Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1990-06-05
1991-09-10
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310152, 310114, H02K 1600, H02K 2112, H02K 2126
Patent
active
050476807
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a rotating electrical machine having two mutually coaxial parts which are rotatable in relation to one another and each of which has a respective ferromagnetic core and a substantially cylindrical air gap which separates the cores of respective parts. The object of the invention is to provide such a machine, and then particularly a motor, which develops a high torque in relation to its volume and weight.
Modern electric motors which develop high torques in relation to their weight and volume are normally fitted with field poles in the form of permanent magnets.
It is known that high quality permanent magnets can be placed in the air gaps of electrical machines, without the risk of residual demagnetization. A parallelepipedic permanent magnet pole comprised of a material whose permeability is close to that of air and which is magnetized homogenously at right angles to its pole faces will act upon its surroundings in essentially the same manner as if it were replaced with a current conducting ribbon which extends along the edge surfaces of the pole and conducts an electric current whose strength is equal to the product of the coercive field strength of the material of the permanent magnet and the edge height of the pole thereof. This fictitious current conductor which leads the aforesaid fictitious current around the peripheral edge of the pole is referred to in the following as the edge conductor. Considered in this way, the force exerted on a permanent magnet pole under the influence of an externally applied magnetic field is understood to be the force exerted on the edge conductor under the influence of the external field. The edge conductors which bound the space between the two adjacent permanent magnet poles having mutually opposite polarities will therewith conduct edge currents in the same direction. An external magnetic field which penetrates through such an interspace will give rise to coacting forces of mutually equal value in those parts of the two edge conductors which lie adjacent this interspace. The manner in which the magnetic field varies within the periphery of respective pole faces has no effect on the force development.
A row of mutually adjacent permanent-magnet poles with alternately mutually opposite polarities gives rise to the largest combined driving force for a given absolute value of the external field which penetrates through the magnet pole interspaces, when the external field is directed perpendicularly to the pole faces and changes polarity from pole interspace to pole interspace. In other words, such a row of permanent magnet poles will be driven by the magnetic field which prevails at the edge lines of the pole interspaces, i.e. at the pole edges located adjacent the pole interspaces. One surprising result of this particular consideration is that for a given total size, volume and weight, of the permanent magnet and an external field of given size, the resultant force will be proportional to the number of pole interspaces and therewith the number of poles, and consequently this force, in principle, can be increased beyond all limits, by increasing the number of pole interspaces, i.e. the number of poles, without changing the combined total weight and volume of the permanent-magnet poles.
Naturally, the same reasoning can be applied when the aforesaid ficititious edge conductors are replaced with factual superconductive conductors in which large currents are able to flow with substantially no loss. Thus, in principle, permanent magnet poles can be replaced with superconductive conductors which extend around the circumference of the pole faces and conduct a direct current which corresponds to the product of the coercive field strength of the permanent magnet material and the edge height of the permanent magnet poles.
However, in the case of present day conventional electric motors equipped with permanent magnets, it is only possible to utilize to a limited extent the aforesaid circumstance that the resultant force at a given total volume and w
REFERENCES:
patent: 690060 (1901-12-01), Jacoby
patent: 2796571 (1957-06-01), Dunn
patent: 3411059 (1968-11-01), Toshimasa Kziwa
patent: 3950663 (1976-04-01), Mead
patent: 4126798 (1978-11-01), Carr, Jr. et al.
patent: 4127802 (1978-11-01), Johnson
patent: 4206374 (1980-06-01), Goddijn
patent: 4661736 (1987-04-01), Kawada et al.
patent: 4810914 (1989-03-01), Karidis et al.
patent: 4882515 (1989-11-01), Radomski
patent: 4920294 (1990-04-01), Christiaens et al.
Astra-Tech AB
Haszko Dennis R.
Stephan Steven L.
LandOfFree
Rotating electrical machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rotating electrical machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotating electrical machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-542341