WO2024088466A1

WO2024088466A1 - Method for producing a stator for an electric machine; stator for an electric machine; and forming tool

Info

Publication number: WO2024088466A1
Application number: PCT/DE2023/100730
Authority: WO
Inventors: Markus Urbaschek
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2022-10-26
Filing date: 2023-09-29
Publication date: 2024-05-02
Also published as: DE102023126681A1

Abstract

The invention relates to a method for producing a stator (1) for an electric machine, wherein in a first step a coil carrier (2) with regularly spaced teeth (3) is provided, and then in a second step a plurality of partial coils (4) are wound onto the teeth (3), wherein the partial coils (4) are connected to one another in groups towards an end face (5) of the stator (1) by means of connecting wires (6), wherein in a third step at least one connecting wire (6) is plastically deformed locally, forming an axially inwardly projecting loop region (7a), wherein at the same time the connecting wire (6) is tensioned in the circumferential direction of the stator. The invention also relates to a forming tool (8) and a stator (1).

Description

Method for producing a stator for an electrical machine; stator for an electrical machine; and forming tool

The invention relates to a method for producing a stator for an electrical machine, wherein the electrical machine is designed, for example, as a brushless DC motor, and wherein in a first step a coil carrier with regularly spaced teeth is provided and then in a second step several partial coils are wound onto the teeth, wherein the partial coils are connected to one another in groups by means of connecting wires towards an end face (i.e. axial side) of the stator. The invention further relates to a stator produced by means of the method, as well as a forming tool.

The prior art in this field is already well known. For example, WO 2020/057898 A1, DE 10 2015211 836 A1 and DE 102018 222 891 A1 disclose various winding processes for producing a stator.

When manufacturing electrical machines of this type, there is an increasing requirement to make the stator as compact as possible in order to be able to use it in a variety of smaller installation spaces. In the designs already known from the state of the art, it has also been shown that the existing mounting devices for the stator windings are often relatively complex, requiring a relatively high number of additional components.

It is therefore an object of the present invention to provide a wound stator which is compact in terms of its installation space and which has a lower complexity.

This is achieved according to the invention in that in a third step at least one connecting wire is plastically deformed locally to form a loop area which is axially inwardly flared, wherein at the same time the at least one Connecting wire is stretched in the circumferential direction of the stator. A loop area that is flared axially inwards is to be understood in particular as a loop area that is flared in the axial direction (ie along an axis of rotation of a rotor that is arranged to rotate relative to the stator) predominantly (possibly with a radial extension component) or exclusively (without a radial extension component) and extends in the direction of the stator body. In other words, the direction indication axially inwards is to be understood as meaning that the loop has an open, possibly narrowed area, from which the connecting wire extends from the two boundaries of the opening in

Circumferential direction extends in an axial direction, the axial direction being defined in relation to the front side of the stator such that a first axial direction points away from the front side from the stator and is defined as axially outward, while the opposite direction points from the front face to the teeth, i.e. to the stator body, and is thus defined as axially inward. The closed side of the loop is thus spaced axially inward from the open area of the loop. Additional axial space is not necessary due to this loop area extending axially inward.

This makes it possible to manufacture a compact stator coil as easily as possible.

Further advantageous embodiments are claimed in the subclaims and explained in more detail below.

It is therefore also advantageous if the connecting wire with its loop areas is accommodated in at least one axially open and circumferentially encircling receiving groove/cooling of the stator carrier. This results in the stator being constructed as simply as possible.

Furthermore, it is advantageous if several loop areas are formed distributed in the circumferential direction on one connecting wire and/or distributed on several connecting wires. This allows the tension of the connecting wires to be individually adjusted in the simplest possible way. If there is at least one first loop region which is flared in a first axial direction and at least one second loop region which is flared in a second axial direction opposite to the first axial direction, the loop regions are variably adjustable and can be integrated into existing installation spaces.

It can be particularly advantageous if both the first and the second loop region are each located axially within a winding space of the stator, the winding space being axially delimited by the axially outermost tangential regions of the partial coils and connecting wires. In other words, the winding space is defined by the windings of the partial coils and connecting wires, which is present without loop regions. This means that the tangential windings, i.e. the windings in the circumferential direction, are present in this region, and there can be sections in the axial and/or radial direction between the individual tangential sections. However, there is an axially outer layer of windings that represent an axial edge region of the winding space. Viewed from this edge region or axial boundary of the winding space, all windings, in the case described also the loop regions, lie exclusively in the axially inward direction. Excepted from this may be connection areas of windings or connecting wires that connect the windings or connecting wires to connecting elements for connecting the stator to electrical circuits. Such connection areas are expressly excluded from the loop areas according to the invention or do not contribute to the winding space.

It has also proven to be advantageous if the at least one loop area/each of the several loop areas is produced by means of a manual pressing/pressing process. This enables the pre-tension of the connecting wire to be individually adjusted.

It is therefore also expedient if the at least one loop area / each of the several loop areas is formed by means of a mechanical forming tool is formed. The forming tool is designed, for example, as a pair of pliers. This ensures efficient production of the stator. As an alternative to the preferably exclusively mechanical formation of the at least one loop area by means of a forming tool, it is also expedient if the at least one loop area is introduced automatically, for example by means of a robot (using the forming tool).

To ensure that the electrical machine is manufactured as efficiently as possible, it is also advantageous if the coil carrier is held in a holding device as a linear (i.e. unrolled) structure in the second step. This means that the coil carrier is initially arranged in one plane in order to wind up the corresponding partial coils. This makes the winding process much easier.

It is therefore again advantageous if the coil carrier is formed into a ring-shaped structure after the second step and before the third step. This allows at least one loop area to be skilfully introduced while generating sufficient tension.

The invention further relates to a forming tool for forming a loop region on a stator coil, with two forming jaws that can be moved relative to one another in a predetermined direction of deformation, wherein two pin-shaped first projections that are spaced apart from one another and each run transversely to the direction of deformation are arranged on a first forming jaw, and a pin-shaped second projection that also runs transversely to the direction of deformation is arranged on a second forming jaw, wherein the forming jaws are designed in such a way that the second projection can be pushed in and out of a space between the two first projections. However, it is not necessary for the forming jaws to move parallel to one another. Simpler or more complex relative movements between the forming jaws are also conceivable. With regard to the forming tool, it is also expedient if the projections run parallel to one another and/or perpendicular to the deformation direction. This results in a forming tool that is as easy to manufacture as possible.

For reproducible deformation, it is further advantageous if the first forming jaw has a guide groove between the first projections, into which guide groove a guide projection formed complementarily to it can be inserted. The guide projection further preferably extends to the guide groove in such a way that the guide projection and guide groove are in sliding contact with one another when the forming jaws are in a certain (second) position relative to one another.

If the forming jaws directly form the jaws of a pair of pliers, the forming tool can be manufactured as simply as possible.

Particularly preferably, the forming tool is intended for use in a method as described above.

The invention also relates to a stator according to claim 7.

The loop area, which is flared axially inwards according to the invention, allows axial and radial installation space to be saved.

In addition, loop areas that extend axially outwards can also be provided. This allows a variable design of the loop area depending on the space available.

In a further development, it can be provided that the stator has a winding space that is limited in the axial direction by the partial coils and the connecting wires, wherein the axial boundary of the winding space is defined by the tangentially running areas of the partial coils and connecting wires that are located axially furthest outward in relation to the stator. Possible axially running connection areas contribute nothing to this winding space. The intended loop areas will then be formed axially within the winding space and will not exceed its axial limit.

This means that an axial extension of the front surface of the stator is not possible due to the loop areas, regardless of the axial direction in which they extend.

In a further development, it is then envisaged that the stator is manufactured according to the method according to one of the previously explained embodiments.

In other words, according to the invention, at least one axial loop (loop region), more preferably several axial loops, is formed on the interconnection wires of a linearly wound electric motor (electric machine). The protruding wires are bent in the axial direction, possibly in opposite directions (depending on the pole), in particular by means of pins (pin-shaped projections), so that loops (loop regions) are formed.

These axial loops are located around the circumference of the motor and reduce the radial space requirement.

The invention will now be explained in more detail with reference to figures.

Show it:

Fig. 1 is a perspective view of a peripheral region of a stator for an electrical machine produced according to the invention according to a first embodiment, wherein two (first) loop regions formed on a connecting wire can be clearly seen,

Fig. 2 is a perspective view of a further circumferential region of the stator according to Fig. 1, wherein a second loop region can be seen which extends opposite to the first loop regions.

Fig. 3 is a plan view of a holding device used to manufacture the stator according to the invention, wherein several partial coils are already wound on a linearly arranged coil carrier, Fig. 4 is a plan view of a stator according to the invention in an intermediate stage of production, wherein the connecting wires have not yet been plastically deformed to form the loop regions, but the various locations at which the loop regions are to be introduced have already been marked,

Fig. 5 is a plan view of a forming tool used to form a loop area with a connecting wire already inserted, the forming tool being in a first position in which the connecting wire is not yet plastically deformed,

Fig. 6 is a plan view of the forming tool of Fig. 5, wherein the forming tool is in a second position in which two forming jaws of the forming tool are pushed into each other and thus the connecting wire is plastically deformed to form a loop region,

Fig. 7 is a perspective view of a forming tool according to the invention in the region of its forming jaws,

Fig. 8 is a plan view of a forming tool according to the invention, whereby its design as a pair of pliers can be clearly seen, and

Fig. 9 is a flow chart illustrating a manufacturing method according to the invention.

The figures are merely schematic in nature and serve solely to facilitate an understanding of the invention. The same elements are provided with the same reference numerals.

A stator 1 produced according to the invention is illustrated in connection with Figs. 1, 2 and 4. The stator 1 is part of an electrical machine (also referred to as an electric motor) which is not shown in more detail for the sake of clarity. The electrical machine is preferably designed as a brushless DC motor. formed. In addition to the ring-shaped stator 1, the electric machine has a rotor arranged radially (radial is a direction perpendicular to a rotation axis of the rotor) within the stator 1 in the usual way. The rotor can in turn be connected or is already connected in the usual way to an output shaft protruding axially (axial is a direction along/parallel to the rotation axis of the rotor) from the stator 1 in order to drive other components during operation, preferably in a drive train of a motor vehicle.

The manufacture of the stator 1 according to the invention can be seen in general in Fig. 9 and in more detail in connection with Figs. 1 to 6. For the manufacture of the stator

1, a coil carrier 2 is first provided according to Fig. 3 (in a first step a)). The coil carrier 2 is initially linear, i.e. unwound. The coil carrier 2 is received on a holding device 9 according to Fig. 3 for winding up a coil arrangement/stator coil.

Following this (in a second step b)), the coil arrangement is wound onto the coil carrier 2 in the form of several partial coils 4. The coil carrier 2 has several teeth 3 which are arranged next to one another at regular intervals along its linear structure 10 in Fig. 3. A partial coil 4 is wound onto each tooth 3, whereby the partial coils 4 merge into one another/are connected to one another in groups, depending on the circuit of the stator, and form a higher-level stator coil.

Fig. 3 also clearly shows that after winding the coil carrier

2 several connecting wires 6 (copper wires), which serve to connect the partial coils 4 assigned to a group, protrude to a later end face 5 / axial side of the stator 1 and run at least partially along the (here linear) extension of the coil carrier 2.

After the winding process of the partial coils 4 as shown in Fig. 3, the coil carrier is brought into its ring-shaped structure 11 intended for use in the electrical machine as shown in Fig. 4. As a result, the Connecting wires in a circumferential direction of the stator 1 and are positioned accordingly.

Subsequently, in a third step c) of the method according to the invention, the connecting wires 6, which connect the partial coils 4 to one another in groups, are locally plastically deformed, whereby they automatically prestress themselves in the circumferential direction.

Several loop regions 7a, 7b that are deliberately introduced by this plastic deformation can be clearly seen in Figs. 1 and 2. In Fig. 1, two first loop regions 7a are shown on a single connecting wire 6. These two loop regions 7a extend in a first axial direction of the stator 1 and lie radially from the outside directly against the coil carrier 2. It should be emphasized that the axial extent of the loop regions 7a lies within a winding space 21, i.e. no additional axial installation space is taken up by the loop regions 7a. The winding space 21 is limited to the outside in the axial direction by the tangential regions of the partial coils 4 and the connecting wires 6.

A second loop region 7b is shown in Fig. 2, which extends in a second axial direction opposite to the first axial direction. The second loop region 7b is arranged on a further connecting wire 6 and also lies radially from the outside on the coil carrier 2. Here too, the second loop region 7b always lies axially within the winding space 21.

In this way, the loop areas 7a, 7b are formed on the respective connecting wires at the points D1, D2 and D3 of the stator shown in Fig. 4. This results in a radial pre-tensioning and a displacement of the other connecting wires 6 or their sections in the radial direction inwards. This results in the connecting wires 6 being fully in contact with the coil carrier 2 in the radial direction from the outside. In Figs. 5 and 6, a deformation process of the connecting wires 6, i.e. for forming the loop areas 7a, 7b, is schematically illustrated. The forming process takes place by means of a forming tool 8, which is shown in more detail below in Figs. 7 and 8.

According to Fig. 5, the forming tool 8 is first placed in a first position on the connecting wire 6, so that the connecting wire 6 is located between, on the one hand, two first projections 14 of a first forming jaw 12 of the forming tool 8 and, on the other hand, a second projection 15 of a second forming jaw 13 of the forming tool 8. For plastic deformation, the forming tool 8 (i.e. the forming jaws 12, 13 relative to each other) is brought into a second position. The forming jaws 12, 13 are moved/pressed towards each other from the first position to the second position in such a way that a loop region 7a, 7b is formed.

It can be seen that the two pin-shaped first projections 14 of the first forming jaw 12, which run parallel to one another, are spaced apart from one another in such a way that the pin-shaped second projection 15 of the second forming jaw 13, which runs parallel to the first projections 14, can be moved/pushed into a gap 16 between the two first projections 14, with the connecting wire 6 in between. The distance between the facing sides of the projections 14, 15 is thus equal to or greater than the sum of the dimensions of the diameter of the second projection 15 and twice the diameter of the connecting wire 6.

Thus, the forming tool 8 can be moved between a first position shown in Fig. 5 and a second position shown in Fig. 6.

The forming tool 8 is illustrated in more detail in an exemplary embodiment in Figs. 7 and 8. The forming tool 8 is designed as a pliers tool / pliers 19 and is equipped directly with the forming jaws 12, 13 on its jaws. The forming jaws 12, 13 are thus preferably moved in the process exclusively in a deformation direction 20 from the first Position into the second position and back again. The first and second projections 14, 15 protrude perpendicular to this deformation direction 20 and to a common side of the forming jaws 12, 13.

It can also be seen that in the first forming jaw 12 between the first projections 14, i.e. in the intermediate space 16, a guide groove 17 in the form of a groove is also introduced, which also runs parallel to the first projections 14. A guide projection 18 complementary to this guide groove 17 is formed on the second forming jaw 13. If the forming tool 8 is closed, i.e. moved from the first position according to Fig. 5 to the second position according to Fig. 6, the guide projection 18 is pushed into the guide groove 17, implementing a sliding guide between the forming jaws 12, 13. The second projection 15 is preferably formed directly on the front side of the guide projection 18.

For the sake of completeness, it should be noted that the forming tool 8 in further preferred embodiments, which are not shown here for the sake of brevity, is part of an automatic system, i.e. a robot that introduces the loop areas 7a, 7b fully automatically. However, the forming tool 8 also functions according to the principle explained above and is largely constructed in the same way.

In other words, according to the invention, the interconnection wires (connection wires 6) are formed into axially or diagonally running loops (loop areas 7a, 7b) using a suitable tool (forming tool 8). In this way, the available installation space can be used cleverly. The loops have the advantage that their plastic deformation puts tension on the interconnection wire and therefore the springback is less. This makes the installation space required even smaller.

A manual tool (forming tool 8) can be used to apply the procedure. However, a fully automatic machine/system with a forming tool 8 based on the same principle is preferably used. The tool is used to deform the interconnection wires, which consists, for example, of several bolts/pins (protrusions 14, 15) that can be moved relative to one another. One jaw of the tool preferably contains two pins, and an opposite jaw contains a single pin, with the single pin being positioned centrally between the other two. By opening and closing the pliers, the pins move relative to one another. A wire/interconnection wire clamped between them is thereby specifically bent into the U-shaped loop.

The same principle can also be used as a forming tool 8 of a fully automatic machine, but here the movement is preferably realized by compressed air cylinders and corresponding joints / guides and the sequence of forming is specified by the control of the assembly system.

List of reference symbols

Stator

Coil carrier tooth partial coil front side connecting wire a first loop area b second loop area forming tool holding device 0 linear structure 1 ring-shaped structure 2 first forming jaw 3 second forming jaw 4 first projection 5 second projection 6 gap 7 guide groove 8 guide projection 9 pliers 0 deformation direction 1 winding space

Claims

Patent claims Method for producing a stator (1) for an electrical machine, wherein in a first step a coil carrier (2) with regularly spaced teeth (3) is provided and then in a second step several partial coils (4) are wound onto the teeth (3), wherein the partial coils (4) are connected to one another in groups towards an end face (5) of the stator (1) by means of connecting wires (6), characterized in that in a third step at least one connecting wire (6) is plastically deformed locally to form a loop region (7a) which is flared axially inwards, wherein at the same time the at least one connecting wire (6) is tensioned in the circumferential direction of the stator (1). Method according to claim 1, characterized in that several loop regions (7a, 7b) are formed distributed in the circumferential direction on one connecting wire (6) and/or distributed on several connecting wires (6). Method according to claim 1 or 2, characterized in that at least one first loop region (7a) is present which is flared out in a first axial direction and at least one second loop region (7b) is present which is flared out in a second axial direction opposite to the first axial direction. Method according to claim 3, characterized in that both the first and the second loop region (7a, 7b) are each located axially within a winding space (21) of the stator (1), the winding space (21) being axially delimited by the axially outermost tangential regions of the partial coils (4) and connecting wires (6). Method according to one of claims 1 to 4, characterized in that the at least one loop region (7a, 7b) is formed by means of a mechanical forming tool (8). Method according to one of claims 1 to 5, characterized in that the coil carrier (2) is received in the second step as a linear structure (10) in a holding device (9) and/or the coil carrier

(2) after the second step and before the third step is brought into an annular structure (11). Stator (1 ) for an electrical machine, with regularly spaced teeth

(3), comprising a plurality of partial coils (4) wound onto the teeth (3), the partial coils (4) being connected to one another in groups towards an end face (5) of the stator (1) by means of connecting wires (6), characterized in that at least one connecting wire (6) locally forms a loop region (7a) which is axially inwardly flared. Stator (1) according to claim 7, characterized in that at least one connecting wire (6) locally forms a loop region (7b) which is axially outwardly flared. Stator (1) according to claim 8, characterized in that the stator (1) has a winding space (21) which is formed in the axial direction by the partial coils

(4) and the connecting wires (6), wherein the axial boundary of the winding space (21) is defined by the tangentially extending regions of the partial coils (4) and connecting wires (6) which are located axially furthest outward in relation to the stator (1), and the loop regions (7a, 7b) are formed axially within the winding space (21) and do not exceed its axial boundary. Stator (1) according to one of claims 7 to 9, characterized in that the stator (1) is manufactured according to a method according to one of claims 1 to 6. Forming tool (8) for forming a loop region (7a, 7b) on a stator coil, with two forming jaws (12, 13) which are movable relative to one another in a predetermined deformation direction (20), wherein on a first forming jaw (12) two spaced-apart, each transverse to the Pin-shaped first projections (14) running in the deformation direction (20) are arranged and a pin-shaped second projection (15) also running transversely to the deformation direction (20) is arranged on a second forming jaw (13), the forming jaws (12, 13) being designed such that the second projection (15) can be pushed in and out of an intermediate space (16) between the two first projections (14). Forming tool (8) according to claim 7, characterized in that the projections (14, 15) run parallel to one another and/or perpendicular to the deformation direction (20). Forming tool (8) according to claim 7 or 8, characterized in that the first forming jaw (12) has a guide groove (17) between the first projections (14), into which guide groove (17) a guide projection (18) designed complementarily to it can be pushed. Forming tool (8) according to one of claims 7 to 9, characterized in that the forming jaws (12, 13) directly form jaws of a pair of pliers (19).