DE10235353B4 - positioner - Google Patents

Abstract

Positioner for positioning actuators in control valves, being provided between actuator and controller coupling means in the form of a return shaft, characterized in that the return shaft (1) to the inner wall of the positioner housing (10) is guided, and magnetic entrainment elements (2, 3 ) the rotational position of the return shaft (1) is transferable to an externally arranged rotary position indicator element.

Description

The invention relates to a positioner for positioning actuators in control valves, wherein coupling means are provided in the form of a return shaft between the actuator and controller, according to the preamble of claim 1.

Positioners are most often used as valve actuators for large process valves. The said valves of large nominal size require a precise determination of the valve rod positions for the controlled intervention in the process. The valve rod can either be hubbetätigt or rotationally actuated, after which then designed the corresponding specific design of the Abgriffsmittel. An example in the prior art are rotary actuated valves. Here, a valve drive is provided which have output shafts on two diametrically opposite sides of the drive. The lower output shaft acts by appropriate coupling to the mechanical actuating means of the valve. The upper output is fed to the actual positioner. The positioner is attached to known designs, via a standard mounting bracket on the valve drive. Between the drive side facing the controller output side of the drive and the controller itself takes place a mechanical coupling. For this purpose, the controller also has a shaft output, which is coupled to the output shaft of the valve drive.

In order to identify the regulated valve position at a greater distance, it is necessary to install an indicator. Such indicators, which simply use the rotational movement of the return shaft of the regulator for displaying, are for example from DE 44 14 191 A1 known.

More problematic is the interpretation of such a display device in controllers with Exd claim, since the required housing breakthroughs for optical detection can be implemented only with disproportionately high cost, eg. B. Using bulletproof glass and observing accurate fitting flame paths.

From the DE 196 52 583 C1 an electric actuator with a positioner is known, which is connected via a return shaft to the actuator, wherein the return shaft is guided to the inner wall of the positioner housing and its rotational position is measured by means of magnetic elements.

Furthermore, from the JP 63-043 085 A an optical display element for the Venilstellung known.

The invention is therefore the object of developing a positioner for positioning actuators in control valves to the effect that the position of the return shaft is readable in compliance with the Exd conditions, and the design is as simple as possible gestalltet.

The object is achieved according to the invention in terms of a device of the generic type by the characterizing features of claim 1.

Further advantageous embodiments of the fluid-operated actuator according to the invention are specified in the dependent claims.

The core of the invention is in this case that the return shaft is guided to the inner wall of the controller, and the rotational position of the return shaft can be transferred to an externally arranged rotary position indicator via magnetic driver elements.

In an advantageous embodiment, it is stated that the positioner housing according to Exd (DIN EN 50018) is designed flameproof encapsulated.

Furthermore, it is advantageously provided that the rotary position indicator is arranged dust-proof in a provided with a window surface protective housing, which is arranged at the appropriate position on the positioner housing.

All in all, the invention is suitable for any drive design. The position or the rotational position of the return shaft can be read easily, although the positioner housing explosion-proof according to DIN EN 50018 is executed.

The designs can be single-acting, double-acting, linear or pivoted. In each of the cases mentioned, the stated advantages over known designs can be achieved. The invention is illustrated in the drawing and described in more detail below.

It shows:

1 : Cover arrangement of a positioner according to the invention.

2 : Arrangement on rotary actuator.

1 shows in a sectional side view of the cover assembly of a positioner according to the invention 10 , This serves to position the actuator in control valves. The valve as such is not shown here. The return shaft 1 that leads to the actuator or to the valve actuator is with a co-rotating magnet 2 connected. The return shaft 1 with the magnet 2 ends below the lid 11 this arrangement. In known positioners, the return shaft would be guided by a rotary feedthrough to the outside to be read from the outside in its rotational position.

However, in order to meet the aforementioned Ex-protection and Exd-protection requirements, the rotational movement of the below the cover is here in the inventive manner 11 ending return shaft 1 by means of a magnet 2 at the return shaft 1 is attached, magnetkraftschlüssig on a rotatable magnet 3 transfer that above the lid 11 is arranged. This is in a double-walled cap 12 rotatably mounted, and is in terms of its rotational movement from the magnet 2 the return shaft 1 taken. In this way it serves as a lead-free rotary coupling.

The rotational position of the return shaft 1 can through a window 13 thus easy to read from the outside, without a guided outward shaft would have to be sealed. In this way, all prerequisites of Ex and Exd protection are fulfilled.

2 shows a positioner with positioner 10 in its closed design. At the mounting flange 30 is to recognize the drive shaft, which is guided down to the valve not shown here.

LIST OF REFERENCE NUMBERS

1

Feedback shaft

2

magnet

3

magnet

10

Positioner housing

11

cover

12

Double-walled plastic cap

13

window

30

mounting flange

Claims (3)

Positioner for positioning actuators in control valves, wherein between the actuator and controller coupling means are provided in the form of a return shaft, characterized in that the return shaft ( 1 ) to the inner wall of the positioner housing ( 10 ) is guided, and via magnetic entrainment elements ( 2 . 3 ) the rotational position of the return shaft ( 1 ) is transferable to an externally arranged rotary position indicator. Positioner according to claim 1, characterized in that the positioner housing ( 10 ) according to Exd (DIN EN 50018) is pressure-tight encapsulated. Positioner according to claim 1 or 2, characterized in that the rotary position indicator element is protected against dust in one with a window surface ( 13 ), as a double-walled cap ( 12 ) executed protective housing is arranged, which at the appropriate position on the positioner housing ( 10 ) is arranged.

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