FR2573258A1 - Stator for electrical machines and machines provided with said stator - Google Patents

Abstract

This stator for electrical machines including a magnetic flux-return body and at least one permanent magnet most commonly made from a sintered magnetic material and in close contact with the inner surface of the magnetic body is notable in that it consists of a shell 14 composed of a magnetic metallic section, such as a thin steel strip, wound continuously around a cradle 1 of non-magnetic material via which the magnets are previously positioned.

Description

 The present invention relates to a stator for electric machines co-carrying a magnetic flux return body and at least one permanent magnet, most commonly made of sintered magnetic material.

 Usually, such a stator is assembled by fixing the magnets in the casing body so that they always apply tightly against the interior surface either by means of elastic orgar.es or by gluing, which casing may have a cylindrical or rectangular cross section.

 The dimensions of permanent magnets produced by compression vary within relatively wide limits. This is also the case for the diametrical dimensions of the inner surface of the casing advantageously obtained by rolling or folding.

 These additive variations contribute to obtaining an inductor / armature gap of the machine which can be relatively large, greatly influencing its performance.

 The invention aims to provide an electric machine stator whose design is such that it easily accommodates magnets with large thickness tolerances and ignores the internal diameter of the magnetic body.

 Furthermore, this stator can be obtained by fully automated assembly means consequently reducing its time of obtaining.

 It therefore relates to a stator for electric machines comprising a magnetic flux return body and at least one permanent magnet most commonly made of sintered magnetic material and in close contact against the interior surface of the magnetic body characterized in that it is consisting of a casing composed of a magnetic metal profile wound continuously around a cradle of non-magnetic material through which the magnets are previously positioned.

 In a first embodiment of the invention, the magnetic metal profile is a strip of thin strip.

 In a second embodiment, the magnetic metal profile is a wire.

 Other characteristics and advantages of the invention will emerge during the description which follows, made with reference to the appended drawings in which FIG. 1 is a perspective view of the non-magnetic cradle.

Figure 2 is a perspective view of the cradle of Figure 1
in which the magnets are positioned before the magnetic body is wound.

Figure 3 is a cross section of Figure 2 along the
line 3-3.

Figure 4 is a perspective view of the stator obtained conformed
ment to a first embodiment of the invention.

FIG. 5 is a perspective view of the stator obtained according to a
second embodiment of the invention.

 The stator according to the invention is produced from a cradle 1 (fig. 1) made of non-magnetic material such as plastic comprising two frontal cheeks 2,3, connected by two pairs of parallel beams 4,5 and 6,7, each pair associated with the two cheeks (2,3) delimiting a housing 8,9 into which each of the magnets read, 11 facing each other is inserted and at a distance such as to determine the chosen air gap.

 The magnets 10,11 in radial abutment on the edges 12,13 formed along the beams 4,5 and 6,7 are self-held in place by their respective attraction (fig. 2 and 3).

 In accordance with a first embodiment shown in FIG. 4, the magnetic body is composed of a strip of strip 14 which is thin and of width approximately equal to the desired casing determined by the distance between the two cheeks (2,3 ) is continuously wound around the cradle 1, in close connection with the outer surfaces îOa, lla of the magnets 10,11.

 To achieve this winding, the cradle 1 is arranged and held by the magnetic attraction of the magnets 10,11 on a mandrel (not shown) biased in rotation.

 Once the winding has been carried out, by a number of turns determined by the thickness of the strip and by ~ the thickness of the casing S obtained, the strip of strip 14 is cut and its end is held by electric welding spots 15.

 The embodiment shown in FIG. 5 differs essentially from the previous one in that the magnetic metallic profile is in the form of a wire 16 wound continuously around and along the longitudinal members 4.5 and 6.7 of the cradle 1, in close connection with the outer surfaces 10a, 11a of the magnets 10, 11.

 The coil thus produced has a number of turns which is determined by the section of the wire and the dimensions of the casing to be obtained.

Claims (3)

 1.- A stator for electric machines compacting a magnetic flux return body and at least a permanent magnet most commonly made of sintered magnetic material and in close contact against the inner surface of the magnetic body, characterized in that it consists of a casing (14,16) composed of a magnetic metal profile wound continuously around a cradle of a non-magnetic material through which the magnets are previously positioned  2 stator according to claim 1 characterized in that the cradle 1 produced by molding a plastic spinner comprises two front cheeks (2,3) connected by two pairs of parallel beams (4,5) and (6,7) each pair associated with said cheeks delimiting a housing (8,9) into which each of the magnets (10,11) is inserted until it comes radially into abutment on edges (12,13) formed along the side rails (4,5) and (6,7).  3.- Stator according to claims 1 and 2 characterized in that the magnetic metal profile is in the form of a strip of thin strip whose width is equal to the length of the casing (14) to be obtained and delimited by the distance between the two cheeks (2,3).  h.- stator according to claims 1 and 2 characterized in that the magnetic metal profile is in the form of a wire (16).