Fluid control valve and fluid control device

Abstract

The present invention comprises: a flow passage block 2 in which an internal flow passage 2R is formed so as to suppress flow rate fluctuation by balancing the pressure applied to a valve body; an orifice 5 accommodated in the flow passage block 2, the orifice 5 having a valve seat surface 5a and an inflow passage 51 that opens in the valve seat surface; a valve body 6 having a seating surface 6a seated on the valve seat surface 5a; and an actuator part 7 for driving the valve body 6. A fluid introduction passage 62 for introducing fluid from the seating surface 6a to a reverse-surface 6b side is formed in the valve body 6. The fluid introduction passage 62 is allowed to communicate with the inflow passage 51.

Description

Fluid control valve and fluid control device

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

[0002] Conventionally, as shown in Patent Document 1, a fluid control valve has been considered to include a flow path block in which an internal flow path is formed, an orifice housed in the flow path block and having a valve seat surface, a valve body having a seat surface that seats on the valve seat surface, and an actuator unit that drives the valve body.

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

[0004] However, when the above-mentioned fluid control valve is used to control a fluid in a large flow rate range (for example, 75 SLM), the differential pressure between the primary side pressure and the secondary side pressure becomes large, which can cause unstable control of the valve element. For example, when the valve element is moved in the opening direction from a state in which its seating surface is seated on the valve seat surface (when the valve is closed), the valve element is subjected to not only the driving force from the actuator unit but also the primary side pressure, which causes the valve element to move forcefully, making it more likely to cause fluctuations in the flow rate.

[0005] Therefore, the present invention has been made to solve the above-mentioned problems, and its main objective is to suppress fluctuations in flow rate by balancing the pressure around the valve body.

[0006] 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 that is provided in communication with the internal flow path and has a valve seat surface and an inlet path that opens to the valve seat surface, a valve body that has a seating surface that seats on the valve seat surface, and an actuator unit that drives the valve body, wherein the valve body is formed with a fluid inlet path that introduces fluid from the seating surface to the back side opposite the seating surface, and the fluid inlet path is in communication with the inlet path.

[0007] With such a fluid control valve, the pressure of the fluid in the inlet passage (pressure on the primary side (supply side)) is transmitted to the back side through a fluid inlet passage that introduces fluid from the seating surface of the valve body to the back side opposite the seating surface. This means that the pressure applied to the back side is substantially the same as the pressure applied to the seating surface, making it possible to balance the pressures applied to the valve body and suppress fluctuations in the flow rate.

[0008] It is desirable that the fluid introduction passage communicate with the inlet passage when the seating surface is seated on the valve seat. With this configuration, even when the fluid control valve is closed, the pressure applied to the back surface is substantially the same as the pressure applied to the seating surface, and the pressure applied to the valve element can be balanced before the valve opening operation, stabilizing control when the valve is opened and suppressing fluctuations in flow rate. Furthermore, since the pressure applied to the valve element can be balanced in the fully closed state, seat leak performance can be improved.

[0009] The fluid control valve of the present invention preferably further includes a valve element accommodating portion that accommodates the valve element, and an annular seal member provided between the outer circumferential surface of the valve element and the inner circumferential surface of the valve element accommodating portion that faces the outer circumferential surface of the valve element. With this configuration, gas that has flowed into the back side of the valve element through the through hole of the valve element can be prevented from flowing toward the outlet path through the outer circumferential surface of the valve element and the inner circumferential surface of the valve element accommodating portion. Furthermore, by providing a seal member on the outer circumferential surface of the valve element, the position of the valve element can be maintained while allowing the valve element to move back and forth, and axial misalignment of the valve element during actuation can be prevented.

[0010] It is desirable that the valve element has a shape of a rotor, and that the fluid introduction passage is formed in the center thereof. With this configuration, it is possible to balance the pressure applied to the valve element having a shape of a rotor, and to suppress fluctuations in the flow rate.

[0011] It is desirable that a groove communicating with the fluid introduction passage is formed on the rear surface of the valve body. With this configuration, fluid can easily flow into the rear surface side of the valve body, making it easier to balance the pressure applied to the valve body.

[0012] The fluid control valve of the present invention further includes a support member made of an elastic material that supports the valve disc, the support member supporting the seating surface-side end face of the valve disc, and the seal member preferably being provided on the outer circumferential surface of the valve disc closer to the back surface than the axial center. With this configuration, the valve disc is supported at two points by the support member and the seal member, preventing axial misalignment of the valve disc during actuation. In particular, because the support member supports the seating surface-side end face of the valve disc and the seal member is provided on the outer circumferential surface of the valve disc closer to the back surface than the axial center, the distance between the two support points can be increased, further preventing axial misalignment of the valve disc during actuation.

[0013] It is desirable that the outer peripheral surface of the valve body be provided with a mounting groove into which the seal member is mounted. This configuration makes it easier to install the seal member and prevents fluctuations in the relative position of the seal member with respect to the valve body. As a result, it is easier to balance the pressure applied to the valve body and suppress fluctuations in the flow rate.

[0014] A specific embodiment of the actuator unit is that the actuator unit drives the valve body by magnetic force and has a core arranged opposite the back surface of the valve body and a solenoid coil wound around the core.

[0015] 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.

[0016] According to the present invention configured in this manner, fluctuations in the flow rate can be suppressed by balancing the pressure around the valve body.

[0017] 1 is a schematic diagram showing a fluid control device according to one embodiment of the present invention; FIG. 1 is a cross-sectional view of a fluid control valve according to the same embodiment; FIG. 2 is a plan view of a mounting block according to the same embodiment; FIG. 3 is a partially enlarged cross-sectional view of the fluid control valve according to the same embodiment; FIG. 4 is a perspective view of a valve body of the fluid control valve according to the same embodiment, (a) a plan view from the back side, and (c) a cross-sectional view along line A-A; FIG. 5 is a schematic diagram showing the pressure applied to the valve body in a fully closed state and the pressure applied to the valve body in an open state in the fluid control valve according to the same embodiment; FIG. 6 is experimental data showing the flow rate of a valve body without a fluid introduction path and the flow rate of a valve body with a fluid introduction path in the fluid control valve; FIG. 7 is a cross-sectional view of a fluid control valve according to a modified embodiment; FIG. 8 is a cross-sectional view of a fluid control valve (normally open type) according to a modified embodiment;

[0018] 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.

[0019] <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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] <Detailed Configuration of Fluid Control Valve 32> As shown in Fig. 2, the fluid control valve 32 of this embodiment includes an orifice 5 having a planar valve seat surface 5a, a valve element 6 having a planar seat surface 6a that seats in surface contact with the valve seat surface 5a, 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.

[0027] 2, the orifice 5 is a valve seat member having a generally solid-of-rotation shape, and is provided in communication with the internal flow path 2R and 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.

[0028] The orifice 5 also has an inflow passage 51 formed therein that allows fluid to flow from the upstream flow passage 2R1 between the valve seat surface 5a and the seating surface 6a. In this embodiment, the inflow passage 51 is a through-hole that penetrates the center of the inside of the valve seat surface 5a from the valve seat surface 5a side to the side opposite the valve seat surface 5a. The inflow passage 51 communicates with the upstream flow passage 2R1 that opens into the bottom surface of the installation recess 2M. A seal member S1, such as an O-ring, is provided between the periphery of the inflow passage 51 and the bottom surface of the installation recess 2M to provide a liquid-tight seal.

[0029] Furthermore, the orifice 5 is formed with an outflow 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 outflow 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 outflow passage 52 communicates with the downstream flow passage 2R2 that opens to the bottom surface of the installation recess 2M.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] As shown in FIG. 2, the actuator unit 7 has a core 71 provided opposite the back surface 6b of the valve body 6 opposite 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.

[0035] The core 71 has a generally cylindrical shape, one end (the upper end in FIG. 2 ) of which is connected to the casing 73, and the other end (the lower end in FIG. 2 ) of which faces the back surface 6 b of the valve body 6 on the side opposite to the seating surface 6 a. The core is made of a magnetic material such as carbon steel for mechanical structures, e.g., S45C.

[0036] 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.

[0037] The casing 73 has a cylindrical shape, and its upper wall is connected to the upper end of the core 71. An elastic body 74 such as a wave spring is provided between the upper wall of the casing 73 and the solenoid coil 72 (specifically, the upper end 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.

[0038] 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 back surface 6b of the valve body 6, opposite the seating surface 6a.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] Specifically, as shown in Figures 2 and 3, the mounting block 8 is formed with a counterbore 81 that accommodates the head 10a of the bolt 10. In this embodiment, the counterbore 81 accommodates the entire head 10a of the bolt 10. In other words, the depth of the counterbore 81 is the same as or greater than the height of the head 10a of the bolt 10. Here, the mounting block 8 has a valve element accommodating portion 82 that accommodates the valve element 6, and multiple counterbore portions 81 are provided to surround the valve element accommodating portion 82. The upper opening of the valve element accommodating portion 82 is closed by the diaphragm seal 12 described above.

[0043] 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.

[0044] 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.

[0045] 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 (see FIG. 2). Here, "the solenoid coil 72 overlaps 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 positioned 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.

[0046] 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.

[0047] 2 and 4 to 6, in the fluid control valve 32 of this embodiment, a fluid inlet passage 62 is formed in the valve body 6 to introduce fluid from the seating surface 6a to the back surface 6b opposite the seating surface 6a. The pressure of the fluid in the inlet passage 51 (primary pressure Pp) is transmitted to the back surface 6b of the valve body through the fluid inlet passage 62. With this configuration, the pressure applied to the back surface 6b is substantially the same as the pressure applied to the seating surface 6a, so that the pressures applied to the valve body 6 can be balanced and fluctuations in the flow rate can be suppressed.

[0048] Specifically, the fluid introduction passage 62 is a through-hole formed in the center of the valve disc 6, which has a generally solid-of-rotation shape (see FIG. 5). When the seating surface 6a is seated on the valve seating surface 5a, the fluid introduction passage 62 communicates with the inlet passage 51, and the pressure of the fluid in the inlet passage 51 is transmitted to the back surface 6b of the valve disc through the fluid introduction passage 62. The opening diameter of the fluid introduction passage 62 at the seating surface 6a is smaller than the opening diameter of the inlet passage 51 at the valve seating surface 5a (see FIG. 4). The fluid introduction passage 62 is formed along the central axis of the valve disc 6 and has a uniform cross-sectional shape.

[0049] Furthermore, a groove 63 communicating with the fluid introduction passage 62 is formed on the back surface 6b of the valve body 6. This groove 63 facilitates the fluid flowing from the fluid introduction passage 62 to the back surface 6b of the valve body 6 to be distributed throughout the entire back surface 6b. Specifically, the groove 63 extends linearly radially outward from the fluid introduction passage 62. In this embodiment, the groove 63 is formed from one end to the other end of the diameter portion so as to communicate with the fluid introduction passage 62, which opens in the center of the back surface 6b of the valve body 6 (see FIG. 5).

[0050] 4, in the fluid control valve 32, an annular seal member 11 such as an O-ring is provided between the outer peripheral surface of the valve element 6 and the inner peripheral surface of the mounting block 8 that faces the outer peripheral surface of the valve element 6. Specifically, the seal member 11 is provided between the outer peripheral surface of the valve element 6 and the inner peripheral surface of the valve element accommodating portion 82 of the mounting block 8. This seal member 11 provides a liquid-tight seal between the seating surface 6a side and the back surface 6b side of the valve element 6.

[0051] This seal member 11 is provided on the outer circumferential surface of the valve disc 6, closer to the back surface 6b than the axial center. As a result, the valve disc 6 is supported at two points by the support member 9 and the seal member 11, preventing axial misalignment of the valve disc 6 when actuated. In particular, because the support member 9 supports the end face of the valve disc 6 on the seating surface 6a side, and the seal member 11 is provided on the outer circumferential surface of the valve disc 6, closer to the back surface 6b than the axial center, the distance between the two support points can be increased, further preventing axial misalignment of the valve disc 6 when actuated.

[0052] 4 to 6, in this embodiment, an attachment groove 64 into which the seal member 11 is attached is provided on the outer peripheral surface of the valve body 6. This attachment groove 64 makes it easy to install the seal member 11 and prevents fluctuations in the relative position of the seal member 11 with respect to the valve body 6. As a result, it is easy to balance the pressure applied to the valve body 6, and fluctuations in the flow rate can be suppressed.

[0053] Next, the operation of the fluid control valve 32 of this embodiment will be briefly described together with the pressure applied to the valve body 6.

[0054] 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.

[0055] In this fully closed state, as shown in Figure 6(a), the inlet passage 51 of the orifice 5 and the fluid introduction passage 62 of the valve body 6 are connected, and fluid is introduced from the inlet passage 51 through the fluid introduction passage 62 to the back surface 6b side of the valve body 6. As a result, the primary pressure Pp is applied to the entire back surface 6b of the valve body 6. In other words, the pressure applied to the back surface 6b is substantially the same as the pressure applied to the seating surface 6a, and the pressures applied to the valve body 6 can be balanced.

[0056] Here, the outer peripheral surface of the valve element 6 and the inner peripheral surface of the mounting block 8 are sealed by a seal member 11, so that the fluid introduced into the back surface 6b does not return from the outer peripheral surface of the valve element 6 to the seating surface 6a side (secondary side). In other words, a closed space connected to the fluid introduction path 62 is formed on the back surface side of the valve element 6. In this embodiment, the closed space is formed by the back surface 6b of the valve element 6, the diaphragm seal 12, the inner peripheral surface of the valve element accommodating portion 82, and the seal member 11.

[0057] 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, casing 73, mounting block 8, and 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 separates from the valve seat surface 5a of the orifice 5, resulting in an open valve state. Here, the pressure applied to the valve element 6 is balanced, making it possible to stabilize control of the valve opening operation. The valve opening of the fluid control valve 32 is adjusted by controlling the current passed through the solenoid coil 72.

[0058] Furthermore, even in this open valve state, as shown in FIG. 6(b), the inlet passage 51 of the orifice 5 and the fluid introduction passage 62 of the valve element 6 are connected, and fluid is introduced from the inlet passage 51 through the fluid introduction passage 62 to the back surface 6b of the valve element 6. As a result, even in the open valve state, the primary pressure Pp is applied to the entire back surface 6b of the valve element 6. In other words, the pressure applied to the back surface 6b is substantially the same as the pressure applied to the seating surface 6a, and the pressures applied to the valve element 6 can be balanced. Note that the symbol Ps in FIG. 6(b) indicates the secondary pressure.

[0059] <Effects of this embodiment> According to the fluid control device 100 of this embodiment configured as described above, the pressure of the fluid in the inlet passage 51 (primary side (supply side) pressure Pp) is transmitted to the back surface 6b through the fluid introduction passage 62 that penetrates from the seating surface 6a of the valve body 6 to the back surface 6b on the opposite side of the seating surface 6a. Therefore, the pressure applied to the back surface 6b is substantially the same as the pressure applied to the seating surface 6a, making it possible to balance the pressures applied to the valve body 6 and suppress fluctuations in the flow rate.

[0060] 7 shows experimental data showing (a) the flow rate of the valve disc 6 without the fluid inlet path 62 and (b) the flow rate of the valve disc 6 with the fluid inlet path 62 in the fluid control valve 32. As can be seen from FIG. 7(a), when the valve disc 6 does not have the fluid inlet path 62, the valve disc moves forcefully when it is moved in the valve opening direction from the valve closed state, causing the fluid to rush in (the flow rate changes suddenly). On the other hand, as can be seen from FIG. 7(b), when the valve disc 6 has the fluid inlet path 62, the movement of the valve disc 6 is gentler when it is moved in the valve opening direction from the valve closed state, preventing the fluid from rushing in and enabling stable control of the flow rate.

[0061] In this embodiment, when the seating surface 6a is seated on the valve seat surface 5a (fully closed state), the fluid introduction path 62 of the valve element 6 communicates with the inlet path 51 of the orifice 5, so even in the fully closed state, the pressure applied to the back surface 6b of the valve element 6 is substantially the same as the pressure applied to the seating surface 6a (primary side pressure pp), making it possible to balance the pressure applied to the valve element 6 before the valve opening operation, stabilizing control when the valve is opened and suppressing fluctuations in the flow rate. Furthermore, because the pressure applied to the valve element 6 can be balanced in the fully closed state, seat leak performance can be improved.

[0062] <Other Embodiments> For example, the fluid control valve 32 in the above embodiment has a configuration in which the inlet channel 51 opens at the center of the orifice 5 and the outlet channel 52 opens radially outward (center-in configuration), but as shown in Fig. 8 , the fluid control valve 32 may have a configuration in which the outlet channel 52 opens at the center of the orifice 5 and the inlet channel 51 opens radially outward (center-out configuration). In this configuration, a fluid introduction channel 62 is formed in the valve body 6 so as to open into the inlet channel 51. In Fig. 8 , a plurality of fluid introduction channels 62 are formed, and each fluid introduction channel 62 is inclined with respect to the central axis of the valve body 6 and is formed so as to approach the central axis as it goes toward the back surface 6b.

[0063] 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.

[0064] 9, in the normally open type, a permanent magnet 13 is built into the valve element 6, and when no current is flowing through the solenoid coil 72 of the actuator unit 7, the magnetic force of the permanent magnet 13 attracts the valve element 6 toward the core, bringing it into 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 13 of the valve element 6 repels from the core 71, and the seating surface 6a of the valve element 6 presses against the valve seat surface 5a of the orifice 5, bringing it into a fully closed state.

[0065] In this configuration, when the fluid introduction passage 62 is formed in the valve body 6, as shown in Fig. 9, it is considered that the permanent magnet 13 built into the valve body 6 is annular and arranged around the fluid introduction passage 62. Note that even in the normally open type, a center-out configuration may be used as described above.

[0066] Furthermore, 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.

[0067] In addition, in the above embodiment, the valve body 6 is accommodated in the valve body accommodating portion 82 formed in the mounting block 8, but the flow path block 2 may be configured to have a valve body accommodating portion that accommodates the valve body 6.

[0068] In the above embodiment, the fluid control valve 32 is configured to be provided upstream of the flow rate sensor 31 , but it may also be configured to be provided downstream of the flow rate sensor 31 .

[0069] 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.

[0070] Furthermore, although the fluid introduction passage 62 in the above embodiment was a through hole, the fluid introduction passage 62 may be configured to introduce fluid to the back side of the valve body 6, and may be configured, for example, to connect the seating surface 6a of the valve body 6 with a portion of the outer peripheral surface facing the closed space.

[0071] In the above embodiment, the mounting groove 64 is formed on the outer peripheral surface of the valve body 6, but a mounting groove for accommodating the seal member 11 may be formed on the inner peripheral surface of the valve body accommodating portion 82.

[0072] The fluid control valve in the above embodiment is a solenoid valve that drives the valve element 6 by a solenoid, but the type of actuator is not limited thereto, and it may be, for example, a piezo valve that drives the valve element 6 by a piezo actuator.

[0073] 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.

[0074] 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.

[0075] According to the present invention, fluctuations in the flow rate can be suppressed by balancing the pressure around the valve body.

[0076] DESCRIPTION OF SYMBOLS 100: Fluid control device 2: Flow path block 2R: Internal flow path 31: Fluid sensor 32: Fluid control valve 4: Control unit 5: Orifice 5a: Valve seat surface 51: Inflow path 6: Valve body 6a: Seating surface 6b: Back surface 62: Through hole (liquid introduction path) 63: Groove 64: Mounting groove 7: Actuator unit 8: Mounting block 9: Support member 11: Sealing member

Claims

1. A fluid control valve comprising: 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 and an inlet path opening onto the valve seat surface; a valve body having a seating surface that seats on the valve seat surface; and an actuator unit that drives the valve body, wherein the valve body has a fluid inlet path formed in it for introducing fluid from the seating surface to a back side opposite the seating surface, and the fluid inlet path communicates with the inlet path.

2. The fluid control valve according to claim 1, wherein the fluid introduction passage communicates with the inlet passage when the seating surface is seated on the valve seat surface.

3. A fluid control valve as described in claim 1 or 2, further comprising: a valve body accommodating section that accommodates the valve body; and an annular sealing member provided between the outer peripheral surface of the valve body and the inner peripheral surface of the valve body accommodating section that faces the outer peripheral surface of the valve body.

4. A fluid control valve according to any one of claims 1 to 3, wherein the valve element is in the shape of a rotary body, and the fluid introduction passage is formed in the center thereof.

5. A fluid control valve according to any one of claims 1 to 4, wherein a groove communicating with the fluid introduction passage is formed on the rear surface.

6. A fluid control valve as described in claim 3, further comprising a support member made of an elastic material that supports the valve body, the support member supporting the end face of the valve body on the seating surface side, and the sealing member being provided on the outer peripheral surface of the valve body closer to the back surface than the axial center.

7. A fluid control valve according to claim 3 or 6, wherein a mounting groove for mounting the sealing member is provided on the outer peripheral surface of the valve body.

8. A fluid control valve as claimed in any one of claims 1 to 7, wherein the actuator section drives the valve element by magnetic force and has a core provided opposite the back surface of the valve element, and a solenoid coil arranged around the core.

9. A fluid control device comprising: a fluid control valve according to any one of claims 1 to 8; 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.

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