WO2007124985A1

WO2007124985A1 - Method and device for producing a bar winding for the stator of an electric machine

Info

Publication number: WO2007124985A1
Application number: PCT/EP2007/052709
Authority: WO
Inventors: Thomas Berger; Christoph Schwarzkopf
Original assignee: Robert Bosch Gmbh
Priority date: 2006-04-26
Filing date: 2007-03-21
Publication date: 2007-11-08
Also published as: DE102006019314A1

Abstract

The invention relates to a method and a device for producing a bar winding (18) for the stator (16) of an electric machine, especially of a claw pole generator for motor vehicles. Said stator has a respective plurality of conducting segments (36) radially superposed in the coil head (45), their ends (42), owing to their shape and/or arrangement, forming a defined fusion zone (40) in the area of contact and being interconnected in pairs by contactless fusion welding. According to the invention, the heat quantity required for melting the fusion zone and the heat transfer to other areas of the winding (18) can be substantially reduced when combining a defined fusion zone in order to strictly delimit the welding area and a contactless welding method.

Description

title

Method and device for producing a bar winding for the stator of an electrical machine

State of the art

The invention is based on a method and a device for producing a bar winding for the stator of an electric machine, in particular a claw-pole generator for motor vehicles, as are known from EP 1 043 828 A. This document discloses a method and a device for contactless welding of the ends of a plurality of conductor segments of the winding of an electrical machine, wherein wedge-shaped metal parts are inserted between the ends to be joined of the conductor segments for positioning the conductor segments and to reduce the heating of the winding during welding. The welding process itself is carried out in a conventional manner by an inert gas welding process.

Disclosure of the invention

The inventive method and apparatus for carrying out the method are characterized by a novel shape and arrangement of the ends to be joined of the conductor segments in the winding of the stator winding, wherein in the contacting region of the conductor segments a defined Melting zone is formed for targeted and thus faster heating of this area, whereby the amount of heat required during the welding process is reduced and thereby the heat load of the remaining coil is reduced.

A first advantageous design possibility for the ends of the conductor segments to be welded results from the fact that the ends are tapered towards the melting zone, whereby the amount of heat required to melt the welding zone can be significantly reduced. Another very advantageous possibility for designing the welding zone according to the invention is that the ends of the conductor segments to be joined form a depression in the melting zone, in which the welding beam is directed toward the melting zone, so that only little loss of heat flows away into the remaining regions of the conductor segments. A further expedient variant of the inventive method is to form the conductor segments to be connected of different lengths, so that in the welding area at the end of the shorter conductor segment gradation in the form of a notch is formed, in which the welding beam can be initiated selectively and with low heat flow to other areas ,

To avoid an electrical short circuit and to reduce the heating of adjacent, uninvolved at the respective welding process conductor segments, it is advantageous if the ends to be connected of the conductor segments are separated in pairs by an insulation from the ends of the neighboring conductors. Such insulation made of heat-resistant plastic or ceramic can be suitably designed band-shaped and after the bending process of the conductor segments in the region of the winding head be introduced into the spaces between the conductor ends to be connected.

With regard to the process engineering embodiment of the contactless welding method, it is furthermore particularly advantageous to use an electron beam or a laser beam as the energy beam or to work with a TIG (tungsten inert gas) welding method, in particular with a micro plasma method with a pilot arc for igniting the welding arc. In this case, the use of an electron beam as an energy beam offers the advantage of a low influence of the structure in the welding zone. The laser beam as an energy beam offers the advantage that with low energy input and thus low thermal stress of the environment of the weld zone a safe

Welded joint with sufficient depth of the molten zone is achieved.

The TIG welding process, in particular in the form of plasma welding, offers the advantage of a cost-effective, contactless welding process with high heat output and thus short welding time, the protective gas sheath shielding the melting zone from the atmosphere and thus from undesired reactions, in particular against oxidation in the melting zone. In this case, the micro-plasma process offers the possibility of bundling the welding energy particularly precisely and tightly and thus reducing the heat load on the material surrounding the welding region. By using a torch with pilot arc, the ignition of the actual arc is facilitated and accelerated.

The material application and the heating of the welding area are further improved and accelerated when the During welding, the energy beam is directed onto an additional material which, when dripping onto the welding region, further accelerates the welding process by virtue of its residual heat, in addition to the primary heating of the welding region.

Brief description of the drawings

Exemplary embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. Show it

1 is a perspective view of a stator with a bar winding with preformed for the welding process ends of the conductor segments,

2 shows a partial section through the laminated core of the stator with radially extending grooves, each with four conductor segments arranged one above the other, FIG.

3a is a schematic sectional view with four in the winding head of the stator arranged one above the other, in pairs welded conductor segments,

3b is a schematic representation of a wave winding with a welded connection of a conductor pair,

4 shows an arrangement with four conductor segments arranged radially one above the other in the winding head and to be connected in pairs with each other and tapered in the welding region, Fig. 5 shows an arrangement with six radially arranged in the winding over each other and in pairs to be joined together conductor segments, which in the welding area a recessed

To form the melting zone,

6 shows an arrangement with four conductor segments arranged one above the other in the winding head and to be connected in pairs, whereby conductor segments of different lengths in the welding region form a step-shaped melting zone in the form of a notch, FIG.

Fig. 7 shows an arrangement according to FIG. 6, wherein in

Welding area a filler material is introduced into the welding beam, and

Fig. 8 shows an arrangement of the conductor segments according to Figures 6 and 7, wherein the contactless

Weld by one

TIG plasma welding device with Zundlichtbogen done.

Embodiments of the invention

Fig. 1 shows a perspective, schematic representation of a stator 16 of an electric machine, as used for example in a Klauenpolgenerator for motor vehicles. On the inner surface of the stator 16 are poles 32 and grooves 34 can be seen, in each of which four conductor segments 36 are arranged radially one above the other. The conductor segments are bent in a known manner on the underside of the stator 16 haarnadelformig and limited by one pole pitch. Their equally long, free ends 42 protrude at the top of the stator 16, also limited by a pole pitch, out of the grooves 34 and are arranged in four concentric rows. This is after the assembly of electrical

Machine, the free ends 42 in the drive-side winding head 45 of the stator, while the haarnadelformigen deflections 44 protrude at the opposite end winding 46 of the stator 16, which is aligned after the assembly of the electric machine to the wiring side. This arrangement has the advantage that 45 more space for the welded joints is available in the drive-side winding head. The machine axis is designated 27.

Fig. 2 shows an enlarged view of a section through the laminated core 17 of the stator 16, wherein in each groove 34 four conductor segments 36 are arranged radially one above the other. The conductor segments are on the one hand on its surface by a paint insulation 38 and on the other hand together insulated by insulating inserts 39 against the laminated core 17 of the stator 16. The introduction of the conductor segments 36 of the stator winding 18 designed as a bar winding takes place by axial insertion of the conductor segments 36 into the grooves 34.

Fig. 3 shows in the figure a in schematic form a partial section through the laminated core 17 of the stator 16, from which the free ends 42 of the stator winding 18 protrude. The ends 42 of the stator winding 18 are freed from the paint insulation 38 in the front region 43. Between the not to be welded ends 42 of the

Conductor segments 36 is a distance d leave, in addition, a band-shaped insulation 48 can be introduced, for example, a plastic or ceramic tape. FIG. 3 b shows the hairpin-shaped deflection 44 between the conductor segments 36 in the region of the winding head 46, the spreading of the conductor segments 36 about a pole pitch and the clogging of the free ends 42 towards the welding regions. Other conductor segments are indicated by dashed lines. The inventive welding of the ends 42 with the various possibilities of the design and the arrangement of the ends 42 in the welding area will be discussed in more detail with reference to the following figures.

Fig. 4 shows an arrangement with four radially on the drive side winding head 45 arranged one above the other and to be welded together conductor segments 36 whose stripped ends 43 protrude equally far from the laminated core 17 of the stator 16 and at the same height in the winding head

45 end. Between the non-welded ends 42,43 an insulation 48 is inserted, which is removed after welding the ends 43 in the axial direction. The individual conductor segments 36 are denoted by I, II, III, IV, wherein the conductor segments I and II, or III and IV are welded together in the molten zone 40. The respective ends 43 to be welded are beveled on the outside at an angle of 30 ° to 70 °, preferably at an angle of 45 ° and thereby correspondingly curved in cross section, so that the melting zone 40 is reduced and the energy required for the melting of the zone 40th can be reduced. The energy beam is denoted by 52, the energy source by 54. This is either an electron beam source and an electron beam or a laser source and a laser beam, which are used for contactless fusion welding. With very good results for the melting and welding of the ends 43 in the region of the melting zone 40 can also be a Plasma welding method can be used, as explained with reference to FIG. 8 closer.

Between the conductor segments II and III, an insulation 48 is inserted, on the one hand ensures the distance between the electrically non-contacting conductor segments 36 and forms a protection against an electrical turn and against thermal stress of the adjacent segment during welding. The forces exerted by a clamping device, not shown, during the welding process for positioning and locking the conductor segments are indicated by the arrows 50 and 56. In the axial direction, no forces act on the conductor segments 36 in the inventive contactless welding, so that the conductor segments do not have to be clamped in this direction.

Fig. 5 shows an arrangement with six in the drive-side winding head 45 radially superposed conductor segments 36, which are marked with I-VI. In the front region of the conductor segments 36, as in the remaining arrangements, the paint insulation 38 shown in the drawings by reinforced lines is again removed. The ends 42 are bevelled in the arrangement of FIG. 5 inwardly so that they kerbformige

Form recess as a melting zone 40. At the center of this depression, the energy beam 52 emitted by the energy source 54 is directed, again in this case as an electron beam or as a laser beam. Since in this embodiment, three pairs of conductor segments 36 are arranged one above the other, each one insulation 48 is located between the conductor segments II and III or IV and V. The resulting melt zones 40 are concave in this case and curved inwards. Fig. 6 again shows an arrangement with four in the drive-side winding head 45 arranged radially one above the other and to be welded together conductor segments 36, wherein the two middle segments II and III further protrude from the laminated core 17 of the stator 16 as the outer segments I and IV Welding of the conductor segments by the electron or laser beam 52 takes place here in the contacting region at the end of the shorter conductor segments I and IV at the bottom of the notch formed by the grading, in which the energy beam obliquely, approximately in the direction of the bisector occurs, in the exemplary embodiment with straight leading edges So at an entrance angle of about 45 °. This results in a melting zone 40, as drawn in the lower part of the figure at the front end of the conductor segment IV. The lacquer insulation 38 has also been removed here before the welding in the region of the ends 42, the insulation between the conductor segments II and III is again by the insertion of an insulation 48th

However, to weld the ends 42 of the conductor segments I and II, or III and IV, an additional material 58 is additionally provided in the region of the step at the end of the shorter conductor segment I or IV introduced in wire or rod form in the energy beam 52 and continuously nachgeschoben. The filler material is melted by the energy beam 52 and drips off to the melt zone 40. The residual heat of the melt helps in this process known as "droplet" process to heat the melting zone 40 and simultaneously accelerates the welding process by the application of material, so that less heat flows into the winding area and the insulation 48 correspond to the embodiment in the preceding figures.

Fig. 8 shows an arrangement with a water-cooled TIG (tungsten inert gas) welding device. This contains in the middle a non-consumable tungsten electrode 60 which is connected when welding conductor segments 36 made of copper as the cathode and connected to the ground terminal of a DC voltage source, while the conductor segments to be welded connected as the anode and the positive pole of the

DC voltage source are connected. In this case, a protective gas jacket of argon or helium or a mixture of the two gases covers the arc 62 between the electrode 60 and the molten zone 40 and at the same time protects the molten zone through the protective gas jacket against reactions of the melt with the surrounding atmosphere, in particular against oxidation. The arc 62 is initially ignited at the beginning of the welding process as an auxiliary arc to accelerate the formation of the actual welding arc (micro-plasma welding). The plasma nozzle 64 surrounding the tungsten electrode 60 is water-cooled. The exit of the protective gas is indicated by arrows 66. As with the previous arrangements, an additional material can also be introduced into the melting zone 40 in this method, the illustration of which has been dispensed with.

Claims

claims

1. A method for producing a bar winding (18) for the stator (16) of an electrical machine, in particular a claw pole generator for motor vehicles, each having a plurality in the winding head (45,46) radially superimposed conductor segments (36) whose ends (42) form a defined melting zone (40) by their shape and / or arrangement in the contacting region and are connected in pairs by a contactless fusion welding process.

2. The method according to claim 1, characterized in that the ends to be joined (42) of the conductor segments (36) to the melting zone (41) are tapered out (Fig. 4).

3. The method according to claim 1, characterized in that the ends to be joined (42) of the conductor segments (36) in the molten zone (41) form a depression (Fig. 5).

4. The method according to claim 1, characterized in that the conductor segments to be connected (36) are of different lengths and in the contacting region at the end of a shorter conductor segment (1, IV) form a stepped melting zone (40) (Fig. 6-8)

5. The method according to any one of the preceding claims, characterized in that the ends to be joined (42) of the conductor segments (36) in pairs by one after the Welding removable insulation (48) from the ends (42) of the adjacent conductor segments (36) are separated.

6. The method according to any one of the preceding claims, characterized in that an electron beam is used as the energy beam when contactless welding (Fig. 6 and 7).

7. The method according to any one of claims 1-5, characterized in that the energy beam when contactless welding a laser beam is used (Fig. 6 and 7)

8. The method according to any one of claims 1-5, characterized in that as a contactless welding process, a TIG (tungsten inert gas) welding process is used (Fig. 8).

9. The method according to claim 8, characterized in that a micro-plasma method with a pilot arc is used as the welding method (Fig. 8).

10. The method according to any one of claims 6-9, characterized in that the energy beam is directed at contactless welding on a filler material which drips onto the weld (40) (droplet method, Fig. 7).

11. An apparatus for carrying out a method according to claim 1, characterized by the use of an electron beam source for heating the molten zone (40).

12. An apparatus for carrying out a method according to claim 1, characterized by the use of a laser source for heating the molten zone (40).

13. A device for carrying out a method according to claim 1, characterized by the use of a water-cooled plasma welding device with pilot arc between the welding electrode and the conductor segments to be connected (36).