JP3335568B2 - Instrument with built-in signal converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an instrument with a built-in signal conversion unit including a signal conversion unit such as an electropneumatic converter or an electropneumatic positioner.

[0002]

2. Description of the Related Art An electropneumatic converter and an electropneumatic positioner for a control valve can be cited as examples of an instrument with a built-in signal converter.
When used in an explosive gas atmosphere, such an instrument is required to have sufficient explosion-proof performance according to the explosion-proof standards. For this reason, a structure is employed in which the entire signal conversion unit is housed in an explosion-proof case formed of a special pressure-resistant container. The signal conversion unit changes the gap (nozzle gap) between the flapper and the nozzle by generating rotational torque in the flapper by the magnetic flux generated by the permanent magnet and the magnetic flux generated by energizing the excitation coil, and responds to the current flowing in the excitation coil. To obtain the output air pressure.

FIG. 7 is a schematic diagram showing a conventional example of an electropneumatic positioner for a control valve employing such a pressure-resistant explosion-proof structure, and FIG. 8 is a sectional view showing an electropneumatic converter. In these figures, an electropneumatic positioner 1 converts a displacement of an operating shaft 3 of a valve 2 into an electric signal I1 by a displacement detecting unit 4 such as a potentiometer, and feeds back the electric signal I1 to a control calculating unit 5, Feedback signal and positioner 1
By comparing the input signal I0 with the input signal I0 and transmitting the difference to the electropneumatic converter (signal converter) 6, the relationship between the instrument signal and the valve shaft position is always accurately controlled against disturbance.

[0004] The control operation unit 5 has an input detection unit, a CPU and the like. The electropneumatic converter 6 includes a yoke 7 formed in an E-shape.
An exciting coil 8 and a permanent magnet 9 attached to the legs 7a, 7b, 7c of the yoke 7, and the exciting coil 8
And a nozzle flapper mechanism 12 for converting the signal into an air pressure signal proportional to the supply current to the nozzle. The yoke 7 is provided at the same time as the formation of the explosion-proof case 15 by insert molding or the like and penetrating through the case wall, so that the tips of the three legs 7a, 7b, 7c project outside the case,
A permanent magnet 9 is fixed to the distal end surface of the center leg 7b with the N pole facing upward in FIG. 2 and the S pole facing downward. The excitation coil 8 is mounted on the left and right legs 7a, 7c of the yoke 7,
It is excited by the input signal I0.

The nozzle flapper mechanism 12 includes a flapper 10 disposed opposite to the legs 7a, 7b, 7c of the yoke 7.
And a nozzle 11 disposed so as to be close to and opposed to one end of the flapper 10. The flapper 10 is made of a magnetic material, and has a fulcrum spring 13 at the center in the longitudinal direction.
Is supported in the initial state by the two coil springs 16a and 16b, so that the gap with the nozzle 11, that is, the nozzle gap G is kept constant. The nozzle 11 is supplied with the supply air pressure Psup from the air supply source, and when the nozzle gap G changes due to the swing of the flapper 10, the nozzle back pressure PN also changes. The nozzle back pressure PN is configured to be amplified by the pilot relay 17 and then output to the drive device 18 of the valve 2 as the output air pressure Pout.

The explosion-proof case 15 is made of a weak magnetic material or a non-magnetic material, and constitutes an explosion-proof chamber 20. The displacement detector 4, a part of the electropneumatic converter 6, and a span adjusting switch 21 are provided. , A span adjustment screw 22, a zero adjustment switch 23, a zero adjustment screw 24, a terminal block 25, and the like. A case 26 houses the pilot relay 17 and is attached to one side wall of the explosion-proof case 15. 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, and 33 is a lever for feeding back the movement of the operating shaft 3 of the valve 2 to the valve positioner 1. It is. In FIG. 8, the arrow indicated by the solid line indicates the direction of the magnetic flux generated by the permanent magnet 9, and the arrow indicated by the dotted line indicates the direction of the magnetic flux generated by the exciting coil 8.

In such a structure, when the input signal 10 is not supplied to the valve positioner 1, the flapper 10 is held at a predetermined position where the magnetic attraction by the coil springs 16a and 16b and the permanent magnet 9 is balanced. Have been. At this time, the supply air pressure Psup is supplied to the nozzle 11 through the pipe 27, but the nozzle back pressure PN is kept constant because the flapper 10 does not swing. Therefore, the output air pressure Pout of pilot relay 17 is also constant.

The input signal I0 to the valve positioner 1 is
For example, it changes in the range of 4 mA to 20 mA. At 4 mA, the valve 2 is held in a fully closed state, and at 20 mA, the valve 2 is held at a fully open state. In the fully closed state of the valve 2, the feedback lever 33 that rotates in conjunction with the operation shaft 3 is stopped at a position where the feedback lever 33 has rotated a maximum angle clockwise in FIG. 7. In this state, when a current is applied to the exciting coil 8, a magnetic field in the direction opposite to the direction of the magnetic field generated by the permanent magnet 9 is generated in the left leg 7a, and the right leg 7c is generated.
, A magnetic field in the same direction as the direction of the magnetic field generated by the permanent magnet 9 is generated. Therefore, the suction force F with respect to the flapper 10 decreases on the left side, and the suction force F increases on the right side. Therefore, a clockwise rotation torque proportional to the supply current is generated in the flapper 10 with the fulcrum spring 13 as the center.
0 is brought closer to the nozzle 11. Therefore, the nozzle gap G decreases, the nozzle back pressure PN increases, and the current signal I0
Generates a pneumatic signal proportional to. The air pressure signal is amplified by a pilot relay 17 and output as an output air pressure Pout to be output to a driving device 18.
To work. Therefore, the operating shaft 3 moves upward to open the valve 2. Further, the movement of the operation shaft 3 is transmitted as a force for rotating and displacing the feedback lever 33 in the counterclockwise direction in FIG. When the feedback lever 33 rotates, the current value of the electric signal I1 input as a feedback signal from the displacement detection unit 4 to the control calculation unit 5 gradually increases, and the current value of the input signal I0 in accordance with the set value increases. The difference between the two decreases, and the valve opening is stabilized when the difference current becomes zero. The operation of returning from the valve open state to the fully closed state is an operation opposite to the above. Therefore, the valve 2 can be automatically controlled.

In such an electropneumatic positioner 1 for an explosion-proof control valve, in order for the electropneumatic converter 6 to accurately convert an electric signal into a corresponding pneumatic signal, the yoke 7 constituting the electropneumatic converter 6 is used. It is required that components such as the flapper 10 and the nozzle 11 be mounted with high accuracy and have a structure that is not easily affected by externally transmitted vibrations and shocks.

The operation of the electropneumatic converter 6 is of a normal operation type (the larger the electric signal, the larger the air pressure signal).
And the reverse operation type (the larger the electric signal, the smaller the pneumatic signal). There are two types, which are selected depending on the operation of the valve controlled on site. Here, if a change occurs in which the positioner controls a valve that operates in the opposite direction to the valve that has been controlled up to now, or the positioner that controlled the valve has failed and it is necessary to quickly replace it with a spare positioner If the operation of the spare positioner differs from that of the valve, the operation of the electropneumatic converter 6 is changed by connecting the plus and minus of the exciting coil 8 to the connection terminal in the field in reverse.

[0011]

As described above, there are two types of electro-pneumatic converters 6 incorporated in the conventional electro-pneumatic positioner 1 for explosion-proof type control valves, a normal operation type and a reverse operation type. Is determined according to the operation of the valve. However, during operation, the positioner controls a valve that operates in the opposite direction to the valve that has been controlled up to now, or the positioner that controlled the valve breaks down and it is necessary to replace it with a spare positioner immediately. In the case where the operation of the spare positioner differs from that of the valve, it is necessary to change the operation of the electropneumatic converter 6 on site.

However, in such a case, in order to reverse the increase / decrease relationship between the input signal I0 and the output air pressure Pout, the explosion-proof case 15 is opened and the plus and minus of the exciting coil 8 are connected in reverse to the terminals. Since the polarity (+,-) of the current is reversed, there is a problem that the change operation is troublesome.

Further, when replacing movable parts such as the wrapper 10 and the nozzle 11 which are liable to be damaged by disturbances such as vibrations, the nozzle gap G is required to have stable characteristics and strict dimensions.
Therefore, there is a problem that the characteristic adjustment after the change is troublesome.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. It is an object of the present invention to easily change the operation of the signal conversion unit and to prevent the dimensions from being changed due to vibration, impact, and the like. It is an object of the present invention to provide an instrument with a built-in signal conversion unit which can be assembled with a small number of components with high accuracy.

[0015]

In order to achieve the above object, a first aspect of the present invention is to provide a magnetic component which is provided through an explosion-proof case made of a weak magnetic or non-magnetic material to form a magnetic field, and A first magnetic field generating means provided on the magnetic structure, a swingable displacing means provided outside the explosion-proof case so as to face the first magnetic field generating means, and a magnetic field applied to the displacing means. A second magnetic field generating means for applying the magnetic field, and a displacement detecting means for detecting a displacement of the displacing means, wherein the second magnetic field generating means is opposed to the displacing means at a protruding end projecting outside the magnetic structure. It is characterized in that it is provided so that it can be turned upside down.

According to a second aspect of the present invention, there is provided a magnetic member which penetrates an explosion-proof case formed of a weak magnetic or non-magnetic material and forms a magnetic field, and a first member provided on the magnetic member.
Magnetic field generating means, a displacing means comprising at least two magnetic materials for branching a magnetic path of the magnetic field, a second magnetic field generating means for applying a magnetic field to the displacing means, and a displacement for detecting a displacement of the displacing means Detecting means for projecting an open portion of the magnetic component to the outside of the explosion-proof case, disposing the displacement means at the open portion in a swingable manner, and connecting the second magnetic field generating means to the explosion-proof case. It is characterized by being provided externally so that it can be turned upside down. In the first and second inventions,
By arranging the second magnetic field generating means outside the explosion-proof case, the operation can be changed simply by reversing the polarity of the magnetic field generating means. An exciting coil is used as the first magnetic field generating means, and a permanent magnet is used as the second magnetic field generating means.

In a third aspect based on the second aspect, the displacement means includes two magnetic members opposed to each other with an open portion forming member forming an open portion of the magnetic component interposed therebetween. A seesaw structure is formed by swingably supporting the magnetic body by a fulcrum spring. In the third aspect of the present invention, the two magnetic bodies and the fulcrum spring are unitized to form a seesaw structure, so that the attachment is easy, and the fulcrum is elastically deformed in the torsion direction by utilizing the fulcrum spring. There are no wear parts in the part, it is resistant to vibration, impact, etc., and the accuracy is improved.

In a fourth aspect based on the third aspect, the seesaw structure is swingably attached to the open portion forming member of the magnetic component, so that the magnet unit is formed together with the open portion forming member. And the opening forming member is detachably attached to the main body of the magnetic structure. In the fourth aspect of the present invention, the seesaw structure and the opening forming member of the magnetic component are formed as a unitized magnet unit, so that the apparatus can be made compact and the unit can be replaced when parts are replaced. Therefore, the replacement work is easy, the dimensional deviation due to vibration, impact, etc. is small, and the parts can be assembled with high accuracy, thus facilitating the adjustment work.

In a fifth aspect based on the fourth aspect, the magnet unit is provided so as to protrude outside the explosion-proof case and can be turned upside down, and the displacement detecting means is provided so as to be able to advance and retreat with respect to the displacement means. It is characterized by having. In the fifth invention, the polarity of the second magnetic field generating means is reversed by reversing the magnet unit, so that the switching to the normal operation type or the reverse operation type is possible. In addition, since it protrudes outside the explosion-proof case, there is no need to open the explosion-proof case, and the operation of changing the operation of the signal conversion unit is facilitated.

Further, a sixth aspect of the present invention relates to the first, second, and third aspects.
In the inventions of 3, 4, and 5, the displacement detecting means is an air nozzle whose advance and retreat is adjusted by an adjusting screw. In the sixth aspect, the distance between the nozzle and the displacement means can be easily adjusted by providing the air nozzle so as to be adjustable.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a diagram showing a basic configuration of the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG. The same components as those shown in the section of the prior art are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In these figures, reference numeral 30 denotes a core which forms a magnetic structure by being formed of a magnetic material. The core 30 has a horizontal core portion 30 to which the exciting coil 8 is attached.
a, a U-shaped base 30A comprising left and right vertical cores 30b, 30c attached to both ends of the horizontal core 30a, and cantilevered at the upper ends of the respective vertical cores 30b, 30c. It is composed of two open portion forming members 31 and 32 attached. Opening forming member 31,
32 is a horizontal core part 30a, vertical core parts 30b, 30c
It is formed in the shape of a plate using the same magnetic material as that described above, and is cantilevered so as to oppose each other to the distal end surfaces of the vertical core portions 30b and 30c, and is detachably attached. These open portion forming members 31 and 32 project outside the explosion-proof case and form a magnet unit together with the flapper 10 of the nozzle flapper mechanism 12.

The flapper 10 includes two movable iron pieces 35 and 36 opposed to each other with the open portion forming members 31 and 32 interposed therebetween.
And a fulcrum spring 37 that swingably supports these movable iron pieces 35 and 36 to form a seesaw structure. Each movable iron piece 35, 36 and the opening forming member 31, 32
Appropriate gaps a, b, c, d, e, and f are formed between the permanent magnet 9 and the yoke 40, respectively.
The fulcrum spring 37 is composed of a leaf spring, and
Located in a space 34 formed between the opposing surfaces of 1 and 32,
Both ends are molded in the molding resin 39. The molding resin 39 is formed into a magnet unit by molding the open-portion forming members 31 and 32 and the fulcrum spring 37 by insert molding, and thereafter attaching the permanent magnet 9 and the yoke 40 to form a unit. However, the unitization method is not limited to this.

Near the both ends of the fulcrum spring 37 which are molded into the molding resin 39, narrow portions (not shown) are provided, and the flapper 10 is elastically deformed in the torsional direction of the narrow portions. Swinging is possible. The nozzle 11 constituting the nozzle flapper mechanism 12 together with the flapper 10 is disposed so as to be close to and opposed to one end of one movable iron piece 35.

Two permanent magnets 9 are used and attached to the yoke 40 so that the nozzle side has an N pole and the opposite side to the nozzle side has an S pole. The magnetic flux of the permanent magnet 9 passes through the N pole-gap e of the yoke 40 from the N pole and is branched into two at the movable iron piece 35, and the gaps a and a are respectively provided.
When it enters the movable iron piece 36 via the c-opening portion forming members 31 and 32 and the gaps b and d, it joins again, and the gap f and the yoke 4
It returns to the S pole of the permanent magnet 9 via the S pole of 0.

The magnetic flux of the exciting coil 8 is transmitted to the horizontal core 30a.
Through the opening forming member 31 via the vertical core portion 30b from the opening, the two are branched into two gaps a, b and the movable iron piece 35,
After passing through the gaps c and d and passing through the opening forming member 32 respectively, they merge again and return to the horizontal core portion 30a through the vertical core portion 30c.

The magnetic attractive force Fx in the gap X (X; a to d) is as follows: Fx = KΦx ² Sgx where K: proportional constant, Φx: magnetic flux of the gap X, Sg
x: Cross-sectional area of gap X. Sga = Sgb = Sg
Assuming that c = Sgd, Fx = K′Φx ² (K ′ = KSgx) In the gaps b and c, Φb = Φc = Φm + Φc, where Φm is a magnetic flux of a permanent magnet, and Φc is a magnetic flux of an exciting coil. Fb = Fc = K ′ (Φm + Φc) ^{2 For} gaps a and b, Φa = Φd = Φm−Φc Fa = Fd = K ′ (Φm−Φc) ² Generated torque T is T = ｛(Fb−Fa) + (Fc− Fd)｝ · l = K ″ Φm · Φc where 1 is the distance from the fulcrum of the flapper to the center of the gap, and K ″ is a constant. For example, if Φc = 0, T =
It becomes 0.

In the electropneumatic converter in which the two movable iron pieces 35 and 36 are arranged so as to face the open portion forming members 31 and 32, the exciting coil 8 is permanently connected to the four gaps a, b, c and d. The magnetic flux of the magnet 9 is superimposed on each. In this case, since the directions of the magnetic fluxes are the same in the gaps b and c, the magnetic fluxes are added, and the attractive force to the flapper 10 increases. Then, the difference between these attraction forces becomes the rotation torque T for swinging the flapper 10.

FIG. 3 is a sectional view showing an electropneumatic converter mounting structure according to an embodiment of the present invention, and FIG. 4 is a sectional view taken along line IV-IV of FIG.
5 is a sectional view taken along line VV of FIG. 3, and FIG. 6 is an exploded view. In these figures, the configuration of the electropneumatic converter is the same as the basic configuration shown in FIGS. 1 and 2. The explosion-proof case 15 is provided with a core 30 forming a magnetic component penetrating therethrough. The core 30 includes a horizontal core 30
a, a main body 30A comprising left and right vertical core portions 30b, 30c provided at both ends of the horizontal core portion 30a, and two space portions formed to be detachably attached to the vertical core portions 30b, 30c, respectively. Members 31 and 32 are provided. The vertical core portion 30a is located inside the explosion-proof case 15, and has an excitation coil 8 as first magnetic field generating means attached thereto. The vertical core portions 30b and 30c penetrate the explosion-proof case 15, and the protruding end thereof has
1 and 32 are detachably attached by screws 50 respectively.

The nozzle flapper mechanism 12 is composed of two movable iron pieces 35 and 36 and forms a displacement means.
And a nozzle 11 as a displacement detecting means for detecting the displacement of the flapper 10. Movable iron pieces 35, 36
Are arranged so as to be opposed to each other in parallel with the space portion forming members 31 and 32 interposed therebetween. In addition, these movable iron pieces 3
5 and 36 together with the fulcrum spring 37 form a seesaw structure 55 having a symmetrical shape. With a symmetrical shape,
When the seesaw structure 55 is used upside down, only the polarity of the permanent magnet 9 as the second magnetic field generating means is reversed, and a shape that has no other effect except for the reverse operation of the flapper 10. means.

The fulcrum spring 37 is formed of a thin metal plate, and is orthogonal to the longitudinal direction of the movable iron pieces 35 and 36. Both ends are molded in a molding resin 39, and the permanent magnet 9, the yoke 40 and the space are formed. Part forming members 31 and 3
2 together with a magnet unit 57. Further, narrow portions 58 are formed near both ends of both sides of the fulcrum spring 37 as shown in FIG. 4, and the flapper 10 swings by utilizing the elastic deformation of the narrow portions 58 in the torsional direction. Is possible. The fulcrum spring 37 is located in the space 34 formed between the opposed end faces of the space forming members 31 and 32, and movable iron pieces 35 and 36
Respectively. The magnet unit 57 protrudes outside the explosion-proof case 15, and can be easily removed from the main body 30A of the yoke 30 by removing the screw 50.

The mold resin 39 is formed in a disk shape, and two permanent magnets 9 are embedded at positions on the outer peripheral surface where the phases are different by 180 °, and are magnetically coupled by a yoke 40. Guide plates 61 and 62 are further detachably attached to the front and back surfaces of the mold resin 39 by screws 63. The nozzle 11 is attached to one end of the guide plate 61 on the front surface side so as to be close to and opposed to the movable iron piece 35. The nozzle 11 is formed of an air nozzle having an adjusting screw portion 65 at a tip end thereof, and is fitted into a recess of the mounting base 111 via an O-ring 118 so as to be able to advance and retreat, and the adjusting screw portion 65 is connected to the guide plate 61. Screwed into the screw hole. Therefore, when the nozzle 11 is turned by hand, the nozzle 11 is adjusted to move toward and away from the movable iron piece 35, whereby the nozzle gap G is adjusted.
When the magnet unit 57 is turned upside down, the guide plates 61 and 62 move the mold resin 3 as shown in FIG.
9 is temporarily removed.

In the positioner provided with the electropneumatic converter having such a structure, the magnet unit 57 is detachably attached to the yoke main body 30A projecting outside the explosion-proof case 15 by screws 50 and can be turned upside down. So, if there is a change to control the valve that operates in the opposite direction to the valve that has been controlled until now, or if the positioner breaks down, it will be necessary to quickly replace it with a spare positioner,
If the operation of the spare positioner and the valve is different, the magnet unit 57 is inverted and the permanent magnet 9
Need only be reversed. Therefore, it is not necessary to open the explosion-proof case 15 and connect the plus and minus of the exciting coil 8 to the terminals in reverse, and the operation change operation can be performed easily and quickly.

The flapper 10 and the fulcrum spring 37 are unitized to form a seesaw structure 55, and the seesaw structure 55, the permanent magnet 9, the yoke 40, and the space forming members 31, 32 are unitized to form the magnet unit 5
Since it is 7, it is sufficient to replace the entire unit at the time of component replacement, it can be mounted with high accuracy, installation and adjustment work is easy, and each component does not displace due to vibration, impact, etc., improving seismic resistance be able to. Further, since the fulcrum spring 37 is formed of a leaf spring and the flapper 10 is swingably supported by utilizing elastic deformation in the torsion direction, there is no need to urge the flapper 10 with a coil spring as in the conventional device. From this point, since the fulcrum portion is resistant to vibration, impact, and the like, and the fulcrum portion is not worn, stable accuracy can be secured for a long period of time.

In the above-described embodiment, 2
Although the example in which the flapper is constituted by the movable iron pieces 35 and 36 is shown, the present invention is not limited to this, and the flapper may be constituted by one movable iron piece.

[0035]

As described above, according to the instrument with a built-in signal converter according to the present invention, the second magnetic field generating means is disposed outside the explosion-proof case, so that the operation of the magnetic field generating means can be changed when the operation is changed. It is only necessary to reverse the polarity. Therefore,
There is no need to open the explosion-proof case and insert a hand into the inside, and connect the plus and minus of the exciting coil in reverse, making it possible to perform the change work easily and quickly.

Further, according to the present invention, since two magnetic members forming the displacement means and a fulcrum spring for swingably supporting these magnetic members are unitized to form a seesaw structure, mounting is easy. Also, by utilizing the elastic deformation of the fulcrum spring in the torsion direction, the fulcrum portion has no wear portion, and is excellent in vibration resistance and impact resistance, and can improve accuracy.

Further, according to the present invention, since the seesaw structure, the second magnetic field generating means and the space forming member are unitized to form a magnet unit, the apparatus can be made compact, and the unit can be replaced when parts are replaced. Since the replacement is easy, the replacement work is easy, the dimensions of the components are not disturbed by vibration, impact, and the like, and the components can be assembled with high accuracy. Further, since the operation of the signal conversion unit can be changed only by turning the magnet unit upside down, the change operation is easy.

Further, according to the present invention, since the nozzle is provided with the adjusting screw portion so as to advance and retreat, the nozzle gap can be easily adjusted.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a basic configuration of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a cross-sectional view illustrating an electropneumatic converter mounting structure according to an embodiment of the present invention.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a sectional view taken along line VV of FIG. 3;

FIG. 6 is an exploded view.

FIG. 7 is a schematic configuration diagram showing a conventional example of a positioner.

FIG. 8 is a cross-sectional view of the electropneumatic converter.

[Explanation of symbols]

8 ... exciting coil, 9 ... permanent magnet, 10 ... flapper, 11
... Nozzle, 12 ... Nozzle flapper mechanism, 15 ... Explosion-proof case, 30 ... Yoke, 30A ... Main body, 31,32 ... Space forming member, 35,36 ... Movable iron piece, 37 ... Support spring, 3
9 mold resin, 40 yoke, 55 seesaw structure, 57 magnet unit, 65 adjustment screw.

Claims (6)

(57) [Claims] 1. A magnetic component which is provided through an explosion-proof case made of a weak magnetic or non-magnetic material and forms a magnetic field; a first magnetic field generating means provided on the magnetic component; Swinging displacement means provided outside the explosion-proof case so as to face the magnetic field generation means, second magnetic field generation means for applying a magnetic field to the displacement means, and displacement for detecting the displacement of the displacement means A signal conversion unit built-in type, comprising: a detection unit; and the second magnetic field generation unit is provided at a protruding end protruding outside the magnetic structure so as to be opposed to the displacement unit and can be turned upside down. Instrument. 2. A magnetic component which is provided through an explosion-proof case formed of a weak magnetic or non-magnetic material and forms a magnetic field; a first magnetic field generating means provided on the magnetic component; A displacement means comprising at least two magnetic materials for branching a magnetic path; a second magnetic field generating means for applying a magnetic field to the displacement means; and a displacement detection means for detecting displacement of the displacement means. An opening portion of the body is projected outside the explosion-proof case, and the displacement means is swingably disposed at the opening portion, and the second magnetic field generating means is provided outside the explosion-proof case so as to be capable of being turned upside down. A meter with a built-in signal converter. 3. An instrument with a built-in signal conversion unit according to claim 2, wherein the displacement means comprises two magnetic bodies opposed to each other with an opening forming member forming an opening of the magnetic component interposed therebetween. An instrument with a built-in signal converter, wherein a magnetic body is swingably supported by a fulcrum spring to form a seesaw structure. 4. The instrument with a built-in signal converter according to claim 3, wherein the seesaw structure forms a magnet unit together with a member for forming an open portion of a magnetic component and a second magnetic field generating means, and the member for forming an open portion is provided. Is an instrument with a built-in signal converter, which is detachably attached to the main body of the magnetic component. 5. The instrument according to claim 4, wherein the magnet unit is provided outside the explosion-proof case so that the magnet unit can be turned upside down, and the displacement detecting means is provided so as to be able to move forward and backward with respect to the displacement means. An instrument with a built-in signal converter. 6. The signal conversion device according to claim 1, wherein the displacement detecting means is an air nozzle that is adjusted forward and backward by an adjusting screw. Built-in type instrument.