JPH07139505A - Electric-pneumatic converter - Google Patents

Abstract

PURPOSE:To remove the inclination characteristics due to gravity and obviate reregulation on the spot and obviate the support point member of a flapper and the curtailment of the number of parts and compactness are realized, and facilitate spring assembly work by using compression coil springs instead of pulling coil springs and remove hysteresis. CONSTITUTION:A bobbin 38 is slidably fitted to a coil fitting portion 33 provided on the inner bottom surface of a yoke 32 through a permanent magnet 14. The bobbin 38 is supported by means of a pair of upper and lower compression coil springs 39, 40. A nozzle 15 is provided on the upper surface of the coil fitting portion 33, and a flapper 44 is provided on the inner surface of the bobbin 38 in approximate opposition to the nozzle 15. A zero regulation member 47 is screwed to the upper surface opening portion of the yoke 32, and by this, a nozzle.flapper opening (d) is regulated variably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electropneumatic converter suitable for application to an electropneumatic positioner or the like.

[0002]

2. Description of the Related Art This type of electropneumatic converter is used in an electropneumatic positioner or the like as shown in FIG.
It is configured so that o is converted into an air pressure signal to obtain a required output pressure Pout. Here, FIG. 4 is a block diagram showing the operating principle of the valve positioner, 1 is an arithmetic unit having a CPU or the like to which an input signal Io is input, 2 is an electropneumatic converter, 3 is an electropneumatic converter 2. A feedback sensor for detecting the output pressure Pout outputs the output pressure Pout obtained according to the input signal Io in the electropneumatic converter 2, and the output pressure Pout is detected by the feedback sensor 3 to generate an electrical signal. It is fed back to the calculation unit ₁ by I ₁ , and is corrected when a deviation occurs.

The specific configuration and operating principle of the electropneumatic converter 2 described above will be briefly described with reference to FIGS. 5 and 6.
In these figures, 9 is a flapper made of a magnetic material, 1
Reference numeral 1 is a fulcrum that supports the flapper 9 so that it can be oscillated.
Reference numeral 12 is a yoke including coils 13a and 13b, a permanent magnet 14, and a nozzle 15. The yoke 12 is formed in a substantially E shape in a front view, and thus has three leg portions 12a, 12b and 12
have c. The arrow a shown by the broken line in FIG. 6 indicates the direction of the magnetic field by the permanent magnet 14 in which the flapper 9 side is the N pole and the opposite side is the S pole, and the arrow b shown by the solid line is the N pole and the S pole. Coils 13a, 13 obtained in
The direction of the magnetic field by b is shown. Here, both coils 13a,
The polarity of 13b is set to be opposite.

When a current is passed through the coils 13a and 13b, a magnetic field is generated in the same direction as the magnetic field of the permanent magnet 14 on the left leg 12a side of the yoke 12, and conversely on the right leg 12b side. A magnetic field is generated in a direction that cancels the strength of the magnetic field of 14. Therefore, the force F for attracting the flapper 9 is increased on the left side and is weakened on the right side on the contrary, so that the counterclockwise rotation torque T proportional to the supply current Io is generated in the flapper 9 about the fulcrum 11. Therefore, the flapper 9 includes the leg portion 1 on the left side of the yoke 12.
2a, the nozzle gap, that is, the nozzle flapper gap d is reduced, and the nozzle back pressure PN accompanying the supply air pressure (Psup) supplied to this nozzle 15 is increased. An air pressure signal proportional to the current signal Io can be generated as the output pressure Pout.

Further, the flapper 9 described above has a pair of springs 16 and 17 as elastic members at both ends thereof.
It is provided between the base 18 as a fixed part and a predetermined tensile force is applied. The spring 16 on the left side is a biasing spring unit that biases the flapper 9 toward the nozzle 15. Further, the spring 17 on the right side is provided with a means 19 for adjusting the biasing force of the spring 17, thereby forming a zero adjusting mechanism 20 for setting the initial position of the flapper 9.

In FIG. 5, reference numeral 21 is a stopper provided at the tip of the right leg 12b of the yoke 12 corresponding to the nozzle 15, and 22 is a cross serving as a fulcrum spring which constitutes a fulcrum 11 for supporting the flapper 9. The spring 23 is a mounting bracket.

In such an electropneumatic converter 2, the diaphragm 2
A supply air pressure Psup is supplied to the nozzle 15 by an air flow path 25 having 4 and a nozzle back pressure PN on the downstream side of the throttle 24 is output as an output pressure Pout.

[0008]

By the way, in the conventional electropneumatic converter 2 as described above, since the nozzle flapper mechanism 3 constitutes a rotary system with the fulcrum 11 as a center, the inclination characteristic due to gravity is obtained. Have. That is, when the mounting posture of the electropneumatic converter 2 changes, the direction of gravity with respect to the flapper 9 also changes, and the displacement of the flapper 9 due to its own weight is
The flapper gap d (FIG. 5) is changed. For example, when the manufacturing adjustment is performed in the horizontal state shown in FIG. 5, the gravity G acts perpendicularly to the plane of the flapper 9, but when installed vertically, the gravity acts in the longitudinal direction of the flapper 9. Therefore, the nozzle flapper gap d changes. Therefore, there was a problem that readjustment was necessary at the site. Therefore, there is a demand for the development of an electropneumatic converter that is easy to install and adjust without being affected by gravity.

Further, since the flapper 9 and the zero adjustment mechanism 20 are arranged outside the yoke portion, the converter itself becomes large, and a tension coil spring is used as the bias spring 16 and the zero adjustment spring 17. Therefore, not only is it troublesome to hook the hook portions on both ends to the flapper 9 and the yoke side, but there are problems that hysteresis is caused and the hook portions are broken and fall off.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to eliminate the inclination characteristic due to gravity, to eliminate the need for readjustment at the site, and the flapper. No fulcrum member is required and the number of parts can be reduced and the size can be reduced. Also, by using a compression coil spring instead of a tension coil spring, the work of assembling the spring is easy and hysteresis can be eliminated. To provide a converter.

[0011]

In order to achieve the above object, an electropneumatic converter according to a first aspect of the present invention is formed in a cylindrical shape with a bottom, and a coil mounting portion is provided at the center of the inner bottom surface via a permanent magnet. A yoke, a bobbin which is formed in a tubular body having an open lower end, is slidably fitted to the coil mounting portion and whose upper and lower ends are supported by springs, and a coil disposed on the outer peripheral surface of the bobbin. A zero adjusting member disposed in an upper end opening of the yoke and abutting on one spring supporting the bobbin, a nozzle is provided at a tip of the coil mounting portion, and the nozzle is closely opposed to the nozzle in the bobbin. A flapper is provided, and an air flow path communicating with the nozzle is formed in the coil attachment portion and the magnet.

An electropneumatic converter according to a second aspect of the present invention is formed into a bottomed cylindrical shape, a yoke having a coil mounting portion at the center of the inner bottom surface thereof via a permanent magnet, and a cylindrical body having an open lower end. A bobbin which is slidably fitted to the coil mounting portion and whose upper and lower ends are supported by springs, a coil disposed on the outer peripheral surface of the bobbin, and a cover disposed in the opening of the yoke. A zero adjusting screw member disposed on the cover and abutting one spring supporting the bobbin, the nozzle being provided on one of the surfaces of the bobbin and the zero adjusting screw member facing each other, and the flapper being provided on the other surface. Is disposed so as to closely face the nozzle.

[0013]

According to the present invention, since the bobbin is slidably fitted to the coil mounting portion of the yoke, the fulcrum of the nozzle / flapper mechanism is unnecessary, and even if the posture of the converter is changed, the gravitation Not affected. The spring is composed of a compression coil spring, and is elastically mounted between the yoke and the bobbin, and between the bobbin and the zero adjusting member, and supports the bobbin so as to be vertically movable.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a sectional view showing an embodiment of the electropneumatic converter according to the present invention. In addition, the same reference numerals are given to the portions corresponding to those in FIGS. 4 and 5 described above, and the description thereof will be omitted. In the figure, the electropneumatic converter 30 includes a yoke 32 arranged on a disk-shaped base 31. The yoke 32 is formed as a bottomed cylindrical body having an open upper surface, and a coil mounting portion 33 is provided at the center of the inner bottom surface thereof via the permanent magnet 14. The permanent magnet 14 and the coil mounting portion 33 are formed in a cylindrical body having the same outer diameter, and the center holes 35 and 36 thereof form an air flow path 25 communicating with the nozzle 15 arranged in the center of the upper surface of the coil mounting portion 33. Is forming.

Reference numeral 38 denotes a bobbin formed in a cylindrical body having an open lower surface. The bobbin 38 is slidably fitted on the coil mounting portion 33 and the permanent magnet 14 from above with a minute gap therebetween. The upper and lower surfaces are elastically supported by a pair of springs 39, 40. The coil 13 is disposed on the outer peripheral surface of the bobbin 38, and the coil ends 13a, 13
Reference numeral b is an insertion hole 42 formed through the peripheral surface of the yoke 32.
It is derived from the outside. Further, a plurality of air holes 43 for communicating the inside and the outside are formed through the upper surface of the bobbin 38, and a chip-like flapper 44 closely fixed to the nozzle 15 is fixed to the center of the inner bottom surface.

A compression coil spring is used as the pair of upper and lower springs 39, 40 for elastically supporting the bobbin 38. The upper spring 39 is mounted between the lower surface of the spring receiver 46 and the upper surface of the bobbin 38, while the lower spring 4
No. 0 is mounted between the lower surface of the bobbin 38 and the inner bottom surface of the yoke 32. The spring receiver 46 has a center hole 49 by being formed in a ring shape, and the bearing 4 is attached to the lower surface of the zero adjustment screw 47 screwed into the upper end opening of the yoke 32.
8 is rotatably disposed and the upper side spring 39
Supported by. The zero adjustment member 47 has a plurality of air holes 50 that communicate the inside and the outside of the yoke 32. When the zero adjustment member 47 is rotated and moved up and down, the bobbin 38 moves up and down to move the nozzle 15 and the nozzle 15. Flapper 44
The gap can be adjusted.

Supply air pressure passages 51 and 52, which communicate with the air passage 25, are formed in the base 31 and the yoke 32, respectively. A predetermined pressure is supplied through the supply air pressure passages 51 and 52 and the air passage 25. Supply air pressure Psu
When p is supplied to the nozzle 15 and the bobbin 38 moves up and down by the input signal Io supplied to the coil 13, the nozzle flapper gap d changes, and the nozzle back pressure PN
Changes. The nozzle back pressure PN is sent to the amplifier through the communication passage 55 provided in the base 31, and the output pressure Pou
It is supplied to the regulating valve as t. Reference numeral 57 is an O-ring.

Thus, in the electro-pneumatic converter 30 having such a structure, the bobbin 38 is vertically movably fitted to the coil mounting portion 33 and is supported by the pair of springs 39 and 40. Since the nozzle 15 is disposed on the upper surface of the bobbin 38 and the flapper 44 is disposed on the inner bottom surface of the bobbin 38 so as to closely face the nozzle 15, the fulcrum of the nozzle flapper mechanism that has been conventionally required is not necessary, and the number of parts is reduced and the structure is reduced. Can be simplified. Further, since the bobbin 38 is slidably fitted in the coil mounting portion 33, even if the mounting posture of the electropneumatic converter 30 is changed, the influence of gravity is not exerted, and an electropneumatic converter having no inclination characteristic is obtained. be able to. Therefore, the installation and adjustment are not affected by the installation site, and there is no need for readjustment on site. Further, since compression coil springs can be used as the springs 39 and 40 for supporting the bobbin 38, unlike the tension coil springs, there is no hook portion, the assembling work is easy, and the hook portion is broken and hysteresis due to the hook portion. There is no need to worry about the occurrence of. Furthermore, since the nozzle flapper mechanism and the springs 39 and 40 are incorporated in the yoke 32 in the present invention,
The converter itself can be compactly integrated.

FIG. 2 is a sectional view showing another embodiment of the present invention. In this embodiment, the flapper 4 is provided at the center of the upper surface of the bobbin 38.
4 is provided, and the upper opening of the yoke 32 is covered with a cover 60.
The nozzle 15 is disposed between the cover 60 and the bobbin 38, the zero adjusting screw member 62 is disposed between the cover 60 and the bobbin 38, and the nozzle 15 is disposed in the center of the lower surface of the zero adjusting screw member 62 so as to closely face the flapper 44. This point is different from the above embodiment in that a communication hole 64 for communicating the air flow path 25 and the nozzle 15 is formed inside the zero adjustment screw member 62.

The zero adjusting screw member 62 has a cylindrical portion 62a slidably inserted through an insertion hole formed in the cover 60 via an O-ring 65, and an outer periphery of a lower end portion of the cylindrical portion 62a. A disc portion 62b integrally formed on the surface and a male screw portion 62c integrally connected to the upper end of the tubular portion 62a and screwed into the screw hole portion of the cover 60 are integrally provided.
A nozzle 15 is arranged at the center of the lower surface of 2b. Also,
A spring holder 4 is provided on the lower surface of the zero adjustment screw member 62.
6 is disposed, and the spring receiver 46 is pressed against the lower surface of the disk portion 62b via the bearing 48 by the upper compression coil spring 39. The air flow path 25 is formed inside the cover 60, and the inner end of the air flow path 25 communicates with the communication hole 64 through a small hole 66 formed on the peripheral surface of the upper end portion of the cylindrical portion 62a. The supply air pressure Psup is supplied to the nozzle 15 through the insertion hole 64. Further, the cover 60 has a communication hole 55 for leading the nozzle back pressure PN to the outside.
It is formed so as to communicate with 5. Reference numeral 67 is a nut for fixing the zero adjustment screw member 62. The other structure is substantially the same as that of the above-mentioned embodiment. Even in such a configuration,
The same effect as that of the above-mentioned embodiment can be obtained.

FIG. 3 is a sectional view showing still another embodiment of the present invention. In this embodiment, the nozzle 15 is arranged at the center of the upper surface of the bobbin 18, and the cover 60 is provided on the upper surface of the yoke 32.
A zero adjustment screw member 70 is provided through the cover 60, and the flapper 14 is provided at the center of the lower surface of the screw member 70 for the nozzle 1.
It is arranged so as to face and closely face 5. The zero adjustment screw member 70 includes a columnar portion 70a, a disc portion 70b integrally provided at the lower end of the columnar portion 70a, and a male screw portion connected to the upper end of the columnar portion 70a and screwed into a screw hole of the cover 60. 70c
And a spring receiver 46 is disposed on the lower surface of the disc portion 70b. The spring receiver 46 is pressed against the disc portion 70b by a compression coil spring 39 via a bearing 48. Other configurations are similar to those of the embodiment shown in FIG. Even with such a configuration, the same effect as that of the above embodiment can be obtained.

[0022]

As described above, according to the electropneumatic converter of the present invention, since the nozzle flapper mechanism and its zero adjustment mechanism are incorporated in the yoke, the converter itself can be miniaturized. Further, according to the present invention, since the bobbin is slidably fitted to the coil mounting portion provided in the yoke and the nozzle or flapper is disposed on this bobbin, there is no inclination characteristic due to gravity, and even if the mounting posture is changed, it can be used on site. Readjustment is not required. In addition, since the fulcrum of the nozzle / flapper mechanism is not needed, the number of parts can be reduced, and since the bobbin can be supported by the compression coil spring, the work of assembling the spring is easier than the tension coil spring having the hook part. Thus, the effect is extremely large, such as eliminating the hysteresis.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of an electropneumatic converter according to the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the electropneumatic converter according to the present invention.

FIG. 3 is a sectional view showing still another embodiment of the electropneumatic converter according to the present invention.

FIG. 4 is a block diagram showing the operating principle of the valve positioner.

FIG. 5 is a cross-sectional view of essential parts showing a conventional example of an electropneumatic converter.

FIG. 6 is a diagram showing an operating principle of an electropneumatic converter.

[Explanation of symbols]

 2 electro-pneumatic converter 3 nozzle flapper mechanism 9 flapper 11 fulcrum 12 yoke 13 coil 14 permanent magnet 15 nozzle 20 zero adjustment mechanism 25 air flow path 32 yoke 33 coil mounting portion 38 bobbin 39 spring 40 spring 47 zero adjustment member 60 cover 62 zero adjustment Screw member 63 Spring 70 Zero adjustment screw member Psup Supply air pressure Pout Output pressure PN Nozzle back pressure

Claims (2)

[Claims] 1. A yoke having a bottomed cylindrical shape and a coil mounting portion provided at the center of the inner bottom surface thereof via a permanent magnet, and a cylindrical body having a lower end opened so as to be slidable on the coil mounting portion. A bobbin which is fitted to the coil and whose upper and lower ends are supported by springs, a coil which is arranged on the outer peripheral surface of the bobbin, and a zero which is arranged at the upper end opening of the yoke and abuts one spring supporting the bobbin. An adjusting member is provided, a nozzle is provided at the tip of the coil mounting portion, and a flapper that closely faces the nozzle is disposed in the bobbin, and an air flow path communicating with the nozzle is provided in the coil mounting portion and the magnet. An electropneumatic converter characterized by being formed. 2. A yoke having a cylindrical shape with a bottom and provided with a coil mounting portion through a permanent magnet at the center of the inner bottom surface, and a tubular body having a lower end opened so as to be slidable on the coil mounting portion. A bobbin fitted on the upper and lower ends of which is supported by springs, a coil disposed on the outer peripheral surface of the bobbin, a cover disposed in the opening of the yoke, and the bobbin disposed on the cover. A zero adjusting screw member that abuts one of the supporting springs, and a nozzle is disposed on one of the surfaces of the bobbin and the zero adjusting screw member that face each other, and a flapper is disposed on the other face so as to closely face the nozzle. An electro-pneumatic converter characterized in that