Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1992-07-14
1996-07-09
Skudy, R.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 44, 310216, 310154, 310254, 310261, H02K 100
Patent
active
055347398
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an electric machine comprising an induction part provided with conductor coils, and an exciter part, with an air gap being provided between said induction part and said exciter part, the induction part and the exciter part being movable relative to each other and the induction part having grooves provided with coils between adjacent teeth projecting in the direction towards the air gap.
BACKGROUND OF THE INVENTION
With conventional electric machines, the cross-section of the induction part teeth--as seen in a section parallel to a plane along the air gap--is at least substantially constant across the height of each tooth, i.e. progressively from the tooth tip adjacent the air gap to the tooth base. This conventional design is not optimum with respect to the magnetic flux conditions in the teeth of the induction part. For, when progressing from the tip to the base of a tooth, an increasing number of windings of the coils located in the grooves participate in the production of magnetic stray flux from tooth to tooth across the groove located therebetween, so that the magnetic flux density is considerably higher at the base or root of the tooth than at the tip of the tooth. Consequently, the tip of the tooth is magnetically not fully utilized, whereas the base of the tooth sets the limit of magnetic utilization.
It is the object of the invention to provide an electric machine of the type indicated at the outset, in which the magnetic flux density utilization of the teeth of the induction part is improved.
SUMMARY OF THE INVENTION
For meeting this object, the electric machine according to the invention is characterized by teeth of the induction part, the width of which--as measured parallel to a plane along the air gap and at right angles to the direction of relative movement of induction part and exciter part--is greater at the respective tooth base than at the respective tooth tip adjacent the air gap. Thus, according to the invention, the particular tooth presents a cross-section which increases in the direction from the tip to the base of the tooth, whereby the magnetic flux density, when one progresses in this direction, changes to a lesser extent than in the prior art. Preferably the entire tooth width increases gradually from the tip to the base of the tooth in such a manner that the magnetic flux density is substantially constant along the particular tooth.
It is pointed out that it is not cogently necessary that all induction part teeth of the machine be constructed in the manner as described hereinbefore. Depending on the constructional design of the machine, it may be sufficient that only part of the teeth is designed in this manner. Furthermore, reference is made to the case that part of the teeth is not provided with coils; especially in case of such teeth, the broadening or widening according to the invention can be dispensed with.
The electric machine according to the invention may be an electric motor or a generator for generating current. It may be a linear or a rotatory machine.
Within the class of rotatory electric machines, it may be a machine with a cylindrical air gap or a machine with a planar air gap extending at right angles to the axis of rotation (disk armature construction type).
A preferred development of the invention provides that the tooth widening portions provided in comparison with the respective tooth tip are formed at their free ends--as measured in the direction of relative movement--with smaller dimensions than at their transition ends. In this manner, the grooves widen as measured in the direction of relative movement--at those locations where the tooth widening portions are. Consequently, the magnetic stray fluxes are reduced directly from one tooth widening portion to the next tooth widening portion.
Preferably the magnetic return path portions between the teeth--as measured in the same direction as said tooth width--have substantially the same width as the adjacent teeth bases. In this manner, a substantially cons
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patent: 5352948 (1994-10-01), Kirn
Ehrhart Peter
Grundl Andreas
Heidelberg Gotz
Magnet-Motor Gesellschaft fur magnetmotorische Technik mbH
Skudy R.
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