Physik Instŕumente (pi) Gmbh & Co. Kg

Physik Instrumente (pi) Se & Co. Kg

Physik Instrumente Gmbh & Co. Kg

Alexej Wischnewski

Wladimir Wischnewskiy

Dieter Wienecke

Kurt Sinske

Christoph Stiebel

Method for operating an ultrasonic motor with an ultrasonic actuator formed as a plate and an electrical excitation device. The ultrasonic actuator has at least four identical volume regions arranged symmetrically in relation to a transverse plane and in relation to a longitudinal plane, each volume region forming acoustic standing waves and static bending deformations. The electrical excitation device provides at least one electric alternating voltage and two static electric voltages the at least one alternating voltage Ubeing applied in a dynamic operating mode simultaneously to two of the generators for forming an acoustic standing wave in the ultrasonic actuator, and the two static electric voltages being applied in a static operating mode simultaneously to all generators for forming a static bending deformation of the ultrasonic actuator.

Method for operating an ultrasonic motor

An ultrasonic motor and method are disclosed with an element to be driven and a plate-shaped ultrasonic actuator made of polarized electromechanical material with at least two friction elements arranged on one of its side. The ultrasonic actuator can include at least two generators for acoustic standing waves and each of the generators can include two cooperating and spaced sub-generators, and one respective sub-generator of a generator is located between the sub-generators of an adjacent generator, and the sub-generators of one generator are arranged in mirror image to the sub-generators of an adjacent generator. A polarization direction of the electromechanical material of one of the two sub-generators of one generator differs from the polarization direction of the electromechanical material of the other sub-generator of the same generator.

Ultrasonic motor having generators formed of cooperating and spaced apart first and second sub-generators

An ultrasonic motor, is disclosed having an ultrasonic actuator in the form of a rectangular piezo-electric plate, which has two generators for acoustic standing waves and on which at least two friction elements are arranged, an element to be driven, and an electric excitation device. The piezoelectric plate of the actuator is divided into two pairs of diagonally oppositely disposed sections by two virtual planes which extend perpendicularly to each other and which extend through the center line of the main surfaces of the actuator, wherein each of the generators includes two parts which can be operated in an antiphase manner and each of which is arranged in a diagonal section of the piezoelectric plate, and the friction elements are arranged on one or two end faces of the piezoelectric plate.

Ultrasonic motor having a diagonally excitable actuator plate

An ultrasonic motor includes an actuator with a piezo-electric plate, at least one friction element, an element to be driven in active contact with the friction element, a tensioning device for pressing the friction element against the element to be driven, and a thermo-compensation platform having abutting sections by which displacement of the actuator is only possible along abutting side surfaces of the piezo-electric plate. The tensioning device includes two rotation angle levers of which two tension lever arms are connected to one another via a tensioned tension spring, to exert torque on the rotation angle lever such that pressure lever arms will act on the actuator to be linearly guided by the abutting sections in the direction of the element to be driven.

Ultrasonic motor with thermal compensation platform

The invention relates to a method for joining a ceramic friction element () to a piezoelectric element (), comprising, among other things, the following steps: pressing () a joining surface () of the friction element and a contact surface () of the piezoelectric element against each other with a low-melting glass mass () arranged therebetween and maintaining the pressing force for all subsequent steps; heating () the piezoelectric element and the friction element to a defined temperature above the Curie point of the piezoceramic material of the piezoelectric element and above the melting point of the low-melting glass mass; thereafter, while maintaining the temperature, applying an electric polarization voltage Up to electrodes of the piezoelectric element; removing the polarization voltage after the Curie point has been fallen below; and cooling the piezoelectric element and the friction element to room temperature without an electric voltage being applied to the electrodes.

Method for joining a ceramic friction element to a piezoceramic element

An exemplary ultrasonic motor includes an ultrasonic actuator, functioning as a waveguide resonator, formed as a rectangular piezo-electrical plate having two main surfaces and side surfaces that join the main surfaces together, an element to be driven and an electrical excitation device. At least one friction element is arranged on at least one side surface of the ultrasonic actuator and is in frictional contact with the element to be driven. The piezo-electrical plate is divided into three parts. The central part forms a generator for an acoustic longitudinal standing wave, and the peripheral parts bordering the central part form generators for an acoustic bending standing wave. Each generator is electrically connected to the electrical excitation device-can be electrically controlled, and can be divided into two equally-sized and electrically individually controllable sub-generators. Each sub-generator has layers of excitation electrodes, layers of general electrodes, and layers of piezo-ceramics arranged therebetween.

Ultrasonic motor

An ultrasonic actuator made of polarized piezoelectric material in the form of a single-layer or multilayer flat rectangular plate with two main faces, at least four lateral faces joining the main faces, and a thickness T, which is defined by the distance between the main faces in the direction of their surface normals, and wherein on both the one main face and the other opposite main face at least one layer including two triangular electrodes imposingly arranged and separated by a diagonal separating region, the electrodes on the one main face being offset relative to the electrodes on the other main face by 90&#xb0;. The ultrasonic actuator is characterized in that on at least one of the lateral faces there are two mutually spaced friction elements designed to contact at least one element that is to be driven by the ultrasonic actuator.

Ultrasonic actuator

A method and device are disclosed for actuating a piezoelectric motor by two driving electrodes by applying periodic control voltages to the driving electrodes. A simplified closed-loop control of the piezoelectric motor is realized by reducing the static friction of a friction contact between a friction element of the piezo-electric motor and an output element to be driven by the friction element without a propulsion of the output element at the same time. In exemplary embodiments, the periodic control voltages are applied with a phase shift to the driving electrodes in a first step of the method, and in a second step of the method, the amplitude ratio of the periodic control voltages is changed with respect to the first step.

Method and device for controlling a piezoelectric motor

A method for controlling an ultrasonic motor. From a starting velocity or starting position of the driven element, the method includes adjusting the frequency of the electrical excitation voltage such that it is equal to or close to the mechanical resonance frequency of the ultrasonic actuator; changing the frequency of the electrical excitation voltage using the signal of the velocity sensor or the position sensor towards the anti-resonance frequency of the ultrasonic actuator until an end velocity or an end position of the driven element is reached; and controlling the end velocity or position of the driven element with a predetermined accuracy by means of antiphase frequency change. Also disclosed is a corresponding control arrangement for an ultrasonic motor having an ultrasonic actuator with at least two acoustic wave generators, a driven element and a generator via a frequency adjustment.

Method for controlling an ultrasound motor and corresponding control arrangement

The invention relates to an ultrasonic motor, comprising a piezoelectric ultrasonic actuator () having four friction elements () disposed thereon, a friction surface () which is in frictional contact with the friction elements, and an electrical excitation device (), wherein the ultrasonic actuator is in the shape of a ring or hollow cylinder, having an inner circumferential surface (), an outer circumferential surface () and two planar end surfaces () connecting the inner and the outer circumferential surfaces. The four friction elements are disposed on one of the end surfaces of the ultrasonic actuator so as to be spaced equidistantly with respect to the circumferential direction, such that in each case two of the friction elements lie diametrically opposite, and the ultrasonic actuator comprises twelve identical circumferential sections (), each of which has a generator for an acoustic standing wave to be formed in the ultrasonic actuator and the deformations of the ultrasonic actuator caused by the standing wave lead to deflections of the friction elements on a movement path inclined with respect to the end surface and/or a movement path substantially perpendicular to the end surface. Each generator has at least one excitation electrode (), at least one general electrode () or a section of a general electrode and a layer of piezoceramic () disposed between the excitation electrode and the general electrode or the section of the general electrode.

An ultrasonic motor having an ultrasound actuator in the form of a piezoelectric hollow cylinder with friction elements on at least one of its end surfaces, and having a rotor in effective contact with the friction elements and an electric excitation device. The actuator is subdivided in the circumferential direction in an even number of sectors Sa and Sb with the sectors Sa and Sb alternating and being adjacent in circumferential direction, and the friction elements being arranged in the range of adjacency of neighboring sectors. Each of the sectors Sa and Sb is formed by exciter electrodes and general electrodes alternatingly arranged in the axial direction of the hollow cylinder, wherein a layer of piezoelectric material is arranged between neighboring excitation electrodes and general electrodes.

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Wörth, Germany

Alexej Wischnewski