System, method and apparatus for reducing frictional forces and for compensating shape memory alloy-actuated valves and valve systems at high temperatures

• US 7,748,405 B2
• Filed: 09/03/2004
• Issued: 07/06/2010
• Est. Priority Date: 09/05/2003
• Status: Active Grant

• Current Assignee: Alfmeier Prã¤Zision AG Baugruppen und Systemlã¶Sungen, BOE HYDIS Technology Company Limited (SK Hynix Inc.)
• Original Assignee: Alfmeier Prã¤Zision AG Baugruppen und Systemlã¶Sungen
• Inventors: Maeder, Jean-Pierre, von Behrens, Peter Emery, Ghorbal, Ali, Surendran, Sandheep K., Szilagyi, Andrei
• Primary Examiner(s): Rivell; John
• Assistant Examiner(s): PRICE, CRAIG JAMES
• Application Number:
  US10/934,825
• Publication Number:
  US 20070277877A1
• Time in Patent Office: 2,132 Days
• Field of Search: 137596-5962, 251/11, 251/336, 605/27
• US Class Current: 137/596.17
• CPC Class Codes: F16K 31/002 actuated by temperature variation thermo-electric F16K31/025
• CPC Class Codes: G05D 23/08 with bimetallic element
• CPC Class Codes: Y10T 137/1624 Destructible or deformable element controlled
• CPC Class Codes: Y10T 137/87217 Motor

Abstract

A valve system including a number of shape memory alloy (“SMA”)-actuated valves for controlling the flow of fluids is disclosed as is a variety of types of SMA-actuated valves and methods of operation. In one embodiment, a valve system includes a housing having a substantially closed cavity as well as a second port for communicating a fluid. Further, the valve system includes a first SMA actuator configured to control the position of the first seal to vary fluid flow through the firs port, and a first temperature compensator for adjusting the position of the seal by an amount proportional to temperature. A second SMA-actuated valve, driven by either a unidirectional or a bidirectional SMA actuator, controls the position of the second seal to vary fluid flow through the second port, and a second temperature compensator for adjusting the position of the second seal by another amount proportional to temperature.

Claims

1. A three-way, three-position valve system including two shape memory alloy (“

SMA”

)-actuated valves for controlling the flow of fluids, the valve system comprising;

a housing having a substantially closed cavity for maintaining a pressurized fluid, said cavity including a first inlet port, a first outlet port connected to a user device actuatable by the pressurized fluid, and a second outlet port connected to a vent;

a first SMA-actuated valve including a first seal for closing and opening said first inlet port to selectively provide pressurized fluid to the cavity, a first SMA actuator configured to control the position of said first seal to vary fluid flow through said first inlet port, and a first temperature compensator for negating contraction forces generated by said first SMA actuator due to temperature;

a second SMA-actuated valve including a second seal for closing and opening said second outlet port to selectively vent the cavity of pressurized fluid to depressurize the user device, either a bidirectional SMA actuator or a unidirectional SMA actuator configured to control the position of said second seal to vary fluid flow through said second outlet port, and a second temperature compensator negating contraction forces generated by said second SMA actuator due to temperature;

the second outlet port being located along the cavity closer to the first outlet port than to the first inlet port thereby defining a direct pressurized fluid vent path from the user device to the vent.

2. The valve system of claim 1 wherein said first SMA-actuated valve is a wire-based SMA actuator, said wire-based SMA actuator being disposed within said cavity.

3. The valve system of claim 2 wherein said wire-based SMA actuator comprises:

a plunger having a first plunger end adapted to include said first seal, a second plunger end and a shaft;

an SMA wire having a first wire end coupled to a first anchor point, a second wire end coupled to a second anchor point, and a central wire portion engaging said plunger for imparting a linear force; and

a restoring device configured to provide a restoring force to return said first plunger end in a first direction to a first position and to restore said SMA wire to a fully extended condition,

wherein said SMA wire generates contraction forces when power is applied thereto, said contraction forces causing said central portion to apply said linear force greater than said restoring force, thereby causing displacement of said first plunger end in a second direction.

4. The valve system of claim 3 wherein said wire-based SMA actuator further comprises:

a base including said first anchor point and said second anchor point; and

a coiled spring arranged coaxially about said shaft as said restoring device, said coiled spring being a compression spring that contacts said first plunger end.

5. The valve system of claim 4 wherein said wire-based SMA actuator further comprises:

a temperature compensating SMA wire as said first temperature compensator, said temperature compensating SMA wire having a first wire end coupled to a third anchor point, a second wire end coupled to a fourth anchor point, and a second central wire portion engaging said second plunger end for imparting a compensating linear force in said first direction, said base furthering including said third anchor point and said fourth anchor point,

wherein said compensating linear force counters said contraction forces of said SMA wires above a certain temperature, thereby assisting said coiled spring in restoring said first plunger position to said first position.

6. The valve system of claim 5 wherein the transition temperature of said temperature compensating SMA wire is less than that of said SMA wire.

7. The valve system of claim 3 wherein said base is a printed circuit board (“

PCB”

) including conductive paths to either open or close a circuit to activate an end of a travel switch.

8. The valve system of claim 7 wherein said second plunger end is adapted to include a collapsible contact configured to collapse onto another contact when said first plunger end reaches said second position thereby closing a circuit to remove power from said SMA wire.

9. The valve system of claim 7 wherein said wire-based SMA actuator further comprises a switch for receiving said second plunger end when said first plunger end reaches said second position, said switch being an end of travel switch configured to remove power from said SMA wire.

10. The valve system of claim 2 wherein said wire-based SMA actuator comprises:

a plunger having a first plunger end adapted to include said first seal, a second plunger end and a shaft;

an SMA wire having a first wire end coupled to a first anchor point and a second wire end coupled to a second anchor point; and

a leaf spring including said first anchor point and said second anchor point, said leaf spring being a restoring device to provide a restoring force to return said first plunger end in a first direction to a first position and to restore said SMA wire to a fully extended condition, said leaf spring is affixed to said second plunger end at a curvature point; and

a base adapted to anchor said leaf spring,

wherein said SMA wire generates contraction forces when power is applied thereto, said contraction forces causing said leaf spring to bend, thereby causing said curvature point on said leaf spring to impart a linear force greater than said restoring force to said second plunger end, thereby causing displacement of said first plunger end in a second direction.

11. The valve system of claim 2 wherein said first temperature compensator is a driver circuit configured to adjust said contraction forces dependent on temperature by decreasing current passing through said SMA wire with increasing temperature above a certain temperature.

12. The valve system of claim 11 wherein said wire-based SMA actuator comprises:

a base;

a plunger having a first plunger end adapted to include said first seal, a second plunger end and a shaft;

a first linkage having a first anchor point, a first attachment point and a first joint;

a second linkage having a second anchor point, a second attachment point and a second joint, said first anchor point and said second anchor point being coupled to said base and said first attachment point and said second attachment point coupled to said second plunger end for imparting a linear force;

an SMA wire having a first wire end coupled to said first joint and a second wire end coupled to said second joint; and

a restoring device configured to provide a restoring force to return said first plunger end in a first direction to a first position and to restore said SMA wire to a fully extended condition,

wherein said SMA wire generates contraction forces when power is applied thereto, said contraction forces moving said first joint and said second joint closer in distance, which in turn causes said first attachment point and said second attachment point to apply said linear force greater than said restoring force, thereby causing displacement of said first plunger end in a second direction.

13. The valve system of claim 12 wherein said restoring device is a coiled spring arranged coaxially about said shaft, said coiled spring being a compression spring that contacts said first plunger end, wherein said first attachment point and second attachment point are configured to pivot about an axis, said first anchor point and said second anchor point are configured to pivot about another axis, and members of said first linkage and second linkage pivot about said first joint and said second joint, respectively.

14. The valve system of claim 12 wherein said first anchor point and said second anchor point are rigidly attached to an insulating collar, which includes a passage to permit said plunger to travel through said insulating collar, said first attachment point and second attachment point are rigidly attached to an insulating cap, which is attached to said second plunger end, and said first joint and said second joint each are torsion springs that constitute said restoring device, wherein said first and said second linkages are conductive to provide power to said SMA wire.

15. The valve system of claim 11 wherein said wire-based SMA actuator comprises:

a base having a slideable mount and a base anchor point;

a plunger having a first plunger end adapted to include said first seal, a second plunger end and a shaft;

a first linkage having a first anchor point at one end that is pivotally coupled to said slideable mount, an attachment point at another end pivotally coupled to said second plunger end for imparting a linear force, and a fulcrum point;

a second linkage having a second anchor point at one end of said second linkage that is pivotally coupled to said base anchor point, said second linkage being pivotally coupled to said fulcrum point at another end of said second linkage, said second linkage having a shorter length than said first linkage;

an SMA wire having a first wire end coupled to said first anchor point and a second wire end coupled to said second anchor point; and

a restoring device configured to provide a restoring force to return said first plunger end in a first direction to a first position and to restore said SMA wire to a fully extended condition,

wherein said SMA wire generates contraction forces when power is applied thereto, said contraction forces sliding said slideable mount toward said base anchor point, which in turn causes said attachment point to apply said linear force greater than said restoring force, thereby causing displacement of said first plunger end in a second direction.

16. The valve system of claim 1 wherein said second SMA-actuated valve further comprises a unidirectional SMA actuator, said unidirectional SMA actuator being disposed within said cavity, said unidirectional SMA actuator including at least three rigid parallel-elongate members, each having a long axis and being slideable relative to one another parallel to that long axis, each connected one to another by an SMA wire such that the stroke of the actuator is substantially equal to the sum of the stroke of the SMA wires, wherein a top plate of said unidirectional SMA actuator is rigidly affixed to an anchor point in said cavity and a bottom plate includes said second seal.

17. The valve system of claim 1 wherein said second SMA-actuated valve further comprises a bidirectional SMA actuator, said bidirectional SMA actuator being disposed within said cavity, said bidirectional SMA actuator including at least five rigid parallel elongate members, each having a long axis and being slideable relative to one another parallel to that long axis, each connected one to another by an SMA wire such, said at least five rigid parallel elongate members include a top plate rigidly linked to a bottom plate and middle plates, said middle plates including a top-middle plate and a bottom-middle plate wherein said top-middle plate is rigidly affixed to an anchor point in said cavity and said bottom-middle plate includes said second seal.

18. A three-way, three-position valve system including a number of shape memory alloy (“

SMA”

)-actuated valves for controlling the flow of fluids, the valve system comprising;

a housing defining a substantially closed cavity;

means for maintaining a pressurized fluid in said cavity, said means including a first port for admitting pressurized fluid into the cavity and a second port for transferring pressurized fluid to a user device, and a vent port for venting pressuring fluid from the user device via the cavity, the second port being closer to the vent port than to the first port;

a first SMA-actuated valve including

first sealing means for closing and opening said first port,

first SMA actuation means for controlling the position of said first seal to vary fluid flow into the cavity through said first port, and

first temperature compensation means for negating contraction forces generated by said first SMA actuator due to temperature; and

a second SMA-actuated valve including

second sealing means for closing and opening said second port,

bidirectional SMA actuation means for controlling the position of said second seal to vary fluid flow from the user device through said second port and into the vent, and

second temperature compensation means for negating contraction forces generated by said second SMA actuator due to temperature.