JPH0942515A - Electric-pneumatic conversion mechanism of positioner for actuator position controlling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the explosion-proof property, by providing the second arm to interlock a flapper to a rotary shaft at the outer side of the first arm to connect the rotary shaft inserted rotatablly around the axial center in the direction orthogonal to the moving direction of a movable to a housing, to the movable part. SOLUTION: A rod 10 fixed to a diaphragm 9 to partition a diaphragm chamber 6 into an atmospheric chamber 7 and a pressure receiving chamber 8, and projected in the direction of a valve 3 penetrating through the atmospheric chamber 7, is provided. The first lever 12 is supported rotatable in a housing 1 through the first support shaft 11. The tip of the rod 10 is received to the upper end of the first arm 13 extending upward from the support shaft 11. One end of a spring 5 is connected to the upper end of the second arm 14 extending downward from the first support shaft 11 of the first lever 12. By reducing the clearance between a rotary shaft and a hole to the level which can ignor the shaking to allow to rotate the rotary shaft, the explosion-proof property can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-pneumatic conversion mechanism for an actuator position control positioner, and more particularly to an electro-pneumatic conversion mechanism for an actuator position control positioner which has improved explosion proof properties.

[0002]

2. Description of the Related Art For example, as shown in FIG. 3, a conventional actuator position control positioner has a main compressed air supply passage 10 for communicating an actuator with a compressed air source inside.
1 is formed through a valve 102 that opens and closes the main compressed air supply path 101, and a first lever 104 that rotatably supports the valve 102 around a first support shaft 103 (see FIG. 3, an air drive mechanism 105 that is driven to the left, and a spring 108 that drives the valve 102 in one direction via a second lever 107 that is rotatably supported around a second support shaft 106. There is a so-called empty positioner 100, which has a housing 109 with a built-in housing.

The air drive mechanism 105 is a diaphragm chamber.
Pressure receiving chamber 112 formed by partitioning 110 with diaphragm 111
The compressed air having a controlled pressure is supplied to drive the diaphragm 111 in the push side direction (the left direction in FIG. 3), and the rod 113 connected to the diaphragm 111 causes the first lever 10 to move.
The valve 102 connected to the upper end of 4 and the upper end of the first lever 104 is driven in the push side direction.

FIG. 3 shows the pressure receiving chamber 112 of the air drive mechanism 105.
The air-pneumatic positioner 100 is shown in which the actuator is stopped at a predetermined position corresponding to the pressure of the compressed air supplied to the pressure receiving chamber 112 (hereinafter referred to as the input pressure) while the predetermined pressure is supplied to the pressure receiving chamber 112. . This empty positioner 10
At 0, when the input pressure is increased, the inner pressure of the pressure receiving chamber 112 causes the diaphragm 111 (or piston) of the air driving mechanism 105 to push against the spring 108 whose one end is connected to the lower end of the first lever 104. Moving in the direction, valve 10
2 moves in the push side direction. As a result, the upstream side portion 101a of the main compressed air supply passage 101 communicates with the second downstream side portion 101c, and compressed air is supplied to the second pressure receiving chamber of the actuator.

The stem 114 rotates counterclockwise, for example, in conjunction with the operation of an actuator in which compressed air is supplied to the second pressure receiving chamber, and a cam 115 fixed to the stem 114 supports the other end of the spring 108. Second lever 107
Is rotated about the second support shaft 106 in a direction (clockwise direction in the figure) in which the biasing force of the spring 108 is increased. As a result, the spring 108 rotates the first lever 104 about the first support shaft 103 as a center against the internal pressure of the pressure receiving chamber 112 and rotates clockwise in the drawing to move the valve 102 in the pulling side direction (in the drawing). , Right), the valve 102 is returned to the neutral position, the supply of compressed air to the second pressure receiving chamber of the actuator is stopped, and the actuator is stopped at the position corresponding to the increased input pressure. .

When the input pressure is reduced from this state or the state shown in FIG. 3, the diaphragm 111 is pushed in the pulling direction by the urging force of the spring 108, and the valve 102 moves in the pulling direction. As a result, the main compressed air supply passage 10
The upstream portion 101a of 1 is communicated with the first downstream portion 101b, compressed air is supplied to the first pressure receiving chamber of the actuator, and the actuator operates in the opposite direction to when the input pressure is increased.

When the stem 114 and the cam 115 rotate in reverse in conjunction with the reverse operation of the actuator, the second lever 107 supporting the other end of the spring 108 applies the urging force of the spring 108 about the support shaft 106. Rotate in the decreasing direction (counterclockwise direction in the figure) to move the diaphragm 111.
The first lever 104 moves the valve 102 in the pushing direction by the internal pressure of the pressure receiving chamber 112 received by the first lever 104. As a result, the valve 102 is returned to the neutral position, the supply of compressed air to the first pressure receiving chamber of the actuator is stopped, and the actuator is positioned at the position corresponding to the reduced input pressure.

As a method of controlling the pressure of the compressed air supplied to the pressure receiving chamber 112 of the air-pneumatic positioner 100, a method using a so-called electropneumatic conversion mechanism 200 is known. This electro-pneumatic conversion mechanism 200 is, for example, as shown in FIG. 4, a sub-compressed air supply path 201 which communicates with the pressure receiving chamber 112 of the air-pneumatic positioner 100 and a compressed air source, and a relief which communicates the pressure receiving chamber 112 with the atmosphere. Airway 202 and this relief airway 20
The flapper 203 controls the flow rate of 2 to control the internal pressure of the pressure receiving chamber 112, and the electromagnetic drive mechanism 204 that drives the flapper 203.

The flapper 203 is a valve housing 20.
Central passageway 206 that is fixed through 5 and penetrates through the center
And an inlet passage 207 that is formed in the valve housing 205 and connects the auxiliary compressed air supply passage 201 to the central passage 206.
And a nozzle hole 208 as a fixed throttle formed at one end of the central passage 206. Relief airway 20 above
2 is the inlet passage 207, the central passage 206 and the nozzle hole 208.
And an atmosphere communication chamber 210 formed in a cover 209 of the electromagnetic drive mechanism 204, and a communication hole 211 for communicating the atmosphere communication chamber 210 with the atmosphere.

The central passage 206 can be communicated with the atmosphere through the exhaust passage 212, but the exhaust passage 212 is normally closed. The end of the central passage 206 opposite to the nozzle hole 208 is, for example, the ball 2 fitted therein.
Blocked by 13. The electromagnetic drive mechanism 204
Is a cover 209, a permanent magnet 214 disposed inside the cover 209 coaxially with the flapper 203, a yoke 215 for controlling the magnetic field of the permanent magnet 214, and a flapper coil 216.
The flapper 203 is fixed to the bobbin 217 of the flapper coil 216 so as to face the nozzle hole 208. In addition, in the cover 209 of this electromagnetic drive device 204,
The flapper coil 216 is cut off from the atmosphere communication chamber 210, and the flapper 203 and the leaf spring 218 for returning the flapper coil 216 to a predetermined position are provided. When the flapper coil 216 is energized, the flapper 203 is corresponding to the energization amount. Approach the nozzle hole 208 and control the air flow rate out of the nozzle hole 208, which
The internal pressure of the pressure receiving chamber 112 on the upstream side is controlled.

The electromagnetic drive mechanism 204 is configured to drive the flapper coil 216 by electromagnetic action. Instead of this, an electromagnetic drive mechanism configured to drive the movable iron piece by a fixed coil is used. There is also.
Another conventional air-pneumatic positioner 200 shown in FIG. 5 is a first and second main compressed air supply passages 402 and 403 formed in a housing 201 and a first and second main compressed air supply passages 402 and 403 that open and close. 1st and 2nd air supply valve 404a * 404b and the downstream side part 402b * 403b of each main compressed air supply path 402 * 403.
Between the internal pressure and the atmospheric pressure of a hollow cylindrical exhaust valve 406 having an exhaust passage 405 for communicating the air with the atmosphere and a pressure receiving chamber 407 communicating with, for example, the upstream side of the first main compressed air supply passage 402. An air drive mechanism 408 that drives the exhaust valve 406 in the axial direction by pressure, and an auxiliary exhaust valve that is brought into contact with or separated from each end of the exhaust valve 406 in association with the air supply valves 404a and 404b. 409
a.409 b, so that the internal pressure of the pressure receiving chamber 407 can be adjusted by the electropneumatic conversion mechanism 500.

FIG. 5 shows the butterfly valve with the internal pressure of the pressure receiving chamber 407 adjusted by the electropneumatic conversion mechanism 500.
The state in which the actuator 602 that controls the opening / closing degree of the 601 is stopped at a position corresponding to the internal pressure is shown. now,
If the internal pressure of the pressure receiving chamber 407 is increased from this state,
The exhaust valve 406 moves to the right in the figure, and the first auxiliary exhaust valve 409
The exhaust valve 406 is separated from the first main compressed air supply passage 402.
The downstream side portion 402b of the actuator 602 is communicated with the exhaust passage 405 to depressurize the actuator 602, and the actuator 602 moves in the valve closing direction, for example. Also, from this state
When the internal pressure of 407 is decreased, the exhaust valve 406 moves to the left in the figure, the first air supply valve 404 a is opened via the first exhaust auxiliary valve 409 a, and the first exhaust valve 404 a is opened. The main compressed air supply path 402 is opened, compressed air is supplied to the actuator 602,
The actuator 602 moves in the valve opening direction, for example.

The electropneumatic conversion mechanism 500 includes the pressure receiving chamber 407.
A nozzle 502 that communicates with a fixed aperture 501 and a flapper 504 that opens and closes a nozzle hole 503 of the nozzle 502.
And an electromagnetic drive mechanism 505 for driving the flapper 504. The electromagnetic drive mechanism 505 is rotatably supported by a leaf spring 506 at an intermediate portion thereof and has a flapper lever 507 for supporting the flapper 504 at one end and a housing 508. And a feedback mechanism 510.

The torque motor 509 has a housing 508.
The coil 511 and the yoke 512 which are housed inside, and the armature which is rotatably supported by the housing 508 in the middle part through the leaf spring 513 and driven by the coil 511.
514, and the tip of the armature 514 protruding from the housing 508 is received by the end of the flapper lever 507 opposite to the flapper 504.

The feedback mechanism 510 is mounted on the feedback lever 515 linked to the actuator 602, the transmission arm 516, the span adjusting lever 517, and the span adjusting lever 517 and the flapper lever 507. The flapper lever 507 is elastically attached to the armature 514. It is equipped with a feedback spring 518 that allows it. When the first air supply valve 404a is opened, the actuator 602 moves in the valve opening direction, and when the movement in the valve opening direction becomes a predetermined amount or more, the biasing force of the feedback spring 518 is increased. The flapper 504 approaches the nozzle 502, the internal pressure of the pressure receiving chamber 407 is increased, and the exhaust valve 406 moves to the right in the figure. As a result, the opened first air supply valve 404a is closed, and the actuator 602 operating in the opening direction is stopped.

When the downstream side portion 402b of the first main compressed air supply passage 402 is in communication with the atmosphere, the actuator 602 moves in the valve closing direction, and the movement in the valve closing direction is a predetermined amount. When it is above, feedback spring 518
The flapper 504 is separated from the nozzle 502 by decreasing the urging force of the exhaust valve 502, the internal pressure of the pressure receiving chamber 407 decreases, and the exhaust valve 406 moves to the left in the figure. As a result, the exhaust valve 406 is received by the first auxiliary exhaust valve 409a, the downstream side portion 402b of the first main compressed air supply path 402 is shut off from the atmosphere, and the actuator 602 that has been moving in the valve closing direction. Is stopped.

[0017]

By the way, in the case of the conventional electro-pneumatic conversion mechanism 200 shown in FIG. 5, the space where the flapper coils 216 are arranged on both sides of the leaf spring 218 is the atmosphere communication chamber 21.
It is widely opened to 0, and the communication hole 211 for communicating the atmosphere communication chamber 210 with the atmosphere is opened greatly in order to release the compressed air flowing out from the nozzle hole 208 into the atmosphere without any trouble. Therefore, there is a problem that explosion-proof design cannot be performed.

Further, in the case of another conventional electro-pneumatic conversion mechanism 500 shown in FIG. 9, it is necessary to rotate the armature 514. Therefore, an insertion hole formed in the housing 508 to project the armature 514 to the outside of the housing 508. Has to have a large diameter so that a certain amount of play can be secured around the armature 514, which is disadvantageous in enhancing the explosion-proof property.

In view of the above circumstances, it is an object of the present invention to provide a positioner for controlling the position of an actuator, the positioner of which is explosion-proof.

[0020]

SUMMARY OF THE INVENTION The present invention provides a flapper for controlling the input pressure of the air-pneumatic positioner and an electropneumatic conversion mechanism for an actuator position control positioner having an electromagnetic drive mechanism for driving the flapper. The following measures are taken to achieve this.

That is, the electromagnetic drive mechanism is arranged in a housing for accommodating the coil in a hermetically sealed manner, a movable portion that moves forward and backward in the housing by electromagnetic action, and a position eccentric from the center of the movable portion, and is movable in the housing. A rotary shaft that is rotatably inserted around an axis centered in a direction perpendicular to the advancing / retreating direction of the part, a first arm that connects this rotary shaft to the movable part, and a flapper that interlocks with this rotary shaft outside the housing. And a second arm.

According to the present invention, the space in which the flapper is arranged and the interior of the housing are communicated with each other through the gap between the hole formed in the housing and the rotary shaft for inserting the rotary shaft. However, since this gap must be formed so that the rotating shaft can rotate and the wobble of the rotating shaft can be made small enough to be ignored, this gap becomes small enough to be ignored from the viewpoint of explosion proof.

In the present invention, in order to enhance the smoothness and stability of rotation of the rotary shaft, it is possible to support the rotary shaft in the housing by using bearings. In this case, a seal type bearing is used, or a sleeve or spacer that covers the bearing gap is arranged on one side or both sides of the bearing to make the gap formed between the inside and outside of the housing a maze to prevent explosion. It can be narrowed to a negligible level.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An actuator position control positioner according to an embodiment of the present invention will be described below in detail with reference to the drawings. As shown in the configuration diagram of FIG. 1, an actuator position control positioner according to an embodiment of the present invention includes an air-pneumatic positioner P and an electropneumatic conversion mechanism C.
And a main compressed air supply path 2 for communicating an actuator with a compressed air source in the housing 1 of the air-pneumatic positioner P, and the main compressed air supply path 2 is opened and closed. A valve 3 formed of a spool valve, an air drive mechanism 4 for driving the valve 3 and a spring 5 are built in.

The air driving mechanism 4 includes a diaphragm chamber 6
A diaphragm 9 for partitioning the diaphragm chamber 6 into an atmospheric pressure chamber 7 and a pressure receiving chamber 8; and a rod 10 fixed to the diaphragm 9 and penetrating through the atmospheric pressure chamber 7 and protruding toward the valve 3. Prepare In the housing 1, the first
A first lever 12 is rotatably supported via a support shaft 11 of the rod 10, and a tip of the rod 10 is attached to an upper end portion of a first arm 13 extending upward from the first support shaft 11 of the first lever 12. Is accepted. In addition, the first support shaft 11 of the first lever 12
One end of the spring 5 is connected to the upper end of the second arm 14 extending downward from the second arm 14.

A second lever 16 is rotatably supported in the housing 1 via a second support shaft 15.
The other end of the spring 5 is connected to the lower end of the first arm 17 extending downward from the second support shaft 15 of the lever 16 of the lever 16, and extends leftward from the second support shaft 13 of the second lever 16. A cam follower 19 composed of a bearing rotatably supported is provided at the lower end of the second arm 18. Then, the cam follower 19 is received by a cam 21 fixed to a stem 20 that is interlocked with an actuator.

The valve 3 is connected to the upper end of the first arm 13 of the first lever 12, and the pressure receiving chamber 8 of the air drive mechanism 4 is connected.
When the internal pressure of the air-drive mechanism 4 increases or when the urging force of the spring 5 decreases, it moves in the push side direction (the left direction in FIG. 1) and the internal pressure of the pressure receiving chamber 8 of the air drive mechanism 4 decreases, or When the urging force of the spring 5 increases, the spring 5 moves in the pull side direction (the right direction in FIG. 1).

FIG. 1 shows a state in which the actuator is located at a position corresponding to the pressure applied to the pressure receiving chamber 8, and from this state, the pressure receiving chamber 8 of the air drive mechanism 4 is now shown.
Is increased, the diaphragm 9 moves leftward in the figure against the spring 5, the valve 3 moves in the pushing direction (left direction in FIG. 1), and the valve 3 supplies the main compressed air. The upstream portion 2a of the passage 2 communicates with the second downstream portion 2c, and compressed air is supplied to the second pressure receiving chamber of the actuator. As a result, the actuator operates, and the stem 16 and the cam 17 interlocked with this operation rotate counterclockwise in FIG. 1, for example, and the second lever 16 is driven by the cam 21 to rotate clockwise in the drawing. It rotates and increases the biasing force of the spring 5. When the urging force of the spring 5 increases, the first lever 12 rotates clockwise in FIG. 1 to move the valve 3 to the neutral position, so that the upstream side portion 2a of the main compressed air supply passage 2 moves to the first position. And the second downstream portion 2b.2
Cut off from c. Accordingly, the supply of the compressed air to the second pressure receiving chamber of the actuator is stopped, and the operation of the actuator is stopped at a position corresponding to the increased internal pressure of the pressure receiving chamber 8.

If the internal pressure of the pressure receiving chamber 8 of the air drive mechanism 4 is reduced from this state or the state shown in FIG. 1, the spring 5 resists the pressure of the pressure receiving chamber 8 and moves the first lever 12 clockwise. The valve 3 toward the pull side (Fig. 1
(Up, right) to make the upstream portion 2a of the air supply path 2 communicate with the first downstream portion 2b, and compressed air is supplied to the first pressure receiving chamber of the actuator. as a result,
The actuator reversely operates, and the stem 16 and the cam 17 interlocked with the reverse operation rotate clockwise, for example, in FIG. 1, and the second lever 16 is restricted by the cam 21 by the spring 5 and counterclockwise in FIG. Rotate around, spring 5
Reduce the bias of. When the biasing force of the spring 5 decreases, the internal pressure of the pressure receiving chamber 8 resists the biasing force of the spring 5 and rotates the first lever 12 in the counterclockwise direction in FIG. 1 to move the valve 3 to the neutral position. Let As a result, the upstream portion 2a of the main compressed air supply passage 2 is cut off from the first and second downstream portions 2b and 2c, the supply of compressed air to the first pressure receiving chamber of the actuator is stopped, and the operation of the actuator is stopped. Stops at a position corresponding to the reduced internal pressure of the pressure receiving chamber 8.

The electropneumatic conversion mechanism C is a valve housing.
A relief passage 24 is provided in the valve housing 22. The relief passage 24 communicates the pressure receiving chamber 8 with the atmosphere. And this relief road
A nozzle hole 25 as a predetermined fixed throttle is formed in the middle of 24, and a flapper 26 that comes into contact with and separates from the outlet end of the nozzle hole 25 is provided.

The electromagnetic drive mechanism 23 includes a permanent magnet 27, a yoke 28 surrounding the permanent magnet 27, a moving coil 29 arranged coaxially with the permanent magnet 27 and moving back and forth in the axial direction of the permanent magnet 27, and these. And a housing (30) that is housed in a sealed manner. The rotating shaft 31 is rotatably supported by the housing 30 at a position decentered from the shaft centers of the permanent magnet 27 and the moving coil 29, and one end of the rotating shaft 31 is attached to one end of the rotating shaft 31, as shown in the perspective views of FIGS. While fixing the free end of the fixed first arm 32 to the axis of the moving coil 29, the flapper 26 is fixed to the free end of the second arm 33 fixed to the other end of the rotary shaft 31. As a result, the flapper 26 moves in the nozzle hole 25 in association with the movement of the moving coil 29.
It is arranged so as to come in contact with and separate from the exit end of.

The rotary shaft 31 may be directly supported by the housing 30, but in this embodiment, in order to enhance the smoothness and stability of the rotation of the rotary shaft 31, the rotary shaft 31 is improved.
Is rotatably supported by the housing 30 via a pair of bearings 34 and 35. Further, it is preferable to use seal type bearings capable of ensuring explosion proof as both bearings 34 and 35, but in this embodiment, non-seal type bearings 34 and 35 are used, and each bearing between both bearings 34 and 35 is used. A spacer 36 is interposed so as to close a gap for communicating between both ends of 34 and 35, and a passage for communicating between the relief passage 24 and the inside of the housing 30 is made into a labyrinth and made narrow enough to be ignored in the explosion-proof design. In addition, the lead-out hole 42 of the lead wire from the housing 30 is closed by an insulating material that fills the lead-out end portion of the lead wire and a terminal electrically connected thereto, or is closed by using a grommet.

Further, as shown in FIGS. 1 and 2, a washer 37 made of a magnetic material such as iron or steel is supported between the moving coil 29 and the first arm 32, and the permanent magnet 27 and the yoke 28 are supported. By sucking the washer 37, the moving coil 29 is pulled back to the permanent magnet 27 side when not energized, and the excessive movement of the moving coil 29 when energized is suppressed to stabilize the operation of the moving coil 29.

When the moving coil 29 is energized, the moving coil 29 receives a force proportional to the current value and urges the flapper 26 in the opening direction to adjust the opening of the nozzle hole 25. As a result, the flow rate of the compressed air discharged from the nozzle hole 25 is controlled and the internal pressure of the pressure receiving chamber 8 is controlled. In addition,
In this embodiment, the housing 1 of the air-pneumatic positioner P comprises a main body housing 38 and a sub-housing 39 mounted on one side of the main body housing 38.
The diaphragm chamber 6 is formed between the sub housing 38 and the sub housing 39, and the pressure receiving chamber 8 is formed in the sub housing 39 by inserting the diaphragm 9 between the main body housing 38 and the sub housing 39. I am trying.

In the main body housing 38, a part 40a of the sub-compressed air supply passage 40, which is branched from the upstream side portion 2a of the main compressed air supply passage 2 and opens to the sub-housing 39 side.
And a part of the sub compressed air supply passage 40 in the main body housing 38 is formed in the sub housing 39.
The remaining portion 40b of the sub-compressed air supply passage 40 that communicates with the. An orifice 41 is formed in the remaining portion 40b of the sub compressed air supply passage 40, and the main compressed air supply passage 2
The amount of air supplied to the sub-compressed air supply passage 40 when the valve is opened is limited to a certain level or less to prevent the supply pressure of the compressed air to the actuator from dropping below a certain level.

By forming the auxiliary compressed air supply passage 40 in the housing 1 in this way, it is not necessary to assemble a cheese joint or piping to the pressure receiving chamber 8 in the housing 1, and the number of parts can be reduced and The step of assembling the cheese joint and the pipe to the pressure receiving chamber 8 can be omitted, and the cost can be significantly reduced. Further, at the time of transportation, installation, and after installation, there is no possibility that other objects may collide with the cheese joint or the pipe to the pressure receiving chamber 8 and be damaged, and it is possible to prevent the positioner from malfunctioning due to such damage.

In the above embodiment, the electromagnetic drive mechanism 23 is of the moving coil type, but instead of this, of the movable iron piece type, the coil is fixed in the housing and the movable iron piece is driven by this coil. The present invention can be applied to the case where an electromagnetic drive mechanism is used.

[0038]

As described above, the electromagnetic drive mechanism of the actuator position control positioner according to the present invention,
A housing that encloses the coil in a sealed manner, a movable part that advances and retreats by electromagnetic action within the housing, and an eccentric position from the center of the movable part. A rotary shaft that is rotatably inserted around the rotary shaft, a first arm that connects the rotary shaft to the movable portion, and a second arm that links a flapper to the rotary shaft outside the housing are provided. Since the gap that connects the space where the flapper is placed and the inside of the housing communicate with each other is small enough to be ignored from the viewpoint of explosion proof, the effect of increasing explosion proof is obtained, and the configuration is simple and easy. Moreover, the effect that it can be implemented at low cost can be obtained.

Further, in the present invention, in particular, when the rotating shaft is supported by the housing through the bearing and the spacer or the sleeve for covering the space communicating the both ends of the bearing is provided, the gap for communicating the both ends of the bearing is provided. Thus, the smoothness and stability of the rotation of the rotary shaft can be improved without impairing the explosion-proof property, and the control accuracy of the actuator position control positioner can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a perspective view of a main part of the present invention.

FIG. 3 is a configuration diagram of a conventional empty-air positioner.

FIG. 4 is a sectional view of a conventional electropneumatic conversion mechanism.

FIG. 5 is a configuration diagram of another conventional example.

[Explanation of symbols]

 C ... Electro-pneumatic conversion mechanism P ... Pneumatic positioner 23 ... Electromagnetic drive mechanism 26 ... Flapper 29 ... Moving coil 30 ... Housing 31 ... Rotating shaft 32 ... First arm 33 ... Second arm 34/35 ... Bearing 36 ... Spacer

Claims (2)

[Claims] 1. An electropneumatic conversion mechanism of an actuator position control positioner having a flapper for controlling an input pressure of a dry-air positioner and an electromagnetic drive mechanism for driving the flapper, wherein the electromagnetic drive mechanism accommodates a coil in a sealed manner. The housing, the movable part that advances and retreats by electromagnetic action in the housing, and the eccentric position from the center of the movable part. The housing is rotatable around an axis in a direction perpendicular to the moving direction of the movable part. A rotating shaft that is inserted, a first arm that connects the rotating shaft to a movable portion, and a second arm that links a flapper to the rotating shaft outside the housing.
An electropneumatic conversion mechanism for an actuator position control positioner, comprising: 2. The electro-pneumatic conversion mechanism of the actuator position control positioner according to claim 1, wherein the rotary shaft is supported by the housing via a bearing, and a spacer or a sleeve is provided to cover a space communicating both ends of the bearing. .