DE102018001936A1 - Hydraulically damped actuator - Google Patents

Abstract

The invention relates to a pneumatic actuator for a fitting, comprising a housing (1) in which at least one pneumatic piston (2) is arranged, which acts on a rotating actuating shaft (4) via a piston rod (3) assigned to it, wherein the pneumatic piston ( 2) is coupled to a hydraulic damper, wherein a hydraulic piston (10) in a hydraulic cylinder between a first and a second working space (11, 12) is movable. In order to design such an actuator more reliable, it is proposed that the first and the second working space (11, 12) are connected via a hydraulic line (14) arranged outside the hydraulic cylinder. In particular, in this external hydraulic line, a diaphragm (16) can be integrated, which is accessible from the outside and thus easy to clean. This can also be combined with a throttle valve (15) in the hydraulic line (14).

Description

The invention relates to a pneumatic actuator for a valve, comprising a housing in which at least one pneumatic piston is arranged, which acts via a piston rod associated therewith on an adjusting shaft rotating about an axis, wherein the pneumatic piston is coupled to a hydraulic damper, wherein a Hydraulic piston is movable in a hydraulic cylinder between a first and a second working space.

Fittings of the type in question can be found in a variety of systems. With them by means of adjustable cross-sectional constrictions, a flow of material throttled or shut off. In this case, this valve, in particular in automatically operated systems, actuated by an actuator, which causes by adjusting force and travel this cross-sectional constriction.

It is known that the actuator contains one or more (usually two) interconnected pneumatically actuated volumes. By means of the pressure prevailing in this volume, the adjustment of the valve is effected by acting with the volume of corresponding pistons on a control shaft. For this purpose, a common solution is to provide the piston with piston rods, which mesh via teeth with a counter toothing on the control shaft.

In the known actuators, the pneumatic piston on springs or spring assemblies are biased so that they go in case of failure of their pneumatic supply or control in an end position, which is selected from the viewpoint of safety of the valve or system.

Depending on the type of installation or the throttled or regulated by means of the valve line and depending on the medium flowing in the conduit medium, even with a sudden failure of the pneumatic supply or control the valve does not abruptly go into said end position, as this within the system can lead to undesired pressure surges, which can cause damage to the affected system. In the worst case, cables or their brackets can be damaged. But also other fittings, pumps, foundations and other components of a piping system such. B. heat exchangers, etc. can be endangered by such pressure surges. It is u.a. problematic that corresponding damage to cables u.U. are not immediately apparent, e.g. when a flange is damaged, and thus can lead to delays only with delays.

It is therefore known to provide such pneumatic actuators with a hydraulic damper, so that even in an automatic process of the pneumatic piston this moves only slowly or delayed to its end position.

Within such a hydraulic damper, a hydraulic piston in a hydraulic cylinder between a first and a second working space is movable, wherein the two working spaces of the hydraulic cylinder are filled with a hydraulic fluid. During a corresponding movement of the hydraulic piston, hydraulic fluid flows through one of the pistons, which acts as a throttle, from one to the other working space. As a result, the movement of the hydraulic piston is damped and thus also the movement of the coupled with him pneumatic piston.

Basically, it is also possible with such a hydraulic damper to influence the actuating speed of the actuator.

It is understandable that the existing on the hydraulic piston bore is relevant for both the damping and for a set actuating speed. Their diameter, their design in terms of inlet and outlet, etc. influence the amount of hydraulic fluid that can flow through them and thus the speed at which moves the hydraulic piston between the first and the second working space.

It has now been found that e.g. In connection with improper maintenance, foreign or dirt particles from the hydraulic fluid have accumulated inside the bore, which can adversely affect the function of the damper.

In addition, there is an interest in being able to adjust the damping characteristics of the hydraulic damper if necessary, which is currently the case, for example. about the selection of the hydraulic fluid used is effected in terms of their viscosity.

It is therefore an object of the present invention to further develop a pneumatic damper with a hydraulic damper as stated above in such a way that difficulties encountered, e.g. due to maintenance problems are easier to control and if necessary, the adjustability of the damping is facilitated.

This object is achieved in that the first and the second working space of the hydraulic damper to be calculated hydraulic cylinder are connected via an outside of the hydraulic cylinder arranged hydraulic line.

The invention has the advantage that both maintenance and adjustment work can be carried out by the hydraulic line provided externally of the hydraulic cylinder, without the damper having to be disassembled, so that an installer can access the flow connection between the two working chambers located in the piston , Instead, when problems occur, as described above, you can work on the easily reached from the outside hydraulic line.

In a preferred embodiment of the invention, at least one throttle valve is provided in the hydraulic line. Such are available as reliable components and inexpensive purchased parts and ensure adequate reliability. Merely for the sake of good order, it should be mentioned that a corresponding throttle valve can also be designed as a throttle check valve. In the context of this application, for ease of readability, therefore, when mentioning a throttle valve, it is understood as an alternative also a throttle check valve. These terms are thus used synonymously here.

Preferably, a corresponding throttle valve is also adjustable, whereby a desired change in the damping properties of the hydraulic damper not only by selecting and then replacing a suitable rigid throttle valve is possible, but a throttle valve, if necessary, can be adjusted by a suitable adjustment.

Alternatively or additionally, at least one aperture is provided in the hydraulic line. This has the particular advantage that their installation can be very space-saving.

In a preferred embodiment, it is provided that the aperture is indeed permanently installed but interchangeable. This is on the one hand to achieve that with a blockage of such a panel this very quickly and thus easily replaceable. But with this variant, the installation of an actuator in a system can also be very easily implemented as needed adjustment.

In a further preferred embodiment, the diaphragm is arranged parallel to the at least one throttle valve in the hydraulic line. This is achieved as a further advantage that in case of incorrect operation of the throttle valve, the aperture is still available as a security element.

Thus, the aperture does not disturb the actual control behavior of the throttle valve too much, it is proposed that the volume flow flowing through the aperture is at least an order of magnitude smaller than the volume flow flowing through the open throttle valve.

It should be mentioned that for ease of assembly, the hydraulic line provided outside the hydraulic cylinder, including any built-in components such as throttle valve and / or orifice, may be integrated in a connection block with standard connections. As a standard offer z. For example, NAMUR recommendations and worksheets.

About such a terminal block assembly costs of a device according to the invention can be further reduced.

In principle, a throttle valve can be fixed in a predeterminable position and this fixation can also be secured against unintentional cancellation. - This increases operational safety.

• 1 die Prinzipskizze eines pneumatischen Stellantriebes mit ergänztem Pneumatik- und Hydraulikanschlussplan,
• 2 die Aufsicht auf einen erfindungsgemäßen Stellantrieb.

Further advantages and features of the invention will become apparent from the following description of an embodiment. Showing:

• 1 the schematic diagram of a pneumatic actuator with a supplemented pneumatic and hydraulic connection diagram,
• 2 the supervision of an actuator according to the invention.

In the 1 can be seen the schematic diagram of a pneumatic actuator, in its housing 1 two pneumatic pistons 2 work in the opposite direction symmetrically to each other. Each of the pneumatic pistons 2 has in the example shown here a provided with a toothing piston rod 3 on, with the two piston rods 3 on the same, a counter-toothed adjusting shaft 4 Act.

The control shaft 4 in turn acts on a valve, not shown here in a system with which a flow can be throttled or shut off.

For adjustment of the control shaft 4 become the pneumatic pistons 1 in the embodiment described here via an only exemplified electrically operated 3/2 way valve 5 activated with spring return. Those skilled in the art will appreciate that other types of valves are possible.

Via this valve, the pneumatic pistons are alternatively equipped with compressed air 6 charged or with the vent 7 connected. This drives the two pneumatic pistons 1 apart or together. In case of failure of the pneumatic impingement, the pneumatic piston 1 doing so by springs 8th brought into a contracted in the example shown basic position.

Thus the procedure of the pneumatic piston 1 in the situations explained, in particular in the emergency, spring-loaded collisions not done with an undesirably high speed, the two pneumatic pistons 1 in the example shown here via connecting rods 9 with hydraulic piston 10 coupled.

These hydraulic pistons 10 move in response to the movement of the coupled with them pneumatic piston 1 in a hydraulic cylinder she enters a first workroom 11 and a second workspace 12 divide. The hydraulic cylinder or arranged in it first and second working spaces 11 and 12 are filled with a hydraulic fluid.

During a movement of the hydraulic piston 10 in the example shown here outwardly from the lying in the direction of movement, the outer second working spaces there is the existing hydraulic fluid through hydraulic connections 13 in one outside the case 1 and thus also the hydraulic cylinder lying hydraulic line 14 pressed.

In this hydraulic line 14 is an adjustable throttle valve in the example shown here 15 arranged over which the hydraulic fluid in the first working space 11 is guided back into the hydraulic cylinder. Due to the throttle valve 15 so does the movement of the hydraulic piston 10 attenuated.

In the 1 it can be seen that parallel to the two throttle valves respectively shown for the left and for the right hydraulic cylinder 15 one aperture each 16 is switched.

These apertures 16 are in contrast to the illustrated throttle valves 15 not adjustable. So you can not therefore like the two throttle valves 15 be completely closed by mistake. This is how the panels work 16 as security elements that prevent complete shutdown of the pneumatic actuator.

The flow for the panels 16 is usually at least an order of magnitude smaller than the flow of the fully opened throttle valves 15 , In normal operation, the flow through the panels 16 thus negligible. In the event of an emergency, however, they will still ensure sufficient hydraulic fluid flow for the purpose intended to guarantee the function of the actuator in the case of mistakenly completely closed throttle valves.

It should be noted that the aperture 16 Although they are permanently installed. However, they can be replaced as needed, for example, to determine different minimum speeds over different bore diameters in them.

In addition, such replaceable screens 16 are also easier to remove for their cleaning, so that even unwanted clogging during operation can be easily corrected.

In the example shown, the separately provided for each hydraulic cylinder combination of throttle valve 15 and aperture 16 and the hydraulic line connecting them and connecting them to the hydraulic cylinder 14 also in a compact connection block, eg also with NAMUR connection 18 be integrated.

This is in the 2 shown in a top view.

The two in the example shown here accordingly provided on the front of the housing blocks 18 You can also use two equalizing wires 17 be connected to each other, which further increases the reliability of the actuator outlined here. Of course, such compensation lines can also be provided if the throttle valve 15 and aperture 16 not be provided in a common block.

In the supervision you can also see that the aperture 16 simply from the terminal block 18 after opening of safety screws 19 can be removed and cleaned or replaced.

To secure the proposed throttle valves these are nuts 20 to fix, in turn, over cap nuts 21 can be countered.

LIST OF REFERENCE NUMBERS

1

casing

2

pneumatic piston

3

piston rod

4

actuating shaft

5

3/2-way valve

6

compressed air

7

vent

8th

feathers

9

Verbindugnsstangen

10

hydraulic pistons

11

first working space

12

second workspace

13

hydraulic connection

14

Hydrualikleitung

15

throttle valve

16

cover

17

compensation line

18

terminal block

19

locking screws

20

mother

21

Hutmutter

Claims (9)

Pneumatic actuator for a fitting, comprising a housing (1) in which at least one pneumatic piston (2) is arranged, which acts on a rotating actuating shaft (4) via a piston rod (3) assigned to it, the pneumatic piston (2) being provided with a hydraulic piston Damper is coupled, in which a hydraulic piston (10) in a hydraulic cylinder between a first and a second working space (11, 12) is movable, characterized in that the first and the second working space (11, 12) via an outside of the hydraulic cylinder arranged Hydraulic line (14) are connected Actuator according to Claim 1 , characterized in that in the hydraulic line (14) at least one throttle valve (15) is provided. Actuator according to Claim 2 , characterized in that the throttle valve (15) is adjustable. Actuator according to one or more of the preceding claims, characterized in that in the hydraulic line (14) at least one aperture (16) is provided. Actuator according to one or more of the preceding claims, characterized in that the diaphragm (16), although permanently installed but interchangeable Actuator according to one or more of the preceding Ansprü surface, characterized in that the diaphragm (16) parallel to the at least one throttle valve (15) in the hydraulic line (14) is arranged. Actuator according to one or more of the preceding claims, characterized in that the volume flow which flows through the diaphragm (16), at least one order of magnitude smaller than the volume flow, which flows through the opened throttle valve (15) Actuator according to one or more of the preceding claims, characterized in that the hydraulic line (14) and built-in parts (15, 16) is integrated in a connection block (18) with standard connections. Actuator according to one or more of the preceding claims, characterized in that the throttle valve (15) is to be fixed in a predetermined position and this fixation is to be secured against unintentional cancellation

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