This application claims priority from German Application Serial No. 10 2005 059 846.3 filed Dec. 15, 2005.
The invention concerns a stator of an electric motor.
From DE 10 2004 001 842 A1, a stator with a stator core is known, which has a plurality of grooves and splines. A winding, consisting of several coils, is fitted into the grooves. To make this possible, the coils are pre-wound in such a manner that they can pass over the splines without problems, while the grooves have parallel sides and the splines widen out at their free ends. One or more coils are arranged in each groove.
From DE 103 08 893 A1, a stator with a stator core is known, in which a plurality of coils are arranged in each groove. The ends of the coils project in the axial direction far beyond the stator core and cross-over one another there.
In the known stators, the coils are arranged in the grooves in such a manner that in the radial and axial direction there are intermediate spaces between them. This allows cooling. The intermediate spaces between the coils, on the one hand, increase the bulk of the stator and, on the other hand, reduce the fullness of the stator grooves. Reduction of the fullness decreases the power density of the machine.
The purpose of the present invention is to provide a stator with a very compact structure, which takes up only little axial and radial space.
According to the invention, the stator consists of a stator core with grooves and splines. Into the grooves fits a winding which, in turn, consists of a plurality of part-windings. The part-windings consist of a plurality of coil groups, which are magnetically equivalent, but have different shapes. A part-winding is formed of a first coil group with a first shape and a second coil group with a second shape, in alternation.
The first coil group is shaped such that the winding heads are at an angle. As its two axial ends. There, it is bent in such a manner that, when fitted into the grooves of the shaped stator core, it extends radially outward. At its winding heads, the first coil group is shaped to match the shape of the stator core, where it extends parallel to the axial end faces of the stator core. The winding heads of the first coil group are shaped to fit around the stator core very snugly, so that their projection distance advantageously corresponds only to the necessary bend radius of the coil group.
In one design, the stator core is slightly recessed in its transition zone from the grooves to the axial end face of the stator core, and is thereby adapted to the bend radius of the coil group. This allows the coil group to fit particularly snugly against the stator core.
The second coil group is only angled at a first winding head. There, it is bent in such a manner that, when fitted in the stator core, it extends radially inward. Its second winding head projects in the axial direction beyond the stator core and beyond the winding heads of the first coil group. At its first winding head, the second coil group is bent so as to extend parallel to a surface of the rotor. Usually, at that end of the rotor, there is a rotor bar whose shape and position depend on the size of a short-circuit ring.
A part-winding for a phase of the electric motor now consists of a plurality of coil groups connected to one another by their electric contact ends. The first and second coil groups consist of one or more coils. In one design, each coil group consists of just one coil. This makes the radial extension of the stator very small. In one design, the coils are also wound from insulated flat wire. In this case, the width of the flat wire corresponds to the width of the groove and the grooves are parallel-sided. This enables the maximum possible groove filling, giving a high power density. Because of the advantageous shaping of the coils at their winding heads, the axial extension of the stator is also small. Owing to their compact shape, the coils are also very simple to make by mechanized means.
The invention will now be described, by way of example, with reference to the accompanying drawings in which:
In a different design, at their transition to the end face 9 of the stator core 1, the grooves 2 are recessed and adapted to the bend radius of coil groups 14, 22. This enables the coils 14, 22 to fit in closer contact with the stator core 1. Once coil groups 6, 7 have been fitted in, the stator core 1 is shaped so as to form the cylindrical stator core 1.
Number | Date | Country | Kind |
---|---|---|---|
102005059846.3 | Dec 2005 | DE | national |