WO2009006365A1

WO2009006365A1 - Continuous folded actuator

Info

Publication number: WO2009006365A1
Application number: PCT/US2008/068707
Authority: WO
Inventors: Dickory Rudduck; Sigurd Anthony Ii Nelson
Original assignee: Telezygology, Inc.
Priority date: 2007-06-29
Filing date: 2008-06-30
Publication date: 2009-01-08

Abstract

This invention relates to an actuator having a continuous, elongated element with the ability to selectively activate portions of the element to produce accumulated movement. More specifically, it relates to an actuator compπsing an elongated element having a mateπal adapted to contract when activated, the elongated element having a first portion disposed in a first direction and a second portion disposed in a second direction being, different from the first direction means for selectively activating the elongated element by way of the first portion of the elongated element, the second portion of the elongated element or both the first portion and second portions of the elongated element and an output element adapted for movement upon activation of any of the first portion of the elongated element the second portion of the elongated element or both portions of the elongated element.

Description

Continuous Folded Actuator FIELD OF THE INVENTION

This invention relates to an actuator capable of selective activation. More specifically it relates to an actuator having a continuous, elongated element with the ability to selectively activate portions of the element to produce accumulated movement.

BACKGROUND OF THE INVENTION

Actuators utilizing smart materials have been gaining popularity over recent years. There is an extremely wide range of applications for such actuators ranging from uses on aircraft, automobiles, computers, and personal home use. While the uses of smart materials in actuators are seemingly endless, there are some drawbacks. Smart materials tend to have a limited useful lifespan, may be prone to breakage, and can only contract consistently about 3%. Therefore there is a demand to improve the lifespan on the material and to amplify the movement achieved by contraction.

Current developments in this field have resulted in actuators that do work to overcome some of the above problems. Examples of such actuators are seen in U.S Patent Nos. 6,762,515 and 6,326,707 and in U.S. Publication No. 20040256920. The documents disclose linear actuators utilizing many strips or wire of SMA material crimped onto links to provide for amplified movement and a longer useful lifespan. While these actuators have attempted to solve some problems, they are difficult and expensive to manufacture. Each actuator comprises many parts that need to be assembled in a lengthy assembly process. This causes the actuator to be costly in both time and money. As such there is a demand to reduce the number of parts and steps in manufacture. This invention aims to solve that problem while also overcoming problems in improved lifespan and amplified movement.

SUMMARY OF THE INVENTION This invention relates to an actuator comprising: - an elongated element having a material adapted to contract when activated, the elongated element having a first portion disposed in a first direction and a second portion disposed in a second direction being different from the first direction;

- means for selectively activating the elongated element by way of the first portion of the elongated element, the second portion of the elongated element or both the first portion and second portions of the elongated element; and

- an output element adapted for movement upon activation of any of the first portion of the elongated element, the second portion of the elongated element or both portions of the elongated element.

This material adapted to contract when activated is preferably shape memory alloy (SMA) wire or strips. Shape memory alloys are known and are usually made predominantly or wholly of titanium and nickel. They may also include other material, such as aluminium, zinc and copper. A shape memory alloy is capable of adopting one shape below a predetermined transition temperature and changing to a second shape once its temperature exceeds the transition temperature. Conversely, when the shape memory alloy cools below the transition temperature, it is capable of adopting the first shape again. In connection with the various aspects of the present invention, the shape memory alloy contracts when heated in situ. Shape memory alloy wire currently available, such as that sold under the trade mark Nitinol, is capable of contracting by about 3% when activated by heating.

Activation of the material adapted to contract when activated is preferably achieved through electrical resistance heating, with a wire feed to the assembly.

Activation of the shape memory alloy wire can be initiated from a central location, using the wiring system of, for example, a security system. It is also within the scope of this invention that the activation is initiated by remote means, such as a hand held tool operating through the use of any suitable form of energy, including microwave, electric magnetic, sonic, infra-red, radio frequency and so on.

The scope of the invention in its various aspects is not necessarily limited to the use of shape memory alloy. Other material may also be useful. Also, while activation may take place through heating, other means of activation may be suitable and are within the scope of this invention. One skilled in the art will recognize that the SMA material may include multiple portions. For example, there may be a third portion disposed in the first direction, a fourth portion disposed in the second direction, a fifth portion disposed in the first direction, a sixth portion in the second direction and so on and so forth. There need not be a limit on the number of portions included within the actuator. These portions may be in equal or unequal length to each other, may be arranged in increasing or decreasing length, may be parallel or in a circle with each other, etc.

The SMA material is to be fixed at one end and attached to the output element at the other end and is maintained with the activation means and output element within a supporting structure. This supporting structure may encompass a variety of shapes. It may rectangular, cubed, an annular cylinder, or any other curved three-dimensional shape. This supporting structure may deformable and comprise ribs to provide added buckling support during activation. The supporting structure includes means for separating the portions of the elongated element. These means for separating a designed to fit within the shape of the supporting structure and provide a support path for the continuous SMA element. Other embodiments may include a scenario whereby the supporting structure allows the portions of the SMA element to be slidably attached other portions along the structure. The aim of this invention is to selectively heat portions of the SMA element to create movement. The means for activation is included in a circuit board having bridging tracks. The bridging tracks prevent activation at any portion along the elongated element. One skilled in the art will recognize that the bridging tracks need not necessarily comprise a track but can also be a wire or be a gold plated element of the el ongated element.

As current is applied to the SMA material, portions of the SMA element will be activated and contract. This action causes movement of the output element that is amplified as each activated portion is contracted. One skilled in the art will recognize that portions can be activated incrementally or can be activated all once. To selectively activate, the bridging tracks are employed to compress portions of the continuous SMA element. This compression causes the compressed portion to short circuit and remain inactivated. This action allows portions of the continuous SMA material to activate and other portions to remain in their steady state, inactive position. A re-biasing means can be utilized, such as a leaf re-bias spring, to bring the activated portions back to their steady state position.

The activating means may also comprise a peltier heat pump which can aid in the heating and/or cooling of the SMA material. Other advantages and aspects of the present invention will become apparent upon reading the following description of the drawings and the detailed description of a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 details the actuator in its inactive state; the output shaft in its steady state position.

FIG. 2 details the actuator in its active position; the output shaft in an outward position.

FIG. 3 details the actuator in its inactive position with the circuit board and bridging track detail. FIG. 4 details the actuator in its active position with the circuit board and bridging track detail.

FIG. 5 depicts the circuit board detail.

FIG. 6 depicts the actuator whereby the SMA material is slidably attached and in its steady state position. FIG. 7 depicts the actuator whereby the SMA material is slidably attached and in its activated position.

FIG. 8 details the actuator in its inactive position with the circuit board and bridging track detail. FIG. 9 details the actuator in its active position with the circuit board and bridging track detail.

FIG. 10 is a cross-sectional view of the actuator detailing the SMA material.

FIG. 11 depicts an annular embodiment of the actuator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of this actuator capable of selective heating 2 comprises a continuous, elongated element 4 having material adapted to contract when activated, a means for selectively activating 10 the elongated element 4, and an output element 6. The elongated element 4 has a first portion 4a opposed in a first direction and a second portion 4b disposed in a second direction being different from the first direction. It is preferred if there are numerous portions such as a third portion 4c of the elongated element disposed in the first direction and a fourth portion 4b disposed in the second direction. This can repeat in as many portions as desired.

FIGS. 1-4 depict a preferred embodiment whereby the elongated element 4 is attached at one end of the output shaft 6 and fixed at the other. FIGS. 6-9 depict another preferred embodiment whereby the elongated element 4 may be attached at one end of the output shaft 6 and fixed at the other. However, the main feature of the actuator 2 in FIGS. 6-9 is that each portion is slidably attached to the other portions. The first portion 4a is joined with the second portion 4b and slidably attached to the third portion 4c which is joined with the fourth portion 4c. This can repeat in as many portions as desired.

Preferred embodiments will include a means for actuation 10 having a circuit board 14 and bridging tracks 12. The bridging tracks 12 prevent activation at any portion along the elongated element 4. As current is applied to the elongated element 4, portions of the elongated element 4 will be activated and contract. This action causes movement along the elongated element 4 and thereby movement of the output element 6 that is amplified as each activated portion is contracted. It is desired that the portions can be activated incrementally or can be activated all once. To selectively activate, the bridging tracks 12 are employed to compress portions of the elongated element 4. This compression causes the compressed portion to short circuit and remain inactivated. This action allows portions of the elongated element 4 to activate and other portions to remain in their steady state, inactive position. In FIGS. 1-4 the first portion 4a is shown to be inactivated and the second portion 4b is shown to be activated. In FIGS. 6-9 the first portion 4a is shown to be activated and the second portion 4b is shown to be inactivated. A re-bias means (not shown) can be included to re-bias the elongated element 4 after activation.

The elongated element 4, the activating means 10, and the output element 6 are to be within a supporting structure 16. This supporting structure 16 can be in the shape of a rectangle, cube, annular cylinder, can be parallelpiped, or in any other curved three- dimensional shape. This supporting structure 16 can also be deformable. The supporting structure 16 preferably includes means for separating each portion 18.

The invention may be described in terms of claims that can assist the skilled reader in understanding the various aspects and preferments of the invention. It will be appreciated by those skilled in the art that many modifications and variations may be made to the embodiments described herein without departing from the spirit and scope of the invention. Industrial Applicability

As will be appreciated by those skilled in the various arts, this invention disclosed herein is not limited to the examples set our above and has wide application in many areas. This invention represents a significant advance in the art of bending actuators.

Claims

ClaimsWhat is claimed is:

1. An actuator capable of selective activation including:

an elongated element having a material adapted to contract when activated, the elongated element having a first portion disposed in a first direction and a second portion disposed in a second direction being different from the first direction;

means for selectively activating the elongated element by way of the first portion of the elongated element, the second portion of the elongated element or both the first and second portions of the elongated element; and

an output element adapted for movement upon activation of any of the first portion of the elongated element, the second portion of the elongated element or both portions of the elongated element.

2. The actuator of claim 1 , which includes a third portion of the elongated element disposed in the first direction and a fourth portion disposed in the second direction, the first, second, third and fourth portions forming a continuous folded elongated element.

3. The actuator of claim 2, a fifth portion disposed on the first direction and a sixth portion disposed in the second direction, the first, second, third, fourth, fifth and sixth portions forming a continuous folded elongated element.

4. The actuator of claim 3, wherein the elongated element is attached at the one end to the output element and fixed at the other end.

5. The actuator of claim 4, wherein each portion may be slidably attached to the other portions.

6. The actuator of claim 4, wherein said means for activation of the elongated element is included in a circuit board having bridging tracks.

7. The actuator of claim 6, wherein said bridging tracks prevent activation at any portion along the elongated element.

8. The actuator of claim 6, wherein activation of more than one portion is adapted to accumulate to provide an increased movement of the output element.

9. The actuator of claim 8, which includes means for rebiasing each portion of the elongated element after activation.

10. The actuator of claim 9, wherein the rebiasing means is a leaf spring.

11. The actuator of claim 6 which includes a structure to support the elongated element, the activating means and the output element.

12. The actuator of claim 11 , wherein the supporting structure is a rectangular parallelepiped, a cube, an annular cylinder or another curved three dimensional shape.

13. The actuator of claim 11 , wherein the supporting structure is deformable.

14. The actuator claim 11 wherein the supporting structure includes means for separating the portions of the elongated element.

15. The actuator of claim 1 , wherein the activating means includes a pelti er heat pump.

16. The actuator claim 1 , wherein the elongated element is shape memory alloy wire.