DE102021116701B3 - Driving device for an electric bicycle and electric bicycle - Google Patents

Abstract

A drive device (5) for an electric bicycle (1) has a motor unit with an electric motor for driving the electric bicycle (1). The drive device (5) also includes a pedal crankshaft (6) which is rotatable about an axis of rotation (R) and extends through a motor housing (7) of the motor unit. The drive device (5) also has a chainring system (11) which is coupled to the pedal crankshaft (6) in order to drive the electric bicycle (1). In addition, the drive device (5) includes a torque sensor unit (10), which is arranged with respect to the axis of rotation (R) outside of the motor housing (7) between the chain ring system (11) and the motor housing (7) and for measuring a torque of the chain ring system (11) comprises a pickup unit (14) with pickup electronics (16) and a radial measuring area (20). The pickup unit (14) and the measuring section are aligned so that a measuring direction is formed between them along the axis of rotation (R).

Description

The invention relates to a drive device for an electric bicycle and an electric bicycle with such a drive device.

Bicycles are a cost-effective, easy-to-handle and emission-free means of transportation. They have also been used as sports or fitness equipment, and types that are particularly suitable for different sports applications have emerged.

In recent years, enthusiasm for electric bicycles (especially so-called "pedelecs") has been growing, despite the high weight and price of bicycles. Potential customers are not only older, less fit cyclists or cyclists who are free from sporting ambitions, but also sporty, younger cyclists, whether for use on the way to work or because of the possibility of using them to extend the radius of action without overstraining one's own physique and/or the increase cruising speed. Interest in electrically assisted mountain bikes seems to be growing, especially among mountain bikers. In the case of electric bicycles, it is important to provide a reliably supporting drive system that enables high power transmission.

It is the object on which the invention is based to create a drive concept for electric bicycles that has a clear and space-saving design and enables reliable support.

The object is achieved by a drive device having the features of claim 1 and by an electric bicycle having the features of claim 12.

According to one aspect, a drive device for an electric bicycle is disclosed. The drive device has a motor unit with an electric motor for driving the electric bicycle, which is arranged in a motor housing. The drive device further has a pedal crankshaft which is rotatable about an axis of rotation and which extends through the motor housing. The drive device further includes a chainring system, which is coupled to the pedal crankshaft for driving the electric bicycle, and a torque sensor unit, which is designed to measure a torque of the chainring system. The torque sensor unit is arranged with respect to the axis of rotation outside of the motor housing between the chainring system and the motor housing and comprises a radial measuring area and a pickup unit with pickup electronics for measuring a torque of the chainring system. The pickup unit and the radial measuring portion are aligned so that a measuring direction is formed between them along the axis of rotation.

A reliable drive concept for electric bicycles can be implemented by means of the drive device described, which enables a space-saving design. In particular, due to the external arrangement of the torque sensor unit and the set up radial torque measurement, a compact axial design of the drive device can be implemented, which helps to keep the space required in the motor housing small and to be able to make the motor housing correspondingly slim. The drive device described is particularly suitable as an electric bicycle drive system for mounting on a down tube or on a seat tube of the electric bicycle.

The radial measuring range extends around the axis of rotation and can completely encircle it or can also be configured only in sections on a segment of a circle. The measurement direction between the pickup unit and the measurement area is oriented essentially parallel to the axis of rotation. However, this can also include a relatively slight inclination of the measurement direction with regard to the rotation object, so that the measurement direction is in each case predominantly formed along the rotation axis and not set up perpendicular to it.

The radial measuring range forms the section to be measured in order to determine a torque that acts on a chainring of the chainring system, for example. It corresponds, for example, to a torsion surface that is metrologically observed or monitored by means of the pickup unit. Accordingly, a rotary measuring section is set up in a way that is coordinated with the rotation of the pedal crankshaft and the operation of an electric bicycle and follows a predetermined radial course.

According to a preferred embodiment of the drive device, the chainring system comprises a chainring and a chainring spider, which are coupled to one another and to the pedal crankshaft by means of a motor output shaft. The pickup unit is arranged between the chainring and the engine output shaft. In this way, an area in the drive device that usually remains unused can be used specifically for the torque sensor unit or the pickup unit. A particularly space-saving design of the drive device can thus be implemented.

According to a further preferred embodiment of the drive device is the radial Measuring range formed in or on the chain ring spider. The measuring area can be arranged as a section to be measured on the spider or also as a torsion surface, which at least partially extends radially along a predetermined segment of a circle, integrated with the spider.

The chainring spider, or in short the spider, is usually a multi-armed component on which one or more chainrings are mounted. The spider thus forms a coupling element between a chainring and the pedal crankshaft. For example, it is pressed together with other components or designed as an integral part of a crank. In addition to the elements described, the chainring system can therefore also have a plurality of chainrings or gear-shaped elements coupled to one another.

According to a further preferred embodiment of the drive device, the pickup unit is arranged on the motor housing and is designed to be stationary in relation to the axis of rotation. Alternatively, the pickup unit is arranged on or in the chainring system, in particular the chainring spider, and is designed to be rotatable about the axis of rotation in relation to the axis of rotation.

Furthermore, the drive device can also include a stationary and a rotary mounted pickup unit.

According to a further preferred embodiment of the drive device, the pick-up electronics comprise a plurality of coils, which are arranged in a pick-up housing at a distance from the measuring area, so that a torque of the chain ring system can be measured without contact on the basis of magnetostriction. Thus, the torque sensor unit preferably comprises a magneto-restrictive torque sensor, which enables the torque to be detected in a robust, durable and maintenance-friendly manner, which can also be carried out very precisely and without wear.

To measure force based on magnetostriction, the pick-off unit is used to measure torsion or mechanical stress that acts on the element with the radial measuring area, thereby enabling an effective torque to be precisely determined. Magnetostriction can be explained, for example, as a deformation of magnetic materials as a result of a magnetic field and leads to an elastic change in geometry of the material or the corresponding body. For example, the measuring area is provided as a torsion surface of the chain ring spider, which is magnetically encoded in a predetermined manner. An acting torque leads to geometric changes in the spider, which are accompanied by changes in the magnetic coding of the torsion surface. These changes can be measured and conclusions can be drawn about the torque. Accordingly, the spider is magnetically passive and the measuring pickup unit is magnetically active.

The magnetostrictive torque sensor, for example, is a few tenths of a millimeter away from the measuring area and allows contactless measurement due to the magnetic field distortions. Such a torque detection is accompanied by no mechanical, thermal and/or chemical stress and also does not require any additional measuring elements, such as strain gauges, which can fall off over time. In addition, however, the torque sensor unit can also be provided with a conventional torque sensor in the drive device described.

According to a further preferred embodiment of the drive device, the pickup unit is coupled to an energy source in a wired and/or wireless manner for the electrical supply of the pickup electronics. For example, the drive device has an energy store in the form of a battery for the electrical supply of the consumer electronics. The battery is preferably implemented as an accumulator and is rechargeable. Thus, the torque sensor unit can be operated independently and does not require a wired power supply from the outside.

According to a further preferred embodiment of the drive device, the torque sensor unit comprises an induction unit, which is energetically coupled to the pickup unit in order to supply it with electricity. Accordingly, an electrical supply can be set up wirelessly or wirelessly and contribute to a clear structure. For example, the induction unit has a stationary induction coil and a rotary or rotatably mounted induction coil with respect to the axis of rotation. The stationary induction coil can be coupled to the motor housing and can be arranged, for example, on an outside of the motor housing that faces the chainring system. The rotary induction coil is then coupled, for example, to the chainring system, in particular the chainring spider, and faces the stationary induction coil. By moving the two induction coils relative to one another, energy for the electrical supply of the torque sensor unit can thus be provided on the basis of induction during operation of the electric bicycle.

According to a further preferred embodiment of the drive device, the pick-up electronics are set up to transmit a measurement signal, which is representative of a measured torque of the chainring system, by wire and/or wirelessly to motor electronics of the motor unit. A wired or cabled version can be provided, for example, if the pickup unit is designed to be stationary and is coupled to the motor housing. Cable or wireless data transmission is preferably implemented if the pick-up unit is designed to be rotatory and thus rotatable and is coupled to the chain ring spider, for example. Such wireless data transmission can be set up, for example, using Bluetooth or another near-field communication standard.

In addition to the electric motor, the motor housing of the drive device can accommodate a gear, which is designed, for example, as a belt gear or as a planetary gear. In particular, the electric motor and/or the transmission can be set up in such a way that they coaxially surround the pedal crankshaft with respect to the axis of rotation. The motor unit or the electric motor is designed, for example, as a ring motor and is arranged coaxially around the pedal crankshaft in relation to the axis of rotation of the same. The drive device can thus be designed to be particularly slim and space-saving. Furthermore, the pedal crankshaft can be designed in one piece or in several parts. For example, the pedal crankshaft is designed in two parts and has a first and a separate second partial element that are coupled to one another.

The described embodiments of the drive device each enable a compact and reliable electric drive system for an electric bicycle. The torque sensor unit monitors a relative movement of interlocking structures of the chainring system and enables safe operation of the electric bicycle with improved ride comfort.

In another aspect, an electric bicycle is disclosed having a bicycle frame with a lower frame portion that extends to a bottom bracket with a crank. The electric bicycle has a drive device according to one of the previously described embodiments, which is arranged in or on the frame section, so that the pedal crankshaft is coupled to the pedal crank. Essentially, the electric bicycle enables the aforementioned properties, advantages and functions.

For attachment to the frame section, the latter has a recess, for example, so that the drive device can be reliably accommodated. According to one embodiment, the drive device is arranged, in particular mounted, for example as an assembly in the already coupled state on the frame section.

The drive device enables an efficient and space-saving mechanical system to support cycling. This is made possible in particular by the externally arranged torque sensor unit, so that the drive device can be made significantly narrower in the area of the motor housing.

Thus, the preferably non-contact torque measurement takes place outside of the motor housing. Torque detection within the motor housing can therefore be saved, which is usually based on scanning a measuring shaft over the axial extent. Such an internal measurement requires a relatively complex arrangement of crankshaft freewheel measuring shaft in order to be able to measure the torques on both crank arms of the pedal crankshaft.

The drive device described can contribute to a clear structure, particularly in the motor housing, and the torque sensor unit can also be retrofitted to existing drive systems in order to form an embodiment of the drive device described. The drive device may include one or more torque sensors. Furthermore, the drive device can also have a speed sensor and/or other sensors that can contribute to comfortable operation of the electric bicycle.

• • Variante A: Messtrecke sitzt im/am Kettenblatt-Spider; die Abtastelektronik der Abnehmereinheit ist stationär an dem Motorgehäuse verbaut; Messsignale werden drahtgebunden an die Motorelektronik der Motoreinheit übertragen.
• • Variante B: Messstrecke sitzt im/am Kettenblatt-Spider und die Abtastelektronik der Abnehmereinheit ist an dem Kettenblatt-Spider angeordnet; Messsignale werden drahtlos an die Motorelektronik der Motoreinheit übertragen, elektrische Versorgung der Sensorelektronik der Abnehmereinheit erfolgt mittels einer Batterie.
• • Variante C: wie Variante B, aber eine elektrische Versorgung der Sensorelektronik der Abnehmereinheit erfolgt durch Induktion.
• • Variante D: wie Variante B, aber die elektrische Versorgung der Sensorelektronik der Abnehmereinheit erfolgt durch einen Schleifkontakt mittels einer radialen und/oder axialen Schleifkontaktierung.

The drive device is preferably designed according to one or more of the following variants:

• • Variant A: measuring section is in/on the chain ring spider; the scanning electronics of the pickup unit are installed stationary on the motor housing; Measurement signals are wired to the motor electronics of the motor unit.
• • Variant B: the measuring section is located in/on the chain ring spider and the scanning electronics of the pickup unit are arranged on the chain ring spider; Measuring signals are transmitted wirelessly to the motor electronics of the motor unit, the electrical supply of the sensor electronics of the pick-up unit is provided by a battery.
• • Variant C: like variant B, but the electrical supply of the sensor electronics of the pickup unit is provided by induction.
• • Variant D: like variant B, but the electrical supply of the sensor electronics of the pickup unit is provided by a sliding contact using a radial and/or axial sliding contact.

• - ein Bauraum in dem Motorgehäuse kann verringert werden.
• - eine radiale Erstreckung der Messstrecke ermöglicht besonders vorteilhaft, eine axiale Länge der Motoreinheit zu reduzieren.
• - aufwändige Messwellen und Schnittstellen innerhalb des Motorgehäuses entfallen.
• - eine Ausstattung der Antriebsvorrichtung mit der Drehmomentsensoreinheit oder der Abnehmereinheit ist optional ab Werk durchführbar oder sogar nachrüstbar.
• - verschiedene Sensorklassen sind für die Abnehmereinheit möglich und können an eine gewünschte Qualität und an vorgesehene Anwendungsbereiche angepasst werden: zum Beispiel kann ein relativ günstiger Street-Sensor, ein hochsensibler Trail-Sensor und/oder ein hochauflösender Road-Sensor für die Drehmomentsensoreinheit und die Abnehmereinheit vorgesehen werden.
• - Kostenersparnis in einer Grundkonfiguration der Antriebsvorrichtung ist auch ohne Sensor möglich.
• - Servicebarkeit und Wartungszugänglichkeit des Drehmomentsensors und der Abnehmereinheit sind ohne Öffnen der Motoreinheit durchführbar.
• - eine elektrische Versorgung kann mittels induktiver Spannungsversorgung erfolgen.
• - ein Weiterleiten von Messsignalen kann mittels drahtloser Datenübertragung erfolgen.

A comfortable and reliable electric drive system, preferably for a central motor, for electric bicycles can be implemented in particular in the embodiment of the torque sensor unit with a contactless torque sensor. The torque sensor or the pickup unit is integrated outside the motor housing between an output shaft and a chainring in the chainring spider of the chainring system. The intended measuring section extends radially around the axis of rotation. The drive device described enables one or more of the following advantages in its designs:

• - A space in the motor housing can be reduced.
• - A radial extent of the measuring section makes it particularly advantageous to reduce an axial length of the motor unit.
• - Complex measuring shafts and interfaces within the motor housing are no longer necessary.
• - An equipment of the drive device with the torque sensor unit or the pickup unit is optionally feasible ex works or can even be retrofitted.
• - Different sensor classes are possible for the pick-up unit and can be adapted to a desired quality and to the intended areas of application: for example, a relatively inexpensive street sensor, a highly sensitive trail sensor and/or a high-resolution road sensor for the torque sensor unit and the pick-up unit be provided.
• - Cost savings in a basic configuration of the drive device is also possible without a sensor.
• - Serviceability and maintenance accessibility of the torque sensor and the pickup unit can be carried out without opening the motor unit.
• - An electrical supply can take place by means of inductive voltage supply.
• - Measurement signals can be forwarded by means of wireless data transmission.

• 1 eine schematische Ansicht eines Elektrofahrrads mit einer montierten Antriebsvorrichtung,
• 2-3 schematische Schnittdarstellungen eines Ausführungsbeispiels der Antriebsvorrichtung für das Elektrofahrrad in verschiedenen Ansichten,
• 4-5 schematische Schnittdarstellungen eines weiteren Ausführungsbeispiels der Antriebsvorrichtung für das Elektrofahrrad in verschiedenen Ansichten,
• 6-7 schematische Schnittdarstellungen eines weiteren Ausführungsbeispiels der Antriebsvorrichtung für das Elektrofahrrad in verschiedenen Ansichten, und
• 8 schematische Schnittdarstellung eines weiteren Ausführungsbeispiels der Antriebsvorrichtung für das Elektrofahrrad.

Embodiments, advantages and functions are explained in the following description using exemplary embodiments with the aid of the attached figures. In the figures show:

• 1 a schematic view of an electric bicycle with a mounted drive device,
• 2-3 schematic sectional views of an embodiment of the drive device for the electric bicycle in different views,
• 4-5 schematic sectional views of another embodiment of the drive device for the electric bicycle in different views,
• 6-7 schematic sectional representations of a further embodiment of the drive device for the electric bicycle in different views, and
• 8th schematic sectional view of another embodiment of the drive device for the electric bicycle.

Identical, similar or equivalent elements are provided with the same reference symbols in the figures. For reasons of clarity, not all of the elements shown are identified with associated reference symbols in all of the figures.

1 shows schematically an electric bicycle 1 with a bicycle frame 2, which has, among other things, a lower frame section 3, which forms a down tube. The frame section 3 extends in the direction of a bottom bracket, which includes a pedal crank 4 that is coupled or can be coupled to an electric drive device 5 for the electric bicycle 1 .

Based on the following 2-8 , which schematically illustrate exemplary embodiments of the drive device 5, it is explained that the respective drive device 5 enables a reliable drive concept for electric bicycles, which can be implemented with a space-saving and maintenance-friendly structure. The drive device 5 comprises a motor unit with an electric motor (not shown in the figures) for driving the electric bicycle 1, which is arranged in a motor housing 7. The drive device 5 also has a pedal crankshaft 6 which can be rotated about an axis of rotation R and which extends through the motor housing 7 . The drive device 5 also has a chain wheel system 11 which is coupled to the pedal crankshaft 6 in order to drive the electric bicycle 1 . In addition, the drive device 5 comprises a torque sensor unit 10 which, in relation to the axis of rotation R, is outside of the motor housing 7 between the chains sheet system 11 and the motor housing 7 is arranged.

The chainring system 11 comprises a chainring 12 and a chainring spider 13 which are coupled to one another and to the pedal crankshaft 6 by means of an output shaft 8 . The torque sensor unit 10 is arranged externally to the motor housing 7 between the chain ring 12 and the output shaft 8 . To measure a torque of chainring system 11, torque sensor unit 10 comprises a pick-up unit 14 with pick-up electronics 16 and a radial measuring area 20, which are aligned such that a measuring direction between pick-up unit 14 and radial measuring area 20 is formed predominantly along the axis of rotation R.

The radial measuring area 20 is designed as a torsion surface in or on the chain ring spider 13 and faces the pickup unit 14 . The measurement area 20 extends around the axis of rotation R and can completely encircle it or can also be designed to be predetermined only in sections on a segment of a circle. Correspondingly, the pick-up unit 14 can be ring-shaped and form a self-contained measuring ring or be designed as a ring section. The radial measurement area 20 forms the section to be measured in order to determine a torque that acts on the chainring system 11 when the electric bicycle 1 is in operation. The measurement area 20 is observed or monitored by means of the pick-up unit 14 and the rotary measurement section is measured cyclically or continuously when the electric bicycle 1 is in operation.

the 2 and 3 show a perspective view and a side view of a respective sectional view through an exemplary embodiment of the drive device 5 . When the electric bicycle 1 is in operation, the chainring 12 and the chainring spider 13 rotate past the stationary pick-up unit 14 and enable torque to be determined.

The pick-up electronics 16 include, for example, a plurality of coils, which are arranged in a pick-up housing 15 at a distance from the measuring area 20, so that a torque of the chainring system 11 can be measured without contact on the basis of magnetostriction. Thus, the torque sensor unit 10 preferably comprises one or more magnetostrictive torque sensors. To measure force based on magnetostriction, the pickup unit 14 is used to measure a torsion or mechanical stress that acts on the chain ring spider 13 and the radial measuring area 20 formed thereon, thereby enabling a precise and contact-free determination of an acting torque.

the 4 and 5 show a perspective view and a side view of a respective sectional view through a further exemplary embodiment of the drive device 5. The pickup unit 14, like the measuring area 20, is also designed to be rotatory and is arranged on or in the chain ring 12 and/or the chain ring spider 13. The torque sensor unit 10 is thus integrated in the chainring system 11 and rotates with it around the axis of rotation R when the electric bicycle 1 is in operation.

the 6 and 7 show a perspective view and a side view of a respective sectional view through a further exemplary embodiment of the drive device 5. The pickup unit 14 is, as in the previous exemplary embodiment according to FIGS 4 and 5 , designed to rotate and arranged in or on the chain ring 12 and/or the chain ring spider 13 . The torque sensor unit 10 also includes an induction unit 17 which provides an inductive electrical supply to the pickup unit 14 .

The induction unit 17 is arranged between the motor housing 7 and the chain ring system 11 and has a stationary induction coil 18 and a rotary induction coil 19 with respect to the axis of rotation R. The stationary induction coil 18 is arranged on an outside of the motor housing 7 and faces the pickup unit 14 . The rotary induction coil 19 is coupled to the chain ring system 11 and is arranged on the pickup unit 14 or is designed to be integrated into it. For example, the rotary induction coil 19 is preset in the pickup case 15 to face the stationary induction coil 18 . Like the pick-up unit 14, the induction unit 17 can thus advantageously use a free space that is usually present between the motor housing 7 and the chainring system 11.

The pick-up electronics 16 of the drive device 5 are also set up to transmit a measurement signal, which is representative of a measured torque of the chainring system 11, to motor electronics of the motor unit by wire and/or wirelessly.

According to the illustrated exemplary embodiments, the radial measuring section is located in or on the chain ring spider 13 2 and 3 installed stationary on the motor housing 7 be. Measurement signals for determining the torque can then be transmitted by wire, for example, to engine electronics of the engine unit.

Alternatively, the scanning electronics of the pickup unit 14 according to the 4 and 5 be arranged rotatably on the chain ring 12 and/or the chain ring spider 13 . Measurement signals are then preferably transmitted wirelessly to the motor electronics of the motor unit, and the pick-up unit 14 is supplied with electricity, for example by means of a rechargeable battery.

Alternatively or additionally, an electrical supply of the pickup unit 16 according to 6 and 7 be done by induction. In addition, the drive device 5 can have an intermediate store that can be charged, for example, by means of induction and that provides a power supply for the pickup electronics 16 of the pickup unit 14 .

8th shows a further possible embodiment of the drive device 5, which illustrates an alternative or additional possibility for the electrical supply of the pickup unit 16, which is based on a slip ring contact 21. The slip ring contact 21 is set up by a slip ring element 22 which is configured in a predetermined manner in coordination with the pickup unit 14 . The slip ring element 22 comprises one, two or more flat slip rings having a contact material with silver or gold, for example, facing the pickup housing 15 . In this way, the electrical supply of the pickup electronics 16 of the pickup unit 14 can be provided by a radial and/or axial sliding contact with the pickup housing 15 set up for this purpose.

A reliable drive concept for electric bicycles can be implemented by means of the described configurations of the drive device 5, which enables a special and space-saving design. The respective drive device 5 is suitable in particular for mounting on a down tube or on a seat tube of the electric bicycle 1 and enables an advantageous drive system, in particular with regard to high efficiency, small size and improved driving comfort.

Reference List

1

electric bike

2

bike frame

3

frame section

4

crank

5

drive device

6

pedal crankshaft

7

motor housing

8th

engine output shaft

10

torque sensor unit

11

chainring system

12

chainring

13

Chainring Spider

14

pickup unit

15

pickup housing

16

pickup electronics

17

induction unit

18

stationary induction coil

19

rotary induction coil

20

measuring range

21

slip ring contact

22

slip ring element

R

Axis of rotation of the pedal crank / pedal crankshaft

Claims (12)

Drive device (5) for an electric bicycle (1), having: - a motor unit with an electric motor for driving the electric bicycle (1), which is arranged in a motor housing (7), - a pedal crankshaft (6) which is rotatable about an axis of rotation (R) and extends through the motor housing (7), - a chain ring system (11) which is coupled to the pedal crankshaft (6) for driving the electric bicycle (1), and - a torque sensor unit (10) which is arranged with respect to the axis of rotation (R) outside the motor housing (7) between the chainring system (11) and the motor housing (7) and which has a pickup unit ( 14) with pick-up electronics (16) and a radial measuring area (20) which are aligned in such a way that a measuring direction between the pick-up unit (14) and the radial measuring area (20) is formed along the axis of rotation (R). Drive device (5) after claim 1 , in which the chainring system (11) comprises a chainring (12) and a chainring spider (13) which are coupled to one another and to the pedal crankshaft (6) by means of a motor output shaft (8), the pickup unit (14) between the chainring (12) and the motor output shaft (8) is arranged. Drive device (5) after claim 2 , in which the radial measuring area (20) is formed in or on the chain ring spider (13). Drive device (5) according to one of the preceding claims, in which the pickup unit (14) is arranged on the motor housing (7) and is designed to be stationary in relation to the axis of rotation (R). Drive device (5) according to one of Claims 1 until 3 In which the pickup unit (14) is arranged on or in the chainring system (11) and is designed to be rotatable about the axis of rotation (R) in relation to the latter. Drive device (5) according to one of the preceding claims, in which the pick-up electronics (16) comprises a plurality of coils which are arranged in a pick-up housing (15) at a distance from the measuring area (20), so that a torque of the chain ring system (11) is based on of magnetostriction can be measured without contact. Drive device (5) according to one of the preceding claims, in which the pickup unit (14) for the electrical supply of the pickup electronics (16) is coupled to an energy source in a wired and/or wireless manner. Drive device (5) after claim 7 , In which the pickup unit (14) comprises an energy store for the electrical supply of pickup electronics (16). Drive device (5) according to one of the preceding claims, in which the torque sensor unit (10) comprises an induction unit (17) which is energetically coupled to the pickup unit (14) in order to supply it with electricity. Drive device (5) after claim 9 , in which the induction unit (17) has a stationary induction coil (18) and a rotary induction coil (19) with respect to the axis of rotation (R), the stationary induction coil (18) being connected to the motor housing (7) and the rotary induction coil (19 ) is coupled to the chain ring system (11). Drive device (5) according to one of the preceding claims, in which the pickup electronics (16) is set up to transmit a measurement signal, which is representative of a measured torque of the chainring system (11), by wire and/or wirelessly to motor electronics of the motor unit. Electric bicycle (1) having: - a bicycle frame (2) having a lower frame portion (3) extending to a bottom bracket having a crank (4), and - A drive device (5) according to any one of the preceding claims, which is coupled to drive the electric bicycle (1) to the bicycle frame (2), so that the crankshaft (6) is coupled to the crank (4).

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