Drive unit for a vehicle that can be propelled at least partially by muscle power and vehicle with such a drive unit

Abstract

The invention relates to a drive unit for a vehicle (1) that can be propelled at least partially by muscle power, comprising a hub housing (2) configured to be rotationally fixed to a drive wheel (3) of the vehicle (1), a transmission (4) arranged therein, and an electric machine (5) with a rotor (6) and a stator (7), wherein the transmission (4) is arranged coaxially to the electric machine (5) and radially within the electric machine (5), wherein the rotor (6) is rotationally fixed to the hub housing (2) and the stator (7) is rotationally fixed to a transmission element, or the stator (7) is rotationally fixed to the hub housing (2) and the rotor (6) is rotationally fixed to a transmission element. The invention further relates to a vehicle (1) that can be propelled at least partially by muscle power, comprising at least two wheels and such a drive unit.

Description

[0001] The invention relates to a drive unit for a vehicle that can be propelled at least partially by muscle power. Furthermore, the invention relates to a vehicle with such a drive unit. In particular, the vehicle is designed as a bicycle or e-bike and has at least two wheels.

[0002] For example, DE 27 12 456 A1 discloses a drive system with an electric motor equipped with a rotatably mounted rotor and a stator. The stator of the electric motor is rotatably mounted relative to the rotor and coupled to a flywheel for storing rotational energy.

[0003] Further electric drive systems for bicycles are known from publications US 2 514 460 A, WO 2020 / 025 613 A1, EP 0 984 884 B1, FR 2 264 676 A1 and DE 93 16 748 U1.

[0004] The object of the invention is to create an alternative drive unit for a vehicle that can be propelled at least partially by muscle power. In particular, the drive unit should have a compact design in the axial direction. This object is achieved by the subject matter of the independent claims. Preferred embodiments can be found in the dependent claims, the description, and the figures.

[0005] A drive unit according to the invention for a vehicle that can be propelled at least partially by muscle power comprises a hub housing configured to be rotationally fixed to a rim of a drive wheel of the vehicle, a gearbox arranged therein, and an electric machine arranged coaxially thereto with a rotor and a stator, wherein the gearbox is arranged radially within the electric machine, the rotor being rotationally fixed to the hub housing, and the stator being rotationally fixed to a gearbox element. Alternatively, the stator is rotationally fixed to the hub housing, and the rotor is rotationally fixed to a gearbox element. Thus, the rotor and the stator can rotate about the wheel axis. Because the stator does not need to be supported by a stationary component, particularly in the area of ​​the wheel axis, the drive unit can be designed more compactly.Therefore, a component connecting the stator to the radially inner wheel axle can be omitted. This saves components and thus also material and weight.

[0006] If the rotor is non-rotatably connected to the hub housing and the stator is non-rotatably connected to a gear element, the stator is preferably arranged radially inside the rotor, with the gear element also arranged radially inside the stator. Regardless of whether the rotor or the stator is non-rotatably connected to the hub housing, the rotor, stator, and gear element are arranged radially nested and axially overlapping, resulting in a particularly compact design in the axial direction for the drive unit, which is configured as a wheel hub motor for a vehicle, especially a bicycle.

[0007] The transmission element comprises at least one ring gear. For example, the transmission element is designed as a ring gear. For example, the transmission element is designed as a ring gear with multiple internal tooth sections and different inner diameters, wherein all internal tooth sections are rotationally fixed to the stator or the rotor. The ring gear can be formed as a single piece or from several rotationally fixed sections.

[0008] Furthermore, the transmission element includes a planet carrier. For example, the transmission element is designed as a planet carrier. Several axially adjacent planet gears with different outer diameters are rotatably mounted on the planet carrier, with each planet gear meshing with a ring gear and a sun gear of the transmission. The planet carrier is non-rotatably connected to the stator or the rotor.

[0009] According to one embodiment, sliding contacts are used for electrical energy transfer between a circuit board and the rotor and / or the stator. The sliding contacts transfer the electrical energy by contacting the circuit board and rotor and / or the circuit board and stator. This can reduce manufacturing costs.

[0010] According to an alternative embodiment, electrical energy transfer between the circuit board and the rotor and / or stator is inductive. Induction allows for contactless transfer of electrical energy between the circuit board and rotor and / or between the circuit board and stator. This reduces wear.

[0011] According to one embodiment, the transmission is designed as a manual transmission, a continuously variable transmission (CVT), or a rigid transmission. Alternatively or additionally, the transmission includes a planetary gear set. A manual transmission comprises a shifting mechanism or at least a shifting element for changing gear ratios, thereby enabling multiple fixed gear ratios. A continuously variable transmission (CVT) allows for stepless adjustment of the gear ratio, resulting in smooth and jerk-free acceleration, which particularly improves driver comfort. A rigid transmission has a fixed gear ratio, is not shiftable, and can be manufactured cost-effectively. A planetary gear set comprises at least one sun gear, a ring gear, and a planet carrier with several planet gears that mesh with the ring gear and the sun gear.Alternatively, the transmission can also be designed as a wave gear or eccentric gear, in particular a cycloidal gear. Regardless of the transmission design, the electric motor and the transmission form a wheel hub drive for a drive wheel.

[0012] According to one embodiment, the transmission's switching mechanism is fixed in a stationary position. For example, the switching mechanism comprises several switching elements. Preferably, the switching mechanism is configured to fix a transmission element, preferably a sun gear, in a stationary position and thus lock it against rotation. For example, the transmission's switching mechanism is arranged on a rotationally fixed axis. This not only simplifies the design and assembly but also saves installation space and components.

[0013] The invention also relates to a vehicle that can be propelled at least partially by muscle power, comprising at least two wheels and a drive unit according to the invention. In particular, the vehicle is designed as a bicycle or e-bike. For example, the vehicle can have three or more wheels, wherein either one or more wheels can be electrically driven.

[0014] According to one embodiment, the vehicle comprises a generator with a rotor and a stator, wherein the generator's rotor is non-rotatably connected to the vehicle's pedal crankshaft. Thus, the generator is designed as a pedal generator and converts the kinetic energy introduced by the rider via the pedals into electrical energy. The harder the rider pedals and the greater the generator's resistance, the greater the electrical power generated by the generator. The electric machine, designed as a wheel hub motor, generates drive power at the drive wheel according to the generator's electrical output. For example, the generator and the wheel hub motor are connected to each other, at least indirectly or directly. In particular, the vehicle can have several wheel hub motors, each driving a wheel.If a pedal generator is arranged on the crankshaft, a mechanical connection between the crankshaft and the drive wheel is unnecessary. If a mechanical connection, for example a traction drive, particularly a chain or belt drive, is arranged between the crankshaft and the drive wheel, a pedal generator on the crankshaft can be omitted. According to one embodiment, the vehicle includes an electrical energy storage device that is electrically connected to the generator and the wheel hub motor. The energy storage device serves, on the one hand, to store electrical energy, in particular to absorb the electrical energy from the generator, and on the other hand, to provide electrical energy, in particular to feed electrical energy into the wheel hub motor and drive the drive wheel.

[0015] Further measures improving the invention are described in more detail below, together with a description of preferred embodiments of the invention, with reference to the figures. Fig. 1 a highly simplified schematic representation of a vehicle according to the invention in a first embodiment, Fig. 2 a highly simplified schematic representation of a vehicle according to the invention in a second embodiment, Fig. 3 a highly simplified schematic representation of a drive unit according to the invention in a first embodiment and Fig. 4 a highly simplified schematic representation of a drive unit according to the invention in a second embodiment.

[0016] In Fig. Figure 1 shows a vehicle 1 according to the invention, which can be propelled at least partially by muscle power, comprising a rear wheel designed as a drive wheel 3, a front wheel 42 which is pivotably arranged on a frame 43 via a fork, and a drive unit according to the invention. The vehicle 1 is designed in this case as a bicycle, in particular as an e-bike.

[0017] A crank shaft 41 is connected to pedals 45 via crank arms 44, with a generator 40, designed as a pedal generator, being effectively connected to the crank shaft 41. The drive unit comprises an electric machine 5, designed as a wheel hub motor, and a gearbox 4, which are jointly arranged in a hub housing 2 and effectively connected to the drive wheel 3 of the bicycle in order to generate drive power at the drive wheel 3 according to an electrical output of the generator 40. An electrical energy storage device 46 is arranged on the frame 43 of the bicycle and is electrically connected to the generator 40 and the electric machine 5.

[0018] When the rider pedals, the generator 40 produces electrical power, which serves as a measure of the electrical energy from the energy storage device 46 fed into the electric machine 5 at the drive wheel 3. Specifically, the electrical drive power provided by the electric machine 5 at the drive wheel 3 is the product of the electrical power of the generator 40 and a factor selectable by the rider by choosing the driving mode. There is no mechanical connection, in particular no chain or belt drive, between the wheel hub, which rotatably mounts the drive wheel 5 on the frame 43, and the pedal crank shaft 41, so the drive wheel 3 can only be driven by the drive unit.

[0019] Fig. Figure 2 shows an alternative embodiment of a vehicle 1 according to the invention, comprising a rear wheel designed as a drive wheel 3, a front wheel 42, and a drive unit according to the invention. The vehicle 1 is as in the embodiment according to Fig. 1, to which reference is made, is also designed as a bicycle, in particular as an e-bike. The only difference between these two embodiments is that the generator on the pedal crank shaft 41 is omitted and the pedal crank shaft 41 has a mechanical connection via a traction drive 50 to the drive unit and thus also to the drive wheel 3. Therefore, the rider can propel the bicycle with muscle power when the energy storage 46 is depleted. This reduces manufacturing costs.

[0020] Fig. Figure 3 shows a highly simplified section of a first embodiment of the drive unit according to the invention, in particular the upper half as seen from the axis of rotation 49. A hub housing 2 of the drive unit is non-rotatably connected to a rim of the drive wheel 3 via spokes 47. A gearbox 4 and an electric machine 5 with a rotor 6 and a stator 7 are arranged in the hub housing 2. The gearbox 4 is arranged coaxially with the electric machine 5 and radially within the electric machine 5, with the rotor 6 being non-rotatably connected to the hub housing 2 and the stator 7 being non-rotatably connected to a gearbox element. Thus, the rotor 6 and the stator 7 can rotate about the wheel axis 48, which is non-rotatably connected to the frame 43. Sliding contacts 8 are provided for electrical energy transmission between a circuit board 9 and the rotor 6 and between the circuit board 9 and the stator 7.Alternatively, the electrical energy transfer between the circuit board 9 and the rotor 6 and / or the stator 7 can be inductive. Because the stator 7 is not supported by a stationary component, in particular by the wheel axle 48, the drive unit can be designed more compactly.

[0021] The transmission element comprises three ring gears 11, 21, 31, which are rotationally fixed to each other and to the stator 7. The ring gears 11, 21, 31 are part of the transmission 4, which is designed as a shift transmission and includes three planetary gear sets and a shifting mechanism 20. The first planetary gear set includes, in addition to the ring gear 11, a sun gear 12 and planet gears 13, which are rotatably mounted on a planet carrier 10 and mesh with the ring gear 11 and the sun gear 12. The second planetary gear set includes, in addition to the ring gear 21, a sun gear 22 and planet gears 23, which are rotatably mounted on the planet carrier 10 and mesh with the ring gear 21 and the sun gear 22. The third planetary gear set includes, in addition to the ring gear 31, a sun gear 32 and planet gears 33, which are rotatably mounted on the planet carrier 10 and mesh with the ring gear 31 and the sun gear 32.The planet carrier 10 is thus designed as a common planet carrier 10 for all planet gears 13, 23, 33 and is connected to the hub housing 2 in a rotationally fixed manner.

[0022] The shifting mechanism 20 of the gearbox 4 is arranged in the wheel axle 48 and fixed above it to the frame 43 of the bicycle. The shifting mechanism 20 has three shifting elements, each of which interacts with one of the sun gears 12, 22, 32 to change the gear ratio of the gearbox 4 by blocking the respective sun gear 12, 22, 32. The rotor 6, the stator 7, and the gearbox 4 are arranged radially nested and axially overlapping, resulting in a particularly compact design for the drive unit, which is designed as a wheel hub drive, in the axial direction.

[0023] Fig. Figure 4 shows a second embodiment of the drive unit according to the invention. This drive unit is similar to the drive unit according to [reference to figure]. Fig. 3, to which reference is made, is designed as a particularly compact wheel hub drive. The difference between these two embodiments is that, firstly, the stator 7 and the rotor 6 are interchanged, and secondly, the connection of the planetary gear sets is reversed. In the present embodiment, the ring gears 11, 21, 31 are non-rotatably connected to the hub housing 2, with the planet carrier 10 also non-rotatably connected to the rotor 6. The stator 7 is non-rotatably connected to the hub housing 2, with the rotor 6 arranged inside the stator 7. Otherwise, the embodiment corresponds to the embodiment shown in the figure below. Fig. 4 according to the exemplary embodiment Fig. 3. According to a further alternative embodiment, both in the embodiment shown in Fig. 3 as well as in the embodiment according to Fig. 4 the position and thus also the connection of rotor 6 and stator 7 can be swapped without changing the connection of the planetary gear sets. Reference symbol list 1 vehicle 2 hub shells 3 drive wheel 4 gearboxes 5 electric machine 6 Rotor 7 Stator 8 sliding contact 9 circuit boards 10 planetary carriers 11 Ring gear 12 sun wheel 13 planetary gear 20 shift mechanism 21 Ring gear 22 sun wheel 23 planetary gear 31 Ring gear 32 sun wheel 33 planetary gear 40 Generator 41 Crankshaft 42 front wheel 43 frames 44 Crankset 45 pedals 46 Energy storage 47 spokes 48 wheel axle 49 Rotation axis 50 traction drive

Claims

Drive unit for a vehicle (1) that can be propelled at least partially by muscle power, comprising a hub housing (2) configured to be rotationally fixed to a drive wheel (3) of the vehicle (1), a transmission (4) arranged therein, and an electric machine (5) with a rotor (6) and a stator (7), wherein the transmission (4) is arranged coaxially to the electric machine (5) and radially within the electric machine (5), wherein either the rotor (6) is rotationally fixed to the hub housing (2) and the stator (7) is rotationally fixed to a transmission element, or the stator (7) is rotationally fixed to the hub housing (2) and the rotor (6) is rotationally fixed to a transmission element, characterized in that the transmission element comprises a ring gear (11). Drive unit for a vehicle (1) that can be propelled at least partially by muscle power, comprising a hub housing (2) configured to be rotationally fixed to a drive wheel (3) of the vehicle (1), a gearbox (4) arranged therein, and an electric machine (5) with a rotor (6) and a stator (7), wherein the gearbox (4) is arranged coaxially to the electric machine (5) and radially within the electric machine (5), wherein either the rotor (6) is rotationally fixed to the hub housing (2) and the stator (7) is rotationally fixed to a gearbox element, or wherein the stator (7) is rotationally fixed to the hub housing (2) and the rotor (6) is rotationally fixed to a gearbox element, characterized in that the gearbox element comprises a planet carrier (10). Drive unit according to one of the preceding claims, characterized in that sliding contacts (8) are formed for electrical energy transmission between a circuit board (9) and the rotor (6) and / or the stator (7). Drive unit according to any one of claims 1 to 3, characterized in that the electrical energy transfer between a circuit board (9) and the rotor (6) and / or the stator (7) is inductive. Drive unit according to one of the preceding claims, characterized in that the transmission (4) is designed as a manual transmission, continuously variable transmission or as a rigid transmission and / or comprises a planetary gear set. Drive unit according to one of the preceding claims, characterized in that a switching mechanism (20) of the transmission (4) is fixed in a stationary position. Vehicle (1) that can be propelled at least partially by muscle power, comprising at least two wheels and a drive unit according to one of the preceding claims. Vehicle (1) according to claim 7, characterized by a generator (40) with a rotor and a stator, wherein the rotor of the generator (40) is connected to a pedal crank shaft (41) of the vehicle (1) in a rotationally fixed manner.

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