Bolt fastening structure, bolt fastening method, and flow control device
The bolt fastening structure with a gap between the shaft and inner surface addresses the issue of particle-induced leakage by containing particles, ensuring reliable fluid handling and accurate flow control in devices like mass flow controllers.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- HORIBA STEC CO LTD
- Filing Date
- 2022-01-26
- Publication Date
- 2026-06-03
AI Technical Summary
The generation of particles during bolt fastening in fluid handling devices leads to external fluid leakage due to the rubbing of threads and grooves, which has not been adequately addressed in existing technologies.
A bolt fastening structure with a shaft portion having screw threads and a receiving portion with a screw groove that maintains a gap between the inner surface and the shaft, containing particles generated during fastening, thereby reducing external fluid leakage.
The proposed structure effectively contains particles generated during fastening, minimizing the risk of fluid leakage and ensuring accurate flow control by maintaining a gap between the shaft and inner surface, thus enhancing the reliability of fluid handling systems.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a bolt fastening structure, a bolt fastening method, and a flow rate control device.
Background Art
[0002] Conventionally, an integrated gas control device equipped with a mass flow controller or the like has been proposed (see, for example, Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In a device that handles a fluid such as a gas, a plurality of block bodies each having a fluid flow path portion can be fastened using bolts to connect the flow path portions of each block. For example, the shaft portion of a bolt is inserted into a through hole provided in one block body. When the shaft portion is inserted into the other block body while rotating the bolt, the thread provided on the surface of the shaft portion meshes with the thread groove formed in the other block body and is fixed. As a result, the plurality of block bodies are fastened, and at the same time, the flow path portions of each block are connected.
[0005] However, when the bolt is rotated during the fastening process, the threads on the bolt shaft come into contact with the thread grooves and rub against them, which can cause a portion of the thread surface to break off. The broken fragments (hereinafter also referred to as particles) may include, for example, plating or other surface treatments applied to the surface of the bolt threads for corrosion resistance and gloss, and these may consist of plating flakes that have peeled off from the surface of the threads. If the surface of the bolt threads is not surface-treated, the particles may consist of fragments of the metal itself that makes up the threads. If the generated particles get stuck between the fastened blocks, creating a gap, the fluid flowing through the channel will leak to the outside through this gap.
[0006] As long as the threads and grooves of the bolt come into contact and rub against each other during fastening, the generation of the aforementioned particles is unavoidable. However, no measures to reduce external fluid leakage caused by the generated particles have been considered to date, including in Patent Document 1.
[0007] The present invention was made to solve the above-mentioned problems, and its objective is to provide a bolt fastening structure, a bolt fastening method, and a flow rate control device that can reduce external fluid leakage caused by particles generated during bolt fastening. [Means for solving the problem]
[0008] A bolt fastening structure according to one aspect of the present invention is a bolt fastening structure used in a flow control device or a flow control system, comprising a bolt, a block body, and a fastened object fastened to the block body by the bolt, wherein the bolt has a shaft portion having screw threads on its outer circumference, the fastened object has a through hole through which the shaft portion passes, the block body has a receiving portion for receiving the shaft portion inserted through the through hole, a body-side opening, and a body-side passage portion which is a fluid passage connected to the body-side opening, wherein the body-side opening is located on the same plane as the receiving portion when viewed from the fastened object side, the receiving portion has a screw groove that contacts and engages with the screw threads of the shaft portion, and an inner surface located upstream of at least a portion of the screw groove in the insertion direction of the shaft portion, the inner surface is located away from the shaft portion inserted into the receiving portion with a gap between them.
[0009] A flow control device according to another aspect of the present invention comprises the bolted fastening structure described above, a flow detection mechanism for detecting the flow rate of the fluid flowing inside the bolted fastening structure, a flow control valve, and a drive control unit for driving the flow control valve based on the detection result of the flow detection mechanism.
[0010] A bolt fastening method according to yet another aspect of the present invention comprises a passing step of inserting and passing the shaft portion of a bolt having threads on its outer circumferential surface into a through hole of a workpiece, and a fastening step of inserting the shaft portion that has passed through the through hole into a receiving portion of a block body having an inner surface and thread grooves located at a distance from the inserted shaft portion with a gap between them, and fastening the workpiece and the block body by engaging the threads of the bolt with the thread grooves of the receiving portion. [Effects of the Invention]
[0011] According to the present invention, it is possible to reduce external fluid leakage caused by particles generated during bolt fastening. [Brief explanation of the drawing]
[0012] [Figure 1]It is an explanatory diagram showing the configuration of a flow rate control device according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view showing an enlarged flow rate control valve included in the flow rate control device. [Figure 3] It is a front view of the flow rate control device. [Figure 4] It is a perspective view when the flow rate control device in FIG. 3 is cut along a predetermined cross-section. [Figure 5] It is a perspective view when the structure is cut along a predetermined cross-section. [Figure 6] It is a perspective view of the block body included in the structure. [Figure 7] It is a cross-sectional view showing an enlarged structure of the fastening portion of the structure. [Figure 8] It is a cross-sectional view showing the structure in FIG. 7 disassembled. [Figure 9] It is a figure showing together a plan view and a cross-sectional view of the receiving portion of the structure. [Figure 10] It is a figure showing together the configuration of a modified example of the structure in a plan view and a cross-sectional view. [Figure 11] It is a cross-sectional view showing the configuration of another modified example of the structure. [Figure 12] It is a cross-sectional view showing the configuration of a further modified example of the structure. [Figure 13] It is a cross-sectional view showing the configuration of a further modified example of the structure. [Figure 14] It is a cross-sectional view showing the configuration of a further modified example of the structure. [Figure 15] It is a perspective view showing a schematic configuration of a flow rate control system including the flow rate control device.
Embodiments for Carrying Out the Invention
[0013] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.
[0014] 〔1. Outline of the Flow Rate Control Device〕 FIG. 1 is an explanatory diagram showing a schematic configuration of a flow rate control device 1 according to the present embodiment. The flow rate control device 1 is constituted by, for example, a mass flow controller. The mass flow controller is used, for example, in a semiconductor manufacturing apparatus and is a device that controls the flow rate of a fluid such as a gas used in the semiconductor manufacturing process. The flow rate control device 1 includes a main body portion 2, a flow rate detection mechanism 3, a flow rate control valve 4, and a drive control portion 5.
[0015] The main body portion 2 is a block having a flow path portion 21 inside. The above-mentioned fluid flows through the flow path portion 21. The main body portion 2 is constituted by a structure 100b (see FIG. 3) as a bolt fastening structure 100 described later. The details of the main body portion 2 are as follows.
[0016] The main body portion 2 includes a plurality of block bodies. The plurality of block bodies include a first block body L1, a second block body L2, and a third block body L3. The first block body L1, the second block body L2, and the third block body L3 are arranged in this order from the fluid inflow side to the outflow side. And adjacent block bodies are fastened by bolts. That is, the first block body L1 and the second block body L2 are fastened by a bolt B1 (see FIG. 4). Also, the second block body L2 and the third block body L3 are fastened by a bolt B2 (see FIG. 4).
[0017] An inflow path 21a that constitutes a part of the flow path portion 21 is provided in the first block body L1. An outflow path 21b that constitutes a part of the flow path portion 21 is provided in the third block body L3. In the example of FIG. 1, the inflow path 21a and the outflow path 21b are each bent in shape, but their respective shapes are not particularly limited and may be linear.
[0018] The second block L2 is provided with an intermediate channel 21c and a bypass section 21d, which constitute part of the flow path section 21. The intermediate channel 21c and the bypass section 21d are connected inside the second block L2. Furthermore, when the first block L1 and the second block L2 are connected, the inflow passage 21a and the bypass section 21d are connected. Moreover, when the second block L2 and the third block L3 are connected, the intermediate channel 21c and the outflow passage 21b are connected. Therefore, when the first block L1, the second block L2, and the third block L3 are connected, the inflow passage 21a and the outflow passage 21b are connected via the bypass section 21d and the intermediate channel 21c.
[0019] An upstream port 2A is located at the upstream end of the flow channel 21 (particularly the inlet channel 21a). The upstream port 2A is connected to an external inlet pipe (not shown). A downstream port 2B is located at the downstream end of the flow channel 21 (particularly the outlet channel 21b). The downstream port 2B is connected to an external outlet pipe (not shown).
[0020] The bypass section 21d described above is connected to an inlet channel 22a and an outlet channel 22b. The inlet channel 22a and the outlet channel 22b are connected to one end and the other end of the thin tube 31 of the flow detection mechanism 3, respectively.
[0021] Therefore, the fluid that flows from the external inflow piping through the upstream port 2A into the inflow passage 21a branches into the inlet passage 22a and the bypass section 21d at a predetermined flow rate ratio. The fluid that flows through the inlet passage 22a and the narrow tube 31 of the flow detection mechanism 3 is guided to the bypass section 21d via the outlet passage 22b and merges with the fluid flowing in the bypass section 21d. After merging, the fluid flows from the bypass section 21d towards the intermediate passage 21c.
[0022] The flow detection mechanism 3 detects the flow rate of the fluid flowing through the main body 2. In this embodiment, the flow detection mechanism 3 employs a thermal method for detecting the fluid flow rate. Specifically, the flow detection mechanism 3 comprises the thin tube 31 and a pair of heating resistance wires 32 and 33. The thin tube 31 passes through a through hole T provided in the fourth block body L4. The fourth block body L4 is fastened to the second block body L2 by bolts B3 (see Figures 3 and 4). The heating resistance wires 32 and 33 are wound around the thin tube 31 and connected to bridge circuits (not shown), respectively.
[0023] When current is passed through the heating resistors 32 and 33, and fluid is flowed through the tube 31 while the heating resistors 32 and 33 are heated, a temperature difference corresponding to the mass flow rate of the fluid is generated on the upstream and downstream sides of the tube 31. By converting this temperature difference into an electrical signal using the bridge circuit described above, the mass flow rate of the fluid can be measured (detected). The calculation unit for measuring the mass flow rate of the fluid, that is, the calculation unit CA including the bridge circuit described above, may be included in the drive control unit 5, which will be described later.
[0024] The flow detection mechanism 3 may also be configured to detect the fluid flow rate using a method other than the thermal method (for example, a pressure type (differential pressure type)).
[0025] Figure 2 is an enlarged cross-sectional view showing the flow control valve 4. The flow control valve 4 is a mechanism that controls the flow rate of fluid flowing inside the main body 2, and is configured as a normally closed type, for example. Such a flow control valve 4 is composed of a valve seat 41, a valve body 42, an actuator 43, an actuator 44, a retaining member 45, a spring support base 46, a valve body return spring 47, a return spring support part 48, and a biasing member 49.
[0026] The valve seat portion 41 has a substantially rotating shape and has a valve seat surface 41S at its lower end. An internal flow path 41a, which serves as a fluid flow path, is formed inside the valve seat portion 41.
[0027] The valve seat portion 41 is housed in a cylindrical receiving recess L2a formed in the main body portion 2 (particularly the second block body L2). The receiving recess L2a divides the intermediate flow path 21c in the second block body L2. Of the intermediate flow path 21c divided by the receiving recess L2a, the upstream flow path is referred to as the first intermediate flow path 21c1, and the downstream flow path is referred to as the second intermediate flow path 21c2. The first intermediate flow path 21c1 is connected to an opening provided in the center of the bottom surface of the receiving recess L2a. The second intermediate flow path 21c2 is connected to an opening provided on the periphery or side of the bottom surface of the receiving recess L2a.
[0028] When the valve seat portion 41 is housed in the housing recess L2a, a gap is formed between the outer circumferential surface of the valve seat portion 41 and the inner circumferential surface of the housing recess L2a. The second intermediate flow path 21c2 communicates with the internal flow path 41a through this gap.
[0029] The valve body 42 is located below the valve seat portion 41 within the housing recess L2a and is positioned opposite the valve seat portion 41. The valve body 42 has a substantially rotating shape and has a seating surface 42S on its upper part. The seating surface 42S contacts or separates from the valve seat surface 41S as the valve body 42 moves in the vertical direction.
[0030] The valve body 42 is biased upward by the valve body return spring 47, that is, in the direction in which the seating surface 42S contacts (seats) the valve seat surface 41S. The valve body return spring 47 is supported by a return spring support portion 48. The return spring support portion 48 is located below the valve seat portion 41 within the housing recess L2a, and supports both the valve body return spring 47 and the valve seat portion 41.
[0031] The actuator 43 is a drive unit that drives the valve body 42 in the vertical direction, that is, in the direction of contact and separation of the seating surface 42S with respect to the valve seat surface 41S, via the shaft 441 of the actuator 44. This actuator 43 includes, for example, a piezo stack 431. The piezo stack 431 is formed by stacking multiple piezoelectric elements that expand and deform when a voltage is applied. The piezo stack 431 is housed in a housing 432.
[0032] The actuator 44 has the shaft 441 and a support 443 (fifth block body L5) that supports the shaft 441 via a diaphragm portion 442. The support 443, together with a retaining member 45 (sixth block body L6) located above it, is fixed to the second block body L2 by bolts B4.
[0033] The retaining member 45 is a cover that presses the actuator 44 (particularly the support 443) against the main body 2 (particularly the second block L2). The spring support base 46 supports one end (lower end) of the biasing member 49. The biasing member 49 is located around the shaft 441, and its other end (upper end) is fixed to the upper end of the shaft 441.
[0034] In the configuration of the flow control valve 4 described above, when no voltage is applied to the piezo stack 431, the seating surface 42S is in contact with the valve seat surface 41S due to the upward biasing force of the valve body return spring 47. As a result, the first intermediate flow path 21c1 and the second intermediate flow path 21c2 are blocked. In other words, in this state, the fluid flowing through the first intermediate flow path 21c1 does not flow to the second intermediate flow path 21c2 via the internal flow path 41a of the valve body 41.
[0035] When a voltage is applied to the piezo stack 431, the piezo stack 431 expands. As a result, the piezo stack 431 pushes the shaft 441 of the actuator 44 downward against the biasing force of the biasing member 49. This causes the valve body 42 to move downward. That is, the seating surface 42S of the valve body 42 separates from the valve seat surface 41S, and a gap corresponding to the applied voltage is formed between the seating surface 42S and the valve seat surface 41S. In this state, the fluid flowing through the first intermediate flow path 21c1 flows into the internal flow path 41a of the valve body 41 through the gap, and then flows into the second intermediate flow path 21c2.
[0036] In this way, the actuator 43 (especially the piezo stack 431) drives the seating surface 42S of the valve body 42 to move toward and away from the valve seat surface 41S of the valve seat portion 41. By applying a voltage (opening control signal) corresponding to the desired valve opening to the actuator 43 and extending the actuator 43 (piezo stack 431), a valve opening corresponding to the value of the opening control signal can be achieved, thereby adjusting (controlling) the flow rate of the fluid flowing from the inlet passage 21a through the intermediate passage 21c to the outlet passage 21b.
[0037] The drive control unit 5 drives the actuator 43 of the flow control valve 4 by providing the above-mentioned opening control signal to the actuator 43 of the flow control valve 4 based on the detection result (detected flow rate) of the flow detection mechanism 3. Such a drive control unit 5 is composed of (1) an amplification circuit that amplifies the output signal of the bridge circuit, (2) a correction circuit that corrects the output signal of the amplification circuit and outputs it to the outside of the flow control device 1, (3) a comparison control circuit that compares the corrected signal with a flow rate setting signal input from the outside, (4) a drive circuit that generates a drive signal (opening control signal) for the actuator 43 based on the output of the comparison control circuit, and (5) a control unit (e.g., CPU). By driving the actuator 43, the drive control unit 5 can adjust the valve opening as described above and bring the flow rate of the fluid flowing through the flow path section 21 (especially the outflow passage 21b) closer to a predetermined set flow rate.
[0038] [2. Regarding bolted fastening structures] Figure 3 is a front view of the flow control device 1 described above. The flow control device 1 includes a bolted structure 100. The bolted structure 100 includes, for example, at least one of structures 100a and 100b. Structure 100a is constructed by fastening the fourth block body L4 and the second block body L2 with bolts B3, and fastening the actuator 44 (particularly the support 443), which is the fifth block body L5, and the retaining member 45, which is the sixth block body L6, to the second block body L2 with bolts B4.
[0039] Here, if the second block body L2 is considered the block body 200, then the fourth block body L4 can be called the fastened object 300 that is fastened to the block body 200 by bolt B3. Also, the fifth block body L5 and the sixth block body L6 can be collectively (as a single unit) called the fastened object 300 that is fastened to the block body 200 by bolt B4. Therefore, the structure 100a comprises bolt B3, the second block body L2 as the block body 200, and the fourth block body L4 as the fastened object 300. Furthermore, the structure 100a comprises bolt B4, the second block body L2 as the block body 200, and the fifth block body L5 and the sixth block body L6 as the fastened objects 300.
[0040] Figure 4 is a perspective view of the flow control device 1 shown in Figure 3, cut through a section passing through bolts B3 and B4. As shown in the figure, the structure 100b is constructed by fastening the first block body L1 and the second block body L2 with bolt B1, and fastening the second block body L2 and the third block body L3 with bolt B2.
[0041] Here, as described above, if the second block body L2 is the block body 200, then the first block body L1 can be called the fastened object 300 that is fastened to the block body 200 by bolt B1. Similarly, the third block body L3 can be called the fastened object 300 that is fastened to the block body 200 by bolt B2. Therefore, the structure 100b comprises bolts B1 and B2, the second block body L2 as the block body 200, and the first block body L1 and the third block body L3 as the fastened objects 300.
[0042] The details of the bolted fastening structure 100 will be described below. Note that structures 100a and 100b, which constitute the bolted fastening structure 100, have the same fastening structure, differing only in the type of fastened object 300. Therefore, the fastening structure of structure 100a will be described here as an example.
[0043] Furthermore, in structure 100a, two fastened members 300, namely a fastened member 300 consisting only of the fourth block body L4 and a fastened member 300 consisting of the fifth block body L5 and the sixth block body L6, are fastened to the second block body L2, which is the block body 200. However, the fastening structure of each fastened member 300 to the block body 200 is the same. Therefore, as an example, the fastening structure of the fourth block body L4 to the second block body L2 will be described here.
[0044] Figure 5 is a perspective view of the structure 100a, cut in a cross-section passing through two bolts B3 and perpendicular to the direction of connection between the second block body L2 and the third block body L3. The fourth block body L4 is fastened to the second block body L2 by four bolts B3. Each bolt B3 has a head 101 and a shaft portion 102. The head 101 has a larger diameter than the shaft portion 102. The head 101 and the shaft portion 102 are connected in the axial direction (direction of the central axis) of the shaft portion 102. The other bolts B1, B2 and B4 have the same structure as bolt B3.
[0045] The fourth block L4 (the fastened object 300) has a through hole 301. The shaft portion 102 of the bolt B3 is located passing through the through hole 301.
[0046] The second block body L2 (block body 200) has a receiving portion 201. The receiving portion 201 receives the shaft portion 102 which is inserted through the through hole 301.
[0047] The second block body L2 further has a receiving section 201a. As shown in Figure 4, the receiving section 201a receives the shaft portion 102 of the bolt B1 inserted through the through hole 301 of the first block body L1. Similarly, the second block body L2 further has receiving sections 201b and 201c. The receiving section 201b receives the shaft portion 102 of the bolt B2 inserted through the through hole 301 of the third block body L3. The receiving section 201c receives the shaft portion 102 of the bolt B4 inserted through the through hole 301 that penetrates the fifth block body L5 and the sixth block body L6. These receiving sections 201a to 201c have the same structure as the receiving section 201.
[0048] As shown in Figure 5, the structure 100a is equipped with a sealing material S. The sealing material S is composed of, for example, an annular gasket and is positioned in contact with the second block body L2, which is the block body 200, and also in contact with the fourth block body L4, which is the object to be fastened 300. The sealing material S has an opening Sa. When viewed from the object to be fastened 300 side, that is, from the fourth block body L4 side, the sealing material S is positioned on the same plane (side by side) with the receiving portion 201. The direction in which the sealing material S and the receiving portion 201 are aligned is perpendicular to the insertion direction of the shaft portion 102 into the receiving portion 201.
[0049] Figure 6 is a perspective view of the second block body L2. The second block body L2, which is the block body 200, is provided with a seal material receiving portion 202. The seal material receiving portion 202 is a recess that receives (or accommodates) a seal material S. The seal material receiving portion 202 is provided, for example, at positions corresponding to the inlet side flow path 22a and the outlet side flow path 22b of the second block body L2. For the convenience of the following explanation, when distinguishing between the two seal material receiving portions 202, one seal material receiving portion 202 provided corresponding to the inlet side flow path 22a will be referred to as seal material receiving portion 202a, and the other seal material receiving portion 202 provided corresponding to the outlet side flow path 22b will be referred to as seal material receiving portion 202b.
[0050] The seal material receiving portion 202a has a main body side opening 202a1. The inlet side flow path 22a constitutes a main body side passage, which is a fluid passage connected to the main body side opening 202a1. Similarly, the seal material receiving portion 202b has a main body side opening 202b1. The outlet side flow path 22b constitutes a main body side passage, which is a fluid passage connected to the main body side opening 202b1.
[0051] As shown in Figure 5, the inlet-side flow path 22a of the second block body L2 and the thin tube 31 located in the through hole T of the fourth block body L4 are in communication through the opening Sa of the seal material S housed in the seal material receiving section 202a. As a result, the fluid passing through the inlet-side flow path 22a flows through the opening Sa of the seal material S into the thin tube 31. From this, it can be said that the second block body L2 has an inlet-side flow path 22a that serves as a fluid passage connected to the opening Sa of the seal material S. Similarly, it can be said that the fourth block body L4 has a thin tube 31 that serves as a fluid passage connected to the opening Sa of the seal material S. In the seal material receiving section 202, the seal material S is located around the main body-side opening 202a1 and the main body-side opening 202b1 (see Figure 6), respectively.
[0052] Furthermore, the thin tube 31 communicates with the outlet-side flow path 22b of the second block body L2 through the opening of the seal material housed in the other seal material receiving portion 202b. As a result, the fluid flowing through the thin tube 31 flows through the opening of the seal material to the outlet-side flow path 22b. From this, it can be said that the second block body L2 has an outlet-side flow path 22b which serves as a fluid passage connected to the opening of the seal material.
[0053] The second block body L2 is also provided with other seal material receiving portions 202c, etc. These other seal material receiving portions 202c etc. accommodate seal material that contacts both the second block body L2 and other fastened bodies 300 (for example, the first block body L1, the second block body L2, and the fifth block body L5). As a result, for example, fluid flowing from the inlet passage 21a of the first block body L1 toward the bypass portion 21d of the second block body L2 flows through the opening of the seal material housed in the other seal material receiving portion 202c. Also, fluid flowing from the first intermediate passage 21c1 of the second block body L2 toward the second intermediate passage 21c2 flows through the opening of the seal material housed in the other seal material receiving portion 202d. Furthermore, fluid flowing from the intermediate passage 21c of the second block body L2 toward the outlet passage 21b of the third block body L3 flows through the opening of the seal material housed in other seal material receiving portions (not shown).
[0054] In this respect as well, the second block body L2 can be said to have a fluid passage (for example, a bypass section 21d, an intermediate passage 21c) that connects to the opening of the seal material housed in the seal material receiving section 202c, etc. Similarly, the first block body L1 as the fastened body 300 can be said to have an inlet passage 21a as the passage, and the third block body L3 can be said to have an outlet passage 21b as the passage.
[0055] The seal material receiving portion described above may be provided only on the fastened object 300 side, or it may be provided on both the block body 200 and the fastened object 300. In this embodiment, the second block body L2, which is the block body 200, is provided with a seal material receiving portion 202, and the fourth block body L4, which is the fastened object 300, is also provided with a seal material receiving portion 302 (see Figures 5 and 7). The seal material receiving portion 302 sandwiches the same seal material S between itself and the seal material receiving portion 202.
[0056] As shown in Figure 5, the seal material receiving portion 302 has a fastening-side opening 302a. The thin tube 31 constitutes a fastening-side passage portion, which is a fluid passage connected to the fastening-side opening 302a.
[0057] Figure 7 is an enlarged cross-sectional view showing the structure of the fastening portion of the structure 100a by the bolt B3. Figure 8 is an exploded cross-sectional view showing the above structure of the structure 100a. Figure 9 is a diagram showing both a plan view and a cross-sectional view of the receiving portion 201. As shown in these figures, the shaft portion 102 of the bolt B3 has threads 102b on its outer circumferential surface 102a. The threads 102b are formed in a spiral shape on the outer circumferential surface 102a.
[0058] Here, for the sake of convenience in the following explanation, the insertion direction of the shaft portion 102 into the receiving portion 201 will be defined as the direction along the central axis CA of the shaft portion 102. The direction around the central axis CA of the shaft portion 102 will be referred to as the circumferential direction, and the direction intersecting the central axis CA in a plane perpendicular to the central axis CA of the shaft portion 102 will be referred to as the radial direction. According to this definition, for example, the outer circumferential surface 102a of the shaft portion 102 can also be said to be a surface along the circumferential direction of the shaft portion 102.
[0059] The receiving portion 201 of the second block body L2 has a screw groove 211a and an inner surface 211b. The screw groove 211a is formed in a helical shape and, when the bolt B3 is rotated, contacts and engages with the threads 102b of the shaft portion 102 that passes through the inside of the receiving portion 201.
[0060] The inner surface 211b is located upstream of at least a portion of the screw groove 102a in the insertion direction of the shaft portion 102. In the example shown in Figures 7 to 9, the inner surface 211b is located upstream of the entire screw groove 102a in the insertion direction of the shaft portion 102. The inner surface 211b is located away from the shaft portion 102 inserted into the receiving portion 201, with a gap G between them. As shown in Figure 7, the distance D between the central axis CA of the shaft portion 102 and the inner surface 211b is constant in the insertion direction of the shaft portion 102, but may vary in the insertion direction. The latter example will be described later.
[0061] The inner surface 211b is positioned to surround the shaft portion 102 in the circumferential direction. That is, the inner surface 211b is positioned along the entire circumference of the shaft portion 102 inserted into the receiving portion 201. The upstream end of the screw groove 211a and the downstream end of the inner surface 211b are connected by the bottom surface 211c. The bottom surface 211c is a surface positioned along the radial direction of the shaft portion 102 and is formed in an annular shape in the circumferential direction of the central axis CA of the shaft portion 102.
[0062] When fastening the fourth block body L4 (the object to be fastened 300) to the second block body L2 (the block body 200) using bolt B3, as shown in Figure 8, with the sealant S placed in the sealant receiving portion 202 of the second block body L2, the fourth block body L4 is superimposed on the second block body L2 and the fastening position is aligned.
[0063] Next, the shaft portion 102 of bolt B3 is inserted into the through hole 301 of the fourth block body L4 and passed through (passing process). Then, the shaft portion 102 that has passed through the through hole 301 is inserted into the receiving portion 201 of the second block body L2. In the receiving portion 201, the shaft portion 102 of bolt B3 passes inside the inner surface 211b and reaches the upstream end of the screw groove 211a.
[0064] In this state, when bolt B3 is rotated, the threads 102b of the shaft portion 102 come into contact with the thread groove 211a and engage, causing bolt B3 to advance downstream. When the head 101 of bolt B3 comes into contact with the fourth block body L4, the rotation of bolt B3 stops. With this, the fourth block body L4 is fastened (fixed) to the second block body L2 (fastening process).
[0065] In this embodiment, the inner surface 211b of the receiving portion 201 is located away from the inserted shaft portion 102 via a gap G. As a result, even if the threads 102b of the shaft portion 102 come into contact with and rub against the thread groove 211a of the receiving portion 201, causing fine fragments (such as metal pieces like plating) to peel off from the threads 102b, these peeled-off metal pieces (hereinafter referred to as particles) are contained in the gap G formed upstream of the thread groove 211a. Therefore, the scattering of particles generated during the fastening process to the outside can be reduced. Thus, as shown in Figure 5, even if the main body side opening 202a1 of the seal material receiving portion 202 is located on the same plane (side by side) as the receiving portion 201 when viewed from the fourth block body L4 side, the risk of particles getting stuck between the second block body L2 and the fourth block body L4 and forming a gap can be reduced. As a result, the risk of fluid flowing through the inlet-side channel 22a connected to the main body-side opening 202a1 leaking to the outside through the gap can be reduced. In other words, the risk of fluid leaking to the outside due to the particles can be reduced.
[0066] In particular, since the inner surface 211b is located upstream of the entire screw groove 211a, the inner surface 211b can be positioned upstream of the screw groove 211a so as to surround the entire circumferential direction of the inserted shaft portion 102 with a gap G in between. This allows for the formation of an annular groove between the shaft portion 102 and the inner surface 211b. In other words, a space for accommodating particles can be secured around the entire circumferential direction of the shaft portion 102.
[0067] Furthermore, since the inner surface 211b is positioned along the entire circumference of the inserted shaft portion 102, the annular groove described above can be formed around the shaft portion 102. Therefore, when fastening, particles can be dealt with regardless of the position or direction from which they are scattered along the circumferential direction of the shaft portion 102. In other words, no matter where particles are generated from the threads 102b of the shaft portion 102, the generated particles can be contained in the annular groove, reducing their scattering to the outside.
[0068] Furthermore, the fourth block body L4 has a fastened-side opening 302a and a narrow tube 31 as a fastened-side passage. The inlet-side passage 22a, which serves as a main body-side passage, is connected to the narrow tube 31 via the main body-side opening 202a1 and the fastened-side opening 302a. In this configuration, fluid flows from the inlet-side passage 22a of the second block body L2 to the narrow tube 31 of the fourth block body L4. In a configuration where fluid flows inside between the second block body L2 and the fourth block body L4, if particles get stuck between the second block body L2 and the fourth block body L4 during fastening, forming a gap, external fluid leakage is likely to occur. Therefore, the configuration of this embodiment, which reduces external fluid leakage caused by particles, is very effective.
[0069] Furthermore, in this embodiment, as shown in Figure 5, the sealing material S is positioned around the opening 202a1 on the main body side. In this embodiment, as described above, the scattering of particles generated during the fastening process to the outside can be reduced, thus reducing the risk of the particles interfering with (getting caught in) the sealing material S and damaging the sealing material S. As a result, the risk of fluid leaking to the outside through the sealing material S can be reduced.
[0070] Furthermore, the flow control device 1 shown in Figure 1, etc., comprises a structure 100a as the bolt fastening structure 100 described above, a flow detection mechanism 3, a flow control valve 4, and a drive control unit 5. With the configuration of the structure 100a described above, the risk of leakage to the outside of the fluid due to particles generated during fastening can be reduced, so that flow control based on flow detection can be performed with high accuracy.
[0071] Furthermore, in the bolt fastening method of this embodiment, in the fastening step described above, the shaft portion 102 that has passed through the through hole 301 of the fourth block body L4 is inserted into the receiving portion 201 of the second block body L2, which has an inner surface 211b and a screw groove 211a located away from the inserted shaft portion 102 via a gap G, and the fourth block body L4 and the second block body L2 are fastened by engaging the screw threads 102b of the bolt B3 with the screw groove 211a of the receiving portion 201. As a result, particles generated by the engagement of the screw threads 102b and the screw groove 211a are contained in the gap G between the inner surface 211b and the shaft portion 102 in the receiving portion 201, thereby reducing the scattering of the particles to the outside. As a result, the risk of particles getting stuck between the second block body L2 and the fourth block body L4 and forming a gap during fastening is reduced. Therefore, the risk of fluid leaking to the outside through the gap is reduced.
[0072] [3. Variant Example] Figure 10 shows a modified configuration of the structure 100a, including both a plan view and a cross-sectional view. The inner surface 211b of the receiving portion 201 may be located upstream of a portion of the screw groove 211a in the insertion direction of the shaft portion 102. The portion of the screw groove 211a corresponds to a portion of the angular range in the 360° rotation direction of the bolt B3. In this case, the inner circumferential surface 211b will be located along only a portion of the circumferential direction of the inserted shaft portion 102, rather than the entire circumference.
[0073] In this case, it is desirable that the inner surface 211b is positioned across the region R (hatched area) between the screw groove 211a and the sealing material S when viewed from the fourth block body L4 side.
[0074] In the configuration shown in Figure 10, particles generated from the threads 102b of the shaft portion 102 of the bolt B3 during fastening, specifically those particles that scatter in the direction of the sealing material S, can be contained within the gap G between the shaft portion 102 and the inner surface 211b. Therefore, with a minimal configuration that positions the inner circumferential surface 211b along only a portion of the circumferential direction of the shaft portion 102 inserted into the receiving portion 201, the risk of external leakage due to particles can be reduced.
[0075] Furthermore, in the configuration shown in Figure 9, that is, in the configuration where the inner surface 211b of the receiving portion 201 is located upstream of the entire screw groove 211a, it is clear that the inner surface 211b is located across region R. In other words, the configuration in which the inner surface 211b is located across region R is not limited to the configuration in which the inner surface 211b is located upstream of a portion of the screw groove 211a.
[0076] Figure 11 is a cross-sectional view showing the configuration of another modified structure of the structure 100a. The inner surface 211b of the receiving portion 201 may have multiple side portions. In the example of Figure 11, the inner surface 201 has two side portions 211b1 and 211b2. Side portion 211b1 is located upstream of side portion 211b2 in the insertion direction of the shaft portion 102. Note that the number of side portions may be three or more.
[0077] The two side portions 211b1 and 211b2 are at different distances from the central axis CA of the shaft portion 102 inserted into the receiving portion 201. For example, if the distance between side portion 211b1 and the central axis CA is D1, and the distance between side portion 211b2 and the central axis CA is D2, then D1 > D2. That is, the multiple side portions 211b1 and 211b2 are arranged in order from the upstream side to the downstream side in the insertion direction of the shaft portion 102, with the distance from the central axis CA of the shaft portion 102 decreasing.
[0078] The lower end of side portion 211b1 (the downstream end in the insertion direction) and the upper end of side portion 211b2 (the upstream end in the insertion direction) are connected via a connecting portion 213. The connecting portion 213 is located along a direction perpendicular to the central axis CA.
[0079] As described above, even if the inner surface 211b of the receiving portion 201 has a shape in which the distance from the central axis CA gradually decreases from the upstream side to the downstream side in the insertion direction of the shaft portion 102, a particle accommodation space (gap G) can be secured between the shaft portion 102 inserted into the receiving portion 201 and the inner surface 211b, and the effects of the present embodiment described above can be obtained.
[0080] FIG. 12 is a cross-sectional view showing a configuration of a further modification of the structure 100a. The plurality of side portions 211b1 and 211b2 may be arranged in the order of increasing distance from the central axis CA of the shaft portion 102 from the upstream side to the downstream side in the insertion direction of the shaft portion 102. In the example of FIG. 12, D1 < D2. Even with such a configuration, a particle accommodation space (gap G) can be secured between the shaft portion 102 inserted into the receiving portion 201 and the inner surface 211b, and the effects of the present embodiment described above can be obtained.
[0081] FIG. 13 is a cross-sectional view showing a configuration of a further modification of the structure 100a. The inner surface 211b of the receiving portion 201 may have a tapered portion 211b3. The tapered portion 211b3 approaches the central axis CA of the shaft portion 102 from the upstream side to the downstream side in the insertion direction of the shaft portion 102 inserted into the receiving portion 201.
[0082] As described above, even if the inner surface 211b of the receiving portion 201 has a shape in which the distance from the central axis CA continuously decreases from the upstream side to the downstream side in the insertion direction of the shaft portion 102, a particle accommodation space (gap G) can be secured between the shaft portion 102 inserted into the receiving portion 201 and the inner surface 211b, and the effects of the present embodiment described above can be obtained.
[0083] Figure 14 is a cross-sectional view showing a further modified configuration of the structure 100a. The tapered portion 211b3 described above may have a shape that moves away from the central axis CA of the shaft portion 102 from the upstream side to the downstream side in the insertion direction of the shaft portion 102 inserted into the receiving portion 201. In this configuration, the downstream end of the tapered portion 211b3 and the upstream end of the screw groove 211a are connected by the bottom surface 211c. Even with this configuration, a particle containment space (gap G) can be secured between the shaft portion 102 inserted into the receiving portion 201 and the inner surface 211b, thereby obtaining the effects of this embodiment described above.
[0084] [4. Other] In the example shown in Figure 9, the inner surface 211b of the receiving portion 201 is circular when viewed from the side of the fastened object, that is, the upstream side in the bolt insertion direction. However, it may also be an ellipse, polygon, or any other shape other than circular.
[0085] The configurations shown in this embodiment may be combined as appropriate to form the bolt fastening structure 100. For example, the configuration in Figure 10, in which the inner surface 211b of the receiving portion 201 is provided on a part of the circumferential direction of the shaft portion 102, may be combined with the configuration in Figure 11 or Figure 12, in which the distance between the inner surface 211b and the central axis CA is changed in steps, to form the bolt fastening structure 100. Alternatively, the configuration in Figure 10 may be combined with the configuration in Figure 13 or Figure 14, in which the distance between the inner surface 211b and the central axis CA is changed continuously, to form the bolt fastening structure 100. Furthermore, the configuration in Figure 11 or Figure 12 may be combined with the configuration in Figure 13 or Figure 14 to form the bolt fastening structure 100.
[0086] The bolted fastening structure 100 described in this embodiment can be used in a flow control system including a flow control device 1. Figure 15 is a perspective view showing the schematic configuration of a flow control system 500. The flow control system 500 includes the flow control device 1 of this embodiment and equipment 600. Equipment 600 is composed of equipment appropriately selected from pneumatic valves, gas filters, pressure sensors, pressure regulators, bypass flanges, etc. It is also possible to configure the flow control system 500 by using multiple different types of equipment 600 in combination.
[0087] The bolt fastening structure 100 described in this embodiment can be used not only for the fastening portions of each block of the flow control device 1, but also for the fastening portions of each block constituting the equipment 600 used in the flow control system 500. In other words, the bolt fastening structure 100 can be applied to at least one of the flow control device 1 and the equipment 600.
[0088] The bolt fastening structure 100 described in this embodiment can, of course, also be applied to a flow control device equipped with a normally open type flow control valve.
[0089] The bolt fastening structure 100 described in this embodiment can, of course, also be applied to a pressure control device that controls the pressure of a fluid.
[0090] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and it can be expanded or modified without departing from the spirit of the invention. [Industrial applicability]
[0091] This invention can be used, for example, in flow control devices such as mass flow controllers. [Explanation of Symbols]
[0092] 1. Flow control device 2. Main body (bolt-fastened structure) 3. Flow detection mechanism 4 Flow control valve 5 Drive control unit 21a Inflow channel (passage section) 21b Outflow channel (passage) 21c Intermediate channel (passage section) 21d Bypass section (passage section) 22a Inlet side flow path (main body side passage section) 22b Outlet side flow path (body side passage) 31 Thin tube (passage on the fastened side) 102 Shaft 100 bolt fastening structure 100a Structure (Bolt-fastened structure) 100b Structure (Bolt-fastened structure) 102a Outer surface 102b screw thread 200 Block Body 201 Acceptance Department 202a1 Main body side opening 202b1 Main body side opening 211a Screw groove 211b Inside surface 211b1 side part 211b2 side part 211b3 Tapered section 300 Object to be fastened 301 Through hole 302a Opening on fastened side 500 Flow Control System 600 equipment B1~B4 Bolts CA center axis G gap L1 First block (part to be fastened) L2 Second block (block body) L3 Third block (part to be fastened) L4 Fourth block (part to be fastened) L5 Fifth block (part to be fastened) L6 Sixth block (part to be fastened) S sealant
Claims
1. A bolted fastening structure used in a flow control device or flow control system, It comprises a bolt, a block body, and a fastened object that is fastened to the block body by the bolt, The bolt has a shaft portion with threads on its outer surface, The fastened body has a through hole through which the shaft portion passes, The aforementioned block body is A receiving portion that receives the shaft portion inserted through the through hole, The opening on the main body side, It has a main body side passage portion which is a fluid passage connected to the main body side opening, The opening on the main body side is located on the same plane as the receiving portion when viewed from the side of the fastened object, The receiving section is, The screw groove is spiral in the non-inserted state of the shaft, and when the shaft is inserted and rotated, it contacts and engages with the screw threads of the shaft. In the non-inserted state of the shaft portion, it has an inner surface located upstream of at least a portion of the helical screw groove in the insertion direction of the shaft portion, The inner surface is a bolt fastening structure located away from the shaft portion inserted into the receiving portion, with a gap in between.
2. The bolt fastening structure according to claim 1, wherein the inner surface is located upstream of the entire screw groove in the insertion direction of the shaft.
3. The bolt fastening structure according to claim 2, wherein the inner surface is located along the entire circumference in the circumferential direction of the shaft portion inserted into the receiving portion.
4. The inner surface has a plurality of side surfaces that are at different distances from the central axis of the shaft portion. The bolt fastening structure according to any one of claims 1 to 3, wherein the plurality of side portions are arranged in order from the upstream side to the downstream side in the insertion direction of the shaft portion, in order of decreasing distance from the central axis of the shaft portion, or in order of increasing distance.
5. The bolt fastening structure according to any one of claims 1 to 4, wherein the inner surface has a tapered portion that approaches the central axis of the shaft or moves away from the central axis as it moves from the upstream side to the downstream side in the insertion direction of the shaft.
6. The fastened body is The opening on the fastening side, It has a fastened-side passage portion which is a fluid passage connected to the fastened-side opening, The bolt fastening structure according to any one of claims 1 to 5, wherein the main body side passage portion is connected to the fastened side passage portion via the main body side opening and the fastened side opening.
7. The bolt fastening structure according to any one of claims 1 to 6, further comprising a sealing material located around the opening on the main body side.
8. The bolt fastening structure according to claim 7, wherein the inner surface is positioned across the space between the screw groove and the sealing material when viewed from the side of the fastened object.
9. The bolt fastening structure according to any one of claims 1 to 8, wherein the distance between the central axis of the shaft portion and the inner surface is greater than the maximum radius of the helical screw groove.
10. The bolt fastening structure according to any one of claims 1 to 9, wherein the distance between the central axis of the shaft portion and the inner surface is greater than the radius of the through hole in the fastened body.
11. A bolt fastening structure according to any one of claims 1 to 10, A flow detection mechanism for detecting the flow rate of the fluid flowing inside the bolt fastening structure, Flow control valve and A flow control device comprising: a drive control unit that drives the flow control valve based on the detection result of the flow detection mechanism.
12. A passing step of inserting and passing the shaft portion of a bolt having threads on its outer surface into a through hole of a fastened object, A bolt fastening method comprising: a fastening step of inserting the shaft portion that has passed through the through hole into a receiving portion of a block body which has an inner surface located at a distance from the inserted shaft portion via a gap, and a helical screw groove when the shaft portion is not inserted, and fastening the object to be fastened and the block body by engaging the screw threads of the bolt with the screw groove of the receiving portion.