Positioning and locking mechanisms and articles that employ the same
Disclosed herein is a locking mechanism for positioning or locking an article comprising a housing 3 ; an optional active element 6 in operative communication with a connecting means 22 , wherein the active element 6 and the connecting means 22 are disposed within the housing 3 ; wherein the active element 6 upon being activated is capable of exerting a force on the connecting means 22 ; a compression initiation element 4 located within the housing 3 , wherein the compression initiation element 4 comprises a shape memory material, and wherein the compression initiation element 4 upon activation facilitates the activation of the active element 6 ; and a spring stack 8 disposed adjacent to the compression initiation element 4 , wherein the spring stack 8 is in operative communication with the compression initiation element 4 and wherein the spring stack 8 is configured to radially expand within the housing 3.
1. A locking mechanism for positioning or locking an article comprising:
a housing;
an element in operative communication with a connecting means, wherein the active element and the connecting means are disposed within the housing; wherein the element upon being activated is capable of exerting a force on the connecting means, wherein the connecting means is in slidable communication with the housing and comprises a shaft, a first disc and a second disc, wherein the first and second discs are spaced apart and fixedly attached to the shaft;
a compression initiation element located within the housing and disposed between the first and second discs, wherein the compression initiation element comprises a shape memory material, and wherein the compression initiation element upon activation facilitates the movement of the element; and
a spring stack disposed between the first and second discs and adjacent to the compression initiation element, wherein the spring stack is in operative communication with the compression initiation element and wherein the spring stack is configured to axially expand within the housing.
2. The locking mechanism of claim 1 , wherein the shape memory material comprises a composition that has the ability to remember its original shape upon the application of an activation signal.
3. The locking mechanism of claim 2 , wherein the activation signal is a change in temperature.
4. The locking mechanism of claim 1 , wherein the stack undergoes radial expansion upon being compressed, and wherein the radial expansion of the spring stack promotes locking of an article that is in operative communication with the locking mechanism.
5. The locking mechanism of claim 1 , wherein the housing houses the element, the connecting means, the compression initiation element, and the spring stack and wherein the connecting means is in slideable communication with the housing.
6. The locking mechanism of claim 5 , wherein the element, the connecting means, and the spring stack act cooperatively with each other to permit positioning and/or locking of article that is in communication with the locking mechanism.
7. The lacking mechanism of claim 1 , wherein the compression initiation element in its original state is in circumferential contact with an inner surface of a housing that houses the compression initiation element, and wherein the compression initiation element in its original shape applies a radial load against the inner surface of the housing.
8. The locking mechanism, of claim 1 , wherein the compression initiation element comprises a split ring that comprises a circumferential slot into which is disposed a ring, wherein the ring comprises a shape memory material.
9. The locking mechanism of claim 1 , wherein the compression initiation element comprises a circular hoop element, with a cross-member manufactured from a smart material that can contract upon activation and wherein the circular hoop element upon deformation contacts the inner surface of the housing.
10. The locking mechanism of claim 1 , further comprising a second compression initiation element disposed between the first cylindrical disc and the second cylindrical disc.
11. The locking mechanism claim 1 , wherein the element comprises an expansion spring and/or a retraction spring and wherein the expansion spring and/or the retraction spring comprises a shape memory material.
12. The locking mechanism of claim 1 , wherein the locking mechanism is capable of resisting a compressive force and/or a tensile force,
13. The locking mechanism of claim 1 , wherein the locking mechanism is capable of infinite detent.
14. A method for operating a locking mechanism comprising:
activating a compression initiation element that comprises a shape memory material by the application of an external stimulus;
decompressing a spring stack, wherein the spring stack comprises one or more springs;
moving an element in a manner effective to displace a connecting means disposed between an article and a reference frame, wherein the compression initiation element, the spring stack and the connecting means at all disposed within a housing, wherein the connecting means is in slidable communication with the housing and comprises a shaft, a first disc and a second disc, wherein the first and second discs are spaced apart and fixedly attached to the shaft, and wherein the compression initiation element and the spring stack are intermediate to the first and second discs.
15. The method of claim 14 , wherein the activating of the compression initiation element reduces the radial load and the axial friction between the compression initiation element and the housing as well as between the spring stack and the housing.
16. The method of claim 14 , wherein activating the compression initiation element comprises heating the shape memory material above its transition temperature and enabling it to apply a compressive force on the compression initiation element.
17. The method of claim 14 , wherein decompressing the spring stack promotes radial contraction of the springs in the stack, and wherein the radial contraction promotes a reduction in the axial friction between the spiring stack and the housing.
18. The method of claim 14 , further comprising radially expanding the springs in the spring stack to promote locking of the article with respect to the reference frame.
19. The method of claim 14 , wherein moving the element comprises expanding an expansion spring and/or retracting a retraction spring.