Fluid control valve and fluid control device

Abstract

To extend a seating surface without sacrificing a drive area of a valve element and to improve mass productivity in forming the seating surface with a resin layer.SOLUTION: A fluid control valve V is configured so as to transmit power from an actuator 30 to a valve element 20 via a plunger 40, and controls a fluid to flow by causing a seating surface 21 of the valve element 20 to come into contact with and separate from a valve seat surface 11 of a valve seat 10, where the valve element 20 is formed separately from the plunger 40 and the seating surface 21 is formed of a resin layer 20b.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] As shown in Patent Document 1, a conventional fluid control valve is configured such that power from an actuator is transmitted to a valve body, and the seating surface of the valve body moves toward and away from the valve seat surface of a valve seat to control the flow of fluid.

[0003] In such a configuration, the seating surface of the valve body may be formed from a resin layer such as a fluorine-based resin in order to improve the sealing performance between the valve seat and the valve body.

[0004] When the seating surface is formed of a resin layer in this way, when attempting to close the gap between the valve seat and the valve disc, the resin layer bites into the valve seat surface, as shown in Figure 7. Due to this biting, in order to close the gap between the valve seat and the valve disc, the stroke of the valve disc by the actuator is reduced more than in a configuration in which the seating surface is made of metal.

[0005] The valve disc of Patent Document 1 has a diaphragm integrally provided around the seating surface. Therefore, if the seating surface is enlarged to improve sealing performance, the area of ​​the diaphragm is reduced accordingly. This narrows the valve disc's operating range depending on the area of ​​the diaphragm. Therefore, in a configuration in which the seating surface is formed from a resin layer, there is a risk that the stroke amount corresponding to the aforementioned penetration cannot be achieved, and there is a limit to how much the seating surface can be enlarged.

[0006] Furthermore, in the case of a valve element in which a diaphragm is integrally formed around the seating surface, if the seating surface is to be formed from a resin layer, a process such as attaching cut-out sheets of fluororesin to each valve element is required, which poses a problem of poor mass productivity. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-192243 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, the present invention has been made to solve all of the above-mentioned problems at once, and its main objective is to enlarge the seating surface without sacrificing the drive range of the valve body, and also to improve mass productivity in forming the seating surface from a resin layer. [Means for solving the problem]

[0009] In other words, the fluid control valve according to the present invention is configured so that power from an actuator is transmitted to a valve body via a plunger, and the flow of fluid is controlled by the seating surface of the valve body coming into and out of contact with the valve seat surface of a valve seat, and is characterized in that the valve body is separate from the plunger, and the seating surface is formed by a resin layer.

[0010] In such a case, the valve body is separate from the plunger, so if the diaphragm is provided on the plunger, the seating surface can be enlarged without narrowing the area of ​​the diaphragm, i.e., without sacrificing the driving range of the valve body by the diaphragm. Furthermore, because the valve body is separate from the plunger, it is possible to form seating surfaces made of a resin layer on multiple valve bodies at once, for example by attaching a single sheet of fluororesin to multiple valve bodies, thereby improving mass productivity.

[0011] An example of a mode in which the above-described effect is more pronounced is when the fluid control valve is of a so-called normally open type, that is, when no voltage is applied to the actuator, a gap is formed between the seating surface and the valve seat surface, and when a voltage is applied to the actuator, the power of the actuator causes the valve element to move closer to the valve seat, thereby reducing the flow rate. Since such a normally open type fluid control valve has a more significant problem of seat leakage in the closed state than a so-called normally closed type, the effect of improving the sealing performance by the seating surface formed by the above-mentioned resin layer is more pronounced.

[0012] In a more specific embodiment of the normally open type, the seating surface is the lower surface of the valve body.

[0013] Another embodiment is a fluid control valve of a so-called normally closed type, in which the valve element is seated on the valve seat when no voltage is applied to the actuator, and when a voltage is applied to the actuator, the power of the actuator causes the valve element to move away from the valve seat, thereby increasing the flow rate.

[0014] The resin layer is preferably a crosslinked modified fluorine-based resin. Crosslinked modified fluororesin is a fluororesin that has been crosslinked by irradiating it with ionizing radiation under specific conditions, and during crosslinking it chemically bonds with the metal itself, allowing it to adhere directly to the metal substrate, eliminating the need for an adhesive layer such as a primer, which can cause contamination. Note that crosslinking here refers to crosslinking between resins, not crosslinking between metal and resin.

[0015] In order to improve the workability of the resin layer, it is preferable that a recessed portion is formed on the surface of the valve body facing the valve seat, and that the resin layer is provided in the recessed portion.

[0016] Conventional fluid control valves employ a structure in which the valve element and plunger are in surface contact. This structure is susceptible to tolerances that arise from the machining of the valve element and valve seat, and the plunger is tilted due to the tilt of the valve element that occurs when the valve element and valve seat contact each other. Therefore, high precision is required in the manufacturing and assembly processes of each component. Furthermore, if the valve element and plunger are maintained in surface contact, fluid may accumulate in the gap, causing deterioration of the valve element and plunger. Therefore, it is preferable that the valve body and the plunger contact each other via a tilt suppression protrusion that suppresses tilt of the plunger that occurs due to contact between the valve seat and the valve body. In this case, since the valve body and plunger are in contact with each other via the tilt suppression protrusion, the influence of the tilt of the valve body that occurs due to the contact between the valve body and the valve seat is less likely to be transmitted to the plunger. This makes it easier to maintain a constant tilt of the plunger relative to the valve seat. Furthermore, fluid is less likely to remain in the gap between the valve body and the plunger, making the valve body and plunger less likely to deteriorate even if the contact state between the valve body and the plunger is maintained.

[0017] Furthermore, a fluid control device according to the present invention is characterized by including the above-described fluid control valve, and such a device can achieve the same effects as the above-described fluid control valve. [Effects of the Invention]

[0018] According to the present invention configured in this manner, the seating surface can be enlarged without sacrificing the driving range of the valve body, and mass productivity can also be improved by forming the seating surface from a resin layer. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram illustrating an overall configuration of a fluid control device according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a partial configuration of the fluid control valve of the embodiment. [Figure 3]FIG. 2 is a schematic diagram showing a plunger and a valve body of the embodiment. [Figure 4] FIG. 10 is a schematic diagram showing a partial configuration of a fluid control valve according to another embodiment. [Figure 5] FIG. 10 is a schematic diagram showing the overall configuration of a fluid control device according to another embodiment. [Figure 6] FIG. 10 is a schematic diagram showing the overall configuration of a fluid control device according to another embodiment. [Figure 7] 10 is a schematic diagram showing a state in which a resin layer forming a seating surface bites into a valve seat surface. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fluid control valve and a fluid control device using the fluid control valve according to the present invention will be described below with reference to the drawings.

[0021] The fluid control device according to this embodiment is a so-called mass flow controller used in a semiconductor manufacturing process. The fluid control device according to the present invention can be used not only in semiconductor control processes but also in other processes.

[0022] The fluid control device MFC here is a pressure type, as shown in Fig. 1. Specifically, the fluid control device MFC includes a block body B having a flow path L therein, a fluid control valve V installed in the block body B, a pair of pressure sensors PS1 and PS2 installed downstream of the fluid control valve V in the block body B, and a control unit C that feedback controls the fluid control valve V so that the flow rate value of the flow path L, calculated based on the pressure values ​​measured by the pair of pressure sensors PS1 and PS2, approaches a predetermined target value. The fluid control device MFC of this embodiment is characterized by the fluid control valve V, so the peripheral structure of the fluid control valve V will be explained first.

[0023] The block body B has, for example, a rectangular parallelepiped shape, and has a fluid control valve V and a pair of pressure sensors PS1, PS2 mounted on a predetermined surface thereof. A recessed accommodation portion B1 for mounting the fluid control valve V is also provided on a predetermined surface of the block body B, and the accommodation portion B1 divides the flow path L into an upstream flow path L1 and a downstream flow path L2. One end of the upstream flow path L1 opens on the bottom surface of the accommodation portion B1, and one end of the downstream flow path L2 opens on a side surface thereof.

[0024] The pair of pressure sensors PS1 and PS2 are connected to the upstream and downstream sides of the laminar flow element S1 in the flow path L, respectively, and are both connected to a flow rate calculation unit S2 that calculates the flow rate based on the outputs of the pair of pressure sensors PS1 and PS2. The pair of pressure sensors PS1 and PS2 are attached to a predetermined surface of the block body B in a line together with the fluid control valve V.

[0025] The control unit C has a so-called computer equipped with a CPU, memory, A / D and D / A converters, etc., and executes programs stored in the memory to realize the above-mentioned functions by the cooperation of various devices. Specifically, it feedback-controls the valve opening of the fluid control valve V so that the flow rate value calculated by the flow rate calculation unit S2 approaches a target value stored in advance in memory.

[0026] Next, the fluid control valve V of this embodiment will be described.

[0027] The fluid control valve V of this embodiment is of a so-called normally open type. Specifically, as shown in Figures 1 and 2, the fluid control valve V includes a valve seat 10 fitted into the housing portion B1 of the block body B, a valve element 20 installed so as to be movable toward and away from the valve seat 10, an actuator 30 that moves the valve element 20, a plunger 40 interposed between the valve element 20 and the actuator 30 and transmitting the power of the actuator 30 to the valve element 20, and a thin-film diaphragm 50 formed integrally with the plunger 40 and constituting a valve chamber VR. The fluid control valve V utilizes the deflection of the diaphragm 50 to transmit the power of the actuator 30 to the valve element 20 via the plunger 40 while maintaining the airtightness of the valve chamber VR.

[0028] The valve seat 10 is, for example, a block-shaped member made of metal that fits into the housing portion B1 of the block body B. When the valve seat 10 is fitted into the housing portion B1 of the block body B, the surface of the valve seat 10 that faces the same direction as a predetermined surface of the block body B forms a valve seat surface 11, and the valve seat surface 11 forms part of the inner surface of the valve chest VR. Inside the valve seat 10, a first flow path L3 that communicates with the upstream flow path L1 and multiple second flow paths L4 that communicate with the downstream flow path L2 are provided.

[0029] One end of the first flow path L3 opens to the center of the valve seat surface 11, and the other end opens to a surface facing the bottom surface of the accommodation unit B1. The second flow path L4 opens to a concentric circle centered on the center of the valve seat surface 11, and the other end opens to an outer surface facing the inner surface of the accommodation unit B1. The outer surface of the valve seat 10 is stepped, so that the side facing the valve seat surface 11 is in close contact with the inner surface of the accommodation unit B1, and the side opposite the valve seat surface 11 faces the inner surface of the accommodation unit B1 with a gap 12 between them. When the valve seat 10 is fitted into the accommodation unit B1 of the block body B, the first flow path L3 communicates with the upstream flow path L1, and the second flow path L4 communicates with the downstream flow path L2 via the gap 12.

[0030] A plurality of circulation grooves 13 are formed concentrically around the center of the valve seat surface 11. A plurality of introduction holes 14 that communicate with the second flow path L4 are arranged at equal intervals in each circulation groove 13. This allows the fluid remaining in the valve chamber VR to be evenly guided to the second flow path L4.

[0031] The valve disc 20 is a thin plate having a shape of, for example, a body of revolution, with a flat seating surface 21 facing the valve seat surface 11. The valve disc 20 is provided with a curved (specifically, spherical) tilt suppression protrusion 22 on the surface opposite the seating surface 21, which faces the diaphragm 50. The tilt suppression protrusion 22 is provided to face the plunger 40 connected to the diaphragm 50. The tilt suppression protrusion 22 is provided so that its apex is located on the central axis of the valve disc 20 (shown by a dashed line in FIG. 2 ) and is also positioned so that its apex is located on the axis of the plunger 40 (shown by a dashed line in FIG. 2 ). The valve disc 20 is supported against the valve seat surface 11 via a ring-shaped leaf spring 24 (elastic body) mounted on a support ring 23 installed on the valve seat surface 11. As a result, the leaf spring 24 repels the valve disc 20 against a pressing force against the valve seat 10.

[0032] The actuator 30 includes a piezo stack 31 made up of multiple piezo elements stacked on top of each other, and terminals for applying a voltage to the piezo stack 31, and is configured so that the piezo stack 31 expands when a voltage is applied via the terminals.

[0033] The plunger 40 is rod-shaped with one end formed integrally with the diaphragm 50 and the other end extending toward the actuator 30. In this embodiment, the other end is formed as a bulging portion 41 that bulges toward the actuator 30, and this bulging portion 41 is in direct contact with the actuator 30.

[0034] The diaphragm 50 serves to transmit the movement of the plunger 40 to the valve element 20 while maintaining the airtightness of the valve chamber VR.

[0035] As shown in FIG. 3, the fluid control valve V of this embodiment is characterized in that the above-mentioned valve body 20 is separate from the plunger 40, and the seating surface 21 of the valve body 20 is formed by a resin layer 20b.

[0036] To explain in more detail, as shown in FIG. 3, in this embodiment, a recess 42 is provided on the surface of the plunger 40 facing the valve body 20, and this recess 42 is formed as the valve chamber VR described above.

[0037] The valve body 20 of this embodiment is housed in the recess 42 described above, and its lower surface functions as the seating surface 21.

[0038] Specifically, the valve body 20 includes a metal base 20a and a resin layer 20b that covers a part of the base 20a.

[0039] The base 20a is in direct contact with the plunger 40, and the power of the actuator 30 is transmitted via this plunger 40. Here, the base 20a is provided with the tilt suppression protrusions 22 described above on the surface facing the plunger 40. Meanwhile, a recessed portion 20c is formed on the surface of the base 20a facing the valve seat 10. In other words, an annular protruding portion 20d is provided on the outer periphery of the surface of the base 20a facing the valve seat 10, and the inside of this protruding portion 20d is formed as the recessed portion 20c.

[0040] The resin layer 20b is, for example, a cross-linked modified fluororesin, specifically modified PFA. The resin layer 20b is provided in the recess 20c. One example of a method for forming the resin layer 20b is to attach a sheet of fluororesin to the base 20a and then irradiate it with electron beams under specific conditions to cross-link the fluororesin. Note that the cross-linking here refers to cross-linking between resins, not cross-linking between metal and resin. Here, as shown in FIG. 4, seating surfaces 21 made of the resin layer 20b are formed simultaneously on multiple valve bodies 20, and one of the valve bodies 20 is used in the fluid control valve V of this embodiment.

[0041] Next, the operation of the fluid control valve V according to this embodiment will be described.

[0042] The fluid control valve V is set so that the valve opening (the distance between the valve seat surface 11 of the valve seat 10 and the seating surface 21 of the valve element 20) is a predetermined value when no voltage is applied to the actuator 30. The state in which the valve opening has reached the predetermined value is the fully open state of the fluid control valve V.

[0043] Next, when a voltage is applied to the actuator 30, the actuator 30 expands. The power generated by this expansion of the actuator 30 is transmitted to the valve element 20 via the plunger 40, and the valve element 20 moves in a direction that contacts (approaches) the valve seat 10 against the pressure of the leaf spring 24. This causes the valve opening to become smaller than a predetermined value. Note that the actuator 30 expands more as the applied voltage increases, so the valve opening can be controlled by adjusting the voltage value.

[0044] When the voltage applied to the actuator 30 exceeds a predetermined value, the valve seat surface 11 of the valve seat 10 comes into contact with the seating surface 21 of the valve element 20. At this time, the valve element 20 may tilt due to the tolerances of the valve seat 10 and the valve element 20, but because the valve element 20 and the plunger 40 come into contact via the tilt suppression protrusion 22, tilt of the plunger 40 due to this tilt is suppressed.

[0045] Subsequently, when the voltage applied to the actuator 30 decreases, the actuator 30 contracts. As the actuator 30 contracts, the valve element 20 moves in a direction away from (away from) the valve seat 10 due to the pressure of the leaf spring 24. This increases the valve opening.

[0046] According to the fluid control valve V configured in this manner, the valve element 20 is separate from the plunger 40 on which the diaphragm 50 is provided, so that the seating surface 21 can be enlarged without narrowing the area of ​​the diaphragm 50, i.e., without sacrificing the driving range of the valve element 20 by the diaphragm 50. This makes it possible to ensure sealing performance while forming the seating surface 21 from the resin layer 20b.

[0047] Furthermore, since the valve body 20 is separate from the plunger 40, it is possible to form the seating surfaces 21 of the resin layer 20b on a plurality of valve bodies 20 at once, for example by attaching a single sheet of fluororesin to a plurality of valve bodies 20, thereby improving mass productivity.

[0048] Furthermore, the fluid control valve V of this embodiment is of a normally open type, and the problem of seat leakage in the closed state is more pronounced compared to a normally closed type, so the effect of improving the sealing performance by the seating surface 21 formed by the resin layer 20b described above is more pronounced.

[0049] In addition, the resin layer 20b is a cross-linked modified fluororesin, which forms a covalent bond with the metal substrate 20a upon cross-linking, and can therefore be directly adhered to the substrate 20a, eliminating the need for an adhesive layer such as a primer, which can be a source of contamination. Furthermore, since covalent bonds are stronger than coordinate bonds, ionic bonds, intermolecular forces, etc., the cross-linked modified fluororesin and the metal substrate 20a can be stably bonded with a strong bonding force. Furthermore, since the cross-linked modified fluororesin has improved elasticity compared to before modification, the seating surface 21 can be brought into contact with and separated from the valve seat surface 11 without sticking, and the responsiveness of the fluid control valve V can be expected to be improved.

[0050] Furthermore, the recessed portion 20c is formed on the surface of the base 20a facing the valve seat 10, and the resin layer 20b is provided in this recessed portion 20c, which improves processability in the process of cutting or polishing the resin layer 20b.

[0051] Furthermore, because the valve element 20 and the plunger 40 are in contact via the tilt suppression protrusion 22, the influence of the tilt of the valve element 20 that occurs due to the contact between the valve element 20 and the valve seat 10 is less likely to be transmitted to the plunger 40. This makes it easier to maintain a constant tilt of the plunger 40 relative to the valve seat 10. Furthermore, fluid is less likely to remain in the gap between the valve element 20 and the plunger 40, and even if the contact state between the valve element 20 and the plunger 40 is maintained, the valve element 20 and the plunger 40 are less likely to deteriorate.

[0052] <Other embodiments> The present invention is not limited to the above-described embodiment.

[0053] For example, in the above embodiment, a recess 42 is provided on the surface of the plunger 40 facing the valve body 20, and the valve body 20 is accommodated in the recess 42, but as shown in Figure 4, the accommodation portion B1 of the block body B may be formed deeper than in the above embodiment, and the valve body 20 may be accommodated in this accommodation portion B1. In this case, there is no need to form the recess 42 in the plunger 40, so that a plunger 40 with a conventional configuration, for example, can be used.

[0054] Furthermore, in the above embodiment, the fluid control device MFC has been described as a differential pressure type, but it may also be a thermal type, as shown in Fig. 5. Specifically, this device comprises a narrow tube T connected in parallel to a flow path L so as to guide a predetermined proportion of the fluid flowing through the flow path L, a heater H provided in the narrow tube T, and a pair of temperature sensors TS1, TS2 provided before and after the heater H. When a fluid flows through the narrow tube T, a temperature difference corresponding to the mass flow rate occurs between the two temperature sensors TS1, TS2, and the device is configured to measure the flow rate based on this temperature difference.

[0055] Furthermore, the fluid control device MFC may be one including a plurality of fluid control valves V1, V2, as shown in Fig. 6. Specifically, this device includes a resistor R through which the fluid passes, a primary pressure sensor P0, a first pressure sensor P1, a second pressure sensor P2, an upstream fluid control valve V1, and a downstream fluid control valve V2, which are installed on the outer surface of a block body B, and a control unit C that controls the upstream fluid control valve V1 and the downstream fluid control valve V2. Note that in Fig. 6, the upstream fluid control valve V1 has a configuration according to the present invention, but the downstream fluid control valve V2 may also have a configuration according to the present invention, or both the upstream fluid control valve V1 and the downstream fluid control valve V2 may have a configuration according to the present invention.

[0056] Furthermore, the resin layer 20b may be made of not only a cross-linked modified fluororesin but also various other resins, such as polyester resins such as polyamide, polycarbonate, and PBT, epoxy resin, unsaturated polyester resin, etc. In these cases, to eliminate the need for adhesive, reactive functional groups may be formed on the surface of the metal substrate 20a, for example, by using a specific agent, and the reactive functional groups may be chemically bonded to the resin by heating, for example.

[0057] The fluorine-based resin may be one selected from the group consisting of tetrafluoroethylene copolymers, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-ethylene copolymers, and polychlorotrifluoroethylene copolymers, or a mixture of two or more of these.

[0058] Furthermore, before forming the resin layer 20b on the base 20a, the surface of the base 20a may be roughened by blasting to increase the surface area, thereby making it easier to form a chemical bond between the resin layer 20b and the base 20a. Note that the chemical bond here is not limited to the above-mentioned covalent bond, but also includes a coordinate bond, an ionic bond, a bond due to intermolecular forces, and the like.

[0059] In the above embodiment, the present invention has been described by taking as an example a normally open type fluid control valve V, but the present invention can also be applied to a normally closed type fluid control valve.

[0060] In the above embodiment, a piezoelectric element (piezo stack) is used as the actuator 30 of the fluid control valve V, but a solenoid or the like may also be used.

[0061] Furthermore, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0062] MFC...Fluid control device V Fluid Control Valve 10 Valve seat 11 Valve seat surface 20 Valve body 21 Seating surface 22...Inclination suppression protrusion 20b...Resin layer 30 Actuator 40 Plunger 50 diaphragm

Claims

1. A fluid control valve configured so that power from an actuator is transmitted to a valve body via a plunger, and a seating surface of the valve body comes into contact with and separates from a valve seat surface of a valve seat to control a flow of a fluid, The valve body is separate from the plunger, an annular protrusion is provided on an outer edge of a surface of the valve body opposite to a surface facing the plunger, and a resin layer is formed over the entire flat recess formed inside the protrusion; the resin layer is formed of a resin sheet attached to the recessed portion, The fluid control valve, wherein the seating surface is formed by polishing the surface of the resin sheet.

2. When no voltage is applied to the actuator, a gap is formed between the seating surface and the valve seat surface, 2. The fluid control valve according to claim 1, wherein when a voltage is applied to the actuator, the valve element approaches the valve seat due to the power of the actuator, thereby reducing the flow rate.

3. When no voltage is applied to the actuator, the valve body is seated on the valve seat, 2. The fluid control valve according to claim 1, wherein when a voltage is applied to the actuator, the valve element moves away from the valve seat due to the power of the actuator, thereby increasing the flow rate.

4. The fluid control valve according to claim 1 , wherein the resin layer is a cross-linked modified fluororesin.

5. the valve body and the plunger are in contact with each other via a tilt suppression protrusion that suppresses tilt of the plunger that occurs due to contact between the valve seat and the valve body, 5. The fluid control valve according to claim 1, wherein the tilt suppression projection is a projection provided on an axis of the valve body and the plunger, on a surface of the valve body facing the plunger.

6. A fluid control device comprising the fluid control valve according to any one of claims 1 to 5.

Images