JP6484479B2 - Valve actuator - Google Patents

Description

  The present invention relates to a valve actuator that is used in, for example, a valve that is used in an integrated piping system such as a semiconductor manufacturing apparatus, and is particularly suitable for a valve that is used in a pipe line through which a high-temperature fluid flows.

  In recent years, in semiconductor manufacturing equipment, in response to demands for higher functionality, miniaturization, and higher quality of semiconductor elements, for example, film formation is performed with a high aspect ratio on a wafer surface that is narrow and deep. Therefore, a film forming technique called ALD (Atomic Layer Deposition): atomic layer deposition is often used. According to ALD, it is possible to form a very thin film by controlling the atomic level, but the temperature of the reaction gas supplied to the chamber exceeds 200 ° C., and sometimes reaches a high temperature of 300 ° C. or higher.

  Therefore, in the valve actuator used in this type of piping system, it is difficult to use a fluoro rubber O-ring for the seal part of the drive part, and it is composed only of a metal material in order to improve high temperature resistance. In many cases, a piston-structured drive unit using a bellows-shaped bellows is employed. In this case, it is necessary to increase the thrust of the stem with an actuator in order to make the valve body of the valve integrated and installed in a predetermined space reciprocate in the direction crossing the flow path so as to be in close contact with the valve seat when the valve is closed. There is. For this reason, usually, an actuator for an integrated valve has a built-in thrust expansion mechanism.

As an actuator having a thrust expanding mechanism, for example, a controller of Patent Document 1 and an actuator of Patent Document 2 are disclosed. In these actuators, the piston is moved by air pressure, and the movement of the piston is transmitted to the stem for opening and closing the valve body against the spring while expanding the thrust through a plurality of cams.
In these cases, a cam arranged in a substantially horizontal direction is supported by a pin so as to be rotatable in the middle of the cam, the outer end of the cam is in contact with the lower surface of the piston, and the inner end is the upper part of the stem. Is engaged on the side. When the piston connected to the bellows reciprocates in the vertical direction, the up-and-down movement is amplified by the lever principle and transmitted to the stem by a cam arranged in a substantially horizontal direction.

Japanese Patent No. 4300355 Japanese Patent No. 3067977

  However, in the actuators of Patent Document 1 and Patent Document 2, since the operation of the piston is expanded to a predetermined thrust via a cam arranged in a substantially horizontal direction, the piston and the rollers that are the force points in the diameter direction of the actuator. It is necessary to secure a distance from the contact position to the pin serving as a fulcrum. In order to ensure this, the overall length of the cam is increased, and as a result, the diameter of the actuator may become a large size exceeding 60 mm, for example. Therefore, there is a possibility that this actuator cannot be mounted on a valve integrated in a limited space such as an integration block.

On the other hand, if it is attempted to reduce the overall outer diameter by reducing the diameter of the bellows of the actuator having this structure, the effective area of the piston may be reduced, and the thrust required for the opening / closing operation of the valve may not be obtained. . In order to compensate for this lack of thrust, it is conceivable to change the cam ratio. In this case, however, the distance from the pin to the roller is extended, resulting in an increase in the diameter of the actuator. Furthermore, since the spring force for returning the piston and the bellows is transmitted in inverse proportion to the cam ratio, the return force may be insufficient.
In addition, there is a multi-stage piston structure as a means to reinforce thrust while reducing the diameter of the piston, but if a bellows is provided, the inner diameter becomes narrow, so it is difficult to provide a complicated multi-stage piston structure inside the bellows structure. .

  The present invention has been developed in order to solve the above-mentioned problems, and the object of the present invention is to exhibit resistance even when a high-temperature fluid flows, and to provide thrust and return operation necessary for fluid sealing. An object of the present invention is to provide a compact valve actuator that can be mounted on a valve that is integrated and installed in a limited space.

  In order to achieve the above object, the invention according to claim 1 is directed to a stem for opening and closing a valve body as the piston moves by introducing air into a sealed space formed by a piston provided in a casing and a heat-resistant bellows. This is a valve actuator that moves the actuator against the spring mechanism. An actuator that works in conjunction with the piston is provided at the bottom of the piston, and an inclined surface that slopes toward the center is formed on the lower surface of the actuator. A cam is arranged substantially evenly on the lower surface area of the body, and this cam has a rolling part that rolls on an inclined surface at one end, an operating part that moves the stem at the other end, and a fulcrum that rotates the cam. The cam part piece between the rolling part of the cam and the shaft part is arranged in the substantially vertical direction along the moving direction of the piston to suppress the piston from expanding the diameter as much as possible. Is a valve actuator

  The invention according to claim 2 is the valve actuator in which the inclined surface is an inclined surface of a rolling groove formed uniformly on the lower surface of the operating body.

  The invention according to claim 3 is the valve actuator in which the protrusion direction provided on the piston is fitted to the fitting portion formed at the center of the upper surface of the operating body to guide the thrust direction.

  According to a fourth aspect of the present invention, a cam flange for supporting the shaft portion is provided at the lower portion of the cam of the casing, and a fixing groove for preventing the slippage is provided by fitting the shaft portion at a position facing the inclined surface of the cam flange. This is a valve actuator.

  The invention according to claim 5 is the valve actuator in which the shaft portion of the cam is rotatably mounted on the cam flange and the cam flange is fixed in the casing.

  The invention according to claim 6 is the valve actuator in which an auxiliary spring is interposed between the cam flange and the operating body, or an auxiliary spring is provided inside the bellows.

  According to the seventh aspect of the present invention, an abutting portion capable of abutting against the bottom surface of the piston is provided at the upper portion of the stem, and the abutting portion is brought into abutment with the piston at the bottom dead center side of the piston to the casing side of the cam. It is the actuator for valves which controlled rotation operation.

  According to the first aspect of the present invention, the entire structure is made of metal by introducing air into the sealed space formed by the piston and the heat-resistant bellows and moving the stem against the spring mechanism as the piston moves. Excellent resistance can be exhibited even when a high-temperature fluid flows through the product. An operating body having an inclined surface on the lower surface is provided in conjunction with the lower portion of the piston, and a cam having a rolling portion, an operating portion, and a shaft portion is arranged substantially evenly on the lower surface area of the operating body. Is arranged in the vertical direction along the moving direction of the piston to suppress the expansion of the piston as much as possible. While converting with efficiency, the diameter of the actuator can be suppressed by reducing the diameter of the piston. Accordingly, it is possible to mount a valve integrated in a limited installation space such as an integration block while maintaining compactness while ensuring a thrust necessary for sealing the fluid and a reliable return operation.

  According to the second aspect of the present invention, the rolling grooves are evenly formed on the lower surface of the operating body, thereby restricting the movement of each cam in the opening / closing operation direction of the valve by the rolling grooves. The stem can be moved up and down by operating uniformly through the rolling groove and applying an equal force from the operating portion. As a result, the stem can be operated smoothly while preventing rotation and shaft runout, and the valve control can be performed with high accuracy to ensure the sealing performance when the valve is closed.

  According to the invention which concerns on Claim 3, the shift | offset | difference and inclination of an operating body are prevented by fitting the protrusion guide part of a piston to the fitting part of an operating body, and guiding a thrust direction, and the raising / lowering operation of a piston is carried out. It can be accurately transmitted to the operating body. Therefore, the valve can be accurately controlled by moving the operating body in the axial direction and operating the cam evenly, and moving the stem smoothly.

  According to the fourth aspect of the present invention, the cam shaft portion is fitted into the fixed groove of the cam flange, so that the cam body can be easily and accurately mounted while corresponding to the position of the inclined surface of the operating body, and the load is applied from the operating body and the stem. The cam can be prevented from coming out from the fixing groove after receiving and assembling.

  According to the fifth aspect of the present invention, when the operating body moves up and down, the rolling section rolls along the inclined surface, the cam rotates about the shaft section, and this rotation can be transmitted from the operating section to the stem. . Since the cam flange is fixed to the casing, the cam mounted on the shaft is prevented from moving up and down relative to the operating body, and the cam can be operated accurately in proportion to the up-and-down movement of the operating body.

  According to the sixth aspect of the present invention, when the air is exhausted, the operating body can be operated by the auxiliary spring in the direction opposite to that when the air is supplied, and can be reliably returned to the original state.

  According to the seventh aspect of the present invention, the piston is prevented from being excessively lowered by the contact with the piston on the bottom dead center side of the contact portion, and the cam is rotated to the casing side by the operating body interlocking with the piston. This prevents the cam from inadvertently contacting and colliding with the casing and preventing the stem from rising more than necessary.

It is a longitudinal cross-sectional view which shows embodiment of the actuator for valves in this invention. It is sectional drawing which shows the valve closed state of the valve actuator of FIG. It is a partially-omission perspective view which shows an action body. It is a schematic perspective view which shows the mounting state of a cam and an action body. It is a partially-omission perspective view which shows the attachment state of a cam. (A) is a side view of a cam. (B) is a front view of a cam. It is a perspective view which shows a cam flange. It is a partially-omission perspective view which shows the attachment state of a cam. It is a graph which shows the relationship between a bellows position and a load. It is a partially expanded sectional view of FIG.

  Embodiments of a valve actuator according to the present invention will be described below in detail with reference to the drawings. 1 shows a valve open state of the valve actuator of the present invention, and FIG. 2 shows a valve closed state of the valve actuator.

  In the figure, a valve actuator (hereinafter referred to as actuator body 1) has a casing 2, a piston 3, a bellows 4, a stem 5, and a spring mechanism 6, and is mounted on an upper portion of the valve 10. An actuator 11, a cam 12, a cam flange 13, and an auxiliary spring 14 are provided inside the actuator body 1.

In the actuator body 1, the casing 2 includes an upper casing 15 and a lower casing 16, which are screwed and provided integrally.
The upper casing 15 is formed in a substantially cylindrical shape, and a disk-shaped cap 17, bellows 4, and piston 3 are accommodated on the upper side, and the operating body 11 is disposed between the lower side of the upper casing 15 and the lower casing 16. The cam 12 is stored so as to be sandwiched. An annular reduced diameter portion 18 is formed in the vicinity of the center of the inner periphery of the upper casing 15, and the upper surface of the operating body 11 abuts on the annular reduced diameter portion 18, so that the raising of the operating body 11 is restricted to a predetermined position. . An annular locking portion 19 is formed in the vicinity of the lower inner periphery of the upper casing 15.

  A cap 17 is attached to the upper opening side of the upper casing 15 via a screwed portion 20. The piston 3 is integrally attached to the cap 17 via a bellows 4 by welding, and a sealed space S is provided in the piston 3, the bellows 4 and the cap 17. As a result, the unitized piston 3, bellows 4, and cap 17 are integrated with the upper casing 15, thereby forming a sealed space S in the casing 2. A joint 21 is provided at the center of the cap 17, and air is supplied / exhausted into the sealed space S through an air supply / exhaust hole 22 provided in the joint 21. A tube (not shown) is connected to the air supply / exhaust hole 22, and the diameter of the tube is, for example, about φ 3.18 mm.

  The lower casing 16 is formed in a substantially cylindrical shape, and is provided with a spring mechanism 6 having a spring 23 and a retainer member 24 therein so that the spring mechanism 6 can be mounted. A through hole 25 for inserting a stem is formed in the center of the lower casing 16 (casing 2), and the stem 5 is provided in the through hole 25 so as to be movable up and down.

  The piston 3 is formed in a substantially disc shape, and a substantially columnar ridge guide portion 30 is formed in a projecting manner at the center thereof. In FIG. 1, the piston 3 moves in the vertical direction in the casing 2 by the introduction of air from the air supply / exhaust hole 22, and the stem 5 is interlocked with the movement to resist the spring mechanism 6, which will be described later. A valve body 31 made of a diaphragm of the valve 10 is provided so as to be operably lowered.

  A guide shaft 5 a for guiding the operating body 11 is provided at the upper portion of the stem 5, and a contact portion 26 capable of contacting the bottom surface of the piston 3 is provided at the upper portion of the guide shaft 5 a. The abutting portion 26 can abut on the piston 3 on the bottom dead center side of the piston 3, thereby restricting the rotational movement of the cam 12 toward the casing 2. A flange portion 5b for receiving the cam 12 is formed at a lower portion of the guide shaft 5a with sufficient strength. Further, in the vicinity of the lower portion of the stem 5, a contact surface 16a formed on the lower casing 16 can be contacted. The split ring 32 is fixed by fitting. On the bottom surface of the stem 5, for example, a rounded surface 5c of 25 mm is formed.

  The stem 5 is provided so as to be movable up and down in the casing 2, and a diaphragm piece 33 of a later-described valve 10 is disposed on the side of the round surface 5 c of the stem 5, and a valve body 31 is disposed below the diaphragm piece 33. A sheet 34 is disposed. Since the stem 5 is easily slid and worn by receiving the synthetic reaction force from the valve body 31, it is made of, for example, a highly rigid SUS440-based material. Although not shown, the surface is hard chrome plated. ing. The sheet is formed of, for example, a resin material, but may be a metal sheet formed integrally with a body 70 described later.

  1 and 2, the spring mechanism 6 has the above-described spring 23, retainer member 24, and split ring 32, which are mounted in the lower casing 16. The spring 23 is required to have a force to push down the diaphragm 31 and seal it when the pressure of the fluid to be used is applied to the diaphragm 31 and when the air is exhausted. This force is the force by which the fluid pushes up the diaphragm 31, the load required when the diaphragm 31 seals the valve seat to the seat 34, the reaction force of the diaphragm 31, the expansion force generated by the bellows 4 in a vacuum, and other possible losses It is set to be larger than the reaction force synthesized. These combined reaction forces are, for example, 824 N, and it is desirable to set the load at the time of setting the spring 23 to 1010 N and the load at the time of deflection to 1260 N so that more force can be exerted. The load 1260N is a force for lifting the stem 5.

Of the spring mechanism 6, the spring 23 is provided by a disc spring in order to make it compact while exhibiting a high load. The material is made of SUS304-CSP that can be used even at 300 ° C. Formed above. When a disc spring is provided, for example, if the margin is + 10% and the capacity reduction due to sag or the like is assumed to be 100N, the combined reaction force as a design value is 824N × 1.1 + 100N≈1010N. In this case, the diaphragm (valve element) The opening / closing amount of 31) is in the range of 1.5 mm.
The retainer member 24 is provided between the disc spring 23 and the split ring 32. The elastic force of the disc spring 23 is transmitted to the stem 5 by the split ring 32 via the retainer member 24 and the stem 5 is driven.

The bellows 4 is provided so as to be stretchable by a heat-resistant metal material having a use temperature of 300 ° C., for example, and, like a general compression spring, can exert a force to return to its original state when compressed. Provided. The magnitude of the reaction force is appropriately set to a predetermined value depending on the spring constant and the compression amount. When air is supplied and exhausted into the sealed space S, the piston 3 moves in the casing 2 due to the expansion and contraction of the bellows 4. At this time, the outer diameter of the bellows 4 is provided slightly smaller than the inner diameter of the casing 2, thereby preventing contact with the inner periphery of the casing 2 when the piston 3 is moved. The bellows 4 has, for example, material: AM350, outer diameter: φ32 mm, inner diameter φ19 mm, drive length: 33 to 40 mm (stroke 7 mm), spring constant: 8.2 N / mm, generated load: compression 57.4 N to set 8 N , Effective area: 5.73 cm ² .

  3 is provided at the lower part of the piston 3, and the thrust of the piston 3 moving by the bellows 4 is transmitted to the cam 12 by the actuating body 11. Open and close operation. An inclined surface 40 that is inclined toward the center is formed on the lower surface of the operating body 11, and a rolling portion 41 of the cam 12 described later is provided on the inclined surface 40 so as to be in contact therewith.

  The inclined surface 40 is provided as an inclined surface of the rolling groove 36 formed uniformly on the lower surface of the operating body 11, and is disposed at three positions at equal intervals. The inclined surface 40 is provided so that the rolling portion 41 can roll, and a side wall 42 is formed on a side portion of the inclined surface 40. As a result, the rolling part 41 rolls on the inclined surface 40 while the side surface is guided by the side wall 42, so that the operating body 11 moves up and down in the casing 2 by the rotation of the cam 12 while the rotation is suppressed. The side wall 42 prevents the rolling part 41 from coming off from the rolling groove 36.

  In FIG. 2, when setting the inclination angle θ of the inclined surface 40, when the operation amount Y of the bellows 4 (actuating body 11, piston 3)> cam opening / closing amount X and the inclination rate is smaller than 1, When the operating body 11 and the piston 3 are lowered from the state of FIG. 2 to the state of FIG. 1 and the valve 10 is opened, the cam 12 is easily rotated. However, in the closing operation of the valve 10 shown in FIGS. 1 and 2, which is the reverse operation, the cam 12 becomes difficult to rotate due to the reciprocal of the inclination rate, and the operating body 11 rises due to the lowering of the stem 5. Sometimes, the reciprocal of the magnification of the cam 12 acts to make it difficult for the operating body 11 and the piston 3 to rise smoothly.

  Therefore, it is desirable to set the inclination angle θ so that the bellows operation amount Y <the cam opening / closing amount X. In this embodiment, the inclination rate that is the cam opening / closing amount X ÷ the bellows operation amount Y is set to 1. 2 (reciprocal number 0.83), and the inclination angle θ of the inclined surface 40 was set to 50.27 °. The inclination angle θ can be set by making the bellows movement amount Y with respect to the cam opening / closing amount X close to a linear relationship, and furthermore, if the inclined surface is formed in a curved surface, it can be made closer to linear.

  As shown in FIG. 3, three bottomed holes 43 are formed at equal intervals between the inclined surfaces 40, and each of the bottomed holes 43 has an auxiliary spring 14 formed of a coil spring shown in FIGS. 4 and 5. Is provided so as to be insertable in a positioning state. In FIG. 3, a through hole 44 penetrating in the vertical direction is formed at an appropriate position of the operating body 11, and the through hole 44 prevents the occurrence of a pressure difference between the upper and lower sides of the operating body 11 in the casing 2. 11 moves up and down smoothly.

A guide hole 45 into which the guide shaft 5a can be inserted is provided at the center of the operating body 11, and the operating body is guided by the guide shaft 5a fitted in the guide hole 45 and the inner diameter surface of the upper casing 15, respectively. Thus, the positional accuracy during the up-and-down movement of 11 is increased.
In FIG. 1, a circular concave fitting portion 50 is formed at the center of the upper surface of the upper portion of the guide hole 45, and the protrusion guide portion 30 described above is fitted to the fitting portion 50, so that the operating body 11 moves. Is guided in the thrust direction.

  As shown in FIG. 1, FIG. 4, and FIG. 5, cams 12 are arranged substantially evenly on the lower surface region U of the operating body 11. 6 (a) and 6 (b), the cam 12 has a substantially L-shaped cam member 51, and a rolling portion 41 that rolls on the inclined surface 40 at one end of the cam member 51, and the like. At the end, an operating portion 52 for moving the stem 5 in the up-and-down direction, and a shaft portion 53 serving as a fulcrum for rolling the cam member 51 are provided between the rolling portion 41 and the operating portion 52 by rollers. It is done. In the cam member 51, an elongated cam portion piece 54 is formed between the rolling portion 41 and the shaft portion 53.

  As described above, the substantially L-shaped cam 12 has the rolling portion 41 on the side of the operating body 11 and the operating portion 52 and the shaft portion 53 on the side of the cam flange 13 where the operating portion 11 is positioned below the operating body 11 in FIG. The rolling part 41 is provided with a force point A that receives thrust from the operating body 11, a fulcrum B at the center of the shaft part 53, and an action point C at which force is applied from the operating part 52 to the stem 5. . The cam piece 54 is arranged in a substantially vertical direction along the moving direction of the piston 3, and the piston 3 is suppressed from expanding in diameter as much as possible.

  The cam 12 has a function of amplifying the thrust of the piston 3 by the lever principle and transmitting it to the stem 5 by the raising and lowering movement of the operating body 11, so that the stem operates in a direction reverse to the raising and lowering movement of the operating body 11. Is transmitted to. That is, as shown in FIG. 1, when the bellows 4 is extended and the piston 3 and the operating body 11 are lowered, the stem 5 is raised via the cam 12, while the bellows 4 is contracted as shown in FIG. However, when the piston 3 and the operating body 11 are raised, the stem 5 is lowered via the cam 12.

  Since the cam 12 is a component that is particularly exposed to wear and mechanical stress, for example, the rollers 41, 52, and 53 are provided with C1720B (beryllium copper) having high strength and high contact resistance as a material. 51 is provided with a high-strength SUS440 system as a material. In the present embodiment, the rolling portion 41, the operating portion 52, and the shaft portion 53 are set in a positional relationship such that the cam magnification is about 4.7 times.

A cam flange 13 for supporting the shaft portion shown in FIG. 5 is provided at the lower portion of the cam 12. The cam flange 13 mainly holds the cam 12 and is provided as a base for the upper part. In the cam flange 13, a fixing groove 60 is provided at a position facing the inclined surface 40, and both sides of the shaft portion 53 are fitted into the fixing groove 60 as indicated by arrows. As a result, the cam 12 is rotatably mounted on the cam flange 13 by the shaft portion 53. After the shaft portion 53 shown in FIG. 8 is fitted, in FIG. 1, the operating body 11, the stem 5, and the rolling body 41 are in contact with the inclined surface 40 and the operating portion 52 is engaged with the flange portion 5 b. As a result, a load is applied to the cam 5 from above, so that the cam 5 is prevented from coming off.
In this case, the fixing groove 60 is provided so as to exhibit sufficient strength because the shaft portion 53 is fitted therein and receives a strong load from the upper side or the horizontal direction when the cam 12 rotates.

In the cam flange 13 shown in FIG. 7, a bottomed holding hole 61 is provided at a position facing the bottomed hole 43, and the auxiliary spring 14 is placed in the holding hole 61 as shown in FIGS. 4 and 5. The cam flange 13 and the bottomed hole 43 of the operating body 11 are interposed in a positioned state. The auxiliary springs 14 are provided at three locations. In the air exhaust state of FIG. 2, the operating body 11 is pushed up while being held horizontally by the auxiliary springs 14, and the bellows 4 is contracted and this state is maintained. The In this case, for example, the total load when the three auxiliary springs 14 are set may be 15N, and the load when the deflection is performed may be 29.4N.
The auxiliary spring 14 may be provided inside the bellows 4 in addition to being mounted between the cam flange 13 and the operating body 11.

  As shown in FIG. 7, a communication hole 62 for inserting a stem is provided at the center of the cam flange 13, and the stem 5 is guided up and down by the communication hole 62. An annular step 63 is formed on the outer periphery of the cam flange 13, and an annular placement surface 64 is provided below the annular step 63. As shown in FIGS. 1 and 2, in the cam flange 13, the mounting surface 64 is mounted on the end surface 16 b of the upper portion of the lower casing 16, and the annular step portion 63 engages with the annular locking portion 19 of the casing 2. Thus, it is fixed in the casing 2 while being positioned up and down.

  Since the guide shaft 5a is inserted into the guide hole 45 and the stem 5 is inserted into the communication hole 62, the operation of the stem 5 is maintained on the axis. As a result, if the shaft portion 53 is fitted into the fixing groove 60 as described above, it is not necessary to fix the both ends of the auxiliary spring 14 to the holding hole 61 and the bottomed hole 43, and the operating body 11 and the cam flange. There is no need to provide a guide or the like for preventing rotation with the motor 13.

Next, the spring force when the above-described disc spring 23 and auxiliary spring 14 are provided will be described.
First, it is confirmed whether the bellows 4 is returned by the disc spring 23 when the air is exhausted. Assuming that the return force that always pushes up the bellows 4 is Fr, the return force Fr is related to the force that the surplus capacity of the disc spring 23 transmits to the cam 12 and the operating body 11 and has the following effect. expressed.
Returning force Fr = (Belleville spring load-combined reaction force) × cam magnification × actuating body inclination rate This returning force Fr is a load that is always generated on the bellows 4 even when the valve is closed. This is a material for determining whether or not the auxiliary spring 14 is necessary.

In relation to the above formula, as the above-described disc spring load, the load 1010N when set (valve closed) or the load 1260N when deflected (valve opened), the combined reaction force 824N, the cam magnification 1/5 when set .77 or cam magnification 1 / 4.79 at the time of deflection, inclination rate 1.37 × 1.2 of the actuator 11 at the time of setting, or 0.6 × 1.2 inclination rate of the actuator 11 at the time of deflection, respectively. Then, in the graph showing the relationship between the bellows position and the load shown in FIG. 9, in the upper limit position 7 mm of the bellows 4 in FIG. 2, that is, in the valve closed state, the return force Fr _up becomes minimum, that is,
Returning force Fr _up = (1010−824) × (1 / 5.77) × (1.37 × 1.2) = 53N.
On the other hand, in the lower limit position 0 mm of the bellows 4 in FIG. 1, that is, in the valve open state, the restoring force Fr _down is maximum,
The return force _{Fr down = (1260-824) × (} 1 / 4.79) × (0.6 × 1.2) = the 65.5N.

  Each follower inclination rate when the valve is closed or opened is shown in FIG. 1 where the inclination ratio tan θr of the angle θr is defined as θr when the angle formed by the straight line from the fulcrum B to the force point A with respect to the inclined surface 40 is θr. It is multiplied as a coefficient. Since the angle θr = 30.97 ° when the valve of FIG. 1 is open, the inclination rate tan θr = tan 30.97 ° ≈0.6, while when the valve of FIG. 2 is closed, the angle θr = 54.07 °. Therefore, the inclination rate tan θr = tan 54.07≈1.38. When air is exhausted, force is transmitted from the cam 12 to the operating body 11, and when air is supplied, force is transmitted from the operating body 11 to the cam 12.

  FIG. 9 shows the push-up force by the disc spring 23 when the bellows 4 expands and contracts in the stroke range from 0 mm to 7 mm, the bellows spring force when the bellows 4 expands and contracts, and the combined force thereof.

  In FIG. 9, when the restoring force (push-up force) Fr of the disc spring 23 decreases as the bellows 4 rises, the bellows drag increases in inverse proportion to the restoring force Fr. On the other hand, when the push-up force Fr of the disc spring 23 increases as the bellows 4 descends, the bellows drag decreases in inverse proportion to the push-up force Fr.

  In the load of the combined force of the push-up force and the bellows drag shown in the figure, the push-up force is larger than the bellows drag on the positive side, so that the bellows 4 is lifted by the disc spring 23 and the push-up force is on the negative side. Therefore, the force to extend downward is increased by the spring force of the bellows 4.

  That is, at the position where the combined force becomes zero when the air is exhausted in the graph, the force that the bellows 4 tries to extend downward is balanced with the force from below, and the bellows 4 cannot be raised completely on the negative side. It will be. In order to prevent this, the spring force of the auxiliary spring 14 is adjusted appropriately.

When setting the load of the spring force when the auxiliary spring 14 is set, the raised state of the bellows 4 is set as the set length, and the capacity required at this time is set as the required minimum load F3, and this load is also increased when compression is increased. Select so that F3 does not become too large. The required minimum load F3 is represented by the following formula.
Necessary minimum load F3 = {(reaction force at the bellows ascending position) − (minimum return force Fr _up of the disc spring) + actuator weight, etc. ÷ number of installation springs = {(spring constant 8.2 × 7 mm + initial load) 8.1) −53 + 2} ÷ 3 = 4.8 N, and if three auxiliary springs 14 that exert a force of 4.8 N per unit are used, the bellows 4 is moved to a predetermined position when the air is exhausted by the auxiliary springs 14. Can be raised.

Next, when air is supplied from the air supply / exhaust hole 22, the capability required when the stem 5 is raised by this air supply to open the valve is verified.
When the supply air pressure is 0.4 MPa, the stem rising minimum load F _min immediately after the valve opening operation is obtained by the following equation.
Stem lift minimum load F _min = (bellows thrust-drag (set load of auxiliary spring)) x cam magnification when valve is closed x slope of operating body when valve is closed For example, air supply pressure 0.4 MPa When substituting the bellows thrust 202.8 N at the time, the drag 5.0 N × 3, the cam magnification 5.77 when the valve is closed, and the inclination rate 0.72 × 0.83 of the operating body when the valve is closed,
Stem rising minimum load F _min = (202.8−5.0 × 3) × 5.77 × (0.72 × 0.83) ≈650.7N.

On the other hand, the stem rising maximum load F _max when fully opened is obtained by the following equation.
Maximum stem rising load F _max = (bellows thrust-drag (combined deflection load of auxiliary spring)) x cam magnification when the valve is open x inclination rate of the operating body when the valve is open. Substituting bellows thrust 202.8 N at 4 MPa, drag 9.8 N × 3, cam magnification 4.79 at valve closing, and tilting factor 1.66 × 0.83 at the time of valve closing,
Stem rising maximum load F _max = (202.8−9.8 × 3) × 4.79 × (1.66 × 0.83) ≈1144.4N. In any case, the inclination rate of the working body was set to 1 / tan θr × 0.83.

When the above-mentioned maximum stem rising load F _max 1144.4N is compared with the above-mentioned combined reaction force load 1260N at the time of deflection, the combined reaction force load is larger. It is difficult to move up and down.

Therefore, a necessary air supply pressure is obtained in order to reliably move the stem 5 up and down. In Table 1, as in the case of the air supply pressure of 0.4 MPa, the stem rise minimum load F _min and the stem rise maximum load F _max are respectively determined for the air supply pressure of 0.5 MPa and the air supply pressure of 0.7 MPa. It is. The bellows thrust was calculated from the effective area of the bellows 4. The drag force in the table is the total load when the three auxiliary springs are bent.

From the results of Table 1, when the air supply pressure is 0.5 MPa, the stem rising maximum load F _max is 1479.0 N, which is larger than the combined reaction force load 1260 N at the time of deflection. In this way, if the air supply pressure is set so that the stem rising maximum load F _max is larger than the combined reaction force load at the time of deflection, the stem can be reliably raised and the valve can be opened. Specifically, if the air supply pressure is 0.5 MPa or more, the valve opening operation is not hindered and the stem can be raised smoothly.

  1 and 2, the valve 10 on which the actuator body 1 described above is mounted is mounted while being integrated in an integrated block 75. In the body 70 of the valve 10, a diaphragm piece 33 made of a stainless alloy such as SUS304 having heat resistance, a valve body 31 made of a metal diaphragm, and a sheet 34 made of a polyimide material to be sealed by the valve body 31, are provided. These are provided in the diaphragm structure. On the upper side of the valve 10, there is provided an internal screw or external screw type screw portion 71 that can be screwed to the lower portion of the casing 2 of the actuator body 1, and the screw portion 71 is screwed in via a seal member (not shown). Connected to the actuator body 1. The diaphragm piece 33 may be formed of a heat-resistant polyimide material, or may be formed of, for example, a combination of these dissimilar materials with a lower portion made of a polyimide material and an upper portion made of SUS304.

When the stem 5 of the actuator body 1 moves up and down, thrust is transmitted to the valve body 31 via the diaphragm piece 33, and the valve body 31 is made of a sheet 34 (or metal 70 when the body 70 and the metal sheet are formed). A flow path 72 in the valve 10 is provided so as to be able to open and close. The valve 10 is provided to be connectable to, for example, a size 1/2 inch, a use temperature 300 ° C., an actuator diameter (bellows inner diameter) φ38 mm (internal effective area 5.73 cm ² ), a use pressure 0.98 MPa, and Cv at normal temperature. The value is provided with performance of 0.6 or more.

  In addition, when the actuator body 1 in the above embodiment is mounted on the valve 10, the valve 10 is in a valve-closed state at a normal time (when air is not supplied) and is in a valve-opened state when air is supplied. Although it is a closed type, it can also be provided as a normally open type that is in a valve open state during normal times (when air is not supplied) and in a valve closed state when air is supplied.

Next, the operation and action of the above-described embodiment of the valve actuator of the present invention will be described.
When air is supplied from the air supply / exhaust hole 22 in the valve closed state of FIG. 2, the air is introduced into the sealed space S formed by the piston 3, the bellows 4 and the cap 17. In the figure, it extends downward and the piston 3 descends. At this time, since the outer diameter of the bellows 4 is smaller than the inner diameter of the casing, contact with the casing 2 is prevented and the piston 3 operates smoothly, so that the bellows 4 is not damaged or damaged.

  When the piston 3 is lowered, the actuating body 11 is interlocked and lowered integrally. At this time, since the protrusion guide portion 30 of the piston 3 is fitted to the fitting portion 50 of the operating body 11, the operating body 11 is guided in the thrust direction by the piston 3, and these are accurately centered in the vertical direction. While moving up and down. Accordingly, the operation body 11 is prevented from being tilted, and each inclined surface 40 of the operation body 11 is operated while being in contact with the rolling portions 41 of the three cams 12 evenly.

  In FIG. 2, when the operating body 11 is lowered, the rolling portion 41 is guided by the inclined surface 40 of the rolling groove 36 formed on the lower surface of the operating body 11, and as shown in FIGS. The cam 12 rotates around the shaft portion 53 in the direction in which the rolling portion 41 expands, and the operating portion 52 also rotates around the shaft portion 53, and the force amplified by the lever principle through this operating portion 52. Can be transmitted to the stem 5. In this case, by guiding the rolling part 41 with the side wall 42, the cam 12 rotates smoothly along the inclined surface 40 without shaking.

  In FIG. 10, when a vertical force T is applied to the operating body 11, this force T acts on the rolling portion 41 at one end of the cam 12 in the direction of the angle α at the force point A from the inclined surface 40. At this time, the force acting on the rolling portion 41 is represented by Tcosα, and this force Tcosα is transmitted as torque by the rotation radius R around the shaft portion 53 that is the fulcrum B at the cam force point A ′. Accordingly, the cam 12 rotates counterclockwise, and the torque Tcos α · R at this time is applied to the flange portion 5b from the operating portion 52 at the other end, which is the point of action C, and the operating body 11 rotates counterclockwise to cause the flange portion 5b to rotate. By pushing up, the stem 5 moves upward.

  Thus, the cam 12 is formed in a substantially L shape, and the cam piece 54 between the rolling portion 41 and the shaft portion 53 of the cam 12 is arranged in a substantially vertical direction along the moving direction of the piston 3. As a result, the force point A, the fulcrum B, and the action point C of the cam 12 are arranged substantially in the vertical direction, and the amount of movement of the rolling portion 41 in the left-right direction is reduced to suppress the piston 3 from expanding in diameter as much as possible. Like to do. Therefore, the diameter of the actuator body 1 can be made compact. For example, by limiting the diameter of the actuator body 1 to about φ38 mm, the actuator body 1 can be mounted on the valve 10 for accumulation in a limited space.

  In addition, since the distance from the force point A to the fulcrum B is secured by the cam piece 54, the rotational radius R is increased to convert the force Tcosα into a large torque, and the torque Tcosα · R is used to convert the thrust of the stem 5 Even if the bellows thrust is reduced by reducing the effective area of the bellows 4 due to the expansion, sufficient thrust is transmitted to the stem 5 via the operating body 11 and the cam 12 without setting the air supply pressure high. it can. At this time, as described above, the rolling portion 41 is caused to roll on the inclined surface 40 on the lower surface of the working body, so that the vertical movement of the working body 11 is converted into the rotational motion of the cam 12 within a narrow diameter, thereby the stem 5. Can be converted into high-efficiency thrust with high efficiency.

  Furthermore, if the cam piece 51 is provided longer, the rotation radius R can be made longer with the same actuator diameter, and the ratio of the cam 12 can be increased, so that the thrust of the stem 5 can be improved. On the other hand, by providing the inclined surface 40 with a steep slope and reducing the inclination angle θ, the force T cos α can be brought closer to the direction of the force T in the moving direction of the operating body 11, so that the thrust of the stem 5 can be improved. In addition to these turning radii R (distance from the force point A to the fulcrum B) and the inclination angle θ, the distance from the fulcrum B to the action point C is appropriately set, so that the stem 5 is raised by the air pressure. Thus, the valve body 31 can be opened.

  When the stem 5 is raised by air supply, the abutting portion 26 of the stem 5 abuts on the piston 3 at the bottom dead center side of the piston 3 when the valve of FIG. The valve element 31 is held at the maximum opening degree by restricting the rotation operation of the cam 12, and at this time, the cam 12 is prevented from excessively rotating and coming into contact with or colliding with the inner periphery of the casing 2.

  When the air is exhausted from the air supply / exhaust hole 22 from the valve open state of FIG. 1, the cam 12 rotates clockwise around the fulcrum B by the elastic force of the disc spring 23 in FIG. Then, the stem 5 is lowered and the valve is closed, and as shown in FIG. 4B, the rolling part 41 rolls on the inclined surface 40 and the operating body 11 tends to rise. In this case, a damped force that is inversely proportional to the amplifying force when expanding the thrust at the time of air supply is transmitted to the operating body 11 via the cam 12, so that the force for raising the operating body 11 may be insufficient. There is.

  In order to solve this problem, an auxiliary spring 14 is interposed between the cam flange 13 and the operating body 11, and the cam flange 13 and the piston 3 are raised by the elastic force of the auxiliary spring 14 so that the bellows 4 is fixed. It can contract to the state of. Thereby, it is not necessary to set the spring constant of the disc spring 23 to be excessively high in order to compensate for the damped force of the cam 12 generated when the operating body 11 is raised, and a highly efficient cam structure can be designed. . If the actuating body 11 can be raised to a predetermined position when the valve is closed by the elastic force of the disc spring 23, the auxiliary spring 14 can be provided inside the bellows 4.

DESCRIPTION OF SYMBOLS 1 Actuator main body 2 Casing 3 Piston 4 Bellows 5 Stem 6 Spring mechanism 10 Valve 11 Actuator 12 Cam 13 Cam flange 14 Auxiliary spring 26 Contact part 30 Projection guide part 31 Valve body 36 Rolling groove 40 Inclined surface 41 Rolling part 50 Fitting part 51 Cam part piece 52 Actuating part 53 Shaft part 60 Fixed groove S Sealed space U Lower surface area

Claims (7)

  An actuator for a valve that introduces air into a sealed space composed of a piston provided in a casing and a heat-resistant bellows and moves a stem for opening and closing a valve body against a spring mechanism as the piston moves. An actuating body interlocking with the piston is provided at a lower portion of the piston, and an inclined surface inclined toward the center is formed on a lower surface of the actuating body, and cams are arranged substantially evenly on a lower surface region of the operating body, The cam includes a rolling portion that rolls on the inclined surface at one end, an operating portion that moves the stem at the other end, and a shaft portion that serves as a fulcrum for rotating the cam. A cam piece between the rolling portion and the shaft portion is arranged in a substantially vertical direction along the moving direction of the piston so as to suppress the diameter expansion of the piston as much as possible. Valve actuator.   The valve actuator according to claim 1, wherein the inclined surface is an inclined surface of a rolling groove formed uniformly on the lower surface of the operating body.   3. The valve actuator according to claim 1, wherein a protrusion guide provided on the piston is fitted to a fitting portion formed at a central position on the upper surface of the operating body to guide a thrust direction.   2. A cam flange for supporting the shaft portion is provided at a lower portion of the cam of the casing, and a fixing groove is provided at the position facing the inclined surface of the cam flange to prevent the shaft portion from coming out. 4. The valve actuator according to any one of items 1 to 3.   The valve actuator according to claim 4, wherein a shaft portion of the cam is rotatably mounted on the cam flange, and the cam flange is fixed in the casing.   The valve actuator according to claim 5, wherein an auxiliary spring is interposed between the cam flange and the operating body, or an auxiliary spring is provided inside the bellows.   An abutting portion capable of abutting against the bottom surface of the piston is provided at an upper portion of the stem, and the abutting portion is brought into abutment with the piston at the bottom dead center side of the piston to rotate the cam toward the casing side. The valve actuator according to any one of claims 1 to 6, wherein:

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