JPH0130699Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an electric motor that effectively supplies lubricant to the threaded part of the lead screw and the movable body that is screwed into the lead screw, thereby preventing wear and rust on the threaded part. This invention relates to a valve operating device.

Generally, a control valve driven and controlled by an electric motor is equipped with a valve operating device that converts the rotational movement of the output shaft by the electric motor into linear movement, and moves the valve shaft of the valve body linearly in the axial direction. . in this case,
Conventionally, a crank mechanism or a linear motion conversion mechanism using a rack and pinion has been widely used as a linear motion conversion mechanism. However, the former has the disadvantage that the input/output positioning characteristics become non-linear due to its mechanism, and the latter requires a large torque on the input side in order to obtain the strong thrust at the closed position of the valve, which is strongly required for valve operation. However, in addition to requiring a large electric motor, it was difficult to ensure the durability of the rack and pinion tooth surfaces.

Therefore, one possibility to solve these problems is to adopt a linear motion mechanism using a lead screw and lead nut, but in that case, a bearing structure that can withstand a large thrust is required, and the threaded surfaces of the lead screw and lead nut are lubricated. Another problem to be solved arises, such as how to effectively replenish the agent, reduce wear, rust, etc. even during long-term use, and ensure smooth power transmission.

The present invention has been developed in view of the above points, and has lubricant stored inside a movable body that is screwed onto the lead screw and moves in the axial direction as the screw rotates, so that lubricant is stored inside the movable body that is moved in the axial direction as the screw rotates. The extremely simple structure of immersing the threaded part prevents wear and rust on the lead screw and the screw hole of the movable body, improving durability, and efficiently collecting lubricant adhering to the threaded part by the movable body. The present invention provides an electrically operated valve operating device that can perform the following operations.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Fig. 1 is a vertical cross-sectional view showing one embodiment of the electric valve operating device according to the present invention, Fig. 2 is a plan view of the device with the cover removed, Fig. 3 is an enlarged cross-sectional view taken along the line of Fig. 1; FIG. 4 is a sectional view taken along the line shown in FIG. 2.

In these figures, the electric valve operating device, which is designated as a whole by reference numeral 1, includes an electric motor 2, a reduction gear mechanism 3, a linear motion mechanism 6 including a lead screw 4 and a movable body 5,
Consists of main parts such as bearings 7 and 8 and mechanical parts,
It is disposed above the control valve 9 via a yoke 10. Note that the control valve 9 has an upper lid 1 that constitutes the valve body.
When the valve shaft 12 with one end protruding above the valve shaft 1 is moved up and down by the electric valve operating device 1, a valve plug (not shown) provided at the inner end of the valve shaft 12 is operated. Seat ring (not shown)
Since this constitutes a conventionally well-known two-way valve or three-way valve for controlling the opening and closing of the hole, detailed configuration and explanation thereof will be omitted.

In this embodiment, the electric motor 2 is an AC motor or a DC motor having a rotating output shaft, and is fixed to the frame 13 with a mounting screw 14. The frame 13 is formed into a substantially U-shape, so that a pair of mounting portions 13A, 13 facing each other are provided.
B, and a base 13C that connects these pair of mounting parts 13A and 13B, one of the mounting parts 13A
The electric motor 2 is disposed on the outer surface of the other mounting portion 13B, and the bearing 7 is disposed coaxially with the electric motor 2 on the outer surface of the other mounting portion 13B.
The tip of 5 is rotatably supported.

As appropriately shown in FIG. 3, the bearing 7 has a hollow cylindrical bearing mounting body 17 that is fitted and fixed from the outside into a through hole 16 provided in a mounting portion 13B. The tip end of the output shaft 15 is inserted through a radial bearing 19, rotatably supported by a thrust bearing 18, and movement in the axial direction is prevented by a screw 26, which will be described later. A thrust bearing 1 is provided on the outer peripheral surface of the tip of the output shaft 15.
8 is fitted with a retaining ring 20 for receiving thrust in the right direction in the figure, and a semicircular recess is formed in the distal end surface of the shaft 15, and a ball 21 is fitted into this recess and fixed by caulking. ing. A male thread 22 is formed on the outer peripheral surface protruding from the through hole 16 of the bearing mounting body 17, and a female thread is formed on the inner peripheral surface of the male thread 22 to form a cap 2.
3 is screwed on, and is prevented from loosening by a set screw 24. This cap 23 is nut 25
It has a screw 26 screwed in through the screw 2.
The ball 21 is supported at the tip end surface of the output shaft 15, allowing fine adjustment of the output shaft 15 in the axial direction and supporting leftward thrust. The bearing mounting body 17
Further, a highly viscous lubricant 27 such as grease is sealed inside, and thereby the thrust bearing 18, the radial bearing 19 and the balls 21
This prevents wear, rust, etc. of the output shaft 15, and reduces the friction torque of the output shaft 15. On the other hand, the base of the output shaft 15 is connected to one mounting portion 1 of the frame 13.
The output shaft 15 is inserted and held in a bearing hole 28 formed at 3A to position the output shaft 15.

The reduction gear mechanism 3 includes a worm 30 provided at the intermediate portion of the output shaft 15 and located between the pair of attachment portions 13A and 13B, and a worm wheel 31 that meshes with the worm 30 at all times. In this case, for convenience of explanation, FIGS. 1 and 2 show an example in which the worm 30 is formed integrally with the output shaft 15, but in an actual device, the worm 30 and the output shaft 15 are formed integrally as shown in FIG. It is common sense and desirable to form them as separate members and connect them using a suitable shaft coupling 29. The worm wheel 31 is fitted onto the upper end of the lead screw 4, which is disposed in a direction perpendicular to the output shaft 15 (vertical direction) with a predetermined distance between the shafts, and is secured by a nut 32. Fixed. The lead screw 4 is disposed above and coaxially with the valve shaft 12, and is supported by a bearing 8 so as to be rotatable and prevented from moving in the axial direction.

As shown in FIG. 1, the bearing 8 includes a pair of upper and lower bearing mounting bodies 33 through which the screw 4 commonly passes.
34, and a pair of thrust bearings 35, 36 are housed inside these bearing mounting bodies 33, 34 to pivotally support the lead screw 4. In this case, the pair of thrust bearings 35 and 36 are connected to the lead screw 4.
They are arranged above and below a collar 37 that is integrally provided on the outer periphery of the. The pair of bearing fittings 33 and 34 have a male threaded portion 33a provided on the outer circumferential surface of the lower end of the upper bearing fitting 33 and a female threaded portion 34a provided on the inner circumferential surface of the upper end of the lower bearing fitting 34. By screwing them together, they are separably coupled, and the frame 13 and the cylinder body 4 are connected by a presser flange 38, which will be described later.
Fixed in position relative to 0. The lead screw 4 is provided in the through holes 41 and 42 formed in the upper and lower surfaces of the bearing mounting bodies 33 and 34, respectively.
Radial bearings 43 and 44, which rotatably support the radial bearings, are press-fitted and fixed, respectively.

The base 13C of the frame 13 is connected to the cylindrical body 40.
It is firmly fixed to the upper end surface of the bearing body by a plurality of mounting screws 45, and a fitting hole 46 into which the lower bearing mounting body 34 is fitted is provided in the center. Further, the lower bearing mounting body 34 is also fitted into the inner hole 47 of the cylinder body 40, and the lower surface of the fitting body is abutted and latched to a stepped portion 48 provided on the upper end opening side of the inner hole 47. This prevents it from being inserted into the cylindrical body 40 any further. On the other hand, the presser flange 38 is fitted onto the outer periphery of the upper bearing mounting body 33. This presser flange 38 has a plurality of screw mounting holes formed near the outer periphery, each of which has a mounting screw 50 inserted therein.
is inserted into the upper end surface of the cylindrical body 40 through the attachment hole 51 provided in the base 13C of the frame 13.
is pressed downward, thereby pressing the lower bearing mounting body 34 against the stepped portion 48. Therefore, the pair of bearing mounting bodies 33 and 34 are coaxially and firmly fixed to the cylinder body 40 in a screwed-together state. Note that when the upper bearing mounting body 33 is screwed into the lower bearing mounting body 34, the pair of thrust bearings 35 and 36 come into contact with the collar 37, so that play in the axial direction of the lead screw 4 can be eliminated. . In addition, the frame 13 has a mounting portion 13A.
has the bearing hole 28 for positioning the electric motor 2 at a predetermined location, and by positioning and fixing itself on the cylindrical body 40, the worm 30 and the worm wheel 31, in other words, the output shaft 15 and the axis of the lead screw 4. The distance can be set with high precision.

The cylindrical body 40 has a lower end fitted into a fitting hole 54 provided at the center of the frame 53, and a nut 56 is screwed onto the downwardly protruding end of the frame 53, so that the cylindrical body 40 can be attached to the frame 53. 53 and is fixed upright. In this case, the cylinder 40 is connected to the pin 55
is positioned and prevented from rotating. A movable body 5 is disposed in the lower part of the interior of the cylinder 40 and is moved in the vertical direction as the lead screw 4 rotates.
is slidably inserted.

The movable body 5 has an outer cylinder 57 and an inner cylinder 58 disposed coaxially within the outer cylinder 57, and the outer cylinder 57 is slidably inserted into the inner hole 47 of the cylinder body 40. . The inner cylinder 58 is a guide block 6 which will be described later.
0 constitutes an oil tank 61, and this inner cylinder 5
The lower end of a lead nut support 63 is slidably inserted into the upper end opening of the lead nut support 63 via an O-ring 62. The lead nut support 63 is formed in a hollow shape, and its upper end is connected to the inner hole 64 of the outer cylinder 57.
It is fixed by welding, etc. Further, a lead nut 65 made of a material with excellent wear resistance and low friction is press-fitted into the inside of the lead nut support 63 and fixed by caulking. This caulking fixation is performed by bending the upper end opening of the lead nut support 63 toward the center and pressing it against the upper surface of the lead nut 65. The lead screw 4 is inserted into the screw hole 65A of the lead nut 65.
A male threaded portion 66 provided on the outer peripheral surface of the lower end portion is screwed.

The guide block 60 that constitutes the oil tank 61 together with the inner cylinder 58 is fitted into the lower end opening of the inner cylinder 58 and fixed by welding.
The lower end opening of 8 is sealed. And inner cylinder 5
8 contains lubricant 67 such as lubricating oil and grease.
This prevents the external threaded portion 66 of the lead screw 4 and the lead nut 65 from being worn out due to lack of oil film or lack of oil, thereby ensuring smooth rotation of the lead screw 4.

By the way, as mentioned above, when an AC motor or a general DC motor is used as the motor 2, if the motor 2 is forced to stop while the current is on, problems such as overheating often occur in the motor 2, and the output torque characteristics of the motor 2 is not constant based on the input signal alone, and has load followability, so excessive stress is applied to various parts of the electric valve operating device 1 and the control valve 9 side, often causing problems. Therefore, in order to prevent such a malfunction, a buffer spring 68 constituting a buffer mechanism is interposed between the outer cylinder 57 and the inner cylinder 58, and when the control valve 9 is fully closed, the buffer spring 68 is compressed more than when it is assembled. The electric motor 2 is stopped when the compressor is further compressed by a predetermined amount. Therefore, the buffer spring 68 has a pair of spring receivers 69 that are fitted to the outer peripheries of the inner cylinder 58 and the guide block 60 so as to be able to move up and down.
The bullet is loaded between A and 69B, and the upper spring receiver 69A
A retaining ring 70 fitted to the outer peripheral surface of the upper end of the inner cylinder 58 prevents the inner cylinder 58 from coming off. On the other hand, the guide block 6 allows the lower spring receiver 69B to come out downward.
This is prevented by the large diameter portion 60A provided at the lower end of the 0. The stopper 71 is fitted onto the outer peripheral surface of the guide block 60 so as to be prevented from rotating, and its outer peripheral edge is fitted into the lower end opening of the outer cylinder 57 and fixed by caulking or the like. This rotation is prevented by using a pair of axially symmetrical protrusions 72 and notches 73 provided on the inner and outer circumferential surfaces of the stopper 71, respectively, as shown in FIG. This is done by engaging with a pair of engagement grooves 74 (see FIG. 1) provided on the surface. Also,
The stopper 71 is fixed by caulking by bending the lower end opening of the outer cylinder 57 toward the center, pressing the stopper 71 from below, and pressing the stopper 71 into the step 75 provided on the inner peripheral surface of the lower end opening, similar to the upper lead nut mounting body 63. Just press it. At this time, a portion of the lower end opening of the outer cylinder 57 bites into the notch 73, thereby firmly preventing the stopper 71 from rotating.

Incidentally, the incorporation of the buffer spring 68
8 is elastically mounted between a pair of spring receivers 69A and 69B with a retaining ring 70, and a guide block 6.
0 is inserted from the lower end opening of the outer cylinder 57, and the stopper 71 is fitted into the lower end opening of the outer cylinder 57 and fixed by caulking. Mounted internally. Note that a stepped portion 88 for locking the spring receiver 69A is provided on the inner circumferential surface of the outer cylinder 57.

A screw hole 76 is formed in the center of the lower surface of the guide block 60, and a connecting bolt 77 is screwed into the screw hole 76 via a nut 78. A bolt 80 is disposed in the head 77A of the connecting bolt 77 so as to pass through the bolt 77 in the diametrical direction, and is fixed by a pair of nuts 81 and 82. The tip of the bolt 80 is formed sharply to form a pointer, and the pair of left and right connecting fittings 83, 84 are connected to the bolt 7 together with the pair of nuts 81, 82.
It is fixed at 7. The connecting fittings 83 and 84 have insertion holes (not shown) provided at their straight upper ends that are in close contact with both sides of the head of the connecting bolt 77, respectively, and the bolt 80 is inserted into these insertion holes. There is. On the other hand, the lower end portions of the connecting fittings 83 and 84 are bent into a substantially hook shape, with their tips facing each other, and the upper end portion of the valve stem button 85 is held between these lower end portions. The valve stem button 85 is connected to the valve stem 1.
2, and its upper surface abuts the lower surface of the head 77A of the connecting bolt 77. In addition, the upper end of a locking fitting 86 formed in a substantially L-shape is fixed to the bolt 80 by a nut 87, and the lower end of the locking fitting 86 is fixed to the bolt 80.
It is formed in a U-shape when viewed from above in FIG. 1, and prevents the valve shaft 12 from rotating by engaging with the outer periphery of the hexagonal portion of the valve shaft button 85.

The rotation of the movable body 5 itself is prevented by a pair of left and right rollers 90 and 91, as shown in FIG. These pair of rollers 90 and 91 are rotatably supported via spacers 94 at intermediate portions of roller support pins 92 and 93, respectively, which are attached to the outer peripheral surface of the upper end of the outer cylinder 57 from inside the outer cylinder 57. has been done. the pair of roller support pins 92;
Nuts 93 are respectively projected to the outside from elongated holes 95 and 96 formed in the axial direction on the circumferential surface of the cylindrical body 40, and nuts 98 are respectively screwed to the projecting ends via washers 97. The pair of rollers 90 and 91 are located within the respective elongated holes 95 and 96 to prevent the movable body 5 from rotating. Therefore, when the lead screw 4 rotates, the movable body 5 moves only in the vertical direction, and at this time, the pair of rollers 90, 91 contact the wall surfaces of the elongated holes 95, 96 and rotate, so that the cylindrical body Reduces frictional resistance with 40.

An electric motor 2 is mounted on the base 13C of the frame 13 in correspondence with the pair of roller support pins 92 and 93.
A switch mechanism 100 and a position detection mechanism 101 are provided.

As shown in FIGS. 2 and 4, the switch mechanism 100 includes a slide cam 103 that is slidably held by a pair of vertically arranged rails 102a and 102b, and this slide cam 10.
A pair of micro switches 1 arranged on both sides of 3
04,105.

The slide cam 103 is fixed to the upper end of a threaded rod 106, and the lower end of the threaded rod 106 is connected to a hole 107 provided in the base 13C of the frame 13.
It is threadedly connected to a connecting rod 108 that extends below the frame 13 and is rotatably supported by the tip of the roller support pin 92 . Therefore, when the movable body 5 moves up and down, the threaded rod 10
6 moves up and down together with the roller support pin 92, the slide cam 103 moves up and down along the pair of rails 102.
a, 102b. Further, on both sides of the slide cam 103, projections 110 and 11 have inclined cam surfaces 112 and 113, respectively.
1 is integrally provided. the cam surface 112,
113 are formed so that their inclination directions are opposite to each other as shown in FIG. 4, and these cam surfaces 1
12, 113, the pair of micro switches 10
Rollers 117 attached to each of the elastic pieces 116 of 4 and 105 are pressed against each other.

In this case, when the slide cam 103 rises with the rise of the movable body 5, the cam surface 112 gradually presses the roller 117 of the micro switch 104, elastically deforming the elastic piece 116, and the slide cam 103
When the motor reaches the highest position, the switch 104 is closed and the electric motor 2 is stopped by the signal at this time. On the other hand, as the movable body 5 descends, the slide cam 1
03 descends, the cam surface 113 gradually presses the roller 117 of the micro switch 105 and elastically deforms the elastic piece 116 of the switch 105, so when the slide cam 103 reaches the lowest position,
The micro switch 105 is closed, thereby stopping the electric motor 2.

The position detection mechanism 101 is for detecting the opening degree of the control valve 9 as the movable body 5 moves up and down, and sending the detection signal to an appropriate display or control means.
Similar to the switch mechanism 100, a pair of rails 1
It has a slider 121 that is slidably held in the vertical direction by 20a and 120b, and a wiper 122 of a potentiometer shown in FIG. 2 is disposed on one side of the slider 121, and a resistor 123
is in elastic contact with. The slider 121
is fixed to the upper end of a threaded rod 124, and the lower end of this threaded rod 124 is threadedly connected to a connecting rod 125 that extends below the frame 13 and is rotatably supported by the roller support pin 93. There is. Therefore, when the movable body 5 moves up and down, the threaded rod 124 moves up and down together, so the slider 121 moves up and down along the pair of rails 120a and 120b. As a result, the wiper 122 and the slider 12
1 and changes the contact position with the resistor 123, thereby changing the resistance value of the position detection mechanism 101.

The switch mechanism 100 and the position detection mechanism 101 are respectively housed in cases 127 and 128 fixed to the upper surface of the base 13C of the frame 13.

As shown in FIG. 1, the frame 53 on which the cylindrical body 40 is erected and fixed is placed on the upper surface of the yoke 10 and is firmly fixed by a plurality of bolts 130. A lower end opening of a cover 131 that covers the electric valve operating device 1 is fixed by a set screw 132 . The yoke 10
is formed into a substantially U-shape, and its lower end is fitted into the upper part of the upper lid 11 and fixed by two setscrews 133. Further, on the inner surface of the yoke 10, a scale plate 134 is provided on the set screw 1 in correspondence with the bolt 80.
35 and a long hole 136 so that the height can be adjusted. On the surface of this scale plate 134 are numbers "0" and "100" indicating when the control valve 9 is fully closed and fully open.
is displayed.

Next, the operation of the electric valve operating device 1 having such a configuration will be explained. Note that the explanation assumes that a three-way valve is operated.

When the electric motor 2 stops and the lower seat ring of the control valve 9 is fully closed, the movable body 5 stops at the lowest position and the pointer, that is, the tip of the bolt 80, reaches the number “0” on the scale plate 134. Instructing. At this time,
As shown in FIG. 6, a slight gap G ₁ is created between the lower spring receiver 69B and the stopper 71, and the buffer spring 68 is compressed by this gap G ₁ more than the amount of compression when installed, and the valve stem is A spring load is applied downward to 12. In this case, the upper spring receiver 69
A is press-locked to a step 88 provided inside the outer cylinder 57 by the force of the buffer spring 68, and creates a gap G ₂ between it and the retaining ring 70 that is equal to the gap G ₁ .

In this state, the electric motor 2 is energized,
When the output shaft 15 is rotated in the forward direction, this rotation is reduced by a predetermined reduction ratio by the worm 30 and the worm wheel 31, and is transmitted to the lead screw 4. When the lead screw 4 rotates, the movable body 5 equipped with the lead nut 65 screwed thereon gradually rises and pulls up the valve shaft 12 connected to the connecting bolt 77. That is, the rotational motion of the output shaft 15 is decelerated by the reduction gear mechanism 3, converted into linear motion by the linear motion mechanism 6 made up of the lead screw 4 and the movable body 5, and then transmitted to the valve shaft 12. move it. The relationship between the amount of rotation and the amount of movement of the valve stem 12 at this time shows extremely good linear characteristics.

When the movable body 5 rises, the male threaded portion 66 of the lead screw 4 falls relatively, so it enters the oil tank 61 as shown in FIG. It will be done. When the movable body 5 further rises and reaches the highest position, the lower seat ring of the control valve 9 is fully opened and the pointer 80 moves toward the scale plate 1.
34 number "100" and switch mechanism 10
0 microswitch 104 (see FIG. 4) is closed by cam surface 113, stopping electric motor 2. In this case, since the movable body 5 stops at a position where the upper seat ring of the control valve 9 is still raised by a predetermined amount after the upper seat ring is fully closed, a stopper 71 fixed to the lower end opening of the outer cylinder 57 is moved as shown in FIG. Push up the lower spring receiver 69B as shown. On the other hand, since the retaining ring 70 is fitted onto the outer periphery of the cylinder 58 which is movable relative to the outer cylinder 57, the outer cylinder 57 moves upward and the stepped portion 88 is positioned above the retaining ring 70. As a result, the upper spring receiver 69A is changed to the stepped portion 88 and locked, and the buffer spring 68 is compressed by a predetermined amount more than the compression amount at the time of installation, similar to when the lower seat ring is fully closed. Therefore, even when the upper seat ring is fully closed, the spring load by the buffer spring 68 can be applied upward to the valve stem 12.

Thus, according to the electric valve operating device 1 having the above configuration, when the movable body 5 moves upward with a long stroke, the male threaded portion 66 of the lead screw 4 absorbs the lubricant 6.
Since the lubricant 67 can be supplied to the male threaded portion 66 and the threaded hole 65A of the lead nut 65, the rotational motion of the lead screw 4 can be smoothly transmitted to the movable body 5 with low friction torque. , the lead screw 4 and the lead nut 65 can be prevented from being worn out, rusted, etc. Therefore, the durability of the electric valve operating device 1 itself can be improved, and the lubricant 67 adhering to the male threaded portion 66 of the lead screw 4 and the threaded hole 65A of the lead nut 65 is removed during short stroke movements of the movable body 5 and Since the lubricant 67 is collected dropwise into the oil tank 61 when the lubricant 67 is stopped, it is possible to maintain the lubricant 67 for many years. In addition, since the buffer spring 68 is provided, the valve closing force can be reliably applied to the buffer spring 68 regardless of whether the valve is a 2-way valve or a 3-way valve.
Since the buffer spring 68 acts as a thrust equivalent to the pre-compression force included in 8 and serves as a buffer mechanism to prevent overload, both the electric valve operating device 1 and the control valve 9 are protected from overload and their lifespan is extended. be able to.

As explained above, the electric valve operating device according to the present invention stores lubricant inside the movable body that is screwed into the reed screw, and is configured so that the reed screw is immersed in the lubricant when driven. The lubricant can be effectively supplied to the threaded portion and the threaded hole of the movable body that is screwed into the threaded portion. Therefore, increase in frictional torque due to lack of oil film, abrasion of the thread surface, rusting, etc. can be prevented, and rotation of the lead screw can be smoothly transmitted to the movable body. Also,
It has a simple structure, can be manufactured at low cost, can efficiently recover lubricant, and has a buffer spring built into the movable body to prevent overload that acts in both the upward and downward directions. It can be used for many years and has great practical effects, such as improving the durability of not only the device itself but also the control valve.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing one embodiment of the electric valve operating device according to the present invention, Fig. 2 is a plan view of the device with the cover removed, Fig. 3 is an enlarged cross-sectional view taken along the line of Fig. 1; 4 is a sectional view taken along the line of FIG. 2, FIG. 5 is a plan view of the stopper, and FIGS. 6 and 7 are diagrams for explaining compression of the buffer spring. 1... Electric valve operating device, 2... Electric motor, 3...
Reduction gear mechanism, 4... Lead screw, 5... Movable body, 6... Linear motion mechanism, 7, 8... Bearing, 9
... Control valve, 12 ... Valve shaft, 15 ... Output shaft, 3
0...Worm, 31...Worm wheel, 6
1...Oil tank, 65...Lead nut, 65A...
Screw hole, 66...Male thread part, 67...Lubricant, 6
8...Buffer spring.

Claims (1)

[Scope of utility model registration request] An electric motor, a worm provided on the output shaft of the electric motor, and a worm wheel that constantly meshes with the worm are rotatably supported, the worm wheel is fixed to one end, and a screw is attached to the outer peripheral surface of the other end. The formed lead screw, a movable body that is connected to the valve shaft of the valve body and simultaneously screwed into the male threaded portion of the lead screw and is moved in the axial direction as the screw rotates, and a movable body that is stored in the movable body. The movable body has a double cylinder structure consisting of an inner and an outer cylinder, and an upper part of the movable body is provided between the two cylinders. ,
The present invention is characterized in that a buffer spring that acts as a buffer in either downward direction is elastically loaded in a compressed state, and the buffer spring is compressed by a predetermined amount more than the amount of compression when installed when the control valve is fully closed or fully opened. Electric valve operating device.