JPH08177802A - Electro-pneumatic converter - Google Patents

Abstract

PURPOSE: To eliminate inconvenience such as troublesomeness or high manufacturing cost by eliminating torque difference between two different positions from a fulcrum due to a pair of magnets on a movable iron core. CONSTITUTION: Magnets 5, 6 are sandwiched between opposed legs 2a, 3a, and 2b, 3b of a pair of U-shaped yokes 2, 3 with a space through which a movable iron piece 4 is penetrated remaining on one side. A coil 7 is arranged, on a center space of a yoke so as to surround the yoke. A beam 11 having a flapper 13 opposed to the nozzle 14 is continued on one end of the movable iron piece. Zero-adjusting and bias-adjusting elastic members 15, 16 are connected to the free end of the iron core piece. A fulcrum member 9 is formed on an end of the movable iron piece exposed to outside and connected to the beam for oscillatably supporting them. A non-magnetic plate 20 abuts against on each one side of the movable iron piece of the paired yokes, while a ferromagnetic plate 21 is superposed on the outside thereof.

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 a force / displacement conversion mechanism such as various pneumatic instruments, electropneumatic positioners, electropneumatic converters, etc. The present invention relates to an electropneumatic converter using a motor.

[0002]

2. Description of the Related Art For example, an electropneumatic converter used for an electropneumatic positioner generates torque according to an input current as an electric signal and drives a nozzle flapper mechanism to convert the input current into a pneumatic signal. It is output as an air pressure output, and conventionally, various configurations are known.

As such an electropneumatic converter, one using a movable iron piece type torque motor as shown in FIGS. 2 (a) and 2 (b) is known. It is to be noted that FIG. 1A is a schematic configuration diagram of an electropneumatic converter indicated by reference numeral 1 as a whole, and FIG.
[Fig. 4] is a left side view of (a).

In these drawings, an electropneumatic converter 1 using this movable iron piece type torque motor has a pair of yokes 2, 3 which are substantially U-shaped and are arranged so that both legs thereof face each other. And each leg 2a, 3 of these yokes 2, 3
a; In the portion closer to one side as seen from the end face side between 2b and 3b,
The magnets 5 and 6 are sandwiched between the movable iron pieces 4 and the magnets 5 and 6 which are sandwiched between the movable iron pieces 4 and the yokes 2 and 3 so as to surround the movable iron pieces 4. A torque motor unit 8 including a coil 7 arranged is provided.

Reference numeral 4 denotes the above-mentioned movable iron piece, which is freely swingable by a fulcrum spring 9 whose right end portion in FIG. 2 (a) is bent into a substantially L shape as shown in FIG. 2 (c). Is disposed between the legs of the yokes 2 and 3 so as to pass through the space portion closer to one side and the central portion of the coil 7, and the left end portion is outside the left end portion of the yokes 2 and 3. Protruding through. In addition, reference numeral 10 in the drawing denotes a stopper that restricts the movable range of the left end portion (movable end) 4a of the movable iron piece 4. Further, one piece of the fulcrum spring 9 is screwed and fixed to the side wall portion of the yoke 3, so that the end of the movable iron piece 4 exposed from the space between the yokes 2 and 3 to the beam 11 is rocked. It will be movably supported.

Reference numeral 11 denotes a beam which is screwed to the end of the movable iron piece 4 on the side of the fulcrum spring 9 and is continuously provided. The beam 11 is also screwed to the other piece of the fulcrum spring 9, and this fulcrum spring is provided. The fulcrum of 9 is swingable.
Reference numeral 12 is a balancer attached to the right end (free end) of the beam 11. Reference numeral 13 is a flapper provided in the middle of the beam 11, and 14 is a nozzle provided in the fixed portion so as to face the beamer, which constitutes a well-known nozzle flapper mechanism.

That is, the supply air pressure Psup is the fixed throttle R
When the nozzle 14 is supplied through the nozzle 14, the nozzle back pressure Pn is generated according to the gap between the nozzle 14 and the flapper 13 facing the nozzle 14.
Is increased / decreased and amplified by a pilot relay or the like (not shown) to be output as an air pressure output Pout. Here, in the figure, reference numeral 15 is a zero adjustment spring for performing zero adjustment, and reference numeral 16 is a bias adjustment spring provided opposite thereto. Further, the yokes 2 and 3 described above are formed of permalloy or the like which is a general magnetic material. The magnets 5 and 6 are made of an appropriate ferromagnetic material.

In such a structure, the movable iron piece 4 is
It is arranged so as to pass through the inside of the coil 7 between the yokes 2 and 3, and is swingably supported about a portion supported by a fulcrum spring 9 on one end side thereof. And, as is apparent from FIG. 3, the movable iron piece 4 as described above has magnets 5, 6
The magnetic flux from flows through the movable iron piece 4 between the legs 2a, 3a; 2b, 3b of the yoke, and the magnetic attraction force F balances the movable iron piece 4 with the yoke legs 2a, 3a; 2b, 3b. Magnetic attraction force F
1, F2; F2, F1 are generated, whereby the movable iron pieces 4 are balanced and held at the neutral position by the attraction forces F1, F2.

Here, in FIG. 3, when the gap between the legs 2a, 3a; 2b, 3b of the yokes 2, 3 and the movable iron piece 4 is Lg, the legs 2a, 3a; 2b, 3b of the movable iron piece 4 are shown.
The magnetic attraction force directed to is as shown by F1 and F2 in the figure, and ideally these F1 and F2 are equal and balanced. Note that Φg is the magnitude of the magnetic flux between the gaps Lg, and the attractive force F increases or decreases in proportion to this.

On the other hand, when the drive current Ic is supplied to the coil 7 surrounding the movable iron piece 4 as described above, the movable iron piece 4 in the neutral position is, for example, as shown in FIG.
When the current flow is in the direction shown in the drawing in the portion where the magnetic flux of the air gap magnetic flux Φc is generated, the attraction force to the lower side in the drawing is such that the legs 2a, 3a; 3b, and as a result, swing displacement is performed downward in the figure. It goes without saying that when the current flows in the opposite direction, the current is oscillated and displaced upward.

That is, the movable iron piece type torque motor section 8 which operates according to the principle apparent from FIG. 3 described above.
In, the movable iron piece 4 generated by the magnets 5 and 6
The air gap magnetic flux that traverses the magnetic field changes with the drive current of the coil 7 surrounding the movable iron piece 4. Due to the increase or decrease in the air gap magnetic flux, the attractive force of the movable iron piece 4 changes, and torque is generated,
The movable iron piece 4 is swingably displaced to a required state. When such displacement occurs, the beam 11 integrally connected to the movable iron piece 4 swings, its flapper 13 advances and retreats with respect to the nozzle 14, the nozzle flapper gap changes, and the nozzle back pressure Pn.
Is increased or decreased to convert the output pressure Pout into a required pressure.

[0012]

In the conventional electro-pneumatic converter 1 as described above, the movable iron piece type torque motor section 8 is used.
Then, the magnetic attraction force acting positions of the magnets 5 and 6 of the movable iron piece 4 which is cantilevered by the fulcrum spring 9 are the position where the distance from the fulcrum is (La + Lb) and the position where it is Lb. In that case, there arises a problem that the air gap magnetic flux Φg at each position is different.
This is because the gap Lg between the left and right legs 2a, 3a; 2b, 3b of the movable iron piece 4 and the yokes 2, 3 at each position is different due to the swing displacement, and the magnetic attraction force generated at each portion by this difference. It is clear from the difference.

When such a problem occurs, a driving current Ic is passed through the coil 7, and the movable iron piece 4 is oscillated and displaced between the left and right legs 2a, 3a; 2b, 3b of the yokes 2, 3. Even if the forces F1 and F2 are generated, the left of the yokes 2 and 3,
A difference occurs in the attraction force generated on the movable iron piece 4 by the right magnets 5 and 6. As a result, the torque generated in the torque motor unit 8 varies and cannot be set to a constant value. As a result, the desired displacement output properly adjusts the nozzle flapper gap to obtain the desired output pressure Pout. It could not be said.

In such a conventional electropneumatic converter 1, the drive current Ic to the coil 7 by the above-mentioned torque motor unit 8 is used.
In order to obtain an air pressure output corresponding to the desired state, a complicated mechanical mechanism component that determines the output of the torque motor unit 8,
For example, as the zero adjustment and bias adjustment springs 15 and 16 using the fulcrum spring 9 and the coil spring, a plurality of types having different spring forces and the like are prepared, and further, their processing accuracy is increased, and these are appropriately selected. It was necessary to make adjustments that would be bothersome and costly to combine.

Further, in the electropneumatic converter 1 using the conventional movable iron piece type torque motor section 8 described above, it is held between the legs 2a, 3a; 2b, 3b of the pair of U-shaped yokes 2, 3. There is also a problem that the strengths of the magnets 5 and 6 vary widely. That is, when using the magnets 5 and 6 having different strengths, in order to make the generated torques at the positions corresponding to the magnets 5 and 6 of the movable iron piece 4 the same, the mechanical torque is the same as in the case described above. It is necessary to prepare a plurality of types of spring parts, which are mechanical parts, that is, zero adjustment and bias adjustment springs 15 and 16 by the fulcrum spring 9 and the coil spring, increase the spring machining accuracy, and combine them individually. However, this causes troubles such as troublesome adjustment work and increase in processing cost.

Further, according to the movable iron piece type torque motor unit 8 in the electropneumatic converter 1 as described above, the influence of the external magnetic field is reduced in principle because it is easily influenced by the external magnetic field. The magnetic shield of 1. is indispensable, and it is desired to take some measures in consideration of such a problem so as to eliminate the above-mentioned conventional problems.

The present invention has been made in view of such circumstances, and the magnetic attraction force (generated torque) generated at each position corresponding to the pair of magnets on the movable iron piece of the torque motor unit is generated from the fulcrum. Even if the distance is short or the magnet strength is varied, the balance can be made to be approximately the same, and several types of zero adjustment springs, fulcrum springs, etc. must be prepared and appropriately selected and combined, resulting in high cost. It is an object of the present invention to obtain an electropneumatic converter using a movable iron piece type torque motor that can eliminate conventional problems and can also exert a magnetic shield function that reduces the influence of an external magnetic field on the torque motor unit.

[0018]

In order to meet such a demand, an electropneumatic converter according to the present invention comprises a pair of U-shaped yokes arranged so as to face each other so that both legs face each other, and these yokes. The magnet is sandwiched between the two legs on one side and is disposed on the other side leaving a space through which the movable iron piece penetrates, and a pair of yokes is arranged to surround the movable iron piece in the central space. A coil, a beam having a flapper facing the nozzle and connected to one end side of the movable iron piece, an elastic member for zero adjustment and bias adjustment connected to the free end side of the beam, and a beam of the movable iron piece. A non-magnetic plate provided with a fulcrum member that swingably supports a portion connected to the beam at a portion exposed to the outside from the yoke, and is arranged in contact with a side surface portion of the pair of U-shaped yokes on the movable iron piece side. And overlap it on the outside Allowed are disposed is provided with a ferromagnetic material plate.

[0019]

According to the present invention, in a movable iron piece which is cantilevered by a fulcrum member, the torque generated at two positions corresponding to a pair of magnets arranged at different distances from the fulcrum is the strength of the magnet. Even if there is a torque difference due to variations, etc., a ferromagnetic plate having a magnetic shield function is placed on the side of the yoke through which the movable iron piece penetrates, and its mounting distance and mounting position. Can be adjusted arbitrarily to balance the generated torques and make them substantially the same.

[0020]

1 (a), 1 (b), and 1 (c) show one embodiment of the electropneumatic converter according to the present invention. In these figures, FIG. The same or corresponding parts as in (b) and the like are denoted by the same reference numerals and detailed description thereof will be omitted.

According to the present invention, in the electropneumatic converter 1 using the movable iron piece type torque motor (torque motor portion 8) as described above, the movable iron piece 4 in the pair of U-shaped yokes 2 and 3 is used.
The non-magnetic plate 20 arranged to be in contact with the side surface on the side (that is, the side surfaces on the side opposite to the magnets 5 and 6) and the ferromagnetic plate 21 arranged to overlap the outside thereof. It has a feature. In the figure, 22 and 22 are set screws for fixing the ferromagnetic plate 21 to the yokes 2 and 3 via the non-magnetic plate 20.

That is, in the present embodiment, when a torque difference is generated in the torque generated by the movable iron piece 4 which is cantilevered by the fulcrum spring 9, due to variations in the distance from the fulcrum, the strength of the magnets 5 and 6, and the like. In addition, the springs (9, 15, 16) are stacked on the side of the yokes 2, 3 through which the movable iron piece 4 penetrates without interposing a non-magnetic plate 20 without preparing and selecting several kinds of springs as in the conventional case. Magnetic coupling, for example, the mounting position, can be achieved by arbitrarily adjusting the mounting distance (the distance from the yokes 2 and 3 side, that is, the gap a depending on the thickness of the non-magnetic material plate 20) of the ferromagnetic material plates 21 arranged together. It is possible to adjust the generated torques and balance them so that they are substantially the same.

Further, in this embodiment, the ferromagnetic plate 21 is provided with a bent portion 21a which is bent to have a substantially L shape, and the torque motor portion 8 is formed by the bent portion 21a. The yoke 2 constituting the above is covered with a predetermined interval. As a result, the ferromagnetic plate 21 in this embodiment has a function of mechanically reinforcing the magnetic circuit for generating torque in the movable iron piece 4 by the yokes 2 and 3 and the magnets 5 and 6 in the torque motor unit 8. It is possible to reduce the influence of the external magnetic field in the torque motor unit 8 and to exert the function as a magnetic shield together. Further, in the above-mentioned configuration, the yokes 2, 3
By being attached to one side, the members constituting the magnetic circuit can be mechanically reinforced, and the advantage thereof is obvious.

In this embodiment, a plurality of (two in this embodiment) plate members having different thicknesses are used as the non-magnetic plate 20, and the ferromagnetic plates with the side surfaces of the yokes 2 and 3 are used. 21
It is effective in that the gap a can be appropriately selected and set. In particular, prepare a plurality of thin nonmagnetic plate 20,
By using these layers in layers, it is possible to cope with various thicknesses very easily. However, the present invention is not limited to this, and an appropriate number of non-magnetic material plates 20 having spacers having a plurality of types of thickness may be prepared, and these non-magnetic material plates 20 may be exchanged or appropriately stacked and used. In short,
It is sufficient that the nonmagnetic plate 20 has a configuration in which the gap a from the magnetic circuit formed by the yokes 2 and 3 of the ferromagnetic plate 21 can be arbitrarily set.

Here, the operation and effect of the above-described structure will be described in detail. The air gap magnetic flux that crosses the movable iron piece 4 in the torque motor unit 8 is the magnetic resistance of the magnets 5 and 6 and the magnetic circuit, and the non-magnetic plate by the spacer. Ferromagnetic material plate 2 which is a reinforcing member installed so as to sandwich 20 to short-circuit the magnetic circuit.
It is determined by the magnetic resistance with 1. Further, the torque generated in the movable iron piece 4 depends on the magnitude of the air gap magnetic flux that crosses the movable iron piece 4, provided that the drive current of the coil 7 has a constant value.
Further, the air gap magnetic flux that crosses the movable iron piece 4 can be changed by changing the thickness of the nonmagnetic plate 20 by the spacer, that is, the gap a.
Therefore, when the torque generated by the movable iron piece 4 described above is too large, the magnetic flux in the air gap can be reduced by reducing the gap a formed by the non-magnetic plate 20, and thus the generated torque can be reduced. become.

In particular, the above-mentioned change of the gap a can be made extremely easily by changing the thickness of the spacers forming the nonmagnetic plate 20, as described above. Further, as compared with the conventional case, a fulcrum spring 9, zero adjustment springs, and bias adjustment springs 15 and 16 are prepared and exchanged and adjusted in a large number of types, which is an extremely easy work, and is more effective than the conventional one. Can be demonstrated.

The present invention is not limited to the structure of the embodiment described above, but the structure, shape, etc. of each part of the electropneumatic converter 1 can be changed as appropriate.
It can be modified and various modifications are conceivable. For example, in the above-mentioned embodiment, the zero adjustment by the coil spring and the bias adjustment springs 15 and 16 are used as the elastic members for zero adjustment and bias adjustment connected to the free end side of the beam 11, and the yoke of the movable iron piece 4 is used. A fulcrum spring 9 formed by bending a plate material is used as a fulcrum member that swingably supports a portion connected to the beam 11 at a portion exposed to the outside from 2, 3 but the present invention is not limited thereto. Of course, as the elastic member and the fulcrum member, it is of course possible to appropriately use a conventionally known elastic body and a supporting member that can serve as a fulcrum.

[0028]

As described above, according to the electropneumatic converter according to the present invention, in the movable iron piece type torque motor, a pair of U-shaped yokes facing each other so that both legs face each other,
A magnet that is sandwiched between the yoke legs toward one side and is disposed with a space through which the movable iron piece penetrates left on the other side,
A coil disposed around the movable iron piece in the central space of the yoke, a beam having a flapper facing the nozzle and connected to one end side of the movable iron piece, and a zero connected to the beam free end side. Elastic member for adjustment and bias adjustment,
The movable iron piece is provided with a fulcrum member that swingably supports a portion connected to the beam at a portion exposed to the outside of the yoke, and is arranged in contact with side surfaces of the pair of U-shaped yokes on the movable iron piece side. Since the magnetic material plate and the ferromagnetic material plate arranged so as to be superposed on the outer side of the magnetic material plate are provided, there are various excellent effects listed below in spite of the simple structure.

That is, according to the present invention, even if a torque difference occurs in the torque generated by the movable iron piece cantilevered by the fulcrum member due to variations in the distance from the fulcrum, the strength of the magnet, etc. Without preparing and selecting several types as in the past, on the side where the movable iron piece of the yoke penetrates, a ferromagnetic material plate having a magnetic shield function is overlaid and arranged via a non-magnetic material plate, And the mounting distance can be adjusted arbitrarily, and magnetically coupled (specifically, the mounting position can be adjusted).
The generated torque can be balanced and made substantially the same by changing the above.

Further, according to the present invention, the magnetic attraction force (generated torque) generated at two different positions from the fulcrum of the movable iron piece by the pair of magnets in the torque motor unit is used to reduce the distance from the fulcrum and the magnet strength. Due to variations
It can be balanced as almost the same, eliminating the troublesome and costly conventional problems such as preparing several kinds of zero adjustment springs, bias adjustment springs, fulcrum springs, etc. and selecting and combining them appropriately, and A magnetic shield function that reduces the influence of an external magnetic field on the torque motor unit can also be exhibited.

[Brief description of drawings]

FIG. 1 shows an embodiment of an electropneumatic converter according to the present invention,
(A) is a schematic side view showing the overall schematic configuration, (b) is a left side view thereof, and (c) is a sectional view taken along the line CC of (a).

FIG. 2 shows an example of a conventional electro-pneumatic converter, (a) is a schematic side view showing the overall schematic configuration, (b) is a left side view thereof, and (c) is a movable iron piece that is swingably supported. FIG. 3 is a schematic perspective view of a fulcrum spring as a fulcrum member for

FIG. 3 is an operation explanatory view showing an operation principle of a movable iron piece type torque motor in the electropneumatic converter.

[Explanation of symbols]

1 ... Electro-pneumatic converter, 2, 3 ... Yoke, 2a, 2b; 3a,
3b ... legs, 4 ... movable iron pieces, 5, 6 ... magnet, 7 ... coil, 8 ... torque motor part, 9 ... fulcrum spring (fulcrum member), 10 ... stopper 11 ... beam, 12 ... balancer,
13 ... Flapper, 14 ... Nozzle, 15 ... Zero adjusting spring, 16 ... Bias adjusting spring, 20 ... Non-magnetic plate, 2
1 ... Ferromagnetic material plate, 22 ... Set screw.

Claims (1)

[Claims] 1. A pair of U-shaped yokes disposed so as to face each other so that both legs face each other, and a pair of U-shaped yokes sandwiched between the legs of the yokes, and the movable iron piece penetrates the portion closer to one side. A magnet arranged leaving a space, a coil arranged in the central space of the pair of yokes so as to surround the periphery of the movable iron piece, and a coil continuously provided on one end side of the movable iron piece and facing the nozzle. A beam having a flapper, an elastic member connected to the free end side of the beam for zero adjustment and bias adjustment, and a portion of the movable iron piece that is exposed to the outside from the yoke swings a connecting portion with the beam. A non-magnetic plate provided with a fulcrum member that is freely supported and arranged in contact with a side surface of the pair of U-shaped yokes on the side of the movable iron piece, and a non-magnetic plate superposed on the outside of the non-magnetic plate. With a ferromagnetic plate An electro-pneumatic converter characterized by being provided with.