Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1995-04-20
1997-12-23
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310216, 310259, 29596, 29609, H02K 112, H02K 100, H02K 1500, H01F 304
Patent
active
057010471
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to electric motors and has been devised particularly though not solely for use in home appliances.
BACKGROUND ART
Some existing single phase AC electric motors which are utilised in home appliances, for example, refrigerator/freezers for driving fans are very inefficient electrically. Also, because these motors are necessarily small, many require the propeller or blade to have a correspondingly small moment of inertia and thus a small diameter in order that the propeller may be rotated from a standstill. This requirement is in direct contrast to the need for lower noise levels that can be achieved by large diameter fans moving air at a relatively low speed.
In existing single phase permanent magnet synchronous motors running from a fixed frequency supply, various methods of starting are used that include rotor cages and mechanical resonance. These start up arrangements are then disengaged upon the rotor nearing synchronous speed. An example of a motor which utilises mechanical resonance at start up is disclosed in U.S. Pat. No. 4,861,240 (Marioni and Cavalcante). This motor, however, has the disadvantages that it produces excessive noise and its direction of rotation upon starting is random.
In some motors, the required acceleration to synchronous speed is too great, increasing wear on the motor and moving pans and thus an efficient and reliable clutch is required. In addition, when the magnetic circuit is of the substantially "horseshoe" shape, wasteful use has previously been made of the stator material.
DISCLOSURE OF THE INVENTION
It is an object of the invention to provide an electric motor which will overcome the above disadvantages or which will at least provide the public with a useful choice.
Accordingly in one aspect the invention consists in an electric motor comprising: that a substantial part of the stator flux path is parallel to the rotor axis and said rotor is positioned to electromagnetically intersect said flux path.
In a further aspect the invention consists in an electric motor comprising: of limbs, at least one winding on at least one said limb, a rotor receiving space in each of two of said limbs, said rotor receiving spaces being arranged in longitudinal alignment with each other, a permanent magnet rotor rotatably mounted in said stator with at least one permanent magnet positioned and oriented in said at least one rotor receiving space, said stator being configured and the permanent magnets in said rotor being positioned and oriented in said rotor receiving spaces in said stator so that the rotor axis is parallel to magnetic flux in two limbs of said stator so that lines of flux normal to the rotor axis act on said permanent magnets to cause rotation thereof.
In a further aspect the invention consists in an electric motor comprising a permanent magnet rotor and an excited stator, said rotor having two axially separated pole regions and said stator being configured to provide two rotor receiving pole pairs, each pair providing a rotor receiving space within which respective rotor pole regions are disposed.
In a still further aspect the invention consists in a stator for an electric motor constructed from a single piece of magnetically permeable material, a central portion of said piece having been removed and said central portion and the remaining unitary portion of said piece being juxtaposed to form a magnetic circuit having two rotor receiving spaces.
In a still further aspect the invention consists in a method of constructing a stator for an electric motor from a single piece of magnetically permeable material comprising the steps of: ends and central sides between said ends, one of said ends of said central portion comprising part of the first side of said piece; and of said first side with a central side disposed adjacent the remaining portions of said first side with rotor receiving spaces therebetween.
In a still further aspect the invention consists in a clutch mechanism driven by an electric motor for connection of a load to a s
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patent: 4613842 (1986-09-01), Ichiyama et al.
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patent: 5153475 (1992-10-01), McSparran
patent: 5339514 (1994-08-01), Whitesel
Fisher & Paykel Limited
Stephan Steven L.
Wallace, Jr. Michael John
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