Diaphragm valve

Abstract

To provide a diaphragm valve facilitating positioning of a diaphragm presser and capable of suppressing seat leakage.SOLUTION: An end surface of a stem 4 abutting on a diaphragm presser 6 is a plane surface, and an end surface of the diaphragm presser 6 abutting on the stem 4 is a curved surface in which a center of a column becomes the highest portion 6a. An inner peripheral surface of a presser adaptor 5 and an outer peripheral surface of the diaphragm presser 6 are in slide contact with each other, and an inner peripheral surface of a hood 7 and an outer peripheral surface of the diaphragm presser 6 do not contact with each other.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a diaphragm valve, and particularly to a diaphragm valve suitable for controlling the flow rate of process gas for semiconductor manufacturing.

Background Art

[0002] Conventionally, as a flow rate control for process gas for semiconductor manufacturing, a diaphragm valve provided with a diaphragm has been known (Patent Documents 1, 2, etc.). In this type of diaphragm valve, it is necessary to position the diaphragm retainer so that the central axis of the diaphragm retainer and the central axis of the valve seat are in a straight line. If there is an axial misalignment, it may cause seat leakage, particle generation, and durability degradation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] As shown in an example of Patent Document 1, when the diaphragm retainer is provided integrally with the actuator, the diaphragm retainer becomes longer in the axial direction, which causes the inclination of the diaphragm retainer. Also, as shown in an example of Patent Document 2, when a stem for transmitting the thrust from the diaphragm retainer and the actuator to the diaphragm retainer is provided separately, the axial misalignment of the stem affects the axial misalignment of the diaphragm retainer. Due to the axial misalignment of the diaphragm retainer, the diaphragm is pressed in a deformed state, inducing seat leakage and particle generation due to one-sided contact with the sheet-like valve seat.

Means for Solving the Problems

[0005] The present inventors aim to provide a diaphragm valve that allows for easy positioning of the diaphragm retainer and can suppress seat leaks.

[0006] The diaphragm valve according to the present invention comprises a valve body having a valve chamber that forms a valve seat and a fluid passage communicating with the valve chamber; a diaphragm that opens and closes the fluid passage by contacting and separating from the valve seat; a stem that is actuated by an actuator; a cylindrical diaphragm retainer positioned between the stem and the diaphragm, which moves with the movement of the stem to deform the diaphragm; a hollow bonnet fixed to the valve body, in which the stem and the diaphragm retainer are positioned; and the bonnet A diaphragm valve having an annular retaining adapter interposed between the stem and the valve body, which presses the peripheral edge of the diaphragm to fix the diaphragm to the valve body, wherein the end face of the stem that abuts the diaphragm retainer is flat, the end face of the diaphragm retainer that abuts the stem is a curved surface with the center of the cylinder being its highest point, the inner circumferential surface of the retaining adapter and the outer circumferential surface of the diaphragm retainer are in sliding contact, and the inner circumferential surface of the bonnet and the outer circumferential surface of the diaphragm retainer do not come into contact.

[0007] The diaphragm retainer may consist of a bottomed cylindrical lid with a curved surface whose side surface slides against the inner circumferential surface of the retaining adapter and whose one end surface abuts against the stem, and a diaphragm retainer body that fits into a recess on the other end surface of the lid.

[0008] In one embodiment, the material of the diaphragm retainer can be Invar material. [Effects of the Invention]

[0009] According to the present invention, the inner surface of the retaining adapter and the outer surface of the diaphragm retainer slide against each other, so that the central axis of the diaphragm retainer and the central axis of the valve seat are aligned, thereby preventing seat leaks.

[0010] Furthermore, by making the end face of the stem that contacts the diaphragm retainer a flat surface, and the end face of the diaphragm retainer that contacts the stem a curved surface with the center of the cylinder being its highest point, the force applied from the stem to the diaphragm retainer is limited to the axial direction only. This does not hinder the sliding of the diaphragm retainer against the retaining adapter, thus preventing a decrease in durability and the generation of particles.

[0011] Furthermore, by preventing contact between the inner surface of the hood and the outer surface of the diaphragm retainer, it is possible to prevent the circumferential force applied to the diaphragm retainer due to misalignment of the hood axis, which can cause the diaphragm retainer to twist, leading to reduced durability and the generation of particles. [Brief explanation of the drawing]

[0012] [Figure 1] This is a partially cutaway cross-sectional view showing the internal structure of the valve according to this embodiment. [Figure 2] This is an enlarged partial cross-sectional view of the key parts of the internal structure of the valve. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to the embodiments described below.

[0014] The diaphragm valve 1 comprises a valve body 2 having a valve chamber 21 and a fluid passage 20 formed therein, a valve seat 22 formed in the valve chamber 21, a diaphragm 3 positioned in the valve chamber 21 that opens and closes the fluid passage 20 by contacting or separating from the valve seat 22, an actuator that moves the stem 4 to bring the diaphragm 3 into contact with or separate from the valve seat 22, a cylindrical diaphragm retainer 6 that deforms the diaphragm 3 as the stem 4 moves up and down, a bonnet in which the stem 4 and the diaphragm retainer 6 are positioned, and a retaining adapter 5 that is pressed against the valve body 2 by the bonnet 7 and fixes the diaphragm 3 to the valve body 2 by sandwiching the peripheral edge of the diaphragm 3 between itself and the valve body.

[0015] The valve body 2 is made of a metal such as stainless steel, and a valve chamber 21, which is a cylindrical recess formed in the valve body 2, is formed therein. An annular projection, a valve seat 22, is formed on the bottom surface of the cylindrical recess, sharing the same central axis as the cylindrical recess, and an inlet fluid passage and an outlet fluid passage open on the inside and outside of the valve seat 22. Note that the opening positions of the inlet fluid passage and the outlet fluid passage may be reversed.

[0016] The diaphragm 3 is formed in a circular dish shape from an ultra-thin metal plate. The base material of the diaphragm 3 is not particularly limited, but in this embodiment, it is formed from a metal (including alloys) such as Spron. The size of the diaphragm 35 is also not particularly limited, but for example, it can have a diameter of 5 to 50 mm and a thickness of 20 to 400 μm.

[0017] The actuator is not particularly limited as long as it can move the stem 4 up and down, and a solenoid actuator or the like can be used, but in this embodiment a piezo actuator is used. In the piezo actuator, when a voltage is applied to the piezo element, the piezo element extends, and the stem 4 and diaphragm retainer 6 move up and down as shown in the figure, thereby deforming the diaphragm 3. This embodiment is a normally closed type diaphragm valve, in which the stem 4 is pressed downward by the coil spring and the diaphragm 3 contacts the valve seat 22, closing the fluid passage 20. By applying a voltage to the piezo element, the stem 4 is moved upward against the biasing force of the coil spring, and the fluid passage 20 is opened. Note that the diaphragm valve is not limited to the normally closed type, and a normally open type in which the fluid passage is open in the steady state may also be used.

[0018] The bonnet 7 is a hollow cylindrical member interposed between the actuator and the valve body 2, and the stem 4 and the diaphragm retainer 6 are disposed inside it. The lower part of the bonnet 7 is inserted into the valve chamber 21 and fixed to the valve body 2. In the figure, the flange of the bonnet 7 and the valve body 2 are fixed by bolts, but it may also be fixed by threading the outer periphery of the lower part of the bonnet 7 and screwing it to the valve body 2. A retainer adapter 5 is provided at the lower end of the bonnet 7, and the peripheral edge of the diaphragm 3 is sandwiched between the retainer adapter 5 and the valve body 2. Here, the outer diameter of the retainer adapter 5 is substantially the same as or slightly smaller than the inner diameter of the cylindrical concave portion of the valve body 2. The retainer adapter 5 is restricted from moving in the circumferential direction and is integrated with the valve body 2 by being pressed from above by the bonnet 7.

[0019] The diaphragm retainer 6 is a cylindrical member that moves as the stem 4 moves and presses the diaphragm 3. The outer peripheral surface of the diaphragm retainer 6 is in sliding contact with the inner peripheral surface of the retainer adapter 5. The outer diameter of the diaphragm retainer 6 and the inner diameter of the retainer adapter are not particularly limited, but in this embodiment, both are designed to be about 11 mm, and a gap of 0.03 mm to 0.2 mm is provided between the diaphragm retainer and the retainer adapter, so that a so-called slidable state is achieved. As the material of the diaphragm retainer 6, in order to suppress the influence of temperature change, it is desirable to use a material with a small coefficient of thermal expansion, for example, an Invar material.

[0020] Also, a bottomed cylindrical lid body 61 having a curved surface that abuts against the stem 4 and a diaphragm retainer main body 60 that is fitted into the recess on the other end surface of the lid body are combined. This is because it is necessary to change the material on the side that prevents sticking during the sliding of the diaphragm retainer 6 and on the lower surface where stress concentration on the diaphragm 3 is desired to be alleviated. An Invar material can be used for the lid body 61 and a resin material can be used for the diaphragm retainer main body 60, but a combination of the same Invar material may also be used, or they may be integrally formed of the same material.

[0021] The lower surface of the diaphragm retainer 6 is curved, so that when the diaphragm is pressed, the contact with the diaphragm 3 expands from point contact to surface contact. The upper part of the diaphragm retainer 6 protrudes from the retaining adapter 5 and faces the inner surface of the bonnet 7, but a gap is provided between the bonnet 7 and the diaphragm retainer 6 so that they do not come into contact. Because a gap is provided between the bonnet 7 and the diaphragm retainer 6, even if the axis of the bonnet 7 is misaligned with the axis of the diaphragm retainer 6, the bonnet 7 and the diaphragm retainer 6 will not come into contact and will not hinder the operation of the diaphragm retainer. In this embodiment, the outer diameter of the diaphragm retainer 6 is about 11 mm, and a gap of about 0.5 mm to 1.5 mm is provided between it and the inner diameter of the bonnet 7 so that they do not slide against each other.

[0022] The stem 4 is connected to the actuator and moves with the actuator, having a cylindrical portion that presses against the diaphragm retainer 6. The outer diameter of the stem 4 is larger than the outer diameter of the diaphragm retainer 6, and its axis is provided by the bonnet 7. The lower end surface of the stem 4 is flat and is pressed against the upper end surface of the diaphragm retainer 6.

[0023] The upper end surface of the diaphragm retainer 6 is a curved surface with the center of the cylinder being the highest part 6a, and it faces the lower end surface of the stem 4 perpendicular to the axial direction. Therefore, the diaphragm retainer 6 always contacts the stem 4 at the highest part 6a, and a force is applied to the diaphragm retainer 6 along the central axis direction. Incidentally, if the upper end surface of the diaphragm retainer 6 is a flat surface and the lower end surface of the stem 4 is a curved surface with the center of the cylinder being the highest part, since there is a gap between the stem 4 and the bonnet 7, the contact position between the stem 4 and the diaphragm retainer 6 may deviate from the center of the diaphragm retainer 6. When the contact position between the stem 4 and the diaphragm 3 deviates from the center of the diaphragm retainer 6, the force is unevenly applied to the retainer adapter 5 and the diaphragm 3, which may cause a decrease in durability and the generation of particles. Therefore, it is desirable to provide a curved surface on the diaphragm retainer 6 side, and the diaphragm 3 is pressed in a deformed state, effectively suppressing the occurrence of sheet leakage due to single-sided contact with the sheet-shaped valve seat 22.

Industrial Applicability

[0024] The diaphragm valve according to the embodiment of the present invention can prevent the axial displacement of the diaphragm retainer and prevent the occurrence of sheet leakage and particles, so it can be suitably used for a flow control device for a semiconductor manufacturing apparatus.

Explanation of Reference Numerals

[0025] [[ID=!14]]1 Diaphragm valve 2 Valve body 20 Fluid flow path 21 Valve chamber 22 Valve seat 3 Diaphragm 4 Stem 5 Retainer adapter 6 Diaphragm retainer 60 Diaphragm retainer body 61 Cover 6a Highest part 7 Bonnet

Claims

1. A valve body having a valve chamber that forms a valve seat and a fluid passage that communicates with the valve chamber, A diaphragm that opens and closes the fluid passage by contacting and separating from the valve seat, A stem operated by an actuator, A cylindrical diaphragm retainer is positioned between the stem and the diaphragm, and moves in the central axis direction as the stem operates, deforming the diaphragm. A hollow bonnet is fixed to the valve body, and the stem and the diaphragm retainer are arranged inside it, An annular retaining adapter interposed between the bonnet and the valve body, which presses the peripheral edge of the diaphragm to fix the diaphragm to the valve body, A diaphragm valve having, The end face of the stem that contacts the diaphragm retainer is flat. The end face of the diaphragm retainer that contacts the stem is a curved surface whose highest point is at the center of the cylinder. The inner surface of the retaining adapter and the outer surface of the diaphragm retainer are in sliding contact. A diaphragm valve in which the inner surface of the bonnet and the outer surface of the diaphragm retainer do not come into contact.

2. The diaphragm retainer comprises a bottomed cylindrical lid with a curved surface whose side surface slides against the inner circumferential surface of the retaining adapter and whose one end surface abuts against the stem, and a diaphragm retaining body which is fitted into a recess on the other end surface of the lid, according to claim 1.

3. The diaphragm valve according to claim 1 or 2, wherein the material of the diaphragm retainer is Invar material.

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