Micromembrane actuator
AssigneeThe Regents of the University of California
InventorsGregory Carman, Daniel Shin
Life of this patent
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Abstract
Thin film shape memory alloy (SMA) micro pump that has high work density and high frequency response. A miniature SMA pump is used to rectify liquid to achieve stroke. Controlled fluid flow provides forced convection cooling on the SMA membrane that allows the micro pump to operate at high operational frequencies and high work density.
Claims33
An actuator mechanism comprising:
- an actuator body comprising an actuation chamber having a membrane seat surface;
- a membrane comprising a shape memory alloy that has a martensite-austenite transition temperature, said membrane being located over said membrane seat surface to define a pump chamber between said membrane seat surface and said membrane, said membrane being movable from an undistorted form to a distorted form;
- at least one inlet through which fluid is introduced into said pump chamber;
- at least one outlet through which fluid is removed from said pump chamber, said outlet being located at a spaced location from said inlet;
- a bias pressure applicator that introduces said fluid into said pump chamber at a temperature that is below said martensite-austenite transition temperature;
- and
- a heating system that heats said membrane to an actuation temperature that is above said martensite-austenite transition temperature when said membrane is in said distorted form.
An actuator mechanism according to claim 30 wherein said inlet flow control mechanism comprises an inlet pressure check valve that prevents flow of fluid from said pump chamber out through said inlet when said fluid in said pump chamber is under a pumping force exerted by said membrane.
An actuator mechanism according to claim 31 wherein said outlet flow control mechanism comprises an outlet pressure check valve that prevents flow of fluid from said outlet back into said pump chamber wherein said fluid in said pump chamber is under a bias force exerted by said bias pressure applicator.
A method for pumping fluid comprising the steps of:
- A) providing an actuator mechanism comprising:
- an actuator body comprising an actuation chamber having a membrane seat surface;
- a membrane comprising a shape memory alloy that has a martensite-austenite transition temperature, said membrane being located over said membrane seat surface to define a pump chamber between said membrane seat surface and said membrane, said membrane being movable from an undistorted form to a distorted form;
- at least one inlet through which the fluid to be pumped is introduced into said pump chamber;
- at least one outlet through which said fluid is removed from said pump chamber, said outlet being located at a spaced location from said inlet;
- B) introducing said fluid into said pump chamber at a temperature that is below said martensite-austenite transition temperature and at a bias force, and
- C) heating said distorted membrane to an actuation temperature that is above said martensite-austenite transition temperature to exert a pumping force against the fluid in said fluid chamber.
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In a method for pumping a fluid wherein a membrane comprising a shape memory alloy is repeatedly heated and cooled, the improvement comprising forced convective cooling of said membrane by introducing a pressurized flow of said fluid into contact with said membrane at an inlet location and flowing said liquid over said membrane to an outlet location that is spaced from said inlet location.
Dependencies are inferred from the claim text.