Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2001-04-06
2002-08-27
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
Reexamination Certificate
active
06441536
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a wobble motor for linear and/or rotary movements.
Electromagnetic motors are known in which a rotary movement is converted into a linear movement by a gear worm.
The references by M. Bexell, S. Johansson, titled “Fabrication and Evaluation of a Piezoelectric Miniature Motor”, Sensors and Actuators 75 (1999) p. 8-16, and M. Bexell, S. Johansson, titled “Characteristics of a Piezoelectric Miniature Motor”, Sensors and Actuators 75 (1999) p. 118-130, disclose a miniaturized, “inchworm motor” in which a rotation is effected by contraction and bending of a plurality of piezoelectric elements.
A reference by G. Schadebrodt and B. Salomon, titled “The Piezo Traveling Wave Motor, a New Element in Actuation”, PCIM, July 1990, describes a traveling wave motor in which a stator uses the piezeoelectric effect to generate a resonant wave motion on its surface, and thus drives a rotor.
A further piezoelectrically driven traveling wave motor is described in European Patent EP 0 788 664 B1.
A reference by M. Fleischer, H. Meixner, titled Ultraschallmotoren mit piezoelektrischem Antrieb [Ultrasonic Motors With Piezoelectric Drive], Physik in unserer Zeit, 22nd annual volume 1991, No. 4, discloses an ultrasonic motor with a piezoelectric drive in the case of which rods excited piezoelectrically in the ultrasonic region drive a cylindrical rotor by asymmetric mounting.
An overview of piezoceramic drives is given in the reference by H. Anger, titled Piezoelektrische Vibroantriebe—eine Übersicht über wesentliche technische Lösungen [Piezoelectric Vibratory Drives—An Overview Of Essential Technical Solutions], Hermsdorfer technische Mitteilungen, 30th annual volume, June 1990, volume 78, pages 2481 to 2485.
Published, Non-Prosecuted German Patent Application DE 27 09 006 A1 discloses a conversion of a rotary movement into a feed movement of a shaft by a plurality of tilted rolling members, the rolling members being driven to rotate about an axis.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a Wobble motor which overcomes the above-mentioned disadvantages of the prior art devices and methods of this general type, which is of light-construction and efficient, in particular for generating a high torque in conjunction with a low rotational speed without an additional transmission.
With the foregoing and other objects in view there is provided, in accordance with the invention, a wobble motor. The wobble motor contains at least one shaft guided in a rotatably and axially displaceable fashion. At least one drive ring surrounds the shaft and is tilted with respect to a longitudinal axis of the shaft. The at least one drive ring is displaced about the shaft in a frictionally locked fashion and free from rotation.
The wobble motor has at least one shaft guided in a rotably and axially displaceable fashion. Furthermore, at least one drive ring is present which surrounds the shaft. The shaft can be guided, for example, via a bearing or without a bearing by a plurality of drive rings.
The at least one drive ring can, moreover, be tilted with respect to a longitudinal axis of the shaft. It can be displaced about the shaft in a frictionally locked fashion and at least partly free from rotation.
The displacement movement can be periodic, for example circular or elliptical. Of course, only segments of such movements can also be executed.
“Free from rotation” is taken to mean that the drive ring can be displaced or driven as a whole around the shaft, but at least a part of the drive ring is not substantially rotated about an axis fixed in the body. It is possible in this case for the non-rotating part of the drive ring, for example an outer annular shell, to be freely rotatable against another part, for example an inner annular shell. The displacement of the drive ring therefore takes place in a fashion free from rotation.
The frictional lock between the drive ring and shaft ensures that the movement of the drive ring is transmitted to the shaft. This does not exclude the possibility of freewheeling by canceling the frictional locking.
The tilting effects a relative inclination of the drive ring in the direction of the longitudinal axis of the shaft. The tilting can be expressed as a rule by a tilting angle, which can be constant or variable in time.
It may be assumed for the purpose of better understanding in the following description that the longitudinal axis of the shaft is situated on the z-axis, and that the drive ring is disc-shaped. In the case of a tilting angle d=0 (“rest position”), the drive ring may be aligned with a plane (“ring plane”) which corresponds to the (x, y)-plane. However, the wobble motor is not, of course, limited to this configuration, but can also have, for example, other tilted positions or differently formed drive rings.
The wobble motor can be driven in the operating modes of pure linear drive, pure rotary drive or a combination of these two types of operation.
A plurality of drive rings can be moved independently of one another or in a fashion coupled to one another.
The wobble motor has the advantage that it is of low wear, since only rolling friction occurs. Furthermore, only a slight noise is developed. There is also the advantage that a high drive torque can be transmitted. Again, to its advantage the wobble motor can be controlled universally, for example in stepwise or continuous fashion with respect to its direction of rotation and feed direction, its rotational speed and feed rate, and its torque and feed momentum. In addition, the rotary movement and linear feed can be implemented separately or in combination. Self locking or freewheeling can also be controlled.
Furthermore, a low structural weight results in conjunction with a compact configuration, inter alia because no transmission is required.
It is also possible to achieve a favorable high efficiency. Short run up and stopping times in the millisecond range can likewise be realized.
The drive ring of the wobble motor is tilted with respect to the shaft by at least one tilting device having at least one actuator. It is advantageous when the tilting device contains at least two linear actuators. Two drive rings can be tilted by in each case one tilting device having in each case two linear actuators, or by a common tilting device having two actuators. A comparatively simple control of the tilting movement, for example by overlapping of linear movements, is possible through the use of at least two linear actuators.
It is particularly advantageous when the preferably linear actuators of the tilting device are aligned substantially parallel to the longitudinal axis of the machine, because this results in a further simplified control of the tilting movement.
It is also advantageous for the purpose of simple control of the tilting movement when the actuators of the tilting device are fitted in an angularly symmetrical fashion and at the same distance with reference to the center of the drive ring.
Advantageous for the purpose of simple control is a tilting device having three actuators, in particular fitted in an annularly symmetrical fashion and at the same distance with reference to the center of the drive ring.
It is also favorable when the at least one drive ring can be displaced about the shaft by at least one drive device containing at least two actuators which are not collinearly aligned. It is thereby possible in a simple way to execute any desired movement in a plane. Simple movement in a plane is ensured particularly in the case of a configuration of the actuators of the respective drive device perpendicular to the longitudinal axis and at right angles to one another.
Drive devices and tilting devices can also be coupled permanently, for example mechanically, and be moved by common actuators.
It is favorable when at least one actuator, in particular all the actuators, is an electromechanical actuator. In the case of an electromechanical actuator, a change in volume, and thereby
Fischer Bernhard
Gottlieb Bernhard
Kappel Andreas
Mock Randolf
Ulivieri Enrico
Dougherty Thomas M.
Greenberg Laurence A.
Locher Ralph E.
Siemens Aktiengesellschaft
Stemer Werner H.
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