Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-02-28
2002-05-07
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S156180, C310S156220, C310S156650
Reexamination Certificate
active
06384504
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an electric machine comprising a stator and a rotor separated by an air gap, with
(a) the rotor being composed with permanent magnets magnetized substantially in a circumferential direction, and with one magnetic flux conducting piece assembly including at least one magnetic flux conducting piece between two adjacent permanent magnets;
(b) the permanent magnets—when looking at the overall geometry—each having an increasing circumferential width from the head portion on the side of the air gap to the foot portion;
(c) and the conducting piece assemblies between two adjacent permanent magnets—when looking at the overall geometry—each having a decreasing circumferential width from the head portion on the side of the air gap to the foot portion.
The electric machine may be, in particular, an electric motor or a current generator. The invention relates, in particular, to electric machines in which the air gap has a substantially cylindrical configuration.
In the electric machines of the type indicated at the outset, a considerable magnetic force acts on each of the magnetic flux conducting pieces in the direction towards the air gap. When the machine is formed with an internal rotor, the centrifugal force acting on the magnetic flux conducting piece assembly is superimposed on the force of attraction during operation of the machine so as to increase the same. When the machine is formed with an external rotor, the centrifugal force now acting on the magnetic flux conducting piece assemblies in the opposite direction is superimposed on the magnetic force of attraction during operation of the machine. The overall geometry of the conducting piece assemblies with decreasing circumferential width from the head portion on the side of the air gap to the foot portion further aggravates safe locating of the conducting piece assemblies in the rotor.
SUMMARY OF THE INVENTION
The problem to be solved by the invention is to make available electric machines of the type indicated at the outset, in which the conducting piece assemblies are held on the rotor in a constructionally simple, but nevertheless extremely reliable manner.
According to a first solution of this problem, the machine according to the invention is characterized in
(d) that the conducting pieces at the foot end each have a widened portion in circumferential direction, having at least one shoulder through which they are supported on an adjacent permanent magnet against displacement in the direction towards the air gap.
Due to the provision of the widened portion at the foot end of the particular conducting piece, the widened portion indeed is not located in an optimum region under the aspect of mechanical strength, said region being narrower in circumferential direction than at a location further towards the head end. On the other hand, the widened portion is situated in a region where the relatively lowest impairment results for the configuration that is advantageous in terms of magnetic flux passage.
It is pointed out that the at least one shoulder need not necessarily extend substantially in tangential direction of the rotor (although this constitutes a preferred embodiment), but may also extend obliquely with respect to the tangential direction, but parallel to the rotor axis.
According to a second solution of the above-indicated problem according to the invention the machine is characterized in
(d) that the conducting pieces each have at least one shoulder through which they are supported on a supporting member against displacement in the direction towards the air gap, the supporting member being constituted by the rotor or attached to the rotor.
In this solution according to the invention, the at least one shoulder thus is no longer provided necessarily at the foot end of the respective conducting piece, but may be provided at any location of the radial extension of the conducting piece.
With numerous embodiments of the invention, the respective conducting piece assembly comprises only one conducting piece between two adjacent permanent magnets. Especially in this case, it is, as a rule, practical and favorable to provide the respective conducting piece on both sides with a shoulder, though it is alternatively possible, as well, to utilize a shoulder on only one side of the conducting piece.
According to another, preferred development of the invention the conducting piece assemblies consist of two conducting pieces each, having a shoulder on one side or on both sides. Conducting piece assemblies with more than two conducting pieces are possible as well.
Preferably, two conducting pieces each of adjacent conducting piece assemblies can be connected to each other via the permanent magnet disposed therebetween. This results in a U-shaped conducting piece configuration enclosing the interposed permanent magnet and thus being supported on the latter.
It is preferred, furthermore, that a pocket be formed between the two conducting pieces of the respective conducting piece assembly, in which a supporting member is disposed. With this configuration, a portion of the conducting pieces that is not adjacent the permanent magnets thus is employed for fixing them to the rotor. According to a further development it is advantageous to connect two supporting members of two adjacent conducting piece assemblies so as to form a common supporting frame. This renders the construction somewhat more complex indeed, but provides the possibility of a particularly stable fixation of the supporting members on the rotor.
The expression “at least one shoulder” as used repeatedly hereinbefore covers on the one hand the possibilities that a shoulder is provided only on one circumferential end or that a shoulder is provided on both circumferential ends. On the other hand, this also covers the possibilities that two or even more shoulders are provided radially behind each other at the corresponding location (e.g. a so-called fir-tree foot), or only one shoulder without radially spaced neighbouring shoulder (which is the most frequent design).
According to a third solution of the problem mentioned, the machine according to the invention is characterized in
(d) that the conducting piece assemblies each include one conducting piece retained on the rotor by means of an axially extending bolt.
This construction is particularly simple with respect to the manufacture of the conducting piece assemblies, since no external shoulders, pockets or the like have to be produced, but rather the bolt can be passed e.g. through a drilled or punched hole in the conducting piece assembly. Provision of a bolt in the foot end region of the conducting piece normally is preferred since there the magnetic flux passage is impaired least.
According to a fourth preferred solution of the problem mentioned, the machine according to the invention is characterized in
(d) that the rotor comprises a plurality of thin round plates spaced apart in the direction of the rotor axis, and in that the conducting piece assemblies and/or the permanent magnets are divided into axial partial lengths that are attached to the round plates.
The fourth solution realizes the conception that the forces arising at the conducting piece assemblies and/or the permanent magnets (in particular the forces of magnetic attraction in radial direction and the centrifugal forces) are divided to partial lengths of the conducting piece assemblies and/or of the permanent magnets, so as to dissipate them so to speak in shares. As will be pointed out in more detail hereinafter, there is a number of preferred possibilities of providing the connections between the partial lengths and the round plates, in particular by adhering and clamping them to each other. It is to be understood that the round plates preferably are fixed in the remainder of the rotor structure, e.g. also to the bandage to be described still in more detail hereinafter, and to that location dissipate the holding forces for holding the partial lengths of the conducting piece assemblies and/or the permanent
Ehrhart Peter
Lindner Ludwig
Lucas Christian
Reiner Gerhard
Walter Fritz
Magnet-Motor Gesellschaft für magnetmotorische Technik mbH
Nguyen Tran
Voorhees Catherine M.
LandOfFree
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