JPH071302U - Electro-pneumatic converter - Google Patents

Abstract

(57) [Summary] [Purpose] The electropneumatic converter holds the flapper in a magnetically balanced position when the supply air pressure is exhausted. In addition, the gap between the nozzle and flapper should be easily adjusted. [Structure] Elastic members 20 and 21 are connected to both ends of a flapper 10 facing a nozzle 15 and swingable with respect to a yoke 12. A piston cylinder 30 is arranged so as to face the non-nozzle side extending portion 10a of the flapper 10. One end 31a of the piston rod 31 is projected to the outside of the cylinder to face the extending portion. Further, the supply air pressure Psup or the nozzle back pressure PN is introduced into the cylinder chamber 32 on the protruding end side of the piston rod, and the elastic member 3 is introduced into the other cylinder chamber 33.
4 is provided. When the supply of the supply air pressure or the nozzle back pressure is cut off, the protruding end of the piston rod abuts on the non-nozzle side extending portion of the flapper, and holds the flapper in a horizontal state.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electropneumatic converter suitable for application to an electropneumatic positioner or the like.

[0002]

[Prior art]

 This type of electropneumatic converter is used, for example, in a valve positioner or the like as shown in FIG. 5, and is configured to convert an electric signal IO into a pneumatic signal to obtain a required output pressure Pout. Here, FIG. 5 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 the input signal I0 is input, 2 is an electropneumatic converter, and 3 is an electropneumatic converter. The output pressure Pout obtained from the electropneumatic converter 2 in accordance with the input signal I0 is output by the feedback sensor for detecting the output pressure Pout from the output pressure Pout, and the output pressure Pout is detected by the feedback sensor 3. The electric signal I1 is fed back to the arithmetic unit 1 and is corrected when there is a deviation.

Here, the electropneumatic converter 2 described above will be briefly described with reference to the operating principle shown in FIG. 6 and the specific example shown in FIG. 7. In these figures, 10 is a flapper and 11 is a flapper. 10 is a fulcrum that supports swingable displacement, and 12 is a yoke having coils 13a and 13b, a permanent magnet 14, and a nozzle 15, and has a substantially Y-shaped cross section and three legs. It has 12a, 12b, 12c. The arrow a shown by the wavy line in FIG. 6 indicates the direction of the magnetic field by the permanent magnet 14 in which the flapper 10 side is the N pole and the opposite side is the S pole, and the arrow b shown by the solid line shows the N pole and the S pole. The direction of the magnetic field by the coils 13a and 13b thus obtained is shown. Here, the polarities of the coils 13a and 13b are set to be opposite to each other.

When a current flows 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 on the contrary, on the right leg 12b side. Then, a magnetic field is generated in a direction in which the strength of the magnetic field of the permanent magnet 14 is canceled out. Therefore, the force F for attracting the flapper 10 on the left side increases, and the force F on the right side weakens on the contrary, so that a counterclockwise rotation torque T about the fulcrum 11 is generated in the flapper 10 in the counterclockwise direction. Therefore, the flapper 10 is brought closer to the nozzle 15 provided at the tip of the left leg 12a in the yoke 12, the nozzle gap, that is, the nozzle flapper gap is reduced, and the flapper 10 is driven by the supply air pressure (Psup) supplied to the nozzle 15. The back pressure PN of the nozzle is increased, so that an air pressure signal proportional to the current signal I 0 can be generated as the output pressure Pout.

Here, in FIG. 7, reference numeral 16 is a stopper provided on the tip of the right leg 12 b of the yoke 12 in correspondence with the nozzle 15, 17 is a base on which the yoke 12 is provided, and 18 supports the flapper 10. A cross spring as a fulcrum spring forming the fulcrum 11 and a mounting bracket 19 for the fulcrum.

Further, the flapper 10 described above is provided with a pair of springs 20 and 21 as elastic members at both ends thereof between the flapper 10 and the base 17 as a fixed portion, and is given a predetermined tensile force. There is. Here, the spring 20 on the left side is a spring means for biasing which biases the flapper 10 toward the nozzle 15. Further, the spring 21 on the right side is a spring means for adjusting the zero point for setting the initial position of the flapper 10 by attaching a means 22 for adjusting the biasing force.

FIG. 9 shows a connection state with the air pressure passage in the electropneumatic converter 2 as described above. The supply air pressure passage 24 having the throttle 23 supplies the supply air pressure Psup to the nozzle 15 and the throttle 23. The nozzle back pressure PN on the downstream side of is output as the output pressure Pout.

By the way, in the electro-pneumatic converter 2 as shown in FIG. 6, FIG. 7, FIG. 9 and the like, the input current I0 to the coils 13a and 13b via the arithmetic unit 1 is a predetermined value from 4 mA to 20 mA. When the flapper 10 is swung in the required direction via the fulcrum 11, 0% F. S, 50% F.I. S, 100% F.I. The position of S etc. will be appropriately displaced.

In such electro-pneumatic converter 2, the magnetic balance at each displacement position by the flapper 10 and the coils 13a, 13b and the permanent magnet 14 is the magnetic flux density, the strength of the magnetic field, the residual magnetic flux density, Considering from the magnetic hysteresis curve characteristics obtained by magnetic force, hysteresis, etc., the flapper 10 has a fulcrum 11 so that the flapper 10 is in a substantially horizontal state. It has been confirmed that at the position of S, the gaps of the left and right magnetic circuits are equalized and magnetically balanced.

[0010]

[Problems to be solved by the device]

 By the way, in the electro-pneumatic converter 2 as described above, when the supply air pressure Psup is not supplied to the nozzle 15 and there is no input signal IO to the coils 13a and 13b, the flapper 10 is set to 0 in FIG. % F. It is in the S position. However, in this state, the magnetic balance in the flapper 10 and the like is lost and the magnetic hysteresis is large, so the problem of zero-point shift occurring if left in this state for a long time can be avoided. It was not there.

When such a zero-point shift occurs, the zero-point adjustment must be readjusted, and the zero-point adjustment must be performed by opening the case such as a positioner and watching the output pressure gauge for adjusting the spring 21. It is necessary to adjust the urging force by the adjusting means 22. Moreover, an arbitrary electric signal (for example, 0%, 50%, 100%) is applied to the coils 13a and 13b, and the output pressure at that position is set to a normal value. There is a problem that the operation is troublesome and complicated, and it is desired to take some measures to prevent such a zero point shift.

Further, in the above-described conventional electropneumatic converter 2, each member has the following functions. That is, the permanent magnet 14 has a function of attracting and holding the flapper 10 downward in order to obtain vibration resistance of the flapper 10 and a torque T for rotationally displacing the flapper 10 in cooperation with the magnetic fields generated by the coils 13a and 13b. It is a thing. The bias spring 20 is for keeping the nozzle-flapper gap at a predetermined value in equilibrium with the rotational torque T. Further, the spring 21 for adjusting the zero point is used to set the output pressure Pout with a predetermined current signal to a predetermined value (for example, when Psup = 2.2K, it is set to 1.0K at 0.3mA). It is a thing.

In the electropneumatic converter 2 having such a structure, the one that determines the span includes the initial inclination of the flapper 10 viewed from the fulcrum 11, the spring constant of the fulcrum 11 (by the cross spring 18), and the bias. And the spring constants of the springs 20 and 21 for adjusting the zero point and the spring constant due to the air jet from the nozzle 15, and what determines the zero point is the gap between the flapper 10 and the nozzle 15 when viewed from the fulcrum 11 ( 48 μm; horizontal state at 0.3 mA).

Under such conditions, the nozzle flapper characteristics are as shown in FIG. 10. In this case, if the zero point adjustment is performed by setting the nozzle flapper gap to 48 μ, The flapper 10 may be in a horizontal state with respect to the permanent magnet 14, but due to variations among the respective components, such a horizontal state relationship is often not obtained, and the flapper 10 is inclined to either one. As a result, the span changes, as is clear from the characteristics shown by the broken line in FIG. 10. Therefore, the bias spring 20 and the zero point adjusting spring 21 must be changed to springs having different spring constants. There is also a problem in terms of practical use that it must be done.

In order to eliminate such a problem, in order to keep the flapper 10 in a horizontal state and prevent the span from changing, each part must be formed with a considerably high accuracy, which is substantially the same. However, it is also desirable to take some measures that can solve the above-mentioned problems in consideration of such points.

The present invention has been made in view of the above circumstances, and secures magnetic balance when not in use when supply air pressure of a flapper, which is swingably arranged with respect to the yoke, is exhausted, and a magnetic balance is ensured. The purpose is to obtain an electropneumatic converter that prevents the occurrence of hysteresis and zero-point shift due to being left for a long time, and does not require troublesome zero-point adjustment.

Further, according to the present invention, by configuring the nozzle / flapper gap to be adjusted very easily, it is possible to eliminate the deviation of the zero point by a simple operation, and the troublesome zero point adjustment as in the past The purpose is to obtain an electropneumatic converter that does not require.

[0018]

[Means for Solving the Problems]

 In order to meet such a demand, the electropneumatic converter according to the present invention is swingably disposed on a yoke, has a nozzle facing one extending portion, and has elastic members connected to both ends thereof. The flapper is provided with a piston cylinder that is disposed so as to face the extension on the side opposite the nozzle, and one end of the piston rod of this piston cylinder is projected outside the cylinder to face the extension on the side opposite the nozzle, and When the supply air pressure or nozzle back pressure is introduced into the cylinder chamber on the protruding end side of the ton rod and the elastic member is installed in the other cylinder chamber, the piston rod protrudes when the supply of supply air pressure or nozzle back pressure is cut off. The end of the flapper is brought into contact with the extended portion of the flapper on the side opposite to the nozzle to hold the flapper in a horizontal state.

Further, the electropneumatic converter according to the present invention is arranged such that the nozzle of the flapper, which is swingably arranged with respect to the yoke and has elastic members connected to both ends thereof, at least faces the nozzle. A moving member that can move back and forth in the axial direction is provided.

[0020]

[Action]

 According to the present invention, when the supply air pressure is supplied, the projecting end of the piston rod is located away from the flapper, and the required attraction of the flapper is generated by the magnetic attraction force according to the input current supplied to the coil. The nozzle-flapper gap is controlled by the dynamic operation, the output pressure is obtained by the nozzle back pressure by this, and when the supply air pressure and the input current are lost, the protruding end of the piston rod is projected by the elastic member. The flapper is brought into contact with the stretched portion on the side opposite to the nozzle to hold the flapper in a horizontal state in which it is magnetically balanced and can prevent the zero point shift.

Further, according to the present invention, the adjustment of the nozzle-flapper gap can be easily and appropriately performed by moving and adjusting the movable member that is provided at a position facing the nozzle of the flapper and is movable in the axial direction of the nozzle. It is very easy to adjust the zero point.

[0022]

【Example】

 1 and 2 show an embodiment of the electropneumatic converter according to the present invention. In these figures, the same or corresponding parts as those in FIG. Detailed description is omitted.

According to the present invention, the yoke 12 including the coils 13a and 13b, the permanent magnet 14 and the nozzle 15 and the flapper 10 facing the nozzle 15 and swingably disposed on the yoke 12 are provided. The electro-pneumatic converter 2 having springs 20 and 21, which are elastic members connected to both ends of the flapper 10, and a piston cylinder 30 arranged to face the non-nozzle side extending portion 10a of the flapper 10. A piston rod 31 of the piston cylinder 30 has one end 31a projected to the outside of the cylinder 30 so as to face the non-nozzle side extending portion 10a, and a cylinder chamber 32 on the protruding end side of the piston rod is provided with a pneumatic circuit side. Nozzle back pressure PN is introduced from above, and a spring 34, which is an elastic member, is arranged in the other cylinder chamber 33. When PN supply is interrupted, the projecting end 31a of the piston rod 31 abuts against the counter-nozzle side extending portion 10a of the flapper 10, is characterized in was by Uni configured to hold the flapper 10 in a horizontal state.

According to such a configuration, when the supply air pressure Psup is supplied, the projecting end 31a of the piston rod 31 has the flapper 10 (extension on the non-nozzle side) as shown in FIG. Located apart from the portion 10a), the required swinging motion of the flapper 10 is obtained by the magnetic attraction force according to the input current I0 supplied to the coils 13a and 13b, and the nozzle-flapper gap x is controlled. The output pressure Pout can be obtained by the nozzle back pressure PN.

Further, when the supply air pressure Psup and the input current IO are lost, the projection end 31a of the piston rod 31 is projected by the spring 34 in the cylinder 30 to prevent the flapper 10 from rotating as shown in FIG. The flapper 10 can be held in a magnetically balanced horizontal state by abutting against the nozzle side extending portion 10a, and the zero point shift can be prevented. In this case, it goes without saying that the projection amount of the piston rod 31 is regulated at the position where the flapper 10 maintains the horizontal state.

According to such a configuration, since the flapper 10 can be held at a magnetically balanced position when the electropneumatic converter 2 is not used, the zero point shift which is a conventional problem can occur. Even if it is left in that state for a long period of time, the zero point shift due to magnetic hysteresis is prevented, and the troublesome re-adjustment operation can be eliminated, which is an excellent effect.

Here, in the above-described embodiment, the nozzle back pressure PN is introduced into the chamber 32 on the piston rod protruding end 31a side of the piston cylinder 30 for ensuring the magnetic balance of the flapper 10 when not in use. Although the case is illustrated, the present invention is not limited to this, and as shown in FIG. 3, the supply air pressure Psup is connected to the cylinder chamber 32 via the branch passage 24a on the supply side and supplied. However, it goes without saying that the same effects as those of the above-described embodiment can be obtained.

FIGS. 4A and 4B show another embodiment of the present invention. In these figures, the same or corresponding parts as those in FIG. The detailed explanation is omitted.

Now, according to the electro-pneumatic converter of this embodiment, at least the nozzle 15 of the flapper 10, which is swingably arranged with respect to the yoke 12 and has springs 42 and 43 as elastic members connected to both ends, respectively. It is characterized in that a screw member 40, which is a movable member that can move back and forth in the axial direction of the nozzle 15, is provided at a position facing to.

Further, according to such a configuration, the screw member 40 that is screwed at a position facing the nozzle 15 of the flapper 10 and that can move back and forth in the axial direction of the nozzle 15 is screwed appropriately. The nozzle flapper gap x can be adjusted extremely simply and appropriately by only adjusting it.

In particular, in such an embodiment structure, since the screw member 40 can easily adjust the nozzle / flapper gap x to a predetermined value, the spring 21 for adjusting the zero point as in the above-described embodiments. Also, it is not necessary to provide the biasing force adjusting means 22, and the conventional complicated zero point adjusting means is not required, and the cost can be reduced. In other words, with such a structure, the gap between the nozzle 15 and the nozzle 15 can be set to a predetermined value simply by adjusting the screwing amount of the screw member 40 to the flapper 10, and the zero point adjustment is extremely easy. Can be done.

The screw member 40 described above may be formed of a material having excellent wear resistance in consideration of wear and the like at the time of collision with the nozzle 15.

Further, in this embodiment, similarly to the screw member 40 provided at the position facing the nozzle 15 of the flapper 10 described above, the nozzle 15 faces the stopper 16 of the corresponding yoke 12 via the fulcrum 11. A screw member 41 having a similar structure is provided at the position to be adjusted as an adjusting member that can be adjusted forward and backward in the axial direction of the stopper 16.

According to such a configuration, the flapper 10 can be balanced through the fulcrum 11 and maintained in a horizontal state, which is also advantageous in that vibration resistance can be improved. In particular, in order to improve such vibration resistance, a screw member 41 may be provided on the stopper 16 side of the flapper 10 to have the same height as the screw member 40 on the nozzle 15 side.

The present invention is not limited to the structure of the embodiment described above, and it goes without saying that the structure, shape, etc. of each part of the electropneumatic converter 2 can be appropriately changed and modified. For example, a spring, an elastic member such as a spring, etc. It will be easily understood that various modifications are possible, including the structure of the fulcrum 11 that supports the flapper 10.

[0036]

[Effect of device]

 As described above, according to the electropneumatic converter of the present invention, the yoke is swingably arranged, the nozzle faces one of the extending portions, and the elastic members are connected to both ends. The flapper is equipped with a piston cylinder that is arranged so as to face the extended portion on the side opposite to the nozzle, and one end of the piston rod is projected outside the cylinder to face the extended portion on the side opposite the nozzle, and the protruding end of the piston rod is provided. Introducing supply air pressure or nozzle back pressure into the cylinder chamber on the side and arranging an elastic member in the other cylinder chamber allows the piston rod protruding end to be released when supply air pressure or nozzle back pressure is cut off. Since the flapper is held in a horizontal state by contacting the flapper with the extension on the non-nozzle side, the supply air pressure is supplied despite the simple structure. The piston rod protruding end is separated from the flapper, and the nozzle-flapper gap is controlled by the swing displacement of the flapper according to the input current supplied to the coil, and the required output pressure according to the nozzle back pressure is obtained. On the other hand, when the supply air pressure and the input current are lost, when the piston rod is not used, the projecting end of the piston rod projects by the elastic member inside the cylinder chamber and abuts on the non-nozzle side extending part of the flapper, and this flapper is magnetically balanced. It has a practically excellent effect in that it is locked and held in a horizontal state, and as a result, zero point shift can be prevented.

Therefore, according to the present invention, the flapper can be held at a magnetically balanced position when the electropneumatic converter is not used, and the zero point shift, which has been a problem in the past, can be generated. Even if it is left unattended for a long period of time, it prevents the occurrence of zero-point shift due to magnetic hysteresis, and can eliminate the need for troublesome readjustment operations.

Further, according to the electro-pneumatic converter of the present invention, the nozzle of the flapper, which is swingably disposed on the yoke and has elastic members connected to both ends thereof, at least faces the nozzle. Since a movable member that can move forward and backward in the axial direction is provided, it is possible to adjust the moving member that is movable forward and backward in a position facing the nozzle of the flapper in the axial direction of the nozzle despite the simple structure. This makes it possible to adjust the nozzle-flapper gap easily and appropriately, and to achieve zero point adjustment easily in the required state, which is an excellent practical effect.

[Brief description of drawings]

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

FIG. 2 is a schematic cross-sectional view for explaining an operating state of the electropneumatic converter shown in FIG.

FIG. 3 is a schematic cross-sectional view showing a modified example of the electropneumatic converter shown in FIGS. 1 and 2.

FIG. 4 shows another embodiment of the electro-pneumatic converter according to the present invention,
(A) is a schematic sectional drawing and (b) is a top view of a flapper.

FIG. 5 is a schematic configuration diagram of a valve positioner using an electropneumatic converter.

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

FIG. 7 is a schematic sectional view showing an example of a conventional electropneumatic converter.

FIG. 8 is a schematic diagram for explaining an operation relationship of the nozzle flapper.

FIG. 9 is a schematic sectional view showing another example of a conventional electropneumatic converter.

FIG. 10 is a characteristic diagram showing nozzle / flapper characteristics in a conventional electropneumatic converter.

[Explanation of symbols]

 2 electro-pneumatic converter 10 flapper 10a non-nozzle side extension 11 fulcrum 12 yoke 13a coil 13b coil 14 permanent magnet 15 nozzle 16 stopper 17 base 18 cross spring 20 bias spring (elastic member) 21 zero adjustment spring (elastic member) ) 22 urging force adjusting means 23 throttle 24 supply air pressure passage 30 piston cylinder 31 piston rod 31a piston rod protruding end 32 cylinder chamber 33 cylinder chamber 34 spring (elastic member) 40 screw member (moving member) 41 screw member (moving member) 42 Spring (elastic member) 43 Spring (elastic member) Psup Supply air pressure Pout Output pressure PN Nozzle back pressure IO Input current

Claims (2)

[Scope of utility model registration request] 1. An electric wire comprising a yoke having a coil, a permanent magnet and a nozzle, a flapper facing the nozzle and swingably disposed on the yoke, and elastic members connected to both ends of the flapper. In the air converter, a piston cylinder is provided facing the non-nozzle side extension of the flapper, and one end of a piston rod of the piston cylinder is projected outside the cylinder to face the non-nozzle side extension. At the same time, the supply of the supply air pressure or the nozzle back pressure is introduced into the cylinder chamber on the protruding end side of the piston rod, and the elastic member is arranged in the other cylinder chamber, whereby the supply of the supply air pressure or the nozzle back pressure is cut off. In this case, the protruding end of the piston rod abuts the extension portion of the flapper on the side opposite to the nozzle, and the flapper is held in a horizontal state. Pneumatic transducer collector, characterized in that. 2. An electric wire comprising a yoke having a coil, a permanent magnet and a nozzle, a flapper facing the nozzle and swingably disposed on the yoke, and elastic members connected to both ends of the flapper. In the pneumatic converter, an electropneumatic converter characterized in that a moving member that is movable back and forth in the axial direction of the nozzle is provided at a position facing at least the nozzle of the flapper.