Valve actuator and valve using same

Abstract

To provide an actuator for a valve having a stroke increase mechanism which can increase a moving stroke of a valve body.SOLUTION: In an actuator for a valve for use in the valve having a valve body for allowing and blocking the circulation of fluid while abutting on, and separating from a valve seat, and having a stroke increase mechanism for increasing a stroke of the valve body, the stroke increase mechanism has: a plurality of balls arranged between an output end of the actuator and the valve body, and pressed by the abutment of the output end; a ball holding member in which a ball accommodation space for accommodating the balls is formed at an output end side, and the ball accommodation space is connected to the valve body having a conical support tapered face which is spread upward outwardly; a valve body pressing part for pressing the valve body at one end of the valve body side being a stem penetrating an insertion hole which is formed at a center part of the ball holding member; and a stem tapered face which is tapered at a tip abutting on the balls at the other end of the output end side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a valve actuator equipped with a stroke increasing mechanism that increases the stroke of a valve element of a valve that opens and closes the flow of a fluid, and a valve using the same. [Background technology]

[0002] In semiconductor manufacturing equipment and chemical plants, various types of valves are used to control the flow rate of material gases, etching gases, etc. In some cases, it is necessary to control the opening and closing of a valve in a short period of time, such as on the order of milliseconds, and in such cases, this is achieved by opening and closing the valve using a piezoelectric element, etc.

[0003] The valve described in Patent Document 1 adjusts the force that the output end of the piezoelectric element applies to the lower support by expanding and contracting the piezoelectric element, causing the diaphragm and valve seat to come into contact with and separate from each other, thereby opening and closing the flow of fluid. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. WO2019 / 159959 [Patent Document 2] International Publication No. WO2018 / 123852 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to increase the flow rate of a valve, it is necessary to increase the Cv value, which in turn requires a larger stroke of the valve disc. Although it is possible to increase the Cv value with air-driven or motor-driven valves, when short-period opening and closing on the order of milliseconds is required, it is common to use a valve equipped with a piezoelectric actuator.

[0006] However, depending on whether short-term responsiveness or fluid flow rate is more important, piezoelectric element drive, air drive, or motor drive are used alternatively depending on the situation in which the valve is used, and it is difficult to realize a valve actuator that satisfies both responsiveness and Cv value.

[0007] Semiconductor manufacturing equipment and chemical plants require valves that can control the flow of fluid gases at high speed and adjust various changing flow rates, and it is becoming increasingly difficult to meet these demands by simply choosing between responsiveness and Cv value, as has been the case up until now.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a valve actuator equipped with a stroke increasing mechanism capable of increasing the movement stroke of the valve disc. [Means for solving the problem]

[0009] The actuator for a valve with a stroke increasing mechanism according to the present invention (1), which has been made to solve the above problems, is used in a valve having a valve body formed in a valve body and a valve seat arranged in a fluid flow path to open and close the flow of fluid by abutting and separating from the valve seat, and is an actuator for a valve having a stroke increasing mechanism for increasing the stroke of the valve body, the stroke increasing mechanism being arranged between an output end of the actuator and the valve body, the stroke increasing mechanism comprising a plurality of balls against which the output end abuts and is pressed, and a ball accommodating space for accommodating the balls being provided on the output end side, the ball accommodating space comprising a ball retaining member connected to the valve body having a conical support tapered surface that widens outward and upward, and a stem penetrating a through hole formed in the center of the ball retaining member, the stem having a valve body pressing portion at one end on the valve body side for pressing the valve body, and a stem tapered surface at the other end on the output end side with a tapered tip that abuts against the balls.

[0010] By utilizing such a stroke increasing mechanism, even if the stroke of the actuator that moves the valve body is small, it is possible to increase the small stroke by several times, thereby increasing the Cv value.

[0011] The present invention (2) is an actuator for a valve according to the present invention (1), wherein the output end is moved by expansion and contraction of a piezoelectric element, and the valve body holding portion is moved by the movement of the output end.

[0012] Piezoelectric actuators have the disadvantage of good time response but a small stroke, so by providing this type of stroke increasing mechanism, even a piezoelectric actuator can have good time response and the stroke of the valve disc can be increased, thereby increasing the Cv value of the valve.

[0013] The present invention (3) is the actuator for a valve according to either the present invention (1) or the present invention (2), wherein the valve element is a diaphragm.

[0014] Flow control devices are used in film forming devices and etching devices for semiconductor manufacturing. Metal diaphragm valves are widely used in flow control devices because of their high corrosion resistance, low dust generation, good gas replacement, good responsiveness, and the ability to quickly and reliably close the fluid passage when the valve is closed. In addition, piezoelectric element drive devices (piezo actuators) are widely used as drive mechanisms for opening and closing metal diaphragms, and are often used in flow control valves that require high accuracy because they can operate at high speed and have relatively small hysteresis in their operating characteristics. Piezoelectric element drive actuators have the disadvantage that the stroke of the valve body presser that presses the valve body (diaphragm) is small, but even valves that use such piezoelectric element drive actuators can also have a large Cv value because they are equipped with a stroke increase mechanism.

[0015] The present invention (4) is a valve equipped with the valve actuator according to any one of the present inventions (1) to (3). By using such a valve, it is possible to obtain a valve with good time response and a high Cv value. Effect of the Invention

[0016] According to the present invention, it is possible to provide an actuator for a valve that can increase the stroke of the valve element. [Brief description of the drawings]

[0017] [Figure 1] 1 shows a diaphragm valve equipped with a valve actuator according to an embodiment of the present invention, (A) showing the closed state and (B) showing the open state. [Diagram 2] 5A to 5C are schematic diagrams illustrating the operation of a stroke increasing mechanism of the valve actuator according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or its uses.

[0019] 1 shows a diaphragm valve equipped with a valve actuator according to an embodiment of the present invention, with (A) showing the closed state and (B) showing the open state. An inlet flow path 11 and an outlet flow path 12 are formed inside a valve body 10 of the valve 1, and a valve seat 13 is disposed at the internal open end of the inlet flow path 11. A valve element (diaphragm) 14 that opens and closes the flow of fluid by coming into and out of contact with the valve seat 13 is fixed to the valve body 10 by a presser adapter 15. In this embodiment, a diaphragm is used as this valve element 14, but it may also be, for example, an inverted cone-shaped needle-shaped element formed at the tip of a stem 20.

[0020] The upper part of the valve body 10 protrudes upward, and a recess for accommodating the diaphragm 14 and the press adapter 15 is formed inside the recess, and a female thread is cut on the inside of the recess. A ball retaining member 30, which functions as a bonnet and has a male thread that screws into the female thread, is fixed to the valve body 10 by screwing. The diaphragm 14 is formed, for example, from a thin plate of nickel-chromium alloy steel, and is formed into an inverted dish shape with the center part slightly bulging upward. The shape of the diaphragm 14 may be flat, and the material may be stainless steel, Inconel alloy, or other alloy steel. The diaphragm 14 may be formed from one diaphragm, or may be formed by stacking two or three diaphragms.

[0021] A through hole 31 through which the stem 20 passes is formed in the center of the ball retaining member 30. A valve body pressing portion 21 that presses the diaphragm 14 is formed at the lower end of the stem 20, and a stem tapered surface 22 is formed at the upper end. The upper part of the ball retaining member 30 protrudes upward and is internally provided with a female thread that screws into the guide member 48, and the outer surface of the lower end of the guide member 48 is provided with a male thread for screwing into the guide member 48.

[0022] A recess is provided in the upper part of the ball holding member 30, into which the guide member 48 is screwed. A further recess is formed below this recess to become the ball accommodating space 33, and the bottom surface of this ball accommodating space 33 forms a conical support tapered surface 32 that widens outward and upward.

[0023] A through hole is provided in the guide member 48 in the vertical direction, and a support cylinder 41 is disposed through the through hole and containing a piezoelectric element 40 therein. The support cylinder 41 has a large diameter portion at the top and a small diameter portion at the bottom, each of which has a recess. The large diameter portion recess is provided with a piezoelectric element 40, and the small diameter portion recess is abutted against a lower support 42 that is pressed downward by the piezoelectric element 40, and a split base 43 is disposed below the large diameter portion. The split base 43 is formed by assembling two half-split base pieces facing each other, and the guide member 48, the split base 43, and the ball holding member 30 are integrally held and fixed by the guide member 48. Before assembling the split base 43, an elastic member 44 is inserted into the recess inside the small diameter portion. The piezoelectric element 40 can be a metal-sealed laminated piezoelectric actuator in which a piezo stack in which piezoelectric elements are laminated is sealed in a metal container.

[0024] The lower part of the lower narrow diameter part of the support cylinder 41 forms the output end 45 of the valve actuator 2, and the bottom surface of this output end 45 is the output end lower surface 46. The output end lower surface 46 abuts against the upper surface of the ball 34, and the ball 34 also contacts the support tapered surface 32 and the stem tapered surface 34. When the number of balls to be arranged is three, they are arranged at 120 degree intervals, and when the number of balls is four, they are arranged at 90 degree intervals. If the number of balls is too large, the actuator will become large, so when making a compact actuator, the number of balls is preferably three to four.

[0025] A lock nut 51 and a cap nut 50 are disposed on the upper part of the supporting cylinder 41 for positioning and fixing the piezoelectric element 40 inside the supporting cylinder 41. Wiring 52 for applying voltage to the piezoelectric element 40 extends from the upper side of the cap nut 50.

[0026] In FIG. 1(A), the positioning of the piezoelectric element 40 is performed so that the valve body pressing portion 21 presses the diaphragm 14 to close the valve 1. When a voltage is applied to the piezoelectric element 40 from this state through the wiring 52, the piezoelectric element 40 expands slightly. When the piezoelectric element 40 expands, a downward pressing force acts on the lower support 42, but the lower support 42 is in contact with the center of the split base 43 and the position does not change. Therefore, a pushing force corresponding to the expansion of the piezoelectric element 40 acts on the support cylinder 41, and the support cylinder 41 rises against the elastic force of the elastic member 44 while the axis is held by the guide member 48. As a result, the pressing force from the valve body pressing portion 21 to the diaphragm 14 decreases, and the diaphragm 14 is lifted off the valve seat 13 by its own elastic force, and the valve is opened. As the elastic member 44, for example, a stack of disc springs can be used.

[0027] FIG. 1(B) shows the state in which the piezoelectric element 40 is expanded by applying a voltage from the wiring 52 to the piezoelectric element 40. The expansion of the piezoelectric element 40 causes the support cylinder 41 to move upward by L1. As the support cylinder 41 moves upward, the output end lower surface 46 also moves upward by L1, the stem 20 moves upward, and the ball 34 moves laterally outward, and stops when the support cylinder 41, the ball 34, and the stem 20 are balanced. FIG. 1(B) shows the state after stopping. The stem 20 moves upward by L2, so the valve body holding part 21 also moves upward by L2, and the diaphragm 14 can also deform upward by L2. Since L2 is greater than L1, the stroke is enlarged. The amount of increase in the stroke is determined by the angle of the tapered surface 32 and the stem tapered surface 22. When the divergence angle of the tapered surface 32 is 110° and the angle of the tip of the stem tapered surface 22 is 30°, L2 can be increased to about 8 times L1, or about 10 times depending on the angle.

[0028] FIG. 2 shows a schematic diagram of the mechanism by which the stroke is enlarged. The output end lower surface 46 when the valve is closed is shown by a horizontal dotted line. When the valve changes from the closed state to the open state, the output end lower surface 46' is shown by a solid line drawn above the dotted line of the output end lower surface 46. The vertical distance between these two straight lines is L1. The support taper surface 34 is fixed to the valve body 10 and does not move. The ball 34 when the valve is closed is shown by a dotted circle. When the output end lower surface 46 moves upward by L1, the ball 34 becomes the solid circle of the ball 34', and the ball 34 moves laterally outward. The stem taper surface 22 (dotted line) moves to the stem taper surface 22' (solid line), and the upward movement distance is L2.

[0029] It is clear that L2 is larger than L1, and the stroke is enlarged. As is clear from Figure 2, the principle of the stroke enlargement mechanism is based on a structure in which the ball 34 is disposed surrounded by the output end lower end surface 46, the support tapered surface 32, and the stem tapered surface 22, and the ball 34 is supported at three points. In the embodiment shown in Figure 2, when L1 is 58 μm, L2 is 478 μm, which is about eight times that.

[0030] In Fig. 2, the stem taper surface 22' (solid line) abuts against the output end lower surface 46' (solid line), but in Fig. 1, a recess is provided in the center of the output end lower surface 46, so there is no abutment. This recess is omitted in Fig. 2. [Industrial Applicability]

[0031] As described above, the valve actuator of the present invention can increase the stroke even in cases where the stroke is small, such as in cases where the actuator is driven by a piezoelectric element, and therefore can be suitably applied to valves. [Explanation of symbols]

[0032] 1 Valve 2 Valve Actuator 10 Valve body 11 Inlet channel 12 Outlet flow path 13 Valve seat 14 Valve body (diaphragm) 15 Presser adapter 20 Stem 21 Valve body holder 22, 22' Stem tapered surface 30 Ball holding member 31 Through hole 32 Support tapered surface 33 Ball storage space 34, 34' Ball 40 Piezoelectric element 41 Support cylinder 42 Lower support 43 Divided basis 44 Elastic member 45 Output terminal 46, 46' Output end bottom surface 48 Guide member 50 Cap nut 51 Lock nut 52 Wiring

Claims

1. 1. A valve actuator for use in a valve having a valve body that opens and closes a flow of a fluid by coming into contact with and separating from a valve seat disposed in a fluid flow path formed in a valve body, the valve actuator comprising: a stroke increasing mechanism that increases the stroke of the valve body, the stroke increasing mechanism is disposed between the output end of the actuator and the valve body, A plurality of balls that are pressed against the output end by contacting the balls; a ball accommodating space for accommodating the ball is provided on the output end side, and the ball accommodating space is connected to the valve body having a conical support tapered surface that widens outward and upward; a stem that passes through a through hole formed in the center of the ball retaining member, the stem having a valve body pressing portion at one end on the valve body side that presses the valve body, and a stem tapered surface having a tapered tip that abuts against the ball at the other end on the output end side; The valve actuator, wherein the valve body is a diaphragm that moves away from the valve seat by its own elastic force.

2. 2. The valve actuator according to claim 1, wherein the output end is moved by expansion and contraction of a piezoelectric element, and the valve disc holder is moved by the movement of the output end.

3. A valve comprising the valve actuator according to any one of claims 1 to 2.

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