Patent Application
20080204188
The invention relates to a resistor component for an electric machine with at least one resistor and insulation material, wherein the resistor is surrounded by the insulation material. The resistor component is preferably configured as a hollow cylinder or a hollow cylinder segment, whose radius of curvature essentially corresponds to the radius of curvature of an outer housing of the electric machine. Furthermore, the invention relates to a brush bridge and to an electric machine with such a resistor component.
Resistor components of the generic type are known for example from EP 0 520 191 B1 and DE 195 21 395 A1.
From EP 0 520 191 B1 a brush bridge for a direct current permanent magnetic engine is known, which is made of an electrically insulating material, i.e. of plastics. This brush bridge comprises on its carrier plate a resistor, which has the form of a part of a hollow cylinder. Preferably, the radius of curvature of the resistor corresponds to the radius of curvature of the crankcase, the outer surface of the resistor contacting the inner surface of the crankcase. The form and arrangement of the resistor provide for a good heat dissipation from the resistor to the crankcase. However, the heat conductivity of plastics is limited.
From German published patent application DE 195 21 395 A1 likewise a brush bridge made of plastics is known for a collector engine, which in principle comprises the same arrangement. The heat dissipation of the resistor to the crankcase has been tried to be improved by the resistor being stressed by at least one spring in such a manner that the outer surface of the resistor is pressed to the inner surface of the crankcase. Thus, the improvement of the heat dissipation can be effected only to a small extent, as also in this case the limited heat conductivity of the plastics shall apply.
It is, therefore, the object of the invention to further develop a resistor component of the type initially specified such that the heat dissipation of the resistor is improved. Further, it should be manufactured in simple and economical manner. Further objects of the invention are to provide a brush bridge as well as an electric machine with such a resistor component.
This object is achieved by a resistor component (16, 36) for an electric machine with at least one resistor (1, 21) and insulation material, wherein the resistor (1, 21) is surrounded by the insulation material and the resistor component (16, 36) is preferably formed as a hollow cylinder or a hollow cylinder segment, whose radius of curvature essentially corresponds to the radius of curvature of an outer housing of the electric machine the resistor component (16, 36) comprises a fastening element (12, 32). The object is also achieved by providing a brush bridge with the resistor component or by providing an electric machine with the resistor component.
The resistor component consists of a resistor and insulation material. The resistor is closely surrounded by the insulation material on all sides, the insulation material consisting of several sections, preferably of two sections. Preferably, the sections have the form of a hollow cylinder segment and have the same radius of curvature. The resistor is inserted between the two sections and in the inserted condition it likewise has the form of a hollow cylinder segment. The form of the resistor component provides for a good heat dissipation of the resistor component to an outer housing of an electric machine.
A hollow cylinder segment comprises six surfaces. It has an inner surface and an outer surface, the outer surface being that surface, which rests against the housing of the electric machine. The inner surface is the surface being located opposite to the outer surface. The remaining four surfaces are side surfaces, which limit the inner and the outer surface. Thus, two hollow cylinder segments comprise a total of eight side surfaces. For the resistor being closely surrounded on all sides, preferably connectors are formed at four of the altogether eight side surfaces of the two insulation material hollow cylinder segments. Alternatively, the connectors can be formed at a hollow cylinder segment or distributed at both hollow cylinder segments, e.g. two connectors at each segment. The connectors are formed at right angle along the respective entire side surface and essentially have the same size. If all four connectors are located at one segment, they all direct in one direction. If, however, the connectors are distributed to two segments, they direct into opposite directions. The embedding of the resistor resulting from the connecting pieces provides for a good electric insulation of the resistor.
With at least one fastening element both the insulation material at the resistor and the resistor component are arranged at a further electric component, preferably a brush bridge. The fastening element is formed such that by means of clamp-like formations it surrounds and holds together the hollow cylinder segments, in which the resistor is embedded. Notches are preferably provided at the hollow cylinder segments, which fix the position of the fastening element, in particular of the clamp-like formations. Further, the fastening element serves for arranging the resistor component at a further electric component, in particular a brush bridge. The resistor component is determined particularly for being applied on a brush bridge of a direct current motor. This fastening can be effected for example by a detachable or a non-detachable connection. For this purpose, openings are provided for example at the brush bridge, into which the appropriate counterparts, such as for example retaining noses, of the fastening element, are plugged in. Here it is advantageous, if the fastening element is formed such that it additionally presses the resistor component also to the outer housing of an electric machine.
Preferably, the resistor component comprises electric connectors, lying inside, for the resistor. For this purpose, in particular that hollow cylinder segment, which does not rest against the outer housing of the electric machine, comprises a bulge, which is directed to the center of the further electric component, in particular to the brush bridge. This bulge has two openings, through which the electric connectors for the resistor are plugged and then are connected to the resistor within the bulge in the resistor component. By such connectors lying inside, in particular with electric machines of an open style, signs of wear based on corrosion and/or scaling as well as premature material fatigue of the connectors can be prevented.
Advantageously, distancing and cooling fins, respectively, are formed at least at one hollow cylinder segment, which provide for a further improvement of the heat dissipation of the resistor component.
Preferably, the insulation material is made essentially of ceramics, preferably of polymer ceramics. Polymer ceramics are materials, which comprise the characteristics of the electric insulation ability as well as heat conductivity. However, also other materials than insulation material can be used with the cited characteristics, such as for example temperature-resistant plastics.
The resistor is preferably formed as a meander. Meander-shaped resistors can be manufactured in simple manner by means of punching methods.
Furthermore, a brush bridge for an electric machine comprises a resistor component according to invention. The brush bridge is preferably produced of plastics and is formed such that it comprises different elements for arranging the necessary electric components, such as for example throttles or condensers, and electric fixed contacts. With special advantage the brush bridge is formed such that the resistor component according to invention can be easily installed.
Furthermore, an electric machine comprises a resistor component according to invention. Preferably, the electric machine is a direct current motor. With special advantage the resistor component is suitable as a pre-resistor for the single- or multi-stage speed adjustment of the electric vehicle radiator fan.
In addition, an electric machine comprises a brush bridge with a resistor component according to invention. The brush bridge is preferably produced of plastics and is formed such that it comprises different elements for arranging the necessary electric components, such as for example throttles or condensers, and electric fixed contacts. With special advantage the brush bridge is formed such that the resistor component according to invention can be easily installed.
In the ensuing description the features and details of the invention are described in detail on the basis of examples of embodiment taken in conjunction with the enclosed drawings. Here, features and connections described in individual variants can basically be transferred to all examples of embodiment.
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| Number | Date | Country | Kind |
|---|---|---|---|
| 102005032393.6 | Jul 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DE2006/001163 | 6/4/2006 | WO | 00 | 1/14/2008 |
