Method for producing a wound stator

Abstract

The invention relates to a method for producing a wound stator (1) for an electric machine, comprising the following steps: providing a hollow-cylindrical stator having a multiplicity of stator slots (3) that extend radially outwardly from an inner shell surface (4) of the stator (1) and through the stator (1) in the axial direction; providing a wave winding (5); providing a puller mandrel (6); rolling the wave winding (5) onto the puller mandrel (6); axially pushing the puller mandrel (6) into the hollow-cylindrical stator (1); actuating pulling bars (7) arranged on the puller mandrel (6) in the radial direction, such that the pulling bars (7) push the wave winding (5) into the stator slots (3), wherein, when the wave winding (5) is pushed into the stator slots (3), in the region of a winding head (8) of the wave winding (5), the pulling bars (7) are set back radially inwardly in relation to the pulling bars (7) in the region of the stator slots (3).

Description

[0001] Method for producing a wound stator

[0002] The present invention relates to a method for producing a wound stator for an electrical machine, comprising the following steps: providing a hollow cylindrical stator having a plurality of stator slots extending radially outward from an inner circumferential surface of the stator and in the axial direction through the stator; providing a wave winding;

[0003] Provision of a drawing-in mandrel; rolling the wave winding onto the drawing-in mandrel; axial insertion of the drawing-in mandrel into the hollow cylindrical stator; actuation of drawing-in lamellas arranged on the drawing-in mandrel in the radial direction so that the drawing-in lamellas push the wave winding into the stator slots.

[0004] Electric motors are increasingly being used to power motor vehicles, creating alternatives to combustion engines that require fossil fuels. Considerable efforts have already been made to improve the everyday suitability of electric drives and also to provide users with the same level of driving comfort they are accustomed to.

[0005] A detailed description of an electric drive can be found in an article in the magazine ATZ, Volume 63, May 2020, pages 360-365, by Erik Schneider, Frank Fickl, Bernd Cebulski, and Jens Liebold, titled "Highly Integrated and Flexible Electric Drive Unit for E-Vehicles." This article describes a drive unit for a vehicle axle that includes an electric motor arranged concentrically with a bevel gear differential. Such drive units are also referred to as e-axles.

[0006] For the development of electrical machines, in particular electrical machines for the above-mentioned fully electric motor vehicles or for wheel hub drives, basically different winding technologies for a stator of an electrical machine are known.

[0007] Electrical machines with a hollow cylindrical stator, i.e., internal rotor machines, and configured for use as traction drives in motor vehicles often have a stator winding with a rectangular cross-section to achieve high power density. In electrical machines intended for motor vehicle propulsion, the stator windings are therefore typically designed as wave windings.

[0008] The construction of a stator with a wave winding is a stator design in which winding mats are used to form the phase-specific windings. To form the distributed windings, the individual winding wires or partial mats are interwoven, for example, using a winding or layering process, and inserted into the stator slots.

[0009] The process of pulling such a wave winding into the stator is well known and is described, for example, in WQ2017093477A1. The process, which is currently known from the state of the art, is divided into two production stages. In a first step, the wave winding, which has been rolled onto the pulling mandrel, is joined radially into the stator's laminated core. By joining radially outwards, the winding wires of the wave winding are moved from the slot area (slot opening) to the slot base. The winding overhang is not yet in its final position at this point. The pulling mandrel and its pulling laminations are then moved back to their home position. In the second step, the winding overhang is reshaped to its radial dimension by inserting additional pulling laminations onto the pulling mandrel.The current state of the art involves inserting the wave winding and reshaping the winding head to the same radial position in all sections / slots of the stator. However, during production, high forces can occur during the insertion of a wave winding into the stator, causing tension in the wire ends or the winding head of the wave winding mat, which can subsequently lead to unintentional damage to the insulation layer of the winding conductors.

[0010] It is therefore the object of the invention to avoid or at least mitigate these disadvantages known from the prior art and to provide a correspondingly improved method for producing a wound stator for an electrical machine.

[0011] This object is achieved by a method for producing a wound stator for an electrical machine, comprising the following steps:

[0012] • Providing a hollow cylindrical stator having a plurality of stator slots extending radially outward from an inner surface of the stator and in the axial direction through the stator,

[0013] • Provision of a wave winding,

[0014] • Provision of a pulling mandrel,

[0015] • Rolling the wave winding onto the mandrel

[0016] • Axial insertion of the mandrel into the hollow cylindrical stator

[0017] • Actuation of pull-in lamellae arranged on the pull-in mandrel in the radial direction, so that the pull-in lamellae push the wave winding into the stator slots, wherein when the wave winding is pushed into the stator slots in the area of ​​a winding head of the wave winding, the pull-in lamellae are set back radially inwards compared to the pull-in lamellae in the area of ​​the stator slots.

[0018] This prevents the otherwise possible occurrence of warping, particularly at the wire starts of the winding overhang, which are oriented radially inwards towards the pull-in laminations of the pulling mandrel and which can become warped during uniform radial forming of the winding overhang. To this end, the pull-in laminations are radially offset in the area of ​​the winding overhang and preferably also specifically in the area of ​​the wire ends. As a result, when the wire package of the wave winding is joined into the stator, no clamping effect occurs between the winding overhang and the corresponding pull-in lamination(s) that fixes the winding overhang and in particular the wire ends. The joining force is thus introduced exclusively via axially and / or radially adjacent pull-in laminations, where no clamping effect occurs, or the joining force is introduced in the axial area in the stator at the wire starts.Since after the expansion process, i.e. the radial insertion of the wave winding into the stator slots, the wire ends or the winding head of the wave winding are located radially further inward than the conductor sections of the wave winding already inserted into the stator slots, this offset is now compensated in the second process step - the winding head expansion.

[0019] The stator to be manufactured preferably has a stator body. The stator body can be made in one piece or in multiple pieces, in particular segmented. A one-piece stator body is characterized in that the entire stator body is made in one piece over its entire circumference. The stator body is generally formed from a large number of stacked laminated electrical sheets, each of the electrical sheets being formed to form a closed circular ring. A segmented stator body is characterized in that it is made up of individual stator segment parts. The stator body can be made up of individual stator teeth or groups of stator teeth, each individual stator tooth or group of stator teeth being formed from a large number of stacked laminated electrical sheets, each of the electrical sheets being formed as a stator segment sheet part.

[0020] The stator body is preferably formed from one or more stator lamination stacks. A stator lamination stack is understood to be a plurality of laminated individual laminations or stator laminations, usually made of electrical steel, which are stacked and stacked together to form a so-called stator lamination stack. The individual laminations can then be held together in the lamination stack, for example, by gluing, welding, or screwing.

[0021] The stator teeth of the stator are preferably formed in the stator body. Stator teeth are components of the stator body that are circumferentially spaced, tooth-like, radially inwardly directed parts of the stator body, with an air gap for the magnetic field formed between their free ends and a rotor body. The air gap is the gap existing between the rotor and the stator. In a radial flux machine, this is a substantially circular gap with a radial width that corresponds to the distance between the rotor body and the stator body.

[0022] The stator is particularly intended for use in an electric machine within a drive train of a motor vehicle. The electric machine is particularly intended for use within a drive train of a hybrid or fully electric motor vehicle. In particular, the electric machine is dimensioned such that vehicle speeds of greater than 50 km / h, preferably greater than 80 km / h and in particular greater than 100 km / h can be achieved. The electric machine particularly preferably has an output of greater than 30 kW, preferably greater than 50 kW and in particular greater than 70 kW. It is further preferred that the electric machine provides rotational speeds of greater than 5,000 rpm, particularly preferably greater than 10,000 rpm, very particularly preferably greater than 12,500 rpm.

[0023] According to an advantageous embodiment of the invention, it can be provided that the majority, preferably all, of the electrical conductors of the wave winding have a substantially rectangular cross-section. The advantage of this embodiment is that generally standard electrical conductors can be used to form the stator winding, which is particularly advantageous in terms of stator manufacturing costs. Furthermore, a high degree of filling of the stator slots can be achieved.

[0024] According to a further preferred development of the invention, it can also be provided that after the wave winding has been inserted into the stator slots in the region of the winding overhang, the pull-in laminations are displaced radially outwards. Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the pull-in laminations in the region of the winding overhang are displaced radially outwards in such a way that they act on the inner circumference of the winding overhang with a radially outward-acting force. The advantageous effect of this embodiment is that the winding overhang is reshaped after the conductor sections of the wave winding have been inserted into the stator slots. This therefore results in a temporal decoupling of the insertion of the wave winding into the stator slots and the forming of the winding overhang, which reduces the risk of undesired tension in the winding overhang area during the stator manufacturing process.

[0025] According to another particularly preferred embodiment of the invention, it can be provided that, before the radially inwardly directed repositioning of the pull-in laminations, they are offset to a substantially identical outer diameter. This can achieve, in particular, the effect that both the winding overhang and the conductor sections of the wave winding extending in the stator slots are joined to the same radial dimension.

[0026] Furthermore, the invention can also be further developed in such a way that the intake slats are designed to be essentially identical, which, due to the increased uniformity, realizes cost advantages in their production but also advantages in terms of process control.

[0027] In a likewise preferred embodiment of the invention, it can also be provided that the winding head has wire ends via which the wave winding can be electrically contacted and energized. In this context, it can also be advantageous to further develop the invention such that, when the wave winding is inserted into the stator slots, the pull-in laminations in the region of the wire ends of the winding head are set back radially inward relative to the pull-in laminations in the region of the stator slots. The advantage that can be realized in this way is that a process adjustment is only necessary in the region or regions of the winding head in which the risk of distortion of the winding conductors is particularly high.

[0028] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept. It shows:

[0029] Figure 1 shows a stator in a first manufacturing state in an axial section,

[0030] Figure 2 shows a stator in a first manufacturing state in a cross-sectional view of the slot area,

[0031] Figure 3 shows a stator in a first manufacturing state in a cross-sectional view of the winding head area,

[0032] Figure 4 shows a stator in a second manufacturing state in an axial section,

[0033] Figure 5 shows a stator in a second manufacturing state in a cross-sectional view of the slot area,

[0034] Figure 6 shows a stator in a second manufacturing state in a cross-sectional view of the winding head area,

[0035] Figure 7 shows a stator in a third manufacturing state in an axial section,

[0036] Figure 8 shows a stator in a third manufacturing state in a cross-sectional view of the slot area,

[0037] Figure 9 shows a stator in a third manufacturing state in a cross-sectional view of the winding head area,

[0038] Figure 10 shows a stator in a fourth manufacturing state, in a cross-sectional view of the winding head area. A method for producing a wound stator 1 for an electrical machine is explained in more detail using Figures 1-10 as an example.

[0039] First, a hollow cylindrical stator 1 is provided with a plurality of stator slots 3, which extend from an inner circumferential surface 4 of the stator 1 radially outwards and in the axial direction through the stator 1, which can be clearly seen, for example, in Figure 2.

[0040] A wave winding 5 and a pull-in mandrel 6 are then prepared, and the wave winding 5 is wound onto the pull-in mandrel 6. The wave winding 5 is formed from winding conductors with a rectangular cross-section. The pull-in mandrel 6, thus equipped with the wave winding 5, is then inserted axially into the hollow cylindrical stator 1. This manufacturing stage is shown in Figures 1-3.

[0041] Next, the actuation of the pull-in lamellae 7 arranged on the pull-in mandrel 6 takes place in the radial direction, so that the pull-in lamellae 7 push the wave winding 5 into the stator slots 3, which can be seen in Figures 4-6.

[0042] It can be clearly seen from the combination of Figures 1-3 and Figures 4-6 that when the wave winding 5 is inserted into the stator slots 3 in the area of ​​a winding head 8 of the wave winding 5, the pull-in laminations 7 are set back radially inwards compared to the pull-in laminations 7 in the area of ​​the stator slots 3.

[0043] As can be seen in Figures 7-9, after the wave winding 5 has been inserted into the stator slots 3, the pull-in laminations 7 are displaced radially outward in the region of the winding overhang 8. The pull-in laminations 7 are thereby displaced radially outward in the region of the winding overhang 8 in such a way that they act with a radially outward force on the inner circumference of the winding overhang 8. This ensures that the pull-in laminations 7 are displaced to a substantially identical outer diameter before being radially inwardly repositioned.

[0044] The winding overhang 8 can have wire ends via which the wave winding 5 can be electrically contacted and energized. When the wave winding 5 is inserted into the stator slots 3, only the pull-in laminations 7 in the region of the wire ends of the winding overhang 8 can be set back radially inwards compared to the pull-in laminations 7 in the region of the stator slots 3, as shown in Figure 10. Thus, firstly the regions of the winding overhang 8 that lie outside the region of the wire ends are radially formed in the circumferential direction. The wire ends can then be radially formed, resulting in the manufacturing state shown in Figure 9. In the exemplary embodiment shown in Figure 10, the wire ends are circumferentially adjacent at approximately 11 o'clock, 12 o'clock, and 1 o'clock.

[0045] The invention is not limited to the embodiments illustrated in the figures. The above description is therefore not to be considered restrictive, but rather explanatory. The following claims are to be understood in such a way that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Where the claims and the above description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing a priority.

[0046] List of reference symbols

[0047] 1 stator 3 stator slots

[0048] 4 Shell surface

[0049] 5 wave winding

[0050] 6 retracting mandrel

[0051] 7 Feed lamellas 8 Winding head

Claims

Claims 1. A method for producing a wound stator (1) for an electrical machine, comprising the following steps: • Providing a hollow cylindrical stator with a plurality of stator slots (3) extending radially outwards from an inner surface (4) of the stator (1) and in the axial direction through the stator (1), • Provision of a wave winding (5), • Provision of a pulling mandrel (6), • Rolling the wave winding (5) onto the insertion mandrel (6) • Axial insertion of the insertion mandrel (6) into the hollow cylindrical stator (1) • Actuation of pull-in lamellae (7) arranged on the pull-in mandrel (6) in the radial direction, so that the pull-in lamellae (7) push the wave winding (5) into the stator slots (3), characterized in that when the wave winding (5) is pushed into the stator slots (3) in the region of a winding head (8) of the wave winding (5), the pull-in lamellae (7) are set back radially inwards relative to the pull-in lamellae (7) in the region of the stator slots (3).

2. Method according to claim 1, characterized in that the wave winding (5) is formed from winding conductors with a rectangular cross-section. Method according to claim 1 or 2, characterized in that after the wave winding (5) has been pushed into the stator slots (3) in the region of the winding overhang (8), the pull-in laminations (7) are displaced radially outwards. Method according to claim 3, characterized in that the pull-in laminations (7) are displaced radially outwards in the region of the winding overhang (8) in such a way that they act on the inner circumference of the winding overhang (8) with a radially outward-acting force. Method according to one of the preceding claims, characterized in that before the radially inward-directed repositioning of the pull-in laminations (7), these were displaced to a substantially identical outer diameter. Method according to one of the preceding claims, characterized in that the pull-in laminations (7) are designed to be substantially identical.Method according to one of the preceding claims, characterized in that the winding head (8) has wire ends via which the wave winding (5) can be electrically contacted and energized. Method according to claim 7, characterized in that when the wave winding (5) is inserted into the stator slots (3), the pull-in lamellae (7) are set back radially inward relative to the pull-in lamellae (7) in the region of the stator slots (3) in the region of the wire ends of the winding head (8).

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