Radial Flux Double Rotor Machine

Abstract

The present invention relates to a stator having a stator core and a winding with high torsional rigidity accommodated therein, wherein a conductor bar of the winding with high torsional rigidity extends spirally in a first rotation direction in the radially inner portion, and a conductor bar of the winding with high torsional rigidity extends spirally in the opposite second rotation direction in the radially outer portion; and a double rotor having an inner rotor and an outer rotor, wherein the inner rotor and the outer rotor each have a common central axis with an annular base designed for magnetic flux propagation, and a plurality of permanent magnets are fixed to the annular base respectively, a predetermined angular section of the annular base is assigned to each permanent magnet, and the permanent magnets are formed and arranged on each annular base such that a predetermined angular section is displaced circumferentially along an axial path, generating a magnetic field extending obliquely with respect to the central axis, the magnetic field of the inner rotor extending obliquely in a first direction toward the first rotation direction, and the magnetic field of the outer rotor extending obliquely in a second direction toward the second rotation direction, particularly relating to a radial flux double rotor machine for driving a wheel hub.

Description

Technical Field

[0001] The present invention particularly relates to a radial flux double rotor machine for wheel hub drive.

Background Art

[0002] An electric machine having one stator and two rotors connected in the rotational direction, so-called double rotor machine (also called multi-rotor, dual-rotor, etc. in addition to double rotor), can improve both torque density and electric drive efficiency compared to a conventional electric machine having only one rotor. The reason is that, particularly in the so-called "yokeless" design, a magnetic return path (back iron) is not required for the stator, and as a result, magnetic losses can be significantly reduced. Furthermore, the presence of two rotors basically increases the space available for the field excitation magnets (in the case of a permanent magnet synchronous machine PSM) or the conductor material (in the case of an induction machine IM or an electrically excited synchronous machine ESM). Depending on the direction of the magnetic field lines in the air gap, such machines can be divided into two groups: on the one hand, axial magnetic field lines (magnetic field lines parallel to the rotation axis, so-called axial flux machines), and on the other hand, radial magnetic field lines (radial magnetic field lines in the air gap, so-called radial flux machines).

[0003] Axial flux double rotor machines are described, for example, in German Patent Application Publication No. 102015226105 and German Patent Application Publication No. 102013206593. These machines are characterized by high torque and power density, but the manufacturing cost is high because the stator core needs to be manufactured by pressing or powder metallurgy with a very complex shape. Therefore, so far, these machines have not been mass-produced and have only been used in niche fields where high power density is required, such as applications in racing, aerospace, etc. Furthermore, the mechanical mounting concept of the stator winding only enables the use of single-tooth windings, which has corresponding demerits in terms of noise excitation.

[0004] In contrast, in the case of a radial flux double rotor machine, a manufacturing method that is principled and suitable for mass production can be used due to the windings and laminated cores. However, in this case, a major technical problem remains of supporting the torque generated in the stator core. Due to the components rotating on the inner and outer sides, the laminated stator core cannot be attached to a fixed housing (e.g., press-fitting, fastening, or adhesion) as in the normal case. Therefore, the torque is guided to both axial ends of the laminated stator core or the stator windings and supported at that position. Regarding this point, various approaches have been proposed in the prior art, but all of them have significant disadvantages in terms of function and / or cost.

[0005] European Patent No. 1879283 discloses one method of designing the stator windings as so-called yoke windings. In this case, the annular laminated stator core has grooves in the inner diameter and outer diameter, and has a magnetic return path (also called the stator yoke) acting in the tangential direction between them. The forward conductor and the return conductor of each winding strand are led into grooves overlapping each other in the radial direction and wound around the yoke. The stator yoke is axially accessible between the winding strands and can be fixed to the housing, for example, by an axial screw connection (described in, for example, Japanese Unexamined Patent Application Publication No. 2018 - 082600). The axial pressure of the screw can ensure both the torsional rigidity of the laminated core and the torque support at the axial ends. The N pole and the S pole of the rotor magnetic field are arranged opposite to each other. The drawback of this concept is that the magnetic flux has to be completely propagated through the return yoke between the stator grooves. This increases the weight of the laminated stator core and significantly increases the iron loss.

[0006] The magnetic field lines of both rotors are closed via the magnetic return path within the laminated stator core, where iron losses are generated. Further, all individual coils of the yoke winding must be connected in parallel or in series in the region of the winding head, resulting in a conflict for the installation space with torque support. However, the winding wound around the yoke allows direct mechanical contact with the laminated stator core.

[0007] If the magnetization direction of the magnet where one point extends in the same direction radially above another point and the current direction of the conductor where one extends above another within the slot are the same, significant weight and loss reduction can be achieved. In this case, the magnetic return path in the stator can be omitted, and a so-called "yokeless" double-rotor machine with distributed windings is created. The magnetic field lines close on the rotor. Since the magnetic return path within the stator is unnecessary, the weight and iron losses in such a machine are very low. However, distributed windings do not allow direct mechanical contact with the laminated stator core for torque support. For example, International Publication No. WO 2004 / 004098 describes a yokeless design using distributed windings.

[0008] Regarding axial support, various auxiliary structures for torque support have been proposed as prior art, as described, for example, in German Patent Publication No. DE 102010055030 or U.S. Patent No. 7,557,486. The problem here is that a metal, which is electrically and / or magnetically conductive, is not allowed to protrude into the magnetic flux propagation region, or can only protrude within a very limited range, thereby significantly restricting the material selection and shape design. In contrast, synthetic material parts, adhesives, and / or casting (potting) materials can also be used in the magnetic flux propagation region. However, it is very difficult to meet the high requirements regarding temperature stability and mechanical strength with these materials. SUMMARY OF THE INVENTION

[0009] Against this background, the present invention is based on the problem of providing an improved radial flux double rotor machine. According to the present invention, this problem is solved by a radial flux double rotor machine having the features of claim 1.

[0010] Therefore, A stator having a stator core and a highly torsionally rigid winding housed in the stator core, wherein on the radially inner side, the conductor bars of the highly torsionally rigid winding extend spirally in a first rotational direction, and on the radially outer side, the conductor bars of the highly torsionally rigid winding extend spirally in a second rotational direction opposite thereto; and a double rotor having an inner rotor and an outer rotor, wherein the inner rotor and the outer rotor each have a common central axis with an annular base designed for magnetic flux propagation, and a plurality of permanent magnets are fixed to the annular base respectively, a predetermined angular section of the annular base is associated with each permanent magnet, and the permanent magnets are designed and arranged on their respective bases such that the angular sections are displaced circumferentially in the axial path, whereby the permanent magnets generate a magnetic field extending obliquely with respect to the central axis, the magnetic field of the inner rotor extends obliquely in a first direction directed in the first rotational direction, and the magnetic field of the outer rotor extends obliquely in a second direction directed in the second rotational direction. In particular, a radial flux double rotor machine for driving a wheel hub is provided.

[0011] The insight underlying the present invention is that in a radial flux double rotor machine, magnetic field distortion can exist due to changes in the axial magnetic field. The magnetic field has its full amplitude only at the axial center of the machine. At both axial ends of the machine, the amplitude of the magnetic field weakens. Another underlying discovery is that magnetic field distortion leads to a shift in the maximum value of the magnetic field, resulting in a reduction in torque.

[0012] The underlying idea of the present invention is to provide a combination of special electrical synchronous machines having a double rotor, wherein the stator has a stator core for torque support and highly torsionally rigid windings accommodated therein, and permanent magnets arranged circumferentially shifted along the axial direction of each rotor to generate a skew magnetic field.

[0013] The individual conductor bars of the highly torsionally rigid windings are axially arranged along the helix of the stator slots and the first and second rotational directions corresponding to the radially inner and outer stator slots, and are connected at the ends of the conductors. A material connection by welding or soldering is preferably provided for this purpose. However, other connection techniques are also conceivable. Preferably, two conductor bars are connected at the ends of each conductor bar, and all the conductor bars together form a bar structure. The windings are thus formed in particular from conductor bars connected to each other in the form of a bar structure. The bar structure formed by the conductor bars advantageously has a high torsional rigidity and is designed to transmit the moment about the central axis of the stator. Thereby, the windings are given a highly torsionally rigid shape, and the windings are connected to the stator core by fitting for torque support.

[0014] Furthermore, the conductor bars are designed to have a thickness sufficient for power transmission. For example, in a wheel hub motor, the thickness of the conductor bars can be in the range of several millimeters. In particular, the conductor bars may have a square cross-sectional shape with a side length of several millimeters.

[0015] The selected lead angle (which is also the setting angle) of the stator slots or the helix depicted thereby ensures that a conductor loop is formed by the connection of the inserted conductor bars. The angle of the conductor loop in the machine is swept with respect to the central axis and surrounds one pole of each rotor. In this way, despite the functional integration, a very simple manufacture of the stator becomes possible, obtained with very few parts and relatively simple conventional connection techniques, and thus the manufacturing process is also very few.

[0016] The stator designed in this way, together with the inner rotor and the outer rotor according to the present invention, can be completed to constitute the electromechanical device according to the present invention. The winding with high torsional rigidity includes dividing the stator into a radially inner part and an outer part. The conductor bars of the winding with high torsional rigidity in the radially inner part are arranged spirally in the first rotation direction, and the conductor bars of the winding with high torsional rigidity in the radially outer part are arranged spirally in the opposite second rotation direction. Thereby, since the conductor bars are continuously displaced (in the tangential direction) in the axial position of the electromechanical device, the magnetic field generated by the winding with high torsional rigidity changes in the axial position of the electromechanical device. As a result, the magnetic field has a maximum amplitude only at the axial center of the electromechanical device where the conductor bars with the same strand and current direction overlap. Due to the basic shape, the amplitude of the magnetic field decreases towards both axial ends of the electromechanical device. Regarding the resulting linked magnetic flux and the torque of the electromechanical device, the average value over the entire length is particularly important.

[0017] In addition to the decrease in the amplitude of the magnetic field, at both axial ends of the electromechanical device, due to the rotational displacement of the conductor bars relative to each other, a distortion of the magnetic field in the tangential direction also occurs, leading to a displacement in the tangential direction of the maximum value of the magnetic field. Such a distortion of the magnetic field leads to a decrease in torque in the conventional permanent magnet arrangement because the permanent magnets of the rotor are not in the optimal position for torque generation.

[0018] Therefore, according to the present invention, the decrease in torque due to the distortion of the magnetic field is offset by the new arrangement of the permanent magnets. For this purpose, the permanent magnets of each rotor are axially shifted along the circumferential direction to generate an oblique magnetic field. The generated obliquely inclined magnetic fields of the inner rotor and the outer rotor extend in two opposite inclined directions and correspond to the respective opposite rotation directions of the conductor bars of the winding with high torsional rigidity. Advantageously, the axial displacement of the permanent magnets along the circumferential direction according to the present invention has a positive effect on the generated torque, and in particular enables a torque increase of up to 10% compared to the non-inclined arrangement of the permanent magnets in the inner rotor and the outer rotor.

[0019] The rotor is preferably made of a soft magnetic solid material and has permanent magnets mounted on its surface. The small upper magnetic field spectrum of the winding variations described here and the distance of the solid material from the air gap ensured by the magnets can prevent the occurrence of unacceptably large losses due to eddy currents in the rotor. In this design, a relatively high efficiency can be advantageously achieved, and the rotor can still be manufactured at a very low cost.

[0020] In particular, the support device of the stator that engages with the winding having a particularly high torsional stiffness is firmly connected to the base as the stationary part of the electromechanical device in a suitable manner. One possible embodiment provides, for this purpose, recesses, such as through-holes, for non-fitting fasteners like screws. However, alternatively or additionally, the use of fitting fixtures and / or joining of materials will of course also be conceivable.

[0021] In particular, the present invention is particularly advantageously applicable, preferably, to wheel hub motors for automobiles. By integrating functions, the design according to the present invention makes it possible to reduce the mass of the radial flux double rotor machine and increase the torque density, which, advantageously, particularly means a reduction in the unsprung mass, especially in wheel hub motors. Furthermore, according to the present invention, a relatively short axial length can be realized with a relatively large diameter, which is particularly advantageous inside the wheel with respect to torque support and installation space.

[0022] On the other hand, according to the present invention, despite the extremely compact design, it is possible to obtain a very high torque that is sufficient to directly drive the vehicle wheels, particularly without a gearbox. In this way, transmission losses are particularly advantageously avoided, further weight is reduced, and a particularly high effect can be achieved.

[0023] Furthermore, this high torque can already reach into the four-digit range, in particular be greater than 1000 Nm, preferably greater than 1500 Nm, and particularly preferably exceed 5000 Nm, relative to the mounting size within the dimensions of conventional automotive wheels, and thus already reach the grip limit of conventional road tires, and it is even possible to replace the rear axle wheel brakes with wheel hub motors. In this way, when used as a wheel hub motor, special synergistic effects and functional integrations become possible.

[0024] Advantageous embodiments and further developments result from the further dependent claims, as well as the description with reference to the drawings.

[0025] According to a preferred embodiment, the annular base body is made of solid material. The highly torsionally rigid winding for the first time provides the possibility of designing the winding of a synchronous machine with a double rotor as a distributed winding with a corresponding small upper magnetic field spectrum. Since only a small upper magnetic field and the resulting eddy currents are generated in the rotor by the winding, the rotor can be manufactured from solid material only in this design. Thus, if the inner rotor and the outer rotor are made of a soft magnetic solid material, cost savings can be achieved by simplified manufacturing, and moreover, high efficiency can be achieved.

[0026] According to another embodiment, the permanent magnets are arranged at a predetermined inclination angle with respect to the axial direction of the central axis of the annular base body. In this way, the magnetic field generated by the permanent magnets can be aligned as desired with respect to the central axis of the annular base body, thereby generating a desired oblique magnetic field. Since the inclination angle is basically affected by the actual positioning and / or orientation of the permanent magnets, it can be adjusted freely. In this way, the reduction of torque due to magnetic field distortion can be advantageously compensated by setting a predetermined inclination angle.

[0027] According to other embodiments, the permanent magnets are each divided into a plurality of axial sections. Each axial section is assigned an angular section that is offset by an attack angle around the central axis with respect to an adjacent axial section. As a result, the total tilt angle around the central axis or in the circumferential direction is determined by the attack angle, in particular a multiple of the attack angle. Furthermore, the axial sections can be aligned with an edge parallel to the central axis of the annular substrate. The number of axial sections and the attack angle of the individual axial sections with respect to each other can be freely selected. In this way, a radial flux double-rotor machine that can be configured from the viewpoints of manufacturing cost and magnetic field optimization is provided.

[0028] According to other embodiments, for a predetermined number n of axial sections per permanent magnet, the resulting total tilt angle φ is obtained from the attack angle θ using the relationship φ = n×θ. Based on the mathematically simple relationship between the number of axial sections per permanent magnet and the attack angle, the individual parameters of the magnet arrangement of the rotor of the radial flux double-rotor machine according to the present invention can be calculated in a simple manner and can be easily implemented. Therefore, the radial flux double-rotor machine can be easily adapted to different requirements or designed accordingly.

[0029] According to other embodiments, the permanent magnets are each divided into two axial sections. In this way, a modification of the radial flux double-rotor machine according to the present invention, which is easy to manufacture and thus particularly advantageous in terms of manufacturing cost, is provided. Since the number of axial sections remains small, the alignment and assembly of the sections remain relatively simple, but the torque achievable during operation increases significantly.

[0030] According to other embodiments, the permanent magnets are aligned with their edges along a predetermined tilt angle. Accordingly, a radial flux double rotor machine is provided that can also be adjusted and designed using an integral permanent magnet in accordance with the requirements regarding the predetermined tilt angle. When the permanent magnets have a flat surface, if the permanent magnets are disposed obliquely on the inner peripheral surface or the outer peripheral surface of each annular base, due to their shape, a slight gap is generated between the permanent magnet and the base in some portions. This gap is preferably filled with a material connection medium when the permanent magnets are connected to the annular base by material connection. The material connection can be realized, for example, by an appropriate adhesive.

[0031] According to other embodiments, the permanent magnets have an oblique parallelogram shape. The parallelogram-shaped permanent magnets also have one, in particular the same, resulting total tilt angle in the circumferential direction. In this way, it is possible to avoid leaving the surface of the annular base empty or protruding from the surface by means of the parallelogram-shaped permanent magnets. As a result, the surface area of the annular base can be optimally utilized. When the parallelogram-shaped permanent magnets are arranged in / on the annular base, a gap is also generated due to the shape. However, this gap can be filled with a material connection medium, for example, when the permanent magnets are connected to the annular base by material connection. The material connection can be realized, for example, by an appropriate adhesive.

[0032] According to other embodiments, the permanent magnets can also be formed as rectangles, in particular narrow rectangles. Each corner of the permanent magnet can leave a relatively small surface area on each annular base empty or project a corner thereon. Since the dimensions of the permanent magnet, in particular its width, are selectable, the area left empty or protruding can thus also be adjusted. Accordingly, a radial flux double rotor machine is provided that can be designed in a simple way to meet the requirements. In other embodiments, other arrangements of the permanent magnets are also conceivable, resulting in the desired tilted magnetic field.

[0033] According to one embodiment, the winding is designed to have torsional rigidity such that the torque acting on the stator core during the operation of the radial flux double rotor machine can be supported by the support member, particularly completely, via a winding with high torsional rigidity. In this way, it is possible to advantageously omit all other types of force support devices for the stator core.

[0034] According to other embodiments, the winding has an inner radial layer of conductor bars spirally arranged on the inner side of the stator in the radial direction and an outer radial layer of conductor bars spirally arranged in the opposite direction on the outer side of the stator in the radial direction. In this way, the winding forms a bar structure with high torsional rigidity. The conductor bars on the inner side of the stator in the radial direction and the conductor bars on the outer side of the stator in the radial direction each depict a helix with opposite winding directions or pitches. The angle of the helix between the start and end of the conductor bar swept with respect to the central axis of the stator is designed such that, in particular, one conductor loop is formed for each magnetic pole of the rotor in the radial flux double rotor machine. Therefore, the provided sweep angle can be calculated from the quotient of the angle of one revolution (2π or 360°) and twice the number of pole pairs p.

[0035] According to one embodiment, the inner radial layer and the outer radial layer of the winding each have the thickness of an individual conductor bar. That is, one phase of the winding is formed by the cross-section of an individual conductor bar respectively. Such a winding design according to the present invention is made possible particularly by the special design of the radial flux double rotor machine, and its magnetic symmetry prevents current displacement to the surface that would otherwise exist in the conductor. In this way, a relatively thick conductor cross-section can be realized, and nevertheless a relatively uniform current distribution is achieved over the entire cross-section. For example, the thickness of the conductor bar can be in the range of several millimeters. In particular, the conductor bar can be a bar having a square cross-sectional shape with a side length in the range of several millimeters, for example, from 2 mm to 6 mm, particularly from 3 mm to 5 mm. Other cross-sectional shapes are also possible.

[0036] According to one embodiment, the conductor bars are each twisted along a helical path such that the cross-section of the conductor bar is the same at any point of the conductor with respect to the radial axis of the cross-section. In particular, this is related to the twist of the conductor bar, in particular of a non-circular conductor bar, around the central axis of the stator or machine. Depending on the helical shape of the path, the conductor bar may be further bent. In this case, the inner layer and the outer layer cross each other, i.e., are twisted in opposite directions to each other, and are twisted and possibly bent. In this way, the arrangement of the conductor bars is ideally arranged from a mechanical point of view at each point of the stator core for force transmission to the stator core, whereby each conductor bar is uniformly loaded over its length. As a result, in the bar structure, when the conductor bar is subjected to a tangential force, it preferably absorbs tensile and compressive stresses. In this way, load peaks and deformations of the conductor bar are avoided. In particular, the mechanical stress can be significantly reduced compared to a design using axially parallel straight conductors.

[0037] According to one embodiment, the conductor bars of the radially inner layer and the radially outer layer belonging to the same phase of the winding are connected to each other in each case at both ends of the conductor bar, in particular by conductor bar pieces arranged radially and / or by a material connection.

[0038] Thereby, in addition to the conductor loop, a bar structure with high torsional rigidity is also formed, so that when the axially accessible end of the winding is fixed, a high torque can be absorbed by the winding without causing an unacceptable large deformation and / or stress state. Thus, a self-supporting design of the winding is made possible by the winding material, for example, copper only, without additional supporting means or members.

[0039] According to another embodiment, the stator core comprises a laminated stator core having stator grooves extending spirally along the path of the winding. The inner stator grooves in the radially inner portion of the stator extend in a first rotational direction, and the outer stator grooves in the radially outer portion of the stator extend in opposite directions to each other in a second rotational direction. The winding or the self-standing bar structure formed using the same is embedded in the laminated stator core. Similar to the conductor bars of the winding, the stator grooves also have a tangential position that changes according to the axial position, forming a spiral shape. The direction of the change in position follows that of the conductor bars, that is, the center lines of the grooves on the radially outer side and the radially inner side also each draw a spiral with opposite rotational directions and corresponding to the first or second rotational direction respectively.

[0040] In other embodiments, other manufacturing methods known to those skilled in the art, particularly additional manufacturing methods such as a sintering process, may also be considered for manufacturing the shape of the stator core according to the present invention having radially inner and outer stator grooves extending in opposite spiral directions.

[0041] According to one embodiment, only a single conductor bar is disposed in each stator groove of the laminated stator core. As already explained in relation to the winding, the conductor bars in the inner and outer stator grooves cross each other spirally due to torsion around the central axis of the machine, and the ends of the conductors in the inner and outer layers are guided in directions towards each other. At both ends of the conductor bar, the conductor bars are connected to be electrically conductive with each other, particularly by conductor bar pieces disposed in the radial direction and / or by material connection such as welding or brazing.

[0042] According to one embodiment, the conductor bars, which are conductively connected between the inner layer and the outer layer, together form a wavy winding strand. The winding strands can be interconnected to form a rotating magnetic field generating winding having a desired or adjustable number of strands by suitable interconnections known to those skilled in the art. The number of phase windings for maintaining the voltage is directly obtained by the quotient of the number of grooves of the molecule and the product of the number of phase windings and the number of parallel branches of the molecule. Advantageously, the number of parallel branches is selected to be 1. In this case, the simplest interconnection of the windings is obtained.

[0043] According to one embodiment, the stator laminations of the laminated stator core are each formed in the same shape with a plurality of recesses provided to form stator grooves. The helical path of the stator grooves is provided by laminating the stator laminations in a twisted arrangement relative to each other. In this way, the laminated stator core can use the same mold for all stator laminations arranged or laminated in parallel and can be manufactured in a very economical way. Thus, two adjacent stator laminations are arranged slightly twisted relative to each other by a predetermined angle about the central axis, and the recesses are arranged to overlap each other corresponding to the helical path.

[0044] According to another embodiment, the laminated stator core includes an inner partial package having a radially inner stator groove and an outer partial package having a radially outer stator groove. The stator thin plates of the inner partial package are each designed in the same shape, and the stator thin plates of the outer partial package are each designed in the same shape. Further, the stator thin plates of the inner partial package are laminated according to the first rotation direction of the conductor bar, and the stator thin plates of the outer partial package are laminated according to the second rotation direction of the conductor bar, and are rotated in opposite directions to each other by a predetermined rotation angle around the central axis. In another embodiment, the twist angle of the stator thin plates around the central axis is the same as the sweep angle of the stator slots. In this way, the reverse helix of the stator grooves can be realized with little manufacturing effort. Nevertheless, the same mold can be used for all parallel or laminated stator thin plates of the inner partial package, and the same mold can be used for all parallel or laminated stator thin plates of the outer partial package, so a very economical manufacturing method is still possible. Therefore, two adjacent stator thin plates of the inner partial package are slightly twisted with respect to each other by a predetermined twist angle in the first rotation direction around the central axis, and two adjacent stator thin plates of the outer partial package are slightly twisted with respect to each other by a predetermined twist angle in the opposite second rotation direction around the central axis. In this way, the recesses of the stator thin plates of the inner partial package and the recesses of the stator thin plates of the outer partial package are arranged so as to overlap each other on opposite sides, which corresponds to the reverse helix.

[0045] According to one embodiment, the stator thin plates of the laminated stator core are each formed in the same shape having a plurality of recesses provided to form stator grooves. The spiral path of the stator grooves is provided by laminating the stator thin plates in a twisted arrangement. In this way, the same mold can be used for all parallel or laminated stator thin plates of the laminated stator core, and it can be manufactured in a very economical way. Therefore, two adjacent stator thin plates are arranged such that they are slightly twisted with respect to each other by a predetermined angle around the central axis, and the recesses are arranged so as to overlap each other corresponding to the helix.

[0046] According to another embodiment, the stator thin plates are formed with recesses provided for forming the stator grooves being different from each other. The spiral paths of the stator grooves are provided by different distances between the recesses in the individual stator thin plates. In this regard, for each position of the stator thin plates in the laminate, a shape of the stator thin plate that individually matches is manufactured, whereby the individual shapes can also be repeated within the laminate. In this case, the manufacturing can be realized, for example, by a laser cutting process, in particular a laser beam cutting process that has more degrees of freedom in terms of shape than a pressing process. Also, in the case of a cutting die with a high degree of freedom in variable shape or a very large quantity, it is of course conceivable to use several individual cutting dies for each of the shapes of the different stator thin plates.

[0047] According to another development, the recesses for the radially inner and radially outer stator grooves are integrally formed in a common stator thin plate, and the opposite spiral paths of the radially inner and radially outer stator grooves are brought about by the continuous displacement of the inner stator groove and the outer stator groove relative to each other from stator thin plate to stator thin plate. Also in this case, for each position of the stator thin plates in the laminate, a shape of the stator thin plate that individually matches is created, whereby the individual shapes can also be repeated within the laminate. Here too, a cutting process with a high degree of freedom such as laser beam cutting is used in the manufacturing. In this way, by the integral manufacturing of the inner recess and the outer recess, the number of parts can be effectively reduced.

[0048] According to one embodiment, the stator thin plate is linear, particularly having a punched edge. The width of the recess provided for the stator groove is larger than the width of the conductor bar by an amount predetermined by the helical pitch of the stator groove and the plate thickness of the stator thin plate. Therefore, the gap width or continuous width of the stator groove reduced by the offset between the recesses of the stator thin plate substantially corresponds to the width of the conductor bar. In practice, a continuous gap width of the stator groove slightly larger than the width of the conductor bar is provided to provide the clearance fit necessary for the insertion of the conductor bar. Therefore, the edges of the stator grooves are stepped with each plate thickness as a step, and the conductor bars are evenly supported there. In this way, torque support is evenly performed over the entire thickness of the laminated stator core or over the entire length of the conductor bar accommodated in the laminated stator core.

[0049] According to one embodiment, the angle swept by each stator groove is smaller than the angle swept by each conductor bar. The swept angle refers to the rotation around the central axis of the stator respectively. The difference in the swept angles is due to the fact that the conductor bar protrudes axially beyond the stator core and is longer than the stator groove. Since the spiral path is also continued, the swept angle consequently increases. This difference is provided to ensure sufficient accessibility of the ends of the windings for joining, particularly welding, the ends of the conductor bars after insertion into the stator grooves. Further, this enables the windings to engage with the support device or its support member in a state offset axially with respect to the stator core.

[0050] From the quotient of the swept angles, that is, the ratio of the angle swept by each stator groove to the angle swept by each conductor bar, a so-called magnetic pole coverage rate for the laminated stator core can be defined.

[0051] According to one embodiment, the ratio of the angle swept by each stator groove to the angle swept by each conductor bar is in the range between 0.6 and 0.8, particularly between 0.6 and 0.75, preferably between 0.6 and 0.7. This ratio (pole coverage factor) provides an optimal condition between current heat loss and torque utilization within this range.

[0052] According to one embodiment, the winding protrudes beyond the stator core at at least one axial end. Further, a support device is provided that is axially offset with respect to the stator core and is designed to engage with the winding by fitting at at least one axial end for torque support.

[0053] According to another advantageous development, the support device comprises a support member provided with support grooves corresponding to the helical arrangement of the conductor bars and engaging with the conductor bars. In this way, embedding by fitting of the conductor bars in the support member is provided for supporting torque at the axial ends. Preferably, it engages with all the conductor bars so that torque support is transmitted homogeneously or uniformly across the entire bar structure of the winding.

[0054] To transmit torque, the support member may be coupled to a mechanically fixed base of the radial flux double rotor machine. One possible design provides through holes for fixtures that are not fitting, like screws, but of course connections locked by fixtures or materials that lock by fitting are also conceivable.

[0055] According to one embodiment, the support grooves at least partially follow the helical path of the twisted conductor bars. In particular, the support grooves follow the same twisted path as the conductor bars. For example, the support member is essentially annular and has recesses on its inner and / or outer circumference that are radially aligned and correspond to the path of the conductor bars.

[0056] According to one embodiment, the support device has an inner support member for engaging with the radially inner layer of the conductor bar and an outer support member for engaging with the radially outer layer of the conductor bar. In this embodiment, the support member may be annular. The inner support member has, on its outer periphery, grooves or teeth corresponding to the path of the inner layer of the conductor bar for receiving the radially inner conductor bar by fitting. The outer support member has, on its inner periphery, grooves or teeth corresponding to the path of the outer layer of the conductor bar for receiving the radially outer conductor bar by fitting. In particular, the grooves or teeth are along their respective spiral paths. By arranging the concave grooves on the inner or outer periphery, they are easily accessible for machining, whereby the support member can be easily manufactured.

[0057] According to other embodiments, the total circumferential tilt angle of the permanent magnets of the inner rotor is in the range of 20% to 40%, preferably 25% to 35%, particularly preferably 28% to 32% of the twist angle of the stator thin plate of the inner partial package, and / or the resulting total circumferential tilt angle of the permanent magnets of the outer rotor is in the range of 20% to 40%, preferably 25% to 35%, particularly preferably 28% to 32% of the twist angle of the stator thin plate of the outer partial package. Due to the fact that the magnetic field distortion does not completely follow the path of the stator grooves of each stator thin plate, the resulting total tilt angles of the permanent magnets of the inner rotor and the outer rotor are smaller than the twist angle of the stator thin plate. In this way, a particularly advantageous design is provided that results in an optimized torque increase due to the ratio between the twist angle of the stator thin plate and the resulting total tilt angle of the permanent magnets.

[0058] According to other embodiments, the permanent magnets of the inner rotor and the outer rotor have a magnetic pole width in a predetermined tangential direction, and the stator core has a radial yoke thickness in the range of 5% to 25%, preferably 10% to 20%, particularly preferably 12.5% to 17.5% of the magnetic pole width in the tangential direction. The magnetic pole width in the tangential direction is, in particular, a local magnetic pole width in the tangential direction, and preferably represents the common tangential width of the magnetic poles of all the permanent magnets. Further, the maximum magnetic pole width in the tangential direction in the cross-section of the machine is calculated from the quotient of the product of the angle of one revolution (2π or 360°) and the radius of the machine and twice the number of magnetic pole pairs. In order to support a specific tangential magnetic flux at both ends of the radial flux double rotor machine, the radial yoke thickness of the stator core can be increased to reduce the magnetic resistance. Therefore, the adopted radial yoke thickness of the stator can be designed to increase slightly compared to the conventional yokeless design, but does not significantly increase the weight of the laminated stator core.

[0059] According to one embodiment, the stator core is still designed mainly to conduct the radial magnetic flux. Therefore, the so-called "yokeless" design of the stator core still has no significant magnetic flux guiding in the circumferential or tangential direction, particularly at the axial center of the machine.

[0060] According to one embodiment of the radial flux double rotor machine, the support member is fixed to the base, thereby guiding the torque to the stationary part of the electromechanical machine. For this purpose, the support member may be individually attached to the base of the machine, for example, the housing. Alternatively or additionally, the inner support member and the outer support member may be fixed to each other.

[0061] According to one embodiment of the stator, the support member includes a thermally conductive material, particularly a metal, preferably an aluminum alloy. In particular, both support members may include such a material. This enables heat dissipation from the winding through the support member in addition to high mechanical strength.

[0062] According to one embodiment of a corresponding radial flux double rotor machine comprising a support device including a thermally conductive material, the base further comprises a heat sink designed to absorb heat dissipated from the stator, in particular from the windings, via the support device. As a result, the support device has high mechanical strength and at the same time ensures good thermal connection of the windings to the heat sink. For example, the housing of the machine may function as a heat sink. Alternatively or additionally, the support device, preferably the inner and outer support members, may be brought into thermal contact with an actively cooled heat sink of the machine. In this way, the current heat losses generated in the windings or conductor bars can be effectively eliminated.

[0063] According to one embodiment of a radial flux double rotor machine, a predetermined number of pole pairs are provided on both the first rotor and the second rotor. The angles swept by the conductor bars are designed to form conductor loops for each pole of the rotor. Therefore, the swept angle can be calculated from the quotient of the angle of one revolution (2π or 360°) and twice the number of pole pairs p.

[0064] Another aspect of the present disclosure regarding a method of manufacturing a stator includes providing a stator core having radially outer stator grooves each depicting a helix having a first rotational direction and radially inner stator grooves each depicting a helix having an opposite rotational direction, inserting individual conductor bars into the inner and outer stator grooves along the helix, and connecting the conductor bars inserted into the inner and outer stator grooves at both ends of the conductor bars to form conductor loops.

[0065] According to one embodiment of the manufacturing method, the provision of the stator core includes manufacturing a laminated stator core, whereby individual stator laminations having recesses for forming stator grooves are laminated while being twisted relative to each other. In this way, the laminated stator core can be manufactured in a very economical way because the same mold can be used for all the stator laminations that are parallel or laminated. Thus, two adjacent stator laminations are slightly twisted relative to each other by a predetermined angle about the central axis such that the recesses overlap each other corresponding to a spiral path. The individual stator laminations having such a shape are advantageously manufactured by pressing or laser cutting individual laminations from an electromagnetic steel sheet.

[0066] According to another development of the method, the laminated stator core comprises an inner partial package and an outer partial package, all the stator laminations of the inner partial package are each formed in the same shape, all the stator laminations of the outer partial package are each formed in the same shape, and the stator laminations of the inner partial package forming the inner stator grooves and the stator laminations of the outer partial package forming the outer stator grooves are laminated such that they are twisted in opposite directions relative to each other. In this case, all the laminations of the inner partial package and the outer partial package can have the same shape, and the manufacturing process can be made very economical. Thus, the same cutting die can be used for all the parallel or laminated stator laminations of the inner partial package, and the same cutting die can be used for all the parallel or laminated stator laminations of the outer partial package.

[0067] Two adjacent stator thin plates of the inner part package are slightly twisted relative to each other by a predetermined angle in a first direction around a central axis, and two adjacent stator thin plates of the outer part package are slightly twisted relative to each other by a predetermined angle in a second direction around the central axis. In this way, the recesses of the stator thin plates of the inner part package and the recesses of the stator thin plates of the outer part package are arranged with opposite overlaps corresponding to opposite spiral paths. In this way, the opposite spiral paths of the stator grooves can be realized with less manufacturing effort.

[0068] According to another embodiment of the present method, the laminated stator core has a number of stator thin plates of different shapes, the recesses for the inner and outer stator grooves are provided in common stator thin plates respectively, and the pitch of the spiral is realized in particular by the relative continuous displacement of the inner and outer stator grooves for each stator thin plate using a flexible pressing or laser cutting process. In this case, the inner stator groove and the outer stator groove are provided in a single stator thin plate, and the spiral shape of the stator groove is achieved by relatively continuously moving the recesses relative to each other in the cutting process of the individual thin plates, for example, by a flexible pressing or laser cutting process. Thereby, fewer parts and fewer manufacturing steps are required, and the resulting stator thin plate or the entire stator core has the advantage of higher mechanical strength.

[0069] In another embodiment, the method further includes providing support means adapted to engage by fitting at an end of a conductor bar at at least one axial end for torque support, and engaging the support means at at least one axial end at a position axially offset with respect to the stator core by fitting at an end of the conductor bar.

[0070] According to one aspect, the stator thus manufactured further comprises a mechanically fixable base and a support device adapted to engage with the winding by fitting at at least one axial end for torque support, a step of fixing the support device to the base, and a step of providing a double rotor comprising an inner rotor and an outer rotor. The inner rotor and the outer rotor each have an annular base designed for magnetic flux propagation and a common central axis, a plurality of permanent magnets are fixed to the annular base respectively, a predetermined angular section of the annular base is associated with each permanent magnet, and the permanent magnets are formed and arranged on their respective bases such that the angular section is displaced circumferentially along the axial direction so that the permanent magnets generate a magnetic field that extends obliquely with respect to the central axis. The magnetic field of the inner rotor extends obliquely in a first direction towards a first rotational direction, and the magnetic field of the outer rotor extends obliquely in a second direction towards a second rotational direction. It can be used to implement a method for manufacturing a radial flux double rotor machine.

[0071] The above embodiments and other developments can be combined with each other in any desired way if useful. In particular, all features of the stator are transferable to the method of manufacturing the stator, and vice versa. Furthermore, all features of the stator can be transferred to the corresponding radial flux double rotor machine, as well as to an axle equipped with such a radial flux double rotor machine and / or a vehicle equipped with such an axle.

[0072] Further possible embodiments, further developments and equipment of the present invention also include combinations of features of the present invention described above or hereinafter with respect to examples of embodiments not explicitly mentioned. In particular, those skilled in the art will also add individual aspects as improvements or additions to each basic form of the present invention thereby.

Brief Description of the Drawings

[0073] The present invention will be described in more detail below with reference to examples of embodiments shown in the schematic diagrams of the drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11A

Figure 11B

Figure 11C

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Mode for Carrying Out the Invention

[0074] The accompanying drawings are intended to deepen a further understanding of the embodiments of the present invention. The drawings illustrate the embodiments and, in conjunction with the detailed description, serve to explain the principles and concepts of the present invention. Many other embodiments and the advantages mentioned will become apparent by referring to the drawings. The members in the drawings are not necessarily shown to scale with respect to each other.

[0075] In the figures of the drawings, the same members, features, and components having the same functions and the same effects are given the same reference numerals, respectively, unless otherwise specified.

[0076] FIG. 1 is an exploded perspective view showing a radial flux double rotor machine 10 including a stator 1 and a double rotor 100. The stator 1 and the double rotor 100 of the radial flux double rotor machine 10 have a common central axis M. The stator 1 is concentrically accommodated between the inner rotor 12 and the outer rotor 13 of the double rotor 100.

[0077] The stator 1 has a stator core 2 and a winding 3 with high torsional rigidity accommodated therein. Inside the stator 1 in the radial direction, the conductor bar 6 of the winding 3 with high torsional rigidity extends spirally in the first rotational direction. Outside the stator 1 in the radial direction, the conductor bar 6 of the winding 3 with high torsional rigidity extends spirally in the opposite second rotational direction.

[0078] The double rotor 100 includes an inner rotor 12 and an outer rotor 13. The inner rotor 12 and the outer rotor 13 each have an annular base 102, 103. The annular bases 102, 103 are designed for magnetic flux guidance and have a common central axis M. A plurality of permanent magnets 29 are attached to each of the annular bases 102, 103. A predetermined angular interval 32, 33 is assigned to each permanent magnet 29 in the cross section of the annular bases 102, 103. The predetermined angular intervals 32, 33 extend in an arc shape along the circumferential direction of the annular bases 102, 103.

[0079] The permanent magnets 29 are formed and arranged on the annular bases 102, 103 such that the predetermined angular intervals 32, 33 are displaced in the circumferential direction in the axial direction. Thereby, the permanent magnets 29 generate magnetic fields 34, 35 that extend obliquely with respect to the central axis M. The magnetic field 34 of the inner rotor 12 extends obliquely in the first direction toward the first rotational direction of the winding 3 with high torsional rigidity. The magnetic field 35 of the outer rotor 13 extends obliquely in the second direction toward the second rotational direction of the winding 3 with high torsional rigidity.

[0080] The magnetic fields 34, 35 of the permanent magnets 29 extending in opposite directions are shown in FIG. 1 by the arrows of the obliquely drawn broken lines. The magnetic field propagation lines of the magnetic fields 34, 35 extend obliquely in opposite directions on the permanent magnets 29 of the inner rotor 12 and the outer rotor 13 as shown in the drawing.

[0081] The design and arrangement of the permanent magnets 29 for displacing the angular intervals 32, 33 in the axial path are not limited to the embodiments shown here, and many modifications are possible.

[0082] Figure 2 is an exploded perspective view of the double rotor. The double rotor 100 has an inner rotor 12 and an outer rotor 13. The inner rotor 12 is concentrically housed within the outer rotor 13. A plurality of permanent magnets 29 are disposed on the inner circumferential surface of the annular base body 103 of the outer rotor 13.

[0083] A predetermined angular section 32 of the annular base body 103 is assigned to the permanent magnet 29 in the cross section. As shown in Figure 2, the angular section 32 is displaced circumferentially in the axial direction, and accordingly, the adjacent axial sections 30 of the permanent magnets are also displaced circumferentially in the axial direction.

[0084] The permanent magnet 29 is divided here as an example into a plurality of axial sections 30. However, in other embodiments, other designs and arrangements of the permanent magnet 29 for axially displacing the angular sections 32, 33 are also conceivable.

[0085] This geometric relationship is also provided on the outer circumferential surface of the annular base body 102 of the inner rotor 12. In other embodiments, the permanent magnet 29 can also be countersunk into the annular base bodies 102, 103 instead of or in addition to the illustrated arrangement of the permanent magnets on the surfaces of the inner rotor 12 and the outer rotor 13. Furthermore, the annular base bodies 102, 103 are made of solid material.

[0086] Figure 3 is a plan view showing the permanent magnet 29. The permanent magnet 29 is disposed on the annular base bodies 102, 103 (not shown) at an exemplary predetermined inclination angle ε with respect to the axial direction of the central axis M.

[0087] The illustrated permanent magnet 29 is divided into a plurality of axial sections 30 by way of example. Each axial section 30 is assigned angular sections 32, 33 (not shown) of the respective base body, and these angular sections 32, 33 are displaced by an attack angle θ around the central axis M with respect to the adjacent axial sections 30.

[0088] The total tilt angle φ resulting from the permanent magnets is caused by the attack angle θ, particularly multiples of the attack angle θ, due to the shape. When there are a predetermined number n of axial intervals 30 for each permanent magnet 29, the resulting total tilt angle φ is determined from the attack angle θ in the relationship φ = n * θ. Further, the predetermined tilt angle ε shown here as an example is formed as a function of the length of the radial flux double rotor machine 10. In other embodiments, the predetermined tilt angle may be defined differently from the illustration. In this regard, ε shown in FIG. 3 is merely illustrated as the angle projected onto the circumferential surface of the permanent magnet 29.

[0089] As shown in FIG. 3, in the illustrated embodiment, the axial intervals 30 are arranged such that the long sides are parallel to the central axis M. In this embodiment, the surfaces of the annular bases 102, 103 are optimally utilized. According to other embodiments, the edges of the axial intervals 30 may be arranged on the annular bases 102, 103 at an angle with respect to the central axis. For example, the edges of the axial intervals 30 may be aligned along a predetermined tilt angle ε. Further, in other embodiments, other orientations of the axial intervals 30 that result in the desired total tilt angle arrangement are possible on the surfaces of the annular bases 102, 103.

[0090] FIG. 4 is a schematic cross-sectional view of a part of the inner rotor 12 and the outer rotor 13 having the permanent magnets 29. The illustrated permanent magnets 29 are arranged axially one behind the other on the annular bases 102, 103 as shown in FIG. 3. Further, the resulting total tilt angle φ and attack angle θ about the central axis M (not shown) of the radial flux double rotor machine 10 are shown.

[0091] The circumferential displacement of each of the two axial sections 30 relative to each other is described by the angle of attack θ. Due to the concentric arrangement of the annular substrates 102, 103 and the arrangement of the axial sections 30 on each of the annular substrates 102, 103 being offset exclusively in the radial direction, the angles of attack θ of the permanent magnets 29 on the inner rotor 12 and the outer rotor 13 are of the same magnitude and in opposite directions to each other. This arrangement of the axial sections 30 is also decisive for the function of the double rotor 100.

[0092] As described above, the resulting total circumferential tilt angle φ is determined by the angle of attack θ of the axial section 30 and the number of axial sections 30. Furthermore, in the rectangular design of the axial section 30 of the permanent magnet 29 having a flat surface, a gap is provided between each axial section 30 and the inner or outer circumferential surface of the annular substrates 102, 103. This gap can be filled, for example, with a material connection medium when the axial section 30 of the permanent magnet 29 is integrally connected to the annular substrates 102, 103 by a material connection. The material connection can be realized, for example, by an appropriate adhesive. However, it should be noted that other mechanisms or methods for attachment are also possible, especially those without a gap between each axial section 30 and the annular substrates 102, 103. For example, local recesses of the rotor for gap compensation are alternatively or additionally conceivable. Furthermore, in other embodiments, the inner and outer permanent magnets can preferably be of the same size or different sizes, as shown here, in order to cover the same angular interval aligned in the radial direction.

[0093] FIG. 5 is a plan view of the parallelogram-shaped permanent magnet 29. The shape of the axial direction section 30 or the permanent magnet 29 can also deviate from the rectangle shown in FIG. 3 as shown in FIG. 5. The illustrated permanent magnet 29 has a parallelogram shape, and the diagonal edge 31 of the permanent magnet 29 is inclined at a predetermined inclination angle ε with respect to the axial direction of the central axis M. In this regard, there is a total inclination angle φ as a result of being identically formed in the circumferential direction around the central axis M of the permanent magnet 29. When using the parallelogram-shaped permanent magnet 29, the surfaces of the annular substrates 102, 103 (not shown) can be optimally utilized, and there is no protrusion or surface exposure of the permanent magnet 29.

[0094] FIG. 6 is a schematic cross-sectional view showing a partial cross-section of the inner rotor 12 and the outer rotor 13 provided with the parallelogram-shaped permanent magnet 29. Similar to FIG. 4, the resulting total inclination angle φ in the circumferential direction around the central axis M can be seen. The resulting total inclination angle φ represents the circumferential sweep angle generated by the diagonal edge 31 (not shown) of each permanent magnet 29. The problems regarding the formation of the gap in the inner rotor 12 and the outer rotor 13 described with reference to FIG. 4 can be solved in the same manner for the illustrated parallelogram-shaped permanent magnet 29. The arrangement of the permanent magnets 29 on the annular substrates 102, 103 with respect to each other is provided as a function of the resulting total inclination angle φ. The total inclination angle φ with respect to the circumferential direction is equal in magnitude but in the opposite direction for the illustrated permanent magnets 29 on the inner rotor 12 and the outer rotor 13 because the rotational directions are opposite.

[0095] In the illustrated embodiment, the inner and outer permanent magnets 29 are of different sizes so as to cover equal angular intervals in the radial direction. However, in other embodiments, for example, in order to reduce costs as part of an integrated strategy, the inner and outer permanent magnets can also be of the same size.

[0096] FIG. 7 is a perspective view of the winding 3. The winding 3 is composed of conductor bars 6 that extend spirally along the central axis M. For this reason, the conductor bars 6 are not only arranged to correspond and combine with each other, but are also twisted with respect to each other along a spiral path.

[0097] The sweep angle β of the conductor bar 6 specifies the angle between the start end and the end end of the conductor bar 6 with respect to the central axis M. The pitch of the helix of the conductor bar 6 is equal to the pitch of the helix of the stator grooves 19, 20, but the conductor bar 6 is formed longer than the stator grooves. In order to characterize the geometric conditions, the ratio of the respective sweep angles α, β can be formed, which is also called the pole coverage factor. In order to provide an optimum between the magnetic losses and torque utilization of the radial flux double rotor machine, this ratio (pole coverage factor) is preferably in the range between 0.6 and 0.75.

[0098] The opposite twisting and rotation of the radially inner layer 15 and the radially outer layer 14 of the conductor bar 6 can also be seen here. The twist is such that the cross-section with respect to the radial line passing through the center of the conductor bar is always the same at any point on the conductor bar, and is also called a 2.5D shape. Therefore, the ends of the conductor bars 6 of the inner layer 15 and the outer layer 14 are arranged to overlap each other in the same orientation. Therefore, the conductor bars 6 of the radially inner layer 15 and the radially outer layer 14 can be conductively connected in a simple manner, here by way of example, via radially extending conductor bar pieces 17 welded to the conductor bar 6.

[0099] It should be noted that the winding shown here is not manufactured individually by itself, but is always manufactured in combination with the stator core 2 as described in more detail with reference to FIG. 23.

[0100] The winding 3 has a radially inner layer 15 of conductor bars 6 arranged spirally in the radially inner part (not shown) of the stator 1, and a radially outer layer 14 of conductor bars 6 arranged spirally in the opposite direction in the radially outer part of the stator 1.

[0101] FIG. 8 is a perspective view of the stator core 2. The stator core 2 includes a laminated stator core 18 having a winding path corresponding to the spirally extending stator grooves 19, 20. The inner stator groove 20 in the radially inner part of the stator 1 (not shown) extends along the first rotation direction, and the outer stator groove 19 in the radially outer part of the stator 1 extends along the second rotation direction, extending in opposite directions to each other.

[0102] The laminated stator core 18 includes an inner partial package 23 having a radially inner stator groove 20 and an outer partial package 24 having a radially outer stator groove 19. The stator thin plates 22 of the inner partial package 23 are each designed to have the same shape, and the stator thin plates 21 of the outer partial package 24 are each designed to have the same shape. The stator thin plates 22 of the inner partial package 23 are laminated according to the first rotation direction of the conductor bar 6 (not shown), and the stator thin plates 21 of the outer partial package 24 are laminated according to the second rotation direction of the conductor bar 6, being twisted in opposite directions to each other by a predetermined twist angle γ around the central axis M. The twist angle γ represents the circumferential angle with respect to the central axis M between both axial ends of the laminated stator core 18 resulting from the twist of the individual stator thin plates 21, 22 with respect to each other.

[0103] In a specific embodiment, the sweep angle α of the stator groove is the same as the twist angle γ. Since the distortion of the magnetic field does not completely follow the path of the stator groove, the resulting total circumferential tilt angle φ must be smaller than the twist angle γ. Therefore, the resulting total circumferential tilt angle φ of the permanent magnet 29 of the inner rotor 12 (not shown) is in the range of 20% to 40% of the twist angle γ of the stator thin plate 22 of the inner partial package 23, and / or the resulting total circumferential tilt angle φ of the permanent magnet 29 of the outer rotor 13 is in the range of 20% to 40% of the twist angle γ of the stator thin plate 21 of the outer partial package 24. When the resulting total circumferential tilt angle φ coincides with the twist angle γ as described above, the maximum increase in torque can be obtained.

[0104] FIG. 9 is a cross-sectional view of the radial flux double rotor machine 10. In the illustrated arcuate cross-section of the radial flux double-rotor machine 10, conductor bars 6, permanent magnets 29, stator 1, inner rotor 12, outer rotor 13, and annular substrates 102, 103 are shown. Further, the tangential flux in the inner rotor 12 and the outer rotor 13 and the radial flux in the stator 1 are also shown. In the illustrated embodiment, the stator 1 is formed "yoke-less". Thus, although the stator yoke 38 extends between the conductor bars 6, it merely serves to mechanically connect the laminated stator core 18 (not shown) of the stator 1. As shown in FIG. 9, the stator yoke 38 is within the functionally related magnetic flux. However, in the illustrated embodiment of the radial flux double-rotor machine 10, the tangential flux decreases at the axial ends of the radial flux double-rotor machine 10. This has an adverse effect on the efficiency of the radial flux double-rotor machine 10 and correspondingly causes an undesirable reduction in torque.

[0105] FIG. 10 is a cross-sectional view of a radial flux double-rotor machine 10 according to another embodiment. The embodiment of the radial flux double-rotor machine 10 shown in FIG. 10 has a significantly thicker stator yoke 38 (not to scale) compared to the embodiment shown in FIG. 9. The stator yoke 38 is explained by the depicted radial yoke thickness 36.

[0106] The permanent magnets 29 of the inner rotor 12 and the outer rotor 13 each have a predetermined tangential direction width 37. In a particularly advantageous embodiment, the stator core 2 has a radial yoke thickness 36 within the range of 10% to 20% of the tangential direction width 37 of the permanent magnet 29. Thus, tangential flux propagation can be supported at both axial ends of the radial flux double-rotor machine 10.

[0107] In an embodiment provided with a permanent magnet 29 having a parallelogram shape, the cross-section of the permanent magnet 29 is decisive for the relationship between the tangential direction width 37 and the radial yoke thickness 36 of the permanent magnet 29.

[0108] Figures 11A to 11C are cross-sectional views of the radial flux double rotor machine 10 showing magnetic field distortion. The three cross-sectional views (left in Fig. 11A, center in Fig. 11B, right in Fig. 11C) each show the axial position within the radial flux double rotor machine 10. The left cross-sectional view shows the front end of the radial flux double rotor machine 10, the center cross-sectional view shows the axial center, and the right cross-sectional view shows the rear end.

[0109] Here, the radial flux double rotor machine 10 includes a single-shaped permanent magnet 29 arranged axially. As seen in Fig. 11, only the center cross-sectional view of the radial flux double rotor machine 10 contains a uniform magnetic field, and the magnetic field lines in the stator 1 extend solely in the radial direction. In the left and right cross-sectional views of the radial flux double rotor machine 10, magnetic field distortion occurs as shown in the drawing. In the left and right cross-sectional views, the respective magnetic field lines are distorted correspondingly in the left and right cross-sectional views, especially within their respective stators.

[0110] Furthermore, the displacement of the conductor bars 6 across the axial positions (front end, axial center, rear end) of the radial flux double rotor machine 10 is clear from the three cross-sectional views. Only in the central figure are the conductor bars 6 of the same strands (U, V, W) and the same current direction (+, -) arranged vertically. As a result, the magnetic field shows its maximum amplitude only at the axial center of the radial flux double rotor machine 10. Due to the basic geometric relationship between the conductor bars 6 and the permanent magnet 29, the amplitude of the magnetic field decreases towards both axial ends (left and right cross-sectional views) of the radial flux double rotor machine 10. As a result, magnetic field distortion occurs, and since the permanent magnets of the rotor are not in the optimal position for torque generation, the torque decreases. This is offset by the arrangement and design of the permanent magnets 29 on the respective annular substrates 102, 103 along the axial direction as described with reference to Figs. 1 to 6. The permanent magnets 29 generate magnetic fields 34, 35 that extend obliquely with respect to the central axis M and are optimally arranged within the range of magnetic field distortion.

[0111] Fig. 12 shows a schematic longitudinal section of the stator 1. This is a schematic view of a radial flux double rotor machine 10 (see Fig. 13), in particular of a stator 1 for a wheel hub motor. The stator comprises a stator core 2, windings 3, and a support device 5. The stator core 2, the windings 3, and the support device 5 are designed to be rotationally symmetric about the illustrated central axis M.

[0112] The windings 3 are self-supporting to support the torque of the stator 1 and project beyond the stator core 2 at at least one axial end 4. The support device 5 is arranged axially offset with respect to the stator core 2 and is connected to the windings 3 by fitting at at least one axial end 4 for torque support. In this way, the torque applied to the stator core 2 during operation of the radial flux double rotor machine 10 can be supported by the self-supporting windings 3 in the support device 5.

[0113] The windings include a conductor material with low electrical resistance, preferably copper. The stator core 2 is preferably composed of a soft magnetic material for magnetic flux propagation. The support device preferably includes a heat conducting material, for example, an aluminum alloy. Of course, the windings 3 are electrically insulated.

[0114] Fig. 13 shows a schematic longitudinal section of the radial flux double rotor machine 10. This is also a purely exemplary schematic view. Thus, the radial flux double rotor machine 10 has, in addition to the stator 1 shown in Fig. 12, a mechanically fixed base 11, a first rotor 12, and a second rotor 13. The stator core 2, the windings 3, the support device 5, the base 11, the first rotor 12, and the second rotor 13 are likewise designed to be rotationally symmetric about the illustrated central axis M.

[0115] The winding 3 is self-supporting to support the torque of the stator 1, projects beyond the stator core 2 at at least one axial end 4, and is supported on the base 11 via a support device 5. For this reason, the support device 5 is arranged axially offset with respect to the stator core 2 and is connected to the winding 3 by fitting at at least one axial end 4 for torque support. The support device 5 is fixed to the base such that the torque is supported on the base 11 via the support device 5.

[0116] The first rotor 12 is arranged radially inside the stator core 2, and the second rotor 13 is arranged radially outside the stator core 2. The base 11 can be designed, for example, as the housing of a machine. In this case, in a purely exemplary manner, it has an L-shaped structure with two legs 7, 8. The figure is not to be understood as comprehensive, rather the base may also have further components and / or structural parts. The first leg 8 extends substantially radially, and the second leg 7 extends substantially axially at the position furthest from the central axis M.

[0117] Purely schematically, the support device 5 is shown as a single part extending radially, but it may be provided by a plurality of parts and / or in other shapes designed to engage with the winding 3 by fitting. The overlap between the illustrated winding 3 and the base 11 is due to the purely illustrated schematic diagram and does not mean a direct connection. The winding 3 is preferably connected to the base 11 via the support device 5 for torque support.

[0118] FIG. 14 is an exploded perspective view of a radial flux double rotor machine 10 according to an embodiment. The radial flux double rotor machine 10 includes a first rotor 12, a second rotor 13, and a base 11 in addition to the components of the stator 1. The first rotor 12 is arranged radially inside the stator core 2, and the second rotor 13 is arranged radially outside the stator core 2. The rotors 12, 13 are preferably made of a soft magnetic solid material, and permanent magnets, so-called surface magnets, are attached as magnetic poles to the respective surfaces facing the stator core. The permanent magnets 29 are arranged as shown in FIGS. 1 and 2.

[0119] The base 11 is here only schematically shown for the sake of clarity. As already described in the description of FIG. 13, the base 11 is fixed in a state of being attached to the support device 5. The base 11 is mechanically fixed to a reference system, for example, a support part of an axle.

[0120] FIG. 15 is an exploded perspective view of the stator 1 according to another embodiment. The stator 1 includes a winding 3, a stator core 2, and a support device 5, and here, advantageous exemplary embodiments of these components are shown in more detail by the perspective drawing method.

[0121] The winding 3 is composed of an inner layer and an outer layer having a plurality of conductor bars 6 connected to each other in a bar shape. The conductor bars 6 of the inner layer and the outer layer are arranged spirally in opposite directions to each other, and at both ends of the conductor bar, they are materially coupled to the radial conductor bar pieces 17 connecting the inner layer and the outer layer.

[0122] The thicknesses of the inner layer and the outer layer respectively correspond to the thickness of the conductor bar 6. That is, it means that the winding 3 is formed by a single conductor layer forming conductor loops having a relatively large cross-section in the form of the conductor bar 6 respectively.

[0123] The bar structure formed by the plurality of conductor bars increases the torsional rigidity of the winding, and thereby self-support is realized for torque support. Accordingly, the plurality of conductor bars 6 form a wavy winding strand and are interconnected by suitable interconnection means known to those skilled in the art, such as delta connection, star connection, etc., and thus will not be described further herein, to form a rotating magnetic field generating winding having any number of strands.

[0124] In the illustrated embodiment, the stator core 2 and the support device 5 are each composed of, as an example, two parts. For the assembly of the stator 1, the winding 3, the stator core 2, and the support device 5 are arranged concentrically with each other. After assembly, the components are aligned coaxially with each other along a common central axis M. The two-part support device 5 illustrated here is arranged axially offset with respect to the other components and forms the innermost and outermost components of the stator 1. These are an inner ring and an outer ring, each designed to have a groove for engaging with the conductor bar by fitting.

[0125] The exemplary two-part stator core 2 here is formed by two laminated stator cores 18 twisted spirally with respect to each other, which will be described in more detail with reference to FIG. 19. In other embodiments, the stator core 2 and the support device 5 may each be designed as a single piece or by more than two parts.

[0126] FIG. 16 is an exploded perspective view of a radial flux double rotor machine 10 according to another embodiment. The radial flux double rotor machine 10 here has substantially the same components as described with reference to FIGS. 15 and 4. Shown on the left side of the figure in the assembled state are the stator core 2, the winding 3, the first rotor 12, and the second rotor 13.

[0127] The support device 5 shown on the right side is also formed in two parts, and the configurations of the respective annular inner support member 27 and outer support member 28 are different. The support members 27, 28 are provided here with support grooves 26. These grooves are provided on the inner circumference of the outer support member 28 and the outer circumference of the inner support member 27 in order to engage with the conductor bars 6 of the winding 3.

[0128] For this purpose, the support grooves 26 are designed to be angled axially according to the spiral path or its pitch of the conductor bar so as to be able to engage with the conductor bars 6 of the winding 3.

[0129] The support members 27, 28 are preferably made of a conductive metal, particularly preferably an aluminum alloy. Due to the two-part design of the support members 27, 28, it is possible to easily access the support grooves 26 for mechanical or machining processes during manufacturing.

[0130] The inner support member 27 and the outer support member 28 each have a plurality of holes 9 for attachment to the base 11 in the circumferential direction. Exemplarily, the holes 9 are evenly arranged on the circumference along the pitch circle here. The individual holes 9 are located slightly outside the body of the support member, and the support members 27, 28 thus form a star shape on the circumference facing away from the winding respectively. Of course, other distributions of the holes 9 are also conceivable, and other types of fastening means for connection to the base 11 are also conceivable.

[0131] FIG. 17 is a perspective view of the radially-flux double-rotor machine 10 according to FIG. 16 in the mounted state. The support device 5 is fastened, for example, by means of the holes 9 to a machine housing (not shown) as the base 11, thereby transmitting torque to the mechanically fixed part of the radially-flux double-rotor machine 10. In this way, the torque generated by the radially-flux double-rotor machine 10 can be effectively supported. The support device 5 is fixed by corresponding fixing means (not shown), for example, by screws.

[0132] The conductor bars 6 of the winding 3 extend axially to both sides up to the outside of the stator core 2 and the first rotor 12 and the second rotor 13. The conductor bars 6 arranged in a spiral in the radially inner layer and the outer layer are connected to each other on the outside of the stator core 2, respectively.

[0133] The support members 27, 28 are shown here in a state of engaging with the conductor bars 6 of the winding 3. It can be seen that the conductor bars 6 are arranged in the respective support grooves 26 and all the conductor bars are joined by fitting into the support device. Therefore, the torque supported via the winding 3 can be supported by the base 11 fixed to the hole 9 via the support device 5.

[0134] FIG. 18 is a longitudinal cross-sectional perspective view of a radial flux double rotor machine 10 according to another embodiment. This embodiment is basically the same as the assembled radial flux double rotor machine 10 shown in FIG. 14, and its components will be described in more detail below.

[0135] The stator core 2 has an inner partial package 23 and an outer partial package 24. The partial packages 23, 24 extend annularly between the first rotor 12 and the second rotor 13. Based on the cross-sectional view, it is also possible to see the inner layer 15 and the outer layer 14 of the conductor bars 6 extending inside the partial packages 23, 24.

[0136] The illustrated radial flux double rotor machine 10 is a so-called "yokeless" design in which the yoke between two teeth does not exist within the functionally related magnetic flux. Thus, although the stator yoke 38 extends between the conductor bars 6, it merely serves to mechanically hold together the laminated stator core 18. The radial yoke thickness can correspondingly be designed to be thin, and in the illustrated embodiment, it is illustratively about 10% of the total stator thickness in the radial direction. Furthermore, the relatively small yoke thickness reduces the undesirable leakage flux in the yoke. In other embodiments, the radial yoke thickness can be less than 30%, preferably less than 20%, and particularly preferably less than 10% of the total stator thickness in the radial direction for this purpose.

[0137] Also, here, the support device 5 has an inner support member 27 and an outer support member 28. The support members 27, 28 are clearly axially offset from the stator 5 and the rotors 12, 13 here. Furthermore, at least a cross-section of the engagement by the fitting of the support members 27, 28 with the conductor bars 6 of the inner layer 15 and the outer layer 14 can be seen.

[0138] Furthermore, here, it can be clearly seen that the conductor bars 6 of the inner layer 15 and the outer layer 14 are connected at both ends 16 of the conductor bar by conductor bar pieces 17 arranged in the radial direction. This connection is preferably manufactured as a material connection by, for example, laser welding.

[0139] Furthermore, the magnets on the surfaces of the rotors 12, 13 can also be seen in this cross-section. The first rotor 12 has a plurality of permanent magnets on its outer peripheral surface. The second rotor 13 has a plurality of permanent magnets on its inner peripheral surface.

[0140] A particularly advantageous embodiment is provided when the rotor is made of a soft magnetic solid material and manufactured with surface-mounted permanent magnets. In this design, the rotor can be manufactured very inexpensively and high efficiency can be achieved.

[0141] FIG. 19 is an exploded perspective view of the stacked stator core 18 of the stator core 2. As already described, the stacked stator core 18 of the stator core 2 has an inner partial package 23 and an outer partial package 24. This is stacked in a rotated manner with respect to each other and uses the same inner stator thin plate 21 and outer stator thin plate 22 provided with recesses at the same positions, which helps to simplify the manufacture of the stator grooves 19 that are rotated in opposite directions with respect to each other.

[0142] In other embodiments, the stator thin plates can also be manufactured as a single part such that a plurality of different-shaped stator thin plates having recesses in different arrangements are provided and stacked in the order required to form the stator grooves. In still other embodiments, a completely integrated stator core 2 is also conceivable, which can be manufactured additionally, for example.

[0143] In the illustrated two-part configuration, the inner diameter of the outer partial package 24 is approximately equal to the outer diameter of the inner partial package 23. Thereby, the inner partial package 23 can be coaxially arranged within the outer partial package 24.

[0144] The partial packages 23, 24 are formed by stacking one of the individual annular stator thin plates 21, 22 on top of the other. The stator thin plate 21 of the outer partial package 24 is manufactured to have recesses distributed on the outer circumference in order to form the outer stator groove 19. The stator thin plate 22 of the inner partial package 23 is manufactured to have recesses distributed on the inner circumference in order to form the inner stator groove 20. For example, manufacturing these stator thin plates by pressing is advantageous due to the edge quality and very low manufacturing costs.

[0145] The inner stator groove 20 and the outer stator groove 19 depict spirals that extend in opposite directions with the same pitch and are characterized by the indicated sweep angle α of the stator grooves. The sweep angle α of the stator grooves can be defined from the angle formed by the positions of the same stator slot on one axial side and the other axial side of the stator core 2 with respect to the central axis M.

[0146] The stator grooves 19, 20 are here, by way of example, designed as T-grooves having rectangular recesses with narrowed openings. These are provided in particular for receiving conductor bars having a rectangular cross-section by fitting. Of course, the shape of the recess or the stator groove can be adapted to the shape of the conductor. Also, for this purpose, other cross-sectional shapes are conceivable.

[0147] Figure 20 is a schematic longitudinal sectional view of the stator grooves 19, 20. The usable or continuous gap width a of the stator grooves 19, 20 within the laminated stator core 18 is substantially equal to the width of the conductor bar 6 accommodated within the stator core 2. The stator thin plates 21, 22 have straight, in particular punched, edges. Due to the offset of the thin plates relative to each other, the width b of the recess provided for the stator grooves 19, 20 is larger than the width d of the conductor bar 6 by an amount predetermined by the pitch δ of the spiral shape of the path and the thickness t of the thin plates.

[0148] In Figure 20, the conductor bar 6 is schematically depicted in dashed lines within the stator grooves 19, 20. The continuous gap width a of the stator grooves 19, 20 is slightly larger than the width d of the conductor bar 6 to provide a clearance fit, and the width b of the recess of the stator thin plates 21, 22 is considerably larger than the gap width a.

[0149] In the case of straight, for example punched, edges of the thin plates, the plate thickness t and the attack angle (set angle) δ of the pitch of the groove path are factors that significantly influence the difference between the width b of the recess and the gap width a of the usable passage within the groove. This difference occurs because on the one hand the pitch angle and on the other hand the stepped steps of the laminated core have to be corrected.

[0150] In the case of the limit of an infinitely thin plate, i.e., when purely considering the pitch angle δ of the conductor bar, the minimum size of the width b of the recess is as follows. b = 1 / cos(δ) * d On the one hand, the actual plate thickness is additionally corrected, and on the other hand, to provide a clearance fit that allows the insertion of the conductor bar, the width b of the recess is actually provided to be even larger.

[0151] The width b of the recess shown in FIG. 20 forms a predetermined clearance fit with the width d of the conductor bar 6 inserted into the stator grooves 19, 20, where the gap width a between the stator grooves 19, 20, which is reduced by the offset between the recesses of the stator thin plates, but nevertheless, the contact is dimensioned to be close enough to provide uniform power transmission or torque support distributed between the laminated stator core and the winding. Such dimensioning is realized, in particular, by the fact that on the one hand, each stator thin plate is formed with an equally high edge quality and rotated with an equal offset, and on the other hand, only a single conductor bar 6 is arranged in each stator groove 19, 20 and its dimensions are constant.

[0152] In particular, in the illustrated embodiment, the conductor bar 6 is, for example, a bar with a rectangular cross-section having an edge length or width in the range of 2 mm to 6 mm, particularly in the range of 3 mm to 5 mm. Preferably, it may have a rectangular cross-sectional shape of 5 mm × 3 mm.

[0153] FIG. 21 is a plan view of the winding 3. In this figure, it can be clearly confirmed the exact radial alignment of the conductor bars at each point of the spiral path aligned in the region of the central axis M in the illustrated plan view. The ends 16 of the conductor bars each form a connection point between the radially inner layer 15 and the radially outer layer 14.

[0154] In the illustrated embodiment, the winding, as an example, has a total of twelve terminal contacts 31. In the case of a three-phase connection, preferably, a three-phase operation is provided. However, the winding can be adapted to other interconnections by methods known to those skilled in the art in order to form a rotating magnetic field generating winding of any number of phases.

[0155] FIG. 22 is a perspective view showing a FEM simulation of the loaded winding 3. Some simplifications were made for the simulation, but this is basically the winding shape shown in FIG. 7. The scale shown is related to the stress in the winding. For example, when the cross-sectional shape of the conductor bar 6 is a rectangle of 5 mm × 3 mm, the scale is from 0 MPa to 30 MPa.

[0156] In this example, the ends of the conductor bars are defined by the sweep angle β>0 of the conductor bars, that is, they are arranged and formed in a spiral shape or are shaped in a correspondingly twisted manner. At the axial ends where the support device engages, the maximum torque of the radial flux double-rotor machine 10 of corresponding dimensions is depicted as shown by the thick arrows. For example, when the cross-sectional shape of the conductor bar 6 is a rectangle of 5 mm × 3 mm, the maximum torque can be about 5000 Nm.

[0157] It can be seen that due to the spiral shape, the stress in the winding is very evenly distributed. Despite being exaggerated, hardly any deformation is visible. This design can significantly reduce the stress peaks and thus the deformation.

[0158] Due to a structure such as a bar structure, the winding 3 can absorb high torque in a self-supporting manner without causing unacceptable large deformations and / or stress states when fixing the axially accessible winding ends. This is mainly due to the fact that the conductor bars 6 of the bar structure absorb tensile and compressive stresses especially when receiving tangential forces. Therefore, compared with a design using straight conductors parallel to the axis, the mechanical stress can be significantly reduced.

[0159] FIG. 23 is a perspective view of a comparison model of a straight-line design, showing the axial path of the conductor bar 6 under load. Comparing with FIG. 22, it can be seen that due to the straight-line design and the axial path of the conductor bar, the stress path concentrates on the side shown on the left side of FIG. 23, and on the side shown on the right side of FIG. 23, a large deformation of the conductor bar occurs due to locally high stress with large deformation. Here, the same stress scale and the same deformation expansion as in FIG. 22 are set, showing the influence of the difference in structural arrangement on the torsional rigidity.

[0160] FIG. 24 is a flowchart of a manufacturing method of the stator 1. This method includes a first step S1 of providing a stator core 2 having stator grooves 19 on the radially outer side each depicting a helix and stator grooves 20 on the radially inner side each depicting a helix with opposite winding directions. Another step S2 relates to the insertion of individual conductor bars 6 along the helix passing through the inner and outer stator grooves 19, 20. The conductor bar is inserted axially in particular. Further, a step S3 of connecting the conductor bars 6 inserted into the inner and outer stator grooves at the conductor bar end portions 16 to form a conductor loop is provided.

[0161] As described above, the present invention has been fully described with reference to the preferred embodiments, but the present invention is not limited thereto, and various modifications are possible.

Explanation of Reference Numerals

[0162] 1 Stator 2 Stator Core 3 Winding 4 Axial End 5 Support Device 6 Conductor Bar 7 Second Leg 8 First Leg 9 Hole 10 Radial Flux Double Rotor Machine 11 Base 12 First Rotor / Inner Rotor 13 Second Rotor / Outer Rotor 14 Radially Outer Layer 15 Radial inner layer 16 Conductor bar end 17 Conductor bar piece 18 Stacked stator core 19, 20 Stator groove 21, 22 Stator thin plate 23 Inner part package 24 Outer part package 25 Support member 26 Support groove 27 Inner support member 28 Outer support member 29 Permanent magnet 30 Axial interval 31 Oblique edge 32, 33 Predetermined angle interval 34, 35 Magnetic field 36 Yoke thickness 37 Tangential direction width 38 Stator yoke 100 Double rotor 102, 103 Annular substrate α Sweeping angle of stator groove β Sweeping angle of conductor bar γ Twisting angle δ Pitch angle ε Predetermined inclination angle θ Attack angle φ Total inclination angle a Gap width b Width of recess d Width of conductor bar M Central axis t Plate thickness

Claims

1. A stator (1) having a stator core (2) and a winding (3) with high torsional rigidity housed therein, wherein a conductor bar (6) of the winding (3) with high torsional rigidity extends spirally in a first rotational direction on the inner radial side of the stator (1), and the conductor bar (6) of the winding (3) with high torsional rigidity extends spirally in a second rotational direction opposite thereto on the outer radial side of the stator (1), and a stator (1); A double rotor (100) having an inner rotor (12) and an outer rotor (13), wherein the inner rotor (12) and the outer rotor (13) each have a common central axis (M) with an annular substrate (102, 103) designed for magnetic flux propagation, and a double rotor (100); A plurality of permanent magnets (29) are respectively fixed to the annular substrates (102, 103), and a predetermined angular section (32, 33) of the annular substrates (102, 103) is associated with each of the permanent magnets (29); The permanent magnets (29) are formed and arranged on each of the annular substrates (102, 103) such that the predetermined angular section (32, 33) shifts circumferentially along the axial direction, thereby generating a magnetic field (34, 35) in which the permanent magnets (29) extend obliquely with respect to the central axis (M), the magnetic field (34) of the inner rotor (12) extends obliquely in a first direction toward the first rotational direction, and the magnetic field (35) of the outer rotor (13) extends obliquely in a second direction toward the second rotational direction. In particular, a radial flux double rotor machine (10) for driving a wheel hub.

2. The radial flux double rotor machine (10) according to claim 1, wherein the annular substrates (102, 103) are made of a solid material.

3. The radial flux double rotor machine (10) according to claim 1 or claim 2, wherein the permanent magnets (29) are arranged on the annular substrates (102, 103) at a predetermined inclination angle (ε) with respect to the axial direction of the central axis (M).

4. The permanent magnets (29) are each formed by being divided into a plurality of axial direction sections (30), and to each of the axial direction sections (30), angular sections (32, 33) are assigned which are offset by an attack angle (θ) about the central axis (M) with respect to an adjacent axial direction section (30), and as a result, a total circumferential inclination angle (φ) is produced from the attack angle (θ). The radial flux double rotor machine (10) according to any one of claims 1 to 3.

5. For a predetermined number n of the axial direction sections (30) for each of the permanent magnets (29), the resulting total circumferential inclination angle (φ) is obtained from the attack angle (θ) in a relationship of φ = n * θ. The radial flux double rotor machine (10) according to claim 4.

6. The permanent magnets (29) are each divided into two of the axial direction sections (30). The radial flux double rotor machine (10) according to claim 4 or claim 5.

7. The permanent magnets (29) are aligned along a predetermined inclination angle (ε) by edges. The radial flux double rotor machine (10) according to claim 3.

8. The permanent magnets (29) have an oblique parallelogram shape. The radial flux double rotor machine (10) according to claim 7.

9. The winding (3) has an inner layer (15) in the radial direction of the conductor bars (6) arranged spirally inside the stator (1) in the radial direction, and an outer layer (14) in the radial direction of the conductor bars (6) arranged spirally in the opposite direction outside the stator (1) in the radial direction. The radial flux double rotor machine (10) according to any one of claims 1 to 8.

10. The stator core (2) includes a laminated stator core (18) having stator grooves (19, 20) extending spirally corresponding to the winding paths. The inner stator groove (20) in the inner radial portion of the stator (1) extends along the first rotation direction, and the outer stator grooves (19) in the outer radial portion of the stator (1) extend in opposite directions along the second rotation direction. The radial flux double rotor machine (10) according to any one of claims 1 to 9.

11. The laminated stator core (18) includes an inner partial package (23) having an inner stator groove (20) on the radially inner side and an outer partial package (24) having an outer stator groove (19) on the radially outer side. The stator thin plates (22) of the inner partial package (23) are designed in the same shape respectively, and the stator thin plates (21) of the outer partial package (24) are designed in the same shape respectively. The stator thin plates (22) of the inner partial package (23) are laminated so as to be twisted in opposite directions by a predetermined twist angle (γ) around the central axis (M) according to the first rotation direction of the conductor bar (6), and the stator thin plates (21) of the outer partial package (24) are laminated so as to be twisted in opposite directions by a predetermined twist angle (γ) around the central axis (M) according to the second rotation direction of the conductor bar (6). The radial flux double-rotor machine (10) according to claim 10.

12. The resulting total inclination angle (φ) in the circumferential direction of the permanent magnets (29) of the inner rotor (12) is in the range of 20% to 40%, preferably 25% to 35%, particularly preferably 28% to 32% of the twist angle (γ) of the stator thin plates (22) of the inner partial package (23), and / or the resulting total inclination angle (φ) in the circumferential direction of the permanent magnets (29) of the outer rotor (13) is in the range of 20% to 40%, preferably 25% to 35%, particularly preferably 28% to 32% of the twist angle (γ) of the stator thin plates (21) of the outer partial package (24). The radial flux double-rotor machine (10) according to claim 11.

13. The permanent magnets (29) of the inner rotor (12) and the outer rotor (13) have a magnetic pole width (37) in a predetermined tangential direction, and the stator core (2) has a radial yoke thickness (36) in the range of 5% to 25%, preferably 10% to 20%, particularly preferably 12.5% to 17.5% of the magnetic pole width in the tangential direction. The radial flux double-rotor machine (10) according to any one of claims 1 to 12.

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