Diaphragm valve, valve opening adjustment method, and clamp member for valve opening adjustment

Abstract

To provide a diaphragm valve which can facilitate fine adjustment of a valve opening, and to provide a valve opening adjustment method and a clamp member for adjustment of the valve opening.SOLUTION: A diaphragm valve 1 includes: a valve body 3 including a passage 2 therein; a diaphragm valve body 4 for opening and closing the passage 2; a piezo actuator 5 for opening and closing the diaphragm valve body 4; a cylindrical case 6 which is supported at one end side by the valve body 3 and houses the piezo actuator 5 and in which a box nut 7 for adjusting a valve opening of the diaphragm valve body 4 is threadedly engaged with the other end side; and a clamp member 25 having fastening screws 25c, 25d which connect a pair of clamp pieces 25a, 25b, configured to sandwich an outer peripheral surface of the cylindrical case, and are used to adjust a force of the pair of clamp pieces 25a, 25b for fastening the cylindrical case 6.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a diaphragm valve, a method for adjusting the valve opening degree of the valve, and a clamping member for adjusting the valve opening degree, and particularly relates to a piezoelectrically driven metal diaphragm valve.

Background Art

[0002] Conventionally, as this type of piezoelectrically driven metal diaphragm valve, a diaphragm valve that opens and closes a metal diaphragm valve body using a piezo actuator is known (Patent Documents 1, 2, etc.). A valve using a piezo actuator is excellent in high-speed responsiveness to a control signal and can open and close the valve in the sub-micron order to the micron order, so that a minute flow rate can be controlled with high precision. In particular, it is suitable for applications that require precise control of a minute flow rate of a process gas as semiconductor miniaturization progresses, such as semiconductor manufacturing equipment.

[0003] Figs. 1 and 2 show an example of a conventional diaphragm valve. The diaphragm valve 1 shown in Fig. 1 includes a valve body 3 having a flow path 2 and a valve seat 2a provided in the flow path 2, a diaphragm valve body 4 that abuts and separates from the valve seat 2a, a piezo actuator 5 for abutting and separating the diaphragm valve body 4 from the valve seat 2a, and a metal cylindrical case 6 in which the piezo actuator 5 is housed. One end side (the lower end side in the figure) of the cylindrical case 6 is supported by the valve body 3, and a cap nut 7 for adjusting the valve opening degree is screwed to the other end side (the upper end side in the figure).

[0004] A diaphragm presser 8 is fixed to the lower end of the cylindrical case 6. The diaphragm valve body 4 has a reverse dish shape with a slightly bulging central portion. The peripheral edge of the diaphragm valve body 4 is press-fixed by a presser adapter 9. The presser adapter 9 is fixed to the valve body 3 by a base presser 11 via a split base 10. The base presser 11 is screwed to the valve body 3. The base presser 11 is cylindrical, and the lower part of the cylindrical case 6 is inserted therein.

[0005] As shown in Figures 3 and 4, the split base 10 is divided into a pair of split base pieces 10a and 10b having the same shape. The split base pieces 10a and 10b include a flange portion 10c that is pressed and fixed by a base retainer 11, and a support portion 10d that supports the piezo actuator 5 via a receiving plate 12 (Figure 1) within the cylindrical case 6. As shown in Figure 5, the cylindrical case 6 includes an upper large-diameter portion 6a and a lower small-diameter portion 6b. The lower small-diameter portion 6b has holes 6c on both the left and right sides (only one side is shown in the figure) into which the support portion 10d (Figure 4) is inserted. The piezo actuator 5 has a hemispherical projection 13 at its lower end. The receiving plate 12 has a recess on its upper surface that receives the hemispherical projection 13, and its lower surface rests on the support portion 10d.

[0006] Multiple disc springs 14 are stacked and housed between the support portion 10d and the bottom surface of the cylindrical case 6. Due to the elastic force of the disc springs 14, the cylindrical case 6 is pushed downward in Figure 1, pushing against the diaphragm valve body 4. The diaphragm valve body 4 is pushed by the diaphragm retainer 8, causing its central portion to deform as shown in Figure 1, and it comes into contact with the valve seat 2a provided in the flow path 2, closing the flow path 2.

[0007] When current is applied to the piezo actuator 5, it extends and lifts the cylindrical case 6 against the elastic force of the disc spring 14. As a result, the diaphragm valve body 4 elastically returns to its original inverted disc shape and separates from the valve seat 2a, opening the flow path 2.

[0008] A cap nut 7 and a lock nut 15 for locking the cap nut 7 are screwed into the threaded portion 6d on the upper outer circumference of the cylindrical case 6. A bearing 16 and a bearing holder 17 are interposed between the cap nut 7 and the piezo actuator 5. The cap nut 7 has a hole 7a for pulling out the lead wire 5a of the piezo actuator 5.

[0009] A cap nut 7 is screwed onto the threaded portion 6d of the cylindrical case 6, and the cap nut 7 is tightened to fix the piezo actuator 5 inside the cylindrical case 6 while applying a pressing force to it.

[0010] With the cap nut 7 tightened, applying pressure to the piezo actuator 5 inside the cylindrical case 6, increasing the amount the cap nut 7 is screwed in will lift the cylindrical case 6 against the disc spring 14, and conversely, decreasing the amount the cap nut 7 is screwed in will cause the cylindrical case 6 to lower due to the elastic force of the disc spring 14.

[0011] The valve opening is adjusted by applying a predetermined voltage to the piezo actuator 5 and measuring the flow rate of the fluid flowing through the flow path 2 using a known measurement method, while simultaneously adjusting the screw-in amount of the cap nut 7 with a wrench, so that the desired valve opening is obtained and the desired flow rate is achieved when a predetermined voltage is applied to the piezo actuator 5.

[0012] The diaphragm valve 1 in Figure 1 is a so-called normally closed valve (Patent Document 1). A conventional normally open type diaphragm valve (Patent Document 2) will be described below with reference to Figure 6.

[0013] The diaphragm valve 1 shown in Figure 6 comprises a valve body 3 having a flow path 2 and a valve seat 2a provided in the flow path 2, a diaphragm valve body 4 that contacts and separates from the valve seat 2a, a piezo actuator 5 for contacting and separating the diaphragm valve body 4 from the valve seat 2a, and a cylindrical metal case 6 housing the piezo actuator 5. The cylindrical case 6 is supported at one end (the lower end in the figure) by the valve body 3, and a cap nut 7 for adjusting the valve opening is screwed to the other end (the upper end in the figure). The cap nut 7 is locked by a lock nut 15.

[0014] The cylindrical case 6 is fixed to the valve body 3 by a bonnet 19 via a retaining adapter 9 and a guide body 18. The diaphragm retainer 8 is housed within the guide body 18 so as to be able to slide up and down. A ball 21 is interposed between the lower support base 20, which supports the lower part of the piezo actuator 5, and the diaphragm retainer 8. A ball 23 is also interposed between the upper support base 22, which is placed on top of the piezo actuator 5, and the piezo actuator 5. The upper support base 22 is housed within a cap nut 7. Reference numeral 24 indicates a protective case.

[0015] The piezo actuator 5 extends when a predetermined voltage is applied, and closes the flow path 2 by pressing the diaphragm valve body 4 against the valve seat 2a via the diaphragm retainer 8. Figure 6 shows the state when voltage is applied to the piezo actuator 5. When the application of voltage to the piezo actuator 5 is stopped, the piezo actuator 5 returns from the extended state to its original shortened state, and the diaphragm valve body 4 returns to the open state due to its retained elasticity.

[0016] Similar to the normally closed type, the valve opening degree of the normally open type is adjusted by adjusting the amount the cap nut 7 is tightened. [Prior art documents] [Patent Documents]

[0017] [Patent Document 1] Japanese Patent Publication No. 2003-120832 [Patent Document 2] Japanese Patent Application Publication No. 7-310842 [Overview of the project] [Problems that the invention aims to solve]

[0018] Traditionally, the valve opening was adjusted by rotating a cap nut using a wrench. However, the full stroke of the diaphragm valve is only a few tens of micrometers, making it difficult to fine-tune the valve opening during initial setup.

[0019] Therefore, the main objective of the present invention is to provide a diaphragm valve, a valve opening adjustment method, and a clamp member for valve opening adjustment that can easily fine-tune the valve opening. [Means for solving the problem]

[0020] To solve the above problems, one embodiment of the diaphragm valve according to the present invention comprises a valve body having a flow path and a valve seat provided in the flow path, a diaphragm valve body that abuts against and separates from the valve seat, a piezo actuator for abutting against and separating the diaphragm valve body from the valve seat, a cylindrical case having one end supported by the valve body and housing the piezo actuator, with a cap nut screwed to the other end for adjusting the valve opening of the diaphragm valve body, and a clamp member having a pair of clamp pieces that sandwich the outer circumferential surface of the cylindrical case and a tightening screw that connects the pair of clamp pieces and adjusts the force with which the pair of clamp pieces tighten the cylindrical case.

[0021] The aforementioned tightening screws may be provided on both sides of the cylindrical case.

[0022] One end of the pair of clamp pieces may be hinged together, and the other end of the pair may be connected by the tightening screw.

[0023] Furthermore, one aspect of the valve opening adjustment method according to the present invention includes a rough adjustment step of roughly adjusting the valve opening of the diaphragm valve body by adjusting the amount the cap nut is screwed in, and a fine adjustment step of finely adjusting the valve opening of the diaphragm valve body after the rough adjustment step by tightening the tightening screw of the clamp member with a predetermined torque to elastically deform and extend the cylindrical case.

[0024] Also, one aspect of the clamp member for valve opening degree adjustment according to the present invention is a clamp member for valve opening degree adjustment of a diaphragm valve having a cylindrical case in which a piezoelectric actuator is housed and a cap nut for adjusting the valve opening degree is screwed. The clamp member includes a pair of clamp pieces that sandwich the outer peripheral surface of the cylindrical case, and a tightening screw that connects the pair of clamp pieces and adjusts the force for tightening the cylindrical case by the pair of clamp pieces.

Effects of the Invention

[0025] By tightening the outer peripheral surface of the cylindrical case with the clamp member according to the present invention, the cylindrical case elastically deforms and extends in its length direction. Utilizing the fact that the valve opening degree of the diaphragm valve body changes by the amount that the cylindrical case extends, the valve opening degree can be finely adjusted. Since the tightening force of the clamp member can be adjusted by turning the tightening screw, fine adjustment of the valve opening degree becomes easy.

Brief Description of the Drawings

[0026] [Figure 1] It is a longitudinal front view showing a conventional normally closed type diaphragm valve. [Figure 2] It is a longitudinal front view showing a state where the cap nut of the diaphragm valve of FIG. 1 is removed. [Figure 3] It is a perspective view showing a split base which is a component of the diaphragm valve of FIG. 1. [Figure 4] It is a perspective view showing the split base separated from FIG. 3. [Figure 5] It is a perspective view showing a cylindrical case which is a component of the diaphragm valve of FIG. 1. [Figure 6] It is a longitudinal front view showing a conventional normally open type diaphragm valve. [Figure 7] It is a longitudinal front view showing an embodiment of the diaphragm valve according to the present invention. [Figure 8] It is a perspective view showing a clamp member which is a component of the diaphragm valve of FIG. 7. [Figure 9]Figure 8 is a perspective view showing the clamp member with the tightening screw screwed in. [Figure 10] Figure 7 is a cross-sectional view of XX. [Figure 11] Figure 8 is a cross-sectional view showing the disassembled state of the clamp member. [Figure 12] A perspective view showing a modified version of the clamp member, which is a component of the present invention. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described below with reference to Figures 7 to 12. Note that the above-described embodiments include the prior art, and identical or similar components are denoted by the same reference numerals to avoid redundant explanations.

[0028] Referring to Figure 7, the diaphragm valve 1 comprises a valve body 3 having a flow path 2 and a valve seat 2a provided in the flow path 2, a diaphragm valve body 4 that contacts and separates from the valve seat 2a, a piezo actuator 5 for contacting and separating the diaphragm valve body 4 from the valve seat 2a, a cylindrical case 6 with one end supported by the valve body 3 and housing the piezo actuator 5, and a cap nut 7 for adjusting the valve opening of the diaphragm valve body 4 screwed to the other end, and a clamp member 25 that clamps the outer circumferential surface of the cylindrical case 6.

[0029] The clamp member 25, as shown in Figures 8 to 11, comprises a pair of clamp pieces 25a and 25b that clamp the outer surface of the cylindrical case 6, and tightening screws 25c and 25d that connect the pair of clamp pieces 25a and 25b and adjust the force with which the pair of clamp pieces 25a and 25b tighten the cylindrical case 6.

[0030] The tightening screws 25c and 25d in the illustrated example are screwed parallel to each other on both sides of the cylindrical case 6. The clamp pieces 25a and 25b have semicircular inner surfaces 25a1 and 25b1 that abut along the outer circumferential surface of the cylindrical case 6. One clamp piece 25b has counterbore holes 25b2 and 25b3 at both ends. The other clamp piece 25a has screw holes 25a2 and 25a3 at both ends. The pair of clamp pieces 25a and 25b are connected by passing the tightening screws 25c and 25d through the counterbore holes 25b2 and 25b3 and screwing them into the screw holes 25a2 and 25a3. The pair of clamp pieces 25a and 25b are designed so that they do not come into contact with each other, but have a gap G between them, with their semicircular inner surfaces 25a1 and 25b1 abutting against the outer circumferential surface of the cylindrical case 6. By screwing the tightening screws 25c and 25d into the screw holes 25a2 and 25a3, the pair of clamping pieces 25a and 25b tighten around the outer surface of the cylindrical case 6, and a radially inward compressive force acts on the outer surface of the cylindrical case 6.

[0031] The valve opening of the diaphragm valve body 4 is adjusted using the following procedure. In the normally closed type shown in Figure 7, the valve opening is adjusted so that a predetermined flow rate is supplied when a predetermined voltage is applied to the piezo actuator 5. Therefore, while fluid is supplied to the flow path 2, the flow rate that has passed through the flow path 2 is measured. The flow rate can be measured using known measuring means.

[0032] The valve opening is first adjusted using the cap nut 7. At this time, the clamp member 25 has its tightening screws 25c and 25d loosened, and the cylindrical case 6 is not being tightened.

[0033] When the cap nut 7 is not screwed into the threaded portion 6d of the cylindrical case 6 (Figure 2), the cylindrical case 6 is pushed down by the elastic force of the disc spring 14. At this time, the diaphragm valve body 4 is pressed by the diaphragm retainer 8, abuts against the valve seat 2a, and closes the flow path 2.

[0034] Screw the cap nut 7 into the threaded portion 6d of the cylindrical case 6 until it touches the piezo actuator 5. Apply a predetermined voltage to the piezo actuator 5 to open the diaphragm valve body 4. In this open state, adjust the amount the cap nut 7 is screwed into the threaded portion 6d. By increasing or decreasing the amount the cap nut 7 is screwed in, the cylindrical case 6 moves up and down, increasing or decreasing the valve opening. A wrench (not shown) is used to turn the cap nut 7. A digital torque wrench can be used. Adjusting the valve opening using the cap nut 7 with a wrench is not suitable for fine adjustment, but it is suitable for rough adjustment. By adjusting the amount the cap nut 7 is screwed in, the valve is roughly adjusted to a value close to the target valve opening, i.e., the target flow rate for the applied voltage.

[0035] After the rough adjustment described above, fine adjustment is made using the clamp member 25. When the tightening screws 25c and 25d of the clamp member 25 are screwed into the screw holes 25a2 and 25a3, the outer surface of the cylindrical case 6 is tightened radially inward by the clamp pieces 25a and 25b. When the outer surface of the cylindrical case 6 is tightened radially inward, it stretches slightly in the height direction due to elastic deformation. The elongation of the cylindrical case 6 due to elastic deformation in the illustrated example is, for example, several micrometers.

[0036] The diaphragm valve 1 shown in the illustration has a full stroke of 55 micrometers. For example, when the cylindrical case 6 extends by 3 micrometers, the cylindrical case 6 is pushed down by the disc spring 14 by about 5%. When the cylindrical case 6 is pushed down, the valve opening of the diaphragm valve body 4 decreases, and the flow rate decreases.

[0037] When the cylindrical case 6 is stretched by tightening the clamp member 25, turning the tightening screws 25c and 25d to loosen the clamping force reduces the stretch, compresses the disc spring 14, lifts the cylindrical case 6, increases the valve opening, and increases the flow rate.

[0038] As described above, the valve opening can be finely adjusted to the desired flow rate by increasing or decreasing the amount that the tightening screws 25c and 25d are screwed into the screw holes 25a2 and 25a3. Furthermore, there is a correlation between the tightening torque and the amount of elongation of the cylindrical case 6, i.e., the valve opening, and this correlation can be collected as data in advance and used during fine adjustment. In this case, the tightening torque can be adjusted using a digital torque driver (not shown). Since the valve opening is finely adjusted by turning the tightening screws 25c and 25d with a driver, it is easier to fine-tune compared to turning the cap nut 7 with a torque wrench.

[0039] Figure 12 shows a modified version of the clamp member 25. In the clamp member 25 shown in Figure 12, one end of a pair of clamp pieces 25a and 25b is connected by a hinge 25e, and the other end is connected by a tightening screw 25c. The other configurations of the clamp member 25 in Figure 12 are the same as those of the clamp member in Figure 8. Fine adjustment of the valve opening degree using the clamp member 25 in Figure 12 can be performed in the same way as with the clamp member in Figure 8.

[0040] In the above embodiment, a normally closed type diaphragm valve was described, but by attaching the clamp member 25 shown in Figure 8 or Figure 12 to the cylindrical case 6 of the conventional normally open type diaphragm valve 1 shown in Figure 6, the valve opening can be adjusted in the same way as the normally closed type. In the normally open type, when the piezo actuator 5 is not energized, the diaphragm valve body 4 separates from the valve seat 2a, and the valve is in the open state. As the voltage applied to the piezo actuator 5 is increased, the diaphragm retainer 8 descends accordingly, and finally the flow path 2 is blocked. Therefore, in order to obtain a predetermined flow rate at a predetermined voltage, the valve opening can be roughly adjusted by adjusting the cap nut 7 in the same way as the normally closed type described above, and the valve opening can be finely adjusted by adjusting the tightening force of the clamp member 25.

[0041] The present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention. For example, in the above embodiments, screw holes 25a2 and 25a3 are formed in one clamp piece 25a, but one clamp piece may be left as a through hole without screw holes, and the length of the tightening screws 25c and 25d may be set to a length that protrudes from the clamp piece 25a, and the protruding portion may be fastened with a nut. [Explanation of symbols]

[0042] 1. Diaphragm valve 2 Flow Channels 3 Valve Body 4. Diaphragm valve body 5. Piezo actuator 6. Cylindrical case 25 Clamp member 25a, 25b Clamp pieces 25c, 25d tightening screws

Claims

1. A valve body having a flow path and a valve seat provided in the flow path, A diaphragm valve body that contacts and separates from the valve seat, A piezo actuator for moving the diaphragm valve body toward and away from the valve seat, A cylindrical case is supported at one end by the valve body, housing the piezo actuator, and having a cap nut screwed onto the other end for adjusting the valve opening of the diaphragm valve body. A clamping member comprising a pair of clamping pieces that clamp the outer surface of the cylindrical case, and a tightening screw that connects the pair of clamping pieces and adjusts the force with which the pair of clamping pieces tighten the cylindrical case, A diaphragm valve equipped with [a specific feature].

2. The diaphragm valve according to claim 1, wherein the tightening screws are provided on both sides of the cylindrical case.

3. The diaphragm valve according to claim 1, wherein one end of the pair of clamp pieces is hinged and the other end of the pair is connected by the tightening screw.

4. A method for adjusting the valve opening of a diaphragm valve according to any one of claims 1 to 3, A rough adjustment step is performed to roughly adjust the valve opening of the diaphragm valve body by adjusting the screwing depth of the cap nut, After the rough adjustment step, a fine adjustment step is performed to finely adjust the valve opening of the diaphragm valve body by tightening the tightening screw of the clamp member to a predetermined torque, thereby elastically deforming and extending the cylindrical case. A method for adjusting the valve opening of a diaphragm valve, including [a specific component].

5. A clamp member for adjusting the valve opening of a diaphragm valve, which has a cylindrical case that houses a piezo actuator and has a cap nut screwed onto it for adjusting the valve opening, A pair of clamping pieces that sandwich the outer surface of the cylindrical case, A tightening screw for connecting the pair of clamp pieces and for adjusting the force with which the pair of clamp pieces tighten the cylindrical case, The valve opening adjustment clamp member comprises the aforementioned clamp member.

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