Foil transducer and valve

Abstract

A foil transducer for a valve, including at least one firmly arranged holding part, at least one displaceable force transmission part, an electroactive foil composite structure and at least two electrodes. The electroactive foil composite structure has an actuating direction in which the electroactive foil composite structure is extended on actuation. The actuating direction lies in a plane spanned by the electroactive foil composite structure.

Claims

1. A foil transducer for a valve, serving as an actuator for the valve and comprising at least one firmly arranged holding part, at least one displaceable force transmission part, an electroactive foil composite structure and at least two electrodes, the electroactive foil composite structure having an actuating direction in which the electroactive foil composite structure is extended on actuation, and the actuating direction lying in a plane spanned by the electroactive foil composite structure; wherein a first end of the electroactive foil composite structure is held at the holding part, and a second end of the electroactive foil composite structure opposite to the first end is coupled to the force transmission part.

2. The foil transducer according to claim 1, wherein the foil transducer has a main direction of extension that coincides with the actuating direction.

3. The foil transducer according to claim 1, wherein the electrodes are arranged on opposite sides of the electroactive foil composite structure.

4. The foil transducer according to claim 3, wherein the electrodes extend over an entire surface of the respective side.

5. The foil transducer according to claim 1, wherein at least one of the first end and the second end is clamped.

6. The foil transducer according to claim 1, wherein, on at least one of the holding part and the force transmission part, electrical contacts are provided for electrically contacting the electrodes.

7. The foil transducer according to claim 1, wherein the force transmission part is formed substantially T-shaped.

8. The foil transducer according to claim 1, wherein at least one spring cooperates with the force transmission part in order to mechanically pretension the electroactive foil composite structure.

9. The foil transducer according to claim 8, wherein two springs are provided that engage opposite sides of the force transmission part with respect to the electroactive foil composite structure.

10. The foil transducer according to claim 1, wherein the foil transducer includes an actuator housing that encloses at least the electroactive foil composite structure, the holding part being firmly connected to the actuator housing or the actuator housing including the holding part.

11. The foil transducer according to claim 1, wherein a rocker is associated with the force transmission part.

12. The transducer according to claim 11, wherein an end of the rocker is associated with the force transmission part.

13. The foil transducer according to claim 1, wherein the electroactive foil composite structure comprises a flexible frame that encloses an electroactive polymer material.

14. A foil transducer for a valve, serving as an actuator for the valve and comprising at least one firmly arranged holding part, at least one displaceable force transmission part, an electroactive foil composite structure and at least two electrodes, the electroactive foil composite structure having an actuating direction in which the electroactive foil composite structure is extended on actuation, and the actuating direction lying in a plane spanned by the electroactive foil composite structure, wherein the force transmission part includes an actuating portion that extends along the actuating direction over at least an entire length of the electroactive foil composite structure.

15. The foil transducer according to claim 14, wherein the actuating portion includes an opening region through which at least one of the electroactive foil composite structure and the holding part extends.

16. A valve with a strip actuator, wherein the strip actuator is configured as a foil transducer comprising at least one firmly arranged holding part, at least one displaceable force transmission part, an electroactive foil composite structure and at least two electrodes, the electroactive foil composite structure having an actuating direction in which the electroactive foil composite structure is extended on actuation, and the actuating direction lying in a plane spanned by the electroactive foil composite structure and coinciding with an actuation direction of the displaceable force transmission part.

17. The valve according to claim 16, wherein the valve comprises a valve element formed as a flexible membrane, which the strip actuator adjusts on actuation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and properties of the present disclosure can be taken from the following description and the drawings to which reference is made. In the drawings:

(2) FIG. 1 shows a sectional representation of a valve according to the present disclosure in the closed, actuated position with a foil transducer according to a first embodiment of the present disclosure,

(3) FIG. 2 shows a sectional representation of a valve according to the present disclosure in the closed, non-actuated position with a foil transducer according to a second embodiment of the present disclosure,

(4) FIG. 3 shows a perspective representation of the valve of FIG. 2 with the actuator housing shown transparent, and

(5) FIG. 4 shows a sectional representation of a valve according to the present disclosure in the open, non-actuated position with a foil transducer according to a third embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a valve 10 that is configured as a normally open valve (NO valve). In the representation, the valve 10 however is in the closed position, because it is actuated correspondingly, as will yet be explained below.

(7) The valve 10 comprises a fluid housing 12 with a first fluid port 14 and a second fluid port 16, wherein in the illustrated embodiment a valve seat 18 is associated with the first fluid port 14, via which the valve 10 can be opened or closed correspondingly.

(8) For this purpose, the valve seat 18 cooperates with a valve element 20 that in the illustrated embodiment is formed by a flexible membrane.

(9) The valve element 20 or the flexible membrane furthermore is associated with a collecting space 22 that is provided between the valve element 20 and the valve seat 18 when the valve element 20 is in its non-actuated or open position. In the collecting space 22 a fluid can accumulate, which can flow off correspondingly via the fluid port 14 when the valve element 20 is in its corresponding position, i.e. the open position in which the valve element 20 does not rest on the valve seat 18.

(10) Alternatively, the valve element 20 can close or clear the inlet into the collecting space 22 depending on its position, in that the valve element 20 is pressed or not pressed onto the valve seat 18.

(11) In so far, the first fluid port 14 can serve as an inlet or outlet. The second fluid port 16 likewise can act as an outlet or inlet.

(12) The valve element 20 configured as a flexible membrane furthermore serves for media separation, as it separates and seals a fluid portion 24 of the valve 10 from an actuator portion 26 that comprises a foil transducer 30 configured as a strip actuator 28.

(13) The foil transducer 30 includes an actuator housing 32, wherein the valve element 20 is arranged between the actuator housing 32 and the fluid housing 12, in particular is clamped at least at the edge.

(14) Furthermore, the foil transducer 30 comprises a stationarily arranged holding part 34 coupled to the actuator housing 32 and an displaceable or movably arranged force transmission part 36 that cooperates with the valve element 20 in order to correspondingly adjust the same, so as to transfer it for example from the open position into the closed position.

(15) For actuating the valve element 20, the foil transducer 30 includes an electroactive foil composite structure 38 that in the illustrated embodiment is formed by a foil 40 of an electroactive polymer, so that the foil 40 can also be referred to as an electroactive polymer foil.

(16) The electroactive foil composite structure 38 is mechanically held with a first end 41 at a first clamping point 42 of the holding part 34 and with a second end 43 opposite to the first end 41 at a second clamping point 44 of the force transmission part 36, in particular clamped at the corresponding clamping points 42, 44.

(17) At the clamping points 42, 44 electrical contacts 46, 48 each are provided, which are electrically connected with corresponding electrodes 50, 52 of the foil transducer 30 in order to apply electric energy to the foil transducer 30.

(18) In the illustrated embodiment, the electrodes 50, 52 are arranged on opposite sides of the electroactive foil composite structure 38, i.e. of the corresponding foil 40, as can be taken from the second electrode 52 illustrated in broken lines.

(19) For reasons of clarity, the two electrodes 50, 52 here are shown only in part, wherein they can extend over the entire surface of the respective side of the electroactive foil composite structure 38, so that the electroactive polymer material of the electroactive foil composite structure 38 is arranged between the two electrodes 50, 52.

(20) The two electrodes 50, 52 accordingly are arranged in the z-direction, i.e. the direction perpendicular to the illustrated drawing plane. The z-direction corresponds to the thickness of the foil transducer 30, in particular of the electroactive foil composite structure 38, which generally is to be neglected.

(21) Furthermore, two springs 54 are provided in the illustrated embodiment, which with one end each are supported on a bearing portion 56 of the actuator housing 32. With their other end the springs 54 engage engagement points 58 of the force transmission part 36, so that the electroactive foil composite structure 38 is pretensioned via the springs 54 in that the electroactive foil composite structure 38 is pre-stretched in the y-direction.

(22) In the illustrated embodiment, the two springs 54 are arranged on opposite sides of the force transmission part 36 with respect to the electroactive foil composite structure 38, so that they substantially exert a homogeneous force on the electroactive foil composite structure 38 in order to mechanically pretension the same. Tilting of the electroactive foil composite structure 38 due to the spring force thus is effectively prevented.

(23) The springs 54 urge the force transmission part 36 towards the closed position, which is shown in FIG. 1, so that an actuating protrusion 60 of the force transmission part 36, which in the illustrated embodiment is configured as a web, rests against the valve element 20. The spring force of the springs 54 however is not so high that the valve element 20 would be pressed into the closed position.

(24) The springs 54 can also be formed by shaped springs, disk springs, rubber bands, rubber bodies or other pretensioning elements, which ensure a pretension of the foil transducer 30, in particular of the electroactive foil composite structure 38. The other pretensioning elements for example are magnetic pretensioning elements that provide a magnetic pretension of the foil transducer 30, or pretensioning elements that consist of a combination of spring elements and magnetic elements and thus provide a spring-magnetic pretension of the foil transducer 30. The magnetic pretensioning elements in particular are configured as permanent-magnetic pretensioning elements.

(25) In the following, it will be explained how the foil transducer 30 is brought from its open starting position into the closed position shown in FIG. 1.

(26) For this purpose, an electric voltage is applied to the two electrical contacts 46, 48, whereby the electrodes (electrode layers) 50, 52 of the electroactive foil composite structure 38 attract each other, so that the interposed electroactive polymer material is compressed.

(27) As the electroactive polymer material is incompressible, the reduction of the thickness (in the z-direction) leads to an increase in length of the electroactive foil composite structure 38 in the plane E spanned by the foil composite structure 38, which is defined by the x-direction and the y-direction, which corresponds to the drawing plane.

(28) In particular, the electroactive foil composite structure 38 is extended in the y-direction, which correspondingly is the actuating direction B of the electroactive foil composite structure 38 or of the foil transducer 30. In so far, this results in a movement of the foil transducer 30, in particular of the electroactive foil composite structure 38, in the plane E spanned by the foil transducer 30, which is referred to as an “in-plane” movement.

(29) The actuating direction B coincides with the main direction of extension L of the substantially rectangular and thin (as seen in the z-direction) electroactive foil composite structure 38, as can be taken from FIG. 1 in which the main direction of extension L corresponds to the center line of the electroactive foil composite structure 38 along its largest dimension.

(30) Due to the applied voltage, the electroactive foil composite structure 38 thus is extended in the plane E spanned by the foil transducer 30 in the direction of the valve element 20. The actuating protrusion 60 of the force transmission part 36 thereby transfers the valve element 20 into its closed position shown in FIG. 1, in which the valve element 20 is pressed onto the valve seat 18 in order to close the first fluid port 14 with respect to the collecting space 22.

(31) On actuation of the foil transducer 30, i.e. on transfer from the open position into the closed position, the force transmission part 36 is adjusted against the spring force of the springs 54 in order to close the valve 10.

(32) FIGS. 2 and 3 show a second embodiment of a valve 10 according to the present disclosure, which comprises a second embodiment of a strip actuator 28 or foil transducer 30.

(33) In the following, the differences to the first embodiment will be described in detail.

(34) The valve 10 according to the second embodiment is a normally closed valve (NC valve) in which the valve element 20 closes the valve seat 18 when no voltage is applied to the foil transducer 30, i.e. in the non-actuated condition, as shown in FIGS. 2 and 3.

(35) The second embodiment furthermore differs from the first embodiment to the effect that the firmly arranged holding part 34 is arranged at the end of the electroactive foil composite structure 38 facing the valve element 20, whereas the force transmission part 36 is provided at the end of the electroactive foil composite structure 38 facing away from the valve element 20.

(36) In so far, the holding part 34 and the force transmission part 36 have been switched with respect to the electroactive foil composite structure 38 as compared to the first embodiment.

(37) In the first embodiment, the force transmission part 36 has served as a lifting armature of the NO valve, whereas in the second embodiment the force transmission part 36 serves as a lifting armature of the NC valve.

(38) To transmit the movement of the force transmission part 36 to the valve element 20, the force transmission part 36 therefore comprises an actuating portion 61, as can be taken in particular from FIG. 3.

(39) The actuating portion 61 extends along the actuating direction B over at least the entire length of the electroactive foil composite structure 38 (in the y-direction). In addition, the actuating portion 61 includes an opening region 62 in which both the electroactive foil composite structure 38 and the holding part 34 are at least partly arranged, as can be taken from FIGS. 2 and 3. In so far, the actuating portion 61 comprises two webs 61a, 61b extending in the actuating direction B or in the y-direction, between which the opening region 62 is provided.

(40) The force transmission part 36 is of substantially T-shaped design, wherein the clamping point 44 of the force transmission part 36 is arranged at the crossbar of the T-shaped force transmission part 36 and the actuating portion 60 forms the web perpendicular to the crossbar.

(41) Like in the first embodiment, the force transmission part 36 includes the engagement points 58 for the springs 54, wherein the springs 54 likewise are supported on the bearing portions 56 of the actuator housing 32 in order to mechanically pretension the electroactive foil composite structure 38, i.e. to stretch the same in the actuating direction B.

(42) In case a voltage is applied via the electrical contacts 46, 48 that are arranged in the holding part 34 and in the force transmission part 36, in particular in the region of the clamping points 42, 44, the electroactive foil composite structure 38 is extended in the actuating direction B, as has been described already for the first embodiment. The force transmission part 36 thereby likewise is axially adjusted in the actuating direction B against the spring force of the springs 54, namely upwards in the orientation shown in FIGS. 2 and 3.

(43) A tensile force thereby can be exerted via the force transmission part 36, in particular the actuating portion 61, whereby the part of the force transmission part 36 resting against the valve element 20, i.e. the actuating protrusion 60, moves away from the valve element 20, so that the valve element 20 is actively transferred into the open position. This is the case in particular when the valve element 20 is coupled to the actuating protrusion 60.

(44) Alternatively, the actuating protrusion 60 can merely be brought out of contact with the valve element 20, so that the same automatically moves into the open position due to its pretension and/or the applied fluid pressure.

(45) In case the voltage at the foil transducer 30 is decreased, the electroactive foil composite structure 38 returns to its original length (as seen in the y-direction or the actuating direction B), which is shown in FIG. 2. As a result, the actuating protrusion 60 of the force transmission part 36 again presses the valve element 20 onto the valve seat 18 in order to transfer the valve 10 into its original (non-actuated) closed position.

(46) FIG. 4 shows a third embodiment of the valve 10, which differs from the first embodiment shown in FIG. 1 to the effect that the force transmission part 36 is associated with a rocker 64, in particular with an end 66 of the rocker 64 that cooperates with the valve element 20. Accordingly, the force transmission part 36 does not directly cooperate with the valve element 20 via its actuating protrusion 60, but indirectly via the rocker 64.

(47) The other end 68 of the rocker 64 is pretensioned via a compression spring 70, so that the valve 10 assumes a defined position in the non-actuated condition of the strip actuator 28 or of the foil transducer 30. This starting position is shown in FIG. 4.

(48) In the illustrated embodiment the fluid housing 12 comprises three fluid ports, two of which are first fluid ports 14 that have a corresponding valve seat 18 with which the rocker 64 is associated, in particular the ends 66, 68 of the rocker 64. In general, the fluid housing 12 in a way analogous to the embodiments according to FIGS. 1 to 3 can however also comprise only one first fluid port 14 and one second fluid port 16.

(49) The actuation of the foil transducer 30 substantially is effected in a way analogous to the embodiment described in FIG. 1, wherein an actuation of the foil transducer 30 results in a change of the rocker position of the rocker 64 from the starting position shown in FIG. 4.

(50) When a voltage is applied, the actuating protrusion 60 of the force transmission part 36 presses onto the associated end 66 of the rocker 64 due to the “in-plane” actuation in the y-direction along the actuating direction B, so that the rocker 64 correspondingly is pivoted. The end 66 of the rocker 64 then presses onto the valve element 20, so that the valve element 20 seals the associated valve seat 18. At the same time, the other valve seat 18 that is associated with the other end 68 of the rocker 64 is released due to the pivoting movement of the rocker 64.

(51) In so far, it can be adjusted via the foil transducer 30 which one of the first fluid ports 14 having a valve seat 18 is released in order to get into flow connection with the second fluid port 16.

(52) Optionally, in all embodiments it can be provided that the electroactive foil composite structure 38 comprises a flexible frame 72 that encloses the electroactive polymer material, so that the same is protected correspondingly.

(53) All embodiments are characterized by the fact that the strip actuator 28 or the foil transducer 30 expands in the actuating direction B, in case an electric voltage is applied to the electroactive foil composite structure 38. This means that the electroactive foil composite structure 38 expands in the direction in which the force transmission part 36 also is adjusted. As the actuating direction B lies in the plane that is spanned by the electroactive foil composite structure 38, it is possible that a narrow valve 10 can be created, as the moving parts required for the adjusting movement of the valve 10 move in one direction, namely the actuating direction B.

(54) In addition, all embodiments reveal that the fluid ports 14, 16 each can be arranged on one side of the fluid housing 12, whereby a narrow valve 10 is obtained, which can also be used under difficult mounting conditions.

(55) In general, the electrical contacts 46, 48 can both be arranged in the holding part 34 or both in the force transmission part 36. In particular, the arrangement of the two electrical contacts 46, 48 in the stationary holding part 34 simplifies the construction of the strip actuator or the foil transducer 30 and thus of the valve 10.

(56) The construction of the strip actuator 28 or of the foil transducer 30, i.e. the “in-plane” actuating direction B, provides for the actuator housing 32 to have a depth-width ratio (extension in the z-direction to the extension in the x-direction) between 1:15 and 1:2, in particular between 1:7 and 1:3.

(57) Accordingly, the valve 10 substantially has the same depth-width ratio as the actuator housing 32.

(58) In general, the electroactive foil composite structure 38 can also be formed by a multilayer foil composite structure that correspondingly comprises a plurality of foils of an electroactive polymer material. The individual foils are separated from each other by electrodes 50, 52 whose polarity each alternates, so that each foil of the stack is delimited by two different electrodes 50, 52, in particular over its entire surface.

(59) The respective electrodes 50, 52 accordingly rest against opposite sides of each foil, as likewise is the case with the electroactive foil composite structure 38 with only one foil according to the illustrated embodiments.

(60) The plurality of foils of the electroactive foil composite structure 38 formed as a stack can each be through-plated on a corresponding front side of the foil composite structure 38, so that all electrodes 50, 52 with the same polarity are contacted by only one associated contact 46, 48 that has the corresponding polarity.