the surface 165a of the second layer 165.

[0092] For example, in the embodiment of FIG. 1A through FIG. 5 , the minimum radius of curvature r min of the surface of the valve seat 110 is the radius of curvature r0 of the surface 111a of the base material 111, and the minimum radius of curvature r min of the surface of the spool 160 is the radius of curvature r0 of the surface 161a of the base material 161.

[0093] Further, in the embodiments of FIG. 1A through FIG. 5In the valve seat 110, the base material 111 has a corner 111b that convexes toward the steam flow path 101. Since the corner 111b is exposed in the steam flow path 101, the radius of curvature of the surface of the corner 111b is the smallest in the valve seat 110.

[0094] For example, in FIG. 1A through FIG. 5 In the embodiment, the minimum radius of curvature r of the surface of valve seat 110 min It is the radius of curvature r0 of the surface 111a of the parent material 111.

[0095] Therefore, in FIG. 1A through FIG. 2 In the cross-section shown above, the radius of curvature r1 of surfaces 113a and 163a of the first layer 113 and 163 is the minimum radius of curvature r of the surface of valve core 160 or valve seat 110. min Therefore, the radius of curvature r1 of the surfaces of the first layers 113 and 163 is smaller than the minimum radius of curvature r of the surfaces 111a and 161a of the parent materials 111 and 161. min and the minimum radius of curvature r of surfaces 115a and 165a of the second layer 115 and 165 min The smaller of the two radii of curvature r min Compared to the previous situation, it can suppress the wear of the surfaces 113a and 163a of the first layer 113 and 163 caused by the high-temperature and high-pressure steam flowing at high speed in the steam flow path 101 inside the valve.

[0096] (Regarding the intersection angle θ at intersection point P)

[0097] like FIG. 1A through FIG. 2 As shown, in several embodiments, in FIG. 1A through FIG. 2 In the cross-section shown above, the intersection angle θ between the interfaces 117 and 167 of the parent materials 111 and 161 and the first layers 113 and 163 and the surfaces 111a and 161a of the parent materials 111 and 161 can be greater than 90 degrees at the intersection position P of the interfaces 117 and 167 and the surfaces 111a and 161a of the parent materials 111 and 161.

[0098] Therefore, compared with the case where the intersection angle θ is less than 90 degrees at the intersection position P, when the first layer 113 and 163 are welded onto the base materials 111 and 161, the shape of the corner of the base materials 111 and 161 corresponding to the intersection position P is not easily deformed.

[0099] (Regarding the extension direction of interfaces 117 and 167 at the intersection point P)

[0100] exist FIG. 4In the illustrated embodiment, in the cross-sections of the valve core 160 shown in the figures, the aforementioned intersection P occurs at two locations, one radially inner and one radially outer, centered on the central axis AXb of the valve core 160. The extension direction of the interface 167 at the radially inner intersection P can be inclined relative to the central axis AXb such that it approaches the central axis AXb as the valve core 160 moves towards the valve seat 110 in the direction of movement of the valve core 160.

[0101] That is, in FIG. 1A through FIG. 2 In the embodiment shown, the tangent L6 of the interface 167 at the aforementioned intersection position P on the radially inner side can be inclined relative to the central axis AXb in such a way that it approaches the central axis AXb in the direction of movement toward the valve core 160 as the valve core 160 approaches the valve seat 110.

[0102] Near the aforementioned radially inner intersection P, the interface 171 approaches the radially inner side as the valve core 160 moves towards the valve seat 110 in the direction of movement towards the valve core 160. Therefore, when viewing the valve core 160 before the formation of the first layer 163 along the central axis AXb from the valve seat 110 side, the surface of the bevel of the valve core 160, i.e., the surface of the base material 161 to which the first layer 163 is to be formed, is not hidden in the portion corresponding to the aforementioned radially inner intersection P. Therefore, when the valve core 160 before the formation of the first layer 163 is welded along the central axis AXb from the valve seat 110 side to form the first layer 163, the portion corresponding to the aforementioned radially inner intersection P will not be an obstacle when forming the first layer 163. Thus, the first layer 163 can be easily formed on the valve core 160.

[0103] In addition, FIG. 4 and FIG. 3 In the illustrated embodiment, in the cross-sections of the valve seat 110 shown in the figures above, the aforementioned intersection P appears at two locations, one radially inner and one radially outer, centered on the central axis AXb of the valve core 160. The extension direction of the interface 117 at the radially outer intersection P can be inclined relative to the central axis AXb in such a way that it approaches the central axis AXb as the valve core 160 moves toward the valve seat 110 in the direction of movement of the valve core 160.

[0104] That is, in FIG. 4 and FIG. 3 In the embodiment shown, the tangent L1 of the interface 117 at the aforementioned cross position P on the radially outer side can be inclined relative to the central axis AXb in such a way that it approaches the central axis AXb as the valve core 160 approaches the valve seat 110 in the direction of movement toward the valve core 160.

[0105] In the vicinity of the above-described intersection position P on the radially outer side, the interface 117 approaches the radially outer side as the valve core 160 approaches the valve seat 110 in the direction of movement toward the valve core 160. Therefore, when the valve seat 110 before the first layer 113 is formed is viewed from the valve core 160 side along the central axis AXb, the surface of the bevel of the valve seat 110, that is, the surface of the base material 111 where the first layer 113 is to be formed is not hidden in the portion corresponding to the above-described intersection position P on the radially outer side. Therefore, in the case where the valve seat 110 before the first layer 113 is formed is welded from the valve core 160 side along the central axis AXb to form the first layer 113, the portion corresponding to the above-described intersection position P on the radially outer side does not become an obstacle when the first layer 113 is formed. Thus, the first layer 113 is easily formed on the valve seat 110.

[0106] In FIG. 4 and FIG. 3 the embodiments shown, the intersection position P on the radially outer side of the valve core 160 is present at two positions, one on the radially inner side and the other on the radially outer side, with the central axis AXb of the valve core 160 as the center. The extension direction of the interface 167 at the intersection position P on the radially inner side of the two intersection positions P can be inclined with respect to the central axis AXb in such a manner as to move away from the central axis AXb as the valve core 160 approaches the valve seat 110 in the direction of movement toward the valve core 160. FIG. 4 and FIG. 3 In the above-described cross-sectional view, the intersection position P is present at two positions, one on the radially inner side and the other on the radially outer side, with the central axis AXb of the valve core 160 as the center. The extension direction of the interface 167 at the intersection position P on the radially inner side of the two intersection positions P can be inclined with respect to the central axis AXb in such a manner as to move away from the central axis AXb as the valve core 160 approaches the valve seat 110 in the direction of movement toward the valve core 160.

[0107] That is, in the embodiments shown in FIG. 5 and FIG. 3 , the tangent line L6 of the interface 167 at the intersection position P on the radially inner side can be inclined with respect to the central axis AXb in such a manner as to move away from the central axis AXb as the valve core 160 approaches the valve seat 110 in the direction of movement toward the valve core 160.

[0108] In the vicinity of the above-described intersection position P on the radially inner side, the interface 167 approaches the radially outer side as the valve core 160 approaches the valve seat 110 in the direction of movement toward the valve core 160. Therefore, even if the first layer 163 is peeled off from the base material 161 at the interface 167, the first layer 163 is not easily detached from the base material 161 toward the direction in which the valve core 160 approaches the valve seat 110 because the first layer 163 interferes with the above-described intersection position P on the radially inner side.

[0109] Further, in the embodiments shown in FIG. 5 and FIG. 3 , the intersection position P on the radially inner side of the valve core 160 is present at two positions, one on the radially inner side and the other on the radially outer side, with the central axis AXb of the valve core 160 as the center. The extension direction of the interface 167 at the intersection position P on the radially inner side of the two intersection positions P can be inclined with respect to the central axis AXb in such a manner as to move away from the central axis AXb as the valve core 160 approaches the valve seat 110 in the direction of movement toward the valve core 160. FIG. 5 FIG. 6 ​In the cross-sectional view shown, the intersection position P occurs at two positions on the radially inner side and the radially outer side of the center axis AXb of the valve element 160. The extension direction of the interface 117 at the radially outer intersection position P of the two intersection positions P can be inclined with respect to the center axis AXb in such a manner as to move away from the center axis AXb as the valve element 160 approaches the valve seat 110 in the direction of movement toward the valve element 160.

[0110] That is, in the embodiment shown, the tangent line L1 of the interface 117 at the radially outer intersection position P can be inclined with respect to the center axis AXb in such a manner as to move away from the center axis AXb as the valve element 160 approaches the valve seat 110 in the direction of movement toward the valve element 160. FIG. 6 and FIG. 6 That is, in the embodiment shown, the tangent line L1 of the interface 117 at the radially outer intersection position P can be inclined with respect to the center axis AXb in such a manner as to move away from the center axis AXb as the valve element 160 approaches the valve seat 110 in the direction of movement toward the valve element 160.

[0111] In the vicinity of the radially outer intersection position P, the interface 117 approaches the radially inner side as the valve element 160 moves away from the valve seat 110 in the direction of movement toward the valve element 160. Therefore, even if the first layer 113 peels off from the base material 111 at the interface 117, the first layer 113 is not easily detached from the base material 111 toward the direction in which the valve element 160 moves away from the valve seat 110, because the first layer 113 interferes with the radially outer intersection position P.

[0112] (Thickness of the first layer 113, 163)

[0113] ​ A graph for explaining the stress at the interface 117, 167 between the base material 111, 161 and the first layer 113, 163 and the stress at the interface 118, 168 between the first layer 113, 163 and the second layer 115, 165 when the thickness of the first layer 113, 163 is changed. In addition, in the graph of ​ , the thickness of the first layer 113, 163 is taken on the horizontal axis, and the stress when the thickness of the first layer 113, 163 is 0, that is, when the stress on the interface between the base material 111, 161 and the second layer 115, 165 is taken as 1, is taken on the vertical axis. In addition, the thickness of the base material 111, 161 and the second layer 115, 165 is constant. In addition, the stress referred to here is a thermal stress caused by the difference in the linear expansion coefficient of the base material 111, 161, the first layer 113, 163, and the second layer 115, 165.

[0114] As is clear from the graph of ​ , as the thickness of the first layer 113, 163 increases, the stress at the interface 117, 167 between the base material 111, 161 and the first layer 113, 163 and the stress at the interface 118, 168 between the first layer 113, 163 and the second layer 115, 165 decrease.

[0115] This is because the magnitude of the linear expansion coefficient of the nickel-based alloy constituting the first layer 113, 163 is between the magnitude of the linear expansion coefficient of the iron-based alloy constituting the base material 111, 161 and the magnitude of the linear expansion coefficient of the cobalt-based alloy constituting the second layer 115, 165.

[0116] However, as the thickness of the first layer 113, 163 increases, the cost required to form the first layer 113, 163 also increases.

[0117] In addition, since the cobalt-based alloy constituting the second layer 115, 165 is also a relatively expensive alloy, it is desirable to use as little of it as possible.

[0118] In view of these circumstances, the ratio of the thickness of the second layer 115, 165 to the thickness of the first layer 113, 163 can be in the range of 1:2 to 2:1.

[0119] The present application is not limited to the above-described embodiments, and also includes embodiments obtained by modifying the above-described embodiments and embodiments obtained by appropriately combining these embodiments.

[0120] The content described in each of the above-described embodiments can be grasped, for example, as follows.

[0121] (1) The steam valve 100 according to at least one embodiment of the present application includes a valve seat 110 and a valve core 160. The valve core 160 and the valve seat 110 each include a first layer 113, 163 formed on a base material 111, 161 and having a different material from the base material 111, 161, and a second layer 115, 165 formed on the first layer 113, 163 at least at a contact position 103 of the valve core 160 and the valve seat 110 and having a different material from the base material 111, 161 and the first layer 113, 163. In at least one of one side and the other side of a steam flow path 101 separated by the contact position 103 of the valve core 160 and the valve seat 110, the minimum radius of curvature of the first layer 113, 163 in a cross section along a relative movement direction of the valve core 160 and the valve seat 110 with respect to at least either of the valve core 160 and the valve seat 110 is equal to or greater than the smaller one of the minimum radius of curvature of a surface of the base material 111, 161 and the minimum radius of curvature of a surface of the second layer 115, 165.

[0122] According to the structure of the above (1), in a cross section along a relative movement direction of the valve core 160 and the valve seat 110, the radius of curvature of a surface of the first layer 113, 163 is equal to or greater than the minimum radius of curvature r minTherefore, the radius of curvature r1 of the surfaces of the first layers 113 and 163 is smaller than the minimum radius of curvature r of the surfaces 111a and 161a of the parent materials 111 and 161. min and the minimum radius of curvature r of surfaces 115a and 165a of the second layer 115 and 165 min The smaller of the two radii of curvature r min Compared to the previous situation, it can suppress the wear of the surfaces 113a and 163a of the first layer 113 and 163 caused by the high-temperature and high-pressure steam flowing at high speed in the steam flow path 101 inside the valve.

[0123] (2) In several embodiments, in the structure described in (1) above, the intersection angle θ between the interfaces 117 and 167 between the parent materials 111 and 161 and the first layers 113 and 163 and the surfaces 111a and 161a of the parent materials 111 and 161 is 90 degrees or more at the intersection position P of the interfaces 117 and 167 and the surfaces 111a and 161a of the parent materials 111 and 161.

[0124] According to the structure described in (2), compared to the case where the cross angle θ is less than 90 degrees at the cross position P, when the first layer 113 and 163 are welded onto the base materials 111 and 161, the shape of the corner of the base materials 111 and 161 corresponding to the cross position P is not easily deformed.

[0125] (3) In several embodiments, in the structure described in (2) above, the aforementioned intersection P may appear at two locations radially inner and outer, centered on the central axis AXb of the valve core 160, in the aforementioned cross section of the valve core 160. The extension direction of the interface 167 at the radially inner intersection P at these two locations is inclined relative to the central axis AXb such that it approaches the central axis AXb as the valve core 160 moves toward the valve seat 110 in the aforementioned direction of movement.

[0126] According to the structure described in (3) above, near the aforementioned intersection P on the radially inner side, the interface 171 approaches the radially inner side as the valve core 160 approaches the valve seat 110 in the direction of movement described above. Therefore, when the valve core 160 before the formation of the first layer 163 is viewed from the valve seat 110 side along the central axis AXb, the surface of the bevel of the valve core 160, i.e., the surface of the base material 161 to which the first layer 163 is to be formed, is not hidden in the portion corresponding to the aforementioned intersection P on the radially inner side. Therefore, when the valve core 160 before the formation of the first layer 163 is welded from the valve seat 110 side along the central axis AXb to form the first layer 163, the portion corresponding to the aforementioned intersection P on the radially inner side will not become an obstacle when forming the first layer 163. As a result, the first layer 163 can be easily formed on the valve core 160.

[0127] (4) In several embodiments, in the structure of (2) or (3) above, it can also be that, in the cross section of the valve seat 110, the intersection position P occurs at two places on the radially inner side and outer side of the center axis AXb of the valve core 160. The extension direction of the interface 117 at the intersection position P on the radially outer side of the two places is inclined with respect to the center axis AXb in such a manner that it approaches the center axis AXb as the valve core 160 in the movement direction approaches the valve seat 110.

[0128] According to the structure of (4) above, in the vicinity of the intersection position P on the radially outer side above, the interface 117 approaches the radially outer side as the valve core 160 in the movement direction moves away from the valve seat 110. Therefore, when the valve seat 110 before the formation of the first layer 113 is viewed from the valve core 160 side along the center axis AXb, the surface of the bevel of the valve seat 110, that is, the surface of the base material 111 where the first layer 113 is to be formed, does not hide in the portion corresponding to the intersection position P on the radially outer side above. Therefore, in the case where the first layer 113 is formed by welding the valve seat 110 before the formation of the first layer 113 from the valve core 160 side along the center axis AXb, the portion corresponding to the intersection position P on the radially outer side above does not become an obstacle in the formation of the first layer 113. Thus, the first layer 113 is easily formed on the valve seat 110.

[0129] (5) In several embodiments, in the structure of (2) above, it can also be that, in the cross section of the valve core 160, the intersection position P occurs at two places on the radially inner side and outer side of the center axis AXb of the valve core 160. The extension direction of the interface 167 at the intersection position P on the radially inner side of the two places is inclined with respect to the center axis AXb in such a manner that it moves away from the center axis AXb as the valve core 160 in the movement direction approaches the valve seat 110.

[0130] According to the structure of (5) above, in the vicinity of the intersection position P on the radially inner side above, the interface 167 approaches the radially outer side as the valve core 160 in the movement direction approaches the valve seat. Therefore, assuming that even if the first layer 163 peels off from the base material 161 at the interface 167, the first layer 163 does not easily fall off from the base material 161 toward the direction in which the valve core 160 approaches the valve seat 110 due to the interference of the first layer 163 with the intersection position P on the radially inner side above.

[0131] (6) In several embodiments, in the structure of (2) or (5) above, it can also be that, in the cross section of the valve seat 110 above, the intersection position P above occurs at 2 places on the radially inner side and outer side of the center axis AX of the valve core 160. The extension direction of the interface 117 at the radially outer intersection position P of the 2 places of the intersection position P above is inclined with respect to the center axis AXb in such a way that it moves away from the center axis AXb as the valve core 160 in the movement direction approaches the valve seat 110.

[0132] According to the structure of (6) above, in the vicinity of the radially outer intersection position P above, the interface 117 approaches the radially inner side as the valve core 160 in the movement direction moves away from the valve seat 110. Therefore, assuming that even if the first layer 113 peels off from the base material 111 at the interface 117, since the first layer 113 interferes with the radially outer intersection position P above, the first layer 113 is not easily detached from the base material 111 toward the direction in which the valve core 160 moves away from the valve seat 110.

[0133] Reference Signs List

[0134] 100 Steam valve

[0135] 101 Steam flow path

[0136] 103 Contact position

[0137] 110 Valve seat

[0138] 111 Base material

[0139] 113 First layer

[0140] 115 Second layer

[0141] 117 Interface

[0142] 160 Valve core

[0143] 161 Base material

[0144] 163 First layer

[0145] 165 Second layer

[0146] 167 Interface

Claims

1. A steam valve, comprising: Valve seat; and Valve core; The valve core and the valve seat respectively have: The first layer is formed on the base material, and its material is different from that of the base material; and The second layer is formed on the first layer, at least at the contact position between the valve core and the valve seat, and is made of a different material than the base material and the first layer. The first layer is designed to prevent the second layer from cracking. On at least one side of the steam flow path separated by the contact position between the valve core and the valve seat, the radius of curvature of the surface facing the steam flow path of at least either the valve core or the valve seat, is greater than or equal to the smaller of the radius of curvature of the surface of the base material and the radius of curvature of the surface of the second layer in a cross-section along the relative movement direction of the valve core and the valve seat.

2. The steam valve according to claim 1, wherein, In the cross section, the angle between the interface between the base material and the first layer and the surface of the base material is greater than 90 degrees at the intersection of the interface and the surface of the base material.

3. The steam valve according to claim 2, wherein, In the cross-section of the valve core, the intersection points appear at two locations, one radially inner and one radially outer, centered on the central axis of the valve core. The extension direction of the interface at the radially inner intersection of the two locations is inclined relative to the central axis in such a way that it approaches the central axis as the valve core moves toward the valve seat in the direction of movement.

4. The steam valve according to claim 2 or 3, wherein, In the cross-section of the valve seat, the intersection points appear at two locations, one radially inner and one radially outer, centered on the central axis of the valve core. The extension direction of the interface at the radially outer intersection of the two locations is inclined relative to the central axis in such a way that it approaches the central axis as the valve core moves toward the valve seat in the direction of movement.

5. The steam valve according to claim 2, wherein, In the cross-section of the valve core, the intersection points appear at two locations, one radially inner and one radially outer, centered on the central axis of the valve core. The extension direction of the interface at the radially inner intersection of the two locations is inclined relative to the central axis in such a way that it moves away from the central axis as the valve core approaches the valve seat in the direction of movement.

6. The steam valve according to claim 2 or 5, wherein, In the cross-section of the valve seat, the intersection points appear at two locations, one radially inner and one radially outer, centered on the central axis of the valve core. The extension direction of the interface at the radially outer intersection of the two locations is inclined relative to the central axis in such a way that it moves away from the central axis as the valve core approaches the valve seat in the direction of movement.

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