Actuator Thrust Amplifier

Abstract

To provide a thrust amplification device of an actuator capable of fluctuating a speed at the time when an actuator starts operating, and a speed right before a valve body is seated on a valve seat.SOLUTION: A driving mechanism of an actuator 2 is composed of, for example, pushing means 33, a tip on a valve body 6 side extended from a piston 3 moved by compressed fluid, an upper surface of a disc 13, a taper surface 11a of a ball holder 11, and a plurality of balls 10 that are held in contact with an inclined surface 12 formed at the tip of a stem 32 and arranged so as to move outward as the stem 32 moves downward. The taper surface 11a of the ball holder 11 that is in contact with the ball 10, has a plurality of different taper angles.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a thrust amplifier for an actuator that operates a valve element of a valve that controls the flow of a fluid, and in particular to a thrust amplifier for an actuator that has a thrust amplification mechanism and can vary the moving speed of the valve element depending on the position of the valve opening. [Background technology]

[0002] Generally, valves that open and close a fluid flow path use an actuator to operate a valve element that moves toward and away from a valve seat. Metal diaphragm valves used in semiconductor manufacturing equipment, etc., generally have a metal diaphragm and a metal or resin annular valve seat, with an actuator mounted on the upper side of the diaphragm. This actuator has a stem that directly presses a diaphragm pressing body disposed above the diaphragm to move it up and down, and this stem presses or releases the diaphragm toward the valve seat via the diaphragm pressing body, thereby opening and closing the flow path between the diaphragm and the valve seat.

[0003] In semiconductor manufacturing, high-pressure fluids are sometimes passed through diaphragm valves, etc. In such cases, it is necessary to increase the thrust force when the actuator presses the diaphragm to resist the pressure of the high-pressure fluid. Actuators for such high-pressure valves often use a piston-cylinder structure, but the higher the pressure of the fluid being passed, the greater the thrust required, necessitating the use of larger pistons and cylinders. Furthermore, it is necessary to use multiple piston-cylinder structures. However, this structure results in a larger actuator.

[0004] To solve these problems, the invention described in Patent Document 1 has a ball, a stem with a tapered tip that contacts the side of the ball, a cylindrical member with a tapered contact surface above the ball, and a pressing member that presses the diaphragm presser that contacts the bottom of the ball, with the tip of the stem acting as a wedge to press the ball against the tapered surface of the cylindrical member.As a result, the ball moves a distance shorter than the movement distance of the stem, but with increased thrust, it presses the pressing member toward the diaphragm presser, thereby increasing the force pressing the diaphragm, thereby configuring a pressure boosting mechanism.

[0005] Figure 6 shows a valve using an actuator incorporating a conventional actuator thrust amplifier. This actuator 101 has a ball 102, a small-diameter needle 104 with a roughly conical inclined surface 103, a cylindrical member 106 with a cone-shaped inclined surface 105, and a pressing member 108 that presses a diaphragm retainer 107. This actuator 101 is of a so-called normally closed (NC) type, which normally maintains a diaphragm 112 in a diaphragm valve 111 in a closed state by the elastic force of a spring 110 provided inside a body 109. When compressed air (also called a driving fluid or working fluid) flows into the body 109 of the actuator 101, a piston 113 provided inside the body 109 rises, and the needle 104 rises along with the piston 113. As needle 104 rises, ball 102 moves in the radial direction along inclined surface 103 on the outer periphery of the needle, and then ball 102 also moves upward as guided by inclined surface 105 of cylindrical member 106, releasing the pressure from pressing member 108. The restoring force of diaphragm valve element 112 causes diaphragm retainer 107 to rise, opening the valve. At this time, the stroke (not shown) of needle 104 moving up and down is approximately five to six times the stroke of pressing member 108 moving up and down. When the inflow of compressed air is stopped from this open valve state, needle 104 is again seated on the valve seat due to the resilient force of spring 110. In other words, while the Cv value fluctuates, the needle moves at a constant speed due to the balance between the resilient force of spring 110 and the compressed air.

[0006] In addition, in a so-called normally open (NO) type, the spring 110 presses the piston 113 in a direction that moves the diaphragm valve element 112 away from the valve seat, and the compressed air acts on the piston 113 in a direction that moves the diaphragm valve element 112 toward the valve seat. Even in a normally open (NO) type, the speed of the diaphragm valve element 112 just before it seats on the valve seat is constant due to the pressure of the working fluid.

[0007] An actuator incorporating this thrust amplifier can be used not only for diaphragm valves, but also for valves with needle-shaped valve bodies and various other actuators that operate valve bodies. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 8-6828 Summary of the Invention [Problem to be solved by the invention]

[0009] In normal air-driven actuators, the movement of the piston is constant, and the operating speed is often fast in order to open and close the valve quickly. When operating from an open valve state, there are cases where it is desired to have the speed at which the valve disc seats on the valve seat slower than at the start of operation, or conversely, to have the speed faster just before seating. This has been an issue with conventional thrust amplifiers.

[0010] The present invention has been made in consideration of the above points, and has an object to provide a thrust amplifier for an actuator that can vary the speed when the actuator starts to operate and the speed immediately before the valve disc seats on the valve seat. [Means for solving the problem]

[0011] In order to solve the above problems, the thrust amplifier of the actuator according to the present invention comprises: a disk provided between an output end of an actuator that operates a valve body that opens and closes a fluid flow path and the valve body, the disk transmitting a thrust that presses the valve body; a ball presser disposed above the disk and having a conical tapered surface that widens outward and downward; a stem that passes through a through hole formed in the center of the ball retainer, extends from the drive mechanism of the actuator, and has a tapered inclined surface at its tip on the valve body side; a plurality of balls that are sandwiched between the upper surface of the disk, the tapered surface of the ball retainer, and the inclined surface of the stem and are arranged to move outward as the stem moves downward; The tapered surface of the ball retainer that comes into contact with the ball is formed with a plurality of different tapered angles.

[0012] The taper angle may be a tangent angle of a curved surface that is gentler on the outer diameter side than on the center side or that is convex outward.

[0013] The taper angle may be a tangent angle of a curved surface that is steeper on the outer diameter side than on the center side or that is convex inward.

[0014] The thrust amplifier of the actuator of the present invention can vary the speed when the actuator starts operating and the speed immediately before the valve disc seats on the valve seat by varying the taper angle of the tapered surface that contacts the ball. By making the taper angle gentler from the center to the outer diameter side, the speed immediately before the valve disc seats can be slowed. By making the taper angle a convex curved surface on the outward side, the taper angle is the tangent angle passing through the contact point with the ball, and the taper angle can be gradually gentler. Furthermore, by making the angle steeper from the center to the outer diameter side, the speed immediately before the valve disc seats can be increased. Similarly, by making the taper angle a convex curved surface on the inward side, the taper angle is the tangent angle passing through the contact point with the ball, and the taper angle can be gradually steeper.

[0015] In these cases, the inclination angle of the inclined surface of the stem can be formed at a plurality of different angles, which, together with the variation of the tapered surface angle of the ball retainer, allows for a plurality of speed variations. [Effects of the Invention]

[0016] According to the actuator of the present invention, it is possible to provide an actuator that can vary the speed when the actuator starts to operate and the speed immediately before the valve disc seats on the valve seat. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a partially cutaway front cross-sectional view showing a valve in a fully closed state using an actuator incorporating a thrust amplifier of the actuator of the present invention. [Figure 2] FIG. 10 is a partially cutaway front cross-sectional view showing a valve in a fully open state using an actuator incorporating a thrust amplifier of the actuator. [Figure 3] This is an enlarged partial view explaining the thrust amplifier of the actuator, where (a) shows the fully open state and (b) shows the fully closed state. [Figure 4] 10A and 10B are partially enlarged views for explaining a thrust amplifier of an actuator of a second embodiment, in which (a) shows a fully open state and (b) shows a fully closed state. [Figure 5] 1A and 1B are perspective cross-sectional views showing examples of a ball retainer of a thrust amplifier of an actuator of the present invention, where (a1) shows a first embodiment, (b1) shows a second embodiment, and (a2) and (b2) show modified examples. [Figure 6] FIG. 1 is a partially cutaway front cross-sectional view showing a fully closed state of a valve using an actuator incorporating a thrust amplifier of a conventional actuator. DETAILED DESCRIPTION OF THE INVENTION

[0018] A preferred embodiment of a thrust amplifier for an actuator according to the present invention will now be described with reference to the drawings. The shapes of the components and their relative positions described in these embodiments are merely illustrative examples and are not intended to limit the scope of the present invention unless otherwise specified. Furthermore, for convenience, the directions of components may be referred to as up, down, left, and right depending on the directions in the drawings, but these do not limit the scope of the present invention.

[0019] <Embodiment 1> 1 to 3 show a first embodiment of the present invention. Fig. 1 is a partially cutaway front cross-sectional view showing a valve V in a fully closed state to which an actuator 2 equipped with a thrust amplifier 1 of the actuator of the present invention is attached. The thrust amplifier 1 of the actuator of the present invention (hereinafter simply referred to as thrust amplifier 1) is provided between a stem 32, which is the output end of the actuator 2 that operates a valve element 6 made of, for example, a diaphragm, and the valve element 6, which cuts off communication between an inflow passage 71 and an outflow passage 72 through which a fluid flows. Specifically, it comprises a disk 13 that transmits the thrust that presses the valve body 6, a ball retainer 11 that is arranged above the disk 13 and has a conical tapered surface 11a that widens outward and downward, and a plurality of balls 10 that pass through a through hole 11b formed in the center of the ball retainer 11 and extend from the drive mechanism of the actuator 2, for example, the piston 3 that is moved by the pressing means 33 and driving fluid, and are held in contact with and sandwiched between the tip on the valve body 6 side, the upper surface of the disk 13, the tapered surface 11a of the ball retainer 11, and the inclined surface 12 formed at the tip of the stem 32, and are arranged so as to move outward as the stem 32 moves downward.

[0020] In the thrust amplifier 1 of the present invention, the tapered surface 11a of the ball retainer 11 that comes into contact with the ball 10 is formed with a plurality of different tapered angles. There are no particular limitations on the tapered angle as long as there are a plurality of tapered angles, but in this embodiment, the tapered surface 11a is configured with two different angles.

[0021] [valve] Valve V, which uses actuator 2 incorporating thrust amplifier 1 of the present invention, is composed of a valve body 7 having inlet flow path 71 and outlet flow path 72 through which fluid flows, and a valve seat 70 arranged around the periphery of the internal opening end of inlet flow path 71; a metal diaphragm 6 that abuts and separates from valve seat 70; a cylindrical diaphragm fixing member 4 that abuts against the periphery of diaphragm 6 and holds diaphragm 6 between it and the periphery of the recess in the valve body 7, and has a diaphragm holder 14 arranged inside; a bonnet 5 that screws into a male thread formed on the outer periphery of the recess in the valve body 7 and fixes diaphragm fixing member 4 to the valve body 7; and an actuator 2 attached to the bonnet 5.

[0022] Bonnet 5 is a cylindrical body with a step on its inner circumferential surface, and above the part that screws into valve body 7, disk 13, ball 10, and ball retainer 11 of thrust amplifier 1 are disposed, with the lower end face of disk 13 abutting against the upper end face of diaphragm retainer 14. Ball retainer 11 is fixed to bonnet 5 by, for example, screwing into bonnet 5, a cover member 15 that is concentric with and has approximately the same diameter as through-hole 11b of ball retainer 11.

[0023] [Actuator] The actuator 2 is composed of a hollow actuator body 20 fixed to the bonnet 5, a piston 3 which has a piston body 30 which is in sliding contact with a cylinder portion 20a formed on the upper inner peripheral surface of the actuator body 20, a flow path 31 which introduces a working fluid which acts on the piston body 30 into the interior, and a stem 32 which extends concentrically with the piston body 30, a pressing means 33 which applies thrust to the piston body 30, and an actuator cap 21 which is fixed to the actuator body 20 and holds the pressing means 33 within the actuator 2, and which includes a disk 13, ball 10 and ball retainer 11 arranged above the part of the bonnet 5 which screws into the valve body 7, and the thrust amplifier 1 is composed of the inclined surface 12 formed on the tip of the stem 32, the disk 13, the ball 10 and the ball retainer 11 which has a conical tapered surface 11a.

[0024] [Ball holder] 3 and 5(a1), the tapered surface 11a of the ball retainer 11 is composed of a central tapered surface 11a1 with which the ball 10 abuts against the valve seat 70 when the valve element 6 is in the fully open state from just before the fully closed state, and an outer tapered surface 11a2 with which the ball abuts from just before the fully closed state to the fully closed state. There are no particular limitations on the angles of the respective surfaces, but for example, the angle θ1 of the central tapered surface 11a1 can be 45° and the angle θ2 of the outer tapered surface 11a2 can be 60°.

[0025] By making the taper angle of the tapered surface 11a of the ball retainer 11 gentler with respect to the horizontal plane, i.e., the angle θ1 of the central tapered surface 11a1 and the angle θ2 of the outer tapered surface 11a2, the speed at which the valve disc 6 moves from just before the fully closed state to the fully closed state can be made slower than the closing speed of the valve disc 6 from the fully open state to just before the fully closed state. This prevents sudden collisions between the valve seat 70 and the valve disc 6, making it suitable for use in on-off valves that open and close frequently and require prevention of wear on the valve seat and valve disc. Furthermore, because the valve opens slowly from the fully closed state to a certain opening, it is possible to supply fluid while suppressing sudden pressure fluctuations, etc.

[0026] <Embodiment 2> 4 and 5(b1) are perspective views of a ball retainer 11 according to a second embodiment of the present invention. The second embodiment of the present invention is similar to the first embodiment except that the angle of the tapered surface 11a of the ball retainer 11 is different from that of the first embodiment, and therefore a description thereof will be omitted.

[0027] 4 and 5(b1), the tapered surface 11a of the ball retainer 11 in the second embodiment is composed of a central tapered surface 11a1 with which the ball 10 abuts against the valve seat 70 when the valve disc 6 is in the fully open state from just before the fully closed state, and an outer tapered surface 11a2 with which the ball 10 abuts from just before the fully closed state until the fully closed state, as in the first embodiment, and the angles of the respective surfaces are set so that the angle θ4 of the outer tapered surface 11a2 is steeper than the angle θ3 of the central tapered surface 11a1 with respect to the horizontal plane. The respective angles are not particularly limited, but for example, the angle θ3 of the central tapered surface 11a1 can be 60°, and the angle θ4 of the outer tapered surface 11a2 can be 45°.

[0028] This allows the valve seat 70 and the valve element 6 to be rapidly closed, making it suitable for use in on-off valves that require speedy opening and closing even when a thrust amplifier is used.

[0029] <Variation 1> 5(a2) and 5(b2) show a modified example of the present invention. This modified example is similar to the first embodiment except for the shape of the tapered surface 11a of the ball retainer 11, and therefore a description thereof will be omitted.

[0030] 5(a2), the tapered surface 11a is a curved surface that has a gentle angle from the center to the outer diameter side or is convex outward, and the taper angle is the tangent angle passing through the contact point with the ball, and the taper angle can be gradually made gentler, resulting in the same effects as those of the first embodiment.

[0031] The tapered surface 11a shown in Fig. 5(b2) is a curved surface in which the angle from the center to the outer diameter side is gentle or convex inward, and the taper angle is the tangent angle passing through the contact point with the ball, and the taper angle can be gradually made steeper, resulting in the same effects as those of the second embodiment.

[0032] <Variation 2> In the second modification, the inclination angle of the inclined surface 12 formed at the tip of the stem 32 is formed at a plurality of different angles in the above-described embodiment.

[0033] The inclination angle of inclined surface 12 can be set to different angles to match tapered surfaces 11a1, 11a2 with different taper angles of tapered surface 11a of ball retainer 11, or one inclination angle can be set to match both tapered surfaces 11a1, 11a2 with different taper angles, and the other inclination angle can be set to match only one of tapered surfaces 11a1, 11a2. If the inclination angle position is determined using the latter setting, the movement speed of valve element 6 can easily be set to three levels. [Industrial Applicability]

[0034] The thrust amplifier of the actuator according to the present invention can vary the moving speed of the valve disc even in an actuator incorporating the thrust amplifier, and can therefore be suitably used as a thrust amplifier for an actuator used in an on-off valve in which the speed at the moment the valve disc seats on the valve seat needs to be slowed down or quickened. [Explanation of symbols]

[0035] 1 Thrust amplifier 10 balls 11 Ball holder 12 Slope 13 discs 2 Actuators 3 Piston (drive mechanism) 32 Stem 4 Diaphragm fixing member 5. Bonnet 6 Valve body (diaphragm) 7 Valve body V-valve

Claims

1. a disk provided between an output end of an actuator that operates a valve body that opens and closes a fluid flow path and the valve body, the disk transmitting a thrust that presses the valve body; a ball presser disposed above the disk and having a conical tapered surface that widens outward and downward; a stem that passes through a through hole formed in the center of the ball retainer, extends from the drive mechanism of the actuator, and has a tapered inclined surface at its tip on the valve body side; a plurality of balls that are sandwiched between the upper surface of the disk, the tapered surface of the ball retainer, and the inclined surface of the stem and are arranged to move outward as the stem moves downward; A thrust amplifier for an actuator, wherein the tapered surface of the ball retainer that comes into contact with the ball has a taper angle formed at a plurality of different angles.

2. 2. The actuator thrust amplifier according to claim 1, wherein the taper angle is a tangent angle of a curved surface that is gentle or convex outward and that forms an angle with the vertical direction from the center side to the outer diameter side.

3. 2. The actuator thrust amplifier according to claim 1, wherein the taper angle is a tangent angle of a curved surface that is steeper or convex inward than the center side and that forms a vertical direction on the outer diameter side.

4. 4. A thrust amplifier for an actuator according to claim 1, wherein the inclination angle of the inclined surface of the stem is formed at a plurality of different angles.

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