JPH11118533A - Job site type air instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a simple waterproof structure for preventing invasion of rain water or the like from an air flow hole formed in an instrument cover regardless of a mounting attitude of a job site type air instrument. SOLUTION: The job site type air instrument comprises a mechanism for inputting the air from the atmosphere into the instrument or a mechanism for externally exhausting the air, and a case 6, cover 122 and waterproof cap 130 for covering the mechanism. In this case, the cover 122 has an air flow hole 128, and a flared waterproof wall 133 formed to externally protrude from its air flow hole opening. The cap 130 is coupled to the cover 122 to cover the hole having the wall. A plurality of air flow windows 136 are formed at an outer sidewall 130a of the cap. And, inner sidewalls 130c, 130d opposed at a predetermined interval to the outer sidewall are provided at the inside of the outer sidewall to cover the holes of the cover. A plurality of air flow window 136 are formed except on a straight line for respectively connecting the holes of the cover to the windows of the outer sidewall of the cap.

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 an operating shaft of a control valve used in various plants such as petrochemical and chemical industries to a position corresponding to an input signal, and a field-installed type. The present invention relates to an on-site pneumatic instrument such as an electro-pneumatic converter or an on-site controller.

[0002]

2. Description of the Related Art A valve positioner known as a field type pneumatic instrument of this kind is a valve positioner which uses a valve shaft position as a detection end to a drive unit in order to always keep the relationship between an instrument signal and a valve shaft position accurately against disturbance. This is a kind of servo mechanism that adjusts the air pressure of the actuator. 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, transmitted to a valve operating device as output air pressure, and driven to operate the valve. Further, the actual operation amount of the valve is fed back by a feedback mechanism so as to balance with the force of the input signal, and to always perform accurate control (Japanese Patent Laid-Open No. 4-185901).

FIG. 21 shows a conventional example of such a valve positioner, in which reference numeral 1 denotes a valve as 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 an explosion-proof structure mounted on the yoke 4 of the valve 1 via a bracket or the like.

When used in an explosive gas atmosphere, the valve positioner 5 is required to have sufficient explosion-proof performance according to explosion-proof standards.
For this reason, a structure is employed in which the entire signal conversion unit is housed in an explosion-proof case 6 formed of a special pressure-resistant container. A feedback lever 8, which constitutes a feedback mechanism 7 together with a sensor 11, protrudes outside the explosion-proof case 6. A base end of the feedback lever 8 is attached to a rotation shaft 12 of the sensor 11, and an operation shaft 2 of the valve 1 is provided. Are connected to a pin 9 via a long hole 10.

[0005] The explosion-proof case 6 has a built-in electropneumatic converter 13 constituting a signal converter. This electropneumatic converter 1
Reference numeral 3 denotes a device for converting an input signal I0 (for example, 4 to 20 mA) into a displacement of the flapper 22, and includes 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. Flapper 22 is fulcrum spring 2
4, the flapper 22 and the nozzle 23
When the nozzle back pressure PN changes due to a change in the nozzle back pressure PN and the output air pressure Pout is amplified by the pilot relay 26 and transmitted to the operating device 3, this operating device 3 Drives to displace the operating shaft 2 in the vertical direction, whereby the valve opening of the valve 1 is adjusted. The movement of the operating shaft 2 is received by the feedback lever 8 and its rotation angle is converted into an electric signal I1 by the sensor 11, and the electric signal I1 is fed back as a feedback signal to the control operation unit 25 to the positioner 5. And the feedback 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 adjustment switch, 34 is a span adjustment screw, 35 Is an adjustment switch, 36 is a zero adjustment screw, 37 is a terminal block, 38 is a nozzle flapper mechanism 2
0 and a cover for covering the pilot relay 26.

[0008]

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

As a structure for preventing rainwater or the like from entering through an air hole provided in a part of the instrument cover 38,
For example, Japanese Unexamined Utility Model Publication No. 62-28118 has already been proposed. In this conventional example, the waterproof cover 3 covers the pilot relay 26 while maintaining an appropriate gap from the outer wall of the pilot relay 26 and has an air communication window.
8 can be rotatably mounted so that the air communication window faces downward regardless of the mounting posture of the instrument case 6.

In the above-described valve positioner 5 or the like as a field type pneumatic instrument, when the mounting posture is determined, an air hole (atmosphere communication hole) of an instrument cover or the like is formed so as to face downward as much as possible. However, the mounting direction of such a valve positioner 5 may be changed to one of the up, down, left, and right rotation directions depending on the situation at the installation site, for example, the installation posture of the valve 1 and its piping state. In such a case, it is necessary to mount the positioner 5 once at the site, and then mount the instrument cover 38 again so that the air holes face downward, which is quite troublesome.

Particularly, in the valve positioner 5 described above, the amount of air discharged from the pilot relay 26 is large, and the discharge speed determines the valve operation speed. Therefore, the discharge from the air hole provided in the instrument cover 38 that covers the pilot relay 26 is important from the viewpoint of operation performance, and it is necessary to form a large hole that does not impede the flow of air. Moreover, it is necessary that rainwater or the like does not enter through this hole in order to ensure the internal valve performance.

[0012] Such a problem also arises in various instruments known as field-type pneumatic instruments, as long as the instrument has a mechanism for taking in air from outside the instrument or a mechanism for discharging air to the outside. Therefore, it is desired to take some measure that can solve such a problem.

The present invention has been made in view of such circumstances, and it is possible to realize a waterproof structure in which rainwater or the like 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 pneumatic instrument.

[0014]

SUMMARY OF THE INVENTION In order to meet such an object, a field-type pneumatic instrument according to the present invention is provided with a mechanism for taking in air from outside the instrument or a mechanism for discharging air to the outside inside the instrument. An in-situ pneumatic instrument covering a mechanism with a case, a cover, and a waterproof cap, wherein the cover has an air flow hole, and a trumpet-shaped waterproof wall projects outward at an opening of the air flow hole. The waterproof cap is coupled to the cover so as to cover an air flow hole having a flared waterproof wall of the cover, and a plurality of air flow windows are formed on an outer side wall of the waterproof cap. An inner side wall is provided inside the side wall facing the air flow opening of the cover at a predetermined interval to cover the air flow hole, and a plurality of air flow 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.

[0015] Further, the on-site pneumatic instrument according to the present invention comprises:
A communication hole is provided in a ceiling surface of the waterproof cap between an outer side wall and an inner side wall of the waterproof cap. Further, in the field type pneumatic instrument according to the present invention, the height of the air circulation 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 circulation window on the inner side wall is adjusted. And the height of the air flow window on the inner side wall is made lower than the trumpet-shaped waterproof wall of the cover.

According to the present invention, the installation posture of the instrument is provided by the outer side wall and the inner side wall in which 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 same are provided at different positions. However, it is possible to prevent rainwater or the like from entering the inside of the cover from outside.

Further, according to the present invention, even when the waterproof cap side is located at a lower position depending on the installation posture of the on-site pneumatic instrument, water flows from one air circulation window or a communication hole formed in the cap ceiling surface. Even if the water enters, the water escapes from the other air circulation windows or communication holes, so that water does not accumulate in the waterproof cap. Furthermore, according to the present invention, even when the waterproof cap side is positioned downward due to the installation posture of the on-site pneumatic instrument, the waterproofing is achieved by the air circulation window formed by increasing the height to the ceiling surface on the outer side wall. Problems such as accumulation of water in the cap can be solved, and the waterproof effect can be further enhanced.

[0018]

FIG. 1 to FIG. 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. Or, corresponding parts are denoted by the same reference numerals and description thereof is omitted.

In these figures, the explosion-proof case 6 is formed in a bottomed cylindrical shape whose front face is open, and a cover 60 is screwed into an opening on the front side via an O-ring 61 to provide a predetermined explosion-proof ski. And it is airtightly closed keeping the depth of the ski. The interior of the explosion-proof case 6 has two chambers, namely a connection chamber 63 and an electrical chamber 64 (FIG. 11).
External wiring (not shown) is inserted into the front connection room 63 from a cylindrical external wiring connection portion 66 provided on the peripheral wall of the explosion-proof case 6, and the terminal 67 of the terminal block 37 (FIG.
11). The two external wiring connection portions 66 are integrally provided on the outer periphery of the explosion-proof case 6 with a phase shift of 90 ° in the circumferential direction, and one of them is selectively used depending on the mounting direction of the valve positioner 5 with respect to the valve. You. The unused side is hermetically closed by a cap 62 (FIG. 11).

On the other hand, the electric chamber 64 houses the sensor 11 of the feedback mechanism 7, the electropneumatic converter 13, and the printed wiring board 65. Further, on the outer peripheral wall of the explosion-proof case 6, the pressure of the supply air pressure Psup and the output air pressure Po
Two pressure gauges 29 for displaying ut are mounted, and a nozzle flapper mechanism 20 and a pilot relay 26 are mounted 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 is mounted by a plurality of bolts 69 (FIG. 5).

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

The feedback lever 8 is composed of first and second levers 8A and 8B divided in the longitudinal direction as shown in FIGS. The first lever 8 </ b> A has a proximal end fitted to the rotating shaft 12 of the sensor 11 and is fixed by a bolt 70, so that a distal end protrudes to the side of the explosion-proof case 6.

The second lever 8B is a first lever 8A
The first lever 8 is formed longer than the first lever 8.
A 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
The reason why the first and second levers 8A and 8B are divided is that the second lever 8
By removing B from the first lever 8A and packing it, the packing volume is reduced, so that packing cost is reduced and transportability is improved.

The elongated hole 10 is formed to be long in the longitudinal direction of the second lever 8B, and a round hole 72 larger than the width of the elongated hole 10 is continuously provided at the end on the valve side. Such a round hole 72
Is effective when a pin having a large diameter portion at its 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 width of the long hole 10 is 6.8 mm, the outer diameter of the connecting pin 9 is about 6 mm, and the diameter of the round hole 72 is about 10 mm.

The second lever 8B is provided with a pin pressing spring 73 for pressing the connecting pin 9 against the upper side wall 10a of the elongated hole 10. This pin pressing spring 73
Is made of a wire spring, both ends of which 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 connected to the second lever 8B.
Is inserted and locked in a small hole 75 provided at the distal end of the head. The central 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 protrude 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 straight line regardless of the position, and the pressing portion 73c is mounted obliquely with respect to the long hole 10 as compared with the conventional device. Thus, the pressing force on the connecting pin 9 can be made substantially constant. The two screws 71 are provided to reduce the angle error of the second lever 8B due to the clearance between the screw 71 and the screw hole when the second lever 8B is attached to the first lever 8A. It is spaced apart in the longitudinal direction.

At the rear end of one side of the explosion-proof case 6, a sensor housing 80 for housing the sensor 11 is formed. As shown in FIGS. 10 and 11, the sensor housing portion 80 has a semicircular outer wall 81 provided on the peripheral wall portion of the explosion-proof case 6 and protruding outward, and is provided inside the case in opposition to the outer wall 81. The outer wall 81 is formed in a cylindrical shape communicating with the inside and outside of the explosion-proof case 6 by an arc-shaped inner wall 82 convexly curved with the same radius of curvature in the opposite direction to the outer wall 81. Mated. In this case, a predetermined explosion-proof ski d (for example, d = 0.1 m) is provided between the outer peripheral surface of the sensor 11 and the inner peripheral surface of the sensor housing 80 in accordance with the explosion-proof standard so that the flame does not escape to the outside of the case.
m) and the depth L of the key (e.g., L = 9 mm). The opening of the sensor housing 80 that is open to the outside of the case is hermetically closed by the lid member 84 being attached via a gasket 85.

The rotation shaft 10 of the sensor 11 is
4 penetrates through an insertion hole 86 provided through the seal member 87, and the feedback lever 8 is attached to a protruding end thereof. Further, the sensor housing section 80 is provided on the inner wall 8.
Since the length of the case 2 in the front-rear direction is shorter than the outer wall 81, the case 2 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 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 this gap, and
5 (65A) is electrically connected via connector jacks 91A and 91B. Thus, the explosion-proof case 6
When the sensor housing 80 that opens to the outside is provided, the sensor 11 can be assembled to the explosion-proof case 6 from outside the case with the feedback lever 8 attached to the rotating shaft 12 in advance.

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

The vertical core portions 17b and 17c penetrate through the back wall of the explosion-proof case 6 and protrude to the outside. The protruding end faces are horizontally cantilevered so that the opening forming members 100 and 101 face each other. Each is detachably attached by a screw 102. The opening forming member 1
00 and 101 are a horizontal core part 17a, a vertical core part 17
b and 17c are formed in a plate shape from the same magnetic material,
The magnet unit 105 is formed together with the flapper 22 of the nozzle flapper mechanism 20 described later. The vertical core portions 17b and 17c are provided simultaneously with the formation of the explosion-proof case 6 by insert molding or the like and penetrating through the case wall surface.

The flapper 22 includes two movable iron pieces 2 facing each other with the open portion forming members 100 and 101 interposed therebetween.
2A and 22B.
A seesaw structure 103 having a symmetrical shape in the front-rear direction is formed by the fulcrum spring 24 that supports the 2B swingably. The symmetrical shape means that when the seesaw structure 103 is used upside down, only the polarity of the permanent magnet 19 is reversed and the flapper 22 does not have any other effect except for the reverse operation. I do.

The movable iron pieces 22A, 22B, the opening forming members 100, 101, and the yoke 106 of the permanent magnet 19
Are formed with appropriate gaps a, b, c, d, e, and f, respectively. The fulcrum spring 24 is formed of a thin leaf spring, is located in a space 107 formed between the opposing surfaces of the open portion forming members 100 and 101, and both ends are molded with a molding resin 108. The fulcrum spring 24
A narrow portion 110 is provided in the vicinity of both ends molded with the molding resin 108, and the flapper 22 can swing by elastic deformation of the narrow portion 110 in the torsional 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 disk shape, and the open portion forming members 100 and 101 and the permanent magnet 1 are formed.
9. The magnet unit 105 is formed by molding the fulcrum spring 24 and the yoke 106 by insert molding. However, the permanent magnet 19 and the yoke 106 may be attached later. In short, the opening 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. The two permanent magnets 19 are used, and N poles are provided in two concave portions provided on the outer periphery of the mold resin 108 so as to be out of phase with each other by 180 °.
The poles are mounted so that they are on the front side of the case, and are magnetically coupled by a yoke 106.

The magnetic flux of the permanent magnet 19 passes from the N pole to the N pole of the yoke 106 minus the gap e, and is branched into two at the movable iron piece 22A. Movable iron piece 3 after b and d
6, they merge again and return to the S pole of the permanent magnet 19 via 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 to the vertical core portion 17b and passes through the open portion forming member 100, the magnetic flux is branched into two and passes through the gaps a and b and the movable iron pieces 22A and 22B, respectively.
After passing through the open portion forming member 101 through the gaps c and d, the horizontal core portion 17a merges again through the vertical core portion 17c.
Return to

As described above, the two movable iron pieces 22A and 22B
Are arranged so as to face each other with the opening forming members 100 and 101 interposed therebetween. In the four gaps a, b, c and d, the exciting coil 18 and the permanent magnet 19
Are superimposed on each other. In this case, the gap b,
In the case of c, since the directions of the magnetic fluxes are the same, the magnetic fluxes are added and the attraction force to the flapper 22 increases, and in the gaps a and d, the directions of the magnetic fluxes are reversed so that they are offset and the attraction force decreases.
The difference between these suction forces is 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 be close to and opposed to the movable iron piece 22A. The nozzle 23 is made of an air nozzle, and an adjusting screw 117
8 so that it can move forward and backward. When the adjusting screw 117 is manually turned, the adjusting screw 117 is
The nozzle gap G is adjusted to move toward and away from A, thereby adjusting the nozzle gap G. The supply air pressure Psup supplied to the nozzle 23 is injected into the movable iron piece 22A through a passage 119 provided in the adjusting screw 117. Therefore, the tip of the adjusting screw 117 substantially functions as a nozzle. Such an 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 that the magnet unit 105 is detachably and reversibly turned upside down by screws 102 at the protruding end of the yoke main body 17A which protrudes outside the explosion-proof case 6 is that the electropneumatic converter 13 is of a normal operation type ( This is for facilitating switching when using as an electric signal increases as the air pressure signal increases or as a reverse operation type (as the electric signal increases, the air pressure signal decreases). In other words, if a change is made to control a valve that operates in the opposite direction to the valve that has been controlled up to now, or if a positioner breaks down and it is necessary to replace it with a spare positioner immediately, If the operations are different, it is only necessary to reverse the polarity of the permanent magnet 19 by turning the magnet unit 105 upside down,
The change operation can be performed easily and quickly.

The flapper 22 and the fulcrum spring 24 are unitized to form a seesaw structure 103. 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 sufficient to replace the entire unit, it can be mounted with high accuracy, easy installation and adjustment work, strong against vibration, impact, etc., and it is possible to improve earthquake resistance . In addition, 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, there is no need to urge the flapper 22 with a coil spring as in the conventional device. From the point of view, it is resistant to vibration, impact and the like, and since the fulcrum does not wear, stable accuracy can be ensured for a long period of time.

The nozzle 23 and the adjusting screw 117 are provided on a mounting table 121 as shown in FIG. 15, and a pilot relay 26 for amplifying the back pressure of the nozzle 23 is mounted via a gasket 123 on the back side. And flapper mechanism 20, mounting base 121 and pilot relay 2
6 is covered with a cup-shaped cover 122. The mounting base 121 has a pilot relay 26 and a nozzle 23.
Is formed. Therefore, there is no need to connect the nozzle 23 and the pilot relay 26 by piping, and the assembling work is easy. In addition, since the distance between these two components can be minimized, the responsiveness is good. Further, as shown in FIG. 4, an opening 125 is formed on both side surfaces, and when a finger is inserted into the opening 125, the adjusting screw 117 can be rotated.

As the pilot relay 26, FIG.
Since a conventionally well-known bleed type for exhausting the consumed air shown in FIG. 1 to the outside is used, the detailed configuration thereof will not be described. A bleed hole 126 is formed on a side surface of the pilot relay 26, and air exhausted from the bleed hole 126 is supplied to an exhaust port 1 provided in the cover 122.
28 and a waterproof cap 130 attached to the cover 122
The air is exhausted to the outside through the opening 131.

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

The waterproof cap 130 is formed in a shallow bottom cylindrical shape as shown in FIGS. 1, 2 and 4, so that a cylindrical outer peripheral wall (external side wall) 130a and the outer peripheral wall 13a are formed.
A first and second annular walls (inner side walls) 130c and 130d are formed integrally with each other and protrude integrally therewith. Outer peripheral wall 130a and first and second annular walls 130c, 1
In a part of 30d, a plurality of openings 131, 135, and 136 are formed at appropriate intervals in the circumferential direction as air flow windows. Here, each of the above-mentioned openings 131,
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 connected to the air flow hole 128 of the cover 122 and the waterproof cap 13.
0 is disposed so as not to be on a straight line connecting the outer side wall 130a and the air circulation window 131.

Therefore, the air discharged from the bleed hole 126 passes through the openings 135 to 136 and is exhausted from the opening 131 to the outside of the cap 130. Opening 1
31 and the opening 135 are formed at positions facing each other in the radial direction of the cap 130, and the opening 136 is formed in the adjacent opening 1.
31 (135). Such a cap 130 has two screw mounting holes 138 formed near the outer periphery of the disk portion 130b, and screws 139 inserted into these screw mounting holes 138 (FIGS. 3 and 7).
To cover the bleed hole 128 by being attached to the cover 122.

If the cover 122 is provided with the trumpet-shaped rainwater intrusion prevention portion 133 and the waterproof cap 130 is provided with the openings 131, 135, and 135, the angle at which the valve positioner 5 is attached to the valve is determined. However, it is possible to reliably prevent rainwater from entering the cover 122. 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 an instrument.
The installation change work for waterproofing, which was conventionally required, becomes unnecessary.

9 and 11, the terminal block 37 is formed of a synthetic resin into a disk shape whose outer diameter is slightly smaller than the inner diameter at the front end side of the explosion-proof case 6 and extends from the front opening of the explosion-proof case 6. By being fitted and fixed by 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 side of the terminal block 37, and a plurality of substrate mounting portions 145 formed of a cylindrical body are integrally protruded near the outer periphery of the rear surface.
The printed wiring board 65 is mounted on the second board.

The first and second 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 65 </ b> A 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 via the terminal 67 of the terminal block 37, and has a lightning protection circuit.

The second printed wiring board 65B is used for the electric room 6
4 and is fixed to the distal end surface of the substrate mounting portion 145 by screws 146. The second printed wiring board 65B is provided with an electric circuit forming the control operation unit 25 (see FIG. 21) and a transmission circuit for transmitting the valve opening to an external device. Vessel 1
3 excitation coil 18, sensor 1 of feedback mechanism 7
1 and the like, the electric signal I0 is sent to the electropneumatic converter 13 and the feedback signal from the sensor 11 is input. The second printed wiring board 65B is connected to the first printed wiring board 65 by pins 154 and a connector 155 forming a connector jack.
A is electrically connected to A, whereby the signal of the valve opening degree by the transmission circuit is transmitted to the outside via the first printed wiring board 65A.

The present invention is not limited to the structure described in the above embodiment, and it goes without saying that the shape, structure, etc. of each part can be appropriately modified or changed. For example, in the above-described embodiment, the waterproof cap 130 is formed by forming the outer peripheral wall 130a as the outer side wall and the concentric first and second annular walls 13 as the inner side wall opposed to the outer circumferential wall 130a at a predetermined interval.
0c and 130d are formed, and openings 131, 135 and 136, which are air flow windows, are formed at different positions. For example, as shown in FIG. 16, the inner side wall is formed by one annular wall 130d. May be.

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 waterproof cap 130 as shown in FIGS. When such a structure is employed, the position of the positioner 5 may be such that the waterproof cap 130 side is located below as shown in FIG. 18. At this time, in the structure of the above-described embodiment, the outer side wall 130 a , The air flow window 131 of the inner side wall 130d,
Depending on the height of the 135 from the cap ceiling surface 130b, it may be unavoidable that rainwater accumulates in the cap 130, but such a problem can be solved by the presence of the communication hole 137 for drainage described above. it can.

Even if such a structure is adopted, even if water intrudes from one of the air flow windows 131 or the communication holes 137, water will escape from the other air flow windows 131 or the communication holes 137, so that waterproofing is achieved. Water will not accumulate in the cap 130. For example, in such a structure, when the communication hole 137 is installed upward, rainwater or the like enters the cap 130.
From the drain. When installed horizontally, rainwater or the like entering from one communication hole 131 is drained from another air flow window 131 or the communication hole 137 described above.

As shown in FIG. 19, the air flow window 131 on the outer side wall 130a of the waterproof cap 130 described above.
And the height of the air flow window 135 of the inner side wall 130d higher than this is cut off to the same plane as the inner side surface of the ceiling portion 130b of the cap 130.
Obviously, even if the cover 122 is lower than the trumpet-shaped waterproof wall 133, substantially the same operation and effect as the case of the communication hole 137 described above can be obtained.

That is, with such a structure, even when the waterproof cap 130 side is positioned downward depending on the installation posture of the positioner 5, there is a problem that water accumulates in the waterproof cap 130 as shown in FIG. However, it is possible to reliably drain water from the air flow window 131 of the outer side wall 130a, and the waterproof effect can be further enhanced.

In the above-described embodiment, FIG.
As shown in FIG. 0, when the positioner 5 is mounted horizontally, each side wall 130a, 13a of the waterproof cap 130 is provided.
Even if the heights of the air flow windows 131 and 135 of 0d are low, they flow through the gaps between the respective flow windows and caps and the cover 122, bypass the trumpet-shaped waterproof wall 133, and flow downward.
It is clear that it is drained out.

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

Further, in the above-described embodiment, the case where the present invention is applied to the valve positioner 5 has been described. However, the present invention is not limited to this. A discharging mechanism, and this mechanism is provided with the case 6, the cover 122 and the waterproof cap 13;
A field-type pneumatic instrument covered by 0, as long as it has an air circulation hole in the instrument cover, is not limited to a positioner, and is applicable to various field-type pneumatic instruments including an electropneumatic converter. can do.

[0057]

As described above, according to the in-situ pneumatic instrument according to the present invention, the trumpet-shaped waterproof wall is formed so as to protrude 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 an air flow hole having a trumpet-shaped waterproof wall of the cover, and a plurality of air flow windows are formed on an outer side wall of the waterproof cap. And an inner side wall facing the air flow hole of the cover at a predetermined interval, and a plurality of air flow windows are provided on the inner side wall, and the air flow hole of the cover and the air on each outer side wall of the waterproof cap are provided. Since it is formed so as not to be on the straight line connecting the distribution window, it is possible to realize a waterproof structure that is easy to prevent rainwater etc. from entering the inside of the cover from the outside regardless of the installation position of the instrument despite its simple configuration. Therefore, according to the present invention, a complicated installation change operation for waterproofing, which was conventionally required, is not required.

Further, according to the on-site pneumatic instrument of the present invention, by providing a communication hole in the ceiling surface of the waterproof cap between the outer side wall and the inner side wall of the waterproof cap, one air circulation window or one communication hole is provided. Even if water enters, water can be drained from other air circulation windows or communication holes, and water does not accumulate in the waterproof cap even if the instrument is installed with the waterproof cap side down. You can do so.

Further, according to the in-situ pneumatic instrument according to the present invention, the height of the air flow window on the outer side wall of the waterproof cap is increased to a height substantially equal to the ceiling surface of the cap, and the height of the air flow window on the inner side wall is increased. By making the height lower than this, and even lower than the cover's trumpet-shaped waterproof wall, even if the waterproof cap side is located below due to the installation position of this in-situ pneumatic instrument, water will not enter the waterproof cap. Can be solved.
The waterproof effect can be further enhanced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an essential 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 a main part viewed from a different direction from FIG.

FIG. 3 is a plan view of FIG. 1;

4 (a) and 4 (b) are a bottom view and a side sectional view of a waterproof cap which characterizes 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 yoke of the valve.

FIG. 6 is 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 removed.

FIG. 10 is a rear view of the positioner with the cover removed.

FIG. 11 is a sectional view taken along line XI-XI of FIG. 6;

FIG. 12 is a cross-sectional view showing a mounting structure of the 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 a main part of the positioner.

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

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

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

FIG. 19 is a cross-sectional view of a principal part showing still another modified example in a state where the positioner has the waterproof cap facing downward.

FIG. 20 is a cross-sectional view of a main part for describing a use 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]

DESCRIPTION OF SYMBOLS 1 ... Valve, 2 ... Operating shaft, 3 ... Actuator, 4 ... Yoke, 6
... Explosion-proof case, 7 ... Feedback mechanism, 8 ... Feedback lever, 9 ... Connection pin, 10 ... Elongated hole, 11 ... Sensor, 12 ... Rotating shaft, 13 ... Electro-pneumatic 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 circuit 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 flow window); 133, trumpet-shaped rainwater intrusion prevention portion (trumpet-like waterproof wall); 137, communication hole.

Claims (3)

[Claims] An on-site pneumatic instrument having a mechanism for taking in air from the outside of the instrument or a mechanism for discharging air to the outside inside the instrument, and covering this mechanism with a case, a cover, and a waterproof cap. Has an air flow hole, and a trumpet-shaped waterproof wall is formed at an opening of the air flow hole so as to protrude outward. The waterproof cap covers the air flow hole having the trumpet-shaped waterproof wall of the cover. As described above, and a plurality of air circulation windows are formed on the outer side wall of the waterproof cap, and the inside of the outer side wall is opposed to this at a predetermined interval to cover the air circulation hole of the cover. A side wall is provided, and a plurality of air circulation windows are formed on the inner side wall. The air circulation window on the inner side wall is provided with an air circulation hole between the air circulation hole of the cover and each outer side wall of the waterproof cap. An on-site pneumatic instrument characterized by being placed out of the straight line connecting the window. 2. The on-site pneumatic instrument according to claim 1, wherein a communication hole is provided in a ceiling surface of the waterproof cap between an outer side wall and an inner side wall of the waterproof cap. . 3. The in-situ 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 equal to the height of the ceiling surface of the cap, and the air on the inner side wall is provided. An on-site pneumatic instrument wherein the height of the air flow window on the inner side wall is lower than the height of the flow window, and the height of the air flow window on the inner side wall is lower than the trumpet-shaped waterproof wall of the cover.