Diaphragm

Abstract

To provide a diaphragm which enables easy design which satisfies requirements of member strength, such as corrosion resistance, pressure resistance, and durability, while maintaining deformation performance.SOLUTION: A diaphragm 47 partitions an operation chamber 48e in which a fluid flows from a storage space 10a different from the operation chamber 48e. The diaphragm 47 includes: a first member 47a provided at the operation chamber 48e side; and a second member 47b provided at the storage space 10a side. The first member 47a has a predetermined level of corrosion resistance to at least the fluid. The second member 47b is formed by a material different from that of the first member 47a. The first member 47a and the second member 47b are stacked as separated parts.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, diaphragms have been used as partitions that separate a predetermined space (see, for example, Patent Document 1). The diaphragm described in Patent Document 1 separates a space (operating chamber) into which a fluid is introduced and a space that houses a pair of metal terminals that switch between a conductive state and a non-conductive state in response to movement of an operating shaft. The diaphragm deforms or displaces to displace the operating shaft in the axial direction and switch between a conductive state and a non-conductive state of the pair of metal terminals, so it is required to have a certain degree of deformability (ease of bending). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility Model Registration No. 3226571 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described diaphragm, increasing the thickness of the diaphragm to a certain extent is one way to improve its durability (the period during which the diaphragm can maintain its function after repeated use; hereinafter, simply referred to as durability). However, this increases the rigidity of the diaphragm, making it difficult to increase the amount of diaphragm displacement (decreasing deformability), and thus making it difficult to ensure a sufficient stroke of the operating shaft, which moves in response to the diaphragm's displacement. While it is possible to improve the diaphragm's deformability by reducing the diaphragm's thickness or changing the material, this tends to reduce its pressure resistance. Furthermore, if the fluid that the diaphragm comes into contact with is corrosive, restrictions also apply to the materials that can be used. Therefore, there is limited freedom in selecting materials and setting the thickness to meet the required deformability, making it difficult to design a diaphragm that maintains deformability while also meeting the required component strengths, such as corrosion resistance, pressure resistance, and durability.

[0005] An object of the present invention is to provide a diaphragm that can be easily designed and that satisfies the required member strength such as corrosion resistance, pressure resistance, and durability while maintaining deformability. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, the diaphragm of the present invention is a diaphragm that separates a fluid space through which a fluid flows and another space separate from the fluid space, and is characterized in that it comprises a first member provided on the fluid space side and a second member provided on the other space side, the first member having a predetermined corrosion resistance at least to the fluid, the second member being made of a material different from the first member, and the first member and the second member being stacked as separate bodies.

[0007] According to the present invention, by laminating the first and second members separately, stresses generated when the diaphragm deforms can be generated separately in the first and second members. Therefore, when the first and second members undergo the same deformation, the ratio of stresses generated in each of the first and second members can be appropriately set. This allows for greater flexibility in selecting the materials for the first and second members and setting their thicknesses according to the stresses generated in each member. Furthermore, with this configuration, even if the deformability of a corrosion-resistant first member is improved by reducing its thickness as described above, the overall strength of the diaphragm can be adjusted to a desired strength by setting the second member to generate a stress greater than the stress generated in the first member, thereby contributing to improved durability of the diaphragm. Therefore, a diaphragm that is easy to design can be provided that maintains deformability while satisfying required member strength requirements, such as corrosion resistance, pressure resistance, and durability.

[0008] In this case, it is preferable that the rigidity of the second member is greater than the rigidity of the first member. According to this configuration, by making the rigidity of the second member greater than the rigidity of the first member, when the first member and the second member undergo the same deformation, the first member is more likely to deform than the second member, which reduces the stress generated in the first member and further makes it easier to ensure pressure resistance by the second member.

[0009] In this case, the first member is preferably made of a Ni-based alloy. According to this configuration, by using a Ni-based alloy, which is generally a highly corrosion-resistant material, the required corrosion resistance can be more easily achieved. In general, Ni-based alloys are not only difficult to process but can also be expensive. Therefore, this configuration is likely to result in lower deformability and processability of the first member compared to the second member, and higher manufacturing costs. However, as described above, in the present invention, the overall strength of the diaphragm can be achieved by increasing the stress generated in the second member, making it easier to reduce the amount of the first member used. Therefore, reducing the amount of the first member used can prevent deterioration of the diaphragm's processability and contribute to reducing the diaphragm's manufacturing costs.

[0010] Furthermore, the second member is preferably made of precipitation hardening stainless steel, which generally has high strength, and thus makes it easier to achieve the required durability (fatigue strength).

[0011] Furthermore, it is preferable that the thickness of the second member is greater than the thickness of the first member. According to this configuration, by making the thickness of the second member greater than the thickness of the first member, it is possible to reduce the amount of material used, which is generally expensive and highly corrosion-resistant. Furthermore, it is easier to make the rigidity of the second member greater than the rigidity of the first member. Therefore, when the first member and the second member undergo the same deformation, the stress generated in the second member can be greater than the stress generated in the first member. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a diaphragm that can be easily designed and that satisfies the required member strength such as corrosion resistance, pressure resistance and durability while maintaining deformability. [Brief explanation of the drawings]

[0013] [Figure 1]1 is a cross-sectional view showing a pressure switch including a diaphragm according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged cross-sectional view of region A in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The pressure switch 100 is a device that detects changes in the pressure of an object to be detected by switching the conductive state of terminals in response to changes in the pressure of the object to be detected. In this embodiment, the pressure switch 100 detects a controlled fluid flowing through a flow path 62 (described below), and constitutes a normally closed switch that is conductive when the pressure of the controlled fluid is equal to or lower than a predetermined pressure and is non-conductive when the pressure of the controlled fluid is equal to or higher than the predetermined pressure. Note that the up-down and left-right directions in the drawings correspond to the up-down and left-right directions of the pressure switch 100. The definitions of these directions are merely for convenience of explanation and do not limit the directions in the actual use state of the pressure switch 100.

[0015] The pressure switch 100 includes a microswitch 1, an actuating unit 40, a cover member 50, and a coupling member 60. The microswitch 1 includes a body 10 having an internal storage space 10a (a space separate from the fluid space). The body 10 is formed in a covered cylindrical shape that opens downward. A first metal terminal 11 and a second metal terminal 12, both made of a conductive metal material, are attached to a ceiling 10b of the body 10. The first metal terminal 11 is formed by bending a flat metal material into an L-shape. The first metal terminal 11 includes a vertical plate 11a extending along the axis L of the actuating shaft 44 (described later) and a horizontal plate 11b intersecting the vertical plate 11a. The upper end of the vertical plate 11a is inserted through the ceiling 10b of the body 10 and exposed to the outside. The horizontal plate 11b extends leftward from the lower end of the vertical plate 11a and is housed in the storage space 10a. A fixed contact 20 made of a conductive material is provided on the left end of the horizontal plate portion 11b.

[0016] The second metal terminal 12 has a plate-like shape extending in the direction of the axis L and a plate surface facing right (toward the first metal terminal 11). The second metal terminal 12 has an upper end inserted through the ceiling portion 10b of the body portion 10 and exposed to the outside, and a lower end housed within the body portion 10. A movable contact plate 30 electrically connected to the second metal terminal 12 is installed at the lower end of the second metal terminal 12. The movable contact plate 30 is a contact member that can be brought into contact with and separated from the fixed contact 20. In this embodiment, the movable contact plate 30 is formed in an L shape by bending a conductive plate member with a plate surface facing the first metal terminal 11 toward the first metal terminal 11. A vertical portion 30a of the movable contact plate 30 along the direction of the axis L is fixed to the second metal terminal 12 and extends along the plate surface of the second metal terminal 12. The lower end of the vertical portion 30a is bent toward the inside of the body portion 10, and a leaf spring portion 30b is formed at this bent portion, extending toward the first metal terminal 11. The leaf spring portion 30b is elastically deformable in the direction of the axis L, starting from the bent portion. A receiving portion 30c that curves downward is formed at the center of the leaf spring portion 30b in the left-right direction. The upper end of the operating shaft 44, which will be described later, comes into contact with and separates from the receiving portion 30c.

[0017] A movable contact 30d that can be brought into contact with and separated from the fixed contact 20 is attached to the tip of the leaf spring portion 30b. The movable contact 30d is located above the fixed contact 20 and faces the fixed contact 20 in the direction of the axis L. The movable contact 30d abuts against the fixed contact 20 in a normal state (the state shown in FIG. 1) in which the pressure of the controlled fluid is equal to or lower than a predetermined pressure. In this state, the leaf spring portion 30b is elastically deformed and inclined so that its tip is positioned upward as it approaches the first metal terminal 11, and the force that attempts to restore the movable contact 30d to its state before elastic deformation urges the movable contact 30d toward the fixed contact 20. As a result, in the pressure switch 100 in a normal state, the first metal terminal 11 and the second metal terminal 12 are electrically connected via the fixed contact 20 and the movable contact 30d.

[0018] The lower inner circumferential end of the body portion 10 is formed with a first enlarged diameter portion 10c that expands radially outward, and a second enlarged diameter portion 10d that is continuous with the lower end of the first enlarged diameter portion 10c and also expands radially outward. An operating unit 40 is installed below the microswitch 1 configured in this manner. The operating unit 40 includes a guide member 41 that fits onto the inner circumferential surface of the body portion 10. The guide member 41 is formed in a lid-like shape that closes the opening of the body portion 10. A flange 42 that protrudes radially outward is formed on the outer circumferential surface of the guide member 41, and the upward surface of the flange 42 abuts against the downward surface of the first enlarged diameter portion 10c. A guide hole 43 that penetrates the center of the guide member 41 in the direction of the axis L is formed, and an operating shaft 44 is inserted through the guide hole 43. The operating shaft 44 is formed in a rod-like shape extending in the direction of the axis L. The outer diameter of the operating shaft 44 is formed slightly smaller than the inner diameter of the guide hole 43, so that the operating shaft 44 is guided by the guide hole 43 when it moves, and moves back and forth in the direction of the axis L. The upper end of the operating shaft 44 can come into contact with and separate from the receiving portion 30c of the leaf spring portion 30b, and in the state shown in Fig. 1, the weight of the operating shaft 44 causes the lower end of the operating shaft 44 to abut against the center of the upper surface of a diaphragm 47, which will be described later.

[0019] This configuration allows the operating shaft 44 to transmit the reversal displacement of the diaphragm 47 (described later) to the movable contact plate 30 of the microswitch 1. An upper cover 45 is installed below the guide member 41. The upper cover 45 is shaped like a lid and closes the opening of the body 10. The upper cover 45 has a diameter larger than the inner diameter of the second enlarged diameter portion 10d, and the portion of its upper surface near the outer periphery abuts the lower end surface of the body 10. An opening 45a penetrating the center of the upper cover 45 in the direction of the axis L is formed, and the lower end of the operating shaft 44 is inserted through the opening 45a. The center portion of the upper cover 45 is inclined upward toward the opening 45a, and the underside of this inclined portion limits the deformation and displacement of the diaphragm 47 (described later) to a predetermined level. In other words, in addition to closing the opening of the body 10, the upper cover 45 also functions as a stopper that limits the deformation of the diaphragm 47 to a predetermined level.

[0020] An O-ring 46 is installed between the guide member 41 and the upper cover 45. The O-ring 46 is crushed by being sandwiched between the guide member 41 and the upper cover 45, and is formed into a generally flattened annular shape. The O-ring 46 is disposed within the second enlarged diameter portion 10d. The upper surface of the O-ring 46 is in close contact with the lower surface of the flange 42 of the guide member 41, and the lower surface of the O-ring 46 is in close contact with the upper surface of the upper cover 45, thereby sealing the gap between the guide member 41 and the upper cover 45. A diaphragm 47 is installed below the upper cover 45. Details of the diaphragm 47 will be described later. A lower cover 48 is installed below the diaphragm 47. The lower cover 48 includes a flange portion 48a that abuts against the underside of the diaphragm 47, an inclined surface 48b that is inclined so as to be positioned radially inward around the axis L as it extends downward from the inner end of the flange portion 48a, and a bottom plate portion 48c that extends perpendicular to the axis L from the lower end of the inclined surface 48b.

[0021] A mounting hole 48d is formed in the center of the bottom plate portion 48c, penetrating in the direction of the axis L, and a coupling member 60 is attached to the mounting hole 48d. When the coupling member 60 is attached to the mounting hole 48d, an actuation chamber 48e (fluid space) is formed inside the lower cover 48, surrounded by the diaphragm 47, the lower cover 48, and the coupling member 60. In this manner, the actuation unit 40, which is formed by the guide member 41, the upper cover 45, the O-ring 46, the diaphragm 47, and the lower cover 48, is integrated with the microswitch 1 by the cover member 50. The cover member 50 is a member that houses and connects the microswitch 1 and the actuation unit 40, and is formed into a cylindrical shape with a bottom by a bottom plate 51 and a side plate 52. The upper surface of the bottom plate 51 abuts against the bottom surface of the flange portion 48a of the lower cover 48, thereby supporting the entire actuation unit 40 facing upward.

[0022] A through-hole 51a is formed in the center of the bottom plate 51 in the direction of axis L, and an inclined surface 48b of the lower cover 48 fits into the through-hole 51a. The side plate 52 extends in the direction of axis L, and its inner surface covers the outer surfaces of the body portion 10, the upper cover 45, the diaphragm 47, and the lower cover 48. The upper end 52a of the side plate 52 is crimped to a step 10e formed on the outer peripheral surface of the body portion 10. This crimping connects the microswitch 1 and the actuating portion 40. In this state, the O-ring 46 is compressed in the direction of axis L by the lower surface of the flange 42 of the guide member 41 and the upper surface of the upper cover 45. In addition, in this state, the diaphragm 47 functions as a partition wall separating the accommodation space 10a of the body portion 10 from the actuating chamber 48e in the actuating portion 40.

[0023] A coupling member 60 is provided below the actuation unit 40. The coupling member 60 is formed in a cylindrical shape extending in the direction of the axis L. A small-diameter portion 61 having a diameter smaller than that of the remaining portions of the coupling member 60 is formed at an upper end of the coupling member 60. The small-diameter portion 61 is inserted into a mounting hole 48d of the lower cover 48 and joined to the lower cover 48 by brazing, welding, or the like. A flow path 62 through which the controlled fluid to be detected flows is formed inside the coupling member 60, and the flow path 62 is connected to the working chamber 48e. This communication ensures that the flow path 62 and the working chamber 48e are at the same pressure. Note that, although the coupling member 60 is formed as a cylindrical member in this embodiment, the present invention is not limited to this example. The coupling member 60 may be a metal-processed member of any shape formed by, for example, pressing, cutting, die-casting, forging, or the like, which is connected to a pipe through which the controlled fluid to be detected is guided.

[0024] In the pressure switch 100 configured as described above, when the pressure of the controlled fluid flowing through the flow path 62 is below a predetermined pressure, the center of the diaphragm 47 is recessed downward. In this state, the upper end of the operating shaft 44 does not abut against the receiving portion 30c of the movable contact plate 30. In this state, the movable contact 30d abuts against the fixed contact 20, establishing electrical continuity between the first metal terminal 11 and the second metal terminal 12. When the pressure of the controlled fluid rises above the predetermined pressure, the center of the diaphragm 47 reverses and becomes convex upward. The reverse displacement of the diaphragm 47 causes the upper end of the operating shaft 44 to abut against the receiving portion 30c, pushing the leaf spring portion 30b of the movable contact plate 30 upward via the receiving portion 30c. This pushing continues until the upper surface of the diaphragm 47 abuts against the center of the lower surface of the upper cover 45.

[0025] This upward force causes the leaf spring portion 30b to elastically deform upward from the bent portion, resulting in the movable contact 30d separating from the fixed contact 20. This separation causes the first metal terminal 11 and the second metal terminal 12 to be in a non-conductive state. When the pressure of the controlled fluid drops below a predetermined pressure, the diaphragm 47 reverses and displaces again, with the center recessed downward, and the operating shaft 44 separates from the receiving portion 30c. This separation returns the leaf spring portion 30b to its original state before elastic deformation, and the pressure switch 100 returns to its normal state. Through this operation, the pressure switch 100 detects changes in the pressure of the object to be detected based on the conductive and non-conductive states of the first metal terminal 11 and the second metal terminal 12.

[0026] Next, the diaphragm 47 will be described. As shown in FIG. 2, the diaphragm 47 is a partition wall that separates the space within the pressure switch 100 into an actuation chamber 48e (fluid space) and a storage space 10a (another space), and prevents the controlled fluid from entering the storage space 10a. As shown in FIG. 2, the diaphragm 47 includes a first member 47a disposed on the lower side and a second member 47b disposed on the upper side. The first member 47a is the first diaphragm provided on the actuation chamber 48e side and in contact with the controlled fluid, and is formed in an overall circular plate shape (dish shape) extending around the axis L. Here, the type of controlled fluid that the first member 47a comes into contact with varies depending on the application. For example, corrosive controlled fluids such as certain chemicals, acidic fluids, water, seawater, and corrosive oils may be used. For this reason, the first member 47a is configured to have a predetermined corrosion resistance required for at least these corrosive fluids.

[0027] The predetermined corrosion resistance refers to the length of time that the diaphragm 47 can maintain its function when repeatedly used in the presence of a controlled fluid. For example, it can be determined by whether the erosion rate, expressed as the amount of erosion divided by the period of use, falls within an acceptable range. Therefore, the predetermined corrosion resistance is preferably determined so that the diaphragm 47 can maintain its function as a partition wall while transmitting its own displacement and deformation to the movable contact plate 30 via the operating shaft 44 during the use period of the pressure switch 100. Furthermore, it is more preferable to set the predetermined corrosion resistance of the first member 47a higher than the predetermined corrosion resistance of the second member 47b. Specifically, for example, if the corrosive controlled fluid is a predetermined chemical or an acidic fluid, the first member 47a is preferably made of a Ni-based alloy, a predetermined stainless steel, or the like. Ni-based alloys are generally materials with excellent corrosion resistance, such as Inconel (registered trademark) and Hastelloy (registered trademark).

[0028] Inconel and Hastelloy are particularly highly corrosion-resistant to certain chemicals and acidic fluids. As Inconel, Inconel 600, Inconel 601, Inconel 625, and Inconel 690 are particularly preferred. As Hastelloy, Hastelloy C22 and Hastelloy C276 are particularly preferred. On the other hand, certain stainless steels are particularly highly corrosion-resistant to water, seawater, and corrosive oils. As such stainless steel, SUS316 or SUS316L is particularly preferred.

[0029] The first member 47a includes a first main body 47a1 formed in a shape with a downwardly convex center in the normal state, and a first clamping portion 47a2 extending radially outward from the outer periphery of the first main body 47a1. The first main body 47a1 is formed in a shape with its center positioned at the lowest point in the normal state. The first clamping portion 47a2 is sandwiched between a flange portion 48a of the lower cover 48 and the second member 47b, and the top surface of the flange portion 48a abuts against the bottom surface of the first clamping portion 47a2. The second member 47b is a second diaphragm provided on the housing space 10a side, has substantially the same shape as the first member 47a, is formed separately from the first member 47a, and is stacked in multiple pieces above the first member 47a. The second member 47b includes a second main body 47b1 extending around the axis X2 along the first main body 47a1, and a second clamping portion 47b2 extending radially outward from the outer periphery of the second main body 47b1.

[0030] The actuating shaft 44 is provided in contact with the center of the upper surface of the second body 47b1. The second body 47b1 is stacked on the first body 47a1 without being joined to it. In this configuration, for example, gaps may be formed in the direction of the axis L between the first body 47a1 and the second body 47b1, and between the second bodies 47b1 themselves. The diaphragm 47 configured in this manner deforms to displace the first body 47a1 upward as the pressure in the flow path 62 and the actuating chamber 48e increases from the normal state. The deformed first body 47a1 then presses the second body 47b1, deforming it so that the pressed portion is displaced upward. This displacement and deformation pushes out the actuating shaft 44, which is in contact with the second body 47b1, and moves upward.

[0031] When the diaphragm 47 deforms in this manner, the first body 47a1 and the second body 47b1 deform in the same manner as described above. However, the first body 47a1 and the second body 47b1 are separate bodies that are not joined together. Therefore, the first body 47a1 and the second body 47b1 deform independently, and stresses generated when the diaphragm 47 deforms are generated separately in the first member 47a and the second member 47b. Unlike the first member 47a, the second member 47b does not come into contact with the controlled fluid. That is, the second member 47b does not require the same corrosion resistance as the first member 47a. On the other hand, although the first member 47a is configured to have a certain corrosion resistance as described above, its durability, such as fatigue strength, is easily affected not only by the shape of the first member 47a but also by the physical properties of the first member 47a. Generally, there is a trade-off between corrosion resistance and strength (for example, yield stress), and therefore the strength of the first member 47a tends to decrease, which means that the stress that the first member 47a can tolerate tends to decrease.

[0032] This is undesirable because it reduces the durability of the diaphragm 47 of this embodiment, which must repeatedly deform to move the actuating shaft 44 back and forth along the axis L. To address this issue, it is conceivable to increase the stress that the first member 47a can tolerate by increasing the thickness A1 of the first member 47a. However, this would reduce the deformability of the first member 47a compared to before the thickness A1 was increased. In this case, the stroke (displacement) of the actuating shaft 44, which is pushed into the second member 47b via the first member 47a, is limited. This may prevent smooth switching between the conductive state and the non-conductive state, which is undesirable. Therefore, in the present invention, the rigidity of the second member 47b, which does not come into contact with the controlled fluid, is made greater than the rigidity of the first member 47a, making the first member 47a more deformable than the second member 47b and making it easier for the second member 47b to ensure pressure resistance.

[0033] Specifically, the second member 47b is preferably configured so that its rigidity (bending rigidity), which is calculated by, for example, Young's modulus × moment of inertia, is higher than that of the first member 47a. To increase the rigidity of the second member 47b compared to that of the first member 47a, the material and thickness A2 of the second member 47b may be selected so that the rigidity is greater than the rigidity obtained by multiplying the Young's modulus and thickness A1 of the first member 47a (Young's modulus × moment of inertia). For example, if the Young's modulus of the material used for the second member 47b is smaller than that of the first member 47a, the thickness A2 (plate thickness) of each second member 47b may be set to be greater than the thickness A1 (plate thickness) of the first member 47a, as shown in FIG. 2. Alternatively, multiple second members 47b may be considered as a single second member 47b, and the total thickness of the second members 47b may be set to be greater than the thickness of the first member 47a. Conversely, if the Young's modulus of the material used for the second member 47b is greater than that of the first member 47a, depending on the difference in Young's modulus between the first member 47a and the second member 47b, the rigidity of the second member 47b can be greater than that of the first member 47a, even if the thickness A2 of the second member 47b is thinner than the thickness A1 of the first member 47a. Because rigidity is expressed as Young's modulus × moment of inertia, using a material with a higher Young's modulus makes it easier to increase the rigidity of the second member 47b, thereby suppressing an increase in the thickness A2 (thinner thickness A2). A thinner thickness A2 reduces the amount of material used, which leads to cost reductions. As described above, increasing the rigidity of the second member 47b makes it easier for the second member 47b to ensure the pressure resistance of the entire diaphragm 47.

[0034] As a material that can easily increase the rigidity, stainless steels other than those listed above can be used. More specifically, it is more preferable that the second member 47b be made of a high-strength precipitation-hardened stainless steel. Using a high-strength material for the second member 47b improves the strength (fatigue strength) of the second member 47b when repeatedly deforming, thereby contributing to improving the durability of the diaphragm 47. Furthermore, as shown in FIG. 2, for example, by setting the thickness A2 of the second member 47b to be greater than the thickness A1 of the first member 47a, the rigidity of the second member 47b can be further increased compared to the rigidity of the first member 47a, which is more preferable.

[0035] Therefore, by combining the first member 47a and the second member 47b, the required strength, such as corrosion resistance, pressure resistance, and durability, can be achieved while maintaining deformability. Furthermore, when combining the first member 47a and the second member 47b, compared to a configuration in which the diaphragm 47 is made of a single material, there is less need to consider the reduction in strength, such as pressure resistance and durability, associated with improving the corrosion resistance of the first member 47a, and there is less need to consider the reduction in corrosion resistance associated with improving the strength, such as pressure resistance and durability, of the second member 47b. This allows for greater flexibility in selecting the materials for the first member 47a and the second member 47b and in setting the plate thicknesses A1 and A2. Therefore, it becomes easier to achieve both the required corrosion resistance and the required strength, such as pressure resistance and durability, of the diaphragm 47 while maintaining the deformability of the diaphragm 47. The Ni-based alloys mentioned above, which are used as materials for the first member 47a, generally have poor processability and can be relatively expensive. However, with this configuration, for example, it is easy to reduce the amount of first member 47a used by reducing the plate thickness A1 of first member 47a, thereby suppressing deterioration in the workability of diaphragm 47 and reducing manufacturing costs.

[0036] According to the above-described embodiment, by laminating the first member 47a and the second member 47b separately, stresses generated when the diaphragm 47 deforms can be generated separately in the first member 47a and the second member 47b. Therefore, when the first member 47a and the second member 47b undergo the same deformation, the ratio of the stresses generated in the first member 47a and the second member 47b can be appropriately set. This allows for greater flexibility in selecting the materials for the first member 47a and the second member 47b and in setting the plate thicknesses A1 and A2 according to the stresses generated in each member. Furthermore, according to this configuration, even when the deformability of the first member 47a, which has excellent corrosion resistance, is improved by reducing the plate thickness A1 as described above, the strength of the entire diaphragm 47 can be set to a desired strength by setting the second member 47b to generate a stress greater than the stress generated in the first member 47a. This contributes to improving the durability of the diaphragm 47. Therefore, it is possible to provide a diaphragm 47 that can be easily designed and that satisfies the required member strength such as corrosion resistance, pressure resistance, and durability while maintaining deformability.

[0037] Furthermore, according to the above-described embodiment, by making the rigidity of the second member 47b greater than the rigidity of the first member 47a, when the first member 47a and the second member 47b undergo the same deformation, the first member 47a is more likely to deform than the second member 47b, which reduces the stress generated in the first member 47a and further makes it easier to ensure pressure resistance strength with the second member 47b.

[0038] Furthermore, according to the above-described embodiment, by constructing the first member 47a using a Ni-based alloy, which is generally a highly corrosion-resistant material, it is possible to more easily achieve the required corrosion resistance. In general, Ni-based alloy materials are expensive and have poor workability. Therefore, this configuration may result in lower deformability and workability of the first member 47a compared to the second member 47b, and higher manufacturing costs. However, as described above, in the present invention, the overall strength of the diaphragm 47 can be achieved as desired by increasing the stress generated in the second member 47b, which makes it easier to reduce the amount of the first member 47a used. Therefore, reducing the amount of the first member 47a used prevents deterioration in the workability of the diaphragm 47 and contributes to reducing the manufacturing costs of the diaphragm 47.

[0039] Furthermore, according to the above-described embodiment, by forming the second member 47b using precipitation hardening stainless steel, which generally has high strength, it is possible to more easily achieve the required durability (fatigue strength).

[0040] Furthermore, according to the above-described embodiment, by making the thickness A2 of the second member 47b greater than the thickness A1 of the first member 47a, it is possible to reduce the amount of material used, which is generally expensive and highly corrosion-resistant. Furthermore, it is easier to make the rigidity of the second member 47b greater than the rigidity of the first member 47a. Therefore, when the first member 47a and the second member 47b undergo the same deformation, the stress generated in the second member 47b can be greater than the stress generated in the first member 47a.

[0041] The above-described embodiments merely illustrate typical aspects of the present invention, and the present invention is not limited thereto. For example, in this embodiment, it is preferable that the second member 47b be made of a material having higher rigidity than the first member 47a, such as Inconel, and that the thickness A2 of the second member 47b be set to be greater than the thickness A1 of the first member 47a. However, if a suitable material is available that has the required deformability, corrosion resistance, or member strength, the second member 47b may be made of a material having higher rigidity than the first member 47a, and the thicknesses A2 and A1 may be the same. In this case, the thickness A2 may be smaller than the thickness A1.

[0042] Furthermore, the materials of the first member 47a and the second member 47b constituting the diaphragm 47 are not limited to metal materials. Taking into consideration the above-mentioned deformability, corrosion resistance, and member strength, the first member 47a and the second member 47b can be made of various materials, such as resin materials, rubber materials, and glass materials, or by combining various materials. In addition, in this embodiment, one first member 47a and multiple second members 47b are used, but this is not limiting. Multiple first members 47a may be used, and one second member 47b may be used. That is, one or more first members 47a and one second member 47b may be used. In addition, when a plurality of first members 47a and a plurality of second members 47b are used and the thickness A2 of the second members 47b is made larger than the thickness A1 of the first members 47a, the plurality of first members 47a may be regarded as one first member 47a and the plurality of second members 47b may be regarded as one second member 47b. In this case, the total thickness of the second members 47b may be set to be larger than the total thickness of the first members 47a.

[0043] Furthermore, in this embodiment, the pressure switch 100 is exemplified as a normally closed switch. However, the diaphragm 47 may be applied to various pressure switches, such as a normally open pressure switch that is normally non-conductive. Furthermore, the diaphragm 47 may be applied to a valve device that constitutes part of a refrigeration cycle or the like, in addition to a pressure switch. Specifically, the diaphragm 47 may be applied to an electric valve or solenoid valve having an electromagnetic coil, a mechanical expansion valve as a throttling device, or a mechanical pressure regulating valve that drives a pressure-sensitive member connected to a valve member in response to pressure fluctuations. In this case, the diaphragm 47 may be used as a member that deforms or displaces in response to pressure fluctuations of a fluid, for example, to drive a valve element. [Explanation of symbols]

[0044] 10a Containment space (separate space) 48e Working chamber (fluid space) 47 Diaphragm 47a First member 47b Second member

Claims

1. A diaphragm that separates a fluid space through which a fluid flows and another space separate from the fluid space, a first member provided on the fluid space side; a second member provided on the separate space side, the first member has a predetermined corrosion resistance at least to the fluid; the second member is made of a material different from that of the first member, A diaphragm characterized in that the first member and the second member are laminated as separate members.

2. 2. The diaphragm according to claim 1, wherein the second member has a stiffness greater than the stiffness of the first member.

3. 3. The diaphragm according to claim 2, wherein the first member is made of a Ni-based alloy.

4. 3. The diaphragm according to claim 2, wherein the second member is made of precipitation hardening stainless steel.

5. The diaphragm according to claim 1 , wherein the second member has a thickness greater than the thickness of the first member.

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