JP3418532B2 - On-site pneumatic instrument - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve positioner used for controlling the operating shaft of a control valve used in various plants such as petrochemical and chemical industries to a position according to an input signal, and a field installation type. The present invention relates to a field-type pneumatic instrument such as an electro-pneumatic converter or a field-type controller.

[0002]

2. Description of the Related Art A valve positioner known as a field-type pneumatic instrument of this type uses a valve shaft position as a detection end to a drive unit in order to always keep the relationship between the instrument signal and the valve shaft position accurate against a disturbance. This is a kind of servo mechanism that adjusts the air pressure of the operating device. That is, the valve positioner converts the input signal (displacement signal) into displacement by the nozzle flapper mechanism,
This is converted into an air pressure signal by a nozzle, taken out, amplified by an air amplifier such as a pilot relay, and transmitted as an output air pressure to an operation device of the valve to drive the valve. Further, the actual operation amount of the valve is fed back by a feedback mechanism so as to be balanced with the force due to the input signal so that the valve can always be controlled accurately (Japanese Patent Laid-Open No. 4-185901, etc.).

FIG. 21 shows a conventional example of such a valve positioner, in which 1 is a valve as a controlled device and 2 is a controlled device.
Is an operating shaft of the valve 1, 3 is an operating device mounted on the upper portion of the valve 1 via a yoke 4, and 5 is a valve positioner of a pressure-proof explosion-proof structure mounted on the yoke 4 of the valve 1 via a bracket or the like.

The valve positioner 5, when used in an explosive gas atmosphere, is obliged to have sufficient explosion-proof performance according to the explosion-proof standard.
Therefore, a structure is adopted in which the entire signal conversion unit is housed in the explosion-proof case 6 formed of a special pressure resistant container. A feedback lever 8 that constitutes a feedback mechanism 7 together with the sensor 11 projects outside the explosion-proof case 6, and the base end of the feedback lever 8 is attached to the rotary shaft 12 of the sensor 11 and the operating shaft 2 of the valve 1. Is connected to the pin 9 through a long hole 10.

Further, the explosion-proof case 6 has a built-in electropneumatic converter 13 which constitutes a signal converter. This electro-pneumatic converter 1
Reference numeral 3 is for converting an input signal I0 (for example, 4 to 20 mA) into a displacement of the flapper 22, which is composed of a yoke 17, an exciting coil 18, a permanent magnet 19, a flapper mechanism 20, and the like.

The flapper 22 is swingably supported by a fulcrum spring 24 and constitutes a nozzle flapper mechanism 20 together with the nozzle 23. The flapper 22 is the fulcrum spring 2
When swinging about 4, the flapper 22 and the nozzle 23
When the nozzle back pressure PN changes due to a change in the nozzle gap G, that is, the nozzle gap G, the nozzle back pressure PN is amplified by the pilot relay 26 into the output air pressure Pout, which is then transmitted to the operating device 3. Drives to displace the actuating shaft 2 in the vertical direction, whereby the valve opening of the valve 1 is adjusted. The movement of the actuating shaft 2 is received by the feedback lever 8 and the rotational angle thereof is converted into an electric signal I1 by the sensor 11. The electric signal I1 is fed back to the control calculation unit 25 as a feedback signal to the positioner 5. The input signal I0 is compared with the input signal I0 and fed back to the nozzle flapper mechanism 20 so that the difference becomes zero, thereby stabilizing the movement of the flapper 22.

Reference numeral 27 is a pipe, 29 is a pressure gauge, 30 is a pressure reducing valve, 31 is a throttle, 32 is a changeover switch for switching between manual and automatic, 33 is a span adjusting switch, 34 is a span adjusting screw, and 35 is a span adjusting screw. Is an adjustment switch, 36 is a zero adjustment screw, 37 is a terminal block, and 38 is the nozzle flapper mechanism 2.
It is a cover that covers 0 and the pilot relay 26.

[0008]

Most of the instruments that use air pressure as a working source, including the above-mentioned valve positioner 5 as a field-type pneumatic instrument, need to release the air pressure after use to the atmosphere. An air hole for discharge is provided in a part of the case 6 or the cover 38 constituting the device. In such a pneumatic instrument, for a field instrument that is installed outdoors, it is necessary to take measures to prevent rainwater and the like from entering through the air holes described above.

As a preventive structure for preventing infiltration of rainwater or the like from an air hole provided in a part of the instrument cover 38,
For example, the one disclosed in Japanese Utility Model Laid-Open No. 62-28118 has been already proposed. In this conventional example, the waterproof cover 3 provided with an atmosphere communication window while covering the pilot relay 26 with an appropriate gap from the outer wall of the pilot relay 26 is provided.
Regardless of the mounting posture of the instrument case 6, 8 can be rotatably mounted so that the atmosphere communication window faces downward.

In the above-mentioned valve positioner 5 as a field-type pneumatic instrument, the air hole (atmosphere communicating hole) of the instrument cover or the like is formed so as to face downward as much as possible when the mounting posture is fixed. However, depending on the situation at the installation site, for example, the installation posture of the valve 1 and the piping condition thereof, such a valve positioner 5 may change the mounting direction to any of the up, down, left, and right rotation directions. In such a case, it is necessary to once attach the positioner 5 on site and then reattach the instrument cover 38 so that the air holes face downward, which is a troublesome work.

In particular, in the above-mentioned valve positioner 5, the pilot relay 26 discharges a large amount of air, and this discharge speed determines the valve operating speed. Therefore, discharging from the air hole provided in the instrument cover 38 covering the pilot relay 26 is important from the viewpoint of operating performance, and it is necessary to form a large hole that does not resist the flow of air. Moreover, it is necessary for rainwater to not enter through this hole in order to secure the internal valve performance.

Such a problem similarly occurs in various instruments known as field-type pneumatic instruments as long as the instrument has a mechanism for taking in air from the outside of the instrument or a mechanism for discharging air to the outside of the instrument. However, it is desired to take some measures capable of solving such a problem.

The present invention has been made in view of the above circumstances, and can realize a waterproof structure in which rainwater is unlikely to enter the inside of the instrument cover from the outside regardless of the installation posture of the instrument. The purpose is to obtain a type pneumatic instrument.

[0014]

In order to meet such an object, a field type pneumatic instrument according to the present invention comprises a mechanism for taking in air from the outside of the instrument or a mechanism for discharging air to the outside of the instrument. A field type pneumatic instrument in which the mechanism is covered by a case, a cover and a waterproof cap, wherein the cover has an air circulation hole, and a trumpet-shaped waterproof wall is projected outward at an opening of the air circulation hole. The waterproof cap is combined with the cover so as to cover the air circulation hole having the trumpet-shaped waterproof wall of the cover, and a plurality of air circulation windows are formed on the outer side wall of the waterproof cap. An inner side wall is provided inside the side wall at a predetermined interval to cover the air circulation hole of the cover, and a plurality of air circulation windows are formed in the inner side wall. The distribution window, in which is arranged to avoid a straight line connecting the air circulation window of each outer side wall of the air distribution hole and the waterproof cap of the cover.

The field type pneumatic instrument according to the present invention is
A communication hole is provided in the ceiling surface of the waterproof cap between the outer side wall and the inner side wall of the waterproof cap. Further, in the field-type air measuring instrument according to the present invention, the height of the air flow window on the outer side wall of the waterproof cap is substantially equal to the height of the ceiling surface of the cap and the height of the air flow window on the inner side wall. And the height of the air flow window of the inner side wall is lower than that of the trumpet-shaped waterproof wall of the cover.

According to the present invention, the trumpet-shaped waterproof wall at the opening of the air circulation hole of the cover and the air circulation window of the waterproof cap covering the trumpet-shaped waterproof wall are provided at different positions, respectively. Regardless of the situation, it is possible to prevent rainwater from entering the cover from the outside.

Further, according to the present invention, even when the waterproof cap side is located downward due to the installation posture of the field type pneumatic instrument, water can be discharged from one air flow window or the communication hole formed in the cap ceiling surface. Even if it intrudes, water will escape from the other air circulation windows or communication holes, so that water will not collect in the waterproof cap. Further, according to the present invention, even when the waterproof cap side is located downward due to the installation posture of the field-type pneumatic instrument, the air flow window formed by increasing the height to the ceiling surface on the outer side wall makes it waterproof. The problem that water accumulates in the cap can be solved, and the waterproof effect can be further enhanced.

[0018]

1 to 15 show one embodiment in which a field-type pneumatic instrument according to the present invention is applied to a valve positioner. In these figures, the same as FIG. 21 described above is shown. Alternatively, the corresponding parts are designated by the same reference numerals and the description thereof is omitted.

In these figures, the explosion-proof case 6 is formed in a bottomed cylindrical shape with its front face opened, and a lid 60 is screwed into an opening on the front face side through an O-ring 61 so that a predetermined explosion-proof case can be obtained. And it is airtightly closed while keeping the depth of love. The interior of the explosion-proof case 6 is divided into two front and rear chambers by the terminal block 37, that is, a connection chamber 63 and an electric chamber 64 (FIG. 11).
External wiring (not shown) is inserted into the front side wiring chamber 63 from a cylindrical external wiring connecting portion 66 provided on the peripheral wall of the explosion-proof case 6, and the terminal 67 of the terminal block 37 (see FIG. 9,
11). Two external wiring connection portions 66 are integrally provided on the outer periphery of the explosion-proof case 6 with a 90 ° phase shift in the circumferential direction, and either one is selectively used depending on the mounting direction of the valve positioner 5 to the valve. It The unused side is hermetically closed by the cap 62 (FIG. 11).

On the other hand, the sensor 11 of the feedback mechanism 7, the electropneumatic converter 13 and the printed wiring board 65 are housed in the electric chamber 64. Further, the pressure of the supply air pressure Psup and the output air pressure Po are provided on the outer peripheral wall of the explosion-proof case 6.
Two pressure gauges 29 indicating ut are attached, and a nozzle flapper mechanism 20 and a pilot relay 26 are attached on the back side. And such an explosion-proof case 6
Is fixed to a mounting plate 68 by a plurality of bolts and nuts, and the mounting plate 68 is positioned on the yoke 4 of the valve and mounted by a plurality of bolts 69 (FIG. 5).

The feedback mechanism 7 is, as shown in FIG. 11, a feedback lever 8 provided outside the explosion-proof case 6 and a rotation angle of the feedback lever 8 incorporated in the explosion-proof case 6 converted into an electric signal. The rotary type sensor 11 is provided.

The feedback lever 8 is composed of first and second levers 8A and 8B divided in the longitudinal direction as shown in FIGS. A base end of the first lever 8A is fitted to the rotary shaft 12 of the sensor 11 and fixed by a bolt 70, so that a front end of the first lever 8A projects laterally of the explosion-proof case 6.

The second lever 8B is the first lever 8A.
It is formed to be longer, and the base end portion is the first lever 8
It has a long hole 10 which is detachably attached to the front surface of A by two screws 71 and through which a connecting pin 9 protruding from the operating shaft 2 of the valve is inserted. Feedback lever 8 to 2
The reason why it is composed of the divided first and second levers 8A and 8B is that when the valve positioner 5 is packed, the second lever 8
This is because B is removed from the first lever 8A and packed to reduce the packing volume, reduce the packing cost, and improve the transportability.

The elongated hole 10 is formed to be long in the longitudinal direction of the second lever 8B, and a round hole 72 having a width larger than the width of the elongated hole 10 is continuously provided at the end portion on the valve side. Such a round hole 72
Is provided, it is effective when a pin having a large diameter portion at the tip, such as a bolt, is used as the connecting pin 9 and its head cannot be directly inserted into the elongated hole 10. The long hole 10 has a width of 6.8 mm, the connecting pin 9 has an outer diameter of about 6 mm, and the round hole 72 has a hole diameter of about 10 mm.

A pin pressing spring 73 for pressing the connecting pin 9 against the upper side wall 10a of the elongated hole 10 is mounted on the second lever 8B. This pin pressing spring 73
Is a wire spring, both ends thereof are bent in a U shape, one bent portion 73a is locked from above toward the base of the second lever 8B, and the other bent portion 73b is bent to the second lever 8B.
It is inserted and locked in a small hole 75 provided at the tip of the. The center portion of the pin pressing spring 73, that is, the bent portion 73
The spring portion between a and 73b is curved so as to be convex upward, and forms a pressing portion 73c against the connecting pin 9.

When the pressing portion 73c is curved in a convex shape in this manner, the connecting pin 9 is formed in a linear shape regardless of the position, and compared with the case of the conventional device in which the connecting pin 9 is obliquely attached to the elongated hole 10. Thus, the pressing force on the connecting pin 9 can be made substantially constant. The two screws 71 are provided on the feedback lever 8 in order to reduce an angular error of the second lever 8B due to a clearance between the screw 71 and the screw hole when the second lever 8B is attached to the first lever 8A. Spaced in the longitudinal direction.

A sensor housing 80 for housing the sensor 11 is formed at the rear end of one side surface of the explosion-proof case 6. As shown in FIG. 10 and FIG. 11, the sensor housing portion 80 has a semi-arcuate outer wall 81 provided on the peripheral wall portion of the explosion-proof case 6 and projecting outwardly, and the inside of the case facing the outer wall 81. The sensor 11 is formed in a cylindrical shape that communicates with the inside and outside of the explosion-proof case 6 by the outer wall 81 and an arc-shaped inner wall 82 that is convexly curved with the same radius of curvature in the opposite direction. It is fitted. In this case, between the outer peripheral surface of the sensor 11 and the inner peripheral surface of the sensor accommodating portion 80, a predetermined explosion-proof ski d (example: d = 0.1 m) is provided in accordance with the explosion-proof standard so that flame does not escape to the outside of the case.
m) and the depth L of the gap (example: L = 9 mm). The opening of the sensor housing 80, which is open to the outside of the case, is airtightly closed by attaching the lid member 84 via the gasket 85.

The rotary shaft 10 of the sensor 11 is provided with the lid member 8
The through hole 86 provided in the No. 4 is penetrated through the seal member 87, and the feedback lever 8 is attached to the protruding end portion thereof. In addition, the sensor storage portion 80 has an inner wall 8
Since the length of the second case in the front-back direction is shorter than that of the outer wall 81, the second case communicates with the electric chamber 64 of the explosion-proof case 6. An appropriate gap is provided between the back wall 89 of the sensor housing portion 80 and the back surface of the sensor 11, and the lead wire 90 of the sensor 11 is guided into the electric chamber 64 through the gap and the printed wiring board 6 is provided.
5 (65A) is electrically connected via connector jacks 91A and 91B. In this way, the explosion-proof case 6
By providing the sensor housing 80 that is open to the outside, the sensor 11 can be assembled to the explosion-proof case 6 from the outside of the case with the feedback lever 8 already attached to the rotary shaft 12.

12 to 14, the electropneumatic converter 13 includes a core 17 which is made of a magnetic material to form a magnetic component, an exciting coil 18 and a permanent magnet 19. The core 17 is the exciting coil 1
8, a horizontal core portion 17a to which 8 is attached, left and right vertical core portions 17b provided at both ends of the horizontal core portion 17a,
It is composed of a U-shaped base portion 17A composed of 17c and two open portion forming members 100 and 101 which are cantilevered and attached to the tips of the vertical core portions 17b and 17c, respectively. The vertical core portion 17a is located inside the explosion-proof case 6, and the exciting coil 18 is attached to the vertical core portion 17a.

The vertical core portions 17b and 17c penetrate the rear wall of the explosion-proof case 6 and project to the outside. The projecting end surfaces of the vertical core portions 17b and 17c are horizontally cantilevered so that the open portion forming members 100 and 101 face each other. The screws 102 are detachably attached. The opening forming member 1
00 and 101 are horizontal core portions 17a and vertical core portions 17
b, 17c made of the same magnetic material as a plate,
A magnet unit 105 is formed together with a flapper 22 of a nozzle flapper mechanism 20 described later. The vertical core portions 17b and 17c are provided by insert molding or the like at the same time when the explosion-proof case 6 is formed and penetrate the case wall surface.

The flapper 22 is composed of two movable iron pieces 2 in front and rear facing each other with the open portion forming members 100 and 101 interposed therebetween.
2A, 22B and these movable iron pieces 22A, 2B
A seesaw structure 103 having a symmetrical shape in the front-rear direction is formed with a fulcrum spring 24 that swingably supports 2B. The front-back symmetric shape means a shape that, when the seesaw structure 103 is used upside down, only the polarities of the permanent magnets 19 are reversed and the flapper 22 does not operate in any other way except that the polarity is reversed. To do.

The movable iron pieces 22A and 22B, the open portion forming members 100 and 101, and the yoke 106 of the permanent magnet 19.
Appropriate gaps a, b, c, d, e and f are respectively formed between and. The fulcrum spring 24 is made of a thin leaf spring, is located in the space 107 formed between the facing surfaces of the opening forming members 100 and 101, and both ends thereof are molded with the molding resin 108. In addition, the fulcrum spring 24
A narrow portion 110 is provided near both ends of the mold resin 108, and the flapper 22 can be swung by elastic deformation of the narrow portion 110 in the twisting direction. The movable iron pieces 22A and 22B are attached to the front and back surfaces of the fulcrum spring 24 via spacers 111, respectively.

The mold resin 108 is formed in a disc shape, and the open portion forming members 100 and 101 and the permanent magnet 1 are formed.
9, the fulcrum spring 24 and the yoke 106 are molded by insert molding to form the magnet unit 105. However, the permanent magnet 19 and the yoke 106 may be attached later. In short, the open portion forming members 100 and 101, the permanent magnet 19, the fulcrum spring 24, and the yoke 106 may be unitized to form the magnet unit 105. Two permanent magnets 19 are used, and the N pole is located on the rear side of the case in the two recesses provided on the outer periphery of the mold resin 108 with 180 ° different phases to each other.
The poles are attached to the front side of the case, and are magnetically coupled by the yoke 106.

The magnetic flux of the permanent magnet 19 passes from the N pole through the N pole of the yoke 106-the gap e and is branched into two in the movable iron piece 22A to form gaps a and c-opening portion forming members 100 and 32-gap, respectively. Moving iron piece 3 through b and d
When it enters 6, it merges again and returns to the S pole of the permanent magnet 19 through the S pole of the gap f-yoke 106. When the magnetic flux of the exciting coil 8 passes from the horizontal core portion 17a, the vertical core portion 17b, and the open portion forming member 100, the magnetic flux is branched into two and passes through the gaps a and b-movable iron pieces 22A and 22B, respectively.
After passing through the gaps c and d and passing through the opening forming member 101, they merge again to pass through the vertical core 17c and the horizontal core 17a.
Return to.

Thus, the two movable iron pieces 22A and 22B are
In the electropneumatic converter 13 arranged so as to face each other with the open portion forming members 100 and 101 interposed therebetween, the exciting coil 18 and the permanent magnet 19 are provided in the four gaps a, b, c and d.
Magnetic fluxes of are respectively superposed. In this case, the gap b,
In c, the directions of the magnetic flux are the same, so that the magnetic fluxes are added to increase the attractive force to the flapper 22, and in the gaps a and d, the directions of the magnetic flux are reversed, which are offset and the attractive force decreases.
The difference between these suction forces becomes the rotation torque T for swinging the flapper 22.

Further, guide plates 113 and 114 are detachably attached to both surfaces of the mold resin 108 by screws 115. The nozzle 23 is attached to one end of the rear guide plate 113 so as to closely face and face the movable iron piece 22A. This nozzle 23 is an air nozzle, and an adjusting screw 117 is provided at the tip of the O-ring 11.
It is mounted so as to be able to move back and forth through 8. When the adjusting screw 117 is turned by hand, the adjusting screw 117 moves the movable iron piece 22.
The nozzle gap G is adjusted by the movement adjustment in the direction of approaching and separating from A. The supply air pressure Psup supplied to the nozzle 23 is injected into the movable iron piece 22A through the passage 119 provided in the adjusting screw 117. Therefore, the tip portion of the adjusting screw 117 substantially functions as a nozzle. The adjusting screw 117 is attached to the guide plate 113 by screwing. The guide plates 113 and 114 are temporarily removed from the mold resin 108 when the magnet unit 105 is turned upside down.

The reason why the magnet unit 105 is detachably and reversibly attached by the screw 102 to the projecting end of the yoke body 17A that projects to the outside of the explosion-proof case 6 is that the electropneumatic converter 13 is of the positive operation type ( This is for facilitating the switching when it is used as the electric signal becomes large and the air pressure signal becomes large and when it is used as the reverse operation type (when the electric signal becomes large, the air pressure signal becomes small). In other words, if there is a change that controls the valve that has been operated so far and the valve that operates in reverse, or if there is a failure in the positioner and it is necessary to replace it with a spare positioner, the spare positioner and valve must be replaced. If the operation is different, all that is required is to reverse the magnet unit 105 and reverse the polarity of the permanent magnet 19,
Change work can be performed easily and quickly.

Further, the flapper 22 and the fulcrum spring 24 are unitized to form a seesaw structure 103, and the seesaw structure 103, the permanent magnet 19, the yoke 106, and the space forming members 100 and 101 are unitized to form a magnet unit 105. Therefore, when replacing parts, it is only necessary to replace the whole unit, and it can be installed with high precision, easy to install and adjust, strong against vibration, shock, etc., and earthquake resistance can be improved. . Further, since the fulcrum spring 24 is formed of a leaf spring and the flapper 22 is swingably supported by utilizing elastic deformation in the torsional direction, it is not necessary to urge the coil spring as in the conventional device. Even from the point of view, it is strong against vibrations and shocks, and the fulcrum portion does not wear, so that stable accuracy can be secured for a long period of time.

The nozzle 23 and the adjusting screw 117 are provided on a mounting base 121 as shown in FIG. 15, and a pilot relay 26 for amplifying the back pressure of the nozzle 23 is mounted on the back side of the mounting base 121 via a gasket 123. And flapper mechanism 20, mounting base 121 and pilot relay 2
6 is covered by a cup-shaped cover 122. The mounting base 121 includes a pilot relay 26 and a nozzle 23.
An air circuit 124 for connecting the above is formed. Therefore, it is not necessary to connect the nozzle 23 and the pilot relay 26 by piping, and the assembling work is easy. Further, since the distance between these two parts can be minimized, the responsiveness is also good. Further, as shown in FIG. 4, an open portion 125 is formed on both side surfaces, and when a finger is inserted into the open portion 125, the adjusting screw 117 can be rotated.

The pilot relay 26 is shown in FIG.
Since a conventionally known bleed type that exhausts the consumed air shown in 1 to the outside is used, the description of the detailed configuration thereof will be omitted. A bleed hole 126 is formed on the side surface of the pilot relay 26, and the air exhausted from the bleed hole 126 is provided in the cover 122 through the exhaust port 1.
28 and the waterproof cap 130 attached to the cover 122
The air is exhausted to the outside from the opening 131.

The exhaust port 128 is opened at the center of the back surface of the cover 122, and the opening edge thereof is substantially U outward in the radial direction.
A trumpet-like rainwater intrusion prevention portion 133 as a trumpet-like waterproof wall folded back in a letter shape is provided integrally with the cover 122.

The waterproof cap 130 is formed in a shallow cylindrical shape as shown in FIGS. 1, 2 and 4, so that a cylindrical outer peripheral wall (outer side wall) 130a and the outer peripheral wall 13 are formed.
The first and second annular walls (inner side walls) 130c and 130d are formed integrally with each other and are formed in a concentric circular shape. Outer peripheral wall 130a and first and second annular walls 130c, 1
In a part of 30d, a plurality of openings 131, 135, 136 are formed as air circulation windows at appropriate intervals in the circumferential direction. Here, the openings 131,
The 135 and 136 are formed at different positions in the circumferential direction. In particular, the air flow window 136 of the inner side wall 130d is formed in the air flow hole 128 of the cover 122 and the waterproof cap 13.
It is arranged avoiding the straight line connecting the outer side wall 130a of 0 with the air flow window 131.

Therefore, the air discharged from the bleed hole 126 passes through the openings 135-136 and is discharged from the opening 131 to the outside of the cap 130. Opening 1
31 and the opening 135 are formed at positions that face each other in the radial direction of the cap 130, and the opening 136 is the adjacent opening 1.
It is formed so as to be located between 31 (135). Such a cap 130 has two screw mounting holes 138 formed near the outer circumference of the disc portion 130b, and screws 139 inserted into these screw mounting holes 138 (FIGS. 3 and 7).
Is attached to the cover 122 to cover the bleed hole 128.

When the trumpet-like rainwater intrusion prevention portion 133 is provided on the cover 122 and the openings 131, 135, 135 are further provided on the waterproof cap 130, the angle of attachment of the valve positioner 5 to the valve is determined. However, it is possible to reliably prevent rainwater from entering the cover 122. Further, even if rainwater enters the cap 130, it can be quickly drained from the opening 131 located below.

According to such a structure, rainwater or the like is unlikely to enter the inside of the cover 122 from the outside, regardless of the position of the positioner 5 as the measuring instrument.
There is no need to change the installation, which was required for waterproofing.

9 and 11, the terminal block 37 is formed of a synthetic resin in a disk shape having an outer diameter slightly smaller than the inner diameter on the front end side of the explosion-proof case 6, and the terminal block 37 is opened from the front-side opening of the explosion-proof case 6. By fitting and fixing with a plurality of screws 140 and clips 148, the inside of the case is partitioned into a connection chamber 63 and an electric chamber 64 as described above. The terminals 67 are arranged on the front surface side of the terminal block 37, and a plurality of board mounting portions 145 each formed of a cylindrical body are integrally projectingly provided near the outer periphery of the back surface.
A printed wiring board 65 is attached to.

The printed wiring boards 65 are arranged at appropriate intervals in the front-rear direction and have different sizes.
And printed wiring boards 65A and 65B. The first printed wiring board 65A is slightly smaller than the outer diameter of the terminal block 37, is fitted to the board mounting portion 145, and is fixed to the back surface of the terminal block 37. The first printed wiring board 65A is connected to an external cord through the terminal 67 of the terminal block 37, and a lightning strike protection circuit is formed.

The second printed wiring board 65B is the electric chamber 6
It is smaller than the inner diameter of 4 and is fixed to the tip end surface of the board mounting portion 145 by a screw 146. On the second printed wiring board 65B, an electric circuit that constitutes the control calculation unit 25 (see FIG. 21) and an oscillation circuit for transmitting the opening degree of the valve to an external device are formed. Bowl 1
3 excitation coil 18, sensor 1 of feedback mechanism 7
By connecting 1 and the like, the electric signal I0 is sent to the electropneumatic converter 13, while the feedback signal from the sensor 11 is input. Further, the second printed wiring board 65B has the pins 154 and the connector 155 which form a connector jack, and thus the first printed wiring board 65B.
It is electrically connected to A, whereby a signal of the valve opening degree by the transmission circuit is transmitted to the outside via the first printed wiring board 65A.

Needless to say, the present invention is not limited to the structures described in the above-mentioned embodiments, and the shapes and structures of the respective parts can be appropriately modified and changed. For example, in the above-described embodiment, the waterproof cap 130 includes the outer peripheral wall 130a as the outer side wall and the concentric first and second annular walls 13 as the inner side wall facing the outer peripheral wall 130a at a predetermined interval.
0c, 130d are formed, and openings 131, 135, 136 which are air circulation windows are formed at different positions, but the inner side wall is formed by one annular wall 130d as shown in FIG. 16, for example. But it's okay.

Further, a communication hole 137 may be provided in the waterproof cap ceiling surface 130b between the outer side wall 130a and the inner side wall 130d of the above-mentioned waterproof cap 130 as shown in FIGS. If such a structure is adopted, the positioner 5 may be installed on the waterproof cap 130 side as shown in FIG. 18, but at this time, in the structure according to the above-described embodiment, the outer side wall 130a is disposed. , An air flow window 131 of the inner side wall 130d,
Depending on the height of the cap ceiling surface 130b of the cap 135, it may be unavoidable that rainwater collects in the cap 130, but such a problem can be solved by the existence of the drainage communication hole 137 described above. it can.

Even if such a structure is adopted, even if water enters from one air circulation window 131 or the communication hole 137, the water will escape from the other air circulation window 131 or the communication hole 137. Water will not collect in the cap 130. For example, in such a structure, when the communication hole 137 is installed upward, rainwater and the like enter the cap 130, which is the air circulation window 131.
Is reliably drained from. Further, when installed sideways, rainwater or the like entering from one communication hole 131 is drained from another air circulation window 131 or the above communication hole 137.

Further, as shown in FIG. 19, the air flow window 131 on the outer side wall 130a of the waterproof cap 130 described above.
Is notched to the same level as the inner surface of the ceiling part 130b of the cap 130, and the height of the air flow window 135 of the inner side wall 130d higher than this is
It is also clear that even if the cover 122 is made lower than the trumpet-shaped waterproof wall 133, substantially the same action and effect as in the case of the communication hole 137 can be obtained.

That is, with such a structure, even if the waterproof cap 130 side is located downward due to the installation posture of the positioner 5, water may accumulate in the waterproof cap 130 as shown in FIG. Instead, the water can be surely drained from the air circulation window 131 of the outer side wall 130a, and the waterproof effect can be further enhanced.

In addition, in the above-described embodiment, FIG.
As shown in FIG. 0, when the positioner 5 is mounted sideways, the side walls 130 a, 13 of the waterproof cap 130 are attached.
Even if the height of the 0d air circulation windows 131 and 135 is low, the air flows through the gaps between the respective circulation windows and the cap and the cover 122, bypasses the trumpet-shaped waterproof wall 133, and flows downward.
It is obvious that it will be drained to the outside.

Further, in the above-mentioned embodiment,
For example, as a nozzle flapper mechanism, two movable iron pieces 22
Although an example in which the flapper 22 is formed by A and 22B is shown, the present invention is not limited to this, and may be configured by one flapper as in the conventional nozzle flapper mechanism. This is the same for the other mechanical parts constituting the positioner 5.

Further, although the case where the present invention is applied to the valve positioner 5 has been described in the above-described embodiment, the present invention is not limited to this, and a mechanism for taking air from the outside of the instrument into the inside of the instrument or air to the outside. A mechanism for discharging is provided, and this mechanism is used for the case 6, the cover 122 and the waterproof cap 13.
It is a field type pneumatic instrument covered by 0, as long as it has an air circulation hole in the instrument cover, and it is not limited to a positioner and is applied to various field type pneumatic instruments including an electro-pneumatic converter. can do.

[0057]

As described above, according to the on-site pneumatic instrument according to the present invention, the trumpet-shaped waterproof wall is formed so as to project outward at the opening of the air circulation hole formed in the cover. , A waterproof cap is combined with the cover so as to cover the air circulation hole having the trumpet-shaped waterproof wall of the cover, and a plurality of air circulation windows are formed on an outer side wall of the waterproof cap, which is formed inside the outer side wall. An inner side wall facing the air circulation hole of the cover at a predetermined interval is provided, and a plurality of air circulation windows are further provided on the inner side wall, and the air circulation hole of the cover and the air on each outer side wall of the waterproof cap are provided. Since it was formed avoiding the straight line that connects to the distribution window, it is possible to realize a waterproof structure in which rainwater etc. does not easily infiltrate into the cover from the outside regardless of the installation posture of the instrument, despite the simple configuration. Therefore, according to the present invention, it is not necessary to carry out a troublesome work of changing the attachment for waterproofing which has been conventionally required.

Further, according to the on-site pneumatic instrument according to the present invention, by providing a communication hole on the ceiling surface of the waterproof cap between the outer side wall and the inner side wall of the waterproof cap, one air flow window or communication hole is formed. Even if water invades from the other side, water can be drained from other air circulation windows or communication holes, and even if the instrument is installed with the waterproof cap side facing downward, water will not collect in this waterproof cap. You can

Further, according to the on-site pneumatic instrument according to the present invention, the height of the air flow window on the outer side wall of the waterproof cap is made substantially equal to the height of the ceiling surface of the cap, and the air flow window on the inner side wall of the waterproof cap is increased. By making the height lower than this and lower than the trumpet-like waterproof wall of the cover, even if the waterproof cap side is located downward due to the installation posture of this field type pneumatic instrument, water will not be able to enter the inside of the waterproof cap. It is possible to solve the problem that
The waterproof effect can be further enhanced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part showing one embodiment in which a field-type pneumatic instrument according to the present invention is applied to a positioner.

FIG. 2 is a cross-sectional view of essential parts viewed from a direction different from that of FIG.

FIG. 3 is a plan view of FIG.

4A and 4B are a bottom view and a side sectional view of a waterproof cap characterizing the present invention.

FIG. 5 is a front view showing a state in which a valve positioner to which the present invention is applied is attached to a valve yoke.

FIG. 6 is also a plan view of the positioner.

FIG. 7 is a rear view of the positioner.

FIG. 8 is a left side view of the positioner.

FIG. 9 is a front view of the positioner with the lid body removed.

FIG. 10 is a rear view in which the cover of the positioner is also removed.

11 is a sectional view taken along line XI-XI of FIG.

FIG. 12 is a cross-sectional view showing a mounting structure of an electropneumatic converter.

13 is a sectional view taken along line XIII-XIII in FIG.

14 is a sectional view taken along line XIV-XIV in FIG.

FIG. 15 is a sectional view of an essential part of the positioner.

16 shows a modified example of FIG. 1, and (a) and (b) are a bottom view and a side sectional view of the waterproof cap.

FIG. 17 shows a modification of FIGS. 1 and 16,
(A), (b) is a bottom view and a side sectional view of a waterproof cap.

FIG. 18 is a cross-sectional view of an essential part for explaining a usage example when the waterproof cap of FIG. 17 is used.

FIG. 19 is a cross-sectional view of an essential part showing still another modified example of the positioner with the waterproof cap facing downward.

FIG. 20 is a cross-sectional view of essential parts for explaining the usage state of the waterproof cap when the positioner is in the horizontal position.

FIG. 21 is a schematic configuration diagram showing a conventional example of a positioner.

[Explanation of symbols]

1 ... Valve, 2 ... Operating shaft, 3 ... Operator, 4 ... Yoke, 6
... Explosion-proof case, 7 ... Feedback mechanism, 8 ... Feedback lever, 9 ... Connecting pin, 10 ... Long hole, 11 ... Sensor, 12 ... Rotating shaft, 13 ... Electropneumatic converter, 17 ... Yoke,
18 ... Excitation coil, 19 ... Permanent magnet, 20 ... Nozzle flapper mechanism, 22 ... Flapper, 22A, 22B ... Movable iron piece, 23 ... Nozzle, 26 ... Pilot relay, 37 ... Terminal block, 65 ... Printed wiring board, 80 ... Sensor storage Department,
81 ... Outer wall, 82 ... Inner wall, 84 ... Lid member, 86 ... Insertion hole, 90 ... Lead wire, 121 ... Mounting base, 122 ... Cover, 124 ... Air circuit, 126 ... Bleed hole, 128
... Exhaust port, 130 ... Waterproof cap, 130a, 130
c, 130d ... Side wall, 130b ... Ceiling surface, 131, 13
5, 136 ... Opening (air circulation window) 133 ... Trumpet-like rainwater intrusion prevention part (trumpet-like waterproof wall) 137 ... Communication hole.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-4-185901 (JP, A) JP-A-7-332305 (JP, A) JP-A-8-4708 (JP, A) Actual development Sho-62- 28118 (JP, U) Actual development Sho 53-68255 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01D 11/24

Claims (3)

(57) [Claims] 1. A field-type pneumatic instrument in which a mechanism for taking in air from the outside of the instrument or a mechanism for expelling air from the outside of the instrument is provided inside the instrument, and the mechanism is covered by a case, a cover and a waterproof cap, wherein the cover is provided. Has an air circulation hole, and a trumpet-shaped waterproof wall is formed at an opening of the air circulation hole so as to project outward, and the waterproof cap covers the air circulation hole having the trumpet-shaped waterproof wall of the cover. As described above, the inside of the waterproof cap is formed with a plurality of air circulation windows on the outer side wall thereof, and faces the inner side of the outer side wall at a predetermined interval to cover the air circulation holes of the cover. A side wall is provided, and a plurality of air circulation windows are formed in the inner side wall. The air circulation window of the inner side wall is formed by the air circulation hole of the cover and the air circulation of each outer side wall of the waterproof cap. A field-type pneumatic instrument characterized by being placed avoiding the straight line connecting to the window. 2. The on-site pneumatic instrument according to claim 1, wherein a communication hole is provided on a ceiling surface of the waterproof cap between an outer side wall and an inner side wall of the waterproof cap. . 3. The on-site pneumatic instrument according to claim 1, wherein the height of the air flow window on the outer side wall of the waterproof cap is substantially the same as the ceiling surface of the cap, and the air on the inner side wall is the same. A field-type pneumatic instrument characterized in that the height of the air flow window of the inner side wall is made lower than the height of the flow window, and the height of the air flow window of the inner side wall is made lower than that of the trumpet-shaped waterproof wall of the cover.