Fluid control valve and fluid control device

Abstract

The present invention improves magnetic force by increasing the outer diameter of a solenoid coil, and is provided with: a flow path block in which an internal flow path is formed; an orifice that is accommodated in the flow path block and has a valve seat surface; a valve body that has a seat surface to be seated on the valve seat surface; a mounting block that is attached to the flow path block and accommodates the valve body; and an actuator unit that drives the valve body with magnetic force. The actuator unit has a core that is provided so as to face the surface on the opposite side to the seat surface of the valve body, and a solenoid coil that is disposed around the core. The mounting block is attached to the flow path block by means of a bolt. A counterbore unit that accommodates the head portion of the bolt is formed. The solenoid coil is disposed so as to overlap on the upper surface of the head portion.

Description

Fluid control valve and fluid control device

[0001] The present invention relates to a fluid control valve and a fluid control device.

[0002] As disclosed in Patent Document 1, a conventional fluid control valve has been considered, in which an orifice having a valve seat is housed in a flow path block having an internal flow path, and a mounting block housing a valve element having a seat is attached to the flow path block. In this fluid control valve, an actuator unit that drives the valve element by magnetic force is attached to the top surface of the mounting block. Specifically, a casing housing an iron core and a solenoid coil is screwed onto the mounting block.

[0003] Japanese Patent Application Laid-Open No. 2024-28101

[0004] One possible configuration for attaching the mounting block to the flow path block is to fasten the mounting block to the flow path block with bolts. Specifically, as shown in Figure 14, it is possible to fasten the mounting block to the flow path block by providing bolts on the top surface of the mounting block outside the casing.

[0005] On the other hand, in the above-mentioned fluid control valve, it is required to increase the magnetic force acting on the valve body, and to achieve this, it is conceivable to increase the outer diameter of the solenoid coil.

[0006] However, because the bolts are attached to the outside of the casing that houses the solenoid coil, the bolt heads get in the way, limiting the size of the solenoid coil's outer diameter. While it is possible to increase the outer diameter of the solenoid coil by increasing the size of the mounting block, this would result in an increase in the size of the fluid control valve itself. For example, in semiconductor manufacturing applications, where the size of the fluid control valve or a fluid control device using the fluid control valve is specified, the size of the mounting block cannot be increased.

[0007] SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its main object is to increase the outer diameter of the solenoid coil to improve the magnetic force.

[0008] That is, the fluid control valve according to the present invention comprises a flow path block in which an internal flow path is formed, an orifice provided in communication with the internal flow path and having a valve seat surface, a valve body having a seating surface that seats on the valve seat surface, a mounting block attached to the flow path block and accommodating the valve body, and an actuator unit that drives the valve body by magnetic force, wherein the actuator unit has a core provided opposite to the seating surface of the valve body and a solenoid coil arranged around the core, the mounting block is attached to the flow path block by a bolt, a countersunk portion is formed to accommodate the head of the bolt, and the solenoid coil is arranged so as to overlap the upper surface of the head of the bolt.

[0009] In this type of fluid control valve, the mounting block is formed with a counterbore that accommodates the bolt head, and the solenoid coil is positioned so that it overlaps the top surface of the bolt head, so the bolt head does not get in the way and the outer diameter of the solenoid coil can be increased, thereby improving the magnetic force acting on the valve element.

[0010] It is desirable that the counterbore accommodate the entire head of the bolt. With this configuration, the bolt head does not protrude above the top surface of the mounting block, so the outer diameter of the solenoid coil can be increased without the bolt head getting in the way. In addition, the distance between the solenoid coil and the mounting block can be shortened, making it easier for magnetic flux from the solenoid coil to flow to the mounting block and improving the magnetic force acting on the valve body.

[0011] As a specific embodiment of the mounting block and the countersunk portion, it is desirable that the mounting block has a valve body accommodating portion that accommodates the valve body, and that multiple countersunk portions are provided so as to surround the valve body accommodating portion.

[0012] It is desirable that the mounting block be rectangular in plan view, with the valve element accommodating portion formed in its center, and that the counterbore be provided at each of the four corners of the mounting block in plan view. With this configuration, it is possible to easily provide multiple counterbore portions in a configuration in which a valve element accommodating portion that is circular in plan view is formed on a mounting block that is rectangular in plan view.

[0013] The solenoid coil is preferably wound around a bobbin through which the core is inserted, and the flange of the bobbin is preferably in contact with the top surface of the bolt head. With this configuration, the flange of the bobbin is in contact with the top surface of the bolt head, which makes it easier for magnetic flux to flow to the bolt and improves the magnetic force acting on the valve body.

[0014] It is desirable that the actuator unit has a casing made of a magnetic material that houses the core and the solenoid coil, and that the casing covers the top surface of the bolt head together with the solenoid coil. With this configuration, magnetic flux generated by the solenoid coil can be efficiently passed through the bolt and mounting block, improving magnetic efficiency.

[0015] The casing is preferably fixed to the side surface of the mounting block, which eliminates the need for a structure for fixing the casing to the top surface of the mounting block, and allows the outer diameter of the solenoid coil to be increased.

[0016] The mounting block preferably has a rectangular parallelepiped shape, and the casing preferably has cover walls that cover opposing side surfaces of the mounting block, and the cover walls are fixed to the mounting block. For example, if the flow path block has a rectangular parallelepiped shape with a longitudinal direction, one side surface of the mounting block is attached to the flow path block along the longitudinal direction. If the cover walls are fixed to opposing side surfaces of the mounting block in the longitudinal direction, the width of the mounting block can be increased. As a result, the outer diameter of the solenoid coil can be increased. On the other hand, if the cover walls are fixed to opposing side surfaces of the mounting block in the width direction, the distance to other devices (e.g., flow rate sensors and other valves) mounted along the longitudinal direction of the flow path block can be shortened.

[0017] The fluid control valve of the present invention further includes a distance adjustment mechanism for adjusting the distance between the valve element and the core. The distance adjustment mechanism preferably includes a female thread formed on the wall of the casing opposite the valve element and a male thread formed on the end of the core opposite the valve element and threadedly engaged with the female thread. In this configuration, by rotating the core relative to the casing, the male thread moves to threadably engage with the female thread, thereby adjusting the distance between the valve element and the core. With this configuration, adjusting the distance between the core and the valve element allows for adjustment (increase or decrease) of the optimal magnetic field (magnetic flux density). This allows for adjustment of, for example, the gas resolution (the gradient from 0 to maximum flow rate output) and the opening start point (the point at which gas begins to flow). Furthermore, for example, by adjusting the position of the core while applying a constant voltage, the flow rate value and the gradient of the flow characteristics at the start of opening can be adjusted. Furthermore, for example, the valve opening degree at full open can be adjusted. For example, by applying a constant voltage while flowing a fluid, the valve opening degree can be set to the desired full scale (FS) flow rate. Furthermore, for example, when it is desired to control a minute flow rate, the magnetic force attracting the valve body is weakened by increasing the distance between the core and the valve body, thereby enabling control of the minute flow rate.

[0018] The core preferably has a core body around which the solenoid coil is disposed, and a large-diameter portion formed at the end of the core body opposite the valve body and having a diameter larger than that of the core body, with the male thread portion formed on the outer peripheral surface of the large-diameter portion. By forming the male thread portion on the large-diameter portion, which has a diameter larger than that of the core body, the larger the outer diameter of the male thread portion, the smaller the travel distance (lead) can be, assuming the same thread pitch and core rotation amount (rotation angle). As a result, the travel resolution per rotation angle can be improved, enabling fine adjustment of the distance between the core and the valve body.

[0019] In order to prevent the male threaded portion from loosening relative to the female threaded portion and changing the distance between the core and the valve body after adjusting the distance between the core and the valve body, it is desirable that the male threaded portion has an extension portion that extends outward from the upper wall portion of the casing while threaded into the female threaded portion, and that the distance adjustment mechanism further has a nut member that screws into the extension portion and adheres tightly to the wall portion of the casing, thereby preventing the male threaded portion from loosening.

[0020] The core is fixed to the casing, and the fluid control valve of the present invention preferably further includes a spacer provided on the upper or lower surface of the head of the bolt to adjust the distance between the valve element and the core. With this configuration, the magnetic field (magnetic flux density) can be adjusted (increased or decreased) to an optimal value by adjusting the distance between the core and the valve element. This allows, for example, adjustment of the valve opening when fully open. For example, by applying a constant voltage while flowing a fluid, the valve opening can be set to achieve the desired full-scale (FS) flow rate. Furthermore, when controlling a minute flow rate, for example, increasing the distance between the core and the valve element weakens the magnetic force attracting the valve element, making it possible to control the minute flow rate.

[0021] In addition, the fluid control device according to the present invention is characterized by comprising the above-mentioned fluid control valve, a fluid sensor that measures the flow rate or pressure of the fluid, and a control unit that controls the opening degree of the fluid control valve based on the measurement value measured by the fluid sensor and a predetermined target value.

[0022] Furthermore, a fluid control device according to the present invention includes the above-described fluid control valve, a fluid sensor provided in the flow path block for measuring the flow rate or pressure of the fluid, a control unit for controlling the opening of the fluid control valve based on the measurement value measured by the fluid sensor and a predetermined target value, and an external housing that houses the mounting block, the actuator unit, and the fluid sensor, and the side of the mounting block that is not covered by the casing is in contact with the external housing. With this configuration, heat from the mounting block can be dissipated to the external housing.

[0023] The external housing is preferably fixed to the mounting block. With this configuration, heat from the mounting block can be dissipated to the external housing. Also, if a casing is sandwiched between the mounting block and the external housing, heat from the casing can be dissipated to the external housing, improving heat dissipation efficiency.

[0024] According to the present invention configured in this manner, the outer diameter of the solenoid coil can be increased to improve the magnetic force.

[0025] 1 is a schematic diagram showing a fluid control device according to an embodiment of the present invention; FIG. 2 is a cross-sectional view of a fluid control valve according to the embodiment; FIG. 3 is a plan view of a mounting block according to the embodiment; FIG. 4 is an exploded perspective view showing the mounting block and actuator unit removed from the flow path block according to the embodiment; FIG. 5 is a perspective view showing the fluid control valve according to the embodiment; FIG. 6 is a cross-sectional view showing the relationship between the external housing and the mounting block according to the embodiment; FIG. 7 is a diagram showing analysis results of magnetic fields of (a) a conventional fluid control valve, (b) a fluid control valve according to the present embodiment, and (c) a fluid control valve according to a comparative example; FIG. 8 is a cross-sectional view of a fluid control valve according to a modified embodiment; FIG. 9 is a partial cross-sectional perspective view showing a distance adjustment mechanism according to the modified embodiment; FIG. 10 is a schematic diagram showing before and after distance adjustment by the distance adjustment mechanism according to the modified embodiment; FIG. 11 is a graph showing flow rate characteristics when the distance between the valve body and the core is changed; FIG. 12 is a cross-sectional view of a fluid control valve according to a modified embodiment; FIG. 13 is a cross-sectional view of a conventional fluid control valve;

[0026] An embodiment of a fluid control device using a fluid control valve according to the present invention will be described below with reference to the drawings. Note that, for ease of understanding, all of the drawings shown below are drawn in a schematic manner with appropriate omissions or exaggerations. Identical components are given the same reference numerals, and their descriptions will be omitted where appropriate.

[0027] <Device Configuration> The fluid control device 100 of this embodiment is used in a semiconductor manufacturing process by being incorporated into, for example, a semiconductor manufacturing device, and is provided, for example, on one or more gas supply lines connected to a semiconductor processing chamber to control the flow rate of process gas flowing through each gas supply line.

[0028] Specifically, the fluid control device 100 is a so-called differential pressure mass flow controller (differential pressure MFC), and as shown in FIG. 1, includes a flow path block 2 in which an internal flow path 2R is formed, and a fluid control device 3 including a flow sensor 31 and a fluid control valve 32 mounted on the flow path block 2.

[0029] The flow path block 2 has a rectangular parallelepiped shape, and a flow rate sensor 31 and a fluid control valve 32 are provided on a predetermined surface of the flow path block 2. A concave accommodating recess 2M for mounting the fluid control valve 32 is formed on a predetermined surface of the flow path block 2, and the accommodating recess 2M divides the internal flow path 2R into an upstream flow path 2R1 and a downstream flow path 2R2. One end of the upstream flow path 2R1 opens on, for example, the bottom surface of the accommodating recess 2M, and one end of the downstream flow path 2R2 opens on, for example, the bottom surface of the accommodating recess 2M. The flow path block 2 is made of a non-magnetic material, such as austenitic stainless steel, e.g., SUS316L.

[0030] The fluid control device 3 controls the fluid in the internal flow path 2R, and includes a flow rate sensor 31 that measures the flow rate of the fluid flowing through the internal flow path 2R, and a fluid control valve 32 that is provided upstream of the flow rate sensor 31. The valve opening of the fluid control valve 32 is feedback-controlled by the control unit 4, which will be described later.

[0031] The flow rate sensor 31 is a differential pressure type flow rate sensor, and has an upstream pressure sensor 31a provided upstream of a fluid resistance element 33, such as a restrictor or orifice, provided in the internal flow path 2R, and a downstream pressure sensor 31b provided downstream of the fluid resistance element 33. The upstream pressure sensor 31a and the downstream pressure sensor 31b are attached in a row together with the fluid control valve 32 on a predetermined surface of the flow path block 2. A flow rate calculation unit 4a of the control unit 4, which will be described later, calculates the flow rate Q flowing through the internal flow path 2R using the upstream pressure P1 of the fluid resistance element 33 detected by the upstream pressure sensor 31a and the downstream pressure P2 of the fluid resistance element 33 detected by the downstream pressure sensor 31b.

[0032] The fluid control valve 32 is provided upstream of the differential pressure flow sensor 31. Specifically, the fluid control valve 32 is a solenoid valve (electromagnetic valve) that controls the flow rate by moving a valve element toward and away from a valve seat using a solenoid. In this embodiment, it is a so-called normally closed type that is fully closed when the valve element is not driven. The fluid control valve 32 is controlled by a valve control section 4b of the control section 4. The detailed configuration of the fluid control valve 32 will be described later.

[0033] The control unit 4 has a flow rate calculation unit 4a that calculates the flow rate Q through the internal flow path 2R based on the upstream pressure P1 and the downstream pressure P2, and a valve control unit 4b that controls the fluid control valve 32 based on the flow rate Q calculated by the flow rate calculation unit 4a and a target flow rate (set value). The control unit 4 is a so-called computer that includes, for example, a CPU, memory, A / D and D / A converters, and input / output means, and performs the functions of the flow rate calculation unit 4a, the valve control unit 4b, etc. by executing a flow rate control program stored in the memory and causing various devices to work together.

[0034] 2, the fluid control valve 32 of this embodiment includes an orifice (i.e., valve seat member) 5 having a planar valve seat surface 5a, a valve element 6 having a planar seat surface 6a that is in surface contact with the valve seat surface 5a and seats on it, and an actuator unit 7 that uses magnetic force to drive the valve element 6. Note that Fig. 2 shows a cross-sectional view taken along a diagonal of a mounting block 8 that has a rectangular shape in a plan view, as will be described later.

[0035] The orifice 5 has a generally solid-of-rotation shape, and as shown in Fig. 2, is provided in communication with the internal flow path 2R and is housed in the installation recess 2M of the flow path block 2. The orifice 5 has an annular valve seat surface 5a formed on its upper surface facing the opening side of the installation recess 2M. The orifice 5 is made of a non-magnetic material, such as austenitic stainless steel, for example, SUS316L.

[0036] Furthermore, a through-hole 51 is formed in the center of the inner side of the valve seat surface 5a, penetrating from the valve seat surface 5a side to the opposite side of the valve seat surface 5a. This through-hole 51 communicates with an upstream flow path 2R1 that opens into the bottom surface of the accommodation recess 2M. A seal member S1 such as an O-ring is provided between the periphery of the through-hole 51 and the bottom surface of the accommodation recess 2M, providing a liquid-tight seal.

[0037] Furthermore, the orifice 5 is formed with a discharge passage 52 that allows the fluid that has flowed into the interior from the valve seat surface 5a to flow out to the downstream flow passage 2R2. In this embodiment, the discharge passage 52 is a through-hole that penetrates from the valve seat surface 5a side to the opposite side of the valve seat surface 5a on the outside of the valve seat surface 5a. This discharge passage 52 communicates with the downstream flow passage 2R2 that opens to the bottom surface of the installation recess 2M.

[0038] The valve element 6 has a generally rotary body shape and is disposed opposite the orifice 5 housed in the housing recess 2M as shown in Fig. 2. The valve element 6 also has a protrusion 61 with a flat seating surface 6a on its top surface. The valve element 6 is made of a magnetic material, such as electromagnetic stainless steel, e.g., KM45.

[0039] The valve element 6 is housed in a mounting block 8 that is attached to a predetermined surface (top surface) of the flow path block 2. The mounting block 8 is made of a magnetic material, such as electromagnetic stainless steel, e.g., KM45. The valve element 6 is supported relative to the mounting block 8 by a support member 9 made of an elastic material, such as a leaf spring. The support member 9 supports the valve element 6 with the seating surface 6a facing the valve seat surface 5a. Specifically, the support member 9 is annular, and the protrusion 61 of the valve element 6 is inserted into its central opening to support the valve element 6. The support member 9 is made of a non-magnetic material, such as austenitic stainless steel, e.g., SUS316L. The support member 9 has spring properties and is made of a corrosion-resistant material suitable for semiconductor gas-contacting parts, taking magnetic permeability into consideration.

[0040] A circular seating surface 6a corresponding to the annular valve seating surface 5a is formed on the valve body 6. When no driving force is applied by the actuator unit 7 to the valve body 6, that is, when the fluid control valve 32 is assembled, the support member 9 is elastically deformed, and the seating surface 6a is urged by the support member 9 against the valve seating surface 5a by the elastic force thereof, so that the seating surface 6a is seated on the valve seating surface 5a.

[0041] The mounting block 8 also fixes the orifice 5 housed in the accommodation recess 2M by being attached to the flow path block 2. Specifically, the surface (lower surface) of the mounting block 8 facing the flow path block 2 comes into contact with the upper surface of the orifice 5, and the lower surface of the orifice 5 is pressed and fixed against the bottom surface of the accommodation recess 2M via a seal member S1. A seal member S2 such as a metal seal is provided between the mounting block 8 and the flow path block 2, providing a liquid-tight seal.

[0042] As shown in FIG. 2, the actuator unit 7 has a core 71 provided opposite to the surface 6b of the valve body 6 opposite to the seating surface 6a, a solenoid coil 72 wound around the core 71, and a casing 73 that houses the core 71 and the solenoid coil 72.

[0043] The core 71 has a generally cylindrical shape, and one end (upper end in FIG. 2 ) located opposite the valve disc 6 is connected to the casing 73, and the other end (lower end in FIG. 2 ) faces a surface 6 b opposite the seating surface 6 a of the valve disc 6. The core is made of a magnetic material such as carbon steel for mechanical structures, e.g., S45C.

[0044] The solenoid coil 72 is wound around the outer circumferential surface of the core 71, and more specifically, is wound around a bobbin 721 through which the core 71 is inserted. The bobbin 721 is provided so as to be slidable relative to the core 71. The bobbin 721 is made of, for example, resin.

[0045] The casing 73 has a cylindrical shape, and a wall portion (top wall portion in FIG. 2 ) located on the opposite side from the valve body 6 is connected to the top end of the core 71. An elastic body 74 such as a wave spring is provided between the top wall portion of the casing 73 and the solenoid coil 72 (specifically, the top end portion of the bobbin 721). The casing 73 is made of a magnetic material, such as carbon steel for mechanical structures, e.g., S45C. The casing 73 and the core 71 may be integrally formed.

[0046] In addition, the casing 73 is attached to the mounting block 8, and by attaching the casing 73 to the mounting block 8, the core 71 connected to the casing 73 is arranged opposite the surface 6b opposite the seating surface 6a of the valve body 6.

[0047] In this embodiment, the solenoid coil 72 is slidably mounted relative to the core 71 and the casing 73. The solenoid coil 72 is pressed toward the mounting block 8 by a wave spring 74 disposed between the upper wall of the casing 73 and the solenoid coil 72 (the upper end of the bobbin 721). The wave spring 74 accommodates dimensional tolerances to secure the solenoid coil 72. The upper end of the core 71 is provided with a flange 71a that protrudes radially outward to prevent the wave spring 74 from rattling in the axial direction. The flange 71a may be formed over the entire circumferential direction or may be formed intermittently in the circumferential direction. If the dimensional precision of each component is sufficient, the wave spring 74 may not be provided.

[0048] A diaphragm seal 12 is provided between the lower end surface of the bobbin 721 and the upper end surface of the mounting block 8, providing a liquid-tight seal between the lower end surface of the bobbin 721 and the upper end surface of the mounting block 8. The diaphragm seal 12 is made of a non-magnetic material, such as austenitic stainless steel, for example, SUS316L.

[0049] <Characteristic Configuration of Fluid Control Valve 32> In the fluid control valve 32 of this embodiment, the mounting block 8 is attached to the flow path block 2 by bolts 10 made of a magnetic material. The bolts 10 are made of a magnetic material, such as chrome molybdenum steel, for example, SCM435. The material of the bolts 10 and the material of the mounting block 8 may be the same or different.

[0050] Specifically, as shown in Figures 2, 3, and 4, the mounting block 8 is formed with a countersunk portion 81 that accommodates the head 10a of the bolt 10. In this embodiment, the countersunk portion 81 is a recess formed downward from the upper surface of the mounting block 8, and accommodates the entire head 10a of the bolt 10. In other words, the depth of the countersunk portion 81 is the same as or greater than the height of the head 10a of the bolt 10. The countersunk portion 81 is formed above the through-hole of the mounting block 8 through which the threaded portion of the bolt 10 is inserted, and has a diameter larger than the diameter of the through-hole. Here, the mounting block 8 has a valve element accommodating portion 82 that accommodates the valve element 6, and a plurality of countersunk portions 81 are provided to surround the valve element accommodating portion 82.

[0051] The mounting block 8 of this embodiment has a rectangular shape in a plan view, with a valve element accommodating portion 82 formed in its center. Because the valve element 6 has a generally solid-of-rotation shape as described above, the valve element accommodating portion 82 has a circular shape in a plan view. Counterbore portions 81 are provided at each of the four corners of the mounting block 8 in a plan view. These counterbore portions 81 open to the top surface of the mounting block 8 and also to the side surfaces of the mounting block 8.

[0052] Here, the inner surface of the countersunk portion 81 is formed along the outer circumferential surface of the head 10a of the bolt 10, and the head 10a of the bolt 10 guides the countersunk portion 81 when the bolt 10 is fastened to the flow path block 2. This makes it possible to suppress axial wobble of the mounting block 8 relative to the flow path block 2. As a result, the central axis of the valve disc 6 housed in the mounting block 8 and the central axis of the orifice 5 tend to align, preventing uneven contact of the valve disc 6 and making it easier for the valve seat surface 5a of the orifice 5 and the seating surface 6a of the valve disc 6 to come into flat contact, thereby improving seat leak performance.

[0053] The solenoid coil 72 is arranged on the mounting block 8 fixed as described above so as to overlap the top surface of the head 10a of the bolt 10. Here, "the solenoid coil 72 overlapping the top surface of the head 10a of the bolt 10" means that the solenoid coil 72 and the top surface of the head 10a overlap in a plan view taken along the central axis of the solenoid coil (when viewed from the drive direction of the fluid control valve 32). In other words, the solenoid coil 72 is arranged so as to be located above the top surface of the head 10a of the bolt 10 and cover the top surface of the head 10a. Specifically, the solenoid coil 72 is arranged so that its central axis coincides with the center of the mounting block 8 (the valve body accommodating portion 82), and the outer periphery of the solenoid coil 72 overlaps the top surface of the head 10a of each of the multiple bolts 10.

[0054] In this embodiment, the solenoid coil 72 is wound around a bobbin 721, and the flange portion 721a of the bobbin 721 is disposed so as to overlap the upper surface of the head 10a of each of the plurality of bolts 10. In this embodiment, the upper surface of the mounting block 8 and the upper surface of the head 10a of the bolt 10 are configured to be flush with each other, and the flange portion 721a of the bobbin 721 is in contact with the upper surface of the head 10a of the bolt 10. Here, the flange portion 721a of the bobbin 721 is in contact with the upper surface of the head 10a of each bolt 10, inside the hexagonal hole.

[0055] Furthermore, the casing 73 covers the top surface of the head 10a of the bolt 10 together with the solenoid coil 72. Specifically, as shown in Figures 2, 5 and 6, the casing 73 has a cylindrical housing main body 731 that houses the solenoid coil 72 and the core 71, and a cover wall portion 732 that is provided at the bottom end of the housing main body 731 and covers the top surface of the mounting block 8 and the top surface of the head 10a of the bolt 10 as well as the side surface of the mounting block 8.

[0056] The casing 73 is fixed to the side surface of the mounting block 8. In this embodiment, the casing 73 has cover wall portions 732 that cover the opposing side surfaces of the mounting block 8, and the cover wall portions 732 are fixed to the mounting block 8.

[0057] In this embodiment, the mounting block 8 is attached to the rectangular parallelepiped flow path block 2 so that one side of the mounting block 8 is aligned along the longitudinal direction of the flow path block 2. The dimension of the mounting block 8 in the width direction is smaller than the dimension of the flow path block 2 in the short side direction (width direction).

[0058] The casing 73 of this embodiment has a pair of cover walls 732 that cover side surfaces that face each other in the width direction of the mounting block 8. The casing 73 is configured not to cover side surfaces that face each other in the longitudinal direction of the mounting block 8. The pair of cover walls 732 are fixed to the side surfaces in the width direction of the mounting block 8 with screws 11. When the pair of cover walls 732 are fixed to the side surfaces in the width direction of the mounting block 8 in this way, the distance to other equipment (the upstream pressure sensor 31a in this embodiment) that is mounted along the longitudinal direction of the flow path block 2 can be shortened.

[0059] The casing 73 may have a pair of cover walls 732 that cover opposing side surfaces of the mounting block 8 in the longitudinal direction. In this case, the casing 73 is configured not to cover opposing side surfaces of the mounting block 8 in the width direction. The pair of cover walls 732 are then fixed to the longitudinal side surfaces of the mounting block 8 with screws 11. When the pair of cover walls 732 are fixed to the longitudinal side surfaces of the mounting block 8 in this manner, the width dimension of the mounting block 8 can be increased. As a result, the outer diameter of the solenoid coil 72 can be increased.

[0060] Next, the operation of the fluid control valve 32 of this embodiment will be briefly described.

[0061] In the fully closed state where no current is flowing through the solenoid coil 72 of the actuator unit 7, the valve body 6 is biased toward the orifice 5 by the elastic force of the support member 9, and the seating surface 6 a of the valve body 6 is in pressing contact with the valve seat surface 5 a of the orifice 5.

[0062] When a current is passed through the solenoid coil 72, a magnetic flux is generated by the solenoid coil 72, and the magnetic flux flows to the valve element 6 through the core 71, the casing 73, the mounting block 8, and the bolt 10. As a result, the valve element 6 is attracted to the core 71, and the seating surface 6a of the valve element 6 moves away from the valve seat surface 5a of the orifice 5, resulting in an open valve state. The valve opening of the fluid control valve 32 is adjusted by controlling the current passed through the solenoid coil 72.

[0063] 1 and 6, the fluid control device 100 of this embodiment further includes an external housing 200 that is provided on a predetermined surface of the flow path block 2 and that houses the flow sensor 31 and the fluid control valve 32. The external housing 200 may also house the control unit 4.

[0064] Specifically, the external housing 200 has a rectangular box shape and houses the mounting block 8, the actuator unit 7, and the flow rate sensor 31. The external housing 200 is fixed to the flow path block 2 or the mounting block 8.

[0065] 6, the external housing 200 is in contact with the cover wall portions 732 of the casing 73 or the side surfaces of the mounting block 8 that are not covered by the casing 73. In this embodiment, the pair of cover wall portions 732 are fixed to the side surfaces of the mounting block 8 in the width direction, and therefore the external housing 200 is in contact with the pair of cover wall portions 732. When fixing the external housing 200 to the mounting block 8, the cover wall portions 732 and the external housing 200 may be fastened together to the mounting block 8 with screws 11, as shown in FIG. 6. Note that FIG. 6 shows an example in which one side wall 201 of the external housing 200 is in contact with the cover wall portions 732, and the other side wall 202 is fastened together with the cover wall portions 732.

[0066] <Analysis Results of Magnetic Field of Fluid Control Valve> Next, analysis results of the magnetic field of (a) a conventional fluid control valve, (b) the fluid control valve of this embodiment, and (c) a comparative fluid control valve are shown in FIG.

[0067] Here, the conventional fluid control valve has a configuration in which there is no bolt below the solenoid coil, while the fluid control valve of this embodiment has a configuration in which a magnetic bolt is located below the solenoid coil. The comparative fluid control valve has a configuration in which the solenoid coil is located inside the bolt in the bolt arrangement of this embodiment. The conventional example and this embodiment have the same power design, etc., except for the presence or absence and arrangement of the magnetic bolt. Furthermore, because the solenoid coil diameters are different between this embodiment and the comparative example, the same amount of power can be obtained by changing conditions such as the wire diameter and number of turns.

[0068] As can be seen from the analysis results shown in Figure 7, in this embodiment, the bolt is located below the solenoid coil, making it easier for magnetic flux to flow through the bolt (see the enlarged view in Figure 7(b)). As a result, in this embodiment, the magnetic force acting on the valve disc is approximately three times greater (from 9.05 N to 27.1 N) than in the conventional example, and approximately twice as great (from 12.8 N to 27.1 N) than in the comparative example. Furthermore, the comparative example has a further reduced number of wire turns compared to this embodiment, resulting in a lower resistance depending on the wire diameter. Therefore, when the same voltage is applied to the comparative example and this embodiment, the comparative example has a lower resistance than this embodiment, resulting in a larger current flow. In other words, the comparative example generates heat more easily than this embodiment, resulting in a higher solenoid coil temperature. When the solenoid coil becomes hot, the resistance of the solenoid coil increases, and the rate of decrease in magnetic force when the same voltage is applied is greater than in this embodiment. Because the surface area of ​​the solenoid coil in this embodiment is larger than that of the comparative example, a heat dissipation effect is achieved, thereby reducing the amount of heat generated by the solenoid coil.

[0069] <Effects of this embodiment> According to the fluid control device 100 of this embodiment configured as described above, the mounting block 8 is formed with a counterbore 81 that accommodates the head 10a of the bolt 10, and the solenoid coil 72 is disposed so as to overlap the upper surface of the head 10a of the bolt 10. This allows the outer diameter of the solenoid coil 72 to be increased without being obstructed by the head 10a of the bolt 10. As a result, the magnetic force acting on the valve disc 6 can be improved.

[0070] Furthermore, since the solenoid coil 72 is arranged to cover the top surface of the head 10a of the bolt 10, which is made of a magnetic material, magnetic flux can easily flow through the bolt 10 to the valve body 6, improving magnetic efficiency and increasing magnetic force.

[0071] Furthermore, since the solenoid coil 72 is arranged so as to overlap the top surface of the head 10a of the bolt 10, the bolt 10 will not come loose unexpectedly, and if the bobbin 721 around which the solenoid coil 72 is wound comes into contact, the bolt 10 will not become loose. Furthermore, it is easy to notice if the bolt 10 is not tightened properly during assembly.

[0072] <Other Embodiments> For example, in addition to the configuration of the above-described embodiment, as shown in FIGS. 8 and 9 , the fluid control valve 32 may further include a distance adjustment mechanism 13 that adjusts the distance between the valve body 6 and the core 71.

[0073] Specifically, the distance adjustment mechanism 13 has a female thread portion 131 formed in a wall portion (top wall portion) of the casing 73 opposite the valve disc 6, and a male thread portion 132 formed in an end portion (top end portion) of the core 71 opposite the valve disc 6, which threads into the female thread portion 131. In this embodiment, the female thread portion 131 penetrates the top wall portion of the casing 73. Then, by rotating the core 71 relative to the casing 73 through the penetration portion in the top wall portion, the male thread portion 132 moves and threads into the female thread portion 131, thereby adjusting the distance between the core 71 and the valve disc 6 (see FIG. 10 ).

[0074] Here, as shown in Figures 8 and 9, the core 71 has a core body 711 around which the solenoid coil 72 is arranged, and a large diameter portion 712 formed at the end (upper end) of the core body 711 opposite the valve body 6 and having a larger diameter than the core body 711.

[0075] A male thread portion 132 is formed on the outer peripheral surface of the large diameter portion 712. An operating portion 134 for rotating the core 71 with a tool is formed on the upper end surface of the large diameter portion 712.

[0076] An elastic body 74 such as a wave spring is provided between the lower end surface of the large diameter portion 712 and the solenoid coil 72 (specifically, the upper end of the bobbin 721). The elastic body 74 presses the solenoid coil 72 toward the mounting block 8.

[0077] Here, since the large diameter portion 712 receives an elastic force from below by the elastic body 74, there is a risk that the male threaded portion 132 may loosen relative to the female threaded portion 131. For this reason, the male threaded portion 132 has an extension portion 132a that extends outward from the upper wall portion of the casing 73 while being threadedly engaged with the female threaded portion 131. The distance adjustment mechanism 13 further has a nut member 133 that threads onto the extension portion 132a and comes into close contact with the upper wall portion of the casing 73, thereby preventing the male threaded portion 132 from loosening.

[0078] Next, an example of adjusting the distance between the valve element 6 and the core 71 will be briefly described. First, with the nut member 133 removed, the operating portion 134 formed on the large diameter portion 712 of the core 71 is rotated with a tool to move the core 71 to the desired position. Then, the nut member 133 is threaded onto the extension portion 132a of the male thread portion 132, and the nut member 133 is brought into close contact with the upper wall portion of the casing 73. This completes the adjustment of the distance between the valve element 6 and the core 71. Note that the nut member 133 may not be provided.

[0079] Fig. 11 is a graph showing the flow rate characteristics when the distance between the valve disc 6 and the core 71 is changed. The graphs shown in Fig. 11 show the distance between the valve disc 6 and the core 71 increasing from left to right. As can be seen from Fig. 11, by increasing the distance between the valve disc 6 and the core 71, the rate of change of the flow rate with respect to the applied voltage becomes smaller, making it possible to control minute flow rates. Furthermore, by increasing the distance between the valve disc 6 and the core 71, the timing at which the fluid control valve 32 begins to open or close can be adjusted.

[0080] In addition to the configuration of the above embodiment, as shown in FIG. 12, a spacer 14 may be provided on the upper surface or the lower surface of the head 10a of the bolt 10 to adjust the distance between the valve body 6 and the core 71.

[0081] 12 shows an example in which the spacer 14 is provided on the upper surface of the head 10a of the bolt 10. In this case, the spacer 14 has an insertion portion 141 that is inserted into the hexagonal hole in the head 10a of the bolt 10, and a spacer body portion 142 that is placed on the upper surface of the head 10a. With this spacer 14, the spacer 14 can be installed simply by inserting the insertion portion 141 into the hexagonal hole, making assembly of the spacer 14 easy. Note that the spacer 14 may also be, for example, annular and provided on the underside of the head of the bolt 10. In this case, the spacer 14 is sandwiched between the underside of the head 10a of the bolt 10 and the bottom surface of the countersunk portion 81.

[0082] By providing the spacer 14 in this manner, the casing 73 is attached at a higher position, thereby increasing the distance between the core 71 fixed to the casing 73 and the valve element 6. By adjusting the thickness of the spacer 14 to adjust the distance between the core 71 and the valve element 6, it is possible to adjust (increase or decrease) the magnetic field (magnetic flux density) to an optimum value. This makes it possible to adjust, for example, the valve opening when fully open. For example, by applying a constant voltage while flowing a fluid, it is possible to set the opening of the valve 32 to achieve the desired full-scale (FS) flow rate. Furthermore, when controlling a minute flow rate, for example, increasing the distance between the core 71 and the valve element 6 weakens the magnetic force attracting the valve element 6, making it possible to control a minute flow rate.

[0083] Furthermore, in the above embodiment, the countersunk portion 81 is configured to accommodate the entire head 10a of the bolt 10, but it may also be configured to accommodate only a portion of the head 10a. In other words, the depth of the countersunk portion 81 may be smaller than the height of the head 10a of the bolt 10. In this case, a space is formed between the solenoid coil 72 (bobbin 721) and the mounting block 8. A magnetic member may be provided in this space.

[0084] The solenoid coil 72 may also be an air-core coil (also called a bobbinless coil) that does not use the bobbin 721. With this configuration, there is no bobbin 721 that would cause magnetic resistance, so the magnetic flux generated by the solenoid coil 72 can pass through the valve body 6 efficiently.

[0085] 13 , the mounting block 8 of the above embodiment may house not only the valve body 6 but also the orifice 5. In this case, the orifice 5 is provided so as to communicate with the upstream flow path 2R1 and the downstream flow path 2R2 that open on one surface (here, the upper surface) of the flow path block 2. By fixing the mounting block 8 to the flow path block 2 with bolts 10, the orifice 5 is fixed to the flow path block 2 by the mounting block 8.

[0086] Furthermore, the fluid control valve 32 of the above embodiment may be of a normally closed type, or may be of a so-called normally open type that is fully open when the valve element 6 is not driven. In the normally closed type, when current is passed through the solenoid coil 72, a magnetic flux is generated by the solenoid coil 72, and the magnetic flux flows to the valve element 6 through the core 71 and the casing 73. As a result, the valve element 6 is attracted to the core 71, and the seating surface 6a of the valve element 6 separates from the valve seat surface 5a of the orifice 5, resulting in an open valve state. However, it is also possible to change the fluid control valve to a normally open type by adjusting the balance between the support force of the support member 9 that supports the valve element 6 and the magnetic force of the magnetic material of the valve element 6. In the case of the normally open type, the valve element 6 may be made of a magnetic material or a non-magnetic material.

[0087] Furthermore, in the normally open type, a permanent magnet may be built into the valve element 6. In this state, when no current flows through the solenoid coil 72 of the actuator unit 7, the magnetic force of the permanent magnet attracts the valve element 6 toward the core, resulting in a fully open state. When current is passed through the solenoid coil 72, a magnetic flux is generated by the solenoid coil 72, and this magnetic flux flows to the valve element 6 through the core 71 and the casing 73. As a result, the permanent magnet of the valve element 6 repels from the core 71, causing the seating surface 6a of the valve element 6 to press into contact with the valve seat surface 5a of the orifice 5, resulting in a fully closed state.

[0088] In the above embodiment, the fluid control valve 32 is arranged upstream of the flow rate sensor 31 , but it may be arranged downstream of the flow rate sensor 31 .

[0089] In the above embodiment, a pressure type flow sensor is used as the flow sensor 31 of the fluid control device 100, but a thermal type flow sensor may also be used. In this case, it is considered that the thermal type flow sensor is installed upstream of the fluid control valve 32. In addition to the flow sensor, a fluid sensor such as a pressure sensor may also be used.

[0090] Furthermore, the fluid control device 100 is not limited to the pressure type and the thermal type, but may be one in which a position sensor is provided in the fluid control valve 32 to measure the relative position between the valve seat surface 5 a and the seating surface 6 a, and the valve opening degree is feedback-controlled based on the measurement value of the position sensor. Furthermore, the fluid control device of the present invention is not limited to the flow rate control device of the above embodiment, but can also be applied to a pressure control device that controls the pressure of a fluid.

[0091] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention.

[0092] The present invention can increase the outer diameter of the solenoid coil to improve the magnetic force.

[0093] DESCRIPTION OF SYMBOLS 100: Fluid control device 200: External housing 2: Flow path block 2R: Internal flow path 32: Fluid control valve 31: Fluid sensor 4: Valve control section 5: Orifice 5a: Valve seat surface 6: Valve body 6a: Seating surface 7: Actuator section 71: Core 72: Solenoid coil 721: Bobbin 721a: Flange section 73: Casing 732: Cover wall section 8: Mounting block 81: Counterbore section 82: Valve body accommodating section

Claims

1. A fluid control valve comprising: a flow path block having an internal flow path formed therein; an orifice communicating with the internal flow path and having a valve seat surface; a valve element having a seating surface that seats on the valve seat surface; a mounting block attached to the flow path block and accommodating the valve element; and an actuator unit that drives the valve element by magnetic force, wherein the actuator unit has a core provided opposite to the seating surface of the valve element and a solenoid coil arranged around the core, the mounting block being attached to the flow path block by a bolt, the mounting block having a counterbore portion that accommodates the head of the bolt, and the solenoid coil being arranged to overlap the upper surface of the head of the bolt.

2. A fluid control valve as set forth in claim 1, wherein said counterbore accommodates the entire head of said bolt.

3. A fluid control valve as described in claim 1 or 2, wherein the mounting block has a valve body accommodating portion that accommodates the valve body, and the countersunk portion is provided in multiple portions so as to surround the valve body accommodating portion.

4. A fluid control valve as described in claim 3, wherein the mounting block is rectangular in plan view, the valve body accommodating portion is formed in the center thereof, and the counterbore portions are provided at each of the four corners of the mounting block in plan view.

5. A fluid control valve as claimed in any one of claims 1 to 4, wherein the solenoid coil is wound around a bobbin through which the core is inserted, and a flange portion of the bobbin contacts the upper surface of the head of the bolt.

6. A fluid control valve as claimed in any one of claims 1 to 5, wherein the actuator section has a casing made of a magnetic material that houses the core and the solenoid coil, and the casing covers the top surface of the head of the bolt together with the solenoid coil.

7. The fluid control valve of claim 6, wherein the casing is secured to a side of the mounting block.

8. A fluid control valve as described in claim 7, wherein the mounting block is rectangular parallelepiped-shaped, and the casing has cover walls that cover opposing side surfaces of the mounting block, and the cover walls are fixed to the mounting block.

9. A fluid control valve as claimed in any one of claims 6 to 8, further comprising a distance adjustment mechanism for adjusting the distance between the valve body and the core, the distance adjustment mechanism having a female threaded portion formed in a wall portion of the casing opposite the valve body, and a male threaded portion formed in the end of the core opposite the valve body and threadedly engaging with the female threaded portion.

10. A fluid control valve as described in claim 9, wherein the core has a core body around which the solenoid coil is arranged, and a large diameter portion formed at the end of the core body opposite the valve body and having a diameter larger than that of the core body, and the male thread portion is formed on the outer peripheral surface of the large diameter portion.

11. A fluid control valve as described in claim 10, wherein the male threaded portion has an extension portion that extends outward from the upper wall portion of the casing while threadedly engaged with the female threaded portion, and the distance adjustment mechanism further has a nut member that threads onto the extension portion and adheres tightly to the wall portion of the casing to prevent loosening of the male threaded portion.

12. A fluid control valve as claimed in any one of claims 6 to 8, wherein the core is fixed to the casing and further comprises a spacer provided on the upper or lower surface of the head of the bolt to adjust the distance between the valve body and the core.

13. A fluid control device comprising: a fluid control valve according to any one of claims 1 to 12; a fluid sensor that measures the flow rate or pressure of a fluid; and a control unit that controls the opening of the fluid control valve based on the measurement value measured by the fluid sensor and a predetermined target value.

14. A fluid control device comprising: a fluid control valve as defined in claim 8; a fluid sensor provided in the flow path block for measuring the flow rate or pressure of the fluid; a control unit for controlling the opening of the fluid control valve based on a measurement value measured by the fluid sensor and a predetermined target value; and an external casing for accommodating the mounting block, actuator unit and fluid sensor, wherein the external casing is in contact with a cover wall portion of the casing or a side of the mounting block that is not covered by the casing.

15. The fluid control device of claim 14, wherein the outer housing is fixed to the mounting block.

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