Physik Instŕumente (pi) Gmbh & Co. Kg

Pi Ceramic Gmbh

Pi Ceramic Gmbh Keramische Technologien Und Bauelemente

Physik Instrumente Gmbh & Co. Kg

Physik Instrumente (pi) Se & Co. Kg

Wladimir Wischnewskiy

Alexej Wischnewski

Alexej Wischnewskij

Reinhard Hübner

Ulrich Brüggemann

Siegfried Lindig

Alexej Wischnewskiy

Oleksiy Vyshnevskyy

Alexei Wischnewskij

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 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.

The invention relates to an ultrasonic actuator () with a polarization axis P, said actuator being made of a piezoelectric ceramic. The ultrasonic actuator () has a temperature expansion coefficient which is parallel to the polarization axis P and which differs from a temperature expansion coefficient that is perpendicular to the polarization axis P, and at least one friction element () is arranged on the ultrasonic actuator. The friction element () consists of an anisotropic monocrystal with temperature expansion coefficients which are different along the three crystal axes a, b, and c. The temperature expansion coefficient along a first of the three crystal axes is the lowest, and the temperature expansion coefficient along a second of the three crystal axes is the greatest. The friction element () is aligned relative to the ultrasonic actuator () such that the first crystal axis is parallel to the polarization axis P of the ultrasonic actuator (), and the second crystal axis is perpendicular to the polarization axis P of the ultrasonic actuator (). The invention additionally relates to an ultrasonic motor with an ultrasonic actuator of the aforementioned type.

A method for electrically exciting a piezoelectric actuator of an ultrasonic motor is described. The ultrasonic motor has at least one acoustic standing wave generator, including an exciter electrode and a general electrode, wherein a capacitance Cis developed between the exciter electrode and the general electrode. The method includes: applying a rectangular exciter voltage Uto the exciter electrode and the general electrode of the acoustic standing wave generator; providing a voltage Uwith the aid of a feedback element; separating a voltage ufrom a voltage uwith the aid of a pulse filter; and changing the frequency of the rectangular exciter voltage in such a way that the phase shift between the piezoelectric current Iand the rectangular exciter voltage Uis substantially zero. A device for electrically exciting a piezoelectric actuator of an ultrasonic motor is also described.

Method and device for electrically exciting an actuator for an ultrasonic motor

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.

An ultrasonic actuator includes at least one primary waveguide resonator, with each primary generator being in flat, at least one auxiliary waveguide resonator, with each auxiliary generator being in contact in order to form an acoustic standing wave, at least one crosspiece that connects one of the at least one primary waveguide resonators and one of the at least one auxiliary waveguide resonators to each other at least in sections, and wherein at least one friction track or friction rail is arranged on the crosspiece wherein the at least one primary waveguide resonator and the at least one auxiliary waveguide resonator is an open linear waveguide, and the at least one crosspiece functions as a totalizing device of the acoustic standing waves propagated in the primary and auxiliary waveguide resonators, so that the at least one crosspiece functions as the generator of a simulated travelling wave.

Ultrasonic actuator for a linear ultrasonic motor and linear ultrasonic motor having an ultrasonic actuator

An ultrasonic motor is described. The ultrasonic motor includes a plurality of plate-shaped piezoelectric ultrasonic actuators. Each of the ultrasonic actuators includes at least one friction element allocated thereto. Each ultrasonic actuator or each of one or more pairs of ultrasonic actuators is assigned an element to be driven. The ultrasonic motor also includes a housing. The ultrasonic motor also includes an electric excitation device. The elements to be driven are movable independently of each other, and each ultrasonic actuator or each of the one or more pairs of ultrasonic actuators is arranged in a holder. The holders are pressed against each other by housing side covers. The friction elements on the ultrasonic actuators are pressed against a friction layer of the corresponding element to be driven by an elastic interlayer that is in contact with edge surfaces of the ultrasonic actuators that are arranged opposite the friction elements.

An exemplary actuator in the form of a plate is disclosed, which includes, at least two generators for exciting an acoustic standing wave in the actuator. The actuator can have at least two main surfaces and a plane of symmetry S running perpendicularly to the main surfaces, with respect to which the generators are arranged symmetrically. A first lateral surface area can have a length L that substantially corresponds to the wavelength of the acoustic standing wave excited in the actuator. A second lateral surface area of the actuator can have a length (B) that is greater than the wavelength of the acoustic standing wave excited in the actuator, and that is not equal to a multiple of half the wavelength of the excited acoustic standing wave.

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Rathenow, Germany

Wladimir Wischnewskiy