Fluid control valve and fluid control device

Abstract

The invention provides a fluid control valve and a fluid control device. In order to enable a fluid control valve to have a low-cost configuration and achieve a long service life, a fluid control valve is provided with: a valve body that can be brought into contact with or separated from a valve seat; an actuator that moves the valve body; a diaphragm member provided between the valve body and the actuator and having a protruding portion protruding toward the valve body; and a ball body housed inside the protruding portion, the actuator moving the valve body by pressing a front end portion of the protruding portion via the ball body, and the ball body being formed of a ceramic material.

Description

Technical Field

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

[0002] As a conventional fluid control valve, as disclosed in Patent Document 1, there is conceivable a fluid control valve in which a pressing force of an actuator is transmitted to a valve element via a diaphragm member.

[0003] Specifically, in the fluid control valve, a diaphragm member is provided between the actuator and the valve core, and the diaphragm member has a protrusion protruding toward the valve core. In addition, a ball that receives the pressing force of the actuator is provided inside the protrusion. And the actuator moves the valve core by pressing the protrusion via the ball. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Publication No. 6141663

[0005] However, conventional diaphragm members and balls are made of metal such as stainless steel, and a fluorine coating is applied to the surface of the ball in order to reduce friction and extend the life of the diaphragm members and balls.

[0006] However, due to the driving of the fluid control valve, micro-wear and the like occur, causing the fluorine coating to peel off, and repeated contact between the stainless steel metals with a high friction coefficient. As a result, the diaphragm component breaks, which is the main reason that hinders the long life of the fluid control valve. In addition, it is also possible to consider applying a high-hardness coating to the ball, but the fluid control valve becomes expensive and is not practical. Summary of the invention

[0007] Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to make a fluid control valve have an inexpensive structure and to extend its life.

[0008] That is, the fluid control valve of the present invention is characterized in that it comprises: a valve core capable of contacting or separating relative to a valve seat; an actuator for moving the valve core; a diaphragm component, which is arranged between the valve core and the actuator and has a protrusion protruding toward the valve core; and a ball housed inside the protrusion, the actuator moves the valve core by pressing the front end of the protrusion via the ball, and the ball is formed of a ceramic material.

[0009] In such a fluid control valve, the sphere housed in the protruding portion of the diaphragm member is formed of a ceramic material, so that the life of the fluid control valve can be extended compared to the case where a sphere made of metal such as stainless steel is used. In addition, since the friction coefficient of the ceramic material is smaller than that of 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 made into a cheap structure.

[0010] As a specific embodiment of the sphere, it is preferable that the sphere is formed of aluminum oxide.

[0011] In order to prevent breakage of the protrusion and to extend the life of the diaphragm member, preferably, the protrusion has a thickness of 100 to 130 μm.

[0012] As a specific embodiment of the diaphragm member, it is preferable that the diaphragm member has a flange portion extending outward from a base end of 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 preferable that the diaphragm member is made of a metal thin plate, and the protrusion is formed by plastically deforming the metal thin plate through a drawing process.

[0014] In order to make the sphere an inexpensive structure, it is preferred that no surface coating is applied to the sphere.

[0015] In addition, the fluid control device of the present invention is characterized by comprising: the above-mentioned fluid control valve; a fluid sensor for measuring the fluid flowing in the flow path; and a valve control unit for controlling the fluid control valve based on the measurement value of the fluid sensor.

[0016] As described above, according to the present invention, the fluid control valve can be configured inexpensively and its life can be prolonged. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a diagram schematically showing the configuration of a fluid control device according to an embodiment of the present invention. Figure 2 It is a partially enlarged cross-sectional view showing an orifice and a valve element of the fluid control valve according to the embodiment. Figure 3 It is a detailed cross-sectional view showing the diaphragm member according to this embodiment. Figure 4 These are the results of cycle life tests of the conventional fluid control valve and the fluid control valve of the present embodiment. Figure 5 It is a diagram schematically showing the structure of a fluid control device according to a modified embodiment. DETAILED DESCRIPTION

[0018] Hereinafter, a fluid control device according to an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, for ease of understanding, the following drawings are schematically described with appropriate omissions or exaggerations. The same components are marked with the same reference numerals and the description is appropriately omitted.

[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 for performing a semiconductor manufacturing process, for example. In addition, the fluid control device 100 can control not only gas but also liquid.

[0020] Specifically, if Figure 1 As shown, the fluid control device 100 includes: a flow path block 2, in which a flow path R is formed; a fluid control valve 3, which is used to control the gas in the flow path R; a fluid sensor 4, which measures the flow rate of the flow path R; and a control unit 5, which controls 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 a housing recess 21 for mounting the fluid control valve 3. The housing recess 21 is formed on one side of the flow path block 2 (at Figure 1 In addition, the bottom surface of the receiving recess 21 is connected to the upstream flow path R1, and the inner peripheral surface of the receiving recess 21 is connected to the downstream flow path R2. That is, the flow path R formed in the flow path block 2 is divided into the upstream flow path R1 and the downstream flow path R2 by the receiving recess 21.

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

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

[0024] Specifically, if Figure 1 as well as Figure 2 As shown, the fluid control valve 3 includes an orifice (valve seat member) 31 having a valve seat surface 31 s , a valve element 32 having a seat surface 32 s seated on the valve seat surface 31 s , and a drive unit 33 that drives the valve element 32 .

[0025] The throttle hole 31 is accommodated in the accommodation recess 21. Here, the throttle hole 31 is accommodated in the accommodation recess 21 in such a manner that the valve seat surface 31s faces the bottom surface of the accommodation recess 21. In the throttle hole 31, an inlet is formed on the valve seat surface 31s, and an internal flow path 31R connected to the inlet is formed. Specifically, the throttle hole 31 is roughly disc-shaped, and as the internal flow path 31R, it has 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. In addition, the central flow path portion CR is a flow path that is inserted through a plunger mechanism 332 constituting the drive portion 33 described later.

[0026] The valve element 32 is provided in a movable manner inside the housing recess 21. The valve element 32 is provided inside the housing recess 21 between the valve seat surface 31s of the orifice 31 and the bottom surface of the housing recess 21.

[0027] Specifically, the valve core 32 has a seat surface 32s on the upper surface, an outflow port is formed on the seat surface 32s, and an internal flow path 32R communicating with the outflow port is formed. In addition, the outflow port of the seat surface 32s and the inflow port of the valve seat surface 31s are formed at positions that do not overlap each other when the seat surface 32s is seated on the valve seat surface 31s.

[0028] In addition, the valve core 32 is supported by the support member 34 inside the storage recess 21 so as to be movable. The support member 34 comprises: an annular support base 341, which is accommodated in the storage recess 21; an elastic body 342 such as a leaf spring, which is arranged inside the support base 341 and supports the valve core 32. Thus, the valve core 32 is supported inside the support base 341 by the elastic body 342. In addition, the support base 341 and the elastic body 342 are both configured to enable gas to flow. In addition, the lower surface of the throttle hole 31 is in close contact with the annular upper surface of the support base 341, forming a valve chamber S1 that accommodates the valve core 32 and is connected to the upstream side flow path R1.

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

[0030] The piezoelectric stack 331 is housed in a housing 333, and its front end is connected to a plunger mechanism 332. The plunger mechanism 332 of this embodiment includes a diaphragm member 332a and a pressing member 332b, and the pressing member 332b presses the upper surface of the valve core 32 via the diaphragm member 332a. The plunger mechanism 332 is inserted through the central flow path CR of the orifice 31 and contacts the upper surface of the valve core 32.

[0031] The diaphragm member 332a is disposed between the valve core 32 and the piezoelectric stack 331, and is formed of a metal thin plate such as stainless steel or aluminum. The diaphragm member 332a separates the flow path space where the throttle hole 31 and the valve core 32 are disposed inside the storage recess 21 from the external space where the piezoelectric stack 331 is disposed, and transmits the pressing force from the piezoelectric stack 331 to the valve core 32.

[0032] Specifically, if Figure 3 As shown in FIG. 1 , the diaphragm member 332a includes: a protrusion 332a1 protruding toward the valve core 32; and a flange portion 332a2 continuous with the base end of the protrusion 332a1. The protrusion 332a1 is a portion of the diaphragm member 332a that protrudes from the flat plate portion (here, the flange portion 332a2) toward the valve core 32. The front end portion 332x of the protrusion 332a1 is hemispherical, and the front end thereof presses the valve core 32. In addition, the flange portion 332a2 is annular in plan view, and its peripheral edge is fixed to the housing recess 21 by the fixing portion 36.

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

[0034] In addition, in the driving part 33, a sphere 332c is provided between the diaphragm part 332a and the pressing part 332b to transmit the pressing force from the pressing part 332b to the diaphragm part 332a. The sphere 332c is accommodated inside the protruding part 332a1 of the diaphragm part 332a. That is, the diameter of the sphere 332c is slightly smaller than the inner diameter of the protruding part 332a1.

[0035] In addition, the sphere 332c is formed of a ceramic material having a smaller friction coefficient than stainless steel. In addition, the friction coefficient of stainless steel is 0.5. The sphere 332c of this embodiment is formed of alumina (Al2O3) among ceramic materials. In addition, the friction coefficient of alumina is 0.1. Here, no coating is applied to the surface of the sphere 332c.

[0036] Furthermore, if a predetermined voltage is applied to the piezoelectric stack 331, the piezoelectric stack 331 is extended, and the pressing member 332b presses the front end portion 332x of the protrusion 332a1 of the diaphragm member 332a via the spherical body 332c, thereby applying force to the valve core 32 in the valve opening direction. Here, the valve seat surface 31s is separated from the seat surface 32s by a distance corresponding to the applied voltage, and becomes an open state. Furthermore, through this gap, the upstream side flow path R1 is connected to the downstream side flow path R2. On the other hand, in a normal state where no voltage is applied to the piezoelectric stack 331, the valve core 32 is in a closed state by the elastic force of the elastic body 342 of the support member 34.

[0037] The fluid sensor 4 is a pressure sensor, and includes: a laminar flow element 41, which is provided on the flow path R; a first pressure sensor 42, which is provided to be able to measure the pressure on the upstream side of the laminar flow element 41; a second pressure sensor 43, which is provided to be able to measure the pressure on the downstream side of the laminar flow element 41; and a flow rate calculation unit 44, which 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. The fluid sensor 4 is provided on the upstream side or the downstream side of the fluid control valve 3 on the flow path R. In addition, as the fluid resistance 41, a sonic nozzle or the like may be used instead of the laminar flow element.

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

[0039] The control unit 5 controls the opening of the fluid control valve 3 based on the command flow rate input from the outside and the measured flow rate measured by the fluid sensor 4. Specifically, the control unit 5 controls the opening of the fluid control valve 3 so that the deviation between the command flow rate and the measured flow rate becomes smaller. The control unit 5 of this embodiment performs PID calculation on the deviation between the command flow rate and the measured flow rate, and outputs a command voltage corresponding 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 piezoelectric stack 331.

[0040] <Cycle life test> Then, in Figure 4 2 shows the results of the cycle life test of the conventional fluid control valve and the results of the cycle life test of the fluid control valve of the present embodiment. In addition, the diaphragm component and the ball of the conventional fluid control valve are formed of stainless steel, and a fluorine coating is applied to the surface of the ball. In addition, the diaphragm component of the fluid control valve of the present embodiment is formed of stainless steel, and the ball is formed of alumina, and no coating is applied to the surface of the ball.

[0041] from Figure 4 As shown in (a), in conventional fluid control valves, the diaphragm component broke in all the valves tested before reaching one fifth of the target number of actuations. Figure 4 In (a), the cross (×) indicates the point of fracture. Here, if the ball of the fluid control valve with a broken diaphragm is analyzed using an X-ray analyzer, it can be confirmed that the fluorine coating of the ball is peeled off and micro-wear occurs. On the other hand, Figure 4 (b) shows that in the fluid control valve of this embodiment, in all the tested valves, no rupture (breakage) of the diaphragm component occurred even after the drive was driven to the target value of the number of drives. In addition, a flow rate exceeding the required flow rate can flow through any valve.

[0042] <Effects of the present embodiment> Thus, according to the fluid control device 100 of the present embodiment, since the ball 332c housed in the protrusion 332a1 of the diaphragm member 332a is formed of a ceramic material, the life of the fluid control valve 3 can be extended compared to the case where a ball made of stainless steel is used. In addition, since the friction coefficient of the ceramic material is smaller than that of stainless steel, it is not necessary to apply a coating such as a fluorine coating as in the past, and the fluid control valve 3 can be made into an inexpensive structure.

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

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

[0045] The fluid sensor 4 of the embodiment described above is a pressure type, but it may also be a thermal type. Figure 5As shown, the thermal fluid sensor 4 comprises: a shunt element (resistance element) 45, which is arranged on the flow path R; a thin tube 46, which branches from the upstream side of the shunt element 45 and merges on the downstream side of the shunt element 45; two electric heating coils 47, which are wound on the thin tube 46 and are applied with voltage to maintain a certain temperature respectively; and a flow calculation unit 48, which detects the voltage difference applied to each electric heating coil 47 and calculates the flow rate of the gas flowing through the flow path R. The fluid sensor 4 is arranged on the upstream side or downstream side of the fluid control valve 3 on the flow path R. In addition, the flow measurement principle of the fluid sensor is not limited to the above description, and can be any method.

[0046] Furthermore, the actuator in the above embodiment is a piezoelectric stack, but for example, a solenoid or the like may be used.

[0047] Furthermore, various modifications and combinations of the embodiments are possible as long as they do not depart from the spirit of the present invention. Description of reference numerals:

[0048] 100: fluid control device; 3: fluid control valve; 4: fluid sensor; 5: valve control unit; 31s: valve seat surface (valve seat); 32: valve core; 331: piezoelectric stack (actuator); 332a: diaphragm component; 332a1: protrusion; 332a2: flange portion; 332c: sphere.

Claims

1. A fluid control valve, characterized in that: have: A valve plug capable of contacting or separating relative to a valve seat; an actuator to move the valve core; a diaphragm member, disposed between the valve core and the actuator, and having a protrusion protruding toward the valve core; as well as A spherical body is housed inside the protruding portion. The actuator moves the valve element by pressing the front end of the protrusion via the ball. The sphere is formed of a ceramic material.

2. The fluid control valve according to claim 1, characterized in that: The spheres are formed from aluminum oxide.

3. The fluid control valve according to claim 1 or 2, characterized in that: In the diaphragm member, the protrusion has a thickness of 100 to 130 μm.

4. The fluid control valve according to claim 3, characterized in that: The diaphragm member has a flange portion extending outward from a base end of the protrusion portion relative to the protrusion portion. The flange portion has a thickness of 100 to 130 μm.

5. The fluid control valve according to any one of claims 1 to 4, characterized in that: The diaphragm member is made of a metal sheet. The protrusion is formed by plastically deforming the metal thin plate through a drawing process.

6. The fluid control valve according to any one of claims 1 to 5, characterized in that: No surface coating was applied to the spheres.

7. A fluid control device, characterized in that: have: The fluid control valve according to any one of claims 1 to 6; a fluid sensor to measure a fluid flowing in the flow path; and The valve control unit controls the fluid control valve based on the measurement value of the fluid sensor.

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