Improved method for producing skewed stators having stator windings with parallel conductor portions

Abstract

The invention specifies a method for producing a stator (11) for an electric machine (1), in which method a stator laminated core (12) having a plurality of helically extending stator slots (15), which form a skewing of the stator laminated core (12), is provided. A stator winding (14, 14a, 14b) is also provided, which comprises a plurality of straight and mutually parallel conductor portions (B, B1, B2) and a plurality of connecting portions (C), wherein at least in each case two of the parallel conductor portions (B, B1, B2) are connected to each other at a respective one of their ends by means of one of the connecting portions (C). Finally, the stator winding (14, 14a, 14b) is inserted into the stator slots (15), the stator winding (14, 14a, 14b) already having an asymmetry corresponding to the skew before being inserted into the stator slots (15). The invention also specifies an intermediate product of a stator winding (14, 14a, 14b), an electric machine (1) having a stator (11) of the kind mentioned, and also a vehicle (22) having such an electric machine (1).

Description

DESCRIPTION TITLE OF THE INVENTION: Improved method for producing skewed stators with stator windings having parallel conductor sections TECHNICAL FIELD

[0001] The invention relates to a method for producing a stator for an electrical machine, in which a stator core is provided with a plurality of stacked stator cores and a plurality of helically extending stator slots therein, which form a bevel of the stator core. Furthermore, a stator winding is provided, which comprises a plurality of straight and mutually parallel conductor sections and a plurality of connecting sections, wherein at least two of the parallel conductor sections are connected to one another at each of their ends via one of the connecting sections. Finally, the stator winding is inserted into the stator slots.Furthermore, the invention relates to an intermediate product of a stator winding, which comprises a plurality of straight and mutually parallel conductor sections and connecting sections, wherein at least two of the parallel conductor sections are connected to one another at each of their ends via one of the connecting sections. Furthermore, the invention relates to an electrical machine with a stator manufactured as described above, as well as to a vehicle with such an electrical machine. STATE OF THE ART

[0002] A method, an intermediate product, an electrical machine, and a vehicle of the aforementioned type are generally known from the prior art. The stator laminations are stacked to form a stator lamination stack, and the stator windings are then inserted into the stator slots of the stator lamination stack. The stator windings are particularly in the form of "U-pins" or "hairpins," or as "continuous wave windings."

[0003] The construction of skewed stators with such windings is particularly problematic. In such stators, the magnetic poles in the stator laminated core are arranged at an angle to achieve a smoother torque curve for the electrical machine in question. However, due to the large conductor cross-sections, these types of stator windings are comparatively rigid and difficult to bend, which is why known methods for manufacturing a stator require relatively high forces to be introduced into the stator laminated core and absorbed by it. If a fixing of the stator laminated core becomes inadvertently loose during later operation of the electrical machine, these forces can lead to undesired deformation of the stator laminated core and impair or even prevent further operation of the electrical machine. DESCRIPTION OF THE INVENTION

[0004] An object of the invention is therefore to provide an improved method for producing a stator, an improved intermediate product for a stator winding, an improved electric machine, and an improved vehicle. In particular, the introduction of forces into the stator core and thus the risk of subsequent, undesirable deformation should be avoided or at least reduced.

[0005] The object of the invention is achieved by a method of the type mentioned at the outset, in which the stator winding has an asymmetry corresponding to the skew before being introduced into the stator slots.

[0006] The object of the invention is also achieved with an intermediate product of the type mentioned above, in which the intermediate product or the stator winding, in the unassembled (and in particular in the unwound or not yet wound) state, has an asymmetry corresponding to the skew. The parallel conductor sections can be inclined, in particular, relative to a transverse extension of the stator winding.

[0007] Furthermore, the object of the invention is achieved by an electric machine with a stator manufactured using a method of the type mentioned above. The electric machine can, in particular, comprise a rotor arranged in the stator and mounted in the housing for rotation about a rotor axis, with rotor windings or rotor magnets.

[0008] Furthermore, the object of the invention is achieved by a vehicle which has an electric machine of the above-mentioned type which is intended to drive the vehicle.

[0009] The proposed measures facilitate the production of tapered stators, as no or only comparatively small forces are required to insert the stator winding into the stator slots. Accordingly, the introduction of forces into the stator core, and thus the risk of subsequent, undesirable deformation, is avoided or at least reduced.

[0010] For example, the parallel conductor sections can be inclined by a helix angle [Math 1] a = arctan(s / Z) with respect to a transverse extension of the stator winding (in the assembled state of the stator winding corresponding to a direction parallel to a rotation axis of the stator winding), wherein the parameter s specifies a gradation of the stator winding and the parameter I a length of the stator laminated core and wherein the gradation corresponds in particular to 0.5 to 2 times a circumferential distance between two adjacent stator slots.

[0011] The number of parallel conductor sections can in particular correspond to an integer multiple of the number of stator slots.

[0012] Further advantageous embodiments and developments of the invention emerge from the subclaims and from the description in conjunction with the figures.

[0013] It is advantageous if the stator winding is constructed from bow-shaped winding sections, each comprising two parallel conductor sections and a connecting section connecting them. The free ends of the parallel conductor sections are connected to each other via additional connecting sections after insertion into the stator slots. Such bow-shaped winding sections are also known as "U-pins" or "hairpins." This advantageously allows for relatively large conductor cross-sections to be realized for the stator winding.

[0014] It is also advantageous if, when preparing the stator winding, all parallel conductor sections are connected to each other via connecting sections, forming a continuous conductor. Such a stator winding is also known as a "continuous wave winding." This also advantageously allows relatively large conductor cross-sections to be realized for the stator winding, but after insertion into the stator slots, no or very few connecting sections need to be connected.

[0015] A hybrid of the last two variants is also conceivable, in which, when the stator winding is provided, more than two, but not all, of the parallel conductor sections are connected to each other via connecting sections, forming a continuous conductor. Such a stator winding corresponds, at least in part, to a "continuous wave winding" and can therefore also be referred to as a "partial continuous wave winding" or "sectional continuous wave winding."

[0016] It is advantageous if the stator winding is provided in an unwound state in which it already has an asymmetry corresponding to the skew, and is formed into a ring or spiral before being inserted into the stator slots. In this variant, only Particularly low forces are introduced into the stator laminated core, since the stator winding has almost its final shape before being inserted into the stator slots and only needs to be deformed very slightly.

[0017] It is also particularly advantageous if the stator winding is wound onto an intermediate support after being provided and formed into a ring or spiral, and if the asymmetry of the stator winding corresponding to the skew is then created. In this embodiment, the stator winding, in its unwound state, does not yet exhibit any asymmetry corresponding to the skew. This is only created on the intermediate support. For example, the intermediate support can be designed to be inherently rotatable, with the asymmetry of the stator winding corresponding to the skew being created by rotating the intermediate support. For example, the intermediate support may have upper and lower joint supports, each connected by a telescopic center rod and which can be rotated relative to each other, thus forming the skew of the stator winding. DESCRIPTION OF THE CHARACTERS

[0018] Embodiments of the invention are illustrated by way of example in the accompanying schematic figures. They show: [Fig. 1] a first example of an electrical machine shown schematically in half section; [Fig. 2] a partial longitudinal section of the stator laminated core of the electrical machine from Fig. 1; [Fig. 3] the insertion of the stator windings into the stator slots in front view; [Fig. 4] a plan view of a stator winding in the unwound state, wherein the stator winding is formed by a continuous conductor; [Fig. 5] a plan view of a stator winding in the unwound state, wherein the stator winding is formed by U-pins; [Fig. 6] an exemplary intermediate support for the stator winding in plan view; [Fig. 7] the intermediate carrier on Fig. 6 in side view; [Fig. 8] a state in which the stator winding is wound on the intermediate carrier; [Fig. 9] a state in which the skew of the stator winding was produced by twisting the intermediate support, and [Fig. 10] an exemplary vehicle with an electric machine of the proposed type. DETAILED DESCRIPTION OF THE INVENTION

[0019] By way of introduction, it should be noted that identical parts in the different embodiments are provided with the same reference symbols or component designations, possibly with different indices. The disclosure of a component contained in the description can be applied analogously to another component with the same reference symbol or component designation. Furthermore, the positional information chosen in the description, such as "top," "bottom," "rear," "front," "side," and so on, refers to the directly described and illustrated figure and, in the event of a change in position, is to be applied analogously to the new position.

[0020] Fig. 1 shows a half-section through a schematically illustrated electrical machine 1. The electrical machine 1 comprises a rotor shaft 2 and a rotor core 3 mounted thereon with several rotor cores (not shown in detail) and optional rotor windings 4 arranged therein as part of a Rotor 5. Instead of the rotor windings 4, rotor magnets (not shown), for example, could also be provided. The rotor shaft 2 is rotatably mounted about a rotor axis or stator axis A by means of (rolling) bearings 6a, 6b. Specifically, the first bearing 6a is located in a first front bearing plate 7 and the second bearing 6b in a second, rear bearing plate 8. The electric machine 1 further comprises a stator housing 9, which connects the front bearing plate 7 and the rear bearing plate 8 and together with these forms the machine housing 10 of the electric machine 1. A stator 11 or its stator laminated core 12 is fitted into the stator housing 10. The stator laminated core 12 has a plurality of axially stacked stator laminates 13 with stator windings 14 arranged therein.

[0021] Fig. 2 shows a partial longitudinal section of the stator laminated core 12 of the electrical machine 1 from Fig. 1 , wherein the sectional plane is aligned parallel to the stator axis A. In Fig. 2, several stator slots 15 can be seen, which accommodate the stator windings 14 and which are inclined by a helix angle α with respect to a longitudinal extent of the stator laminated core 12. Accordingly, the stator slots 15 run helically and form a bevel of the stator laminated core 12. In addition, a length I of the stator laminated core 12 and a circumferential distance d between two adjacent stator slots 15 are specified in Fig. 2.

[0022] Fig. 3 illustrates the insertion of the stator windings 14 into the stator slots 15 using a partial front view of the stator laminated core 12, wherein the stator windings 14 comprise a plurality of straight sections B, which are shown in detail in Figs. 4 and 5.

[0023] Fig. 4 shows a plan view of a stator winding 14a in the unwound (or not yet wound) state. The stator winding 14a comprises several straight and mutually parallel conductor sections B1, B2 and several connecting sections C, wherein the parallel conductor sections B1, B2 are each connected to one another at one of their ends via one of the connecting sections C.

[0024] A method for producing a stator 11 for an electrical machine 1 can now comprise the following steps: Providing a stator laminated core 12 with a plurality of stacked stator laminated cores 13 and a plurality of helically extending stator slots 15 therein, which form a bevel of the stator laminated core 12, Providing a stator winding 14, 14a, which comprises a plurality of straight and mutually parallel conductor sections B, B1, B2 and a plurality of connecting sections C, wherein at least two of the parallel conductor sections B, B1, B2 are connected to one another at each of their ends via one of the connecting sections C and wherein the Stator winding 14, 14a has an asymmetry corresponding to the skew before being inserted into the stator slots 15 and insertion of the stator winding 14, 14a into the stator slots 15.

[0025] The parallel conductor sections B1, B2 can in particular be inclined by a helix angle [Math 1] a = arctan(s / Z) with respect to a transverse extent q of the stator winding 14a, as is the case in Fig. 4. The transverse extent q is aligned parallel to a rotation axis of the stator winding 14a (i.e. parallel to the stator axis A) when the stator winding 14a is in the wound state. In the above formula, the parameter s specifies a gradation of the stator winding 14a and the parameter I the length of the stator laminated core 12. The gradation s can in particular correspond to 0.5 to 2 times the circumferential distance d between two adjacent stator slots 15. In addition, the number of parallel conductor sections B1, B2 can correspond to an integer multiple of the number of stator slots 15.

[0026] In Fig. 4, a variant is shown in which, when the stator winding 14a is provided, all parallel conductor sections B1, B2 are Connecting sections C are connected to each other and form a continuous conductor. This type of stator winding 14a is also referred to as a "continuous wave winding."

[0027] However, it is also conceivable that the stator winding 14b, when provided, is constructed from bow-shaped winding parts 16 ("U-pins"), each of which comprises two parallel conductor sections B, B1, B2 and a connecting section C connecting them, wherein the free ends of the parallel conductor sections B, B1, B2 are connected to one another via further connecting sections C after being introduced into the stator slots 15. This embodiment variant is shown in Fig. 5.

[0028] A hybrid of the variants shown in Figs. 4 and 5 is also conceivable. Specifically, when providing the stator winding 14, 14a, 14b, more than two, but not all, of the parallel conductor sections B, B1, B2 can be connected to one another via connecting sections C, forming a continuous conductor. The remaining free ends are in turn connected to one another via further connecting sections C after being inserted into the stator slots 15. This corresponds to a stator winding 14, 14a, 14b that is continuous at least in sections, or a "partially continuous wave winding."

[0029] 4 and 5 each represent an intermediate product of a stator winding 14, 14a, 14b, which comprises a plurality of straight and mutually parallel conductor sections B, B1, B2 and connecting sections C, wherein at least two of the parallel conductor sections B, B1, B2 are connected to one another at one of their ends via one of the connecting sections C, and wherein the intermediate product or the stator winding 14, 14a, 14b in the unassembled state (in particular in the unwound state) has an asymmetry corresponding to the slant. The parallel conductor sections B, B1, B2 are inclined with respect to a transverse extent q of the stator winding 14, 14a, 14b.

[0030] In one embodiment, the stator winding 14, 14a, 14b is provided in the unwound or not yet wound state, wherein it already has an asymmetry corresponding to the skew in this state, and is formed into a ring or a spiral before being introduced into the stator slots 15.

[0031] However, it is also conceivable that the (not yet skewed) stator winding 14 is wound on an intermediate carrier 17 after being provided and formed into a ring or a spiral and then the asymmetry of the stator winding 14 corresponding to the skewing is produced, as will be explained in more detail below with reference to Figs. 6 to 9.

[0032] 6 and 7 show an exemplary intermediate support 17, wherein Fig. 6 shows the intermediate support 17 in plan view and Fig. 7 in side view. Specifically, the exemplary intermediate support 17 comprises a base body 18 with a plurality of extensions 19 arranged thereon. The extensions 19 each comprise an upper joint support 20a and a lower joint support 20b as well as a telescopic central rod 21 connecting them. Thus, in the given example, the intermediate support 17 has an upper end section D1, a lower end section D2 and a central section E. The intermediate support 17 is designed to be rotatable. Specifically, the upper joint supports 20a can be rotated relative to the lower joint supports 20b about the longitudinal axis of the intermediate support 17, or the upper end section D1 can be rotated relative to the lower end section D2 about the longitudinal axis of the intermediate support 17.

[0033] Fig. 8 shows a state in which the stator winding 14 has been wound onto the intermediate support 17 after being provided and formed into a ring or spiral. In this state (and therefore also in the unwound or not yet wound state), the stator winding 14 does not yet exhibit any asymmetry corresponding to the skew. This is only achieved by rotating the upper joint supports 20a relative to the lower joint supports 20b or by rotating the upper End section D1 is produced relative to the lower end section D2, as illustrated in Fig. 9. Subsequently, the stator winding 14 is inserted into the stator slots 15.

[0034] Finally, Fig. 10 shows the electric machine 1 installed in a vehicle 22. The vehicle 22 has two axles, one of which is driven. Specifically, the electric machine 1 is connected to the half-axles 24 of the rear axle or front axle via an optional transmission 23. The driven wheels 25 are mounted on the half-axles 24. The electric machine 1, the transmission 23 and the half-axles 24 are part of the drive train of the vehicle 22. The vehicle 22 is driven at least partially or temporarily by the electric machine 1. This means that the electric machine 1 can serve to drive the vehicle 22 alone or, for example, can be provided in conjunction with an internal combustion engine (hybrid drive).

[0035] Finally, it is noted that the scope of protection is determined by the patent claims. However, the description and drawings must be used to interpret the claims. The features contained in the figures can be interchanged and combined with one another as desired. In particular, it is also noted that the devices depicted may in reality comprise more or fewer components than shown. In some cases, the depicted devices or their components may also be shown not to scale and / or enlarged and / or reduced in size. List of reference symbols 1 electric machine 2 rotor shaft 3 rotor lamination pack 4 rotor winding 5 Rotor 6a, 6b (rolling) bearings 7 front bearing shield 8 rear bearing plate 9 Stator housing 10 machine housings 11 Stator 12 stator lamination pack 13 Stator sheet 14, 14a, 14b Stator winding 15 Stator slot 16 bow-shaped winding part (U-pin) 17 intermediate carriers 18 base bodies 19 Extension 20a, 20b joint support 21 center bar 22 vehicles 23 gearboxes 24 semi-axle 25 wheels cx Helix angle d Circumferential distance stator slot I Stator length q Transverse extension of stator winding s Stepping A Stator axis B, B1 , B2 straight section stator winding C Connecting section stator winding D1 , D2 end section intermediate support E Middle section intermediate support

Claims

Claims [Revendication 1] Method for producing a stator (11) for an electrical machine (1), comprising the steps - Providing a stator laminated core (12) with a plurality of stacked stator laminated cores (13) and a plurality of helically extending stator slots (15) therein, which form a bevel of the stator laminated core (12), - Providing a stator winding (14, 14a, 14b) which comprises a plurality of straight and mutually parallel conductor sections (B, B1, B2) and a plurality of connecting sections (C), wherein at least two of the parallel conductor sections (B, B1, B2) are connected to one another at one of their ends via one of the connecting sections (C), and wherein the stator winding (14, 14a, 14b) has an asymmetry corresponding to the skew before being introduced into the stator slots (15), and - Inserting the stator winding (14, 14a, 14b) into the stator slots (15). [Revendication 2] Method according to claim 1, characterized in that the parallel conductor sections (B, B1, B2) are inclined by a helix angle [Math. 1] a = arctan(s / Z) with respect to a transverse extension (q) of the stator winding (14, 14a, 14b), wherein (s) indicates a gradation of the stator winding (14, 14a, 14b) and (I) a length of the stator laminated core (12), and wherein the gradation (s) corresponds to 0.5 to 2 times a circumferential distance (d) between two adjacent stator slots (15). [Revendication 3] Method according to claim 1 or 2, characterized in that the number of parallel conductor sections (B, B1, B2) corresponds to an integer multiple of the number of stator slots (15). [Revendication 4] Method according to one of claims 1 to 3, characterized in that the stator winding (14, 14a, 14b) is constructed during provision from respective bow-shaped winding parts (16), which each comprise two parallel conductor sections (B, B1, B2) and a connecting section (C) connecting them, wherein the free ends of the parallel Conductor sections (B, B1, B2) are connected to one another via further connecting sections (C) after being inserted into the stator slots (15). [Revendication 5] Method according to one of claims 1 to 3, characterized in that when providing the stator winding (14, 14a, 14b) more than two of the parallel conductor sections (B, B1, B2) are connected to one another via connecting sections (C) and form a continuous conductor. [Revendication 6] Method according to claim 5, characterized in that when providing the stator winding (14, 14a, 14b) all parallel conductor sections (B, B1, B2) are connected to one another via connecting sections (C) and form a continuous conductor. [Revendication 7] Method according to one of claims 1 to 6, characterized in that the stator winding (14, 14a, 14b) is provided in a developed state in which it already has an asymmetry corresponding to the skew, and is formed into a ring or a spiral before being introduced into the stator slots (15). [Revendication 8] Method according to one of claims 1 to 6, characterized in that the stator winding (14, 14a, 14b) is wound on an intermediate carrier (17) after being provided and is formed into a ring or a spiral, and then the asymmetry of the stator winding (14, 14a, 14b) corresponding to the skew is produced. [Revendication 9] Method according to claim 8, characterized in that the intermediate carrier (17) is designed to be rotatable and the asymmetry of the stator winding (14, 14a, 14b) corresponding to the skew is produced by rotating the intermediate carrier (17). [Revendication 10] Intermediate product of a stator winding (14, 14a, 14b), which comprises a plurality of straight and mutually parallel conductor sections (B, B1, B2) and connecting sections (C), wherein at least two of the parallel conductor sections (B, B1, B2) are connected to one another at one of their ends via one of the connecting sections (C), characterized in that - the intermediate product or the stator winding (14, 14a, 14b) in the unassembled state has an asymmetry corresponding to the skew. [Revendication 11] Intermediate product according to claim 10, characterized in that the parallel Conductor sections (B, B1, B2) are inclined relative to a transverse extension (q) of the stator winding (14, 14a, 14b). [Revendication 12] Electrical machine (1 ), characterized by a stator (11 ) which is produced by a method according to one of claims 1 to 9, and a rotor (5) rotatably arranged therein. [Revendication 13] Vehicle (22) with an electric machine (1) according to claim 12, which is provided for driving the vehicle (22).

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