Actuator and valve assembly

Abstract

An actuator for selectively moving a part relative to another part includes a shape memory wire, which contracts upon heating, and a magnetic field. One end of the shape memory wire is fixed to a first body. The other end of the shape memory wire is coupled to a second body, which is movable relative to the first body. When heated, the shape memory wire contracts and moves the second body in a direction of travel from a first position relative to the first body toward a second position. A magnetic field generates a magnetic force on the second body, which acts on and moves the second body in the direction of travel to the second position after the shape memory wire initially contracts to thereby reduce the load on the shape memory wire when the second body is moved to the second position. The actuator may be used, for example, to move the valve stem in a valve.

Description

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of the valve and actuator of the present invention;

FIG. 2 is an enlarged cross-section view of the valve and actuator of FIG. 1;

FIG. 3 is a similar cross-section view to FIG. 2 taken along a perpendicular plane to FIG. 2;

FIG. 4 is a similar view to FIG. 2 illustrating the valve in a closed state;

FIG. 5 is a similar cross-section to FIG. 2 illustrating the valve in an open state; and

FIG. 6 is a force versus stroke diagram for the force generator of the actuator.

Claims

1. A valve comprising: a valve body having a passageway through said body, said passageway forming a first port and a second port;a valve stem located in said passageway and supported for reciprocal movement in said passageway between a first position and a second position, said passageway being open to permit fluid communication between said first port and said second port when said valve stem is moved to one of said first position and said second position thereby opening said valve, and said passageway being closed between said first and second ports when said valve stem is moved to the other said first position and said second position whereby said valve is closed; andan actuator selectively moving said valve stem from said first position to said second position for opening or closing said valve, said actuator comprising: a shape memory wire, said shape memory wire contracting when heated, one end of said shape memory wire being fixed relative to said valve body and another end of said shape memory wire being coupled relative to said valve stem wherein when heated said shape memory wire contracts and moves said valve stem in a direction of travel toward said second position; anda magnetic field, said magnetic field generating a magnetic force, said magnetic force acting on said valve stem and unloading said shape memory wire, said magnetic force moving said valve stem in said direction of travel to said second position and seating said valve stem at said second position after said shape memory wire initially contracts to thereby open or close the valve.

2. The valve according to claim 1, wherein said valve stem is movable with respect to said shape memory wire, said magnetic force decoupling said valve stem from said shape memory wire when applying said magnetic force to said valve stem.

3. The valve according to claim 1, further comprising a first magnet mounted to said body and a second magnet mounted to said valve stem, said magnets generating said magnetic force.

4. The valve according to claim 3, wherein said first magnet comprises an annular magnet or a plurality of magnets mounted to said body about said valve stem.

5. The valve according to claim 3, wherein said second magnet comprises an annular magnet or a plurality of magnets mounted to said valve stem.

6. The valve according to claim 3, said passageway further defining a third port, said third port in fluid communication with said second port when said valve stem is moved the other of said first position and said second position and sealed from said first and second ports when said valve stem is moved to said one of first position and said second position.

7. The valve according to claim 1, wherein said valve comprises a pair of said shape memory wires.

8. A valve comprising: a valve body having a passageway through said body, said passageway forming a first port and a second port;a valve stem located in said passageway and supported for reciprocal movement in said passageway between a first position and a second position, said passageway being open to permit fluid communication between said first port and said second port when said valve stem is moved to said first position thereby opening said valve, and said passageway being closed between said first port and said second port when said valve stem is moved to said second position whereby said valve assembly is closed; andan actuator selectively moving said valve stem between said first and second positions, said actuator comprising: a first shape memory wire, said first shape memory wire contracting when heated, one end of said first shape memory wire fixed at a first location relative to said body and another end of said first shape memory wire coupled to said valve stem wherein when heated said first shape memory wire contracts and moves said valve stem toward said first location in a first direction of travel;a second shape memory wire, said second shape memory wire contracting when heated, one end of said second shape memory wire fixed at a second location of said body and another end of said second shape memory wire coupled to said valve stem wherein when heated said second shape memory wire contracts and moves said valve stem toward said second location of said body in a second direction of travel opposed from said first direction of travel; anda force generator, said force generator generating a force on said valve stem, said force decoupling said valve stem from said first shape memory wire after said first shape memory wire initially contracts and moves said valve stem toward said first location wherein said force moves said valve stem to said first position and seats said valve stem at said first position, and said force decoupling said valve stem from said second shape memory wire after said second shape memory wire initially contracts and moves said valve stem toward said second location wherein said force moves said valve stem to said second position and seats said valve stem at said second position.

9. The valve according to claim 8, wherein said valve stem is movable with respect to said first shape memory wire and said second shape memory wire.

10. The valve according to claim 8, further comprising a first magnet mounted to said body and a second magnet mounted to said valve stem, said magnets comprising said force generator and generating a magnetic force.

11. The valve according to claim 10, wherein said first magnet is mounted to said body about said valve stem, said second magnet being mounted to said valve stem radially inward of said first magnet, said second magnet being offset relative to said first magnet in said first direction of travel when said valve stem is moved to said first position and being offset relative to said first magnet in said second direction of travel when said valve stem is moved to said second position, when said first shape memory wire is heated and contracts and moves said valve stem away from said second position toward said first position said second magnet moves past said first magnet in said first direction of travel and generates a magnetic repulsion force therebetween in said first direction of travel to move said valve stem to said first position and to seat said valve stem at said first position, and when said second shape memory wire is heated and contracts and moves said valve stem away from said first position toward said second position said second magnet moves past said first magnet in said second direction of travel and generates a magnetic repulsion force therebetween in said second direction of travel to move said valve stem to said second position and to seat said valve stem at said second position.

12. The valve according to claim 11, wherein said first magnet comprises an annular magnet, and said second magnet comprises an annular magnet.

13. The valve according to claim 8, wherein said first shape memory wire comprises a first pair of shape memory wires, and said second shape memory wire comprises a second pair of shape memory wires.

14. The valve according to claim 13, wherein said first pair of shape memory wires are arranged in a first plane, said second pair of shape memory wires being arranged in a second plane, and said first plane being angled with respect to said second plane.

15. The valve according to claim 14, wherein said first plane is generally orthogonal to said second plane.

16. The valve according to claim 8, wherein said valve stem includes an elastomeric body for seating against said first position or said second position in said passageway.

17. The valve according to claim 8, wherein said shape memory wires extend through said valve stem.

18. The valve according to claim 17, wherein said valve stem includes a transverse passage for each wire.

19. An actuator for selectively moving a part relative to another part, said actuator comprising: a shape memory wire, said wire contracting when heated, one end of said shape memory wire fixed to a first body, another end of said shape memory wire fixed to a second body, said second body movable relative to said first body, when heated said shape memory wire contracts and moves said second body in a direction of travel from a first position relative to said first body toward a second position; anda magnetic field, said magnetic field generating a magnetic force on said second body, said magnetic force acting on and moving said second body in said direction of travel to said second position after said shape memory wire initially contracts to thereby reduce the load on the shape memory wire when the second body is moved to said second position.

20. The actuator according to claim 19, further comprising a first magnet mounted to said first body and a second magnet mounted to said second body, said magnets generating said magnetic force.

21. The actuator according to claim 20, wherein said first magnet comprises an annular magnet or a plurality of magnets mounted to said first body about said second body.

22. The actuator according to claim 20, wherein said second magnet comprises an annular magnet or a plurality of magnets mounted to said second body.

23. The actuator according to claim 19, wherein said actuator comprises a pair of said shape memory wires.

24. The actuator according to claim 19, wherein said direction of travel comprises a first direction of travel, said first magnet being mounted to said first body about said second body, said second magnet being mounted to said second body radially inward of said first magnet, said second magnet being offset in a second direction of travel opposed to said first direction of travel when said second body is moved to said first position, wherein when said shape memory wire contracts and moves said second body away from said first position toward said second position said second magnet moves past said first magnet in said direction of travel and generates a magnetic repulsion force therebetween in said direction of travel to move said second body to said second position.

25. The actuator according to claim 23, wherein said shape memory wire comprises a first shape memory wire and said direction of travel comprises a first direction of travel, said actuator further comprising a second shape memory wire, one end of said second shape memory wire fixed to said first body and another end of said second shape memory wire fixed to said second body such that when said second shape memory wire is heated and contracts said second shape memory wire moves said second body in a second direction of travel opposite said first direction of travel.

26. The actuator according to claim 25, wherein said first shape memory wire comprises a first pair of shape memory wires arranged in a first plane, said second shape memory wire comprising a second pair of shape memory wires arranged in a second plane, and said first plane being angled with respect to said second plane.

27. The actuator according to claim 19 wherein said shape memory wires extend through said second body.

28. A method of moving a first part relative to a second part, said method comprising: providing a shape memory wire, the shape memory wire contracting upon being heated;fixing one end of the shape memory wire to a first part;coupling the other end of the shape memory wire to a second part, the second part being movable relative to the first part;generating a latching force to latch the second part in a first position;heating the wire to contract the wire to thereby apply a first pulling force in a direction of travel to the second part opposing the latching force in the direction of travel to move the second part relative to the first part from the first position toward a second position in the direction of travel;reducing the latching force after the wire initially pulls on the second part;applying a driving force to the second part in the direction of travel after the latching force reduces to zero; andmoving the second part with the driving force to the second position wherein the driving force unloads the force on the wire to thereby reduce the stress on the wire.

29. The method according to claim 28, wherein said generating a latching force includes generating a magnetic force.

30. The method according to claim 29, wherein said generating a magnetic force includes mounting a first magnet to the first part and mounting a second magnet to the second part and orienting their respective poles to generate a repulsion force between the magnets.

31. The method according to claim 28, wherein the shape memory wire comprises a first shape memory wire, said fixing one end of the shape memory wire includes fixing one end of the first shape memory wire to a first portion of the first part, further comprising: providing a second shape memory wire;fixing one end of the second shape memory wire to the first part at a second portion of the first part;coupling the other end of the shape memory wire to the second part;heating the second shape memory wire to contract the second shape memory wire to thereby move the second part relative to the first part away from the second position to the first position in a second direction of travel; andwherein said applying a driving force includes applying a driving force to move the second part to the first position after the second shape memory wire contracts wherein the driving force reduces the load on the second shape memory wire to thereby reduce the stress on the second shape memory wire.