Forced vibration piezo generator and piezo actuator

Abstract

Piezoelectric elements for power generation and/or actuation are described. An aspect is directed to generators utilizing piezoelectric elements for electrical power generation. Such a generator can use one or more arrays of piezoelectric cantilevers for electrical power generation in conjunction with modulated air pressure used for exciting the cantilevers. The pressure level/modulation and cantilever area can be controlled variables for maximizing the bending, and hence energy generation, of the cantilevers. A further aspect is directed to hydraulic fluid actuators utilizing a pumping mechanism that includes a piezoelectric element. The linear actuators can advantageously utilize the high force and high frequency characteristics of a piezoelectric membrane in conjunction with a large stroke and actuation direction conversion afforded by hydraulic transmission.

1 . An actuator comprising:
 a housing including a fluid reservoir;   a piezoelectric actuator adjacent the fluid reservoir, wherein the piezoelectric actuator includes a piezoelectric element configured to deform in response to an applied electric field to displace fluid in the fluid reservoir; and   a movable surface hydraulically coupled to the fluid reservoir and configured for movement in response to displacement of the fluid in the fluid reservoir.   
     
     
         2 . The actuator of  claim 1 , wherein the piezoelectric actuator comprises at least one material selected from the group consisting of zinc oxide, barium titanite, lead zirconate titanate, lead lanthanum zirconate titanate, lead magnesium niobate, potassium niobate, potassium sodium niobate, potassium tantalite niobate, and piezoelectric polymers. 
     
     
         3 . The actuator of  claim 1 , wherein the fluid reservoir contains a hydraulic fluid. 
     
     
         4 . The actuator of  claim 1 , wherein the movable surface is coupled to the housing by a bellows. 
     
     
         5 . The actuator of  claim 1 , wherein the movable surface is coupled to the housing by a flexure. 
     
     
         6 . The actuator of  claim 1 , wherein the movable surface comprises a piston. 
     
     
         7 . The actuator of  claim 1 , wherein the movable surface is separated from the housing by a seal configured to constrain the fluid in the fluid reservoir. 
     
     
         8 . The actuator of  claim 1 , wherein the housing and the movable surface are microelectromechanical systems. 
     
     
         9 . A system comprising:
 a plurality of pump chambers, wherein each of the plurality of pump chambers includes a housing comprising a fluid reservoir, and a pump rib hydraulically coupled to the fluid reservoir; and   a piezoelectric actuator hydraulically coupled to the fluid reservoir;   wherein the pump rib is configured to pump a fluid.   
     
     
         10 . The system of  claim 9 , wherein the piezoelectric actuator comprises at least one material selected from the group consisting of zinc oxide, barium titanite, lead zirconate titanate, lead lanthanum zirconate titanate, lead magnesium niobate, potassium niobate, potassium sodium niobate, potassium tantalite niobate, and piezoelectric polymers. 
     
     
         11 . The system of  claim 9 , wherein the fluid reservoir contains a hydraulic fluid. 
     
     
         12 . The system of  claim 9 , wherein each pump rib is coupled to the housing of the respective pump chamber by a flexure. 
     
     
         13 . The system of  claim 9 , wherein each pump rib comprises a piston. 
     
     
         14 . A method comprising:
 applying a voltage across a piezoelectric element of a piezoelectric actuator, wherein the applied voltage causes the piezoelectric element to deform such that a fluid in a fluid reservoir is displaced;   wherein displacement of the fluid causes movement of a movable surface hydraulically coupled to the piezoelectric element.   
     
     
         15 . The method of  claim 14 , further comprising modifying the voltage applied across the piezoelectric element to control movement of the movable surface. 
     
     
         16 . The method of  claim 14 , wherein the piezoelectric actuator comprises at least one material selected from the group consisting of zinc oxide, barium titanite, lead zirconate titanate, lead lanthanum zirconate titanate, lead magnesium niobate, potassium niobate, potassium sodium niobate, potassium tantalite niobate, and piezoelectric polymers. 
     
     
         17 . The method of  claim 14 , wherein the movable surface is connected to the housing by a bellows, the method further comprising passing fluid toward the movable surface through the bellows. 
     
     
         18 . The method of  claim 14 , wherein the movable surface is connected to the housing by a flexure. 
     
     
         19 . The method of  claim 14 , wherein the movable surface comprises a piston. 
     
     
         20 . The method of  claim 14 , wherein the movable surface is separated from the housing by a seal configured to constrain a fluid in the fluid reservoir. 
     
     
         21 . A method comprising:
 applying a voltage across a piezoelectric element of a piezoelectric actuator, wherein the applied voltage causes deformation of the piezoelectric element such that a fluid in a fluid reservoir of a pump chamber is displaced;   wherein the displacement of the fluid causes a change in pressure in the pump chamber and movement of a pump rib associated with the pump chamber.   
     
     
         22 . The method of  claim 21 , further comprising pumping a second fluid in accordance with movement of the pump chamber. 
     
     
         23 . The method of  claim 21 , wherein the piezoelectric actuator comprises at least one material selected from the group consisting of zinc oxide, barium titanite, lead zirconate titanate, lead lanthanum zirconate titanate, lead magnesium niobate, potassium niobate, potassium sodium niobate, potassium tantalite niobate, and piezoelectric polymers. 
     
     
         24 . The method of  claim 21 , wherein the fluid reservoir contains a hydraulic fluid. 
     
     
         25 . The method of  claim 21 , wherein each pump rib is connected to the housing of the respective pump chamber by a flexure. 
     
     
         26 . The method of  claim 21 , wherein each pump rib comprises a piston.