Fluid control valve, fluid control device, and fluid control valve manufacturing method

Abstract

The present invention improves the sealing of a fluid control valve and comprises: a valve seat 5 with a flat valve seat surface 5a; and a valve plug 6 with a flat sitting surface 6a to be seated on the valve seat surface 5a, wherein the surface hardness of a first surface, namely one of the valve seat surface 5a or the sitting surface 6a, is higher than that of a second surface, namely the other of the valve seat surface 5a or the sitting surface 6a.

Description

Fluid control valve, fluid control device, and method for manufacturing fluid control valve

[0001] The present invention relates to a fluid control valve, a fluid control device, and a method for manufacturing a fluid control valve.

[0002] 2. Description of the Related Art As disclosed in Patent Document 1, there is a conventional fluid control valve that controls a fluid by causing a flat seating surface to seat on and lift off from a flat valve seat surface.

[0003] However, in such a fluid control valve, seat leaks (leakage in the fully closed state) occur after long-term use. The causes of this include scratches and deterioration of the seating surface or valve seat surface due to repeated uneven contact between the seating surface and the valve seat, or corrosion and roughening of the valve seating surface.

[0004] Japanese Patent Application Laid-Open No. 2000-322129

[0005] SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its main object to improve the sealing performance of a fluid control valve.

[0006] That is, the fluid control valve according to the present invention comprises a valve seat having a planar valve seat surface, and a valve body having a planar seating surface that seats on the valve seat surface, and is characterized in that the surface hardness of a first surface, which is one of the valve seat surface or the seating surface, is higher than the surface hardness of a second surface, which is the other of the valve seat surface or the seating surface.

[0007] In such a fluid control valve, the surface hardness of the first surface, which is one of the valve seating surface or the seating surface, is higher than the surface hardness of the second surface, which is the other of the valve seating surface or the seating surface. This difference in hardness between the valve seating surface and the seating surface improves sealing performance. Furthermore, since the planar seating surface is seated against the planar valve seating surface, contact misalignment between them can be tolerated, further improving sealing performance. Furthermore, because both the valve seating surface and the seating surface are planar, a surface hardening process (e.g., burnishing) can be easily performed to increase the hardness of one of the surfaces. Burnishing is a process in which a tool (burnishing tool) made of a high-hardness material is pressed against a workpiece with a rough, machined surface to plastically deform and smooth the surface, thereby increasing the surface hardness.

[0008] The area of ​​the first surface is preferably larger than the area of ​​the second surface. That is, the surface hardness of the first surface, which has a larger area, is made higher than the surface hardness of the second surface, which has a smaller area. This is because the first surface, which has a larger area, is prone to being scratched when the edge of the second surface, which has a smaller area, comes into contact with the first surface, which has a larger area.

[0009] Since the valve body is a movable part driven by a drive mechanism, contact displacement of the seating surface occurs relative to the fixed valve seat surface. Here, it is desirable to make the surface hardness of the seating surface higher than that of the valve seat surface from the viewpoint of improving the durability of the valve body. Therefore, it is desirable that the first surface is the seating surface and the second surface is the valve seat surface.

[0010] Furthermore, the fluid control device of the present invention is provided with a drive mechanism having a drive member that contacts the valve body to drive the valve body, and the valve body has the seating surface and a drive force application surface that contacts the drive member, and it is desirable that the surface hardness of the drive force application surface be higher than the surface hardness of the contact surface of the drive member that contacts the valve body.

[0011] The valve body preferably has a groove formed adjacent to the seating surface. When the seating surface of the valve body is burnished, excess material is pushed out by the burnishing. This excess material enters the groove adjacent to the seating surface, preventing it from impairing sealing performance.

[0012] Furthermore, 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 set value.

[0013] Furthermore, a manufacturing method of a fluid control valve according to the present invention is a manufacturing method of a fluid control valve including a valve seat having a planar valve seat surface and a valve body having a planar seating surface that seats on the valve seat surface, and is characterized in that burnishing is performed to make the surface hardness of one of the valve seat surface or the seating surface higher than the surface hardness of the other of the valve seat surface or the seating surface.

[0014] According to the present invention as described above, the sealing performance of the fluid control valve can be improved.

[0015] Fig. 1 is a diagram schematically showing the configuration of a fluid control device according to one embodiment of the present invention; Fig. 2 is a partially enlarged cross-sectional view schematically showing the configuration of a fluid control valve (normally closed type) of the same embodiment; Fig. 3 is a plan view showing the seating surface of a valve body of the same embodiment; Fig. 4 is a cross-sectional view of the valve body of the same embodiment taken along line A-A; Fig. 5 is a partially enlarged cross-sectional view of a fluid control valve (normally open type) of a modified embodiment; Fig. 6 is a plan view showing the seating surface of a valve body of the modified embodiment.

[0016] A fluid control device according to an embodiment of 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.

[0017] <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.

[0018] 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.

[0019] The flow path block 2 is rectangular, and a flow rate sensor 31 and a fluid control valve 32 are installed on a predetermined surface. The flow path block 2 also has a recessed accommodation portion 2M for installing the fluid control valve 32 on a predetermined surface, and the accommodation portion 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 the bottom surface of the accommodation portion 2M, and one end of the downstream flow path 2R2 opens on the inner surface.

[0020] 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.

[0021] 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.

[0022] The fluid control valve 32 is provided upstream of the differential pressure flow sensor 31. Specifically, the fluid control valve 32 controls the flow rate by moving a valve element toward and away from a valve seat using a piezoelectric actuator. In this embodiment, the fluid control valve 32 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.

[0023] 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.

[0024] <Detailed Configuration of Fluid Control Valve 32> As shown in FIGS. 2 to 4 , the fluid control valve 32 of this embodiment includes a valve seat 5 having a planar valve seat surface 5 a, a valve element 6 having a planar seating surface 6 a that is in surface contact with the valve seat surface 5 a and seats on the valve seat surface 5 a, and a drive mechanism 7 that drives the valve element 6.

[0025] The valve seat 5 has a generally solid-of-rotation shape and is accommodated in the accommodation portion 2M of the flow path block 2 so that its outer surface faces the downstream flow path 2R2, as shown in Fig. 2. The valve seat 5 has an annular valve seat surface 5a formed on its bottom surface facing the bottom of the accommodation portion 2M. The valve seat 5 also has a through-hole 51 formed in the center of the inner side of the valve seat surface 5a, penetrating from the valve seat surface 5a side to the side opposite the valve seat surface 5a. The valve seat 5 also has an outlet path 52 formed therein, which allows the fluid that has flowed into the interior from the valve seat surface 5a to flow out to the downstream flow path 2R2.

[0026] The valve element 6 has a generally solid-of-rotation shape and is provided in the accommodation portion 2M of the flow path block 2, closer to the bottom than the valve seat 5, as shown in FIG. 2. The valve element 6 is supported by a support member 8 provided in the accommodation portion 2M and having an elastic body 81, such as a leaf spring. Specifically, the support member 8 supports the valve element 6 with the seating surface 6a of the valve element 6 facing the valve seat surface 5a. The valve element 6 is formed with an annular seating surface 6a corresponding to the annular valve seat surface 5a, as shown in FIG. 3. The valve element 6 is biased against the valve seat surface 5a by the elastic body 81 when no driving force is applied by the drive mechanism 7, in other words, when the seating surface 6a is seated on the valve seat surface 5a.

[0027] As shown in FIG. 2 , the drive mechanism 7 includes an actuator 71 such as a piezo stack formed by stacking multiple piezo elements, and a transmission member 72 that transmits the driving force of the actuator 71 to the valve body. The transmission member 72 has a plunger portion 721 that extends through the through-hole 51 in the valve seat 5 toward the valve body 6. In a fully closed state where no voltage is applied to the actuator 71, the tip of the plunger portion 721 is slightly spaced from the driving force application surface 6 b of the valve body 6. In an open state where voltage is applied to the actuator 71, the tip of the plunger portion 721 contacts the driving force application surface 6 b of the valve body 6. The driving force application surface 6 b is formed in the center of the valve body 6. The tip surface of the plunger portion 721 is flat and is configured to be in surface contact with the flat driving force application surface 6 b of the valve body 6.

[0028] In the fluid control valve 32 of this embodiment, the surface hardness of the first surface, which is either the valve seat surface 5a or the seating surface 6a, is higher than the surface hardness of the second surface, which is either the valve seat surface 5a or the seating surface 6a. In this embodiment, the first surface is the seating surface 6a, and the second surface is the valve seat surface 5a. The surface hardness of the seating surface 6a can be increased to, for example, a Vickers hardness of Hv 300 to Hv 500 by a surface hardening process such as burnishing. The surface hardness of the valve seat surface 5a is, for example, Hv 200. The valve seat 5 and the valve body 6 are both made of metal such as stainless steel. In this manner, in this embodiment, the magnitude relationship between the surface hardness of the seating surface 6a and the surface strength of the valve seat surface 5a is determined by a surface hardness (here, Vickers hardness) that is independent of shape.

[0029] Specifically, as shown in Fig. 3, the valve body 6 has an annular seating surface 6a formed on the surface facing the valve seating surface 5a at a position corresponding to the annular valve seating surface 5a. The area of ​​the seating surface 6a is larger than the area of ​​the valve seating surface 5a. In other words, when the seating surface 6a is seated on the valve seating surface 5a, the seating surface 6a includes the valve seating surface 5a.

[0030] The valve element 6 also has a driving force application surface 6b formed inside the seating surface 6a on the surface facing the valve seat surface 5a. The driving force application surface 6b contacts the plunger portion 721, which is the driving member of the drive mechanism 7. The surface hardness of the driving force application surface 6b is higher than the surface hardness of the contact surface of the plunger portion 721, which is the driving member, that contacts the valve element 6. The surface hardness of the driving force application surface 6b is also higher than the surface hardness of the valve element 6 other than the seating surface 6a. The surface hardness of the driving force application surface 6b can be set to, for example, Hv 300 to Hv 500 by a surface hardening process such as burnishing. In this embodiment, the surface hardness of the driving force application surface 6b is set to the same as the surface hardness of the seating surface 6a. The seating surface 6a and the driving force application surface 6b of the valve element 6 are located on the same plane, and the seating surface 6a and the driving force application surface 6b can be made to the same surface hardness by the same burnishing process. The surface hardness of the contact surface of the plunger portion 721 that comes into contact with the valve body 6 is, for example, Hv200.

[0031] Furthermore, as shown in Figures 3 and 4, the valve body 6 has annular grooves 61a and 61b formed adjacent to the annular seating surface 6a. Specifically, the annular groove 61a is formed adjacent to the radially inner side of the annular seating surface 6a, and the annular groove 61b is formed adjacent to the radially outer side of the annular seating surface 6a. Similarly, an annular groove 61c is formed adjacent to the radially outer side of the driving force application surface 6b. These grooves 61a to 61c function as relief grooves for accommodating excess material extruded by a surface hardening process such as burnishing. Note that the groove 61a adjacent to the radially inner side of the seating surface 6a and the groove 61c adjacent to the radially outer side of the driving force application surface 6b may be a common groove.

[0032] <Effects of this embodiment> With the fluid control device 100 of this embodiment configured as described above, the surface hardness of the seating surface 6a is higher than the surface hardness of the valve seating surface 5a, and thus the difference in hardness between the valve seating surface 5a and the seating surface 6a can improve sealing performance. Furthermore, because the planar seating surface 6a is seated against the planar valve seating surface 5a, misalignment between the two surfaces can be tolerated, further improving sealing performance. Furthermore, because both the valve seating surface 5a and the seating surface 6a are planar, a surface hardening process (e.g., burnishing) can be easily performed to increase the hardness of one of the surfaces.

[0033] Furthermore, since the surface hardness of the seating surface 6a of the valve element 6, which is the movable part, is made higher than the surface hardness of the valve seating surface 5a, the seating surface 6a is less likely to be damaged even if the contact area of ​​the seating surface 6a changes each time due to contact misalignment of the valve element 6. Here, since the area of ​​the seating surface 6a is made larger than the area of ​​the valve seating surface 5a, contact misalignment is permitted, and the seating surface 6a is less likely to be damaged even if the edge of the valve seating surface 5a hits the seating surface 6a.

[0034] <Other Embodiments> For example, in the above embodiment, the surface hardness of the seating surface 6a is set to be higher than the surface hardness of the valve seating surface 5a. However, the surface hardness of the valve seating surface 5a may be set to be higher than the surface hardness of the seating surface 6a.

[0035] In addition to the configuration of the above embodiment, the surface hardness of the portion of the valve body 6 that is flush with the seating surface 6a may also be increased in the same manner as the seating surface 6a.

[0036] 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.

[0037] Specifically, as shown in Fig. 5, the valve seat 5 is accommodated in the accommodation portion 2M of the flow path block 2, and the side opposite to the bottom surface facing the bottom of the accommodation portion 2M is the valve seat surface 5a. The valve seat 5 is formed with a through-hole 53 that penetrates from the valve seat surface 5a to the bottom surface, and the through-hole 53 communicates with the upstream flow path 2R1. Furthermore, on the upper surface of the valve seat 5 opposite the bottom surface, multiple annular bottomed grooves 54 are formed around the through-hole 53, and a communication hole 55 is formed that penetrates from any of the bottomed grooves 54 to the outer surface and communicates with the downstream flow path L2. The valve seat surface 5a is formed by the upper surfaces of the annular bottomed grooves 54.

[0038] The valve element 6 is provided to close the accommodation portion 2M, and is fixed to the flow path block 2 via the diaphragm portion 9. Here, the valve element 6 and the diaphragm portion 9 are integrally formed. The valve element 6 has a seating surface 6a that seats on the valve seat surface 5a as the diaphragm portion 9 elastically deforms. Note that, when no driving force is applied by the drive mechanism 7, the seating surface 6a of the diaphragm portion 9 is separated from the valve seat surface 5a. Note that the drive mechanism 7 uses an actuator 71 such as a piezo stack formed by stacking multiple piezo elements.

[0039] Even in this case, the surface hardness of the first surface, which is either the valve seat surface 5a or the seating surface 6a, is made higher than the surface hardness of the second surface, which is the other of the valve seat surface 5a or the seating surface 6a. While Fig. 6 shows an example in which the surface hardness of the seating surface 6a is made higher than the surface hardness of the valve seat surface 5a, the surface hardness of the valve seat surface 5a may also be made higher than the surface hardness of the seating surface 6a. Note that the surface hardening treatment can be performed by burnishing, as in the above embodiment.

[0040] 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 .

[0041] In the above embodiment, a piezo element (piezo stack) is used as the actuator 71 of the drive mechanism 7, but a solenoid or the like may also be used.

[0042] 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.

[0043] Furthermore, the fluid control device 100 is not limited to a pressure type or a thermal type, but may be a position type 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.

[0044] 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.

[0045] According to the present invention, the sealing performance of the fluid control valve can be improved.

[0046] REFERENCE SIGNS LIST 100: Fluid control device 2: Flow path block 2R: Internal flow path 3: Fluid control device 31: Fluid sensor 32: Fluid control valve 4: Control unit 5: Valve seat 5a: Valve seat surface 6: Valve body 6a: Seating surface 6b: Driving force acting surface 7: Driving mechanism

Claims

1. a valve seat having a planar valve seat surface; a valve body having a planar seating surface that seats on the valve seat surface, A fluid control valve, wherein a first surface which is one of the valve seat surface or the seating surface has a higher surface hardness than a second surface which is the other of the valve seat surface or the seating surface.

2. The fluid control valve of claim 1 , wherein an area of ​​the first surface is greater than an area of ​​the second surface.

3. The fluid control valve of claim 1 , wherein the first surface is the seating surface and the second surface is the valve seat surface.

4. a drive mechanism having a drive member that contacts the valve body to drive the valve body, the valve body has the seating surface and a driving force acting surface that contacts the driving member, 4. The fluid control valve according to claim 3, wherein a surface hardness of the driving force acting surface is higher than a surface hardness of a contact surface of the driving member that contacts the valve body.

5. 4. The fluid control valve of claim 3, wherein the valve body has a groove formed adjacent the seating surface.

6. A fluid control valve according to any one of claims 1 to 5; A fluid sensor for measuring a flow rate or a pressure of a fluid; A fluid control device comprising: a control unit that controls an opening degree of the fluid control valve based on a measurement value measured by the fluid sensor and a set value.

7. A method for manufacturing a fluid control valve including a valve seat having a planar valve seat surface and a valve body having a planar seat surface that seats on the valve seat surface, comprising the steps of: A method for manufacturing a fluid control valve, comprising: performing a burnishing process to make the surface hardness of one of the valve seat surface or the seating surface higher than the surface hardness of the other of the valve seat surface or the seating surface.