METHOD FOR PRODUCING AN ACTIVE PART FOR A ROTATING ELECTRIC MACHINE, ACTIVE PART FOR A ROTATING ELECTRIC MACHINE AND ROTATING ELECTRIC MACHINE

Method for producing an active part (1) for a rotating electric machine (101), comprising the following steps:          providing a core (2) for the active part (1) and shaped conductors (6) which are inserted into the core (2),     joining in each case two of the end faces (9) to one another; and     welding a respective pair (10) of the end faces (9) by means of a laser beam which is guided along a pattern having a trajectory (15).

The invention relates to a method for producing an active part for a rotating electric machine, comprising the following steps: providing a core for the active part and shaped conductors which are inserted into the core, wherein the core has an end side, a further end side which is situated opposite the end side and a plurality of slots which are arranged in the circumferential direction and in which the shaped conductors are arranged, wherein the shaped conductors extend from the end side to the further end side and each have a free end which protrudes at the end side and has an end face; joining in each case two of the end faces to one another, so that the two end faces form a pair, wherein an edge of the end face of a respective shaped conductor consists of an inner edge portion and an outer edge portion, wherein the inner edge portion of the end face of one shaped conductor of a respective pair runs along the inner edge portion of the end face of the other shaped conductor of the pair and a boundary region runs between the inner

edge portions; and welding a respective pair of the end faces by means of a laser beam which is guided along a pattern having a trajectory over an area on the edge of which the outer edge portions lie and which includes the boundary region.

In addition, the invention relates to an active part or a rotating electric machine and to a rotating electric machine.

WO 2019/159737 A1 discloses coil segments which are inserted into a core. End portions of the coil segments are joined to one another and surfaces of the end portions, which surfaces form an area with a boundary, are irradiated and welded by means of laser light. The laser light is guided over a rectangular trajectory.

When welding end portions of shaped conductors which are inserted into a core, it is necessary to form a stable and electrically highly conductive welded connection.

Furthermore, an input of energy into the end faces which is as low as possible should be performed in order to prevent the coating of coated shaped conductors from melting.

The invention is based on the object of specifying an improved way of producing an active part for a rotating electric machine compared to the prior art.

According to the invention, this object is achieved in the case of a method of the kind mentioned at the outset in that an energy of the laser beam on the area is input into the respective pair by the guidance along the pattern asymmetrically with respect to a line of symmetry which runs along the boundary region or perpendicularly to the boundary region.

The method according to the invention for producing an active part for a rotating electric machine comprises a step of providing a core for the active part and shaped conductors. The shaped conductors are inserted into the core. The core has an end side. The core has a further end side. The further end side is situated opposite the end side. The core has a plurality of slots. The slots are arranged in the circumferential direction. The shaped conductors are arranged in the slots. The shaped conductors extend from the end side to the further end side. The shaped conductors each have a free end. The free end protrudes at the end side. The free end has an end face. The method according to the invention further comprises a step of joining in each case two of the end faces, so that the two end faces form a pair. An edge of the end face of a respective shaped conductor consists of an inner edge portion and an outer edge portion. The inner edge portion of the end face of a shaped conductor of a respective pair runs along the inner edge portion of the end face of the other shaped conductor of the pair. A boundary region runs between the inner edge portions. The method according to the invention further comprises a step of welding a respective pair of the end faces by means of a laser beam. The laser beam is guided over an area along a pattern. The pattern has a trajectory. The outer edge portions lie on an edge of the area. The area includes the boundary region.

An energy of the laser beam is input onto the area by the guidance along the pattern asymmetrically with respect to a line of symmetry. The line of symmetry runs along the boundary region or perpendicularly to the boundary region.

Owing to the asymmetrical energy distribution proposed according to the invention, the input of energy into the free ends of the shaped conductors can be adapted to the geometry of said shaped conductors, so that both corner regions of the area and also the edge and the centre of the area can be melted in as optimum a manner as possible. As a result, a precise weld seam, welding area or welding bead which utilizes the material of the end portions in an efficient manner can be formed.

The core is preferably formed from a large number of layered individual laminations and/or individual laminations which are electrically insulated from one another. In this respect, the core can also be referred to as a laminated core. The slots can be designed as passage openings through the core which extend from the end side to the further end side.

The shaped conductors are preferably formed from copper. The shaped conductors can be designed as a multiply bent wire which has, in particular, a U shape or a V shape. The shaped conductors can have a further tree end which is situated opposite the free end, protrudes at the end side and likewise has an end face. The free ends preferably protrude from different slots at the end side. One or more current paths is or are preferably formed by welding different shaped conductors to one another. The current paths are designed to generate a magnetic field for generating an electromotive force of the rotating electric machine during energization.

The shaped conductors can have a rectangular or rounded rectangular cross-sectional area at the or a respective free end. The cross-sectional area can have two longitudinal sides which are situated opposite one another and two narrow sides which are situated opposite one another. The end faces are preferably joined to one another in such a way that respective longitudinal sides of the shaped conductors of the pair face one another. The area can be delimited, at least in portions, by the narrow sides and/or by the longitudinal sides which do not face one another. The boundary region is typically formed by a gap between the inner edge portions or contact with the inner edge portions.

The shaped conductors can have an outer electrically insulating surface layer which surrounds an electrically conductive material of the shaped conductors. Provision can be made for the electrically conductive material to be exposed at the free end or at the free ends, so that the surface layer is not damaged by the laser beam during welding.

In a preferred refinement of the method according to the invention, the pattern further has a second trajectory. The abovementioned trajectory can also be referred to or considered to be a first trajectory in this respect.

The asymmetrical power distribution can be implemented in particular by way of the second trajectory running asymmetrically to the first trajectory with respect to the line of symmetry.

In the case of the method according to the invention, provision can also be made for the pattern to have a third trajectory. In order to adequately melt regions of the area which are situated outside the first and the second trajectory, provision can be made for the third trajectory to surround the first and the second trajectory. As an alternative, the third trajectory can run between the first and the second trajectory without overlapping. In this case, an imaginary connecting line, which connects the first trajectory and the second trajectory, can intersect the third trajectory once or twice.

The third trajectory can have a start point and an end point, and in particular run in a straight line between the start point and the end point. However, it is also possible for the third trajectory to be a closed trajectory.

The first trajectory can run in a closed manner. The first trajectory runs, in particular, in a circular, oval or rectangular manner. As an alternative or in addition, the second trajectory can run in a closed manner. The second trajectory can then run in a circular, oval or rectangular manner.

Closed trajectories can have a start point and an end point. The start point and the end point can be identical. It is also possible for the start point and the end point to be different and for the trajectory to overlap in portions.

It is possible for the first trajectory and the second trajectory to run on different sides of the line of symmetry. Therefore, the input of energy can be distributed between both sides of the line of symmetry. The first trajectory and the second trajectory particularly preferably additionally run on different sides of a line which divides the line of symmetry perpendicularly, in particular centrally. As a result, the first and the second trajectory can effectively cover two diagonally opposite corner regions. In other words, the first and the second trajectory can run in quadrants of the area which are situated diagonally opposite.

According to a particular refinement, provision can be made for the second trajectory to run in a closed manner over both sides of the line of symmetry and the first trajectory to run, in particular diagonally, within the second trajectory and intersect the line of symmetry. The first trajectory can then run either—as described above—in a closed manner or have a start point and an end point and in particular run in a straight line between the start point and the end point.

As an alternative to the use of closed trajectories, provision can be made for the first and the second trajectory to each have a start point and an end point which is different therefrom.

Here, the first and the second trajectory can each describe an arched curve, in particular an arc of a circle, an arc of an ellipse, a parabola or a hyperbola, on the area. As an alternative, the first and the second trajectory can each have or consist of a first to third straight portion, wherein the first straight portion extends from the start point, the third straight portion extends in the direction of the end point and the second straight portion connects the first straight portion to the third straight portion. The second straight portion can form a right angle with both the first straight portion and the third straight portion. It is also possible for the second straight portion to be able to form a respective angle of more than 90°, for example at least 100°, preferably at least 120°, particularly preferably at least 130°, with the first straight portion and the third straight portion.

In one development, provision can be made for the first and the second trajectory to run with mirror-image symmetry with respect to a line which is shifted in parallel in relation to the line of symmetry.

As an alternative or in addition to an asymmetrical course of the trajectories, provision can be made for the energy intensity of the laser beam along the first trajectory to be greater or smaller than along the second trajectory.

According to a further refinement, provision can be made in the case of the method according to the invention for the trajectory to have a start point and an end point, which is different therefrom, and intersect the line of symmetry between the start point and the end point at least twice, preferably at least four times. The course of the trajectory can be, in particular, meandering. In one development, the second trajectory can have a start point and an end point, which is different therefrom, and run, in particular in a straight line, entirely on one side of the line of symmetry. In addition, the pattern can further have a third trajectory which has a start point and an end point, which is different therefrom, and runs, in particular in a straight line, entirely on the side of the line of symmetry on which the second trajectory does not run. The energy intensity of the laser beam along the second and/or the third trajectory can be greater than along the first trajectory.

In the case of the method according to the invention, a laser device which generates the laser beam can be used which can be operated in a deactivated state, in which the laser beam is turned off or has an insufficient power for melting a material of the shaped conductors, and in an activated state, in which the laser beam can melt the material of the shaped conductor. Here, the welding step can comprise the following steps for a respective trajectory: aligning the reader device with the start point of the trajectory in the deactivated state; guiding the laser beam from the start point, along the trajectory, to the end point of the trajectory in the activated state of the laser device; wherein the laser device is moved from the deactivated state to the activated state between the alignment and the guidance when the laser device is aligned with the start point of the trajectory, and is moved from the activated state to the deactivated state when the guidance has reached the end point of trajectory.

The active part may be a stator or a rotor. The rotor is, in particular, externally excited. The rotor can, in particular, also be permanently excited.

The object on which the invention is based is further achieved by an active part for a rotating electric machine, obtained by the method according to the invention and/or comprising: a core and shaped conductors which are inserted into the core, wherein the core has an end side, a further end side which is situated opposite the end side and a plurality of slots which are arranged in the circumferential direction and in which the shaped conductors are arranged, wherein the shaped conductors extend from the end side to the further end side and each have a free end which protrudes at the end side and has an end face, wherein in each case two of the end faces are joined to one another so that the two end faces form a pair, wherein an edge of the end face of a respective shaped conductor consists of an inner edge portion and an outer edge portion, wherein the inner edge portion of the end face of one shaped conductor of a respective pair runs along the inner edge portion of the end face of the other shaped conductor of the pair and a boundary region runs between the inner edge portions, wherein a respective pair of the end faces is welded by means of a laser beam which is guided along a pattern having a trajectory over an area on the edge of which the outer edge portions lie and which includes the boundary region, wherein an energy of the laser beam on the area has been input into the respective pair by the guidance along the pattern asymmetrically with respect to a line of symmetry which runs along the boundary region or perpendicularly to the boundary region.

The object on which the invention is based is further achieved by a rotating machine comprising a first active part according to the invention and a second active part, in particular according to the invention, wherein the electric machine is designed to drive a vehicle. The vehicle may be a hybrid vehicle or a battery-electric vehicle.

All of the embodiments relating to the method according to the invention can be analogously transferred to the active part according to the invention and the rotating electric machine according to the invention, and therefore the above-described advantages can also be achieved by said active part and said rotating electric machine.

FIG.1shows a diagrammatic sketch of a first exemplary embodiment of an active part1for a rotating electric machine101(cf.FIG.10).

The active part1comprises a core2which can be formed in a generally known manner from a large number of layered individual laminations (not shown) which are electrically insulated from one another and in this case can also be regarded as a laminated core. The core2has an end side3and a further end side4which is situated opposite the end side3. Furthermore, a plurality of slots5which are arranged in the circumferential direction are formed in the core2, which slots extend from the end side3to the further end side4in the axial direction and axially pass through the core2entirely. Only two of the slots5are illustrated, purely schematically, inFIG.1.

The active part1further comprises a plurality of shaped conductors6which are inserted into the core2, only one single shaped conductor from amongst said plurality of shaped conductors being illustrated inFIG.1. The shaped conductors6extend from the end side3to the further end side4and each have a free end7. In the present exemplary embodiment, the shaped conductor6is formed, by way of example, from copper and by a multiply bent wire. In this case, the conductor6extends from the free end7on the end side3, in the axial direction, to the further end side4, has a 180° bend at the further end side4and extends back from the further end side4, through another slot5, to the end side3. The shaped conductor6has a further free end7′ at the end side3. The shaped conductor6accordingly has a U shape or V shape and can also be regarded as a conductor segment of a hairpin winding. The shaped conductors form purely schematically illustrated end windings8at both end sides3,4.

FIG.2is a view of a detail of two shaped conductors6in the region of their free ends7according to the first exemplary embodiment.

Said figure shows that the shaped conductors6protrude from the core2at its end side3. The free ends7each have an end face9which extends substantially perpendicularly to the axial direction or perpendicularly to the direction of extent of the shaped conductors. The end faces9are joined together in order to form the pair10. A gap between the end faces9or contact between the end faces9forms a boundary region11here.

Each pair10of the end faces9are welded to one another by means of a laser beam, so that the free ends7or the shaped conductors6are electrically conductively and mechanically connected to one another. One or more current paths is or are formed by the welding, which current paths are designed to generate a magnetic field for generating an electromotive force of the rotating electric machine101(seeFIG.10) during energization.

FIG.2further schematically shows, using hatching, an outer electrically insulating surface layer12of the shaped conductors6. The surface layer12surrounds an electrically conductive material of the shaped conductors6. The electrically conductive material is exposed only at the free ends7,7′, so that the surface layer12is not damaged by the input of thermal energy of the laser beam.

FIG.3is an end-side view of the end faces9of one of the pairs10according to the first exemplary embodiment.

As is shown inFIG.3, an edge13of the end face9of a respective shaped conductor6consists of an inner edge portion14aand an outer edge portion14b. The start and the end of the inner edge portion14aare marked by arrows P1, P2inFIG.3. The inner edge portion14aof the end face9of a shaped conductor6of a respective pair10runs along the inner edge portion14aof the end face9of the other shaped conductor6of the pair10. The boundary region11runs between the inner edge portions14a.

The pair10is welded by means of a laser beam which has been guided along a pattern, which has a first trajectory15, a second trajectory16and a third trajectory17, over an area18. The outer edge portions14bof the pair10lie on an edge19of the area18. The area18also includes the boundary region11.

An energy of the laser beam on the area18has been input into the respective pair10by the guidance along the pattern asymmetrically with respect to a line of symmetry20which runs along the boundary region.

In the present exemplary embodiment, the trajectories10are each closed trajectories, wherein the first trajectory15and the second trajectory16are circular. The third trajectory17is oval or elliptical. On account of the first trajectory15and the second trajectory16running on different sides of the line of symmetry20and also on different sides of a line21which divides the line of symmetry20centrally, the second trajectory15runs asymmetrically to the first trajectory16with respect to the line of symmetry20. Here, asymmetrically with respect to the line of symmetry20relates to a lack of mirror-image symmetry.

The line of symmetry20and the line21divide the area into four quadrants22a,22b,22c,22dwhich, when looking at the pair10from the end side, are designated in order in the anticlockwise direction. Here, the first trajectory15lies entirely in the second quadrant22b.The second trajectory16lies entirely in the fourth quadrant22d.

In the present exemplary embodiment, the third trajectory17surrounds the first and the second trajectory15,16and makes contact with the first and the second trajectory15,16in so doing. The third trajectory17extends over all four quadrants22a-dand extends diagonally beyond the first and the second trajectory15,16.

The active part1can be designed as a stator102or as a rotor103(cf.FIG.10).

Further exemplary embodiments of the active part1are described below. Here, identical or equivalent components are provided with identical reference signs.

FIG.4is an end-side view of the end faces9of one of the pairs10according to a second exemplary embodiment of the active part1to which all of the embodiments relating to the first exemplary embodiment can be transferred, apart from the differences described below. In the second exemplary embodiment, the third trajectory17runs between the first trajectory15and the second trajectory16without overlapping. An imaginary connecting line23, which connects the first trajectory15and the second trajectory16, intersects the third trajectory17twice.

FIG.5is an end-side view of the end faces9of one of the pairs10according to a third exemplary embodiment of the active part1to which all the embodiments relating to the second exemplary embodiment can be transferred, apart from the differences described below. In the third exemplary embodiment, the third trajectory17has a start point17aand an end point17bwhich is different therefrom, the third trajectory17running in a straight line between said start point and end point. The connecting line23intersects the third trajectory17only once.

FIG.6shows an end-side view of the end faces9of one of the pairs10according to a fourth exemplary embodiment of the active part1to which all the embodiments relating to the first exemplary embodiment can be transferred, apart from the differences described below.

In the fourth exemplary embodiment, the first trajectory15has a start point15aand an end point15b,the first trajectory running in a straight line between said start point and said end point and said start point and said end point lying in non-adjacent quadrants22b,22d.The start point15alies in the second quadrant22b.

The end point lies in the fourth quadrant22d.The first trajectory15extends through the point of intersection of the line of symmetry22with the line21.

According to the fourth exemplary embodiment, the second trajectory16is a closed trajectory which runs in a rectangular manner. The second trajectory16runs both with mirror-image symmetry with respect to the line of symmetry20and also with mirror-image symmetry with respect to the line21. The first trajectory15runs diagonally and without overlapping within the second trajectory16. The second trajectory16intersects the line of symmetry20and the line21twice in each case.

A closed third trajectory is not provided in the fourth exemplary embodiment,

FIG.7shows an end-side view of the end faces9of one of the pairs10according to a fifth exemplary embodiment of the active part1to which all the embodiments relating to the first exemplary embodiment can be transferred, apart from the differences described below.

In the fifth exemplary embodiment, both the first trajectory15and also the second trajectory16each have a start point15a,16aand an end point15b,16b,which is different therefrom, and describe a arched curve, for example an arc of a circle, an arc of an ellipse, a parabola or a hyperbola, on the area18. The first trajectory15and the second trajectory16run on different sides of the line of symmetry20and each intersect the line21. The first trajectory15lies in the second and the third quadrant22b,22c.The second trajectory16lies in the first and the fourth quadrant22a,22d.

The first and the second trajectory15,16run asymmetrically with respect to the line of symmetry20in such a way that they run with mirror-image symmetry with respect to a line24which is shifted in parallel in relation to the line of symmetry20. Furthermore, the energy intensity of the laser beam along the first trajectory15is lower than along the second trajectory16. Therefore, in spite of the identical extent of the trajectories15,16, the asymmetrical input of energy with respect to the line of symmetry20can be performed. The greater energy intensity is represented by a greater line thickness in the case of the trajectory16.

FIG.8is an end-side view of the end faces9of one of the pairs10according to a sixth exemplary embodiment of the active part1to which all the embodiments relating to the fifth exemplary embodiment can be transferred, apart from the differences described below, hi the sixth exemplary embodiment, the first and the second trajectory15,16each consist of a first straight portion25a,a second straight portion25band a third straight portion25c.The first straight portion25aextends away from the start point15a,16a.The third straight portion25cextends in the direction of the end point15b,16b.The second straight portion25bconnects the first straight portion25ato the third straight portion25c.The second straight portion25bforms a right angle with both the first straight portion25aand the third straight portion25c.

FIG.9is an end-side view of the end faces9of one of the pairs10according to a seventh exemplary embodiment of the active part1to which all of the embodiments relating to the first exemplary embodiment can be transferred, apart from the differences described below.

In the seventh exemplary embodiment, the first trajectory15has a start point15aand an end point15b,which is different therefrom, and intersects the line of symmetry20between the start point15aand the end point15bfour times. The first trajectory15extends in a meandering manner through all four quadrants22a-d.

The second trajectory16and the third trajectory17each have a start point16a,17aand an end point16b,17b,which is different therefrom, and run between them in a straight line. The second and the third trajectory16,17run in a straight line on different sides of the line of symmetry20. The energy intensity of the laser beam along the first trajectory15is lower than along the second and the third trajectory16,17.

According to further exemplary embodiments, the laser beam is guided along the trajectories15-17according to the first to fourth exemplary embodiment with different energy intensities.

According to further exemplary embodiments, which correspond to those described above, the line of symmetry20intersects the boundary region11centrally. The patterns which have the trajectories15-17then correspond to the patterns according toFIG.3toFIG.9rotated through 90°.

Exemplary embodiments of a method for producing the active part1according to the preceding exemplary embodiments are described below:

The method comprises a first step of providing the core2and the shaped conductors6which are inserted into the core2. In a subsequent second step, two end faces9are joined to one another in each case, so that the second end faces9form a pair10.

In a subsequent third step, a respective pair10is welded by means of a laser beam which is guided on the end faces9of the pair along the trajectories15-17according to one of the above-described exemplary embodiments. A laser device which generates the laser beam is used here. The laser device can be operated in a deactivated state, in which the laser beam is switched off or has a power which is insufficient for melting a material of the shaped conductors6. Furthermore, the laser device can be operated in an activated state, in which the laser beam can melt the material of the shaped conductor6. The energy intensity of the laser beam is variable in the activated state.

The third step of welding further comprises the following steps for a respective trajectory15-17: aligning the laser device with the start point15a-17aof the trajectory15-17in the deactivated state; and guiding the laser beam from the start point15a-17a,along the trajectory15-17, to the end point of the trajectory15b-17bin the activated state of the laser device. Here, the laser device is moved from the deactivated state to the activated state between the alignment and the guidance when the laser device is aligned with the start point15a-17aof the trajectory15-17, and is moved from the activated state to the deactivated state when the guidance has reached the end point15b-17bof the trajectory15-17. Although this has not been illustrated in the exemplary embodiments of the active part1, the closed trajectories15-17of course also have a start point and an end point, which are identical. In the case of the closed trajectory, the start point and the end point can also be different, so that the trajectory overlaps itself.

It should be noted that the active part1, which is obtained by carrying out he method, does not necessarily have to have weld seams in the form of the trajectories15-17—depending on the parameterization of the welding process.

FIG.10is a diagrammatic sketch of a vehicle100comprising an exemplary embodiment of a rotating electric machine101.

The electric machine101has a stator102and a rotor103. The stator102and/or the rotor103are/is designed as an active part1according to one of the above-described exemplary embodiments or are/is obtained by one of the above-described exemplary embodiments of the method.

The electric machine101is designed to drive the vehicle100. The vehicle100is accordingly a battery-electric vehicle (BEV) or a hybrid vehicle.