ELECTRIC MACHINE WITH BENDING LOOPS, ELECTRIC LADDERS AND SHAPING INSULATION

Description

State of the art

[0001] The present invention relates to an electric machine with a rotor and a stator. The rotor and / or stator have a plug-in winding formed from flexible electrical conductors and shape-giving insulation. The present invention also relates to a method for manufacturing electrical conductor elements for a plug-in winding for a rotor and / or a stator of an electric machine.

[0002] Furthermore, the present invention relates to a forming device for the production of electrical conductor elements for a plug-in winding for a rotor and / or a stator of an electric machine.

[0003] In the transition from the use of fossil fuels to renewable energies, the type of vehicle propulsion has also moved into focus. Due to stricter legal requirements regarding vehicle pollutant emissions, the development of alternative vehicle propulsion systems has accelerated in recent years.

[0004] The development of purely electric drives is playing an increasingly important role in the development of sustainable vehicle propulsion systems. Automakers are further developing electric drive systems to offer an efficient and practical alternative to the combustion engine.

[0005] The winding technology for the coil windings of a stator and rotor in an electric machine significantly influences the machine's performance and efficiency. Therefore, coil winding processes are a key focus in the manufacturing and development of high-performance coil windings for electric motors used in vehicle propulsion.

[0006] From WO 2007 / 124985 A1, it is known to form the stator winding of an electric machine using plug-in technology. Insulated conductor elements are inserted into a stator body. The individual inserted conductor elements are then connected together to form the winding of the respective stator. To obtain the desired shape of the individual conductor elements, the insulated conductor elements are bent into their desired shape by several bending operations before being inserted into the stator body. The conductor elements have an electrically insulating sheath.

[0007] Electrical conductors comprising a multitude of fibers and enclosed by an insulating sheath are known from WO 2018 / 210479 A1, WO 2018 / 177767 A1 and JP 2020 018169 A. Disclosure of the invention

[0008] The electrical machine according to the invention features, in particular, an optimized power density. The electrical machine comprises a rotor and a stator, wherein the rotor and / or the stator have a plug-in winding. The plug-in winding comprises several rigid, insulated electrical conductor elements, wherein the conductor elements are arranged in slots of the stator or the rotor. Conductor ends protrude from the slots, and the conductor ends of each conductor element are connected to conductor ends of other conductor elements to form the electrical plug-in winding. Each conductor element has an insulating sheath. Furthermore, each conductor element has a plurality of electrically conductive, flexible fibers, which are, in particular, a strand of flexible fibers.This multitude of fibers is enclosed in a tubular insulating sheath. The insulating sheath is also designed to give the electrical conductor element a rigid shape. The insulating sheath is thus particularly tubular or sleeve-shaped, and the flexible fibers are arranged within it. The insulating sheath preferably enables the formation of conductor elements with minimized volume and maximized fill level.

[0009] The flexible fibers are made of carbon nanotubes or graphene. Carbon nanotubes or graphene exhibit particularly high electrical conductivity and, at the same time, low density.

[0010] Furthermore, the use of carbon nanotubes or graphene enables a particularly high filling density of the conductor elements and thus a particularly high fill factor of the electrical machine. Consequently, the power density of the electrical machine can be increased. Additionally, the higher electrical conductivity of the conductors allows for a reduction in material usage, which, together with the low density of the conductors, leads to a reduction in the weight of the electrical machine and lower manufacturing costs.

[0011] In contrast to the previous plug-in winding, this design utilizes a multitude of electrically conductive, flexible fibers instead of a bent copper conductor that retains its shape after bending. Therefore, unlike the copper plug-in windings known from the prior art, the shape of the conductor element is not determined by the flexible fibers, but by the rigid insulating sheath. Consequently, the plastic deformation property previously required for copper conductors is no longer a prerequisite for selecting the conductor material. This also enables the use of flexible electrical conductors, i.e., fibers, significantly expanding the range of available materials. In particular, this allows the use of the previously described low-density materials, thereby reducing the overall weight of the electrical machine.

[0012] Furthermore, the use of flexible fibers can achieve a higher fill factor in the electric motor. A flexible material is generally characterized by a low modulus of elasticity and high deformability due to low forces and moments. Typically, the weight of a flexible fiber is sufficient to deform the material.

[0013] Flexible fibers do not have a rigid shape and therefore cannot be bent into a specific, predefined form. They are thus arranged within the insulating sheath to maintain a fixed shape. In contrast, a rigid material is defined by the fact that a fixed shape can be maintained after a forming process without the support of an additional element or material. A significant change in shape can only be achieved by applying considerable force. The conductor's own weight is certainly insufficient.

[0014] The dependent claims describe preferred embodiments of the invention.

[0015] The insulating sheath is advantageously heat-shrinkable onto the numerous flexible fibers. This allows for simple and cost-effective assembly of the electrical conductor element. The insulating sheath is particularly advantageous when it is a heat-shrink tube. This enables simple yet reliable shaping of the electrical conductor element.

[0016] The insulating sheath is particularly advantageous because it effectively tensions the numerous flexible fibers, especially those in the conductor strand. This creates a tension force within the insulating sheath, resulting in a dense packing of the flexible fibers within the electrical conductor element. Consequently, the low volume and high fill level described above can be achieved.

[0017] Preferably, the insulating sheath is made of a thermoplastic material, in particular polyetheretherketone (PEEK). PEEK is a thermoplastic material that, due to its high-temperature resistance and its resistance to high-energy electromagnetic waves, is suitable for use as an insulating sheath for electrical conductors in electrical machines. Unlike other plastics, PEEK has a comparatively high melting point, which means it is not affected even at higher operating temperatures of the electrical machine. Furthermore, its thermoplastic formability makes PEEK particularly suitable for creating rigid shapes for the electrical conductors in a customized and flexible manner.Polyetheretherketone, for example, can be made into a largely rigid, shape-defining element by heating. This allows for the production of conductor elements with different geometries and dimensions with relatively little effort. However, other thermoplastics are also conceivable, which either already have a largely rigid form or can be cured using a process, such as the application of heat.

[0018] In a preferred embodiment, the insulating sheath is made of an insulating material with a negative coefficient of thermal expansion. This allows the insulating sheath to be applied to the fibers easily and reliably, ensuring the fibers are securely held within it. Heating of the electrical conductor element thus results in a tighter hold of the conductor element due to the negative expansion, i.e., shrinkage, of the insulating sheath.

[0019] In one embodiment, each conductor element can be U-shaped or I-shaped. It is also preferred that the conductor elements have a square, particularly rectangular, cross-section. This shape of the conductor elements allows for simple interconnection of the individual conductor elements. A U-shaped conductor element is particularly preferred because it means the plug-in windings only need to be connected at one end of the rotor and / or stator, thus reducing the interconnection effort and consequently the manufacturing effort of the electric machine. Furthermore, this reduces the number of connection points in the rotor and / or stator, further reducing assembly effort. Additionally, it allows for a reduction in the dimensions of the electric machine's housing, thereby further increasing its power density.

[0020] The invention also relates to a method that improves the production of plug-in windings for rotors and / or stators of an electric machine. This method for producing essentially rigid insulated electrical conductor elements for a plug-in winding for a rotor and / or a stator of an electric machine, in particular an electric drive motor for an electric vehicle, comprises in particular the following steps: First, a strand of flexible carbon nanotube or graphene fibers is enclosed with a tubular insulating sheath to form a conductor element. The insulating sheath is preferably thermoplastically deformable. Then, the conductor element is arranged in a recess of a forming device. The recess thus shapes the conductor element.The conductor element is then heated in the recess of the forming device using at least one heating element. Heating is carried out to a temperature that causes thermal shrinkage, in particular contraction, of the insulating sheath. This preferably results in the fibers arranged within the insulating sheath being pressed tightly together and against the insulating sheath itself. This allows for dense fiber packing. After heating, the conductor element is cooled. The heating and / or cooling process also preferably hardens the insulating sheath, so that the electrical conductor element retains the shape defined by the recess. The insulating sheath is responsible for shaping the conductor element.In contrast to the known bending process for insulated copper conductors, the shaping of the conductor elements is achieved not by bending, but by arranging the insulating sheath and the flexible, electrically conductive fibers in the recess formed in the shaping device and subsequently heating the insulating sheath. The shape of the recess essentially corresponds to the desired shape of the conductor element. Advantageously, the shaping and insulation of the electrical conductors are carried out in a single process step, thus reducing the number of process steps. The inventive method allows for the flexible, rapid, and precise formation of different shapes of conductor elements. This enables the use of different shaping devices to produce conductor elements with varying geometries and dimensions.The insulating sheath is advantageously flexible before the application of heat and can be deformed non-destructively without the application of high forces. However, the flexible insulating sheath does not retain its shape without the assistance of external forces. In the method according to the invention, the flexible insulating sheath is held in the desired shape before heating by means of the shaping depression. The insulating sheath is preferably sleeve-shaped or tubular. Preferably, the flexible fibers are guided through the sleeve-shaped or tubular insulating sheath. The insulating sheath can also comprise several segments that are inserted along the course of the depression and enclose the flexible fibers section by section, preferably immediately adjacent to each other. The individual segments can preferably be bonded together by heating.The insulating sheath is preferably made of a thermoplastic material, in particular polyetheretherketone. A curing process, preferably with passive temperature reduction, can be carried out by heating and cooling. The temperature reduction can be achieved, for example, simply by interrupting the heat supply. Alternatively, the curing process can include active temperature reduction, such as active cooling, particularly by cooling elements and / or forced convection. Preferably, the curing process of the conductor elements takes place in the recess of the forming device. In particular, a negative temperature coefficient of the insulating sheath causes tension in the flexible fibers within the insulating sheath and enables the entire cross-sectional volume of the conductor element to be filled.This process fully forms the shape of the conductor element, resulting in a compact conductor element with a high fill density. The conductor element can then be removed from the forming device's recess without any stress. Brief description of the drawing

[0021] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows: Figure 1 is a schematic view of an electric machine according to an embodiment of the invention. Figure 2 is a schematic view of a stator of the electric machine according to an embodiment of the invention. Figure 3 is a schematic partial view of the stator of the electric machine according to an embodiment of the invention. Figure 4 is a schematic view of a section through an electrical conductor element of a plug-in winding of the stator of the electric machine according to an embodiment of the invention. Figure 4A is a schematic view of an end region of the electrical conductor element of a plug-in winding of the stator of the electric machine according to an embodiment of the invention. Figure 5 is a schematic view of another electrical conductor element of the plug-in winding of the stator of the electric machine according to an embodiment of the invention.Figure 6 shows a schematic view of a forming device for carrying out a manufacturing process for the electrical conductor elements of the plug-in winding of the stator of the electric machine according to the embodiment of the invention. embodiment of the invention

[0022] Figure 1 Figure 1 schematically shows an electric machine 1 according to an embodiment of the invention. The electric machine 1 has a rotor 3 and a stator 2. The stator 2 is arranged on a housing 2a, wherein a rotor shaft 3a is rotatably mounted on the housing 2a, and the rotor 3 is attached to the shaft. Thus, the rotor 3 is rotatable about a central axis 100, which is also a central axis of the stator 2. The electric machine 1 is particularly advantageous as a drive system for a vehicle, for example, an automobile or a bicycle.

[0023] Figure 2Figure 1 schematically shows the stator 2 of the electric machine 1 according to the embodiment of the invention. The stator 2 has a stator base 6 to which a plug-in winding 4 is attached. The plug-in winding 4 is composed of a plurality of individual rigid insulated electrical conductor elements 5. This is shown in Figure 3 As shown, a plurality of I-shaped and / or U-shaped conductor elements 5 are provided, wherein these conductor elements 5 are inserted into stator slots 7 of the stator base body 6. Conductor ends 17 of the electrical conductor elements 5 protrude from the stator slots 7, wherein the conductor ends 17 of the conductor elements 5 are appropriately connected to conductor ends 17 of other conductor elements 5 to form the plug-in winding 4, in particular to realize three separate winding strands on the stator base body 6. The stator base body 6 is advantageously stacked from a plurality of individual laminations, wherein Figure 3For the sake of simplicity and clarity, only a single one of these stator laminations is shown.

[0024] The plug-in winding 4 constructed in this way allows high electrical currents to flow through the electrical conductor elements 5. In particular, the individual conductor elements 5 have a larger cross-section compared to conventional conductors. Specifically, they have a rectangular cross-section. This increases the current-carrying capacity of the individual conductor elements 5, resulting in a high output power for the electric machine 1.

[0025] Figure 4 Figure 1 shows a section through one of the insulated electrical conductor elements 5 used to manufacture the plug-in winding 4. The electrical conductor element 5 is in the Figure 2 The illustrated embodiment is I-shaped. Figure 4A shows an end area of ​​conductor element 5.

[0026] The insulated electrical conductor element 5 comprises a plurality of flexible, electrically conductive fibers 8, in particular a conductor strand of flexible fibers 8, made of carbon nanotubes (CNTs). The flexible fibers 8 are arranged within a sleeve-shaped or tubular and substantially rigid electrically insulating sheath 9. The insulating sheath 9 is preferably made of plastic, in particular polyetheretherketone (PEEK).

[0027] At the conductor ends 17 of the conductor element 5, fiber ends 18 of the fibers 8 protrude from the insulating sheath 9 and are therefore not electrically insulated. These fiber ends 18 serve in particular for electrically connecting two conductor elements 5 to create the plug-in winding 4 as described above.

[0028] The flexible fibers 8 preferably exhibit textile-like behavior. Therefore, the flexible fibers 8 can preferably be arranged with a high density within the insulating sheath 9. The insulating sheath 9 thus determines the shape of the conductor element 5, as the rigid insulating sheath 9 gives the conductor element 5 a rigid shape. Furthermore, the large number of flexible fibers 8 ensures a high current-carrying capacity, while the use of carbon nanotubes results in a low density and therefore low weight of the conductor element 5. This allows the electric machine 1 to be provided with a high power density.

[0029] Figure 5 Figure 1 shows another embodiment of an insulated electrical conductor element 5 with a plurality of flexible fibers 8. In contrast to the one in Figure 2, the fibers in Figure 3 are in a different configuration. Figure 4 In the illustrated embodiment, the insulated electrical conductor element 5 is shown according to Figure 5 U-shaped.

[0030] The U-shaped insulated electrical conductor element 5 comprises two legs 10 connected by a transverse section 11. Except for its shape, the structure of the element differs from that of the U-shaped insulated electrical conductor element 5. Figure 4 The exemplary embodiment of the conductor element 5 shown does not differ from the one in Figure 5 The illustrated embodiment of the conductor element 5. This is also the case in Figure 5 A sleeve-shaped or tube-shaped insulating sheath 9 is shown, in which several flexible fibers 8 are arranged. The flexible fibers 8 thus extend from one leg 10 across the transverse region 11 to the other leg 10 and protrude from the insulating sheath 9 at conductor ends 17 on the legs 10 with fiber ends 18. The advantages of the electrical conductor element 5 according to the one shown in Figure 5 The illustrated embodiments are the same as those of the one in Figure 4 illustrated embodiment of the electrical conductor element 5.

[0031] In both embodiments, the conductor ends 17 of the conductor elements 5 can be electrically contacted to connect the respective conductor element 5 to other components. In particular, the conductor elements 5 can be contacted with each other to form the plug-in winding 4. Thus, the conductor elements 5 can be used in the same way as conventional plug-in winding components.

[0032] Figure 6 Figure 12 shows a forming device 12 for producing the insulated electrical conductor elements 5 already described according to a method according to the invention. The forming device 12 shown by way of example serves in particular for producing the insulated electrical conductor elements 5. Figure 5 shown insulated electrical conductor element 5.

[0033] The forming device 12 has a base body 13 and a recess 14 formed in the base body 13. The recess 14 is U-shaped and has, in particular, a square or rectangular cross-sectional shape. Furthermore, another orientation of the recess 14 is also conceivable, in particular an I-shaped orientation for producing the Figure 4 shown insulated electrical conductor element 5.

[0034] The forming device 12 comprises a plurality of heating elements 15, which are attached to the base body 13 and distributed around the recess 14. The heating elements 15 preferably have an elongated shape extending along the recess 14. However, it is also conceivable to arrange a plurality of point heating elements 15 along the recess 14.

[0035] The heating elements 15 are preferably designed as thermocouples. Alternatively, they can also have a design such as a heating wire. The heating elements 15 are preferably screwed into the base body 13. However, a plug connection between the heating elements 15 and the base body 13 is also conceivable.

[0036] To produce the insulated electrical conductor elements 5, a plurality of electrically conductive, flexible fibers 8 are first guided through an insulating sheath 9. The insulating sheath 9 is sleeve-shaped or tubular with a square or round cross-sectional shape and does not yet have to have the final shape of the conductor element 5 at this point. Subsequently, the insulating sheath 9 with the flexible fibers 8 arranged therein is placed in the recess 14 formed in the base body 13 of the forming device 12.

[0037] After the insulating sheath 9 and the flexible fibers 8 have been arranged in the recess 14, the insulating sheath 9 is heated by means of the heating elements 15.

[0038] The insulating sheath 9 is preferably a thermoplastic polymer, in particular polyetheretherketone (PEEK). During the manufacture of the conductor element 5, the insulating sheath 9 is heated to the thermoplastic range. The thermoplastic range is the temperature range in which the heated insulating sheath 9 remains plastically deformed, i.e., does not return to its original shape.

[0039] The heat supply is then interrupted by the heating elements 15, allowing the insulating sheath 9 to preferably harden. This hardening can occur passively, meaning the insulating sheath 9 cools down solely due to the interruption of the heat supply, without any additional measures. However, hardening can also be carried out actively, for example, with additional cooling elements and / or with means that induce forced convection. Preferably, in both cases, the insulating sheath 9 remains in the recess 14 during hardening to allow the conductor element 5 to fully form. This results in a high fill density for the conductor element 5.

[0040] Subsequently, the conductor element 5, which essentially retains the shape of the recess 14, can be removed from the recess 14 in one piece. The conductor element 5 now has the fixed shape achieved by the process.

[0041] The insulating sheath 9 is preferably a heat-shrink tube and / or is made of a material with a negative coefficient of thermal expansion. Thus, the insulating sheath 9 is preferably thermally shrunk onto the plurality of flexible fibers 8 and is preferably designed to exert a tension force on the flexible fibers 8 located within the insulating sheath 9, in particular the conductor strand, when heated by the heating elements 15. This results in a dense packing of the fibers 8 and therefore a high filling density of the conductor element 5. Together with the low density of carbon nanotubes, this allows for a high current-carrying capacity of the plug-in winding 4 formed from the conductor elements 5, while simultaneously achieving low weight. The electric machine 1 thus exhibits a high power density.

Claims

1. Electric machine (1) having a rotor (3) and a stator (2), wherein the stator (2) and / or the rotor (3) has an electrical plug-in winding (4), which comprises a plurality of rigid insulated electrical conductor elements (5), wherein the conductor elements (5) are arranged in grooves of the stator (2) or the rotor (3) and project out of the grooves with their conductor ends (17), wherein the conductor ends (17) of the conductor elements (5) are each connected to conductor ends (17) of other conductor elements (5) to form the electrical plug-in winding (4), wherein the conductor elements (5) have an electrically insulating insulation sheath (9), characterized in that each conductor element (5) comprises a multiplicity of flexible fibres (8), in particular of a conductor bundle of flexible fibres (8), made of carbon nanotubes or graphene, and in that the insulation sheath (9) tubularly surrounds the multiplicity of fibres (8) and is designed in such a way that it gives the electrical conductor element (5) a rigid form.

2. Electric machine (1) according to Claim 1, characterized in that the insulation sheath (9) is thermally shrunk onto the multiplicity of flexible fibres (8).

3. Electric machine (1) according to one of the preceding claims, characterized in that the insulation sheath (9) braces the multiplicity of flexible fibres (8), in particular the conductor bundle, in the insulation sheath (9) with a tensile force.

4. Electric machine (1) according to one of the preceding claims, characterized in that the insulation sheath (9) is formed from a thermoplastic material, in particular from polyether ether ketone.

5. Electric machine (1) according to one of the preceding claims, characterized in that the insulation sheath (9) consists of an insulation material which has a negative coefficient of expansion.

6. Electric machine (1) according to one of the preceding claims, characterized in that each conductor element (5) is designed in a U shape or I shape and has a quadrangular, in particular rectangular, cross section.

7. Electric machine (1) according to one of the preceding claims, characterized in that the flexible fibres (8), in particular the conductor bundle, of each conductor element (5) project out of the respective insulation sheath (9) with their flexible fibre ends (18) at the two conductor ends (17) of the respective conductor element (5) in order to electrically connect the respective conductor element (5) to other conductor elements (5).

8. Method for producing substantially rigid insulated electrical conductor elements (5) for a plug-in winding (4) for a rotor (3) and / or a stator (2) of an electric machine (1), in particular an electric drive machine for an electrically driven vehicle, having the following steps: - surrounding a bundle of flexible fibres (8) made of carbon nanotubes or graphene with a tubular insulation sheath (9) to form a conductor element (5), - arranging the conductor element (5) in a shaping depression (14) of a shaping device (12), - heating the conductor element (5) in the depression of the shaping device (12) by means of at least one heating element (15) to a temperature which effects thermal shrinking, in particular a contraction, of the insulation sheath (9), and - cooling the conductor element (5).