Radial magnetic 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 field excitation magnets (in the case of a permanent magnet synchronous machine PSM) or conductor materials (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, these machines have not been mass-produced so far 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 allows the use of single-tooth windings, which has corresponding disadvantages in terms of noise excitation.

[0004] In contrast, in the case of radial flux double rotor machines, established and mass-production-appropriate manufacturing methods can be used for the windings and laminated core. However, a significant technical challenge remains in supporting the torque generated in the stator core. Due to the rotating components on the inside and outside, the laminated stator core cannot be mounted to a fixed housing (e.g., press-fit, fasten, or bond) as in the usual case. Therefore, the torque is directed to and supported at both axial ends of the laminated stator core or stator windings. Various approaches have been proposed in the prior art in this regard, but all of them have considerable disadvantages in terms of function and / or cost.

[0005] European Patent No. 1879283 discloses a method for designing stator windings as so-called yoke windings. In this case, an annular stacked stator core has grooves in its inner and outer diameters, with a tangentially acting magnetic return path (also called a stator yoke) between them. The forward and return conductors of each winding strand are guided into radially overlapping grooves 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 axial screw connections (for example, as described in Japanese Patent Application Publication No. 2018-082600). The axial pressure of the screws ensures both torsional rigidity of the stacked core and torque support at the axial ends. The north and south poles of the rotor magnetic field are positioned opposite each other. A drawback of this concept is that the magnetic flux must be fully propagated through the return yoke between the stator grooves. This increases the weight of the stacked stator core and significantly increases iron loss.

[0006] The magnetic field lines of both rotors are closed via magnetic return paths within the stacked stator core, where iron losses occur. Furthermore, all individual coils of the yoke winding must be connected in parallel or series in the winding head region, resulting in space competition with the torque support. However, the windings wound on the yoke allow for direct mechanical contact with the stacked stator core.

[0007] Significant weight and loss reductions can be achieved if the magnetization direction of magnets extending radially in the same direction from one point to another is the same as the current direction of conductors extending one over another within a slot. In this case, the magnetic return path in the stator can be omitted, creating a so-called "yokeless" double-rotor machine with distributed windings. The magnetic field lines are closed on the rotor. Because the magnetic return path in the stator is unnecessary, weight and iron losses are very low in such machines. However, distributed windings do not allow direct mechanical contact of the stacked stator cores for torque support. For example, International Publication No. 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, for example, as described in German Patent Publication No. 102010055030 or U.S. Patent No. 7557486. The problem here is that metals, which are electrically and / or magnetically conductors, are not allowed to protrude into the magnetic flux propagation region, or can only protrude to a very limited extent, which severely limits the choice of materials and shape design. Alternatively, composite material components, adhesives, and / or cast (potting) materials can be used in the magnetic flux propagation region. However, it is very difficult to achieve the high requirements for temperature stability and mechanical strength with these materials. [Overview of the Initiative]

[0009] Against this backdrop, the present invention is based on the objective 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 is provided having a stator core and a torsionally rigid winding housed within the stator core, wherein the conductor bars of the torsionally rigid winding extend spirally in a first rotational direction on the radially inward side, and the conductor bars of the torsionally rigid winding extend spirally in an opposite second rotational direction on the radially outward side; 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 each annular base, a predetermined angular section of the annular base is associated with each permanent magnet, and the permanent magnets are designed and positioned on each base such that the angular section is displaced circumferentially in the axial path, thereby 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 directed toward the first rotational direction, and the magnetic field of the outer rotor extends obliquely in a second direction directed toward the second rotational direction; in particular, a radial magnetic flux double rotor machine for wheel hub drive is provided.

[0011] The fundamental finding of this invention is that in radial flux double rotor machines, magnetic field distortion can occur due to changes in the axial magnetic field. The magnetic field has its full amplitude only at the axial center of the machine. The amplitude of the magnetic field weakens at both ends of the axial direction of the machine. Another fundamental discovery is that distortion of the magnetic field leads to a shift in the maximum value of the magnetic field, resulting in a decrease in torque.

[0012] The underlying concept of the present invention is to provide a special combination of electric synchronous machines having a double rotor, wherein the stator has a stator core and a winding with high torsional rigidity housed therein for torque support, and permanent magnets are arranged to be shifted circumferentially along the axial direction of each rotor to generate oblique magnetic fields.

[0013] The individual conductor bars of the winding, which have high torsional rigidity, are axially positioned along the helical curve of the stator groove and along the first and second rotational directions corresponding to the radially inward and radially outward stator grooves, and are connected at the ends of the conductors. It is preferable that material connections by welding or soldering are 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 from conductor bars connected to each other, particularly in the form of a bar structure. The bar structure formed by the conductor bars is advantageously designed to have high torsional rigidity and to transmit moments around the central axis of the stator. This gives the windings a torsionally rigid shape and connects the windings to the stator core by fitting for torque support.

[0014] Furthermore, the conductor bars are designed to be thick enough 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 side lengths of several millimeters.

[0015] The selected lead angle (which is also the set angle) of the stator groove or the helix drawn therein 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 relative to the central axis and surrounds one magnetic pole of each rotor. Thus, despite the functional integration, the stator can be manufactured in a very simple manner, achieved using very few parts and relatively simple conventional connection techniques, and therefore the manufacturing process is also very simple.

[0016] The stator designed in this manner, together with the inner and outer rotors according to the present invention, can constitute an electromachine according to the present invention. The torsionally rigid winding involves dividing the stator into a radially inner and outer section, where the conductor bars of the torsionally rigid winding in the radially inner section are arranged helically in a first rotational direction, and the conductor bars of the torsionally rigid winding in the radially outer section are arranged helically in the opposite second rotational direction. As a result, the conductor bars are continuously displaced (tangentially) in the axial position of the electromachine, so that the magnetic field generated by the torsionally rigid winding changes in the axial position of the electromachine. Consequently, the magnetic field has its maximum amplitude only at the axial center of the electromachine where conductor bars of the same strand and current direction overlap. Due to the basic shape, the amplitude of the magnetic field decreases toward both ends of the electromachine in the axial direction. The average values ​​over the entire length are of particular importance for the resulting flux linkage and the torque of the electromachine.

[0017] In addition to the decrease in magnetic field amplitude, at both axial ends of the electromachine, rotational displacement of the conductor bars relative to each other also causes tangential distortion of the magnetic field, leading to a tangential displacement of the maximum magnetic field. Such distortion of the magnetic field, in conventional permanent magnet arrangements, leads to a decrease in torque because the rotor's permanent magnets are not in the optimal position for torque generation.

[0018] Therefore, according to the present invention, the torque reduction due to magnetic field distortion is offset by the new arrangement of permanent magnets. For this purpose, the permanent magnets of each rotor are axially shifted along the circumferential direction to generate oblique magnetic fields. The opposingly inclined magnetic fields generated in the inner and outer rotors extend in two oppositely inclined directions, corresponding to the respective opposite rotational directions of the highly torsionally rigid winding conductor bars. Advantageously, the axial displacement along the circumferential direction of the permanent magnets according to the present invention has a positive effect on the generated torque, particularly allowing for a torque increase of up to 10% compared to an uninclined arrangement of permanent magnets in the inner and outer rotors.

[0019] The rotor is preferably made of a soft magnetic solid material with 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, prevent the generation of unacceptably large losses due to eddy currents in the rotor. In this design, relatively high efficiency can be advantageously achieved, and the rotor can still be manufactured at a very low cost.

[0020] The stator support, which engages with windings that have particularly high torsional rigidity, is firmly connected to the base, which is the stationary part of the electromachine, in an appropriate manner. One possible embodiment for this purpose is to provide recesses, such as through holes, for non-fitting fasteners, such as screws. However, as an alternative or addition, the use of fitting fasteners and / or joints between materials may also be considered.

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

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

[0023] Furthermore, this high torque can already reach four-digit ranges with respect to the mounting size within the dimensions of conventional automotive wheels, particularly greater than 1000 Nm, preferably greater than 1500 Nm, and particularly preferably exceeding 5000 Nm. Thus, it has already reached 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 integration become possible.

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

[0025] According to a preferred embodiment, the annular substrate is made of solid material. The highly torsionally rigid winding first offers 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, costs can be saved 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 substrate. 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 substrate, 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 freely adjusted. In this way, the reduction in 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 from the attack angle, particularly multiples 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 angles of the individual axial sections relative 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 variant of the radial flux double-rotor machine according to the present invention is provided that is easy to manufacture and is thus particularly advantageous in terms of manufacturing cost. Since the number of axial sections remains small, the alignment and assembly of the sections remain relatively simple, but the torque achievable during operation is significantly increased.

[0030] In other embodiments, the permanent magnets have their edges aligned along a predetermined inclination angle. Thus, radial flux double rotor machines are provided that can be adjusted and designed using integrated permanent magnets according to requirements regarding a predetermined inclination angle. When the permanent magnets have flat surfaces, if they are inclined on the inner or outer circumferential surfaces of each annular substrate, their shape will create a small gap between the permanent magnets and the substrate in some parts. This gap is preferably filled with a material connecting medium when the permanent magnets are material-connected to the annular substrate. Material connection can be achieved, for example, by a suitable adhesive.

[0031] According to other embodiments, the permanent magnet has an oblique parallelogram shape. The parallelogram-shaped permanent magnet also has one, in particular the same, resulting total inclination angle in the circumferential direction. In this way, the parallelogram-shaped permanent magnet avoids leaving the surface of the annular substrate empty or protruding from the surface. As a result, the surface area of ​​the annular substrate can be optimally utilized. Placing the parallelogram-shaped permanent magnet inside / on the annular substrate also creates gaps due to the shape. However, these gaps can be filled by a material connecting medium, for example, if the permanent magnet is connected to the annular substrate by material connection. Material connection can be achieved, for example, by a suitable adhesive.

[0032] According to other embodiments, the permanent magnets can also be formed as rectangles, particularly narrow rectangles. Each corner of the permanent magnet can either leave a relatively small surface area open on the respective annular substrate, or the corner can protrude above it. Since the dimensions of the permanent magnets, particularly their width, are selectable, the open or protruding areas can thus be adjusted. Thus, radial flux double rotor machines are provided that can be designed in a simple manner to meet the requirements. In other embodiments, other arrangements of permanent magnets are also conceivable to produce the desired gradient magnetic field.

[0033] According to one embodiment, the windings are 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 members, particularly entirely, via windings with high torsional rigidity. In this way, all other types of force support devices for the stator core can be advantageously omitted.

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

[0035] According to one embodiment, the radially inner layer and radially outer layer of the winding each have the thickness of an individual conductor bar. That is, each phase of the winding is formed by the cross-section of an individual conductor bar. Such a winding design according to the present invention is made possible in particular by a special design of a radial flux double rotor machine, and its magnetic symmetry prevents current displacement to the surface otherwise present in the conductor. In this way, a relatively thick conductor cross-section can be realized, and nevertheless a relatively uniform current distribution is achieved across 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 may be a rod having a rectangular cross-sectional shape with a side length of several millimeters, for example, in the range of 2 mm to 6 mm, and especially in the range of 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 in the conductor with respect to the radial axis of the cross-section. In particular, this relates to the twisting of the conductor bars, especially non-circular conductor bars, around the central axis of the stator or machine. Depending on the helical path, the conductor bars may be further bent. In this case, the inner and outer layers intersect each other, i.e., twisted in opposite directions, and twisted and possibly bent. In this way, the arrangement of the conductor bars is ideally aligned from a mechanical standpoint at each point of the stator core for force transmission to the stator core, thereby ensuring that each conductor bar is uniformly loaded over its length. As a result, in the bar structure, the conductor bars favorably absorb mainly tensile and compressive stresses when subjected to tangential forces. In this way, load peaks and deformations of the conductor bars are avoided. In particular, mechanical stresses can be significantly reduced compared to designs using linear conductors parallel to the axis.

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

[0038] This creates a bar structure with high torsional rigidity in addition to the conductor loop, allowing the winding to absorb high torque without causing unacceptably large deformations and / or stress states when the axially accessible ends of the winding are fixed. Thus, a self-supporting winding design is possible using only the winding material, such as copper, without additional support means or members.

[0039] According to another embodiment, the stator core comprises a stacked stator core having stator grooves that extend helically according to the winding path, wherein the inner stator grooves in the radially inner portion of the stator extend according to a first rotational direction, and the outer stator grooves in the radially outer portion of the stator extend in opposite directions according to a second rotational direction. The winding or a self-supporting bar structure formed therefrom is embedded in the stacked stator core. Similar to the conductor bars of the winding, the stator grooves also change tangentially depending on their axial position, forming a helical shape. The direction of the change in position follows that of the conductor bars, i.e., the centerlines of the radially outer grooves and the radially inner grooves each trace a helix corresponding to the first or second rotational direction, with opposite rotational directions.

[0040] In other embodiments, to manufacture the stator core shape according to the present invention having radially inward and outward stator grooves extending in opposite helical directions, other manufacturing methods known to those skilled in the art, in particular additional manufacturing methods such as sintering processes, may also be considered.

[0041] According to one embodiment, only a single conductor bar is placed in each stator groove of the stacked stator core. As already described in relation to windings, the conductor bars of the inner and outer stator grooves intersect each other helically by torsion around the central axis of the machine, and the ends of the conductors of the inner and outer layers are guided toward each other. At both ends of the conductor bars, the conductor bars are connected to each other to be electrically connected, in particular by radially arranged conductor bar pieces and / or by material connections, for example, by welding or brazing.

[0042] According to one embodiment, conductive bars connected to conduct an inner layer and an outer layer together form a corrugated winding strand. The winding strand can be interconnected by suitable interconnections known to those skilled in the art to form a rotating magnetic field generating winding having a desired or adjustable number of strands. The number of phase windings to maintain voltage is obtained directly by the quotient of the number of grooves in the numerator and the product of the number of phase windings and the number of parallel branches in the numerator. 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 sheets of the laminated stator core are each formed in the same shape, having a plurality of recesses provided for forming stator grooves. The helical path of the stator grooves is provided by laminating the stator sheets in a twisted arrangement relative to one another. In this way, the laminated stator core can be manufactured in a very economical manner, as the same mold can be used for all parallel or laminated stator sheets. Thus, two adjacent stator sheets are positioned slightly twisted relative to each other by a predetermined angle around their central axis, and their recesses are positioned to overlap each other in accordance with the helical path.

[0044] In another embodiment, the laminated stator core includes an inner partial package having radially inward stator grooves and an outer partial package having radially outward stator grooves, wherein the stator sheets of the inner partial package are each designed to have the same shape, and the stator sheets of the outer partial package are each designed to have the same shape. Furthermore, the stator sheets of the inner partial package are laminated according to a first rotational direction of the conductor bars, and the stator sheets of the outer partial package are laminated according to a second rotational direction of the conductor bars, and are rotated in opposite directions by a predetermined rotational angle around the central axis. In another embodiment, the twist angle of the stator sheets around the central axis is the same as the sweep angle of the stator rod. In this way, the reverse helix of the stator grooves can be achieved with minimal manufacturing effort. Nevertheless, since the same mold can be used for all parallel or laminated stator sheets of the inner partial package and the same mold can be used for all parallel or laminated stator sheets of the outer partial package, a very economical manufacturing method is still possible. Therefore, two adjacent stator lamellae of the inner partial package are slightly twisted relative to each other in a first rotational direction by a predetermined twist angle around the central axis, and two adjacent stator lamellae of the outer partial package are slightly twisted relative to each other in a second rotational direction by a predetermined twist angle around the central axis. In this way, the recesses of the stator lamellae of the inner partial package and the recesses of the stator lamellae of the outer partial package are arranged to overlap each other on opposite sides, which corresponds to opposite helices.

[0045] According to one embodiment, the stator sheets of the laminated stator core are each formed in the same shape, having a plurality of recesses provided for forming stator grooves. The helical path of the stator grooves is provided by laminating the stator sheets in a twisted arrangement. In this way, the laminated stator core can be manufactured in a very economical manner, as the same mold can be used for all parallel or laminated stator sheets. Thus, two adjacent stator sheets are positioned slightly twisted relative to each other by a predetermined angle around their central axis, with their recesses overlapping each other in correspondence with the helix.

[0046] According to another embodiment, the stator sheets are formed with varying recesses for forming stator grooves. The helical path of the stator grooves is provided by the different distances between the recesses in each stator sheet. In this regard, for each position of the stator sheet in the laminate, individually matching stator sheet shapes are manufactured, thereby allowing the individual shapes to be repeated within the laminate. In this case, manufacturing can be achieved, for example, by an optical cutting process, particularly a laser optical cutting process which offers greater freedom in terms of shape than a press working process. It is also conceivable to use several separate cutting dies for each of the different stator sheet shapes if the cutting dies offer a high degree of freedom in shape or if the quantity is very large.

[0047] In another development, recesses for the radially inner and radially outer stator grooves are integrally formed on a common stator sheet, and the opposite helical paths of the radially inner and radially outer stator grooves are brought about by the continuous displacement of the inner and outer stator grooves relative to each other from stator sheet to stator sheet. In this case as well, a shape of the stator sheet is created that matches individually for each position of the stator sheet in the laminate, thereby allowing the individual shapes to be repeated within the laminate. Here again, highly flexible cutting processes such as laser cutting are used in manufacturing. By manufacturing the inner and outer recesses integrally in this way, the number of parts can be effectively reduced.

[0048] According to one embodiment, the stator lamina has a linear, in particular, punched edge. The width of the recess provided for the stator groove is greater than the width of the conductor bar by an amount predetermined by the pitch of the helical shape of the stator groove and the thickness of the stator lamina. Thus, the gap width or continuous width of the stator groove, reduced by the offset between the recesses of the stator lamina, substantially corresponds to the width of the conductor bar. In practice, a continuous gap width of the stator groove is provided that is slightly larger than the width of the conductor bar in order to provide the clearance fitting necessary for inserting the conductor bar. Thus, the edges of the stator groove are stepped, with each step being the thickness of the lamina, and the conductor bar is evenly supported therein. In this way, torque support is evenly distributed over the entire thickness of the laminated stator core or over the entire length of the conductor bar housed in the laminated stator core.

[0049] In one embodiment, the angle swept by each stator groove is smaller than the angle swept by each conductor bar. Each sweep angle refers to a rotation around the central axis of the stator. The difference in sweep angles is due to the conductor bar being longer than the stator groove because it protrudes axially beyond the stator core. The helical path is also continued, resulting in a larger sweep angle. This difference is provided to ensure sufficient access to the ends of the windings for joining, particularly welding, the ends of the conductor bars after insertion into the stator grooves. Furthermore, this allows the windings to engage with a support device or its support members in an axially offset state relative to the stator core.

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

[0051] According to one embodiment, the ratio of the angle swept by the stator grooves to the angle swept by the conductor bars is in the range of 0.6 to 0.8, particularly between 0.6 and 0.75, preferably between 0.6 and 0.7. This ratio (magnetic pole coverage) provides optimal conditions between losses due to current heat and torque utilization within this range.

[0052] According to one embodiment, the winding protrudes beyond the stator core at at least one axial end. Furthermore, a support device is provided which is positioned axially offset from the stator core and designed to engage with the winding by mating at at least one axial end for torque support.

[0053] In another advantageous development, the support device comprises a support member having support grooves that correspond to the helical arrangement of the conductor bars and engage with the conductor bars. Thus, the fitting and embedding of the conductor bars in the support member is provided to support torque at the axial end. Preferably, all conductor bars are engaged so that the torque support is transmitted uniformly or evenly throughout the entire winding bar structure.

[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 non-fitting fasteners such as screws, although connections that lock by fitting fasteners or materials are also conceivable.

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

[0056] According to one embodiment, the support device includes a radially inner support member for engaging with the radially inner layer of a conductor bar and a radially outer support member for engaging with the radially outer layer of a conductor bar. In this embodiment, the support members may be annular in shape, and the inner support member has grooves or teeth on its outer circumference corresponding to the path of the inner layer of the conductor bar in order to receive the radially inner conductor bar by fitting, and the outer support member has grooves or teeth on its inner circumference corresponding to the path of the outer layer of the conductor bar in order to receive the radially outer conductor bar by fitting. In particular, the grooves or teeth are along their respective helical paths. The placement of the grooves on the inner or outer circumference allows for easy access for machining, thereby enabling the support members to be manufactured easily.

[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%, and particularly preferably 28% to 32%, of the torsion angle of the stator lamination 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%, and particularly preferably 28% to 32%, of the torsion angle of the stator lamination of the outer partial package. Due to the fact that the distortion of the magnetic field does not perfectly follow the path of the stator groove of each stator lamination, the resulting total tilt angles of the permanent magnets of the inner and outer rotors are smaller than the torsion angle of the stator lamination. In this way, the ratio between the torsion angle of the stator lamination and the resulting total tilt angle of the permanent magnets provides a particularly advantageous design that results in an optimized torque increase.

[0058] According to other embodiments, the permanent magnets of the inner and outer rotors have a predetermined tangential pole width, and the stator core has a radial yoke thickness in the range of 5% to 25%, preferably 10% to 20%, and particularly preferably 12.5% ​​to 17.5% of the tangential pole width. The tangential pole width is, in particular, the local tangential pole width, preferably representing the common tangential width of the poles of all permanent magnets. Furthermore, the maximum tangential pole width in the cross-section of the machine is calculated from the quotient of the machine radius multiplied by the angle of one revolution (2π or 360°) and twice the number of pole pairs. To support a specific tangential flux at both ends of a radial flux double rotor machine, the radial yoke thickness of the stator core can be increased to reduce magnetic resistance. Thus, the radial yoke thickness adopted for the stator can be designed to be slightly increased compared to a conventional yokeless design, but without significantly increasing the weight of the laminated stator core.

[0059] According to one embodiment, the stator core is still designed to guide radial magnetic flux primarily. Therefore, the so-called "yoke-less" design of the stator core still does not have significant magnetic flux guidance in the circumferential or tangential directions, particularly at the axial center of the machine.

[0060] In one embodiment of a radial flux double rotor machine, the support members are fixed to the base, thereby guiding torque to the stationary part of the electromachine. For this purpose, the support members may be individually mounted to the base of the machine, for example, the housing. Alternatively or additionally, the inner support members and the outer support members may be fixed to each other.

[0061] According to one embodiment of the stator, the support members include a thermally conductive material, particularly a metal, preferably an aluminum alloy. In particular, both support members may include such a material. This allows for high mechanical strength, as well as heat dissipation from the windings through the support members.

[0062] According to one embodiment of a corresponding radial flux double rotor machine equipped with a support device containing a thermally conductive material, the base further includes a heat sink designed to absorb heat dissipated from the stator, particularly from the windings, through 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 in thermal contact with the machine's actively cooled heat sink. In this way, current heat loss occurring 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 and second rotors. The angles swept by the conductive bars are designed to form a conductive loop for each pole of the rotor. Thus, 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 relating to a method for manufacturing a stator includes the steps of: providing a stator core having radially outer stator grooves that form a helix, each having a first direction of rotation; and radially inner stator grooves that form a helix, each having opposite directions of rotation; inserting individual conductor bars along the helix into the inner and outer stator grooves; and connecting the conductor bars inserted into the inner and outer stator grooves at both ends of the conductor bars to form a conductor loop.

[0065] According to one embodiment of the manufacturing method, the provision of a stator core involves the manufacture of a laminated stator core, in which individual stator sheets having recesses for forming stator grooves are laminated in a twisted manner relative to one another. In this way, the laminated stator core can be manufactured in a very economical manner because the same mold can be used for all parallel or laminated stator sheets. Thus, two adjacent stator sheets are slightly twisted relative to each other by a predetermined angle about the central axis such that the recesses are positioned to overlap each other in correspondence with the helical path. Individual stator sheets having such a shape are advantageously manufactured by press-forming or laser-cutting individual sheets from electrical steel sheets.

[0066] In another development of this method, the laminated stator core comprises an inner partial package and an outer partial package, where all stator sheets of the inner partial package are formed to the same shape, and all stator sheets of the outer partial package are formed to the same shape, and the stator sheets of the inner partial package that form the inner stator groove and the stator sheets of the outer partial package that form the outer stator groove are laminated so as to be twisted in opposite directions. In this case, all sheets of the inner partial package and the outer partial package can have the same shape, and the manufacturing process can be made very economical. Therefore, the same cutting die can be used for all parallel or laminated stator sheets of the inner partial package and for all parallel or laminated stator sheets of the outer partial package.

[0067] Two adjacent stator lamellae in the inner partial package are slightly twisted relative to each other in a first direction by a predetermined angle around the central axis, and two adjacent stator lamellae in the outer partial package are slightly twisted relative to each other in a second direction by a predetermined angle around the central axis. In this way, the recesses of the stator lamellae in the inner partial package and the recesses of the stator lamellae in the outer partial package are arranged in an opposite overlapping manner corresponding to opposite helical paths. In this way, the opposite helical path of the stator groove 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 sheets of different shapes, with recesses for inner and outer stator grooves provided in a common stator sheet, and the helical pitch is achieved by the relative continuous displacement of the inner and outer stator grooves of each stator sheet, particularly using a flexible press working or laser cutting process. In this case, the inner and outer stator grooves are provided in a single stator sheet, and the helical shape of the stator grooves is achieved, for example, by moving the recesses relatively and continuously during the cutting process of the individual sheets by a flexible press working or laser cutting process. This has the advantage of requiring fewer parts and fewer manufacturing steps, and the resulting stator sheet or stator core as a whole has higher mechanical strength.

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

[0070] In one embodiment, the stator thus manufactured can be used to manufacture a radial flux double rotor machine, further comprising the steps of: providing a mechanically fixable base and a support device adapted to engage with a winding by mating at at least one axial end for torque support; fixing the support device to the base; and providing a double rotor comprising an inner rotor and an outer rotor, each having a common central axis with an annular base designed for magnetic flux propagation, a plurality of permanent magnets fixed to each annular base, a predetermined angular section of the annular base associated with each permanent magnet, and the permanent magnets formed and positioned on each base such that the angular section is displaced circumferentially along the axial direction such that the permanent magnet generates 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 toward a first rotational direction, and the magnetic field of the outer rotor extends obliquely in a second direction toward a second rotational direction.

[0071] The above embodiments and other developments can be combined with each other in any way as desired, if useful. In particular, all features of the stator can be adapted to a method for manufacturing the stator, and vice versa. Furthermore, all features of the stator can be adapted to a 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 invention described above or below with respect to examples of embodiments not expressly mentioned. In particular, those skilled in the art will also add individual aspects as improvements or additions to each basic form of the invention. [Brief explanation of the drawing]

[0073] The present invention will be described in more detail below with reference to the examples of embodiments shown in the schematic diagrams of the drawings. [Figure 1]This is an exploded perspective view of a radial flux double rotor machine having a stator and a double rotor. [Figure 2] This is a disassembled perspective view of the double rotor. [Figure 3] This is a plan view of the two axial sections of a permanent magnet. [Figure 4] This is a schematic cross-sectional view showing a portion of the inner rotor and outer rotor equipped with permanent magnets. [Figure 5] This is a plan view of a parallelogram-shaped permanent magnet. [Figure 6] This is a schematic cross-sectional view showing a portion of the cross-section of the inner rotor and outer rotor, which are equipped with parallelogram-shaped permanent magnets. [Figure 7] This is a perspective view of the winding. [Figure 8] This is a perspective view of the stator core. [Figure 9] This is a cross-sectional view of a radial flux double rotor machine. [Figure 10] This is a cross-sectional view of a radial flux double rotor machine according to another embodiment. [Figure 11A] This is a cross-sectional view of a radial flux double rotor machine, illustrating the distortion of the magnetic field. [Figure 11B] This is a cross-sectional view of a radial flux double rotor machine at a different axial position than Figure 11A, and the distortion of the magnetic field is depicted. [Figure 11C] Figures 11A and 11B show cross-sectional views of a radial flux double rotor machine at different axial positions, illustrating the distortion of the magnetic field. [Figure 12] This is a schematic longitudinal cross-section of the stator. [Figure 13] This is a schematic longitudinal cross-sectional view of a radial flux double rotor machine. [Figure 14] This is an exploded perspective view of a radial flux double rotor machine according to one embodiment. [Figure 15] This is an exploded perspective view of a stator according to one embodiment. [Figure 16] This is an exploded perspective view of a radial flux double rotor machine according to another embodiment. [Figure 17]Figure 16 shows a perspective view of the assembled radial flux double rotor machine. [Figure 18] This is a longitudinal cross-sectional perspective view of a radial flux double rotor machine according to another embodiment. [Figure 19] This is an exploded perspective view of a stacked stator core package. [Figure 20] This is a schematic longitudinal cross-sectional view of the stator groove. [Figure 21] This is a plan view of the winding. [Figure 22] This is a perspective view of the FEM simulation of the winding under load. [Figure 23] This is a perspective view of an FEM simulation of a winding under load, as a comparative example where the conductor bar is designed in a straight line. [Figure 24] This is a flowchart showing the manufacturing method of a stator. [Modes for carrying out the invention]

[0074] The accompanying drawings are intended to further enhance the understanding of embodiments of the present invention. The drawings illustrate embodiments and, together with the detailed description, serve to illustrate the principles and concepts of the present invention. Many other embodiments and advantages mentioned will become apparent by reference to the drawings. The components in the drawings are not necessarily shown to scale relative to one another.

[0075] In the drawings, identical members, features, and components having the same function and effect are denoted by the same reference numeral unless otherwise specified.

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

[0077] The stator 1 comprises a stator core 2 and a torsionally rigid winding 3 housed within it. On the radially inward side of the stator 1, the conductor bars 6 of the torsionally rigid winding 3 extend spirally in a first rotational direction. On the radially outward side of the stator 1, the conductor bars 6 of the torsionally rigid winding 3 extend spirally in the opposite second rotational direction.

[0078] The double rotor 100 comprises an inner rotor 12 and an outer rotor 13. The inner rotor 12 and the outer rotor 13 each have annular bases 102 and 103, respectively. The annular bases 102 and 103 are designed for magnetic flux guidance and have a common central axis M. Multiple permanent magnets 29 are mounted on each of the annular bases 102 and 103. Each permanent magnet 29 is assigned a predetermined angular section 32 and 33 in the cross-section of the annular bases 102 and 103. The predetermined angular sections 32 and 33 extend in an arc shape along the circumferential direction of the annular bases 102 and 103.

[0079] The permanent magnets 29 are formed and arranged on annular bases 102 and 103, respectively, such that predetermined angular intervals 32 and 33 are offset circumferentially in the axial direction. As a result, the permanent magnets 29 generate magnetic fields 34 and 35 that 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 rotation direction of the winding 3, which has high torsional rigidity. The magnetic field 35 of the outer rotor 13 extends obliquely in a second direction toward the second rotation direction of the winding 3, which has high torsional rigidity.

[0080] The magnetic fields 34 and 35 of the permanent magnets 29, which extend in opposite directions, are shown in Figure 1 by diagonally drawn dashed arrows. The magnetic field propagation lines of magnetic fields 34 and 35 extend diagonally in opposite directions on the permanent magnets 29 of the inner rotor 12 and the outer rotor 13, as shown in the figure.

[0081] The design and arrangement of the permanent magnets 29 for displacing the angular sections 32 and 33 in the axial path are not limited to the embodiments shown herein 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. Multiple permanent magnets 29 are arranged on the inner circumferential surface of the annular base 103 of the outer rotor 13.

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

[0084] In this example, the permanent magnet 29 is divided into multiple axial sections 30. However, in other embodiments, other designs and arrangements of the permanent magnet 29 are conceivable to arrange the angular sections 32, 33 with axial offsets.

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

[0086] Figure 3 is a plan view showing the permanent magnet 29. The permanent magnet 29 is arranged on annular bases 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 exemplary divided into multiple axial sections 30. Each axial section 30 is assigned an angular section 32, 33 (not shown) of the base body, and these angular sections 32, 33 are offset from the adjacent axial section 30 by an attack angle θ around the central axis M.

[0088] The resulting total inclination angle φ of the permanent magnets arises from the attack angle θ, particularly from multiples of the attack angle θ, due to the shape. If there is a predetermined number of axial sections 30 of n for each permanent magnet 29, the resulting total inclination angle φ is determined from the attack angle θ by the relationship φ = n * θ. Furthermore, the predetermined inclination 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 inclination angle may be defined differently from that shown. In this regard, ε shown in Figure 3 is simply illustrated as the angle projected onto the circumferential surface of the permanent magnet 29.

[0089] As shown in Figure 3, in the illustrated embodiment, the axial section 30 is positioned so that its long side is parallel to the central axis M. In this embodiment, the surfaces of the annular base bodies 102, 103 are optimally utilized. In other embodiments, the edges of the axial section 30 may be positioned on the annular base bodies 102, 103 at an angle to the central axis, for example, the edges of the axial section 30 may be aligned along a predetermined inclination angle ε. Furthermore, in other embodiments, other orientations of the axial section 30 are possible on the surfaces of the annular base bodies 102, 103 that result in a desired total inclination angle.

[0090] Figure 4 is a schematic cross-sectional view of a portion of the inner rotor 12 and outer rotor 13, which have permanent magnets 29. As shown in Figure 3, the permanent magnets 29 are arranged axially front to back on the annular bases 102 and 103. Furthermore, the total inclination angle φ and attack angle θ around the central axis M (not shown) of the resulting radial flux double rotor machine 10 are shown.

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

[0092] As described above, the resulting total circumferential inclination angle φ is determined by the attack angle θ of the axial section 30 and the number of axial sections 30. Furthermore, in the rectangular design of the axial sections 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 base bodies 102, 103. This gap can be filled with a material connecting medium, for example, when the axial sections 30 of the permanent magnet 29 are integrally connected to the annular base bodies 102, 103 by material connection. Material connection can be achieved, for example, by a suitable adhesive. However, it should be noted that other mechanisms and methods for mounting are also possible, particularly those without a gap between each axial section 30 and the annular base bodies 102, 103. For example, local recesses in the rotor for gap compensation can be considered as an alternative or additional measure. Furthermore, in other embodiments, the inner and outer permanent magnets may be the same size or different sizes, as shown herein, preferably to cover the same angular section aligned radially.

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

[0094] Figure 6 is a schematic cross-sectional view showing a portion of the inner rotor 12 and outer rotor 13 equipped with parallelogram-shaped permanent magnets 29. Similar to Figure 4, the resulting total inclination angle φ in the circumferential direction around the central axis M can be observed. The resulting total inclination angle φ represents the circumferential sweep angle caused by the oblique edges 31 (not shown) of each permanent magnet 29. The problem of gap formation in the inner rotor 12 and outer rotor 13, as explained with reference to Figure 4, can be solved in a similar manner for the illustrated parallelogram-shaped permanent magnets 29. The relative arrangement of the permanent magnets 29 on the annular bases 102, 103 is provided as a function of the resulting total inclination angle φ. The total inclination angle φ in the circumferential direction is equal in magnitude in opposite directions for the illustrated permanent magnets 29 on the inner rotor 12 and outer rotor 13, because the directions of rotation 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, the inner and outer permanent magnets can be the same size to reduce costs as part of an integrated strategy.

[0096] Figure 7 is a perspective view of winding 3. The winding 3 is composed of conductor bars 6 that extend spirally along the central axis M. Therefore, the conductor bars 6 are not only arranged to interlock with each other, but are also twisted together along the spiral path.

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

[0098] The opposite twists and rotations of the radially inner layer 15 and 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 a 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. Thus, the ends of the conductor bar 6 of the inner layer 15 and outer layer 14 are arranged overlapping each other in the same orientation. Thus, the radially inner layer 15 and outer layer 14 of the conductor bar 6 can be conductively connected in a simple way, exemplifying here, via radially extending conductor bar pieces 17 welded to the conductor bar 6.

[0099] It should be noted that the windings shown here are not manufactured independently, but are always manufactured in combination with the stator core 2, as will be explained in more detail with reference to Figure 23.

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

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

[0102] The stacked stator core 18 comprises an inner partial package 23 having radially inward stator grooves 20 and an outer partial package 24 having radially outward stator grooves 19. The stator sheets 22 of the inner partial package 23 are each designed to have the same shape, and the stator sheets 21 of the outer partial package 24 are each designed to have the same shape. The stator sheets 22 of the inner partial package 23 are stacked according to a first rotational direction of the conductor bar 6 (not shown), and the stator sheets 21 of the outer partial package 24 are stacked according to a second rotational direction of the conductor bar 6, and are twisted in opposite directions 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 the axial ends of the stacked stator core 18, resulting from the twisting of the individual stator sheets 21, 22 relative to each other.

[0103] In certain embodiments, the sweep angle α of the stator groove is the same as the torsion angle γ. Since the distortion of the magnetic field does not perfectly follow the path of the stator groove, the resulting total circumferential inclination angle φ must be smaller than the torsional angle γ. Therefore, the resulting total circumferential (not shown) inclination angle φ of the permanent magnets 29 of the inner rotor 12 is in the range of 20% to 40% of the torsional angle γ of the stator slub 22 of the inner partial package 23, and / or the resulting total circumferential inclination angle φ of the permanent magnets 29 of the outer rotor 13 is in the range of 20% to 40% of the torsional angle γ of the stator slub 21 of the outer partial package 24. When the resulting total circumferential inclination angle φ matches the torsional angle γ as described above, the maximum increase in torque is obtained.

[0104] Figure 9 is a cross-sectional view of the radial flux double rotor machine 10. The illustrated arc-shaped cross-section of the radial flux double rotor machine 10 shows the conductor bars 6, permanent magnets 29, stator 1, inner rotor 12, outer rotor 13, and annular bases 102, 103. Furthermore, the tangential flux in the inner rotor 12 and outer rotor 13 and the radial flux in the stator 1 are also shown. In the illustrated embodiment, the stator 1 is formed "yokeless". Thus, although a stator yoke 38 extends between the conductor bars 6, it merely serves to mechanically connect the stacked stator cores 18 (not shown) of the stator 1. As shown in Figure 9, the stator yoke 38 is in the functionally relevant 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 adversely affects the efficiency of the radial flux double rotor machine 10 and, accordingly, causes an undesirable decrease in torque.

[0105] Figure 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 Figure 10 has a significantly thicker stator yoke 38 (outside scale) compared to the embodiment shown in Figure 9. The stator yoke 38 is explained by the radial yoke thickness 36 depicted.

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

[0107] In an embodiment comprising a permanent magnet 29 having a parallelogram shape, the cross-section of the permanent magnet 29 is crucial for the relationship between the tangential 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 (Figure 11A left, Figure 11B center, and Figure 11C right) 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 is equipped with a single-shaped permanent magnet 29 arranged in the axial direction. As can be seen in Figure 11, only the central cross-section of the radial flux double rotor machine 10 contains a uniform magnetic field, and the magnetic field lines within the stator 1 extend exclusively in the radial direction. In the left and right cross-sections of the radial flux double rotor machine 10, distortion of the magnetic field occurs as shown in the diagram. In the left and right cross-sections, the respective magnetic field lines are distorted in corresponding ways in the left and right cross-sections, particularly within their respective stators.

[0110] Furthermore, the displacement of the conductor bars 6 across the axial positions (front end, axial center, and rear end) of the radial flux double rotor machine 10 is evident from the three cross-sectional views. Only in the central view are conductor bars 6 of the same strand (U, V, W) and the same current direction (+, -) aligned vertically. As a result, the magnetic field exhibits maximum amplitude only at the axial center of the radial flux double rotor machine 10. Due to the fundamental geometric relationship between the conductor bars 6 and the permanent magnets 29, the amplitude of the magnetic field decreases toward both axial ends (left and right cross-sectional views) of the radial flux double rotor machine 10. Consequently, distortion of the magnetic field occurs, and the torque decreases because the rotor's permanent magnets are not in the optimal position for torque generation. This is offset by the arrangement and design of the permanent magnets 29 on each annular base 102, 103 in the circumferential direction along the axial direction, as described with reference to Figures 1 to 6, so that the permanent magnets 29 generate magnetic fields 34, 35 extending obliquely with respect to the central axis M and are optimally positioned within the range of magnetic field distortion.

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

[0112] The winding 3 is self-supporting to support the torque of the stator 1 and protrudes beyond the stator core 2 at at least one axial end 4. The support device 5 is positioned axially offset from the stator core 2 and is connected to the winding 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 support device 5 through the self-supporting winding 3.

[0113] The windings contain a conductive material with low electrical resistance, preferably copper. The stator core 2 is preferably made of a soft magnetic material for magnetic flux propagation. The support device preferably contains a thermal conductive material, such as an aluminum alloy. Naturally, the windings 3 are electrically insulated.

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

[0115] The winding 3 is self-supporting in order to support the torque of the stator 1, protruding beyond the stator core 2 at at least one axial end 4 and supported on the base 11 via a support device 5. Therefore, the support device 5 is positioned axially offset from the stator core 2 and is fitted to the winding 3 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 positioned radially inward of the stator core 2, and the second rotor 13 is positioned radially outward of the stator core 2. The base 11 can be designed, for example, as a housing for the machine, in which case, in a purely exemplary embodiment, it consists of an L-shaped structure having two legs 7,8. The figure should not be understood as exhaustive, and rather the base may have further components and / or structural parts. The first leg 8 extends substantially radially, and the second leg 7 extends substantially axially at its furthest point from the central axis M.

[0117] In purely schematic terms, the support device 5 is shown as a single radially extending component, but it may be provided by multiple components and / or by other shapes designed to engage with the winding 3 by mating. The illustrated overlap between the winding 3 and the base 11 is purely illustrative and does not imply a direct connection. The winding 3 is preferably connected to the base 11 via the support device 5 for torque support.

[0118] Figure 14 is an exploded perspective view of a radial flux double rotor machine 10 according to one embodiment. The radial flux double rotor machine 10 comprises 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 positioned radially inward of the stator core 2, and the second rotor 13 is positioned radially outward of the stator core 2. The rotors 12 and 13 are preferably made of a soft magnetic solid material, and permanent magnets, so-called surface magnets, are attached as magnetic poles to their respective surfaces facing the stator core. The permanent magnets 29 are arranged as shown in Figures 1 and 2.

[0119] The base 11 is shown schematically here for clarity. As already mentioned in the description of Figure 13, the base 11 is fixed in place while attached to the support device 5. The base 11 is mechanically fixed to a reference system, for example, the axle support.

[0120] Figure 15 is an exploded perspective view of the stator 1 according to another embodiment. The stator 1 comprises windings 3, a stator core 2, and a support device 5, where advantageous exemplary embodiments of these components are shown in more detail in perspective.

[0121] The winding 3 consists of an inner layer and an outer layer, each having a plurality of conductor bars 6 connected to one another in a rod-like manner. The conductor bars 6 of the inner and outer layers are arranged spirally in opposite directions, and at both ends of the conductor bars, they are joined by material to radial conductor bar pieces 17 that connect the inner and outer layers.

[0122] The thicknesses of the inner and outer layers correspond to the thickness of the conductor bar 6, respectively. This means that the winding 3 is formed by a single conductor layer that forms a conductor loop with a relatively large cross-section in the form of a conductor bar 6.

[0123] A bar structure formed by multiple conductor bars increases the torsional rigidity of the winding, thereby enabling self-support for torque support. Therefore, multiple conductor bars 6 can form corrugated winding strands and be interconnected by suitable interconnecting means known to those skilled in the art, such as delta connections and star connections, which will not be described further, 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 two parts, as an example. For the assembly of the stator 1, the windings 3, the stator core 2, and the support device 5 are arranged nested within each other. After assembly, the components are coaxially aligned with each other along a common central axis M. The two-part support device 5 illustrated here is positioned axially offset from the other components and forms the innermost and outermost components of the stator 1. These are the inner ring and the outer ring, each designed to have grooves for mating and engaging with the conductor bars.

[0125] The stator core 2 of the two components illustrated here is formed by two stacked stator cores 18 that are spirally twisted relative to each other, as will be described in more detail with reference to Figure 19. In other embodiments, the stator core 2 and the support device 5 may each be designed from a single piece or more than two parts.

[0126] Figure 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 described here has substantially the same components as those described with reference to Figures 15 and 4. Shown on the left side of the figure in its assembled state are the stator core 2, windings 3, first rotor 12, and second rotor 13.

[0127] The support device 5 shown on the right is also formed from two parts, with different configurations for the annular inner support member 27 and the outer support member 28 of each part. The support members 27 and 28 are provided 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 to engage with the conductor bars 6 of the winding 3.

[0128] For this purpose, the support groove 26 is designed to be angled axially according to the helical path or pitch of the conductor bars 6 of the winding 3 so that it can engage with the conductor bars 6 of the winding 3.

[0129] The support members 27 and 28 are preferably made of a conductive metal, and more preferably an aluminum alloy. The two-part design of the support members 27 and 28 allows for easy access to the support groove 26 for mechanical processing or machining during manufacturing.

[0130] The inner support member 27 and the outer support member 28 each have a plurality of holes 9 circumferentially for attachment to the base 11. Exemplarily, the holes 9 are evenly distributed circumferentially along the pitch circle. The individual holes 9 are located slightly outside the body of the support member, and the support members 27 and 28 thus form a star shape on the circumference, each oriented away from the winding. Of course, other distributions of the holes 9 are possible, as are other types of fastening means for connection to the base 11.

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

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

[0133] Support members 27 and 28 are shown here engaged with the conductor bars 6 of the winding 3. It can be seen that the conductor bars 6 are positioned within each support groove 26, and all conductor bars are coupled to the support device by fitting. Thus, the torque supported via the winding 3 can be supported by the base 11 fixed in the hole 9 via the support device 5.

[0134] Figure 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 radial flux double rotor machine 10 shown in Figure 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 and 24 extend in an annular shape 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 outer layer 14 of the conductor bar 6 extending into the interior of the partial packages 23 and 24.

[0136] The illustrated radial flux double rotor machine 10 is a so-called "yokeless" design in which the yoke between the two teeth is not functionally relevant within the flux. Thus, although the stator yoke 38 extends between the conductor bars 6, it merely serves to mechanically hold the stacked stator cores 18 together. The radial yoke thickness can be designed to be correspondingly thin, and in the illustrated embodiment, it is exemplary about 10% of the total radial stator thickness. Furthermore, the relatively small yoke thickness reduces undesirable leakage flux within 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 radial stator thickness for this purpose.

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

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

[0139] Furthermore, the magnets on the surfaces of rotors 12 and 13 can also be seen in this cross-section. The first rotor 12 has multiple permanent magnets on its outer circumferential surface. The second rotor 13 has multiple permanent magnets on its inner circumferential 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 at a very low cost and high efficiency can be achieved.

[0141] Figure 19 is an exploded perspective view of the stacked stator core 18 of the stator core 2. As already mentioned, the stacked stator core 18 of the stator core 2 has an inner partial package 23 and an outer partial package 24. This helps to simplify the manufacture of the stator groove 19 which is rotated in opposite directions relative to each other, using the same inner stator lamellae 21 and outer stator lamellae 22 which are stacked in a manner rotated relative to each other and have recesses in the same positions.

[0142] In other embodiments, the stator lamina may be manufactured as a single piece, provided as a plurality of stator laminas of different shapes having recesses of different arrangements and laminated in the order necessary to form the stator grooves. In yet another embodiment, a completely integrated stator core 2 is also conceivable, which can be manufactured, for example, additively.

[0143] In the two-component configuration shown, the inner diameter of the outer package 24 is approximately equal to the outer diameter of the inner package 23. This allows the inner package 23 to be coaxially positioned within the outer package 24.

[0144] The partial packages 23 and 24 are constructed by laminating one of the individual annular stator sheets 21 and 22 onto the other. The stator sheet 21 of the outer partial package 24 is manufactured to have recesses distributed on its outer circumference in order to form the outer stator groove 19. The stator sheet 22 of the inner partial package 23 is manufactured to have recesses distributed on its inner circumference in order to form the inner stator groove 20. For example, manufacturing these stator sheets by press working is advantageous due to edge quality and very low manufacturing costs.

[0145] The inner stator groove 20 and the outer stator groove 19 form a spiral extending in opposite directions with the same pitch, and are characterized by a specified sweep angle α of the stator groove. The sweep angle α of the stator groove can be defined from the angle formed by the same stator rod position on one axial side of the stator core 2 and the other axial side of the stator core 2 with respect to the central axis M.

[0146] The stator grooves 19 and 20 are, here exemplary, designed as T-grooves having rectangular recesses with narrowed openings. These are specifically provided to receive conductor bars having a rectangular cross-section by mating. Of course, the shape of the recesses or stator grooves can be adapted to the shape of the conductor. Other cross-sectional shapes are also conceivable for this purpose.

[0147] Figure 20 is a schematic longitudinal cross-sectional view of the stator grooves 19 and 20. The usable or continuous gap width a of the stator grooves 19,20 within the stacked stator core 18 is substantially equal to the width of the conductor bar 6 housed within the stator core 2. The stator fins 21 and 22 have straight, particularly punched edges. Due to the offset of the fins relative to each other, the width b of the recesses provided for the stator grooves 19 and 20 is greater than the width d of the conductor bar 6 by an amount predetermined by the pitch δ of the helical shape of the path and the thickness t of the fins.

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

[0149] In the case of a straight, for example, punched edge of a thin sheet, the sheet thickness t and the attack angle (set angle) δ of the groove path pitch are factors that significantly affect the difference between the width b of the recess and the usable gap width a of the passage within the groove. This difference arises because the pitch angle must be compensated for on the one hand, and the stepped height difference of the laminated core on the other.

[0150] In the case of the limit of the infinitely thin plate, that is, when the pitch angle δ of the conductor bar is purely considered, the minimum size of the recess width b is as follows: b = 1 / cos(δ)*d On the one hand, the width b of the recess is provided to be even larger in order to further compensate for the actual plate thickness, and on the other hand, to provide a gap fit that allows for the insertion of the conductor bar.

[0151] The width b of the recess shown in Figure 20 is dimensional such that the gap width a between the stator grooves 19,20, which is reduced by the offset between the recesses of the stator sheets, forms a predetermined clearance fit with the width d of the conductor bar 6 inserted into the stator groove. Nevertheless, the contact is dimensional such that it is close enough to provide uniformly distributed power transmission or torque support between the laminated stator core and windings. Such dimensionality is achieved, in particular, by the fact that, on the one hand, each stator sheet is formed with equivalent high edge quality and rotated with equivalent offset, and on the other hand, only a single conductor bar 6 is placed in each stator groove 19,20 and its dimensions are constant.

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

[0153] Figure 21 is a plan view of winding 3. In this figure, the precise 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 can be clearly seen. Each end 16 of the conductor bar forms a connection point between the radially inner layer 15 and the radially outer layer 14.

[0154] In the illustrated embodiment, the winding has, for example, a total of 12 terminal contacts 31. In the case of a three-phase connection, three-phase operation is preferably 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] Figure 22 is a perspective view showing an FEM simulation of the loaded winding 3. Although some simplification was performed for the simulation, this is basically the winding shape shown in Figure 7. The illustrated scale relates to the stress within the winding; for example, if the cross-sectional shape of the conductor bar 6 is a rectangle of 5 mm × 3 mm, the scale ranges 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, i.e., they are arranged and formed in a helical manner or formed 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 the corresponding dimensions is depicted, as indicated by the thick arrows, and for example, if the cross-sectional shape of the conductor bar 6 is a rectangle of 5 mm × 3 mm, the maximum torque can be approximately 5000 Nm.

[0157] The spiral shape ensures that stress is distributed very evenly within the winding. Despite the exaggeration, almost no deformation is observed. This design significantly reduces stress peaks and, consequently, deformation.

[0158] The bar structure allows the winding 3 to self-support high torques without causing unacceptably large deformations and / or stress conditions when fixing the axially accessible winding ends. This is due in particular to the fact that the conductor bars 6 of the bar structure absorb mainly tensile and compressive stresses when subjected to tangential forces. Therefore, compared to designs using straight conductors parallel to the axis, mechanical stress can be significantly reduced.

[0159] Figure 23 is a perspective view of a comparative model of a linear design, showing the axial path of the load-bearing conductor bar 6. Comparing with Figure 22, it can be seen that, due to the linear design and axial path of the conductor bar, stress paths are concentrated on the left side of Figure 23, and large deformations of the conductor bar occur on the right side of Figure 23 due to locally high stress accompanied by large deformations. Here, the same stress scale and deformation expansion as in Figure 22 are set, demonstrating the effect of differences in structural arrangement on torsional stiffness.

[0160] Figure 24 is a flowchart of the manufacturing method for stator 1. The method includes a first step S1 of providing a stator core 2 having radially outer stator grooves 19, each spiraling, and radially inner stator grooves 20, each spiraling in the opposite direction. Another step S2 relates to the insertion of individual conductor bars 6 along the spirals passing through the inner and outer stator grooves 19, 20. The conductor bars are inserted in particular in the axial direction. Furthermore, a step S3 is provided in which the conductor bars 6 inserted into the inner and outer stator grooves are connected at the conductor bar ends 16 to form a conductor loop.

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

[0162] 1 stater 2 Stator Cores 3 windings 4 Axial end 5 Support device 6 Conductor bars 7 Second leg 8 1st leg 9 holes 10 Radial magnetic flux double rotor machine 11 Bass 12. First rotor / inner rotor 13. Second rotor / outer rotor 14 Radial outer layer 15 Radial inner layer 16 Conductor bar ends 17 Conductor bar pieces 18 Stacked stator cores 19,20 Stator grooves 21,22 Stator thin plate 23 Inner part of the package 24 Outer part of the package 25 Support member 26 Support groove 27 Inner support member 28 Outer support member 29 Permanent Magnets 30 Axial section 31. Diagonal edge 32,33 Predetermined angle section 34,35 Magnetic field 36 Yoke Thickness 37 Tangential width 38 Stater York 100 Double Rotor 102,103 cyclic substrate α Stator groove sweep angle Sweep angle of β conductor bar γ Torsion angle δ pitch angle ε is a predetermined inclination angle. θ Attack angle φ Total tilt angle a Gap width b Width of the recess d Width of the conductor bar M center axis t Plate thickness

Claims

1. A stator (1) having a stator core (2) and windings (3) housed therein, wherein the conductor bars (6) of the windings (3) extend spirally in a first rotational direction on the radially inward side of the stator (1), and the conductor bars (6) of the windings (3) extend spirally in the opposite second rotational direction on the radially outward side of the 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 base (102, 103) designed for magnetic flux propagation, Multiple permanent magnets (29) are fixed to the annular bases (102, 103), and a predetermined angular section (32, 33) of the annular bases (102, 103) is associated with each of the permanent magnets (29). The permanent magnets (29) are formed and arranged on each of the annular bases (102, 103) such that the predetermined angular intervals (32, 33) are shifted circumferentially along the axial direction, thereby generating magnetic fields (34, 35) that extend obliquely with respect to the central axis (M), with the magnetic field (34) of the inner rotor (12) extending obliquely in a first direction toward the first rotation direction, and the magnetic field (35) of the outer rotor (13) extending obliquely in a second direction toward the second rotation direction, in a radial flux double rotor machine (10).

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

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

4. The radial magnetic flux double rotor machine (10) according to claim 1, wherein the permanent magnet (29) is formed by dividing it into a plurality of axial sections (30), and each axial section (30) is assigned an angular section (32, 33) that is shifted by an attack angle (θ) around the central axis (M) with respect to an adjacent axial section (30), and as a result, a total inclination angle (φ) in the circumferential direction is generated from the attack angle (θ).

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

6. The radial magnetic flux double rotor machine (10) according to claim 4, wherein the permanent magnet (29) is divided into two axial sections (30).

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

8. The radial magnetic flux double rotor machine (10) according to claim 7, wherein the permanent magnet (29) has an oblique parallelogram shape.

9. The radial flux double rotor machine (10) according to claim 1, wherein the winding (3) comprises a radially inner layer (15) of the conductor bar (6) arranged spirally on the radially inner side of the stator (1), and a radially outer layer (14) of the conductor bar (6) arranged spirally in the opposite direction on the radially outer side of the stator (1).

10. The radial flux double rotor machine (10) according to claim 1, wherein the stator core (2) comprises a stacked stator core (18) having stator grooves (19, 20) that extend spirally in correspondence with the winding path, the inner stator groove (20) of the radially inner portion of the stator (1) extends along the first rotation direction, and the outer stator groove (19) of the radially outer portion of the stator (1) extends in opposite directions along the second rotation direction.

11. The radial flux double rotor machine (10) according to claim 10, wherein the stacked stator core (18) comprises an inner partial package (23) having an inner stator groove (20) radially inward and an outer partial package (24) having an outer stator groove (19) radially outward, the stator plates (22) of the inner partial package (23) are each designed to be the same shape, the stator plates (21) of the outer partial package (24) are each designed to be the same shape, the stator plates (22) of the inner partial package (23) are stacked such that they are twisted in opposite directions by a predetermined twist angle (γ) around the central axis (M) according to the first rotational direction of the conductor bar (6), and the stator plates (21) of the outer partial package (24) are stacked such that they are twisted in opposite directions by a predetermined twist angle (γ) around the central axis (M) according to the second rotational direction of the conductor bar (6).

12. The radial flux double rotor machine (10) according to claim 11, wherein the resulting total inclination angle (φ) in the circumferential direction of the permanent magnet (29) of the inner rotor (12) is in the range of 20% to 40% of the twist angle (γ) of the stator sheet (22) of the inner partial package (23), and / or the resulting total inclination angle (φ) in the circumferential direction 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 sheet (21) of the outer partial package (24).

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

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