Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1994-09-19
1996-03-05
Skudy, R.
Electrical generator or motor structure
Dynamoelectric
Rotary
310235, 310236, H02K 1300
Patent
active
054970423
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a collector for an electric motor and a reinforcing ring therefor.
Collectors for simple applications and slight loads can be formed from lamellas and synthetic resin molding compound alone, the lamellas at the periphery being kept at a distance and held by the molding compound, which also forms an internal, annular base structure and typically consists of a thermosetting material which can be reinforced by glass fibers. At higher electrical, thermal and mechanical loads, however, reinforcing rings have proven to be advisable or necessary. Such reinforcing rings embrace the lamellas on the inside at undercuts of internal cross members. Since the lamellas, due to their function, must be insulated electrically from one another, the reinforcing rings must not make conducting contact with the internal cross members.
For this purpose, metallic reinforcing rings, particularly steel reinforcing rings, with an insulating material on the inside as backing in order to achieve a high strength, but also good insulation, have existed for already a long time. This expensive procedure is, however, not appropriate for modern, large-scale manufacturing.
Furthermore, there have been reinforcing rings, which were carefully distanced from the internal cross members of the lamellas during the pressing of the lamellas with synthetic resin molding compound into a collector so that interstices, into which the synthetic resin molding compound can penetrate, were present between the metallic reinforcing ring and the lamellas. However, bracing and insulation of the lamellas, produced in this way, is unsatisfactory and brings about only slight improvements in comparison to a collector without a reinforcing ring, since the synthetic resin molding compound is unable to maintain the insulating distance and the pressure transfer between the reinforcing ring and the cross members of the lamellas at thermal and mechanical loads, which are critical for the synthetic resin molding compound.
The latter is also true for metallic reinforcing rings, particularly for steel reinforcing rings, which have been provided with an insulating layer of synthetic resin in a painting, dipping or sintering process. When the synthetic resin softens, the insulation threatens to collapse.
Reinforcing rings of a conventional composite material, such as a glass fiber-reinforced plastic, have also proven to be unsatisfactory. The stretching of the glass fibers at higher temperatures and under high mechanical loads leads to a "soft" behavior, in which the lamellas, in their integration into the synthetic resin molding compound, begin to work. This leads, in turn, to frictional heat within the collector, to dimensional inaccuracies in the bearing surface of the collector with higher commutator sparking and higher mechanical stresses as a result of the noncircular running of the collector and the dancing collector brushes.
SUMMARY OF THE INVENTION
It is an object of the invention, to provide a collector and a reinforcing ring, which permit the high mechanical and thermal loading capacity, somewhat like that of the metallic reinforcing ring, particularly the steel ring, to be achieved and utilized and, in particular, the weaknesses of known metallic reinforcing rings and their insulation to be avoided.
It can be seen that the weakness of previous reinforcing rings has been their insulation. Admittedly, it was obvious to build up this insulation in the conventional manner with an underlining or casing and, in particular, to start out from synthetic resins, which can be handled well. However, these cause the collectors to be destroyed at the softening or decomposition temperature of the thermoplastic or thermosetting plastic used. On the other hand, the interpositioning of a supporting ring, which is fitted positively into the reinforcing ring and consists of a material that is resistant to compression even at high working temperatures, is suitable for decisively extending the load-carrying capability and the working range of such a collector
REFERENCES:
patent: 2501502 (1950-03-01), Flecher
patent: 3450914 (1969-06-01), Demerciere
patent: 4056882 (1977-11-01), Letts
patent: 4071796 (1978-01-01), Nippert
patent: 4562369 (1985-12-01), Gerlach
patent: 5124609 (1992-06-01), Nagasaka
patent: 5140213 (1992-08-01), Nettelhoff
Friedrich Nettelhoff Kommanditgesellschaft Spezialfabrik fuer
Skudy R.
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