Rockwell International Corporation

Rockwell Technologies, Inc.

The Boeing Company

Rockwell Science Center, Inc.

Meritor Light Vehicle Systems, Inc.

Ratnakar R Neurgaonkar

Jeffrey G Nelson

John R Oliver

Mohsen Khoshnevisan

Manouchehr E Motamedi

Carlo Bertolini

Alex P Moffatt

A self contained device for harvesting electrical energy from linear and rotary motion has a sensor with amplifiers for tensile stretching of a piezoelectric body with magnification of the applied force. The piezoelectric body is a monolithic plate with surface electrodes covering its top and bottom surfaces.

Piezoelectric energy harvester and method

A piezoelectric translator has a flat ribbon geometry and a large translation length perpendicular to the surface of the bridge. The translator includes a platform supporting the optic or micro-optic element and a slender piezo actuation system for displacing the platform. A position sensing system provides feedback to the actuation system regarding displacement of the platform. The actuation system includes a plurality of bridge actuators wherein each actuator includes a flat piezoelectric ribbon and leaf spring cap bonded to the ribbon, in single- or double-sided geometry. A stacked bridge geometry is also provided and allows increased displacement for a given applied voltage. Two collinearly placed single span bridge actuators or two-span bridge actuators can be used to provide linear translations with micro-rotation control.

Miniature piezoelectric translators for optical applications

PLZT piezoelectric ceramics having the general formula (Pb,La,)(Zr,Ti,),M,O,are fabricated in a hot forging process using PbO, TiO,, ZrO,, and La,O,powders with Nb,O,and Ta,O,added to provide 2.0-3.0% Nb,(mole %) and 2.0-3.0% Ta,(mole %) as a dopant. ZrO,and TiO,powders are mixed at a molar ratio of y/(1&minus;y), the preferred molar ratio being 55/45, calcined at approximately 1300&deg; C.-1500&deg; C., ball milled in acetone, and evaporated to a dry powder. The mixture of ZrO,and TiO,is then combined with PbO,, La,O,, Nb,O,and Ta,O,powders, and the new mixture is ball milled in acetone, evaporated to a dry powder, calcined at approximately 700&deg;-850&deg; C., and sifted to obtain a particle size of approximately 0.5-1.5 &mgr;m. The final Nb/Ta-doped PLZT powder is formed into the desired shape by cold pressing followed by sintering at approximately 1000&deg; C.-1150&deg; C. in oxygen. The PLZT ceramic material is further densified to about 98.5% of the material's theoretical maximum density by heating to approximately 1175&deg; C.-1275&deg; C. at 300-1200 psi uniaxial pressure. The resulting high temperature, high performance Nb/Ta-doped PLZT piezoelectric ceramic exhibits an average grain size of about 3 &mgr;m, a well-defined polarization hysteresis loop, reduced strain hysteresis with the application of a unipolar electric field, a breakdown strength greater than 25 kV/cm, a linear piezoelectric coefficient (d,) of about 790 pC/N, maximum strain greater than 0.16%, and a fatigue life of at least 10,cycles and a Tc of about 205-208&deg; C.

High temperature, high strain piezoelectric compositions

A high force linear displacement piezoelectric motor operates with equal force and reliability in both the push and pull mode. The new motor includes a split motor shaft having with two shaft segments that are coaxially affixed to opposite sides of an expandable and contractable displacement actuator. The displacement actuator has a piezoelectric body coincident with the axis of the shaft segments such that the expansion of the piezoelectric body increases the length of the split motor shaft. The motor has a set of clamps that receive and close on the shaft segments to hold them in place, or open to allow axial displacement of the shaft segments. Linear motion of the split shaft motor is produced by coordinating the opening and closing the clamps with the expansion and contraction of the piezoelectric body.

Push-pull high force piezoelectric linear motor

A piezoelectric moving linear motor consists of three piezoelectric actuators which are controlled relative to each other. One piezoelectric actuators causes two blocks to move away from each other in opposition to a spring force. The other two piezoelectric actuators selectively clamp a block to a guide shaft. By cyclically controlling the actuation of the three piezoelectric actuators, the motor is able to move the blocks axially along the guide shaft. Preferably, a vehicle component such as a window is fixed to one block and is caused to move along the guide shaft.

Moving linear piezoelectric motor for vehicle applications

PLZT piezoelectric ceramics having the general formula (Pb.sub.1-x La.sub.x)(Zr.sub.y Ti.sub.1-y).sub.1-(x/4) O.sub.3 are fabricated in a hot forging process using PbO, TiO.sub.2, ZrO.sub.2, and La.sub.2 O.sub.3 powders as starting materials with Nb.sub.2 O.sub.5 added to provide Nb as a dopant. The ZrO.sub.2 and TiO.sub.2 powders are mixed at a molar ratio of y/(1-y), calcined at approximately 1300.degree.-1500.degree. C., ball milled in acetone, and evaporated to a dry powder. The mixture of ZrO.sub.2 and TiO.sub.2 is then combined with the PbO, La.sub.2 O.sub.3, and Nb.sub.2 O.sub.5 powders, and the new mixture is ball milled in acetone, evaporated to a dry powder, calcined at approximately 700.degree.-850.degree. C., and sifted to obtain a particle size of approximately 0.3-2.0 .mu.m. The final PLZT powder is formed into the desired shape by cold pressing followed by sintering at approximately 1000.degree.-1150.degree. C. in oxygen. The PLZT ceramic material is further densified to about 98.5% of the material's theoretical maximum density by heating to approximately 1175.degree.-1275.degree. C. at 800-1200 psi uniaxial pressure. The resulting high performance Nb-doped PLZT piezoelectric ceramic exhibits an average grain size of about 3 .mu.m, a well-defined polarization hysteresis loop, reduced strain hysteresis with the application of a unipolar electric field, a breakdown strength greater than 25 kV/cm, a linear piezoelectric coefficient (d.sub.33) greater than 750, maximum strain greater than 0.15%, and a fatigue life of at least 10.sup.10 cycles.

Method of fabricating PLZT piezoelectric ceramics

PLZT piezoelectric ceramics having the general formula (Pb.sub.1-x La.sub.x)(Zr.sub.y Ti.sub.1-y).sub.1-(x/4) O.sub.3 are fabricated in a hot forging process using PbO, TiO.sub.2, ZrO.sub.2, and La.sub.2 O.sub.3 powders as starting materials with Nb.sub.2 O.sub.5 added to provide niobium (Nb) as a dopant. The ZrO.sub.2 and TiO.sub.2 powders are mixed at a molar ratio of y/(1-y), calcined at approximately 1300.degree.-1500.degree. C., ball milled in acetone, and evaporated to a dry powder. The mixture of ZrO.sub.2 and TiO.sub.2 is then combined with the PbO, La.sub.2 O.sub.3, and Nb.sub.2 O.sub.5 powders, and the new mixture is ball milled in acetone, evaporated to a dry powder, calcined at approximately 700.degree.-850.degree. C., and sifted to obtain a particle size of approximately 0.3-2.0 .mu.m. The final PLZT powder is formed into the desired shape by cold pressing followed by sintering at approximately 1000.degree.-1150.degree. C. in oxygen. The PLZT ceramic material is further densifted to about 98.5% of the material's theoretical maximum density by heating to approximately 1175.degree.-1275.degree. C. at 800-1200 psi uniaxial pressure. The resulting high performance Nb-doped PLZT piezoelectric ceramic exhibits an average grain size of about 3 .mu.m, a well-defined polarization hysteresis loop, reduced strain hysteresis with the application of a unipolar electric field, a breakdown strength greater than 25 kV/cm, a linear piezoelectric coefficient (d.sub.33) greater than 750, maximum strain greater than 0.15%, and a fatigue life of at least 10.sup.10 cycles.

Nb-doped PLZT piezoelectric ceramics

A method to fabricate a tuning fork resonator gyro which uses non-piezoelectric substrate structure is proposed. The tuning fork structure can be effectively rendered piezoelectric for activation and sensing by thin film deposition of a piezoelectric material. Electrical excitation of the piezo film excites vibrations in the structure of the drive tuning fork, and the gyro signal generated due to rotation can be picked up from the piezo film on the signal tuning fork. Most piezoelectric films have a much higher piezoelectric coupling than crystalline quartz, the material used in the prior art. The piezoelectric films on mechanically hard non-piezoelectric substrates are simpler for fabrication, electroding, and have a number of other advantages over the prior art. Fabrication of the tuning fork structures can be done more simply than the prior art, and deposition of the piezo films can be accomplished by sol-gel, or other thin film techniques. The proposed methods thus provide considerable flexibility to separately optimize the resonator structure in terms of the physical and mechanical properties of the structure, the required piezoelectric properties, and methods for fabrication, processing and low cost manufacturing of resonator gyros.

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Thousand Oaks, CA, United States of America

Ratnakar R Neurgaonkar