Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1998-10-08
2001-02-27
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S049540, C310S043000, C310S091000, C310S254100
Reexamination Certificate
active
06194797
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a method for producing a multipole electric motor, in which a plurality of pole laminations mutually separated magnetically are arranged between the ends of coils and a rotor, as well as to a multipole electric motor having a rotor and having a plurality of pole laminations, which are mutually separated magnetically and extend from the ends of coils to the rotor.
Such a multipole electric motor and a method for producing it are known in practice. The multipole electric motor has in this case two or more coils as stator and, on the rotor, a cylindrical permanent magnet having a plurality of magnetic poles. One pole lamination is guided in each case from one end of one of the coils to the rotor, where it is situated opposite the permanent magnet with a very slight spacing. In the known method for producing the known electric motor, the pole laminations are individually fastened on the ends of the coils, and the coils are subsequently mounted in the housing of the electric motor.
A disadvantage of the known method is that the positioning of the pole laminations with respect to the rotor proves to be very complicated. Furthermore, even slight deviations of the coils from their prescribed position in the housing lead to a faulty spacing of the pole laminations from the permanent magnet of the rotor. In the most unfavorable case, the pole laminations can touch the permanent magnet and lead to blocking of the rotor.
SUMMARY OF THE INVENTION
It is the object of the invention to develop further the method mentioned at the beginning for producing a multipole electric motor in such a way as to permit a particularly simple mounting of the electric motor and to permit the pole laminations to be positioned particularly accurately with respect to the permanent magnet. Furthermore, the aim is to create a multipole electric motor in which the pole laminations are positioned particularly accurately with respect to the permanent magnet.
The first-named problem is solved according to the invention by virtue of the fact that the pole laminations are produced as a component held together via webs and that the pole laminations are fastened in a middle region on a holding part made from plastic, and the webs are subsequently severed between the individual pole laminations.
The component forming the pole laminations can, for example, be produced particularly accurately from sheet steel by stamping and bending. After the component forming the pole laminations has been fastened on the holding part, the pole laminations are fixed between one another, with the result that they remain in their prescribed position after the webs have been severed. After the mounting of the structural unit comprising the holding part and the pole laminations in the electric motor, the pole laminations are aligned particularly accurately with respect to the permanent magnet of the rotor. A further advantage of this configuration is in that the permanent magnet can be produced to be weaker, and thus in a very cost effective fashion owing to the high accuracy with which the pole laminations are positioned. Thanks to the method according to the invention, it is also no longer necessary for the pole laminations to be individually mounted, as in the case of the known method. As a result, the production of the electric motor proves to be particularly cost-effective. The production of the electric motor using the method according to the invention can, moreover, be automated.
The component forming the pole laminations could, for example, be bonded to the holding part. However, the method according to the invention proves to be particularly cost-effective when the component forming the pole laminations is injection-coated or potted by means of solidifiable plastic, and when the severing of the webs of the pole laminations is performed after the solidification of the plastic. After the injection-coating or potting by means of the plastic, the pole laminations are reliably positioned, with the result that they remain in their prescribed position after the webs have been severed.
In accordance with an advantageous feature of the invention, the webs between the pole laminations can be severed with particularly high accuracy when they are cut through by a laser beam. A further advantage of this method is that the laser beam places no mechanical load on those regions of the pole laminations and the plastic which border the break.
The webs could, for example, be arranged in the region provided for the permanent magnet. The laser beam could then subsequently be used to cut out a circle corresponding to the diameter of the permanent magnet, and thus to sever the webs. As a result, however, the sheet-metal part, and thus the bordering regions of the plastic are subjected to a very high thermal load. In order to cut by means of the laser beam, it is possible in accordance with another advantageous feature of the invention to use a particularly weak laser beam of small diameter when webs arranged in lateral regions next to a cutout for a permanent magnet are severed by means of the laser beam at two points in each case. The weak laser beam of small diameter leads only to a very slight thermal loading on the sheet-metal part. Nevertheless, it is possible hereby to produce large spacings of the pole laminations from one another, as a result of which magnetic induction of two neighboring pole laminations is particularly slight, in addition.
In accordance with another advantageous feature of the invention, the webs between the pole laminations can be severed particularly quickly and simultaneously when they are removed by a punching method. In this case, it is even possible, given an appropriate configuration of the punching tool, for all the webs to be severed simultaneously, and to produce the cutout for the permanent magnet of the rotor in the same work operation. This leads to low production costs, in particular, when the electric motor is to be produced in large batch-quantities using the method according to the invention.
The second named problem, specifically the creation of a multipole electric motor, in which the pole laminations are positioned particularly accurately with respect to the permanent magnet, is solved according to the invention by virtue of the fact that the pole laminations are arranged in a common holding part made from plastic in a region facing the rotor.
This configuration provides the electric motor with a structural unit which comprises the pole laminations and the holding part and can be produced particularly accurately outside the electric motor. Consequently, the individual pole laminations are positioned particularly accurately with respect to the permanent magnet, as a result of which the electric motor according to the invention can have a weaker permanent magnet than in the known electric motor and consumes less electric current. Furthermore, the electric motor according to the invention can be mounted in a particularly cost-effective fashion, since it is necessary to mount only a single component despite a plurality of pole laminations mutually separated magnetically.
The pole laminations could, for example, be made of a sintered material. However, in accordance with an advantageous feature of the invention, the pole laminations can be produced in a particularly cost-effective fashion using the punching method and by bending when they are made of galvanized steel sheet. Furthermore, owing to this configuration, the pole laminations have a particularly high corrosion resistance by comparison with non-galvanized steel sheet.
As further advantage, the costs of producing the electric motor according to the invention are reduced when the holding part is constructed as part of a housing of the electric motor.
In accordance with another advantageous feature of the invention, the rotor is positioned particularly accurately with respect to the pole laminations when the holding part has a bearing block for the rotor and/or for a shaft driven by the rotor.
The
Kolibius Hans
Simon Ernst-Ulrich
Zech Stefan
Farber Martin A.
Mannesmann VDO AG
Nguyen Tran
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