In-wheel electric motor assembly with rotationally asymmetric stator, in particular for large disc brake integration

Abstract

In-wheel electric motor assembly with rotationally asymmetric stator, in particular for large disc brake integration The invention relates to an in-wheel electric motor assembly (1) for a vehicle, the assembly comprising a stator (4) being mountable to a knuckle (2) of a wheel, a rotor (3) being rotatably arranged relative to the stator (4), the rotor (3) and the stator (4) being concentrically in relation to a common axis (5), wherein the stator (4) is provided radially inwardly with a clear space (13) for accommodating components (14, 15) of a wheel assembly. For improving this to gain larger clear inner space for accommodating further components for example brakes while being a good to assemble and dismantle, it is suggested that the stator comprises an inner circumference (16) being rotationally asymmetrical relative to the common axis (5) wherein the radius (21) of the inner circumference (16) of the stator (4) relative to the common axis (5) is larger in at least some angular range (22) than in other angular ranges.

Description

[0001] In-wheel electric motor assembly with rotationally asymmetric stator, in particular for large disc brake integration

[0002] The present invention relates to an in-wheel electric motor assembly vehicle with the features cited in the preamble of claim 1.

[0003] In an in-wheel electric motor assembly of this type, as disclosed in EP 3738 192 B1 , a disc brake with a caliper and a braking disc is provided within the stator, which is mountable to a knuckle of a wheel. The dimensions are adapted in a way that the disc with the caliper properly fit within the inner circumference of the stator, which is the limitation for the clear space within which the disc brake or other components of the wheel assembly can be positioned. The disc brakes of the rear wheels usually have a smaller dimension, with their discs having a smaller diameter. This is due to the fact that the rear wheels are more prominent to traction for accelerating the wheels, while they have to transmit less braking force than the front wheels.

[0004] Due to varying inertia and the distribution of their forces on the front and rear wheels during braking and acceleration, the front wheels experience more brake force to be transmitted, so that they are usually dimensioned larger than the rear brakes. However, conventional wheel-in-wheel motors mostly provide a limited space for such components, as the arrangement of their stator and rotor need to be able to be as compact as possible in order to be integrated in a wheel rim.

[0005] Other components are, for example, conventional connecting boxes, which provide the electrical connection to the windings of the stator. Such connection boxes are usually arranged on the inner side of the stator and limit the available space for the caliper and brake discs radially. There are other components projecting inwardly, like stator mounting points, which limit the available space.

[0006] This does not only apply to brakes as such, but also to other parts, which are mostly used for having access to such an inner clear space, for example, suspension parts and steering links. All of this needs to be accommodated within a very small space, while there has to be particular attention paid to a good mountability, as well as a proper ability to disassemble or dismantle for servicing purposes.

[0007] It is the object of the present invention to improve an in-wheel electric motor assembly of the above-mentioned type, so that it provides a better, clear inner space, for accommodating further components, for example brakes, while still providing for efficient and accessible space for assembly and dismantling for maintenance and servicing purposes, and being simultaneously compact.This object is solved according to the present invention with an in-wheel electric motor assembly for a vehicle, having the features cited in claim 1.

[0008] This enlarges the potential available space and enables to use it in a more optimal manner. It adapts the inner circumference to the axial part by choosing different radii of the inner circumference of the stator, depending on where the radius should be smaller or can be made larger for accommodating particular components.

[0009] While the prior art follows the principle that the inner circular diameter of the stator limits the available room, the present invention follows the principle to adapt the inner circumference in a way that the available space allows for extensions into areas where the radius of the inner circumference could be made larger, even if it is only in some angular range. The angular range in this sense is made relative to the common axis with the rotational asymmetrical shape of the inner circumference of the stator. Actually, this design creates additional room, which was not available within the inner circumference of the stator in the prior art. In particular for disc brakes, this allows to size the diameter of disc brakes to the necessary amount and, for example, to arrange the caliper in an angular range where the radius of the inner circumference of the stator is larger than in other angular ranges. This mostly entails that the diameter of the brake disc can be made larger as well, which can be particularly beneficial at the front wheels.

[0010] According to a possible improvement of the present invention, this stator may comprise a first circular portion of its inner circumference and a second circular portion of its inner circumference, wherein the first and the second circular portions have different radii and are connected to each other by non-circular intermediate portions of the inner circumference. This enables the adaptation of the first and second circular portions to those radii which are available according to the design of the stator, where the stator needs to be provided thicker. This provides more room for accommodating parts in that angular range. The intermediate portions connect the first and the second circular portion and allow a proper transition from one radius of the one circular portion to the other radius of the other circular portion. It can be advantageous if the stator is a closed ring, regarding a proper mounting and provides more stability.

[0011] According to a further improvement of the invention, the radial thickness of the stator, in particular of its blade stack, can be made smaller in the angular range having the larger radius of the inner circumference. This allows for the use of a part of the smaller radial thickness of the stator, to provide additional space within the inner circumference, allowing for more space for arranging components. Although this may have an effect on the desired effect of the stator in the electric motor as such, this can be managed in a way that the electric motor as such still provides enoughtorque for a proper propulsion. This can be particularly chosen for the front wheels, which typically transmit less propulsion for acceleration but have to take up more braking force.

[0012] According to a further variant of the invention, the stator can be free of windings and / or free of stator teeth in the angular range having the larger radius. This enables the creation of additional space, which can be used as a clear space for accommodating components within the stator if there are less, or no windings of the stators / or the stator teeth. Although this may make the stator a bit less effective and makes the available torque and propulsion of said wheel motor a bit smaller, this can be accepted for the usage of many electric motors, for example, for front wheels which have to transmit less propulsion force but have to take up more braking forces. Surprisingly this is acceptable and can be realized with the stator not having a traditional stator design in said angular range, if it is free of windings and / or free of stator teeth or poles. In this sense it would also be acceptable if the stator has less thick windings and / or less stator teeth / poles in that angular range.

[0013] In a further modification of the present invention, a caliper of a brake can be accommodated, at least in part, in the angular range having the larger diameter. This enables to provide the caliper to be positioned a bit more radially outwardly so that this kind of bulge of the inner circumference with larger a diameter can take up a good part of the caliper. This in turn provides more space for the brake disc, whose diameter could then be increased.

[0014] A further improvement of the present invention may be if an electric connector assembly and / or a cooling fluid connector is arranged axially distanced to a brake assembly being arranged in the range of the stator. With this axial distance, the electrical connector assembly and / or the cooling fluid connector do not represent a radial space limitation for the brake assembly so that the brake components like the caliper and disc brake have more radial space to be accommodated and can have an increased / larger dimension.

[0015] It could be advantageous if the stator is provided with at least one cooling channel, in particular, integrated in the stator housing.

[0016] Although such colling channels may radially enlarge the stator, it is still possible to provide this feature with a rotational asymmetrical inner circumference of the stator.

[0017] In a possible variant of the present invention, the rotor and stator can be adapted to be connected by a locking tool assembly for mounting the rotor relative to the stator, wherein said locking tool assembly may comprises several holding fingers, being capable of being inserted radially throughthe rotor for positioning the stator relative to the rotor, at least radially. This increases the serviceability of the in-wheel electric motor assembly, and enables the proper positioning of the rotor relative to the stator although magnetic attraction forces are still present between the rotor magnets and the stator in a radial direction during servicing. The locking fingers are provided from the rotor in the radial direction for holding and thus positioning the stator relative to the rotor. If this fixation is made, other elements can be removed, for example a front plate of the rotor, which would have otherwise held the rotor and stator in the correct position relative to each other. This provides the necessary access to the inner space when needed, for example when servicing the brakes. In this state, the stator and rotor cylinder remain on the vehicle. The holding fingers could be located on the outboard side or on the inboard side, wherein inboard means in the axial direction where the remaining vehicle body is located, and outboard side means the opposite direction.

[0018] In general, the idea of holding fingers may also be realised with other in-wheel electric motor assemblies which do not have the characterising features of claim 1 , but only the features of the preamble of claim 1. It is not necessary that this principle realises the idea of a rotationally asymmetric inner circumference of the stator.

[0019] According to a variant of the invention, at least some holding fingers can be supported at the rotor and can make contact to the stator for exerting radial pushing force on the stator. This allows the holding fingers to exert the necessary pushing force for holding the stator relative to the rotor. Several such holding fingers provide the relevant positioning of the stator relative to the rotor in the desired concentric orientation while maintaining the magnetic gap, also called air gap.

[0020] According to a further improvement, at least some holding fingers can be supported at the rotor and can engage with the stator for exerting radial pulling force. This functionality of the holding fingers provide the desired pulling force which can be transferred via the holding fingers in the desired directions for maintaining the rotor relative to the stator in the desired concentrical position, while maintaining the air gap or magnetic gap sufficiently.

[0021] The aforementioned holding fingers for pulling may be designed to be able to only provide pulling force and the aforementioned holding fingers for providing pushing force may be designed to provide pushing force only.

[0022] According to an improved modification of the invention, the holding fingers providing pushing and pulling force can be distributed, preferably alternately, over the circumference of the rotor. This arrangement provides a proper rigid connection of the stator and the rotor relative to each other during servicing. It has the effect of a kind of clamping of the stator by applying pushing and pulling forces distributed over its circumference.Advantageous embodiments and modifications of the invention are explained by means of the following figures in which:

[0023] Figure 1 shows a plan view of an embodiment of the invention on the inboard side of an in-wheel electric motor,

[0024] Figure 2 shows a sectional view taken along the sectional plane ll-ll in Figure 1,

[0025] Figure 3 shows a sectional view on the plane Ill-Ill depicted in Figure 2,

[0026] Figure 4 is an enlarged sectional view of the upper left corner in Figure 2 in one angular position, and

[0027] Figure 5 shows an enlarged sectional view of the left upper corner of Figure 5 in a different angular position than Figure 4.

[0028] The invention will be described in the following by means of the figures and this embodiment, wherein same reference numerals in the Figures depict the same parts and refer to the same feature, unless differently described in the following description.

[0029] Figure 1 shows an in-wheel electric motor assembly 1 as seen from the inboard side, which means from the side where the vehicle is and where the in-wheel electric motor assembly can be mounted to a knuckle 2 of a vehicle. Such electric motor assemblies are mostly synchronous electric motors and brushless direct current motors. In Figure 2, the position of the knuckle 2 has been principally added for clarification purposes.

[0030] The motor comprises a rotor 3, which is rotatably mounted around a stator 4. Both are concentrically positioned relative to each other in relation to a common axis 5, which would be the rotational axis of a wheel of a vehicle. In Figure 1 , the common axis is at the center point of a symmetry line 6 and a symmetry line 7, which are perpendicular to each other. The symmetry lines 6 and 7 are shown in solid lines, although they would be rather shown in dash-dotted lines in pure technical workshop drawings.

[0031] The rotor 3 has a circular shape with the axis 5 being the center point in Figure 1 , and is rotation-ally symmetrical with regard to it.

[0032] The stator 4 comprises a stator housing 8 and outwardly thereof a stator ring 9. Further, it comprises radially outwardly a stator yoke 10 comprising a blade stack 11. The blade stack 11 comprises stator teeth 12 extending radially outwardly. The stator teeth 12, sometimes also called stator poles depending on the kind of electrical motor, are capable that typical stator windings forproducing the magnetic field are wound around them. These stator windings are not shown in the drawing for illustrative purposes.

[0033] Inside the stator 4 is a clear space 13 in which components can be accommodated. In the present case, a circular brake disc 14 provided with a brake caliper 15 are provided within the stator. The brake disc is rotatable about the common axis 5. The caliper is shifted to one side close to the stator ring 9, as it has to extend over the brake disc for being able to clamp the brake pads to the brake disc on both flat sides of the brake disc 14, so the caliper 15 requires additional space around the outer circumference of the brake disc 14 between the brake disc and the stator 4.

[0034] The stator 4 is not a circle but has an inner circumference 16, which is rotationally asymmetrical in relation to the common axis 5.

[0035] In the right half of Figure 1 on the right side of the symmetry line 6, the stator has the shape of a part of a circle, preferably a half circle, concentrically arranged to the circular shape of the rotor 3 in that angular range. Said half circle has a first inner radius 17 relative to the common axis 5. Said part of the circle of the stator represents a first circular portion 18.

[0036] Adjacent to that first circular portion extend intermediate portions 19 starting from the ends of the circular portions, approximately from the symmetry line 6 to the left side in Figure 1. These two intermediate portions are approximately straight, which means that they do not keep the same first inner radius 17 but have an orientation so that they form a transition portion, gradually widening the inner radius as measured relative to the common axis 5. The intermediate portions 19 with the straight portions extend a small distance up to the dashed lines indicated in Figure 1. From said dashed lines, the stator 4 continues with a second circular portion 20 connecting the two intermediate portions 19. The first and the second circular portions 18, 20 together with the intermediate portions 19 of the stator from a closed ring.

[0037] The second circular portion 20 is circular relative to the common axis 5 and to most of its extent, concentrically to the circular shape of the rotor 3. The second circular portion 20 has a second inner radius 21 , starting from the common axis 5, which is larger than the first inner radius 17 of the first circular portion 18. This means that the space 13 within the stator on this left side of the symmetry line 6 is larger than the space on the right side in Figure 1 where the first circular portion 18 with a smaller first inner radius 17 is. The second circular portion 20 extends along an angular range 22, the sector of which being depicted in dashed lines in Figure 1.

[0038] The stator teeth 12 are only provided in a portion of the stator 4, in this case in the first circular portion 18. In Figure one, they are provided in an angular range of about 180 degrees of the firstcircular portion 18. The remaining circumference of the stator 4 extending to the left side of the symmetry line 6 in Figure 1 is not provided with blade teeth but only the stator yoke extends into that side with its stator ring 9. In the intermediate portion the distance from the stator relative to the rotor gradually becomes smaller until the stator comes very close to the rotor 3 and by its second circular portion 20.

[0039] There remains an air gap 35, also called magnetic gap, between the stator 4 and the rotor 3 over the entire circumference of the stator 4. The stator is formed so that the thickness of the air gap 35 is approximately constant over the entire circumference. This means that the outer circumference of the stator 4 remains circular.

[0040] As becomes apparent from the above, the radial thickness of the stator 4 is smaller in the angular range 22 of the second circular portion. This is, in particular, because the stator ring is made radially smaller in that range, preferably as the blade stacks teeth are removed. The intermediate portion 19 / the stator yoke 10 radially diminishes the thickness of the stator 4 from the full thickness in the first circular portion 18 to the small thickness in the second circular portion 20. Thus, the stator 4 also does not have windings in the area without the stator teeth 12.

[0041] The caliper 15 is arranged radially inwardly within the second circular portion 20 of the stator 4 having the larger second inner radius 21. Thus, the caliper 15 is positioned more radially outwardly, as if it was arranged at the side of the first circular portion 18 having the smaller first inner radius 17. With this arrangement of the caliper 15, the brake disc 14 can be made larger, having a larger diameter, than if the caliper 15 was provided in the first circulare portion 18 having the smaller first inner radius 17.

[0042] Figure 1 shows that the stator 4 is provided with four mounting points 23, extending inwardly and being evenly distributed about the circumference of the stator 4. These mounting points 23 are for mounting the electric motor assembly 1 to a knuckle 2 of a vehicle. The knuckle 2 is shown schematically in Figure 2. As apparent from Figure 1, the mounting points 23, which extend a bit flange-like, or like fingers, inwardly, overlap radially with the brake disc 14, as well as with the caliper 15.

[0043] In a similar manner, a connection box 24, with three electrical connections 25, which are depicted as circles within the connections box 24, are provided integrally with the stator housing 8. The connection box 24 also extends radially inwardly and overlaps radially with the brake disc 14. The electrical connections 25 serve for connecting the windings of the stator 4 to the current delivered by the vehicle.As can be seen in Figure 2, the connection box, serving as an electrical connector assembly, is provided axially distanced to the brake disc 14, as seen in the axial direction, so that there is an axial distance between both. This allows the brake disc 14 to be made gradually larger without impeding with the connection box 24.

[0044] As can be seen in Figure 2, the stator 4 is provided with cooling channels 26, which are formed in between the stator housing 8 and the stator ring 9. There are two flat cooling channels 26, which run all around the circumference of the stator 4. The follow the rotationally asymmetrical shape of the inner circumference of the stator 4 about the circumference. The cooling channels 26 can be connected with the cooling fluid supply via the connection box 24.

[0045] Radially outside of the stator ring 9 are the stator teeth 12.

[0046] Figure 2 shows the rotor 3 with a cylindrical rotor housing 27, extending circumferentially around the stator 4. The rotor housing 27 carries magnets for interacting with the blade stack 11 and the winding of the stator 4.

[0047] The rotor 3 further comprises a rotor plate 28, mostly radially and approximately perpendicularly extending from the cylindrical rotor housing 27. The detachable rotor plate 28 is fixed to the rotor housing 27 by means of screws or the like, which are not shown. The rotor plate serves for rotatably mounting the rotor 3 to a shaft or axle on the common axis 5. Such a shaft or axle connection is mostly extending directly from the knuckle 2 and allows the rotation of the rotor 3 around the common axis 5 and the stator 4. The rotor 3 also carries the wheel rim of a vehicle wheel, which is not shown.

[0048] The principle that the rotor 3 comprises a separate, detachable rotor plate 28, serves the purpose to gain acces to the interior of the rotor 4, for example for servicing, and can principally be realised also with other in-wheel electric motor assemblies, independent of the further particular features of the embodiment shown in the figures. In this case, the rotor housing 27 may be positioned relative to the stator 4 if the rotor plate 28 is removed, and this can be realised by various positioning means, also being different to the ones shown in the figures.

[0049] While the caliper is usually fixed to the stator 4, the brake disc 14 is usually fixed to the rotor 3 or at least a part rotatable with the rotor 3.

[0050] Figure 3 shows a sectional view on the sectional plane ll-ll in Figure 1 and it should be referred to the corresponding explanations regarding this design, as made for Figures 1 and 2.Figures 4 and 5 basically show a cross section of the portion of the top left corner of Figure 2 but at different rotational positions around the common axis 5.

[0051] Figure 2 schematically shows a hole 29 in the rotor housing 27 extending radially through it and in direction to a portion of the stator housing 8. There are several such holes distributed in even distances angularly over the circumference of the cylindrical rotor housing 27.

[0052] Figure 4 shows one of these holes 29 through which a threaded bolt 30 extends. The hole 29 at this angular position is threaded so that the bolt can engage it. The flat front surface of the threaded bolt 30 abuts against a holding flange 31 of the stator housing 8 and exerts a radial pushing force on the stator 4. Several such arrangements using the threaded bolts being in abutment with the holding flange 31 are distributed over the circumference of the rotor.

[0053] Figure 5 shows a similar arrangement but at different angular positions. The hole 29 in that case is a through hole for a threaded bolt 32, which is provided with a thread only at its end and has a non-threaded cylindrical portion close to the head of the bolt. The hole 29 is either non-threaded, or at least large enough that the bolt passes through it. The threaded end engages with a threaded hole 34 in the holding flange 31 of the stator housing 8. The threaded bolt 32 is threaded into said hole 34 to the extent that the head of the bolt supports on the outside of the rotor housing 27 and exerts a pulling force onto the stator 4. Several such arrangements are distributed angularly about the circumference of the rotor 3, so that the stator 4 can be held by such pulling forces in its radial position relative to the rotor 3 so that the air gap in between the rotor 3 and the stator 4 of an electric motor is maintained.

[0054] In some embodiments the arrangements of Figure 4 and Figure 5 providing the pulling force and the pushing force in a radial direction are alternately distributed over the circumference of the rotor 3.

[0055] The arrangement of Figure 4, as well as of Figure 5, similar to the mentioned combination of alternating positions of Figures 4 and 5, each provide a locking tool assembly in which the threaded bolts 30, 32present holding fingers for positioning the stator 4 relative to the rotor 3.

[0056] With the aforementioned possibility to use larger components within the space 13 of the stator 4, like the larger brake disc 14, but also with the caliper 15 being shifted more radially outwardly within said second circular portion 20, there is an axial overlap of these components with, for example, the stator mounting points or the connecting box 24. Further, the electric motor cannot be easily accessed from the knuckle 2 side. Thus, the servicing of, and maintenance of interior parts is done by splitting the rotor 3 into the cylindrical rotor housing 27, and the rotor plate 28,and enabling that the rotor plate 28 can be taken off the rotor housing 27. In order to do so, the critical air gap or magnetic gap between the rotor 3 and the stator 4 needs to be maintained. This is done by previously using the aforementioned holding fingers, e.g. by use of the threaded bolts exerting the pushing forces and / or the threaded bolts 32 exerting the pulling forces. This enables the proper radial position of the stator relative to the rotor.

[0057] This positioning needs to be done prior to removing the rotor plate 28, as the rotor plate 28 serves for a proper radial position of the cylindrical rotor housing 27 without such holding fingers. Dismounting the rotor plate 28 then provides sufficient access to the internal components within the stator 4 for maintenance and servicing.

[0058] The asymmetric arrangement with the larger radius of the inner circumference at least over a particular angular range creates more space within the stator 4 for accommodating parts therein. This is in particular advantageous for using larger discs and enabling to arrange the caliper 15 in this gained space. For vehicles, this solution is particularly beneficial for the front wheels, which have to take up more braking force but have to produce less propulsion force due to the change of the inertia forces between acceleration and deceleration of a vehicle.

[0059] A part of the stator 4 is no longer provided with the traditional bladestack and windings. The remaining rotational force created by the motor is still sufficient for the front wheels. Surprisingly, this can be attained by using a rotationally asymmetric stator. While the prior art continuously used concentric circular arrangements of rotor and stator, the present invention deviates from said principle, and renders more internal space for components within the stator 4, while still providing a sufficiently effective electric motor.

[0060] The stator 4, in particular the blade stack 11, is usually a laminated part, which is mounted over the stator ring 9, for example by press fitting. The press fit provides good thermal contact and torque transfer based on friction. A press fit can be obtained during the assembly of the blade stack 11 and the stator ring 9 with the housing 8, where one is cooled down and the other is heated. The temperature difference causes the parts to have slightly different diameters so that the assembly process can be carried out by inserting the cold part into the hot one. After thermal relaxation, both parts are stuck together with high forces acting in the radial direction. In on variant of the present embodiment, the process is repeated separately for the stator housing 8 and the stator ring 9, then with the stator housing / ring 8,9 and the blade stack 11. In another variant of the present embodiment, there may be only one press-fitting-process by cooling and heating, for example by applying intermediate temperature levels for specific parts or having some adjacent parts already preassembled before conneting them to the other parts by press-fitting. For all theseprocesses, the resulting static load provides for both good thermal contact and enough friction so that all of the motor torque can be transferred from the windings to the knuckle 2.

Claims

CLAIMS1. An in-wheel electric motor assembly (1) for a vehicle, the assembly comprising a stator (4) being mountable to a knuckle (2) of a wheel, a rotor (3) being rotatably arranged relative to the stator (4), the rotor (3) and the stator (4) being concentrically in relation to a common axis (5), wherein the stator (4) is provided radially inwardly with a clear space 13 for accommodating components (14, 15) of a wheel assembly, characterized in that the stator (3) comprises an inner circumference (16) being rotationally asymmetrical relative to the common axis (5), wherein the radius (21) of the inner circumference (16) of the stator (4) relative to the common axis (5) is larger in at least some angular range (22) than in other angular ranges.

2. In-wheel electric motor assembly according to claim 1 , characterized in that the stator (4) comprises a first circular portion (18) of its inner circumference and a second circular portion (20) of its inner circumference, wherein the first and the second circular portion (18, 20) have different radii (17, 21) and are connected to each other by non-circular intermediate portions 19 of the inner circumference 16.

3. In-wheel electric motor assembly according to one of claims 1 or 2, characterized in that the radial thickness of the stator 4, in particular of its blade stack, is smaller in the angular range (22) having the larger radius (21) of the inner circumference.

4. In-wheel electric motor assembly according to any of the aforementioned claims, characterized in that the stator (4) is free of windings and / or free of stator teeth (12) in the angular range (22) having the larger radius (21).

5. In-wheel electric motor assembly according to any of the aforementioned claims, characterized in that a caliper (15) of a brake is accommodated at least in part in the angular range (22) having the larger radius (21).

6. In-wheel electric motor assembly according to any of the aforementioned claims, characterized in that an electric connector assembly (24, 25) and / or a cooling fluid connector is arranged axially distanced to a brake assembly (14, 15) being arranged in the range of the stator (4).

7. In-wheel electric motor assembly according to any of the aforementioned claims, characterized in that the stator (4) is provided with at least one cooling channel (26), in particular being integrated in the stator ring / housing (8,9).

8. In-wheel electric motor assembly according to any of the aforementioned claims and being adapted to be connected by a locking tool assembly (30, 32) for mounting the rotor (3) relative to the stator (4), characterized in that the locking tool assembly (30, 32) comprises several holding fingers (30, 32) being capable of being inserted radially through the rotor (3) for positioning the stator (4) relative to the rotor (3) at least radially.

9. In-wheel electric motor assembly according to claim 8, characterized in that at least some holding fingers (30) are supported at the rotor (3) for exerting radial pushing force on the stator (4).

10. In-wheel electric motor assembly according to claim 8 or 9, characterized in that at least some holding fingers (30, 32) are supported at the rotor (3) and engage with the stator (4) for exerting radial pulling force.

11. According to at least one of claims 8 to 10, characterized in that the holding fingers (30, 32) providing pushing and pulling force are distributed, in particular alternately, over the circumference of the rotor (3).

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