The present invention refers to a process for making a continuous winding for a stator of an electric machine and to a winding made with such process.
In particular, the invention refers to a process for making a continuous winding, using a metal slat, for a stator of a rotary electric machine with closed slots.
Known electric machines comprise a fixed part, the stator, and a moving part, the rotor, arranged coaxially one inside the other. Typically, the rotor comprises a pack of sheets fastened onto a rotation shaft, and is inserted inside the stator, which comprises an electric winding adapted to generate a magnetic field which rotates the rotor.
The stator generally is of an annular shape and comprises a plurality of radial slots, inside which the electric winding is made.
For making the electric windings of the stator, it is known to use copper bands, which are bent in their central part to form straps shaped as a hairpin, called “hairpins”, to be inserted in the slots of the stator.
The bending shape and angle of the bands change when the geometry of the stator and of the slots changes, and when the winding scheme changes.
These straps are inserted into the slots of the stator from the same side, with the two terminals of every strap inserted in different slots, according to a certain scheme, to obtain the exact number of coils necessary to compose the desired winding; the ends of the straps which project from the slots are bent with a twisting process, to prevent them from going out, and are then mutually welded, after having removed the insulating material from the welding area, in order to create a correct connection between the different copper straps to form the stator winding.
This known process ends with insulating the welding areas through resins; finally, the stator and the straps are made integral by immersing their ends into a resin.
This known process of making the windings through the use of hairpins has a series of problems, caused by the several welding spots being present in the winding, which cause an increase of the resistance to the passage of current and which require the presence of several quality controls for the welding, by the process complexity, with problems linked for example to the need of insulating the winding with resins, to the process complexity and the limits to the length which can be used for bands, due to the difficulty of inserting it into the stator slots, in particular in the closed slots.
Object of the present invention is solving these problems through a process for making a continuous winding for a stator of an electric machine and a winding made with such process, which allow a drastic reduction of the number of welding being present in the winding, a lower insulation through resins, a reduction of the resistance to the passage of current in the winding, the removal of the twisting process, a reduction of quality controls within the process, make it possible to obtain windings on stators with a greater active lengths, with lower costs, better filling of the slots by the winding and in general a better efficiency of the electric machine being made.
The above and other objects and advantages of the invention, as will result from the following description, are obtained with a process for making a continuous winding for a stator of an electric machine and a winding made with such process as claimed in the independent claims.
Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.
It is intended that all enclosed claims are an integral part of the present description.
It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) can be made to what is described, without departing from the scope of the invention, as appears from the enclosed claims.
The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:
With reference to the Figures, the process for making a continuous winding for a stator of an electric machine of the invention comprises the following steps:
In order to complete the assembling of the stator 15, after the step of insulating the welding, the following steps are provided:
The continuous winding for a stator of an electric machine of the invention will be described below, said stator comprising a first, internal stator part 25 which comprises a plurality of longitudinal teeth 26 spaced by a space 27, said continuous winding comprising at least one strap 11, 21, 31 which comprises a plurality of first sectors 12 mutually connected by a plurality of second sectors 13 alternate thereto, said at least one strap 11, 21, 31 being configured to be wound on the first, internal stator part 25, placing the first sectors 12 of the straps 11, 21, 31 into the spaces 27 included between the teeth 26. In a preferred way, the first sectors 12 are mutually parallel, being every first sector 12 connected at at least one end thereof to a second sector 13, and the winding comprises three, mutually alternated straps 11, 21, 31.
Advantageously, the process for making a continuous winding for a stator of an electric machine of the invention enables a drastic reduction of the number of welding spots present in the winding, a lower insulation through resins, a reduction of the resistance to the passage of current in the winding, the removal of the twisting process, a reduction of quality controls inside the process, and makes it possible to obtain windings on stators with greater active length, with lower costs, better filling of the slots by the winding, and in general a better efficiency of the electric machine being made.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/IT2019/000101 | 11/12/2019 | WO |