JP4020402B2 - Rotary actuator opening indicator - Google Patents

Description

  The present invention relates to an opening degree display device for a rotary actuator for driving and rotating a valve rod of a rotary valve that opens and closes a valve body such as a butterfly valve.

  Conventionally, an output shaft is connected via a scotch yoke to a piston that reciprocates in a cylinder under the pressure of pressure fluid, and the output shaft is driven and rotated by converting the reciprocating motion of the piston into rotational motion. Rotary actuators configured to drive the valve stem of a rotary valve such as a connected butterfly valve are known. For example, Japanese Utility Model Laid-Open No. 5-89913 (Patent Document 1) and Japanese Patent Laid-Open No. 6-207605 (Patent Document). 2) etc. In such a rotary actuator, an example of a structure for indicating an opening degree is disclosed in Japanese Patent No. 3150542 (Patent Document 3). The opening degree display device disclosed in Patent Document 3 has a structure in which an opening degree pointer is directly attached to an output shaft, and the output shaft is prevented from being pulled out by a retaining ring that is a separate part from the pointer.

  The output shaft of the rotary actuator is directly connected to the bubble, so the upper side (side away from the valve) is thin and the lower side is thick, so if the air pressure is filled inside, the pressure receiving area differs From this, a downward thrust force is generated. In the structure of Patent Document 3, the thrust force generated on the output shaft is not borne by the pointer, and the thrust force is borne by a retaining ring for preventing the separation separately from the pointer. These two parts are required, and there is a problem that the number of parts increases.

Japanese Utility Model Publication No. 5-89913 JP-A-6-207605 Japanese Patent No. 3150542

  According to the present invention, the thrust force generated at the time of output is borne in the indicator portion that displays the opening degree of the rotary actuator, so that the number of parts can be reduced.

  The present invention connects an output shaft to a piston that reciprocates in a cylinder, converts the reciprocating motion of the piston into a rotational motion, drives and rotates the output shaft, and drives a valve stem of a rotary valve connected to the output shaft. In the rotary actuator, a central ring portion that is inserted and secured to the output shaft and bears a thrust force, and extends horizontally from the central ring portion in the diametrical direction, and its tip is bent downward to form a cylinder body. And an indicator plate having an indicator portion bent upward from the position of the attachment portion, and an opening display portion that rotates integrally with the output shaft. It is characterized by that.

  The indicator portion of the indicator plate is formed by cutting and raising from the attachment portion, and the attachment portion has a frame shape from which the indicator portion is cut off.

  The indicator plate is formed of a steel plate stamped product, the plate portion extending in the diameter direction from the central ring portion, the triangular indicator portion cut and raised from the tip of the part, and the triangular indenter portion are cut off. And a triangular frame-shaped mounting portion.

  A central ring portion of the indicator plate is fixed in a retaining state by a retaining ring engaged in a recessed state in the recessed portion of the output shaft so as to bear the thrust force of the output shaft.

  The opening indicator is made of a synthetic resin dish-like member that is attached to the output shaft so as to be integrated with the rotation direction, and a scale label is affixed to the peripheral side surface thereof.

  According to the rotary actuator opening degree display device of the present invention, an indicator plate having an indicator portion as a pointer is inserted into the output shaft in a state of being removed from the central ring portion, and formed at the tip extending in the diameter direction. Since the mounting part is fitted to the piston body to prevent the indicator plate from rotating, a single member can display the opening and load the thrust force, and can reduce the number of parts. As a result, the assembly can be simplified and the cost can be reduced.

  The opening indicator is made of a synthetic resin dish-like member that is attached to the output shaft so that its rotational direction is integrated, and a scale label is attached to the peripheral side surface. The scale label is an indicator. Since the position is instructed by the unit, the opening position can be easily visually recognized from the side of the actuator, the viewing range is expanded, and the opening degree can be easily confirmed.

  Preferred embodiments of the present invention will be described in detail below. The present invention relates to a rotary actuator which is a valve stem driving device of a rotary valve provided with a rotating valve element such as a butterfly valve. In general, a rotary actuator is connected to a piston that reciprocates in a cylinder under the pressure of a pressurized fluid via a scotch yoke, and the reciprocating motion of the piston is converted into rotational motion to drive and rotate the output shaft. The valve rod of the rotary valve connected to the output shaft is driven. The present invention relates to an opening degree display device for displaying a rotation angle of an output shaft, that is, an opening degree of a valve body, in such a rotary actuator.

  The opening indication device has a central ring part that is inserted into the output shaft in a locked state and bears a thrust force, and extends horizontally from the central ring part in the diametrical direction, and its tip is bent downward to widen the cylinder body. Comprising an indicator plate having an attachment part that is attached while being held in a direction, an indicator part that is bent upward from the position of the attachment part, and an opening degree display part that rotates integrally with the output shaft, The ring portion bears the thrust force generated on the output shaft, and the indicator portion is instructed to open.

  Further, the indicator portion of the indicator plate is formed by cutting and raising from the mounting portion, and the mounting portion has a frame shape in which the indicator portion is cut out. A central ring part, a plate part extending in the diametrical direction, a triangular indicator part cut and raised from the tip of the part, and a triangular frame-shaped attachment part cut out from the triangular indenter part It is characterized by.

  The thrust force generated in the output shaft is preferably adjusted in the axial direction at the time of output by locking the retaining ring engaged with the groove portion recessed in the output shaft to the central ring portion of the indicator plate and fixing it in a locked state. Try to keep the thrust power off.

  The opening indicator is preferably made of a synthetic resin dish-like member that is attached to the output shaft so that the rotation direction is integrated, and a scale label is attached to the peripheral side surface. To be able to reduce

  The present invention relates to a rotary actuator, and the embodiment according to the drawings is directed to a butterfly valve. However, the present invention is not limited to driving a butterfly valve, and includes a rotating valve rod. It can be used for various valves as an actuator for operating a so-called rotary valve that opens and closes a valve by driving and rotating from the outside. 1 to 6, the rotary actuator rotates the reciprocating motion of the cylinder (1), the piston (2) reciprocating in the cylinder (1) under the pressure of the pressurized fluid, and the piston (2). A scotch yoke (3) for converting into motion, and an output shaft (4) for transmitting the rotational motion of the scotch yoke (3) to the valve stem, and controlling the direction of the pressure fluid applied to the piston by a desired control means. When the piston (2) is reciprocated, the output shaft (4) is rotated via the scotch yoke by the reciprocating motion of the piston to drive and rotate the valve stem.

  In the illustrated embodiment, a double piston type structure having a pair of pistons is shown. However, the structure is not limited to this, and a structure having a single piston may be used. In addition to a structure for supplying fluid, a spring return structure that moves backward by a spring may be used. The pressure fluid may be any fluid pressure such as air pressure or hydraulic pressure, and is not limited.

  Referring to FIGS. 1 and 7 to 10, a cylinder (1) includes a cylinder body (10) in which a cylindrical cylinder portion is penetrated in an axial direction, and a side cover (blocking both open end faces of the cylinder body). 11). The cylinder body (10) is formed in a cylindrical shape in which the same cross-sectional shape of a spindle shape in which the central portion (100) has a cylindrical shape and the upper and lower portions (101) and (102) have a rectangular shape is continuous from one end to the other end. The shape can be manufactured by extrusion molding of an aluminum alloy. By making the cylinder body 10 extrudeable with an aluminum alloy, the weight of the cylinder body 10 can be reduced by 30% or more compared to the conventional cast structure cylinder body. Air passages (15) and (16) penetrating in the axial direction are perforated in the upper square portion and the lower square portion.

  The upper surface (103) of the upper rectangular portion (101) of the cylinder body (10) and the lower surface (104) of the lower rectangular portion (102) are formed as flat surfaces, and the upper flat surface (103) has, for example, VDI / VDE 3845. A tap hole (106) conforming to the (NAMUR) standard is formed, and a desired accessory part can be attached. In addition, a base plate (5), which will be described later, can be attached to the lower flat surface (104) in a non-rotating state while bearing torque by rail fitting, thereby achieving easy and reliable connection of the base plate (5). It is possible. A step part (105) is formed on the upper front of the cylinder body (10), and the lower end of the nameplate (14) is brought into contact with the step part (105) to align the position so that it can be easily and accurately attached horizontally. I can wear it. Of course, the stepped portion may be formed in the lower rectangular portion (102), and the upper edge of the nameplate may be positioned in contact with the stepped portion.

  Referring to FIGS. 11 to 14, the side cover (11) that closes both end faces of the cylinder body (10) is a disk-shaped member having a shape that matches the end face shape of the cylinder body (10), and is a die-cast molded product. It is. In the present invention, since the air inlet provided in the conventional cylinder body is formed in the side cover (11), it is possible to make the cylinder body (10) into a spindle shape as described above. . The air inlet is preferably formed in accordance with the NAMUR standard. As shown in FIGS. 8 and 9, the above-mentioned closed air passage (15) is formed through the upper rectangular portion (101) of the cylinder body (10) in the axial direction, and the open air passage (16). Is formed through the lower square part (102) in the axial direction. The closed side air introduction path is provided so that the two pistons (2) in the cylinder are pushed from the outside so that the pistons move toward the center, and the closed side air introduction port of one side cover (11a) is provided. The air passage directly introduced into the cylinder from (110) and the bag-like air passage (111) formed on the upper side of the side cover (11a) communicate with the air passage (16) penetrating the cylinder body. And a bag-like air passage (112) introduced into the cylinder from the other side cover (11b).

  The air passage of the open side air introduction port is provided so as to push the two pistons in the cylinder from the inside to the outside, and an end portion is provided at the open side air introduction port (113) of one side cover (11a). Through an open air passage (114) through an open air passage (16) at the lower part of the cylinder body, it is introduced from a lower shaft hole (13) formed in the center of the cylinder body as shown in FIG. It is an air passage. The outer end of the air passage (114) that obliquely penetrates the side cover (11a) is closed with a steel ball (115). The end of the open side air passage (16) passing through the cylinder body (10) in the axial direction is sealed with a desired sealing member such as a cover packing. By using the lower shaft hole (13) as an air passage, it is not necessary to process the cylinder body, and the number of processing steps can be reduced.

  Also, by providing the side cover with open and closed air inlets, rail-like protrusions and protrusions for providing air inlets that were conventionally formed on the cylinder body are no longer necessary. Since it has the same cross-sectional shape up to the other end, extrusion molding of an aluminum alloy became possible. Also, by providing an air inlet in the side cover, it is possible to obtain sufficient strength simply by adding thickness to the upper and lower shaft holes (12) and (13), and the side wall of the cylindrical portion has the minimum thickness. I can do it. Furthermore, the side cover is a die-cast molded product, and the shape of the air inlet can be molded with a mold, and the number of processing steps can be reduced. As shown in FIGS. 1 and 14, the other side cover (11b) on the side where the open side closed air introduction ports (110) and (113) are not formed has an opening adjustment bolt (17) at its center. The reciprocating distance of the piston (2) is controlled by the extension length of the bolt (17), and the rotation angle of the Scotch yoke (3), that is, the output shaft (4) is set to 0, for example. It can be adjusted at any angle of ~ 90 °.

  Referring to FIGS. 3 and 4 and FIGS. 15 to 17, the piston (2) reciprocating in the cylinder (1) is composed of a pair of left and right pistons, and air pressure acts in the cylindrical portion (100) of the cylinder body. Receiving and reciprocating in the axial direction. As shown in FIG. 15, the piston (2) is composed of a disk-shaped piston portion (20) and two parallel piston arms (21) extending integrally from the piston portion in the axial direction. Provided. A piston packing (22) is attached to the piston part (20) and is divided into two pressure chambers. The inner pressure chamber is formed between a pair of opposing pistons (2), and the outer pressure chamber is formed between the piston (2) and the side cover (11). When air pressure is introduced from the air passage described above, the piston (2) reciprocates so as to approach or separate from each other.

  A trunnion pin (23) is press-fitted to the tip of the two piston arms (21) extending integrally from the piston portion (20), and is pivotally attached to the outer periphery of the trunnion pin (23). A roller (24) is rotatably mounted on the shaft. The trunnion pin (23) is engaged with the yoke groove (30) of the Scotch yoke (3) attached to the output shaft (4), and when the piston (2) moves in the axial direction, the yoke groove (30 ), The trunnion pin (23) moves smoothly by the rotation of the roller (24), and the scotch yoke (3) rotates. Since the output shaft (4) is integrally connected to the scotch yoke (3) by a spring pin (40), the output shaft (4) rotates as the scotch yoke (3) rotates.

  Referring to FIGS. 15 and 16, a sliding ring (25) is wound around the disk-like piston portion (20) so as to be located outside the piston packing (22). Further, a plate-like sliding material (26) is attached to the tip of the piston arm (21), and the sliding ring (25) and the sliding material (26) are connected to the cylinder body (10) at two locations. Since it is slidably contacted with the inner surface and supported at two locations, stable movement of the piston is guaranteed. As shown in FIG. 17, the sliding member (26) is formed in an arc surface that follows the inner surface of the cylindrical portion of the cylinder body (10), and can be in close contact with the inner surface of the cylinder body (10). The sliding member is attached by inserting the two mounting legs (27) planted on the back surface of the sliding member into the mounting hole (28) of the piston arm.

  Referring to FIG. 17, the mounting leg (27) is not erected in the direction orthogonal to the back surface of the sliding member (26), but is obliquely planted in the direction orthogonal to the axial direction of the cylinder. The tip of the sliding member (26) is positioned so as to cover the end of the trunnion pin (23) press-fitted into the piston arm (21), and when the trunnion pin (23) loosens and comes out, Stops coming out by hitting the tip. At this time, the trunnion pin (23) that is about to come out comes into contact with the sliding material (26), and the force that pushes the sliding material outward acts, but as described above, the mounting leg (27) is in the axial direction. Because it extends in the direction orthogonal to the outer surface, it is possible to counteract the outward force applied to the tip of the sliding material with the mounting leg, and effectively prevent the trunnion pin (23) from coming out. .

  As shown in FIG. 18, the piston (2) is a die-cast molded product, and its surface is left as the cast surface except for the mounting surface (29) of the sliding material. The surface mounting surface (29) to which the mounting member is mounted is ground to a smooth surface, so as to improve the dimensional accuracy when the sliding member (26) is mounted. Note that the attachment of the sliding member (26) is not limited to the insertion by the attachment legs, but may be adhesion by an adhesive, an adhesive tape or the like. In this case, since the mounting surface (29) is polished smoothly, adhesion is easy and stronger adhesion can be achieved. The corner peripheral portion of the sliding member (26) is chamfered or rounded to prevent damage to the inner surface of the cylinder.

  As the sliding ring (25) and the sliding material (26), a resin material excellent in wear resistance and corrosion resistance, for example, a phenol resin with cloth, a polyacetal resin, or the like is preferable. Also, between the cylinder body (10) and the piston (2) that slide against each other, grease with excellent wear resistance, chemical resistance, and sliding property, such as silicon grease, grease containing molybdenum disulfide, lithium soap Base grease or the like is preferred.

  FIGS. 19-21 has shown the Example which provided the means for detecting the abrasion degree in the surface of the sliding material (26). For example, the sliding material (26) shown in FIG. 19 is projected on the surface of the sliding material (26). A plurality of projections (260) are provided, and the wear state of the sliding member (26) is grasped based on the degree of wear of the projections (260). In FIG. 20, a groove (261) is cut on the surface of the sliding member (26), and the degree of wear is detected by the depth of the groove. In FIG. 21, the sliding material (26) has a two-layer structure with different colors, and the degree of wear is detected by exposing or seeping through the back-side layer (262). By grasping the wear state, it is possible to grasp the applied state such as the opening and closing speed of the cylinder and the air pressure and the operating state such as the number of opening and closing.

  4, 10 and 22 to 24, the output shaft (4) has a columnar shaft portion (41) located in the cylinder and a small diameter opening indication extending upward and outward from the piston (2). It consists of a shaft portion (42) and a large-diameter valve stem connection shaft portion (43) extending from below the piston. (44) is a hole for press-fitting a spring pin (40) for connecting to the scotch yoke (3). The opening indication shaft part (42) has an oval cross-sectional shape with both sides of the circle cut off, and the lower valve stem connection shaft part (43) has a cylindrical shape with a rectangular interior and open downward. None, the outer peripheral surface is formed in a square irregular cross section.

  Referring to FIGS. 1, 10 and 22, an opening degree display device (6) is attached to the upper opening degree display shaft part (42). The opening indication device (6) comprises an indicator plate (60) and an opening indicator (61), and is coaxial with the indicator plate (60) fixed to the cylinder body (10) and the output shaft (4). The opening degree is displayed by reciprocal rotation with the rotation indicator (61) that rotates integrally. The indicator plate (60) is configured to receive the thrust force of the output shaft (4) by engaging the C-shaped retaining ring (62) with the small-diameter groove portion (45) of the output shaft and fixing it in the removal state.

  Referring to FIGS. 10 and 25 to 27, the indicator plate (60) is provided as a stamped product of a steel plate, and a doughnut-shaped central ring portion (600) is inserted into the output shaft, and the diameter is increased from the central ring portion. The triangular indicator portion (601) is vertically cut upward at the tip of the plate portion extending in the direction, and the triangular frame from which the triangular indicator portion is cut is bent downward, and the cylinder body (10) Fit the indicator plate (60) to the upper corner of the cylinder body (10) in a non-rotating state by fitting to the vertical surface. In this way, the indicator plate (60) is mounted by fitting it into the cylinder body with the triangular mounting part (602) bent downward, so the indicator plate (60) is fixed with bolts etc. as before. There is no need to do it.

  The opening indicator (61) is a flexible synthetic resin dish-like member having an oval center hole (610) into which the oval opening indication shaft portion (43) is inserted. A scale label (611) shown in FIG. 28 is attached to the peripheral side surface. The indicator plate (60) is formed of a triangular indicator part and mounting part cut and raised up and down, and fitted into the cylinder body (10), and fixed to the groove part (45) of the output shaft with a C-shaped retaining ring (62). Thus, it can receive both thrust direction and thrust plate functions by receiving a force in the thrust direction.

  Referring to FIGS. 10, 22 and 29, the valve rod connecting shaft portion (43) of the output shaft (4) extending from the lower portion of the cylinder body (10) has a rectangular tube shape inside, and an irregular shaped square tube outside. A cylindrical shaft portion having a shape, which is formed to have a larger diameter than the central cylindrical shaft portion (41) and extends into a base plate (5) fixed to the lower portion of the cylinder body (10). The base plate (5) is a die-cast molded rectangular plate-shaped member, and a recess (50) for receiving the valve stem connection shaft portion (43) is formed at the center. In the recess (50), the shaft portion ( The stopper (51) is inserted into the outer periphery of 43) in a non-rotating state. An opening adjustment bolt (52) is screwed into the recess (50) so as to be able to advance and retreat from the side surface of the base plate (5), and the tip of the adjustment bolt abuts against the stopper so that the output shaft (4) ) Is stopped. The rotation angle of the stopper, that is, the rotation angle of the output shaft can be adjusted by the advancement length of the opening adjustment bolt (52).

  As shown in FIGS. 10 and 29, the stopper (51) is a ring-shaped member having an outer peripheral surface having a substantially rectangular irregular cross section and an inner peripheral surface having a square irregular cross section matching the outer peripheral surface shape of the upper end of the valve stem. Therefore, further rotation is stopped by the contact of the opening adjustment bolt (52) with the outer peripheral surface. Further, the inner peripheral surface is extrapolated to the upper end of the valve stem and rotates integrally with the valve stem.

  In addition, the upper end of the shaft portion (43) of the valve rod penetrating the base plate (5) from below is engaged inside the rectangular tube shape, and the valve rod is driven integrally with the output shaft (4). It is rotated. (53) is a gasket. In the structure shown in the figure, the opening adjustment bolt (52) is provided only on one side on the closed side, but is not limited thereto. Of course, it may be arranged only on one side of the open side or on both sides of the open / close.

  On the upper surface of the base plate (5), fitting rails (54) are provided in parallel so as to be located on both sides of the recess (50). The width of the fitting rail (54) is equal to the lateral width of the lower surface of the cylinder body (10), and the base plate (5) is fitted to the lower surface of the cylinder body (10) by fitting the rail to the lower surface of the cylinder body. Connected with a non-rotating state. Since the rotation torque is borne by the joining of the rail and the main body, the base plate (5) can be fixed to the cylinder main body with only two fixing bolts (55), and the rotation torque is borne as in the past. Therefore, it is not necessary to use four bolts.

  The base plate (5) is disposed between the actuator and the rotary valve, and the output shaft of the actuator and the valve rod are connected in the base plate (5), and the opening degree adjusting means is provided in the base plate, in other words, the output shaft. The valve body or the valve opening is adjusted. That is, since the opening adjustment of the connection between the actuator and the valve stem is performed via the base plate, the connection between the actuator and the valve body can be easily performed and the change in specifications can be easily handled. I can do it. In addition, the base plate functions as an intermediate part that connects the cylinder and valve, and by selecting multiple base plates corresponding to the cylinder output and valve diameter, the base plate can be selected appropriately according to the fluid specifications. It becomes possible. In addition, since the parts such as stoppers for adjusting the opening degree that are conventionally arranged in the cylinder body are arranged in the base plate, the cylinder body can be miniaturized.

  Note that the detent connection between the base plate (5) and the cylinder body (10) is not limited to the fitting rail (54), and the upper surface of the base plate (5) is a width corresponding to the width of the cylinder body (10). It is also possible to form a fitting groove structure that is recessed in the step and fit the lower part of the cylinder body (10).

Overall perspective view Overall front view Central cross-sectional plan view Same vertical profile side view Same left side view Bottom view Front view of cylinder body Side view Same vertical profile side view An exploded perspective view of the opening indicator and base plate External view of one side cover Inside view External view of the other side cover Inside view Perspective view of piston Cross section of the main part Sectional view showing the mounting state of the sliding material Same perspective view Perspective view showing one deformation of sliding material The perspective view which shows the other deformation | transformation of a sliding material The perspective view which shows other deformation | transformation of a sliding material Front view of output shaft Plan view Bottom view Top view of indicator plate Front view Side view Scale label development Cross section of base plate

Explanation of symbols

(1) Cylinder
(10) Cylinder body
(11) Side cover
(12) Upper shaft hole
(13) Lower shaft hole
(14) Nameplate
(15) Closed air passage
(16) Open side air passage
(17) Opening adjustment bolt
(100) Cylindrical part
(101) Upper square part
(102) Lower square part
(103) Upper flat surface
(104) Lower flat surface
(105) Step
(106) Tap hole
(110) Closed side air inlet
(111) Bag-shaped air passage
(112) Bag-like air passage
(113) Open side air inlet
(114) Diagonal air passage
(115) Steel ball
(2) Piston
(20) Piston part
(21) Piston arm
(22) Piston packing
(23) Trunnion pin
(24) Roller
(25) Sliding ring
(26) Sliding material
(27) Mounting legs
(28) Mounting hole
(29) Mounting surface
(260) Protrusion
(261) Groove
(262) Layers with different colors
(3) Scotch York
(30) Yoke groove
(4) Output shaft
(40) Spring pin
(41) Cylindrical shaft
(42) Opening display shaft
(43) Valve stem connecting shaft
(44) Spring pin hole
(45) Small diameter groove
(5) Base plate
(50) Recess
(51) Stopper
(52) Rotation adjustment bolt
(53) Gasket
(54) Mating rail
(55) Fastening bolt
(6) Opening indicator
(60) Indicator plate
(61) Opening indicator
(62) C type retaining ring
(600) Central ring
(601) Indicator section
(602) Triangular mounting
(610) Center hole
(611) Scale label

Claims (5)

  The output shaft is connected to a piston that reciprocates in the cylinder, the reciprocating motion of the piston is converted into rotational motion, the output shaft is driven and rotated, and the valve stem of the rotary valve connected to the output shaft is driven. In a rotary actuator, a central ring part that is inserted into the output shaft in a non-removed state and bears a thrust force, and extends horizontally from the central ring part in the diametrical direction and bends its tip downward to make the cylinder body in the width direction. An indicator plate having an attachment part that is attached while being held, an indicator part that is bent upward from the position of the attachment part, and an opening degree display part that rotates integrally with the output shaft. Opening display device to do.   The opening degree display device according to claim 1, wherein the indicator portion of the indicator plate is formed by cutting and raising from the attachment portion, and the attachment portion has a frame shape from which the indicator portion is cut off.   The indicator plate is formed of a steel plate stamped product, the plate portion extending in the diameter direction from the central ring portion, the triangular indicator portion cut and raised from the tip of the part, and the triangular indenter portion are cut off. The opening degree display device according to claim 1 or 2, comprising a triangular frame-shaped attachment portion.   The center ring portion of the indicator plate is fixed in a retaining state by a retaining ring engaged in a retaining state in a recessed groove portion of the output shaft so as to bear the thrust force of the output shaft. The opening degree display device according to 1. The opening degree indicator is made of a synthetic resin dish-like member that is attached to the output shaft so as to be integrated with the rotation direction, and a scale label is attached to the peripheral side surface thereof. Opening display device.

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