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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
First Claim
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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.

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