Fluid control valve and fluid control device

Abstract

To prolong a service life of a fluid control valve while having an inexpensive configuration.SOLUTION: A fluid control valve comprises a valve body that can be moved toward and away from a valve seat, an actuator that moves the valve body, a diaphragm member that is provided between the valve body and the actuator and has a protrusion part that protrudes toward the valve body, and a sphere that is housed inside the protrusion part. The actuator presses a tip part of the protrusion part via the sphere to move the valve body. The sphere is made of a ceramic material.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] As a conventional fluid control valve, as disclosed in Patent Document 1, there has been considered a valve in which a pressing force from an actuator is transmitted to a valve body by a diaphragm member.

[0003] Specifically, in this fluid control valve, a diaphragm member is provided between the actuator and the valve body, and the diaphragm member has a protruding portion that protrudes toward the valve body. A sphere that receives the pressing force of the actuator is provided inside the protruding portion. The actuator moves the valve body by pressing the protruding portion via the sphere. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6141663 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, conventional diaphragm members and spheres are both made of metal such as stainless steel, and the surface of the sphere is coated with fluorine in order to reduce friction therebetween and extend its life.

[0006] However, when the fluid control valve is operated, fretting wear occurs, causing the fluorine coating to peel off, and the stainless steel, which has a high friction coefficient, comes into repeated contact with the metal. As a result, the diaphragm member breaks, which is a factor that hinders the long life of the fluid control valve. It is also possible to apply a coating with a high hardness to the sphere, but this would make the fluid control valve expensive and would not be practical.

[0007] SUMMARY OF THE PRESENT DISCLOSURE The present invention has been made to solve the above-mentioned problems, and has as its object to provide a fluid control valve having a long life while having an inexpensive structure. [Means for solving the problem]

[0008] That is, the fluid control valve of the present invention comprises a valve body that can be moved toward and away from a valve seat, an actuator that moves the valve body, a diaphragm member that is provided between the valve body and the actuator and has a protrusion that protrudes toward the valve body, and a sphere that is housed inside the protrusion, and the actuator moves the valve body by pressing the tip of the protrusion via the sphere, and the sphere is formed from a ceramic material.

[0009] In such a fluid control valve, the sphere housed in the protruding portion of the diaphragm member is made of a ceramic material, so the life of the fluid control valve can be extended compared to when a sphere made of a metal such as stainless steel is used. In addition, since the friction coefficient of a ceramic material is smaller than that of a metal such as stainless steel, there is no need to apply a coating such as a fluorine coating as in the past, and the fluid control valve can be constructed at low cost.

[0010] As a specific embodiment of the sphere, it is preferable that the sphere is made of alumina.

[0011] In order to prevent breakage of the protruding portion and extend the life of the diaphragm member, the thickness of the protruding portion is desirably 100 to 130 μm.

[0012] As a specific embodiment of the diaphragm member, it is preferable that the diaphragm member has a flange portion that expands outward from the base end of the protrusion portion relative to the protrusion portion, and the thickness of the flange portion is 100 to 130 μm.

[0013] As a specific embodiment of the diaphragm member and the protrusion, it is desirable that the diaphragm member is made of a thin metal plate, and the protrusion is formed by plastically deforming the thin metal plate by drawing.

[0014] In order to make the sphere inexpensive to construct, it is preferred that the sphere be free of a surface coating.

[0015] In addition, a fluid control device according to the present invention is characterized in that it comprises the above-mentioned fluid control valve, a fluid sensor that measures a fluid flowing in a flow path, and a valve control unit that controls the fluid control valve based on the measurement value of the fluid sensor. Effect of the Invention

[0016] Thus, according to the present invention, the fluid control valve can be constructed inexpensively and have a long life. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating a schematic configuration of a fluid control device according to an embodiment of the present invention. [Diagram 2] 2 is a partially enlarged cross-sectional view showing an orifice and a valve body of the fluid control valve of the embodiment. FIG. [Diagram 3] 4 is a cross-sectional view showing details of a diaphragm member of the embodiment. FIG. [Figure 4] 4 shows the results of cycle life tests of a conventional fluid control valve and the fluid control valve of the present embodiment. [Diagram 5] FIG. 13 is a diagram illustrating a configuration of a fluid control device according to a modified embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a fluid control device according to an embodiment of the present invention will be described with reference to the drawings. Note that in all of the drawings shown below, for ease of understanding, some parts are omitted or exaggerated as appropriate and schematic drawings are used. The same components are given the same reference numerals and the description thereof is omitted as appropriate.

[0019] <Device configuration> The fluid control device 100 of this embodiment is a so-called mass flow controller, and is used to control the flow rate of a gas supplied to a chamber in which a semiconductor manufacturing process is performed, for example. Note that the fluid control device 100 may control not only a gas but also a liquid.

[0020] Specifically, as shown in FIG. 1, the fluid control device 100 includes a flow path block 2 having a flow path R formed therein, a fluid control valve 3 for controlling the gas in the flow path R, a fluid sensor 4 for measuring the flow rate of the flow path R, and a control unit 5 for controlling the fluid control valve 3 based on the measurement value measured by the fluid sensor 4.

[0021] The flow path block 2 is formed with an accommodating recess 21 in which the fluid control valve 3 is attached. The accommodating recess 21 is formed on one surface (the upper surface in FIG. 1) of the flow path block 2. An upstream flow path R1 is connected to a bottom surface of the accommodating recess 21, and a downstream flow path R2 is connected to an inner peripheral surface of the accommodating recess 21. In other words, the flow path R formed in the flow path block 2 is divided by the accommodating recess 21 into the upstream flow path R1 and the downstream flow path R2.

[0022] A gas inlet port (not shown) is provided at the upstream end of the upstream flow passage R1, and a gas outlet port (not shown) is provided at the downstream end of the downstream flow passage R2.

[0023] The fluid control valve 3 is a so-called normally closed piezo valve, and the opening degree thereof is controlled by an applied voltage. The fluid control valve 3 may be a so-called normally open type.

[0024] Specifically, as shown in Figures 1 and 2, the fluid control valve 3 includes an orifice (valve seat member) 31 having a valve seat surface 31s, a valve body 32 having a seat surface 32s that seats on the valve seat surface 31s, and a drive unit 33 that drives the valve body 32.

[0025] The orifice 31 is accommodated in the accommodation recess 21. Here, the orifice 31 is accommodated in the accommodation recess 21 so that the valve seat surface 31s faces the bottom surface of the accommodation recess 21. In this orifice 31, an inlet is formed in the valve seat surface 31s, and an internal flow path 31R communicating with the inlet is formed. Specifically, the orifice 31 is roughly disk-shaped, and has, as the internal flow path 31R, a central flow path portion CR formed in the center and a peripheral flow path portion SR provided around the central flow path portion CR. Note that the central flow path portion CR is a flow path through which a plunger mechanism 332 constituting the drive unit 33 described later is inserted.

[0026] The valve element 32 is provided movably inside the accommodating recess 21. The valve element 32 is provided inside the accommodating recess 21, between a valve seat surface 31s of the orifice 31 and the bottom surface of the accommodating recess 21.

[0027] Specifically, the valve body 32 has a seating surface 32s on the upper surface, and an outlet is formed in the seating surface 32s, and an internal flow passage 32R communicating with the outlet is formed. The outlet of the seating surface 32s and the inlet of the valve seating surface 31s are formed at positions that do not overlap with each other when the seating surface 32s is seated on the valve seating surface 31s.

[0028] The valve element 32 is supported by a support member 34 inside the accommodating recess 21 so as to be movable. The support member 34 has an annular support base 341 accommodated in the accommodating recess 21, and an elastic body 342 such as a leaf spring that is provided inside the support base 341 and supports the valve element 32. As a result, the valve element 32 is supported inside the support base 341 by the elastic body 342. Both the support base 341 and the elastic body 342 are configured to allow gas to flow through them. The lower surface of the orifice 31 is in close contact with the annular upper surface of the support base 341 to form a valve chamber S1 that accommodates the valve element 32 and communicates with the upstream flow path R1.

[0029] The driving unit 33 includes, for example, a piezo stack 331 which is an actuator formed by stacking a plurality of piezo elements, and a plunger mechanism 332 which is displaced by the expansion of the piezo stack 331.

[0030] The piezo stack 331 is housed in a casing 333, and its tip is connected to a plunger mechanism 332. The plunger mechanism 332 in this embodiment has a diaphragm member 332a and a pressing member 332b that presses the upper surface of the valve body 32 via the diaphragm member 332a. The plunger mechanism 332 is inserted into the central flow passage portion CR of the orifice 31 and comes into contact with the upper surface of the valve body 32.

[0031] The diaphragm member 332a is provided between the valve body 32 and the piezo stack 331, and is made of a thin metal plate such as stainless steel or aluminum. The diaphragm member 332a separates the flow path space in which the orifice 31 and the valve body 32 are provided from the external space in which the piezo stack 331 is provided inside the accommodating recess 21, and transmits the pressing force from the piezo stack 331 to the valve body 32.

[0032] Specifically, as shown in Fig. 3, the diaphragm member 332a has a protruding portion 332a1 protruding toward the valve body 32, and a flange portion 332a2 continuous with a base end of the protruding portion 332a1. The protruding portion 332a1 is a portion of the diaphragm member 332a protruding from a flat plate portion (here, the flange portion 332a2) toward the valve body 32. A tip portion 332x of the protruding portion 332a1 is semispherical, and the tip presses the valve body 32. In addition, the flange portion 332a2 is annular in plan view, and its peripheral portion is fixed to the accommodating recess 21 by a fixing portion 36.

[0033] Here, the protruding portion 332a1 in the diaphragm member 332a is formed by plastically deforming a metal sheet by drawing. The protruding portion 332a1 may be formed by deep drawing in which the depth is greater than the inner diameter, or may be formed by shallow drawing in which the inner diameter is greater than the depth. The metal sheet constituting the diaphragm member 332a has a thickness of 100 to 130 μm, the protruding portion 332a1 formed by drawing the metal sheet is 100 to 130 μm, and the flange portion 332a2 is 100 to 130 μm.

[0034] In addition, in the driving section 33, a sphere 332c that transmits the pressing force from the pressing member 332b to the diaphragm member 332a is provided between the diaphragm member 332a and the pressing member 332b. This sphere 332c is housed inside the protruding portion 332a1 of the diaphragm member 332a. In other words, the diameter of the sphere 332c is slightly smaller than the inner diameter of the protruding portion 332a1.

[0035] The sphere 332c is made of a ceramic material that has a smaller friction coefficient than stainless steel. The friction coefficient of stainless steel is 0.5. The sphere 332c of this embodiment is made of alumina (Al2O3), which is a ceramic material. The friction coefficient of alumina is 0.1. No coating is applied to the surface of the sphere 332c.

[0036] When a predetermined voltage is applied to the piezo stack 331, the piezo stack 331 expands, and the pressing member 332b presses the tip 332x of the protruding portion 332a1 of the diaphragm member 332a through the sphere 332c, urging the valve body 32 in the valve opening direction. Here, the valve seat surface 31s is separated from the seating surface 32s by a distance corresponding to the applied voltage, and the valve body 32 is in an open state. The upstream flow path R1 and the downstream flow path R2 communicate with each other through this gap. On the other hand, in a normal state in which no voltage is applied to the piezo stack 331, the valve body 32 is in a closed state due to the elastic force of the elastic body 342 of the support member 34.

[0037] The fluid sensor 4 is a pressure type and includes a laminar flow element 41 provided in the flow path R, a first pressure sensor 42 provided so as to be able to measure the pressure upstream of the laminar flow element 41, a second pressure sensor 43 provided so as to be able to measure the pressure downstream of the laminar flow element 41, and a flow rate calculation unit 44 that calculates the flow rate of the fluid flowing through the flow path R based on the first pressure and the second pressure measured by the first pressure sensor 42 and the second pressure sensor 43. This fluid sensor 4 is provided on the flow path R, on the upstream side or downstream side of the fluid control valve 3. Note that a sonic nozzle or the like may be used as the fluid resistance 41 instead of the laminar flow element.

[0038] The control unit 5 controls the fluid control valve 3 based on the flow rate measured by the fluid sensor 4. The control unit 5 is a computer equipped with a CPU, memory, an A / D converter, a D / A converter, and various input / output means, and controls the fluid control valve 3 by executing a fluid control program stored in the memory and cooperating with the CPU and peripheral devices.

[0039] The control unit 5 controls the aperture of the fluid control valve 3 based on a command flow rate input from outside and a measured flow rate measured by the fluid sensor 4. Specifically, the control unit 5 controls the aperture of the fluid control valve 3 so as to reduce the deviation between the command flow rate and the measured flow rate. In this embodiment, the control unit 5 performs a PID calculation on the deviation between the command flow rate and the measured flow rate, and outputs a command voltage according to the result to the drive circuit of the drive unit 33. The drive circuit applies a voltage corresponding to the input command voltage to the piezo stack 331.

[0040] <Cycle life test> Next, the results of a cycle life test on a conventional fluid control valve and the results of a cycle life test on the fluid control valve of this embodiment are shown in Fig. 4. Note that the conventional fluid control valve has a diaphragm member and a sphere made of stainless steel, and the surface of the sphere is fluorine-coated. Meanwhile, the fluid control valve of this embodiment has a diaphragm member made of stainless steel, a sphere made of alumina, and the surface of the sphere is not coated.

[0041] As can be seen from FIG. 4(a), in the conventional fluid control valve, the diaphragm member broke in all the tested valves before reaching one-fifth of the target number of times of actuation. In FIG. 4(a), the point of breakage is indicated by a cross (×). Here, when the sphere of the fluid control valve in which the diaphragm member broke was analyzed by an X-ray analyzer or the like, it was confirmed that the sphere's coating had peeled off and fretting wear or the like had occurred. On the other hand, as can be seen from FIG. 4(b), in the fluid control valve of this embodiment, in all the tested valves, cracks (breakage) of the diaphragm member did not occur even after the target number of times of actuation was actuated. In addition, in all the valves, a flow rate exceeding the required flow rate could be flowed.

[0042] <Effects of this embodiment> As described above, according to the fluid control device 100 of this embodiment, the sphere 332c housed in the protruding portion 332a1 of the diaphragm member 332a is made of a ceramic material, so the life of the fluid control valve 3 can be extended compared to when a sphere made of stainless steel is used. In addition, since the friction coefficient of the ceramic material is smaller than that of stainless steel, there is no need to apply a coating such as a fluorine coating as in the past, and the fluid control valve 3 can be constructed at low cost.

[0043] <Other embodiments> For example, in the above embodiment, the sphere 332c is made of alumina, but other ceramic materials (sintered bodies obtained by heating and baking inorganic materials) may be used. In this case, the sphere 332c may be made of, for example, an oxide-based ceramic material such as zirconia or barium titanate, a hydroxide-based ceramic material such as hydroxyapatite, a carbide-based ceramic material such as silicon carbide, a carbonate-based ceramic material, a nitride-based ceramic material such as silicon nitride, a halide-based ceramic material such as fluorite, or a phosphate-based ceramic material.

[0044] In addition, in the above embodiment, the entire sphere 332c is made of a ceramic material, but the outer shell portion that forms the surface of the sphere 332c may be made of a ceramic material.

[0045] Although the fluid sensor 4 in the above embodiment is a pressure type, it may be a thermal type. Specifically, as shown in Fig. 5, the thermal type fluid sensor 4 has a flow dividing element (resistance element) 45 provided in the flow path R, a thin tube 46 that branches from the upstream side of the flow dividing element 45 and joins the downstream side of the flow dividing element 45, two electric heating coils 47 that are wound around the thin tube 46 and to which voltages are applied so as to keep each at a constant temperature, and a flow rate calculation unit 48 that detects the voltage difference applied to each electric heating coil 47 to calculate the flow rate of the gas flowing through the flow path R. This fluid sensor 4 is provided on the upstream side or downstream side of the fluid control valve 3 in the flow path R. Note that the principle of flow rate measurement in the fluid sensor is not limited to the above and may be any method.

[0046] Furthermore, although the actuator in the above embodiment is a piezo stack, it is also possible to use, for example, a solenoid or the like.

[0047] 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. [Explanation of symbols]

[0048] 100... Fluid control device 3. Fluid control valve 4. Fluid sensor 5. Valve control section 31s...Valve seat surface (valve seat) 32 Valve body 331···Piezo stack (actuator) 332a Diaphragm member 332a1...Protrusion 332a2...Tsubabe 332c...Sphere

Claims

1. a valve body that is movable toward and away from a valve seat; an actuator that moves the valve body; a diaphragm member provided between the valve body and the actuator, the diaphragm member having a protrusion protruding toward the valve body; a sphere accommodated inside the protrusion, the actuator presses the tip of the protrusion via the sphere to move the valve body, The sphere is formed from a ceramic material.

2. The fluid control valve of claim 1 , wherein the sphere is formed from alumina.

3. 3. The fluid control valve according to claim 1, wherein the thickness of the protruding portion of the diaphragm member is 100 to 130 μm.

4. the diaphragm member has a flange portion extending outward from a base end of the protruding portion, 4. The fluid control valve according to claim 3, wherein the flange portion has a thickness of 100 to 130 μm.

5. The diaphragm member is made of a metal sheet.

5. The fluid control valve according to claim 1, wherein the protrusion is formed by plastically deforming the thin metal plate through drawing.

6. 6. The fluid control valve of claim 1, wherein the sphere has no surface coating.

7. A fluid control valve according to any one of claims 1 to 6; A fluid sensor for measuring a fluid flowing through a flow path; a valve control unit that controls the fluid control valve based on a measurement value of the fluid sensor.

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