Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1997-11-14
1999-09-21
Ramirez, Nestor
Electrical generator or motor structure
Dynamoelectric
Rotary
310309, G01C 1924, H02N 1500, H02K 1716
Patent
active
059558008
DESCRIPTION:
BRIEF SUMMARY
This invention relates to levitation systems, and in particular to miniature systems provided with novel levitation and/or drive means for use in miniature rotors, motors, motion detectors, accelerometers, optical devices, positional sensors, and other applications.
Miniature systems such as rotors, gyroscopes and motion or position detection devices having dimensions of a few tens to hundreds of .mu.m or less have been proposed for use in integrated systems. Typically such miniature systems rely upon the use of mechanical bearings for suspension of the moving parts therein, and consequently due to friction can only operate for a limited period or are very inefficient.
Alternatively, levitation of inertial masses has been achieved, typically without power, using diamagnetism, or electrostatics or indeed the Meissner effect of superconductors. Micromotors based on the use of the electroquasistatic induction principle are disclosed in Bart, S. E. et al "An analysis of electroquasistatic induction micromotors", Sensors and Actuators A, 20 (1989) 97-106, and Fuhr, G. R. et al "Analysis of the torque-frequency characteristic of dielectric induction motors", Sensors and Actuators A. 33 (1992) 237-247, and on the Meissner Effect in superconductors in Kin Y et al "A levitation-type microactuator using the Meissner effect of high-Tc Superconductors", Sensors and Actuators A. 29 (1991) 143-150. Some of the disadvantages of micromotors based on these principles of levitation include, for the electroquasistic induction principle, high excitation voltages and, for the Meissner effect in superconductors, the need for a cooling system. The disclosure of all these prior publications are incorporated herein by reference.
Furthermore, miniature rotors, for example, having dimensions of a few tens to a few hundred .mu.m or less, have been proposed for use in micro motors. Typical of such proposals are the micromotors disclosed in Wagner B. "Linear and rotational magnetic micromotors fabricated using silicon technology" Proc. IEEE Microelectromech. Syst. Workshop, 1992 pp 183-189, and Guckel H. et al "On the application of deep X-ray lithography and sacrificial layers to sensor and actuator construction" Proc. Transducers '91. 6th Int. conf. Solid-State Sensors and Actuators, 1991 which are both concerned with magnetic drives, in Fan L. S. "IC-processed electrostatic micromotors", Sensors and Actuators vol 20 pp 41-47 1989 and Meheregany M. "Operation of microfabricated harmonic and ordinary side-drive micromotors" Proc. IEEE Microelectromech. Syst. Workshop, 1990 pp 1-8 which both relate to electrostatic drives, in Udayakumar K. R. et al. "Ferroelectric thin film ultrasonic micromotor" in Proc. IEEE Microelectromech. Syst. Workshop, 1991 pp 109-113 which relates to an ultrasonic drive, and in Bart S. F. and Lang J. H. "An analysis of electroquasistatic induction micromotors", Sensors and Actuators, vol 20. pp 97-106, 1989 which describes a dielectric induction drive. In Ahn C. H., Kim Y. J., Allen M. G. "A planar Variable Reluctance Magnetic Micromotor with Fully Integrated Stator and Coils" Journal of Microelectromechanical Systems, Vol 2, No 4, pp 165-173, December 1993, planar integrated meander-type inductive components and their fabrication are described, thus making possible the manufacture of micromotors with fully integrated stator and coils. The disclosures of all these prior publications are incorporated herein by reference.
For practical applications, however, the prior art has not proved to be wholly satisfactory, because the small torques produced are usually only sufficient to overcome friction and aerodynamic drag, such that the prior art micromotors do not produce useful output.
In the fields of personal and land, sea, or air navigation, and in active suspension, braking and steering systems, there is a need to provide a miniature inertial guidance system typically incorporating gyroscope and/or an accelerometer as an essential element thereof. Typical devices for use in automotive applications are required t
REFERENCES:
Journal of Vacuum Science and Technology Part A vol. 7, No. 2, Mar. 1989, pp. 214-217, Magnetic Ultrafuge With a Microshell Rotor by Pavel E. Moroz and F. Neff Weber.
Reports on Progress in Physics, vol. 44, No. 4, Apr. 1981 (England) pp. 411-477 Electromagnetic Suspension and Levitation by B.V. Jaya want.
Sensors and Actuators, vol. 20, No. 1, Nov. 15, 1981, pp. 97-106, An Analysis of Electroquasistatic Induction Micromotors Stephen F. Bart and Jeffrey H. Lang.
Proceedings of the Workshop on Micro Electro Mechanical Systems (ME, Fort Lauderdale, Feb. 7-10, 1993 No. Workshop 6, Feb. 7, 1993, Institute of Electrical and Electronics Engineering, pp.1-6.
A Planar Variable Reluctance Magnetic Micromotor With Fully Integrated Stator and Wrapped Coils by Chong H Ahn et. al.
Barret-Yates Robert
Mellor Phillip Henry
Shearwood Christopher
Williams Connel Brett
Jones Judson H.
Ramirez Nestor
University of Sheffield
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