JPS63106402A - Electric-pneumatic relation converter - Google Patents

Abstract

PURPOSE:To facilitate and simplify an assembly adjustment work on the electroic-pneumatic element converter in the caption so as to reduce its cost by composing a flapper displacing means an exciting coil and a permanent magnet, and providing a magnetic body on the flapper opposing the permanent magnet. CONSTITUTION:On the displacing end 1a of a flapper 1 is installed an exciting coil 4A and a permanent magnet 4B which are means to convert an input signal to a displacement of the flapper 1, and a magnetic body 16 is installed on the flapper 1 opposing to the permanent magnet 4B. As the suction force due to the permanent magnet 4B can be, thus used as the bias force of a zero adjustment spring, a bias spring is unnecessary. An assembly adjustment work, accordingly, becomes simple and easy, while the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrical-to-air converter for converting electrical signals into pneumatic signals.

[Conventional technology]

It is well known that electrical signals and pneumatic signals are used as signal transmission media in industrial measurements.

Here, a current signal of 4 to 20 mA DC or a voltage signal of 1 to 5 V DC is generally used as the electric signal, and a 0.2 to 1.5 mA DC signal is used as the air pressure signal. OKp/c! i
is considered to be at a general level.

Fig. 3 is a schematic configuration diagram of a conventional general electric-pneumatic converter incorporated in a valve positioner, etc., in which 1 is cantilevered by a fulcrum 2 and is actuated in the thickness direction by an input signal IN (4 to 20 mA). The flapper to be displaced; 3 is a nozzle disposed close to and opposite the displacement end 1a of the flapper 1; 4 is an electromagnet; the electromagnet 4 is attached to the displacement end 1a of the flapper 1 and is excited by the input signal INK; It is composed of an excitation coil 4A and a permanent magnet 4B disposed corresponding to the excitation coil 4A. 5 is the zero adjustment spring.

For example, 6 is a bias spring that adjusts the output to 0.2 Ky/di with 4 mA input, and γ is a pilot valve.

8 is a feedback bellows, and 9 is an aperture.

Air Plup regulated to a constant pressure (0.2 to 1.0 KF) is supplied to the nozzle 3 via the throttle 9 and is injected toward the flapper 11C.

When an input signal IN of 4 to 20 mA is applied to the electromagnet 4, the input signal IN is converted into a displacement of the flapper 1 in the thickness direction according to Fleming's left hand rule. Then, since the distance between the flapper 1 and the nozzle 3 (nozzle-flapper gap) changes, the nozzle back pressure changes, and the nozzle back pressure is amplified by the pilot valve T to increase the air pressure commensurate with the displacement of the flapper 1. Obtain the signal Pout. This air pressure signal Pout is transmitted to a receiving instrument (not shown), while being branched and guided to the feedback bellows 8.

As a result, the flapper 1 tilts in a direction in which the rotational force generated by the input signal INK and the force generated by the air pressure signal Pout are balanced.

[Problems to be Solved by the Invention] By the way, the conventional electric-air converter of this type has two springs, namely a zero adjustment spring 5 and a bias spring 6.
In that case, the zero adjustment spring 5 should be used in either tension or compression (
The structure of both ends of the spring is different for tension and compression)
Therefore, the bias spring 6 always pulls the flapper 1 in the opposite direction to the force exerted by the zero adjustment spring 5.

Therefore, two springs are required for zero adjustment, which increases the cost.

[Means for solving problems]

The electric-air converter according to the present invention has been made to solve the above-mentioned problems, and includes means for displacing the flapper in response to an input signal, an excitation coil provided on the flapper, and a device corresponding to this coil. The fixed part is constructed with nine permanent magnets, and a magnetic body part is provided on the flapper in correspondence with the magnet, and the attractive force of the permanent magnet to this magnetic body part is used as a piascus of the zero adjustment spring. It is something.

[Effect]

In the present invention, the means for displacing the flapper according to an input signal is composed of an excitation coil and a permanent magnet, and a magnetic body portion is provided on the flapper corresponding to the permanent magnet, and a permanent magnet is disposed in correspondence with the magnetic body portion. Since the magnetic absorption force is used as the flapper's bias spring, a conventional bias spring is not required, and the zero adjustment spring can be constructed of a tension coil spring.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a front view showing an embodiment of an electric-air converter according to the present invention. Components in the figure that are the same as those in FIG. 3 are designated by the same reference numerals, and their explanations will be omitted. In the same figure, the fulcrum 2 that cantilevers one end of the flapper 1 is composed of two leaf springs 11A and 11B that are orthogonal to each other and one of them passes through the center hole of the other without contacting each other, and each leaf spring 11A, One end of the flapper 11B is screwed to the flapper 1 via an insulator 12, and the other end is screwed to the flapper mounting portion 13 via an insulator 14. The fulcrum 2 using such a cross spring is conventionally known. The flapper 1 is made of a non-magnetic material such as aluminum, and on the surface of its displacement end 1a facing the nozzle 3, a magnetic body 16 as a magnetic body part is provided, and means for converting an input signal into a displacement of the flapper 1. That is, electromagnet 4
It is fixed in correspondence with the permanent magnet 4B. Therefore, the magnetic body 16 receives an attractive force F from the permanent magnet 4BK, and this attractive force F acts to rotate the flapper 1 clockwise in the figure about the fulcrum 2, which causes the zero adjustment spring 5 to rotate. It composes Paiaska.

The zero adjustment spring 5 is made of a tension coil spring, and when its one end is locked to an adjustment screw 18 provided on the device fixing part and the other end is locked to an arm 19 provided on the flapper 1, the , the direction opposite to the direction in which the flapper 1 is rotated by the suction force F.

In other words, it is biased counterclockwise. The arm 19 is provided at a pivot point of the flapper 1 to protrude in a direction opposite to the displacement end 1a, and a weight 20 that balances the electromagnet 4 is attached to its tip.

In addition, illustration of the pilot pulp, feedback bellows, etc. in the figure is omitted. 21 breaths.

21b is the lead wire of the excitation coil 4A, 22&, 22b is a QJ for connecting each leaf spring 11A, 11B and the power supply.
- line.

According to the electric-air converter having such a configuration, the attraction force F of the permanent magnet 4B that attempts to attract the magnetic body 16 is the bias force of the one-legged spring 5, so that a conventional bias spring is not required. First, since it is only necessary to attach the magnetic body 16 to the flapper 1 in correspondence with the permanent magnet 4B, the structure is simple and the assembly work is easy. In addition, since the 7-lumbar 1 is always given a rotational behavior in one direction by the suction force F, the one-legged spring 5 can be used only in one direction, either tension or compression, to balance this suction force F. In particular, when a tension coil spring is used as in this embodiment, forming and fixing the hook portions at both ends is easier than when using a compression coil spring.

The degree of freedom in designing the spring itself is increased and it is easy to manufacture.

FIG. 2 is a sectional view of a main part showing another embodiment of the present invention.

In this embodiment, the flapper 1 is formed into a plate shape using SUG304, and both side edges thereof are bent approximately 90' toward the nozzle side. This s u s 304 is normally a non-magnetic material and is not attracted to a magnet, but when both edges are bent as in this example, the bent portions 30 & 30 b change into a magnetic material. This is well known, and these portions 30m and 30b are used as magnetic parts for the permanent magnet 4B to obtain a predetermined attractive force F.

In such a structure, there is no need to attach a magnetic body made of a separate member to the flapper 1, and the structure has the advantage of being simpler than the above embodiment.

〔Effect of the invention〕

As explained above, the electric-air converter according to the present invention is
The means for converting an input signal into a displacement of the flapper is composed of an excitation coil provided on the flapper and a permanent magnet arranged corresponding to this coil, and a magnetic body portion is attached to the flapper in correspondence with the permanent magnet. Since the structure 17 is configured such that the attractive force of the permanent magnet is used as the bias force of the one-leg spring, the assembly and adjustment work is simple and easy without the need for a bias spring. It can be used in only one direction, which is very advantageous in terms of design.

[Brief explanation of the drawing]

FIG. 1 is a front view showing one embodiment of an electric-air converter according to the present invention, FIG. 2 is a sectional view of main parts showing another embodiment of the present invention, and FIG. 1 is a schematic configuration diagram showing a conventional example. 1.0.・Flapper, 2.Fist...fulcrum, 3. . ...Nozzle, 4...Electromagnet, 4 people...Exciting coil, 4B...Permanent magnet, 5...One leg spring, 6...-Bias spring, 8... Feedback bellows, 16...magnetic material, 30m, 3
0b...Magnetic material part.

Claims (1)

[Claims] The flapper has one end supported in a cantilever and is displaced in response to an input signal, and a nozzle disposed close to and opposite to the displacement end of the flapper for converting the displacement of the flapper into a pneumatic signal. The means for displacing the flapper,
It is composed of an excitation coil provided on the flapper and a permanent magnet arranged on the device fixing part side corresponding to this coil, a magnetic body part is provided on the flapper corresponding to the magnet, and the magnetic body An electric-to-air converter characterized in that the attraction force of the permanent magnet to the part is used as a bias force of a zero adjustment spring.