JP4119109B2 - Piezoelectric element driven metal diaphragm type control valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a piezoelectric element-driven metal diaphragm type control valve used to control a flow rate of gas, etc., and is mainly used in a pressure type flow control device such as a semiconductor manufacturing facility or a chemical manufacturing facility. It is.
[0002]
[Prior art]
In recent years, pressure-type flow rate control devices are widely used in place of mass flow controllers in semiconductor manufacturing facilities and chemical manufacturing facilities.
This pressure type flow control device adjusts the pressure P ₁ by the control valve on the upstream side of the orifice while maintaining the upstream pressure P _{1 of the} orifice at about twice or more the downstream pressure P ₂ . The basic principle is that the flow rate Qc downstream of the orifice is calculated by Qc = KP ₁ (where K is a constant) and controlled to a predetermined set value, which is disclosed in JP-A-8-338546 and the like. Yes.
[0003]
By the way, the pressure type flow control device has high contact resistance, low dust generation, good gas replacement property, fast opening and closing speed, and quick and reliable closing of the fluid passage. So-called metal diaphragm type valves are often used from the viewpoint of being able to do so, and air cylinder driving devices, solenoid driving devices, and piezoelectric element driving devices are widely used as driving devices for control valves. Since the type of driving device can operate at a high speed and has less hysteresis phenomenon in operation characteristics, it is often used in a high-precision flow control valve.
[0004]
FIGS. 9 and 10 show an example of a control valve provided with a conventional piezoelectric element type driving device. FIG. 9 shows a normally open type control valve (JP-A-7-310842, etc.), and FIG. 10 shows a normally closed type. Each shows a mold control valve (Japanese Patent Laid-Open No. 8-338546).
9, 1 is a valve body, 2 is a metal diaphragm valve body, 3 is a diaphragm presser, 4 is a presser adapter, 5 is a guide body, 6 is a holding case, 7 is a bonnet nut, 8a and 8b are balls, 9 is a lower cradle, 10 is a piezoelectric element, 11 is an upper cradle, 12 is a positioning nut, 13 is a lock nut, 14 is a protective case, 15 is a connector, and 16 is a lead wire. As a result, the piezoelectric element 10 extends, and the control valve is closed by pressing the metal diaphragm valve element 2 toward the valve seat through the diaphragm retainer 3.
When the valve opening signal is turned off, the piezoelectric element 10 returns from the extended state to the original shortened state, and the diaphragm valve body 2 returns to the valve open state by the elastic force of the diaphragm itself.
[0005]
10 and 11, 17 is a base body fixed to the bonnet nut 7, 18 is a disc spring, 19 is a piezoelectric element support rod, 20 is a positioning bolt, 21 is an upper support frame, The element 10 is supported and fixed by a positioning bolt 20 or the like between the upper support frame 21 and the lower cradle 9 via three piezoelectric element support bars 19.
[0006]
That is, the upper end portion of each piezoelectric element support bar 19 is fixed to the upper support frame 21, and the lower end portion thereof is inserted into the lower support 9 fixed to the base body 17 and engaged with the diaphragm presser 3. ing. Further, the diaphragm presser 3 is always pressed downward by the disc spring 18, whereby the metal diaphragm valve body 2 is always in contact with the valve seat and is held in the closed state.
[0007]
When a valve opening signal is input to the control valve shown in FIG. 10, the piezoelectric element 10 expands, whereby the three piezoelectric element support rods 19 are pushed upward against the elastic force of the disc spring 18. As a result, the diaphragm retainer 3 engaged with the lower end of the piezoelectric element support rod 19 is pulled upward, and the diaphragm valve body 2 moves to the valve opening position by its elastic force. When the valve opening signal is turned off, the piezoelectric element 10 is shortened, and the diaphragm presser 3 is lowered by the elastic force of the disc spring 18, whereby the metal diaphragm valve body 2 comes into contact with the valve seat.
[0008]
The normally closed control valve shown in FIGS. 10 and 11 has a high operating speed as a so-called high-speed opening / closing type control valve.
However, many problems to be solved still remain in the normally closed type piezoelectric element drive type metal diaphragm type control valve, making the control valve easy and easy to assemble, reducing the number of parts, improving the response speed, Reduction of operational hysteresis (reduction in variation in flow control characteristics) remains a problem.
[0009]
That is, in the control valve of FIGS. 10 and 11, the extension of the piezoelectric element 10 is transmitted to the diaphragm presser 3 by the three piezoelectric element support bars 19. There is considerable difficulty in evenly transmitting the extension force to the diaphragm retainer 3, resulting in a hysteresis phenomenon in the flow rate control characteristics, and the piezoelectric element 10 transmitted to the diaphragm retainer 3 via the support rods 19. There is a problem that it is difficult to increase the operating speed of the valve due to a timing difference between the extension forces.
Further, there are problems that it takes time to assemble the support rod 19 and the piezoelectric element 10 and the like, and it is difficult to reduce the manufacturing cost of the control valve due to the large number of parts.
[0010]
Furthermore, the upper ball 8b and the lower ball 8a are provided, and the upward pulling force applied to the diaphragm presser 3 by the extension of the piezoelectric element 10 is exactly matched with the axis of the control valve, thereby stabilizing the operation of the diaphragm valve body 2. However, it is difficult to adjust the tightening amount between the support rod fixing nuts 22 for fixing the three support rods 19 to the upper support frame 21, and as a result, higher operation stability is achieved. There is a problem that it cannot be achieved.
[0011]
[Problems to be solved by the invention]
The present invention has the above-mentioned problems in the conventional normally closed type piezoelectric element driven metal diaphragm type control valve, that is, (1) it is difficult to achieve hysteresis in the operating characteristics of the valve or to further improve the operating speed. (2) It is difficult to reduce the manufacturing cost due to the large number of parts and assembly, and (3) it is difficult to further improve the stability of the operation. A normally closed type that enables significant reduction in manufacturing costs by reducing the number of parts and facilitating assembly, as well as stabilizing operation, reducing hysteresis, and achieving high-speed response. The piezoelectric element drive type metal diaphragm control valve is provided.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 includes a valve main body 1 provided with a fluid inlet / outlet, a hole 1a that forms a valve chamber, and a valve seat, and is disposed in the valve chamber so as to face the valve seat. The metal diaphragm valve body 2 that contacts the valve seat by pressing downward and is separated from the valve seat by elasticity when the pressing force is lost, and the outer peripheral edge of the metal diaphragm valve body 2 are airtight to the valve body 1. A presser adapter 4 to be pressed and a diaphragm presser 3 at the lower end are vertically inserted into the hole 1a with the lower end positioned above the diaphragm valve body and inward of the presser adapter 4. A cylindrical piezoelectric element supporting cylinder 23 having a worn bottom wall 23b, a disc spring 18 disposed on the bottom wall 23b of the piezoelectric element supporting cylinder 23, and a lower portion of the piezoelectric element supporting cylinder 23; Combining to the reduced diameter part from opposite sides A split base 26 formed of two split base pieces 26a having a short cylinder having an upper wall 26b and having a flange portion 26c for pressing the presser adapter 4 on the outer peripheral surface of the lower end, and the piezoelectric element supporting cylinder 23 is slidably inserted and is disposed above the split base 26 in the hole 1a, and is fixed to the valve body 1 by pressing the flange portion of the split base 26 downward with its tip. A cylindrical body fixing / guide body 24 for fixing the base 26 to the valve body 1, a lower cradle 9 disposed on the upper wall 26 b of the split base 26, located below the piezoelectric element support cylindrical body 23, and a piezoelectric element The piezoelectric element 10 inserted with the ball 8 a interposed on the lower cradle 9 in the element support cylinder 23, the bearing 28 disposed at the upper end of the piezoelectric element 10, and the piezoelectric element support cylinder 23 above Arranged in the piezoelectric element A positioning member for the positioning in the 0 of the piezoelectric element support cylinder 23 in which a basic structure of the invention.
[0013]
According to a second aspect of the present invention, in the first aspect of the present invention, the positioning member is a positioning cap nut 12 screwed onto the piezoelectric element supporting cylinder 23.
[0014]
According to a third aspect of the present invention, in the first aspect of the present invention, the ball 8 a interposed between the lower cradle 9 and the piezoelectric element 10 is integrally formed on the lower end surface of the piezoelectric element 10. It is a thing.
[0015]
According to a fourth aspect of the present invention, the split base 26 according to the first aspect of the present invention includes the insertion hole 26d for inserting a part of the outer peripheral wall of the piezoelectric element support cylinder 23 into the upper wall 26b, and the lower cradle 9. The fitting portion 26e for supporting and fixing is provided.
[0016]
A fifth aspect of the present invention is a method for fitting the split base 26 by removing the piezoelectric element supporting cylinder 23 in the first aspect of the invention in a symmetrical (direction) manner on both sides of the outer peripheral wall at the lower end thereof. The piezoelectric element supporting cylinder 23 is configured to have a hole 23a.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic longitudinal sectional view of a control valve showing a first embodiment of the present invention, and FIG. 2 is a side view of the control valve of FIG. 1 and 2, the same parts and members as those in FIGS. 9 to 11 are denoted by the same reference numerals.
[0018]
1 and 2, 1 is a valve body, 1a is a hole provided in the valve body, 2 is a metal diaphragm valve body, 3 is a diaphragm holder, 4 is a presser adapter, 8a is a ball, and 9 is a lower base. 10 is a piezoelectric element, 11 is an upper cradle, 12 is a positioning nut, 13 is a lock nut, 14 is a protective case, 15 is a connector, and 18 is a disc spring. And having substantially the same configuration.
Reference numeral 23 denotes a piezoelectric element supporting cylinder, 24 is a cylinder fixing / guide body, 25 is an O-ring, 26 is a split base, 27 is a mounting bolt, and 28 is a bearing. These members are used in the present invention. Newly adopted.
[0019]
In the embodiment shown in FIG. 1, a ball 8 a separately formed between the lower cradle 9 and the piezoelectric element 10 is inserted, but the tip is at the center of the lower end surface of the piezoelectric element 10. It is also possible to have a configuration in which spherical projections are formed integrally and are brought into contact with the lower cradle 9 as balls 8a.
[0020]
The valve body 1 is made of stainless steel and includes a hole 1a forming a part of the valve chamber, a fluid inlet, a fluid outlet, a fluid passage, a valve chamber, a valve seat, and the like. The metal diaphragm body 2 is formed of a thin plate of nickel chrome alloy steel, and is formed in an inverted dish shape with a central portion slightly bulging upward. The shape of the diaphragm valve body 2 may be a flat plate shape, and the material may be stainless steel, Inconel alloy or other alloy steel. Further, in the present embodiment, one diaphragm is used, but a diaphragm valve body in which two to three diaphragms are laminated can also be used.
[0021]
The metal diaphragm 2 is disposed in the valve chamber so as to face the valve seat, and a fixing bolt 27 is fastened to the valve body 1 through a presser adapter 4, a split base 26 and a cylinder fixing / guide body 24. Thus, the outer peripheral edge of the diaphragm 2 is airtightly held and fixed to the valve body 1 side. The presser adapter 4, the cylinder fixing / guide body 24, the split base 26 and the like are made of metal such as stainless steel.
[0022]
As shown in FIGS. 3 and 4, the support cylinder 23 of the piezoelectric element (piezo element) 10 is formed in a cylindrical shape with an invar material having a small coefficient of thermal expansion, and the upper portion has a large diameter for housing the piezoelectric element 10. The lower portion of the portion 23c is formed in a reduced diameter cylindrical shape 23d for accommodating the lower cradle 9 and the disc spring 18 and the like.
Further, the lowermost end portion of the support cylinder 23 is formed in a cavity 23e for fitting the diaphragm retainer 3, and the diaphragm retainer 3 is inserted and fixed therein as shown in FIG.
[0023]
3 and 4 are a longitudinal sectional view of the support cylinder 23 and a cross-sectional view as seen in FIG. 3, and in the vicinity of the boundary between the large diameter portion 23c and the reduced diameter portion 23d of the support cylinder 23, By removing both side portions over a certain length and depth, a hole portion 23a for inserting and combining the split base piece 26a from both sides in an opposing manner is formed. That is, from both sides of the hole 23a, half-divided split base pieces 26a forming a split base 26, which will be described later, are assembled so as to face each other, and are integrally held and fixed as the split base 26 by the cylindrical body fixing / guide body 24. Is done. Needless to say, the disc spring 18 is inserted into the bottom 23b of the reduced diameter portion 23d before the split base piece 26a is assembled as shown in FIG.
[0024]
5 and 6 are a plan view showing an assembled state of the split base 26 and a sectional view taken along the line E-I in FIG. As is clear from FIGS. 5 and 6, each split base piece 26a has a flange 26c formed on the outer periphery of the lower end of the short cylindrical body having the upper wall 26b, and an insertion hole 26d and a fitting portion on the upper wall 26b. What formed 26e is divided into two from the center, and the split base 26 is formed by assembling both split base pieces 26a in an opposing manner.
[0025]
That is, as shown in FIG. 1, the flange portion 26 c receives a pressing force from the lower end of the cylindrical body fixing / guide body 24 and presses the presser adapter 4, and the insertion hole 26 d has a support cylindrical body 23. Further, the fitting portion 26e is positioned between the lower cradle 9 and the wall of the support cylinder 23 to position the three members 9, 23, and 26. It has the action to do.
[0026]
The bearing 28 is formed of a bearing receiver 28a and a small ball 28b, and is disposed above the upper receiving tray 11 to facilitate the rotation of the positioning cap nut 12.
[0027]
Since the control valve according to the embodiment of FIG. 1 is mainly used as a control valve for the pressure type flow control device, as shown in FIG. 1, the valve body 1 has an orifice guide 30a, a gasket 30b, an orifice 30c. Or the like, a pressure sensor 31a, a gasket 31b, a connector 31c, a pressure flange 31d, a pressure bolt 31e, etc., and a primary connection 29 comprising a connection guide 29a, a gasket 29b, etc. Etc. are provided. Reference numeral 32 denotes a control circuit mounting plate such as a piezoelectric element provided in the protective case 14.
[0028]
The assembly of the control valve is substantially the same as in the case of the normally open control valve shown in FIG. 9, and a piezoelectric device in which the metal diaphragm valve body 2, the presser adapter 4, and the diaphragm presser 3 are fixed in the hole 1a of the valve body 1. The element support cylinder 23, the disc spring 18, the split base 26, and the lower cradle 9 are assembled in this order, and the support cylinder 23 is inserted into the valve body 1 via the cylinder fixing / guide body 24.
Next, the ball 8 a, the piezoelectric element 10, the upper cradle 11, and the bearing 28 are inserted into the support cylinder 23 in this order, and the piezoelectric element is adjusted by adjusting the tightening amount of the positioning bag nut that forms the positioning member 12. The operating stroke of the metal diaphragm valve body 2 by 10 is finely adjusted to the set value.
[0029]
By fixing the cylinder body and tightening the guide body 24, the split base 26, the support cylinder body 23, the lower receiving base 9, the disc spring 18, the diaphragm retainer 3, the diaphragm valve body 2 and the like are all in a predetermined position as described above. In addition to being fixed automatically in an orderly manner, the shafts of the ball 8a, the piezoelectric element 10, the support cylinder 23, and the like are matched with extremely high precision by tightening the positioning member 12.
[0030]
Referring to FIG. 1, when a valve opening signal is input from a control circuit (not shown) via a connector 15 (input voltage 0 to 120 v), the piezoelectric element 10 expands by a set value (between 0 and 45 μm). To do.
As a result, a push-up force of about 40 to 80 kg acts on the support cylinder 23, and the support cylinder 23 is made elastic by the disc spring 18 in a state where the shaft core is held by the O-ring 25 of the cylinder fixing / guide body 24. On the contrary, it increases by the set value. As a result, the diaphragm valve body 2 is separated from the valve seat by the elastic force and is opened.
Conversely, when the valve opening input is turned off, the piezoelectric element 10 returns to the original length, and as a result, the bottom of the piezoelectric element support cylinder 23 is pushed downward by the elastic force of the disc spring 18. The diaphragm presser 3 causes the metal diaphragm valve element 2 to contact the valve seat and close the valve.
When the valve opening stroke is 45 μm and the valve seat has a diameter of 1 mmφ, the required operation time from full closing to full opening of the valve is about 30 msec or less.
[0031]
FIG. 7 shows a second embodiment of the present invention, in which an orifice downstream pressure sensor having substantially the same structure as the pressure sensor attachment portion 31 of FIG. 1 is attached to the downstream side of the orifice attachment portion 30 of the valve body 1. A portion 33 is provided.
Since the configuration of the control valve itself is the same as that in FIG. 1, its description is omitted here.
[0032]
FIG. 8 shows a third embodiment of the present invention. In the control valve of FIG. 1, a temperature detection sensor (thermistor) 34 is disposed in the vicinity of the pressure sensor mounting portion 31, thereby the pressure sensor 31a. Temperature detection for temperature compensation is performed. The configuration of the control valve itself is exactly the same as in FIG.
[0033]
【The invention's effect】
In the present invention, a normally closed type piezoelectric element driven metal diaphragm type control is formed by organically combining the piezoelectric element supporting cylinder 23, the cylinder fixing / guide body 24, the split base 26 and the disc spring 18. Since the valve is configured, the number of parts can be significantly reduced as compared with a conventional control valve of this type, and the manufacturing cost can be reduced.
In addition, when assembling parts, the axes of each member can be automatically aligned, resulting in a significant improvement in assembly accuracy and reduced variations in valve control characteristics and hysteresis due to variations in assembly accuracy. In addition, it is possible to improve operational stability and responsiveness.
The present invention has excellent practical utility as described above.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a normally closed piezoelectric element drive type metal diaphragm type control valve according to a first embodiment of the present invention.
FIG. 2 is a side view of the control valve of FIG.
FIG. 3 is a longitudinal sectional view of a piezoelectric element supporting cylinder.
4 is a cross-sectional view taken along the line E-I in FIG. 3;
5 is a plan view of the split base 26. FIG.
6 is a cross-sectional view taken along the line E-I in FIG. 5;
FIG. 7 is a front view of a control valve according to a second embodiment of the present invention.
FIG. 8 is a side view in which a part of a control valve according to a third embodiment of the present invention is broken.
FIG. 9 is a schematic vertical sectional view of a conventional normal open type piezoelectric element drive type metal diaphragm type control valve.
FIG. 10 is a schematic vertical cross-sectional view of a conventional normally closed type piezoelectric element driven metal diaphragm type control valve.
11 is a cross-sectional view taken along the line E-I in FIG. 10;
[Explanation of symbols]
1 is a valve body, 1a is a hole, 2 is a metal diaphragm valve body, 3 is a diaphragm retainer, 4 is a presser adapter, 8a is a ball, 9 is a lower base, 10 is a piezoelectric element, (piezo element), and 11 is an upper part A cradle, 12 is a positioning member (positioning cap nut), 13 is a lock nut, 14 is a protective case, 15 is a connector, 18 is a disc spring, 23 is a piezoelectric element support cylinder, 23a is a hole, 23b is a bottom wall , 24 is a cylinder fixing / guide body, 25 is an O-ring, 26 is a split base, 26a is a split base piece, 26b is an upper wall, 26c is a flange, 26d is an insertion hole, and 26e is a fitting portion. , 27 is a fixing bolt, 28 is a bearing, 28a is a bearing receiver, 28b is a small ball, 29 is a primary connection part, 29a is a connection guide, 29b is a gasket, 30 is an orifice mounting part, 30a is an orifice guide, 0b is a gasket, 30c is an orifice, 31 is a pressure sensor mounting portion, 31a is a pressure sensor, 31b is a gasket, 31c is a connector, 31d is a holding flange, 31e is a fixing bolt, 32 is a control circuit mounting plate, and 33 is downstream of the orifice. Side pressure sensor mounting part 34 is a temperature detection sensor.

Claims (5)

A valve body 1 provided with a hole portion 1a that forms a fluid inlet / outlet and a valve chamber and a valve seat, and is disposed in the valve chamber so as to face the valve seat. A metal diaphragm valve body 2 that is sometimes separated from the valve seat by elasticity, a presser adapter 4 that presses the outer peripheral edge of the metal diaphragm valve body 2 to the valve body 1 in an airtight manner, and a diaphragm presser 3 at the lower end are provided. A cylindrical piezoelectric element support cylinder 23 having a bottom wall 23b vertically inserted into the hole 1a with the lower end positioned above the diaphragm valve body and inward of the presser adapter 4; The upper wall is obtained by combining the disc spring 18 disposed on the bottom wall 23b of the piezoelectric element support cylinder 23 and the reduced diameter portion of the lower portion of the piezoelectric element support cylinder 23 in an opposing manner from both sides thereof. Forming the short cylinder with 26b and the lower end A split base 26 composed of two split base pieces 26a provided with a flange portion 26c for pressing the presser adapter 4 on the peripheral surface and the piezoelectric element support cylinder 23 are slidably inserted, and the hole 1a is inserted into the hole 1a. A cylindrical body fixing / guide body which is disposed above the split base 26 and fixes the split base 26 to the valve body 1 by pressing the flange portion of the split base 26 downward at the distal end by fixing to the valve body 1. 24, a lower pedestal 9 located on the upper wall 26b of the split base 26 and positioned below the piezoelectric element support cylinder 23, and a ball onto the lower cradle 9 in the piezoelectric element support cylinder 23 The piezoelectric element 10 inserted through 8a, the bearing 28 disposed at the upper end of the piezoelectric element 10, and the piezoelectric element support cylinder 23 are disposed above the piezoelectric element support cylinder 23. Positioning to adjust the position inside Normally closed type piezoelectric element driven metal diaphragm control valve characterized by being configured from a wood. The piezoelectric element drive type metal diaphragm type control valve according to claim 1, wherein the positioning member is a positioning cap nut 12 screwed onto the piezoelectric element support cylinder 23. 2. A piezoelectric element-driven metal diaphragm according to claim 1, wherein a ball 8a interposed between the lower cradle 9 and the piezoelectric element 10 is formed integrally with the lower end surface of the piezoelectric element 10 to form a ball 8a. Mold control valve. The split base 26 is configured to include an insertion hole 26d for inserting a part of the outer peripheral wall of the piezoelectric element support cylinder 23 into an upper wall 26b, and a fitting portion 26e for supporting and fixing the lower cradle 9. 2. A piezoelectric element drive type metal diaphragm type control valve according to 1. The piezoelectric element support cylinder 23 is configured to have a hole 23a for fitting the split base 26 by deleting the both sides of the outer peripheral wall of the lower end portion symmetrically (direction). The piezoelectric element drive type metal diaphragm type control valve according to claim 1.

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