JPH04203501A - Electropneumatic converting mechanism - Google Patents

Abstract

PURPOSE:To simplify and miniaturize a structure without using any nozzle- flapper mechanism so as to enhance machining and assembling accuracy by transmitting displacement of a displacement converting means according to an electric signal to a pilot valve. CONSTITUTION:One end of an electric displacement converting element 22 is fixed to one side of a frame body 21 while a pilot valve 24 is mounted on the other side thereof, thus making displacement of the electric displacement converting element 22 act on the tip end of a valve 25. The valve 25 is disposed in the main body of the pilot valve 24 while being held by a diaphragm 26, where one end of the valve 25 abuts against a ball 27 via a spring 28. A supply air pressure S is always supplied to a space for housing the ball 27 therein, and excessive air is discharged from an exhaust hole 31, thereby taking out an air pressure O according to an electric signal. Therefore, a structure can be simplified and miniaturized without using any nozzle-flapper mechanism, machining and assembling accuracy can be enhanced, and vibration resistance can be improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an electro-pneumatic converter having a structure in which a pilot valve is directly actuated without using a nozzle or a flapper as a means for converting displacement into air pressure. Concerning the conversion mechanism.

[Conventional technology]

A block diagram of a conventional electro-pneumatic converter is shown in FIG. 2, and a diagram of its operating principle is shown in FIG. This displacement is transmitted to the nozzle and the flapper 3 of the flapper mechanism, and is converted into nozzle back pressure PN as a change in the gap between the nozzle and the flapper. The nozzle back pressure PN is applied to the diaphragm 6 of the pilot valve 5, resulting in a displacement of the valve 7.
Press to open a gap between the steel ball 8 and ball seat 9, introduce the supply air pressure S to the output air pressure side, and take it out as the output air pressure O.

The branched output air pressure O is fed back to the bellows 10.
The force is transmitted to the feedback arm 11 as a force, and the position of the flapper 3 is balanced via the spring 12.

[Problem to be solved by the invention]

A conventional method of operating a pilot valve using nozzle back pressure using a nozzle-flapper mechanism as a displacement-air pressure conversion mechanism has the following problems.

1) Nozzle to obtain the highest value of nozzle back pressure.

Machining accuracy 9 for correctly assembling the gap between flappers
Assembly precision is required.

2) There is also a restriction that is always attached to the nozzle and flapper mechanism, and dirt from the air source adheres to the nozzle, flapper, and restriction during long-term continuous operation, which can eventually lead to clogging and deterioration of characteristics63) Because the flapper is a movable part due to its operating principle, its earthquake resistance is limited.

An object of the present invention is to provide an electro-pneumatic conversion mechanism that solves these problems.

[Means to solve the problem]

In order to achieve the above object, the nozzle and flapper mechanism, which serve as means for displacement-pneumatic pressure conversion, are excluded from the components of the electro-pneumatic conversion mechanism. That is.

A means for displacing by an electric signal is provided, and the displacement obtained by this means is transmitted to the valve in the pilot valve directly or via an expansion mechanism.

[Effect]

Using an element that generates displacement by applying an electrical signal,
Arrange the tip of the displacement so that it acts directly on the pilot valve, or if the displacement is less than the displacement required for valve operation, provide a displacement amplification mechanism and act on the pilot valve through this. By arranging it in such a manner, problems caused by using a nozzle and flapper mechanism can be eliminated, and long-term performance can be stabilized.

〔Example〕

Hereinafter, one embodiment of the present invention is shown in a block diagram in FIG. 4, and FIG. 1 shows the principle of operation.

FIG. 1 shows the case where an electric signal is applied to the element and the resulting displacement is directly transmitted to the pilot valve.

One end of the electric displacement converting element 22 is fixed to one side of the frame 21, and a pilot valve 24 is arranged on the other side of the frame 21, so that the displacement of the electric displacement converting element 22 acts on the tip of the valve 25. The valve 25 is a seal diaphragm 26
and is attached to the main body of the pilot valve 24.

The other end of the valve 25 is in contact with the ball 27;
is pressed against and in contact with the valve 25 side by a spring 28. A supply air pressure S is constantly supplied to the space provided with the ball 27. When the electric signal A is applied to the electric displacement converting element 22 and a displacement occurs, the displacement acts directly on the valve 25, and the displacement of the valve 25 is transmitted to the ball 27 and the ball 2
Open a gap between 7 and ball seat 29. The supplied air pressure S passes through this gap and is taken out as an output pressure of 0.

When the electric signal is in the decreasing direction, the displacement also becomes smaller and the valve 25 is pushed back by the spring 30, so the gap between the ball seat 29 is closed and the lower part of the valve 25 and the ball 2
There will be a gap between 7. From this gap, the output pressure is from valve 2.
It is discharged to the atmosphere through the exhaust hole 31 of No. 5, and the pressure is reduced.

Fig. 6 shows an example in which the displacement of the electric displacement converting element is applied to the pilot valve via an amplifying mechanism. If the displacement is not sufficient, it is necessary to increase the displacement by combining a plurality of electric displacement conversion elements 22 in series to obtain the necessary displacement, or by providing an expansion mechanism for the electric displacement conversion element 22 alone. be.

However, when a plurality of electric displacement transducing elements 22 are connected in series, there is a drawback that the entire device becomes large.

Therefore, in this embodiment, by providing a simple enlargement mechanism, performance can be obtained without increasing the size of the device. That is, in FIG. 6, a part of the frame 32 is made of an elastic material and is provided with a flexure 33 or a fulcrum 34 in place of the flexure 33, and is arranged so as to transmit the displacement of the electric displacement converting element 22 to a position 2 from the fulcrum 34. The pilot valve 24 is arranged so that a displacement acts in the direction opposite to Q from the fulcrum at a position L, and the pilot valve 24 is similarly installed on the center line of the fulcrum. That is, in this case, the valve 25 of the pilot valve 24 has L/
The displacement multiplied by I1 is transmitted. The adjusting screw 35 is for zero point position adjustment, and the lock nut 36 is for adjusting the zero point position.
This is for locking No. 5.

FIG. 7 shows a block diagram of an example in which the electro-pneumatic conversion mechanism 37 of the present invention is provided with a feedback circuit 39.The output pressure of the electro-pneumatic conversion mechanism 37 is taken out to the outside, and at the same time, the output pressure is branched. The air signal is guided to the pressure sensor and converted into an electrical signal again.

If a closed loop is constructed by providing a balanced circuit corresponding to the input signal as a feedback signal, a more accurate electro-pneumatic conversion mechanism can be completed. An example used is shown below.

The electromagnetic coil 42 is fixed inside the frame 41, and the frame 41-
A pilot valve 24 is arranged inside the other side, and a movable piece 43 and an adjusting screw 47 are connected to a relay arm 45 having a fulcrum 46 made of an elastic material between them with a connecting screw 49, and fixed with a fixing nut 48. The adjustment screw 47 is located at the center of the movable piece 43, and transmits the displacement of the movable piece 43 to the valve 25 of the pilot valve 24 via the relay arm 45, and the operation is the same as that in FIG. 4 described above. .

Arranging the pilot valve 24 to act on the displacement directly or via an amplification mechanism in this way can be easily considered as a means of electrical displacement conversion even when other elements are involved.

〔Effect of the invention〕

According to the present invention, the nozzle and flapper mechanism that are essential for converting displacement into air pressure can be omitted, which simplifies the structure.
Miniaturization is possible. Machining accuracy required to maintain minute gaps between nozzles and flappers.

Assembly precision is not required. In addition, during long-term operation, it eliminates the factors that cause performance deterioration due to dirt in the air source and adhesion to the nozzle and flapper.Furthermore, since it does not have a flapper, which is a moving part, it has the advantage of improving earthquake resistance.

Further, the pilot valve requires a diaphragm that generates displacement in response to nozzle back pressure, but a pilot valve that directly transmits displacement has the advantage that the diaphragm 6 shown in FIG. 1 can be omitted.

[Brief explanation of the drawing]

The first @ is a diagram of an embodiment of the electro-pneumatic conversion mechanism according to the present invention, and the second
The figure is a block diagram of a conventional product, Figure 3 is a diagram of the operating principle of a conventional product, Figure 4 is a block diagram of an embodiment of the present invention in which displacement is directly transmitted to the pilot valve, and Figure 5 is a diagram of the present invention. A block diagram of another embodiment of the invention, FIG. 6 is a cross-sectional view of the part surrounded by the dashed-dotted line in FIG. Fig. 8 is a block diagram of a case in which a deviation signal between an input signal and an output signal is detected in an electro-pneumatic converter to form a closed loop, and Fig. 8 shows another embodiment of the present invention in which the displacement of an electromagnetic coil is directly transmitted to a pilot valve. FIG. 22... Electric displacement conversion element, 24... Pilot valve, 25... Valve, 26... Seal diaphragm, 27... Ball, 28... Spring, 29...
... ball seat, 30 ... spring, 32 ... frame body,
33... Flexure, 34... Fulcrum, 35... Adjustment screw, 36... Lock nut, 37... Electro-pneumatic conversion mechanism, 38... Enlargement mechanism. 39... Feedback circuit, 41... Frame, 42
... Electromagnetic coil, 43 ... Movable piece, 44 ... Fixing screw, 45 ... Relay arm, 46 ... Fulcrum, 47 ...
...adjustment screws, 2nd and 3rd (sha) Δ)

Claims (1)

[Scope of Claims] 1. An apparatus for converting an electric signal into air pressure, comprising a displacement converting means for generating a displacement according to the applied electric signal, and a mechanism for transmitting the displacement of the means to a pilot valve. An electro-pneumatic conversion mechanism featuring: 2. In claim 1, the output air pressure from the pilot valve is converted into an electric signal by a pneumatic conversion element, and the electric signal applied to the displacement conversion means is controlled according to a deviation between the electric signal and the input signal. An electro-pneumatic conversion mechanism characterized by being equipped with a balance circuit.