DE102009018768B4 - Pressure medium actuated actuator with integrated quick exhaust and additional switching force impulse during venting - Google Patents

Abstract

Actuator comprising a housing (1) with piston chamber, a piston rod (2) therein with at least one attached thereto and the piston chamber wall sealed piston (3) dividing the piston chamber, on the one hand in a dense pressure chamber (4) from which one end of the Piston rod as an actuator element (5) by a piston rod seal (6) protrudes, and on the other hand in a non-dense vent space (7) having therein on the piston (3) acting prestressed compression spring (8) and a vent opening (9) in the the other end of the piston rod (2) protrudes, further with a pressure chamber (4) leading connecting channel (11) which is supplied with compressed air by means of a quick exhaust valve (12) with compressed air inlet (13), compressed air outlet (14), vent outlet (15) and a movable and elastic switching / sealing seal (16) which optionally allows the actuator upon pressurization of the compressed air inlet (13) t turns on, and otherwise on removal of the compressed air at the compressed air inlet (13) quickly turns off and additionally prevents that in case of defective actuator penetrating from the pressure chamber medium backwards penetrates into the supply line of the compressed air inlet, wherein the vent outlet (15) of the quick exhaust valve (12) the venting chamber (7) of the actuator leads, so that upon removal of the compressed air at the compressed air inlet (13), the switching / sealing seal (16) backflow of the compressed air coming from the pressure chamber (4) in the compressed air inlet (13) blocks and the venting output ( 15) opens and the resulting compressed air does not flow directly into the free air space, but in the venting chamber (7).

Description

Actuator consisting of a housing with piston chamber, a piston rod therein with at least one attached and sealed to the piston chamber wall piston dividing the piston chamber, on the one hand in a dense pressure chamber from which protrudes the one end of the piston rod as an actuator element by a piston rod seal, and on the other in a non-dense vent space with therein acting on the piston biased compression spring and a vent into which the other end of the piston rod protrudes, further supplied with a pressure chamber leading to the communication channel with compressed air by means of a quick exhaust valve with compressed air inlet, compressed air outlet, vent outlet and a Movable and elastic switching / sealing seal that allows the case that the actuator turns on when pressurized air inlet with compressed air, and otherwise when removing the compressed air at the compressed air inlet schn ell and additionally prevents that with a defective actuator penetrating from the pressure chamber medium backwards penetrates into the supply line of the compressed air inlet.

State of the art

Pressure-actuable actuators, in particular pneumatic, are used in a variety of technical areas, for example in paint shops as part of paint valves.

Paint shops require that the paints are changed frequently. Before the reloading of the spray head with another paint, a rinsing of the spray head and the supply line by means of solvent may be necessary to remove the remains of the previous paint. For rinsing, solvent and air are alternately introduced into the supply line of the spray head switched on through in the fastest possible sequence. For economic reasons, (a) a lacquer change with rinsing process should take place in as short a time as possible, and (b) a minimum amount of solvent should be consumed per rinsing process.

For applications as described above, often cage, needle or poppet valves are used. The valves usually consist of a valve block in which a valve insert is screwed pressure-tight.

The valve block includes a media room having a media input port and a media exit port with seal seat. The valve is closed if the sealing element of the valve insert is pressed onto the sealing seat of the outlet opening of the valve block.

The valve core usually consists of an integral actuator and a sealing element (sealing cone or sealing plate), which is axially fixed to the piston rod of the actuator. The actuator in turn consists of a cylindrical pneumatic housing with an axially movable piston therein which is acted upon on one side of the piston with the force of a prestressed compression spring and can be acted upon by compressed air on the other side of the piston. On the piston, a piston rod is fastened which protrudes pressure-tight from the actuator and at the end of the sealing element sits. The piston rod with the sealing element leads through the media space to the outlet opening of the valve block equipped with the sealing seat.

There are two types of media valves: Normally Closed Media Valves (in the passive state, ie not driven by compressed air, the media valve is closed), and Normal Open Media Valves (in the passive state, the media valve is open).

In the case of a normally closed media valve in the passive, non-controlled state, acts in the actuator only the preloaded compression spring and thus presses the sealing element of the piston rod against the sealing seat of the valve block, d. H. the media valve is closed. In the active, driven state, i. H. when the piston is acted upon by compressed air, the actuator piston moves against the spring force until it stops, d. H. the media valve is open and the medium can flow.

Conventional paint valves have no integrated quick exhaust. When switching to the passive depressurized state, they switch too slowly or require an additional external vent valve. Such paint valves waste Resoursen. The rinsing process takes longer than desired or more solvent is consumed than required. Lack valves that have not been active for a long time may not switch or may be delayed because the paint in the area of the piston rod seal of the actuator has become somewhat viscous. A safe "Loseisen" of the piston rod requires a stronger spring in conventional valve inserts. However, this requires larger and heavier valve inserts and consequently larger and heavier valve blocks and thus results in a smaller packing density of the valves.

task

Object of this invention is to improve the function of pressure-actuable valves of the type described above. This task is accomplished as described below. The explanation of a preferred embodiment of the invention is based on the following drawings:

1 , Actuator condition, depressurised.

2 , Actuator condition, pressurized.

• 1. In den Aktuator des Ventileinsatzes ist ein Schnellentlüftungsventil (12) integriert. Ein Schnellentlüftungsventil hat einen Eingang (13), einen Ausgang (14) und einen Entlüftungsausgang (15), und ist mit einer beweglichen elastischen Schalt/Sperrdichtung (16) versehen. Das axiale Profil der Dichtung ist asymmetrisch und ermöglicht den Durchfluss der Druckluft nur in einer Richtung, von der konvexen Fläche zur konkaven Fläche.
• 2. In den Aktuator ist ein Entlüftungsraum (7) mit einer variablen Entlüftungsdrossel (10) integriert. Die Drossel besteht z. B. aus der Entlüftungsöffnung (9) des Entlüftungsraums in den das dem Aktuatorelement (5) engegengesetzte Ende der Kolbenstange (2) des Aktuators hineinragt. Im Bereich der Entlüftungsdrossel ist die Entlüftungsöffnung z. B. konisch und die Kolbenstange z. B. abgestuft ausgeführt. Bei druckbeaufschlagtem Aktuator (2) verengt die Kolbenstange die Entlüftungsöffnung (starke Drosselung). Bei nicht-druckbeaufschlagtem Aktuator (1) verengt die Kolbenstange die Entlüftungsöffnung weniger (schwache Drosselung). Die Drosselwirkung ist somit abhängig von der Position des an der Kolbenstange (2) befestigten Kolbens (3) des Aktuators und verändert sich sobald sich der Kolben bewegt.
• 3. Im Aktuator kommt ein Stufen- bzw. Doppelkolben (3) mit unterschiedlich großen druckbeaufschlagbaren Flächen zur Anwendung. Damit ein solcher Kolben verschiebbar ist, muss der während der Kolbenbewegung sich verändernde Kolbenflächen-Zwischenraum (17) zwischen den beiden druckbeaufschlagbaren Flächen des Doppelkolbens direkt an den freien Luftraum angrenzen bzw. mindestens eine Ausgleichsöffnung (18) in den freien Luftraum haben.

3 , Shape of the switching / sealing seal during switching on.

• 1. In the actuator of the valve insert is a quick exhaust valve ( 12 ) integrated. A quick exhaust valve has an input ( 13 ), an output ( 14 ) and a vent outlet ( 15 ), and is equipped with a movable elastic switching / sealing seal ( 16 ) Mistake. The axial profile of the seal is asymmetrical and allows the flow of compressed air only in one direction, from the convex surface to the concave surface.
• 2. In the actuator is a vent space ( 7 ) with a variable vent throttle ( 10 ) integrated. The throttle is z. B. from the vent ( 9 ) of the venting space in which the the actuator element ( 5 ) opposite end of the piston rod ( 2 ) protrudes the actuator. In the area of the vent throttle, the vent z. B. conical and the piston rod z. B. executed graded. With pressurized actuator ( 2 ), the piston rod narrows the vent (heavy throttling). For non-pressurized actuator ( 1 ) the piston rod narrows the vent less (weak throttling). The throttle effect is thus dependent on the position of the piston rod ( 2 ) attached piston ( 3 ) of the actuator and changes as soon as the piston moves.
• 3. In the actuator comes a stepped or double piston ( 3 ) with different sized pressurizable surfaces for use. In order for such a piston to be displaceable, the piston surface clearance ( 17 ) are directly adjacent to the free air space between the two pressurizable surfaces of the double piston or at least one compensation opening ( 18 ) into the open air space.

Function of valve inserts of new type

When the actuator integrated in the valve insert is actuated with compressed air, the switching / blocking seal ( 16 ) on the in the vent space ( 7 ) venting outlet ( 15 ) of the quick exhaust valve ( 12 ) and closes it. Subsequently, the sealing lip of the elastic switching / sealing seal ( 16 ) from the inner wall of the vent valve (see 3 ) and gives the compressed air the way to the pressure chamber ( 3 ) of the actuator until the pressure in the pressure chamber is equal to that at the pressure input ( 13 ) pending pressure. Meanwhile, the pressure in the pressure chamber increases and switches the actuator to the active state (switched on); at the same time the compensation opening ( 18 ) of the piston surface clearance ( 17 ) of the stepped or double piston and the vent throttle ( 10 ) of the venting space ( 7 ) a pressure equalization to the free air space. The shift / locking seal ( 16 ) resumes its original normal shape due to its elasticity and lies down against the inner wall of the quick-release valve ( 12 ) at.

When depressurizing the actuator integrated in the valve insert, the compressed air is forced out of the pressure chamber ( 4 ) of the actuator back into the quick exhaust valve ( 12 ) and thereby pushes the shift / locking seal ( 16 ) from the vent outlet ( 15 ) of the vent valve backwards against the air inlet ( 13 ) and closes or blocks this. The venting outlet ( 14 ), so that the compressed air in the venting space ( 7 ) of the actuator flows and there due to the initially closed bleeder throttle ( 10 ) for the time being. Because the piston surface in the venting chamber ( 7 ) is larger than in the pressure chamber ( 4 ), arises at pressure equalization in these two spaces, on the piston surface of the venting chamber, a larger force than the force remaining on the piston surface of the pressure chamber. The resulting switching force pulse acts in addition to the compression spring and supports the loose iron one possibly in the area of the piston rod seal ( 6 ) sluggish piston rod of the actuator element ( 5 ). After the piston or piston rod starts to move, the force of the compression spring alone is sufficient to switch the actuator to the passive state (off). This opens the vent throttle ( 10 ) of the venting space continuously. At the same time, the compensation opening ( 18 ) of the piston surface clearance ( 17 ) of the stepped or double piston and the vent throttle ( 10 ) of the venting space ( 7 ) a pressure equalization to the free air space.

With appropriate dimensioning of the volumes, ie pressure chamber ( 4 ) with a relatively large volume and venting space ( 7 ) with a relatively small volume and relatively high pressure of the compressed air and corresponding throttling characteristic of the vent throttle ( 10 ) works an actuator of this kind without pressure spring ( 8th ). Such actuators are used in special applications in which the usual types of actuators can not be used, for. B. in microtechnology, in special slide valves, or similar

Advantages of valve inserts of new type

Valve inserts of this type have the advantage that they achieve a much faster switching time when venting. In this case, part of the energy from the escaping compressed air is used around a possibly difficult to push piston rod ( 2 ) of the actuator. Before the piston ( 3 ) and the attached thereto piston rod ( 2 ) start to move, is the opening of the vent throttle ( 10 ) relatively tight. During switching off or depressurized switching of the actuator thus come the vent space ( 7 ) and the pressure chamber ( 4 ) briefly to the same pressure. Because the piston area in the vent space is greater than the piston area in the pressure chamber, arises on the vent side surface of the stepped or double piston ( 3 ) more pressure than on the pressure chamber side surface. This excess force acts in addition to the force of the preloaded compression spring and ensures a safe and faster switching of the valve when venting. After the piston and attached piston rod begin to move, the throttling action decreases and the actuator is unthrottled and rapidly vented to the atmosphere. The compressed air thus does not escape unnecessarily slowly over the control valve, which is often several meters away in the pneumatic cabinet.

Valve inserts of this new type have the further advantage that in case of leakage of the piston seal ( 6 ) of the integrated actuator, the medium to be processed at most into the pressure chamber ( 4 ) of the actuator can flow. In this case, the medium would only through the vent valve ( 12 ), the ventilation space ( 7 ) as well as through the vent throttle ( 10 ) flow away. A connected with considerable repair and cleaning costs rearward penetration of the paint in the control line of the pneumatic, in the worst case up to the control valve in the pneumatic cabinet is due to the switching / sealing seal ( 16 ) prevented.

Valve inserts of the new type have the further advantage that they are not much larger than conventional valve inserts. Thus, they can be mounted in the same packing density side by side in a valve block or manifold block. Only the additional force pulse of escaping compressed air allows these compact, safe and fast paint valves.

LIST OF REFERENCE NUMBERS

1

casing

2

piston rod

3

piston

4

pressure chamber

5

actuator

6

Piston rod seal

7

vent space

8th

compression spring

9

vent

10

vent throttle

11

connecting channel

12

Quick exhaust valve

13

Compressed air inlet

14

Compressed air outlet

15

bleed outlet

16

Switch / barrier seal

17

Piston areas gap

18

compensation opening

19

compensation opening

Claims (11)

Actuator consisting of a housing ( 1 ) with piston chamber, a piston rod therein ( 2 ) with at least one attached thereto and sealed to the piston chamber wall piston ( 3 ) which divides the piston chamber, on the one hand into a dense pressure chamber ( 4 ) from the one end of the piston rod as Aktuatorelement ( 5 ) by a piston rod seal ( 6 ) and on the other hand into a non-dense vent space ( 7 ) with an on the piston ( 3 ) acting prestressed compression spring ( 8th ) and a vent ( 9 ) into which the other end of the piston rod ( 2 ), further with a pressure chamber ( 4 ) leading connection channel ( 11 ) which is supplied with compressed air by means of a quick exhaust valve ( 12 ) with compressed air inlet ( 13 ), Compressed air outlet ( 14 ), Bleed outlet ( 15 ) and a movable and elastic switching / sealing seal ( 16 ), which allows the actuator to be acted upon when the compressed air inlet ( 13 ) with compressed air, and otherwise when removing the compressed air at the compressed air inlet ( 13 ) quickly switches off and additionally prevents that when a defective actuator penetrates from the pressure chamber medium backward penetrates into the supply line of the compressed air inlet, wherein the vent outlet ( 15 ) of the quick exhaust valve ( 12 ) in the vent space ( 7 ) of the actuator, so that when removing the compressed air at the compressed air inlet ( 13 ), the shift / locking seal ( 16 ) a backflow from the pressure chamber ( 4 ) coming compressed air into the compressed air inlet ( 13 ) as well as the venting outlet ( 15 ) and the resulting compressed air does not flow directly into the free air space, but into the vent space ( 7 ). Actuator according to claim 1, characterized in that the vent ( 9 ) of the venting space ( 7 ) with a variable vent throttle ( 10 ), which at the start of the vent, immediately after removal of the control pressure at the compressed air inlet ( 13 ), has a high throttle resistance, and whose throttle resistance with progressive movement of the piston ( 3 ) and the piston rod attached thereto ( 2 ) decreases. Actuator according to claim 2, characterized in that the piston ( 3 ) is a stepped or double piston and the to the vent space ( 7 ) adjacent piston surface is larger than that to the pressure chamber ( 4 ) adjacent piston surface. Actuator according to claim 2, characterized in that the variable bleed throttle ( 10 ) is formed from the vent ( 9 ) and from the actuator element (FIG. 5 ) opposite end of the piston rod ( 2 ), wherein in the area of the vent throttle ( 10 ) the vent ( 9 ) and / or the piston rod ( 2 ) can be stepped or conical. Actuator according to claim 2, characterized in that the throttle resistance of the vent throttle ( 10 ) while switching is dependent on the position of the piston ( 3 ) or attached to the piston rod ( 2 ). Actuator according to claim 3, characterized in that the piston surface space formed by the stepped or double piston ( 17 ) via the compensation opening ( 19 ) vented into the free air space. Actuator according to claim 3, characterized in that the piston surface space formed by the stepped or double piston ( 17 ) with the free air space via a radial compensation opening ( 19 ). Actuator according to claim 1, characterized in that the quick exhaust valve ( 12 ) in the housing ( 1 ) of the actuator is integrated. Actuator according to claim 1, characterized in that the venting outlet ( 15 ) of the integrated quick exhaust valve ( 12 ) directly into a variably throttled venting space ( 7 ) leads. Actuator according to claim 1, characterized in that the quick exhaust valve ( 12 ) in the actuator in the immediate vicinity of the venting space ( 7 ) as well as at the pressure room ( 3 ) is integrated. Method for switching an actuator according to claims 1 and 2, characterized in that the fast and safe switching due to the interaction of the integrated in the actuator housing quick exhaust valve ( 12 ) and by the also integrated ventilation throttle ( 10 ) caused short-term pressure build-up in the venting space ( 7 ) while venting.

Images