Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-12-03
2001-04-17
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S231000, C310S233000
Reexamination Certificate
active
06218761
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an armature with a flat or plane commutator for an electric motor, especially for driving a fuel supply unit, in which the armature has a plurality of metal segments separated from each other by grooves distributed around its circumference on a front side thereof, which are connected with armature windings and which are each covered with a commutator cover at least on a front side thereof which is soldered to the respective metal segment.
2. Prior Art
This type of armature is described in European Patent Document EP 0 491 904. This armature has metal segments separated from each other by grooves distributed around the circumference on the front side. Each segment is covered on its front side with a commutator cover which is soldered with the segment. The commutator covers are separated from each other by slots which correspond to the grooves separating the segments from each other. When the covers are assembled on the armature, it must be guaranteed that the slots separating them must coincide with the grooves separating the segments so that the covers must be very exactly positioned. The slots between the covers must be formed somewhat wider than the grooves separating the segments to compensate for measurement tolerances of the segments. However the slots between the covers should be formed as small as possible because of operational considerations for the electric motor. Furthermore when the covers are soldered with the segments the solder can enter the grooves between the segments or in the slots between the covers and that can lead to a short circuit between neighboring segments or covers. During the soldering the covers are not fixed so that the covers can take incorrect positions relative to the segments.
Furthermore the side surfaces of the segments pointing in the circumferential direction are exposed, so that a deposit can be formed on the metal segments during operation of the electric motor in a corrosive media. The corrosion product formed can lead to a short circuit between the neighboring segments.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an armature with a flat commutator for an electric motor of the above-described kind that does not suffer from the above-described disadvantages.
These objects, and others which will be made more apparent hereinafter, are attained in an armature with a flat commutator for an electric motor, especially for driving a fuel supply unit, in which the armature has a plurality of metal segments separated from each other by grooves distributed around its circumference on a front side thereof, which are connected with armature windings and which are each covered with a commutator cover at least on a front side thereof which is soldered to the respective metal segment.
According to the invention each commutator cover has a recess on its side facing the armature, in which the associated segment is inserted in a direction of the longitudinal axis of the armature and each commutator cover is connected with its associated segment with solder in the recess.
The armature according to the invention with the flat commutator has the advantage that each cover is exactly positioned relative to the associated segment by the segment inserting itself in its corresponding recess and its position is exactly maintained during the soldering. The grooves between the segments can be comparatively wide, since they are covered after connecting the covers and only slots remain between the covers which can be comparatively small because of the exact positioning of the covers. Furthermore the recesses in the covers guarantee that no solder can enter between the covers or segments.
Especially advantageous embodiments and features are claimed in the dependent claims appended hereinbelow.
In a preferred embodiment the commutator covers at least partially cover the edge surfaces of the metal segments pointing in the circumferential direction and/or the edges surfaces of the metal segments pointing radially inward. In this way the segments are protected from corrosion when the motor is used in the presence of corrosive media.
In another preferred embodiment the recesses or cavities in the commutator covers each have an indentation or depression. Because of this advantageous feature solder cannot flow out of the recess.
REFERENCES:
patent: 5386167 (1995-01-01), Strobi
patent: 5677588 (1997-10-01), Strobl
patent: 5925961 (1999-07-01), Sugiyanma
patent: 5962946 (1999-10-01), Kobman et al.
Ast Christian
Gerhard Albert
Richter Ingo
Lam Thanh
Ramirez Nestor
Robert & Bosch GmbH
Striker Michael J.
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