DE20116515U1 - Actuator and valve equipped with it - Google Patents

Description

G 19669 - lemh August 14, 2001

FESTO AG & Co. 73734 Esslinaen Actuator and valve equipped with it

The invention relates to an actuator for selectively positioning and removing an active surface in or from an active position. The invention further relates to a valve equipped with such an actuator.

DE 37 38 630 C2 describes several types of valves in which the valve element is designed as a piezoelectric bending actuator. In one case, an effective surface is arranged on the side of the bending actuator, which can be brought closer or closer to a nozzle in order to create a greater or lesser flow resistance depending on the respective effective position. Due to the relatively low forces of the bending actuator, however, only relatively small nozzle nominal widths can be controlled. In addition, the bending actuator must achieve a minimum stroke above the nozzle opening in order to enable the largest possible flow cross-section when required.

In another embodiment of the known valve, the effective surface is located on one end of the bending actuator. The bending movement therefore no longer runs in the outflow direction of the fluid, but rather perpendicular to it. In this way, when

When the valve is in the active position, a higher counterforce can be built up with respect to the outflowing fluid. However, due to the movement play that must be ensured, this design does not make it possible to seal a valve opening tightly in the active position.

The object of the present invention is to create an actuator whose effective surface can absorb high forces while allowing good positioning. Furthermore, a valve equipped with such an actuator is to be proposed.

This object is achieved with an actuator for selectively positioning and removing an active surface in or from an active position, which is characterized by a design as a combined bending and translation actuator for generating both a linear movement and a pivoting movement of the active surface running transversely to the linear movement.

To achieve the object, a valve is further provided whose valve member is formed by an actuator of the aforementioned structure.

The design of the actuator as a combined bending and translation actuator enables a very flexible positioning of the active surface. For example, it is possible to remove the active surface from the active position by first moving it in a linear direction and then pivoting it transversely to it. Such an operating behavior can be

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particularly advantageous in connection with valves used for fluid control. For example, the active position can be defined by the active surface covering a valve opening and facing the outflowing fluid, whereby it can cause the valve opening to close, particularly in the manner of a seat valve. The translation actuator allows high holding forces to be applied. To release the valve opening, the active surface can first be lifted further away from the valve opening by generating a linear movement, and then pivoted away to the side by a pivoting movement so that the valve opening is completely released. In summary, this is an actuator which, when controlled accordingly, enables both high actuating forces and a wide variety of movement patterns of the active surface.

Advantageous further developments of the invention emerge from the subclaims.

In principle, the actuator can be designed so that the linear movement and the swivel movement take place one after the other. However, a design that allows the linear movement and swivel movement to take place in parallel is seen as more advantageous, which generally makes it possible to move the active surface between two positions in a shorter time.

The actuator preferably has a fastening end for fixed fixation and an opposite,

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working end equipped with the effective surface. In connection with a valve, the fastening end can be fixed to the valve housing.

In a preferred embodiment, the actuator has at least two actuator sections that are motion-coupled to one another, because one actuator section is formed by a translation drive that causes the linear movement and another actuator section is formed by a bending drive that causes the pivoting movement. In particular, it is possible to connect the two actuator sections in series. Depending on the embodiment, the fastening end of the actuator can be located on the translation drive or on the bending drive, with the active surface being provided on the other drive.

The actuator can be designed as a rod, column or strip. It preferably has a longitudinal extension, with the active surface being placed in particular on one end face and with the linear movement direction coinciding with the direction of the longitudinal extension.

The actuator is preferably a piezo actuator. Both the translation drive and the bending drive can be based on piezoelectric functionality. For the translation drive, a structure as a piezoelectric stack translator is recommended, which generally only allows a small stroke but can generate high actuating forces.

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For the bending drive, a design with at least one piezoelectric bending element, for example in a bimorph design, is recommended.

A further advantageous design option for the bending drive consists in the combination of two piezoelectric stack translators connected in parallel, which can be operated simultaneously in opposite directions to generate tensile forces and/or compressive forces.

As already mentioned, the actuator is particularly recommended as a valve element in a valve used for fluid control, whereby the active surface is intended to close a valve opening in the active position.

The invention is explained in more detail below with reference to the accompanying drawing. Figures 1 to 5 each show, in a schematic representation, a side view of various designs of the actuator according to the invention in an advantageous embodiment as a component of a valve used for fluid control.

Figures 1 to 5 each show a section of a valve, designated in its entirety by reference number 1, which is preferably operated purely piezoelectrically, so that it can also be referred to as a piezo valve. However, other types of operation are also possible.

The valve 1 has a valve housing 2 which defines at least one valve chamber 3 in which a valve member 4 is arranged.

The valve member 4 has a movable control section 5 which defines an effective area 6. This effective area

6 can optionally be positioned in an effective position 7 or removed from this effective position 7.

In the embodiment, the active position 7 is a closed position in which the active surface 6 closes a valve opening 8 of the valve 1. The valve 1 is designed in particular as a seat valve and has a valve seat 12 which surrounds the valve opening 8 and against which the active surface 6 rests in a sealing manner in the active position 7. This prevents a fluid from flowing into the valve chamber 3 through the valve opening 8.

By appropriate actuation of the valve member 4, the effective surface 6 can also be moved in one or more positions

7. One possible further position of the active surface 6 is shown in Figures 1 and 2 and is referred to as the release position 13. The active surface 6 is here lifted from the valve seat 12 and releases the valve opening 8 so that a fluid is able to flow through the valve opening 8 into the valve chamber 3.

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The valve opening 8 belongs to a first fluid channel 14 which passes through the wall of the valve housing 2. It can be connected to an external fluid source (not shown in detail).

In a preferred embodiment of the valve 1 as a 2/2-way valve, at least one further fluid channel (not shown in detail) leads into the valve chamber 3, which can be connected to a consumer to be controlled, for example to a fluidically actuated drive. Depending on the position of the valve member 4, a fluid connection between the fluid source and the drive can then be established or interrupted.

However, valve 1 can also have a different functionality and be a 3/2-way valve, for example. It then contains at least one further valve opening to be controlled, to which a further valve element of the type described here is expediently assigned.

The fluid to be controlled can be a gaseous fluid, such as compressed air, or a hydraulic fluid, such as water or oil.

In all embodiments, the valve member 4 consists of an actuator equipped with the effective surface 6 in the form of a combined bending and translation actuator 15. This is capable of both a

Linear movement 16 as well as a pivoting movement 17 of the active surface 6 running transversely to the linear movement 16.

It is advantageously possible to carry out the linear movement 16 and the swivel movement 17 in a superimposed manner, so that the movement path of the active surface 6 can be specified in a very variable manner. However, it is also possible to carry out the linear movement 16 and the swivel movement 17 in succession. The further description is based on such a sequence of movements, although, as mentioned, it is also possible to superimpose the movements at least in phases.

What all embodiments have in common is that the combined bending and translation actuator 15 has a longitudinal extension. One of its front ends is a fastening end 18, with which it is fixed to the housing. Starting from the fastening end 18, the bending and translation actuator 15 preferably extends freely cantilevered and without further fastening to its opposite front end, on which the active surface 6 is provided and which is referred to as the working end 22 that can be moved together with the active surface 6.

All embodiments also have in common that the bending and translation actuator 15 has two actuator sections 23a, 23b which are coupled to one another in terms of movement and which

the direction of the longitudinal extension of the bending and translation actuator 15 are arranged one after the other, so that one can speak of a series connection. The one actuator section 23a is formed by a translation drive 24 causing the linear movement 16, the other actuator section 23b by a bending drive 25 causing the pivoting movement 17. The linear movement 16 runs in the direction of the longitudinal extension of the bending and translation actuator 15.

In the embodiments of Figures 1 and 3 to 5, the fastening end 18 is located on the bending drive 25 and the active surface 6 is located on the translation drive 24. In the embodiment of Figure 2, the arrangement is reversed.

What all embodiments have in common is that both the translation drive 24 and the bending drive 25 are formed by a piezoelectric drive. To actuate a respective drive, a more or less high voltage is applied, which results in the desired deflection or translation due to a deformation of the existing piezoelectric material. In principle, however, it would also be possible to use other drive principles, for example those based on fluidic actuation force.

In the embodiments of Figures 1 and 2, the bending and translation actuator 15 has a rod, column or

strip-shaped design. The two actuator sections 23a, 23b are arranged one after the other in the longitudinal direction of the bending and translation actuator 15 and are placed directly next to one another. In the embodiment of Figure 1, the rear end 26a of the translation drive 24 opposite the working end 22 is firmly connected to the front end 26b of the bending drive 25 opposite the fastening end 18. In the embodiment of Figure 2, the front end 27a of the translation drive 24 opposite the fastening end 18 is firmly connected to the rear end 27b of the bending drive 25 opposite the working end 22.

In the embodiments of Figures 1 and 2, the translation drive 24 is formed by a piezoelectric stack translator. The bending drive 25 consists of a piezoelectric bending element.

The length dimensions of the actuator sections 23a, 23b are expediently selected such that in the electrically unexcited state and with the active surface 6 in the active position 7, an axial pressure force is built up with which the active surface 6 is mechanically prestressed against the valve seat 12. The bending and translation actuator 15 is practically supported with its fastening end 18 and its working end 22 on the valve housing 2.

In order to move the active surface 6 from this active position 7 into the release position 13, the translation drive 24 is first activated. This leads to a shortening of the translation drive 24 and consequently to a lifting of the active surface 6 from the valve seat 12. The pivoting movement 17 is then caused by activating the bending drive 25, during which the active surface 6 is moved from the raised position, which was previously axially opposite the valve opening 8, into the sideways pivoted release position 13 shown in Figures 1 and 2. The valve opening 8 is now maximally released.

If the valve opening 8 is to be closed again, the movement sequences described take place in reverse order. First, the bending drive 25 moves the effective surface 6 back into the position axially opposite the valve opening, whereby there is still no contact with the valve seat 12 because the translation drive 24 is still shortened in length. Only then is a linear extension movement of the effective surface 6 caused by the corresponding actuation of the translation drive 24 until the latter comes to rest on the valve seat 12.

It is obvious that with such a bending and translation actuator 15, high closing forces can be generated, since the fluid forces acting on the effective surface 6 in the area of the valve opening 8 are active in the longitudinal direction of the bending and translation actuator 15, in which the actuator has a very

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has high pressure stiffness. It is also clear that due to the possible pivoting movement, an optimal release of the valve opening 8 is possible when required in order to allow an undisturbed fluid flow.

The embodiments of Figures 3, 4 and 5 have in common that all actuator sections 23a, 23b are constructed from stack translators.

The translation drive 24 here consists of a single stack translator, as is also the case in the embodiment of Figure 1. The bending drive 25, on the other hand, consists of two piezoelectric stack translators 28a, 28b connected in parallel and arranged side by side. These are each attached to the housing at one end and carry the translation drive 24 at the other end. The two stack translators 28a, 28b are expediently pre-tensioned in the longitudinal direction by suitable tensioning means, in particular with the same force.

In the embodiments of Figures 3 and 4, the two stack translators 28a, 28b are relatively far apart from one another. There is no longitudinal contact. At the front ends 32 opposite the fastening end 18, the stack translators 28a, 28b are connected to one another by a rigid connecting part 33, in particular in a yoke-like manner. The translation drive 24 is held centrally between the two front ends 32 on the connecting part 33.

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The stack translators 28a, 28b are now designed in such a way that by applying a correspondingly polarized voltage, either an extension or a shortening can be brought about. Furthermore, an actuation is possible in which an opposite activation takes place at the same time, so that when one stack translator is shortened, the other stack translator is simultaneously extended. As a result, the bending and translation actuator 15 as a whole can be tilted sideways, which results in the aforementioned pivoting movement 17 of the active surface 6.

The embodiment of Figure 4 shows an example of a possible embodiment of the above-mentioned clamping means in the form of an elongated clamping element 34 which is arranged between the two stack translators 28a, 28b and extends there, preferably in a direction parallel to the stack translators 28a, 28b, between the connecting part 33 and that region of the valve housing 2 to which the fastening end 18 is also anchored.

The clamping element 34 is sufficiently rigid to absorb the forces applied by the translation drive 24, but at the same time has sufficient material elasticity to enable lateral deflection to maintain the pivoting movement 17. The clamping element 34 engages both end faces of the stack translators 28a, 28b and applies a compressive stress to them.

The structure of the embodiment according to Figure 5 corresponds in principle to that of Figure 3, but here the two stack translators 28a, 28b are combined to form a single structural unit, so that particularly compact dimensions are possible. In Figures 3 and 5 the clamping means are integrated and therefore not visible.

Claims (21)

1. Actuator for selectively positioning and removing an active surface ( 6 ) in or from an active position, characterized by a design as a combined bending and translation actuator ( 15 ) for generating both a linear movement ( 16 ) and a pivoting movement ( 17 ) of the active surface ( 6 ) running transversely to the linear movement ( 16 ). 2. Actuator according to claim 1, characterized in that the active surface ( 6 ) can be driven to a superimposed linear movement ( 16 ) and pivoting movement ( 17 ). 3. Actuator according to claim 1 or 2, characterized by a fastening end ( 18 ) serving for stationary fixation and an opposite working end ( 22 ) of the bending and translation actuator ( 15 ) equipped with the active surface ( 6 ). 4. Actuator according to one of claims 1 to 3, characterized by at least two actuator sections ( 23a , 23b ) of the bending and translation actuator ( 15 ) which are coupled to one another in terms of movement, wherein one actuator section ( 23a ) is formed by a translation drive ( 24 ) causing the linear movement ( 16 ) and another actuator section ( 23b ) is formed by a bending drive ( 25 ) causing the pivoting movement ( 17 ). 5. Actuator according to claim 4 in conjunction with claim 3, characterized in that the fastening end ( 18 ) is arranged on one and the active surface ( 6 ) on the other actuator section ( 23a , 23b ). 6. Actuator according to claim 4 or 5, characterized by a series connection of the two actuator sections ( 23 a, 23 b). 7. Actuator according to one of claims 4 to 6, characterized in that the active surface ( 6 ) is arranged on the translation drive ( 24 ). 8. Actuator according to one of claims 4 to 7, characterized in that the active surface ( 6 ) is arranged on the bending drive ( 25 ). 9. Actuator according to one of claims 4 to 8, characterized in that the translation drive ( 24 ) contains at least one piezoelectric stack translator. 10. Actuator according to one of claims 4 to 9, characterized in that the bending drive ( 25 ) contains at least one piezoelectric bending element. 11. Actuator according to one of claims 4 to 10, characterized in that the bending drive ( 25 ) contains two piezoelectric stack translators ( 28 a, 28 b) connected in parallel and operable simultaneously in opposite directions to generate expediently both tensile forces and compressive forces. 12. Actuator according to claim 1, characterized in that the two stack translators ( 28 a, 28 b) are prestressed in the longitudinal direction by tensioning means ( 34 ). 13. Actuator according to one of claims 1 to 12, characterized by a rod-, column- or strip-shaped design of the bending and translation actuator ( 15 ). 14. Actuator according to one of claims 1 to 13, characterized by a longitudinal extension with an active surface ( 6 ) arranged on one end face, wherein the linear movement direction coincides with the direction of the longitudinal extension. 15. Actuator according to one of claims 1 to 14, characterized by a design as a piezo actuator. 16. Actuator according to one of claims 1 to 15, characterized by a design of the bending and translation actuator ( 15 ) as a valve member ( 4 ) in a valve ( 1 ) used for fluid control, wherein the active surface ( 6 ) can be provided in order to close a valve opening ( 8 ) in the active position. 17. Actuator according to claim 16, characterized in that the valve ( 1 ) is a piezo valve. 18. Valve with at least one valve member ( 4 ) formed by an actuator according to one of claims 1 to 17. 19. Valve according to claim 18, characterized in that the active surface ( 6 ) in the active position ( 7 ) can close a valve opening ( 8 ). 20. Valve according to claim 19, characterized in that the valve opening ( 8 ) has a valve seat ( 12 ) against which the active surface ( 6 ) can rest in a sealing manner in the active position ( 7 ). 21. Valve according to one of claims 18 to 20 in a configuration as a piezo valve.