EP2178736A2

EP2178736A2 - External-rotor electric motor with or without a planetary gear mechanism, motor vehicle with an external-rotor electric motor and a method for operating such a vehicle

Info

Publication number: EP2178736A2
Application number: EP08789364A
Authority: EP
Inventors: Rudolf Hoebel; Robert Haas; Michael Hörmann
Original assignee: Clean Mobile AG
Current assignee: Clean Mobile AG
Priority date: 2007-07-18
Filing date: 2008-07-18
Publication date: 2010-04-28
Also published as: WO2009010943A3; JP2010534051A; AU2008277325A1; DE202008018341U1; EP2178736A4; CN101855123A; WO2009010943A2; US20100263959A1

Abstract

An electric motor (25) according to the invention for a motor vehicle has a stator (1) with predetermined areas (4) for connection to a vehicle frame, wherein the stator (1) can be connected to the vehicle frame by welding or by screwing, for example. The electric motor (25) according to the invention also has a rotor (13), wherein the rotor (13) can be arranged on a drive shaft (17) which is rotatably mounted in the stator (1). The electric motor (25) is embodied as an external rotor motor and has a planetary gear mechanism (26).

Description

description

External rotor electric motor with or without planetary gear, motor vehicle with external rotor electric motor and method of operating such a vehicle

The invention relates to an external rotor electric motor with an optional planetary gear for a motor vehicle, in particular for a bicycle with electric drive. It further relates to a motor vehicle with such an external rotor electric motor and a method for operating such a vehicle.

[2] Bicycles with an electric motor as an auxiliary drive usually have a first

Drive means such as a chain, which transmits the torque provided by the driver via pedals from a front sprocket to a rear sprocket and thus to the wheels, and a second drive means which transmits the torque provided by the electric motor to the wheels of the vehicle.

US 5,570,752 A discloses a bicycle with an electric motor having a relatively complicated and expensive gear construction for transmitting the torque of the electric motor.

From DE 195 22 419 Al is a bicycle with a brushless

Disc rotor motor formed electric motor known, the front sprocket is designed as a permanent magnet and forms the rotor of an electric motor. In the area of the bottom bracket, a stator disk is clamped with windings, which acts on the permanent magnet.

A disadvantage of this arrangement is that support pins must be provided to support the torque against the vehicle frame for a robust operation of the vehicle. Furthermore, the sprocket is expensive and heavy by the design as a permanent magnet and the electrical efficiency is low.

[6] Further documents are DE 196 29 788 A1, U 3 884 317 A, GB 2 414

452 A, DE 196 21 440 A1, EP 0 258 041 A2, EP 0 590 674 A1, DE 195 22 419 A1, DE 44 21 428 C1, US Pat. No. 5,570,752 A, US Pat. No. 6,629,574 B2 and DE 100 26 528 A1. All of these documents are not relevant to the subject matter of the claims.

[7] The object of the invention is to provide a lightweight and compact vehicle with electric motor drive, which at the same time has a simple and robust construction and good efficiency.

According to the invention this object is achieved with the subject matter of the independent

Claims solved. Advantageous developments of the invention are the subject of the dependent claims. [9] An electric motor for a motor vehicle according to the invention has a stator with at least one or more predetermined areas for connection to a vehicle frame, wherein the connection of the stator to the vehicle frame can be made, for example by welding or screwing, and the areas provided for connection are designed appropriately suitable. The electric motor according to the invention further comprises a rotor and predetermined areas for receiving a drive means. The electric motor is designed as an external rotor motor and has a planetary gear.

In this case, the rotor may also be part of the planetary gear or be integral with a part of the planetary gear.

[11] The external rotor motor has a radial construction of a central shaft, which is mounted in a bearing receptacle of the stator. In the radial direction, the electromagnets of the stator, which have ferromagnetic yokes with windings, adjoin the bearing mount, wherein the windings are arranged such that their longitudinal axis is radially aligned and thus they also generate a magnetic field which is also radially aligned. In turn, a plurality of permanent magnets of the rotor, which are arranged on the inside of a ring surrounding the stator and which lie opposite the yoke terminations, adjoin the yoke terminations of the yokes in the radial direction.

In one embodiment, the rotor is arranged on a drive shaft, which in the

Stator is rotatably mounted. This embodiment is particularly suitable when the electric motor is provided for installation in a bicycle. In this case, cranks with pedals can engage the drive shaft and the electric motor according to the invention has the advantage that it can be integrated into the frame to save space in the bottom bracket and can be formed as an integral part of the vehicle frame and thus robust and very stable.

If the electric motor is provided for installation in a motorcycle or motorcycle, which has no arranged on a crank pedals for the driver, there is on the one hand the possibility to provide an optionally shortened drive shaft on which, for example, a pinion for receiving a chain, a cardan pinion for receiving a cardan shaft or a pulley for receiving a toothed belt is mounted. On the other hand, there is also the possibility not to provide a drive shaft, but to connect a predetermined area for receiving a drive means, so a pinion or a pulley, directly to parts of the planetary gear. Also in this embodiment, the electric motor according to the invention can be designed as an integral part of the frame and thus particularly stable.

For example, the stator with frame tubes of the vehicle, in particular a Bike or motorcycle, bolted or welded. A separate support of the torque is thus not required.

Furthermore, the electric motor according to the invention has the advantage that it can be made relatively compact and compact due to the favorable geometry of the electric motor, which provides a plurality of small permanent magnets instead of a massive disc. External rotor motors have a relatively large moment of inertia, which has a very advantageous effect on the smooth running of the vehicle in the present application.

[16] The planetary gearbox can be used for over or under gear reduction. It can also be provided a switchable planetary gear. In particular, it may be possible to simultaneously transmit both the torque caused by a rider pedaling and the torque provided by the electric motor to the wheels of the vehicle, although the rider's pedaling frequency is different from the frequency of the electric motor. This makes it possible, despite a normal cadence of the driver to operate the electric motor in a frequency range which has a particularly high efficiency or otherwise favorable. In general, the engine is operated at a much higher frequency than the cadence of the driver.

[17] Various embodiments of the planetary gear are conceivable. In a

Embodiment, a web of the planetary gear is fixedly connected to the stator of the electric motor. It is either possible that the ring gear of the planetary gear is fixedly connected to the rotor or that the sun gear of the planetary gear is fixedly connected to the rotor.

In another embodiment, the sun gear of the planetary gear is fixedly connected to the stator. In this embodiment, either the ring gear or the web of the planetary gear is fixedly connected to the rotor. In this embodiment, the drive shaft, if it is present, advantageously stored in a hollow shaft.

[19] In another embodiment, the ring gear of the planetary gear is fixedly connected to the stator. In this case, either the sun gear or the web of the planetary gear is firmly connected to the rotor.

[20] In a preferred embodiment, the electric motor is designed as an electronically commutated DC external rotor motor. Energy storage such as batteries for operating the electric motor can be provided in the region of the rear wheel or behind a driver's seat. In this embodiment, the electric motor is brushless and the rotor has a number of Permament- magnets on. Brushless electric motors have the advantage that they have a longer life and a higher efficiency than those with a brush system. By avoiding the so-called brush fire, a reduction of high-frequency electromagnetic interference is achieved.

[21] The areas for receiving a drive means are designed, for example, as a sprocket rim or as a toothed belt pulley. Preferably, the areas for receiving the drive means are firmly screwed to the drive shaft or to areas of the planetary gear.

[22] Cranks with pedals can be attached to the ends of the drive shaft in one embodiment. The electric motor is thus integrated into the bottom bracket of the bicycle or parts of the electric motor form the bottom bracket, and the electric motor and moved by the force of the driver pedals attack on the same shaft. As a result, the electric motor according to the invention is particularly simple and compact.

In an advantageous embodiment, the drive shaft in a

Transition region to the rotor on a freewheel device. This has the advantage that a rolling of the vehicle is possible even without a simultaneous rotation of the drive shaft, so that the driver does not have to constantly kick. The freewheel is therefore expediently provided when the electric motor is used for a bicycle.

[24] In one embodiment, the rotor has a diameter D of 250 mm <

D <350 mm. The height h of the rotor is for example 30 mm <h <60 mm. Thus, the electric motor is compact enough to be arranged in the region of the bottom bracket between the pedal cranks of the vehicle and thus also approximately in the center of gravity of the vehicle.

An inventive motor vehicle, for example a bicycle with an electric motor or a motorcycle, has the electric motor according to the invention, wherein the stator of the electric motor is connected to frame tubes of the motor vehicle and a drive shaft is connected by a drive means with a wheel of the motor vehicle. The stator may be welded or bolted to frame tubes of the vehicle. In any case, it is stably connected to the vehicle frame and thus does not require torque support against the bicycle frame.

[26] Advantageously, the pinion gear is fixedly connected to the drive shaft and either to the web or the sun gear or the ring gear of the planetary gear.

On the ends of the drive shaft cranks are in one embodiment with

Attached pedals. Thus, the electric motor can be mounted in the region of the bottom bracket of a bicycle and replace it, the engine and the driver attack on the same drive shaft.

[28] An inventive method for operating a motor vehicle with a than

External rotor motor trained electric motor with a planetary gear has The following steps are provided: A stator of the electric motor is provided with windings for generating magnetic fields in the radial direction, the windings having connections for a supply voltage. In addition, a rotor of the electric motor is provided with permanent magnets, wherein the permanent magnets are arranged so that they are opposite to the windings with respect to a rotational axis of the rotor in the radial direction. The supply voltage is switched such that the magnetic field generated by the current-carrying windings exerts an attractive force on the permanent magnets of the rotor and thus a torque on the rotor.

[29] For switching the supply voltage is advantageously an electronic

Commutator used so that the electric motor can be performed brushless. The supply voltage is triggered for example by a Hall sensor or by evaluating induction currents in the windings. In this way, a very accurate triggering of the supply voltage is ensured, so that even high speeds of the electric motor are possible.

[30] One of the several ideas underlying the invention involves that

Carrying areas of the stator, the z. B. may be formed as a plate or a grid plate, constitute an integral or self-supporting component of the vehicle frame. As a result, the electric motor according to the invention can be integrated particularly well and simply in a vehicle. Unlike in the prior art, where cumbersome additional components must be provided, the electric motor according to the invention fits into a frame concept, wherein advantageously in a particular embodiment, an output shaft of the electric motor can be designed as a bottom bracket, for example, for a vehicle driven by cranks.

If a rear suspension for the vehicle by means of a rocker is provided, as is customary for example in motorcycles, the electric motor according to the invention is advantageously arranged such that its axis of rotation, which is called the axis of rotation of the rotor or the drive shaft, with the axis of rotation Swing arm coincides or at least closely in their range. In this case, the arms of the rocker may also attack on both sides of the vehicle on the drive shaft.

With the existing design and electric motors with much higher efficiency than in the prior art can be provided.

[33] In one embodiment, permanent magnets arranged radially on the circumference of the rotor can be provided, which are subjected to an electromagnetic force by the likewise radially provided coils of the stator. Radially provided on the circumference of permanent magnets and corresponding yokes of electromagnets are particularly proven, because in these the gap width only to a very small extent fluctuates, which provides high efficiency. In the electric motors known in the prior art, the gap width between stator and rotor is subject to significantly greater fluctuations.

[34] The embodiments of the invention are described essentially with permanent magnets on the rotor and with electromagnetic coils on the stator. It is also possible to provide permanent magnets on the stator and to operate them with electromagnets on the rotor, which means a higher circuit complexity. In addition, electromagnets can be provided both on the stator and on the rotor without departing from another idea underlying the invention.

[35] Embodiments of the invention will be described below with reference to the attached

Figures explained in more detail.

[36] Figure 1 shows schematically a plan view of the stator of an inventive

Electric motor for a bicycle according to a first embodiment;

[37] Figure 2 shows schematically a plan view of the rotor of an inventive

Electric motor;

[38] Figure 3 shows schematically a cross section through the rotor of an electric motor according to the invention;

[39] FIG. 4 shows schematically a cross section through the electric motor according to the invention according to the first embodiment;

[40] FIG. 5 shows schematically a plan view of the stator of a device according to the invention

Electric motor according to a second and third embodiment of the electric motor according to the invention;

[41] Figure 6 shows schematically a cross section through a second embodiment of the electric motor according to the invention;

FIG. 7 shows schematically a cross section through a third embodiment of the electric motor according to the invention and FIG

[43] Figure 8 shows schematically a cross section through an alternative embodiment of the electric motor according to the invention.

[44] Figures 1 to 4 show schematically an electric motor according to a first

Embodiment of the invention.

The stator 1 of the external rotor electric motor according to the invention, which is shown schematically in plan view in FIG. 1, comprises a plate 2, which in this embodiment is an integral part of the frame of a bicycle (not shown in detail) of which in FIG Sections of three frame tubes 3 are shown. The plate 2 has at its outer edge areas 4, which are provided for attachment to the frame tubes 3. Each region 4 is formed in this embodiment as a rectangular flange.

The plate 2 of the stator 1 has inside a bearing holder 8 with a ball bearing 12 on. The ball bearing 12 comprises an outer ring 9, an inner ring 11 and arranged between the outer ring 9 and the inner ring 11 balls 10. The inner ring 11 encloses an opening 24 having a diameter <X. The opening 24 is provided for receiving a drive shaft, not shown in the figure 1. For example, <X can be 20 mm.

[47] The bearing seat 8 of the stator 1 is enclosed by the base ring 5, which the

Yoke 6 of the stator 1 carries. The yokes 6 are each provided with windings 7, which are supplied via here only schematically shown leads 23 with power. The yokes 6 with the windings 7 extend radially from the base ring 5 to the outside and have radially adjoining the windings 7 Jochabschlüsse 34. The yoke ends are also adjoined in the radial direction by a running region 35 for the rotor of the electric motor (not shown in FIG. 1).

[48] Only a few yokes 6 are shown in the figure. For a quiet running of the

Fahrrads and to provide a high torque, however, a much larger number of yokes 6 with windings 7 is provided.

[49] Figure 2 shows schematically a plan view of the rotor 13 of the invention

The electric motor. The rotor 13 has a pot shape with a bottom 14 and an edge 15. The rotor 13 has a diameter D of 250 mm <D <350 mm.

[50] On the inside 26 of the rim 15, a plurality of permanent magnets 16 is arranged. The permanent magnets 16 are arranged such that their polarity changes in the direction of the circumference of the rotor 13, which is indicated by the arrow 36.

The rotor 13 is fixed in this embodiment on the drive shaft 17 of the

Bicycle arranged, it can also be designed in one piece with the drive shaft 17. The drive shaft 17 has a diameter d _a , which may be 20 mm, for example. The drive shaft 17 has at each of its ends square connections 18 for attachment of a crank 19 for a pedal 20. The pedals are fastened to the cranks 19 by means of a fastening element 21 such as a screw.

FIG. 3 shows a cross section through the rotor 13. In this illustration, it can be seen that the rotor 13 has a height h, which is typically 30 to 60 mm.

[53] In this illustration it can also be seen that the rotor 13 is in the region of its bottom

14 has a sprocket ring 22 for receiving a chain, not shown. The sprocket ring 22 can be screwed to the bottom 14 of the rotor 13 in this embodiment. For this purpose threaded holes 27 are provided.

FIG. 4 schematically shows a cross section along the line AA from FIG. 1, wherein not only the stator 1 but also the rotor 13 are shown in this illustration is. The rotor 13 is arranged such that the drive shaft 17 extends through the opening 24 in the inner ring 11 of the ball bearing 12 and is mounted by means of the ball bearing 12 shown only symbolically in this figure. In this case, the diameter d of the central hole 24 substantially corresponds to the diameter d _{a of} the drive shaft 17.

[55] The equipped with the permanent magnet 16 edge 15 of the rotor 13 is in the

Running region 35 of the stator 1, which adjoins in the radial direction of the yoke terminations 34 of the stator 1. The permanent magnets 16 of the rotor 13 are the high ends 34 of the yokes 6 with the windings 7 opposite.

For mounting the electric motor according to the invention proceeds as follows: The plate 2 of the stator 1 is connected in the designated areas 4 with the frame of a bicycle, in which he, for example, as shown in this embodiment, welded to the frame tubes 3. Subsequently, the ball bearing 12 is mounted in the bearing receptacle 8 and the yokes 6 with the yoke terminations 34 and the windings 7 are connected to the base ring 5 with the bearing receptacle 8.

[57] Further, the rotor 13 is provided with the permanent magnets 16 attached to the inside 26 of its rim 15. The rotor 13 is inserted into the pot-shaped in this embodiment stator 1 and connected thereto by inserting the drive shaft 17 in the opening 24 in the inner ring 11 with the ball bearing 12. In this case, the edge 15 comes to rest with the permanent magnets 16 in the running region 35 of the stator 1. Finally, the cranks 19 are mounted with the pedals 20 on the drive shaft 17.

[58] It is also possible to first assemble the electric motor 25 into the stator 1 by inserting the rotor 13 and only then to connect it to the frame tubes 3. This is particularly possible if the connection of the plate 2 of the stator 1 with the frame tubes 3 by screwing and not by welding.

[59] In operation, the windings 7 are traversed by an electric current and provide a magnetic field which generates a torque by the interaction with the permanent magnets 16 of the rotor 13. For this purpose, the voltage supplying the current through the windings is switched at each moment so that the permanent magnets 16 are attracted to the yoke terminus 34 following in the direction of the circumference of the rotor 13, while they are repelled by the yoke terminus 34 that has just passed.

[60] An electronic commutator can be used to switch the supply voltage for the windings (7). The triggering of the voltage succeed, for example, contactless by a Hall sensor or by evaluating Induction currents in the windings.

The torque is transmitted via the fixedly mounted on the rotor 13 pinion ring 22 by means of a chain not shown on the wheels of the bicycle. In one embodiment, not shown, a toothed belt pulley is provided instead of the pinion ring and instead of a chain, a toothed belt.

[62] However, the bicycle with the electric motor 25 according to the invention can additionally be driven by the driver via the pedals 20 mounted on the drive shaft 17. Both the electric motor 25 and the pedals 20 thus act on the same drive shaft 17 and therefore require only a single, common chain or a toothed belt to transmit the torque.

[63] Figure 5 shows a schematic plan view of a second or third

Embodiment of the stator 1 of the electric motor according to the invention. In these embodiments, the plate 2 of the stator 1 is not welded directly to the frame tubes 3. Instead, 3 holding plates 28 are welded to the frame tubes, which are indicated in Figure 5 only by dashed lines. Instead of separate retaining plates 28 for each frame tube 3, a common retaining ring 31 may be provided, which is also indicated by dashed lines in Figure 5, or another type of common mounting plate. In this case, a common retaining ring 31 or a differently shaped common retaining plate has the advantage that the frame of the bicycle is also connected without the electric motor and is self-supporting.

[64] The plate 2 of the stator 1 has areas 4 for attachment to the holding plates 28 or the holding ring 31 of the frame, the areas 4 being formed as plates in this embodiment and having holes 29 for receiving fasteners such as screws.

[65] FIG. 6 shows the electric motor 25 according to FIG. 5 in cross section along the line

A-A. Shown is the second embodiment, in which the plate 2 of the stator 1 is fixed in their areas 4 on separate holding plates 28 of the frame tubes 3.

[66] The third embodiment of the electric motor 25 with a common retaining ring

31 is shown schematically in cross section in FIG. The retaining ring 25 is fixed to the plate 2 of the stator 1 like the retaining plates 28 in the second embodiment. For receiving fasteners such as screws in turn holes 29 are provided.

[67] FIG. 8 shows an alternative embodiment of the electric motor 25 schematically in FIG

Cross-section. In this embodiment, the rotor 13 has a freewheel device 33 with locking blades or pinch rollers. This embodiment has the advantage that a constant pedaling of a driver is not required. In this embodiment, it is because of the freewheel 33 for the driver is not necessary to constantly operate the pedals, but the rotation of the drive shaft 17 can also by the movement of the Rotor 13 are disconnected, so that a drive of the bicycle takes place solely on the electric motor 25 without the assistance of the driver.

[68] In the above-described embodiments, the following reference numerals have been used

[69] 1 stator

[70] 2 plate

[71] 3 frame tube

[72] 4 areas

[73] 5 base ring

[74] 6 yoke

[75] 7 windings

[76] 8 bearing support

[77] 9 outer ring

[78] 10 bullets

[79] 11 inner ring

[80] 12 ball bearings

[81] 13 rotor

[82] 14 soil

[83] 15 edge

[84] 16 permanent magnet

[85] 17 Drive shaft

[86] 18 square connection

[87] 19 crank

[88] 20 pedals

[89] 21 fastener

[90] 22 sprocket wheel

[91] 23 supply line

[92] 24 Opening in the inner ring

[93] 25 electric motor

[94] 26 inside

[95] 27 threaded hole

[96] 28 retaining plate

[97] 29 holes

[98] 31 retaining ring

[99] 33 freewheel device

[100] 34 yoke conclusion

[101] 35 Running range

[102] d _a outer diameter of the crank [103] (I ₁ inner diameter of the central hole

[104] D diameter of the rotor

[105] h height of the rotor

[106] The embodiments may also be described with the following listings of

Characteristics are described in paragraphs 1 to 20, with particular reference to the combinations of features resulting from back references:

[107] An electric motor (25) for a motor vehicle, comprising:

[108] - a stator (1) having predetermined areas (4) for connection to a vehicle frame;

[109] - a rotor (13) having predetermined areas for receiving a drive means, the rotor (13) being disposed on a drive shaft (17) rotatably supported in the stator (1);

[110] - the electric motor (25) is designed as an external rotor motor.

[111] 2. electric motor (25) according to point 1,

[112] wherein the electric motor (25) is designed as an electronically commutated DC external rotor motor.

[113] 3. electric motor (25) according to item 1 or 2,

[114] wherein the electric motor (25) is brushless and the rotor (13) comprises a number of permanent magnets (16).

[115] 4. electric motor (25) according to one of the items 1 to 3,

[116] wherein the areas for receiving a drive means as a sprocket rim (22) is formed.

[117] 5. Electric motor (25) according to one of the numbers 1 to 3,

[118] wherein the areas for receiving a drive means is designed as a toothed belt pulley.

[119] 6. Electric motor (25) according to one of the items 1 to 5,

[120] wherein cranks (19) with pedals (20) can be fastened to the ends of the drive shaft (17).

[121] 7. Electric motor (25) according to one of the numbers 1 to 6,

[122] wherein the areas for receiving the drive means are screwed to the rotor (13).

[123] 8. Electric motor (25) according to one of the numbers 1 to 7,

Wherein the drive shaft (17) in a transition region to the rotor (13) has a freewheel device (33).

[125] 9. Electric motor (25) according to one of the items 1 to 8,

[126] wherein the rotor (13) has a diameter D with 250 mm <D <350 mm.

[127] 10. electric motor (25) according to one of the items 1 to 9, [128] wherein the rotor (13) has a height h of 30 mm <h <60 mm.

Motor vehicle with an electric motor (25) according to one of the numbers 1 to 10, wherein the stator (1) of the electric motor (25) with frame tubes (3) of the motor vehicle is connected and the drive shaft by a drive means with a wheel of the Motor vehicle is connected.

[130] 12. Motor vehicle according to point 11,

[131] wherein the motor vehicle is designed as a bicycle.

[132] 13. Motor vehicle according to item 11 or 12,

[133] wherein the drive means is formed as a chain.

[134] 14. Motor vehicle according to item 11 or 12,

[135] wherein the drive means is designed as a toothed belt.

[136] 15. Motor vehicle according to one of the items 11 to 14,

[137] wherein the electric motor (25) is welded to frame tubes (3) of the motor vehicle.

[138] 16. Motor vehicle according to one of the items 11 to 14,

[139] wherein the electric motor (25) is screwed to frame tubes (3) of the motor vehicle.

[140] 17. A method for operating a motor vehicle with an electric motor (25) designed as an external rotor motor, comprising the following steps:

[141] - providing a stator (1) of the electric motor (25) with windings for

Generation of magnetic fields, wherein the windings (7) have terminals (23) for a supply voltage;

[142] - providing a rotor (13) of the electric motor (25) with permanent magnets, the permanent magnets (16) facing radially opposite the windings (7) with respect to a drive shaft (17);

[143] - Switching the supply voltage such that the magnetic field generated by the current-carrying windings (7) exerts an attractive force on the permanent magnets (16) of the rotor (13) and thus a torque on the rotor (13).

[144] 18. Procedure under 17,

[145] wherein an electronic commutator is used to switch the supply voltage.

[146] 19. Procedure under point 18,

[147] whereby the supply voltage is triggered by a Hall sensor.

[148] 20. Procedure under paragraph 18,

[149] whereby the supply voltage is triggered by evaluating induction currents in the windings (7).

FIG. 9 shows schematically a cross section through the electric motor according to the invention for a motor vehicle according to a first embodiment; FIG. 10 shows schematically a cross section through the electric motor according to the invention for a motor vehicle according to a second embodiment;

[152] FIG. 11 shows schematically a cross section through the electric motor according to the invention for a motor vehicle according to a third embodiment;

[153] FIG. 12 shows schematically a cross section through the electric motor according to the invention for a motor vehicle according to a fourth embodiment;

FIG. 13 shows schematically a cross section through the electric motor according to the invention for a motor vehicle according to a fifth embodiment;

FIG. 14 schematically shows a cross section through the electric motor according to the invention for a motor vehicle according to a sixth embodiment and FIG

FIG. 15 schematically shows a cross section through the electric motor according to the invention for a motor vehicle according to a seventh embodiment.

[157] As far as the electric motor of Figures 1 and 2 is used for the embodiments with gear, in particular, the following description is helpful. Figures 1 and 2 illustrate the principle of the stator and the rotor of the electric motor according to the invention. They show the sake of clarity, not the planetary gear, which is also part of the electric motor according to the invention.

The stator 1 of the external rotor electric motor according to the invention, which is shown schematically in plan view in FIG. 1, has a plate 2, which in this embodiment is an integral part of the frame of a bicycle (not shown in detail) of which in FIG Sections of three frame tubes 3 are shown. The plate 2 has at its outer edge areas 4, which are provided for attachment to the frame tubes 3. Each region 4 is formed in this embodiment as a rectangular flange.

[159] The plate 2 of the stator 1 has on the inside a bearing receptacle 8 with a ball bearing 12. The ball bearing 12 comprises an outer ring 9, an inner ring 11 and arranged between the outer ring 9 and the inner ring 11 balls 10. The inner ring 11 encloses an opening 24 which has a diameter <X. The opening 24 is provided for receiving a drive shaft, not shown in the figure 1. For example, <X can be 20 mm.

[160] The bearing seat 8 of the stator 1 is enclosed by the base ring 5, which carries the yokes 6 of the stator 1. The yokes 6 are each provided with windings 7, which are supplied via here only schematically shown leads 23 with power. The yokes 6 with the windings 7 extend radially from the base ring 5 to the outside and have radially adjoining the windings 7 Jochabschlüsse 34. The yoke ends are also adjoined in the radial direction by a running region 35 for the rotor of the electric motor (not shown in FIG. 1).

[161] Only a few yokes 6 are shown in FIG. For a quiet running behavior of the bicycle and to provide a high torque, however, a much larger number of yokes 6 with windings 7 is provided.

[162] FIG. 2 shows schematically a plan view of the rotor 13 of the electric motor according to the invention. The rotor 13 has a pot shape with a bottom 14 and an edge 15. The rotor 13 has a diameter D of 250 mm <D <350 mm.

[163] On the inner side 26 of the rim 15, a plurality of permanent magnets 16 are arranged. The permanent magnets 16 are arranged such that their polarity changes in the direction of the circumference of the rotor 13, which is indicated by the arrow 36.

[164] The rotor 13 is supported on the drive shaft 17 of the bicycle in this embodiment. The drive shaft 17 has a diameter d _a , which may be 20 mm, for example. The drive shaft 17 has at each of its ends square connections 18 for attachment of a crank 19 for a pedal 20. Of course, instead of the square connection 18, a hexagonal connection or a multiplicity connection or the like can also be used. The pedals are fastened to the cranks 19 by means of a fastening element 21 such as a screw.

[165] Figures 9 to 15 show schematically different embodiments of an electric motor according to the invention.

[166] FIG. 9 schematically shows a cross section through a first embodiment of the electric motor 25 with the rotor 13 and stator 1 described in connection with FIGS. 1 and 2.

[167] The electric motor 25 has a planetary gear 26, which is divided into a sun gear 27, connected via a web 31 planet gears 28 and a ring gear 29. In the view shown in Figure 3, only one planetary gear 28 can be seen, but there may be more than one.

[168] In the embodiment shown in FIG. 9, the web 31 is fixedly connected to the stator 1 of the electric motor 25. Thus, the center 32 of the planetary gear 28 with respect to the stator 1 at rest. The ring gear 33 of the planetary gear 28 is mounted at the center 32, in the ring gear 33 engages the sun gear 27, which is fixedly mounted on the drive shaft 27. The ring gear 29, in which the ring gear 33 of the planetary gear 28 also engages, is fixedly connected to the bottom 14 of the rotor 13.

For mounting the electric motor according to the invention, for example, proceed as follows: The plate 2 of the stator 1 is connected in the designated areas 4 with the frame of a bicycle in which he, for example, as shown in this embodiment, is welded to the frame tubes 3 , Subsequently, the ball bearing 12 is mounted in the bearing receptacle 8 and the yokes 6 with the yoke terminations 34 and the windings 7 become connected to the base ring 5 with the bearing receptacle 8.

[170] Further, the rotor 13 is provided with the permanent magnets 16 attached to the inside of its rim 15 and the ring gear 29 connected to the bottom 14. The rotor 13 is inserted into the cup-shaped in this embodiment, the stator 1 and connected thereto by inserting the drive shaft 17 with the sun gear 27 fixedly connected to the drive shaft 17 in the opening in the inner ring with the ball bearing 12 and the ball bearing 9 of the rotor 13. In this case, the edge 15 comes to rest with the permanent magnets 16 in the running region 35 of the stator 1. Finally, the web 31 is used with the planet gears 28 between the ring gear 29 and sun gear 27 and the web 31 is fixedly connected to the stator 1.

[171] Finally, the cranks are mounted with the pedals on the drive shaft 17.

[172] It is also possible first to assemble the electric motor 25 into the stator 1 by inserting the rotor 13 and only then to connect it to the frame tubes 3. This is particularly possible if the connection of the plate 2 of the stator 1 with the frame tubes 3 by screwing and not by welding.

[173] In operation, the windings 7 are traversed by an electric current and provide a magnetic field which generates a torque by the interaction with the permanent magnets 16 of the rotor 13. For this purpose, the voltage supplying the current through the windings is switched at each moment so that the permanent magnets 16 are attracted to the yoke terminus 34 following in the direction of the circumference of the rotor 13, while they are repelled by the yoke terminus 34 that has just passed.

[174] To switch the supply voltage for the windings 7, an electronic commutator can be used. The triggers of the voltage succeed, for example, contactlessly by a Hall sensor or by evaluating induction currents in the windings.

In this way, the rotor 13 provides a rotational movement, which it transmits through the co-rotating ring gear 29 via the planet gears 28 and the sun gear 27 to the drive shaft 17. A driver of the bicycle can also transmit torque to the drive shaft 17 by means of the pedals.

[176] The torque is then transmitted via the fixed to the drive shaft 17 pinion ring 22 by means of a chain not shown on the wheels of the bicycle. In one embodiment, not shown, a toothed belt pulley is provided instead of the pinion ring and instead of a chain, a toothed belt. It can be provided in this and the other embodiments, a freewheel device with pawls or clamping rollers. This has the advantage that it is due to the Freewheeling for the driver is not necessary to constantly operate the pedals, but the rotation of the drive shaft 17 can also be disconnected from the movement of the pedals, so that a drive of the bicycle takes place solely on the electric motor 25 without the assistance of the driver.

[177] In this embodiment, it may be advantageous to choose the rotational speed of the ring gear 29 and thus of the rotor 13 greater than that of the drive shaft 17. At a normal cadence of the driver, it is thus possible to operate the electric motor 25 at a higher frequency as the cadence. In some applications, however, it may also be advantageous in this and the other embodiments, conversely, to achieve a gear ratio through the planetary gear, so that the electric motor can be operated at a frequency lower than the cadence. In this case, the desired ratio of the frequencies can be very flexibly adjusted by a suitable choice of the diameter of the sun gear 27, planetary gear 28 and ring gear 29.

[178] In addition, it is advantageous that the planetary gear 26 is particularly simple in this embodiment and thus lightweight and robust and has a high efficiency.

FIG. 10 shows a second embodiment of the electric motor 25 according to the invention. This embodiment differs from the first embodiment in the arrangement of the elements forming the planetary gear 26. In this embodiment, the sun gear 27 is fixedly connected by welds 11 with a hollow shaft 10, which in turn is welded to the bottom 2 of the stator 1. Firmly connected to the hollow shaft 10 is also the base ring 5 for the yokes 6. Thus, in this embodiment, the sun gear 27 in the system of the stator 1 at rest.

The rotor 13 is mounted by means of the ball bearing 9 on the hollow shaft and otherwise constructed as in the first embodiment. The bottom 14 of the rotor 13 is fixedly connected to the ring gear 29.

In the ring gear 29 and the sun gear 27, the planet gear 28 engages, which is rotatably mounted with its center 32 on the web 31. The web 31 is fixedly connected to the drive shaft 17. Thus, the web 31 transmits its rotary motion directly to the drive shaft 17, on which in turn cranks 19 are mounted for pedals. In operation of this embodiment of the bicycle, the ring gear 29 integral with the rotor 13 rotates at the same frequency as the rotor 13 rotates. The planetary gear 28, which rolls between ring gear 29 and stationary sun gear 27, transmits the torque to the web 31, at which the torque is tapped via the fixed connection with the drive shaft 17. On the drive shaft 17, a sprocket ring 22 is mounted, which transmits the torque further to the wheels of the bicycle by means of a drive means, not shown. In this embodiment, it is particularly advantageous that the rotational speed of the ring gear 29 and thus of the rotor 13 is greater than that of the web 31 and thus the drive shaft 17. At a normal cadence of the driver, it is thus possible in this embodiment, the Electric motor 25 to operate at a higher frequency than the cadence. In this case, the desired ratio of the frequencies can be very flexibly adjusted by a suitable choice of the diameter of the sun gear 27, planetary gear 28 and ring gear 29. In addition, it is advantageous that because of the omission of the ball bearing 12 more space for the stator is present, so that the yokes 6 can be made longer and provided with more windings 27.

FIG. 11 shows a third embodiment of the electric motor 25 according to the invention. This embodiment differs from the first and the second embodiment in the arrangement of the elements forming the planetary gear 26. In this embodiment, as in the first embodiment, the ring gear 29 is fixedly connected to the stator 1 and thus in the system of the stator 1 at rest.

[184] The sun gear 27 is fixedly connected to a hollow shaft 10 or integral with this. The hollow shaft 10 in turn is fixedly connected to the bottom 14 of the rotor 13. The sun gear 27 thus rotates at the frequency of the rotor thirteenth

[185] In the hollow shaft 10, the drive shaft 17 is rotatably mounted, which is connected via the sprocket ring 22 with the web 31. The web 31 is mounted on the hollow shaft 10 by means of a ball bearing 24. In this embodiment, therefore, the torque is tapped off the web 31 as in the second embodiment.

[186] In this embodiment, it is advantageous that the rotational speed of the

Sun gear 27 and thus of the rotor 13 is greater than that of the web 31 and thus the drive shaft 17. At a normal cadence of the driver, it is thus possible in this embodiment, the electric motor 25 to operate at a higher frequency than the cadence. In this case, the desired ratio of the frequencies can be very flexibly adjusted by a suitable choice of the diameter of the sun gear 27, planetary gear 28 and ring gear 29.

FIG. 12 shows a fourth embodiment of the electric motor 25 according to the invention. This embodiment differs from the embodiments already described by the arrangement of the elements forming the planetary gear 26. In this embodiment, a planetary gear 26 is arranged symmetrically on both sides of the electric motor 25. For this purpose, the stator 1 has a lid 36 opposite the bottom 2.

In this embodiment, each of the web 31 is fixedly connected to the bottom 2 and the cover 36 of the stator 1 and thus in the system of the stator 1 at rest. The sun gear 27 is fixedly connected to the bottom 14 of the rotor 13 and thus rotates at the same frequency as the rotor 13. The drive shaft 17 is not carried out continuously in this embodiment, but interrupted on each side for the planetary gear 26. The sun gear 27 engages on each side in the ring gear 33 of the planetary gear 28 that rolls in the ring gear 29. The ring gear 29 is fixedly connected to a sprocket ring 22, respectively.

[189] In this embodiment, it is advantageous that the rotational speed of the

[190] In addition, the electric motor 25 and in particular the planetary gear 26 in this embodiment, although relatively expensive, but also designed symmetrically and thus well balanced.

[191] FIG. 13 shows a fifth embodiment of the electric motor 25 according to the invention. This embodiment differs from the embodiments already described by the arrangement of the elements forming the planetary gear 26. In this embodiment, the ring gear 29 is fixedly connected to the stator 1 and thus in the system of the stator 1 at rest.

The sun gear 27 is fixedly connected to the drive shaft 17 or integrally formed therewith. The drive shaft 17 is fixedly connected to the bottom 14 of the rotor 13 and thus rotates at the same frequency as the rotor 13th

[193] At the web 31 and at the center 32 of the planetary gear 28, a sprocket ring 22 is mounted, via which the torque is transmitted to the wheels of the bicycle by means of a drive means, not shown.

[194] In this embodiment, it is advantageous that the planetary gear is particularly simple and therefore lightweight and robust. The rotor 13 is fixedly connected to the drive shaft 17, on which also the cranks, not shown here are mounted with pedals for the driver. Thus, the cadence of the driver in this embodiment corresponds to the frequency of the rotor 13.

By the connection of the pinion gear ring 22 with the center 32 of the planetary gear 28 and thus with the web 31 takes place between the sun gear 27 and sprocket ring 22, a reduction, which is adjusted by a suitable choice of the diameter of the sun gear 27, planet gear 28 and ring gear 29 can be.

[196] FIG. 14 shows a sixth embodiment of the electric motor 25 according to the invention. This embodiment differs from the embodiments already described by the arrangement of the planetary gear 26 forming Elements. In this embodiment, the sun gear 27 is fixedly connected to a hollow shaft 10 or designed in one piece with this. The hollow shaft 10 itself is firmly connected to the bottom 2 of the stator 1. The sun gear 27 is thus in the system of the stator 1 at rest.

[197] The rotor 13 is mounted on the hollow shaft 10 by means of the ball bearing 9. The bottom 14 of the rotor 13 is fixedly connected to the web 31.

[198] In the ring gear 29 and the sun gear 27, the planet gear 28 engages, which is rotatably mounted with its center 32 on the web 31. The ring gear 29 is fixedly connected to the drive shaft 17. Thus, the rotor 13 transmits its rotational movement via the web 31 to the planetary gear 28, which in turn engages the fixed sun gear 27 and the ring gear 29 and thus acts on the drive shaft 17 via the ring gear 29.

[199] The sprocket rim, not shown in this figure, may for example be mounted externally on the ring gear 29 or mounted directly on the drive shaft 17.

[200] In this embodiment, either the frequency of the rotor 13 corresponds to that of the ring gear 29 and thus the cadence of the driver, or if the pinion gear is mounted on the planetary gear 28, the frequency of the rotor is less than the cadence of the driver. In the latter case, the electric motor is only suitable for more specialized applications.

[201] It is advantageous in the sixth embodiment that as in the second

Embodiment plenty of space for the rotor 13 is present and thus the yokes 6 can be made particularly large with the windings 7.

FIG. 15 schematically shows a cross section through the electric motor according to the invention for a motor vehicle according to a sixth embodiment, which essentially corresponds to the third embodiment according to FIG. The difference is that the drive shaft 17 is slightly shortened and is not intended to receive cranks with pedals. In this embodiment, the electric motor is particularly suitable for driving a motorcycle. Of course, other embodiments such as those shown in Figures 12 to 14 are suitable for use on a motorcycle that has no cranks with pedals.

[203] In the geared embodiments described above, the following reference numerals have been used:

[204] 1 stator

[205] 2 plate

[206] 3 frame tube

[207] 4 areas

[208] 5 base ring

[209] 6 yoke [210] 7 windings

[211] 8 bearing intake

[212] 9 ball bearings

[213] 10 hollow shaft

[214] 11 weld

[215] 12 ball bearings

[216] 13 rotor

[217] 14 soil

[218] 15 edge

[219] 16 permanent magnet

[220] 17 Drive shaft

[221] 18 square connection

[222] 19 crank

[223] 20 pedals

[224] 21 fastener

[225] 22 sprocket wheel

[226] 23 supply line

[227] 24 ball bearings

[228] 25 electric motor

[229] 26 planetary gears

[230] 27 sun wheel

[231] 28 planetary gear

[232] 29 ring gear

[233] 31 footbridge

[234] 32 Center

[235] 33 sprocket

[236] 34 yoke conclusion

[237] 35 Running range

[238] 36 lids

[239] The embodiments with gear can also be with the following

Characteristics of points 1 to 38, and expressly attaching importance to the combinations of features resulting from

[240] An electric motor (25) for a motor vehicle, comprising:

[241] - a stator (1) having predetermined areas (4) for connection to a vehicle frame;

[242] - a rotor (13);

[243] - predetermined areas for receiving a drive means; [244] - a planetary gear (26);

[245] - the electric motor (25) is designed as an external rotor motor.

[246] 2. electric motor according to item 1,

[247] wherein the rotor (13) is arranged on a drive shaft (17) which is rotatably mounted in the stator (1).

[248] 3. electric motor according to paragraph 2,

[249] wherein the drive shaft (17) is mounted in a hollow shaft (10). [250] 4. electric motor (25) according to item 2 or 3,

[251] wherein at the ends of the drive shaft (17) cranks (19) with pedals (20) can be fastened.

[252] 5. Electric motor (25) according to one of the numbers 1 to 4, wherein the drive shaft (17) in a transition region to the rotor (13) a

Freewheel device (33).

[254] 6. Electric motor according to one of the numbers 1 to 5,

[255] wherein a web (31) of the planetary gear (26) is fixedly connected to the stator (1). [256] 7. Electric motor according to item 6, [257] wherein a ring gear (29) of the planetary gear (26) is fixedly connected to the rotor (13).

[258] 8. Electric motor according to item 6, [259] wherein a sun gear (27) of the planetary gear (26) is fixedly connected to the rotor (13).

[260] 9. Electric motor according to one of the numbers 1 to 5, [261] wherein a sun gear (27) of the planetary gear (26) is fixedly connected to the stator (1).

[262] 10. Electric motor according to item 9, [263] wherein a ring gear (29) of the planetary gear (26) is fixedly connected to the rotor (13).

[264] 11. Electric motor according to point 9,

[265] wherein a web (31) of the planetary gear (26) is fixedly connected to the rotor (13). [266] 12. Electric motor according to one of the numbers 1 to 5, [267] wherein a ring gear (29) of the planetary gear (26) is fixedly connected to the stator (1).

[268] 13. Electric motor according to item 12, [269] wherein a sun gear (27) of the planetary gear (26) is fixedly connected to the rotor (13).

[270] 14. Electric motor according to point 12,

[271] wherein a web (31) of the planetary gear (26) is fixedly connected to the rotor (13). [272] 15. Electric motor (25) according to one of the items 1 to 14, [273] wherein the electric motor (25) is designed as an electronically commutated DC external rotor motor.

[274] 16. Electric motor (25) according to one of the items 1 to 15,

[275] wherein the electric motor (25) is brushless and the rotor (13) has a number of permanent magnets (16).

[276] 17. Electric motor (25) according to one of the numbers 1 to 16,

[277] wherein the areas for receiving a drive means as a sprocket ring (22) are formed.

[278] 18. Electric motor (25) according to one of the items 1 to 16,

[279] wherein the areas for receiving a drive means are designed as a toothed belt pulley.

[280] 19. Electric motor (25) according to one of the items 1 to 16,

[281] wherein the areas for receiving a drive means are designed as a cardan pinion.

[282] 20. Electric motor (25) according to one of the items 17 to 19,

[283] wherein the areas for receiving the drive means are fixedly connected to the drive shaft (17) or to areas of the planetary gear (26).

[284] 21. Electric motor (25) according to one of the numbers 1 to 20,

[285] wherein the rotor (13) has a diameter D with 250 mm <D <350 mm.

[286] 22. Electric motor (25) according to one of the items 1 to 21,

[287] wherein the rotor (13) has a height of 30 mm <h <60 mm.

[288] 23. Motor vehicle with an electric motor (25) according to one of the numbers 1 to 22, wherein the stator (1) of the electric motor (25) with frame tubes (3) of the motor vehicle and a sprocket rim (22) of the electric motor (25) a drive means is connected to a wheel of the motor vehicle.

[289] 24. Motor vehicle as defined in paragraph 23,

[290] wherein the motor vehicle is designed as a bicycle.

[291] 25. Motor vehicle as defined in paragraph 23,

[292] wherein the motor vehicle is designed as a motorcycle.

[293] 26. Motor vehicle according to one of the items 23 to 25,

[294] wherein the drive means is designed as a chain.

[295] 27. Motor vehicle according to one of the items 23 to 25,

[296] wherein the drive means is designed as a toothed belt.

[297] 28. Motor vehicle according to one of the items 23 to 27,

[298] the pinion gear (22) being fixedly connected to a drive shaft (17).

[299] 29. Motor vehicle according to one of the items 23 to 28,

[300] wherein the pinion gear (22) is fixedly connected to a web (31) of the planetary gear (26). [301] 30. Motor vehicle according to one of the items 23 to 28,

[302] wherein the pinion gear (22) is fixedly connected to a ring gear (29) of the planetary gear (26).

[303] 31. A motor vehicle according to any one of items 23 to 28, wherein the pinion ring (22) is fixedly connected to a sun gear (27) of the planetary gear (26).

[305] 32. Motor vehicle according to one of the numbers 23 to 31, [306] wherein the electric motor (25) is welded to frame tubes (3) of the motor vehicle.

[307] 33. Motor vehicle according to one of the numbers 23 to 32, [308] wherein the electric motor (25) is screwed to frame tubes (3) of the motor vehicle.

[309] 34. Motor vehicle according to one of the numbers 23 to 33, wherein the motor vehicle has a wheel suspension with a rocker, which is mounted rotatably about a rotation axis on the motor vehicle, wherein the axis of rotation of the rocker is substantially the axis of rotation of the rotor (13 ) corresponds. [311] 35. A method for operating a motor vehicle with an electric motor (25) designed as an external rotor motor with a planetary gear (26), the following

Comprising: [312] providing a stator (1) of the electric motor (25) with windings for

Generation of magnetic fields, wherein the windings (7) terminals (23) for a

Have supply voltage; [313] - providing a rotor (13) of the electric motor (25) with permanent magnets, wherein the permanent magnets (16) opposite to the windings (7) with respect to a rotational axis of the rotor (13) in the radial direction; [314] - Switching the supply voltage such that the current flowing through

Windings (7) generated magnetic field, an attraction force on the permanent magnets (16) of the rotor (13) and thus a torque on the rotor (13) exerts. [315] 36. The method of item 35, [316] wherein an electronic commutator is used to switch the supply voltage.

[317] 37. The procedure under paragraph 36,

[318] whereby the supply voltage is triggered by a Hall sensor. [319] 38. The method according to item 36, [320] wherein the supply voltage is determined by evaluating induction currents in the

Windings (7) is triggered.

Claims

[1] 1. Electric motor (25) for a motor vehicle, which has the following:

- a stator (1) with predetermined areas (4) for connection to a vehicle frame;

- a rotor (13);

- predetermined areas for receiving a drive means;

- a planetary gear (26);

- The electric motor (25) is designed as an external rotor motor, wherein the rotor (13) is rotatably mounted with respect to the stator (1), the drive shaft (17) being mounted in a hollow shaft (10), with a ring gear (29) of the Planetary gear (26) is connected to the rotor (13), a sun gear (27) of the planetary gear (26) being connected to the hollow shaft (10), and a web (31) of the planetary gear (26) to the anti-reb shaft (17 ) connected is.

[2] Electric motor (25) according to claim 1, wherein cranks (19) with pedals (20) can be attached to the ends of the drive shaft (17).

[3] Electric motor (25) according to one of claims 1 to 2, wherein the drive shaft (17) has a freewheel device (33) in a transition region to the rotor (13).

[4] Electric motor (25) according to one of claims 1 to 3, wherein the electric motor (25) is designed as an electronically commutated direct current external rotor motor.

[5] Electric motor (25) according to one of claims 1 to 4, wherein the electric motor (25) is designed to be brushless and the rotor (13) has a number of permanent magnets (16).

[6] Electric motor (25) according to one of claims 1 to 5, wherein the areas for receiving a drive means are designed as a pinion ring (22).

[7] Electric motor (25) according to one of claims 1 to 6, wherein the areas for receiving a drive means are designed as a toothed belt pulley.

[8] Electric motor (25) according to one of claims 1 to 7, wherein the areas for receiving a drive means are designed as cardan pinions.

[9] Electric motor (25) according to one of claims 1 to 8, wherein the areas for receiving the drive means are firmly connected to the drive shaft (17) or to areas of the planetary gear (26).

[10] Motor vehicle with an electric motor (25) according to one of claims 1 to 9, wherein the stator (1) of the electric motor (25) with frame tubes (3) of the motor vehicle and a pinion ring (22) of the electric motor (25) by a drive means connected to a wheel of the motor vehicle.

[11] Motor vehicle according to claim 11, wherein the rotor (13) has a diameter D with 250 mm <D <350 mm and wherein the rotor (13) has a height with 30 mm <h <60 mm.

[12] Motor vehicle according to one of claims 10 or 11, wherein the drive means is designed as a chain.

[13] Motor vehicle according to one of claims 10 to 12, wherein the drive means is designed as a toothed belt.

[14] Motor vehicle according to one of claims 10 to 13, wherein the electric motor (25) is screwed or welded to frame tubes (3) of the motor vehicle.

[15] Motor vehicle according to one of claims 10 to 14, wherein the motor vehicle has a wheel suspension with a rocker arm which is rotatably mounted on the motor vehicle about an axis of rotation, the axis of rotation of the rocker arm essentially corresponding to the axis of rotation of the rotor (13).