DE102023204103B3 - Freewheel device for a drive train of a bicycle and bicycle with such a freewheel device - Google Patents

Abstract

The invention relates to a freewheel device for a drive train of an at least partially electrically powered bicycle, comprising: a first ring (1), a second ring (2) arranged coaxially to the first ring (1), a cage (3) arranged coaxially to the two rings with a plurality of clamping bodies (4) arranged radially between the two rings, which are arranged in a first relative direction of rotation between the two rings for the rotationally fixed connection of the two rings and in a second relative direction of rotation between the two rings for the decoupling of the two rings and activation of a freewheel function, a disk (5) arranged rotationally fixed on the cage (3), which is positively connected to the first ring (1), the positive connection being designed with play such that the cage (3) can rotate to a limited extent relative to the first ring (1) in order to activate the freewheel function, a pedal crankshaft (6) connected rotationally fixed to the first ring (1) for introducing a drive power generated by muscle power, a sensor element for detecting a torque on the first ring (1) and generating corresponding sensor data, wherein the sensor element is arranged on the first ring (1) and is designed to transmit the sensor data to a control device in order to control an electric machine in the drive train of the bicycle in accordance with the sensor data.

Description

The present invention relates to a freewheel device for a drive train of a bicycle, wherein at least one electric drive motor is arranged in the drive train. The invention further relates to a bicycle with such a freewheel device.

Bicycles are generally known that can be powered by an electric machine in addition to the drive power of a cyclist. Such bicycles are also known as electric bicycles, pedelecs or e-bikes. The cyclist's drive power is usually supported by the electric machine in accordance with the cyclist's wishes and the torque supplied by the cyclist. The electric machine can be arranged as a mid-engine in the area of the pedal crankshaft or as a wheel drive directly on the respective drive wheel.

For example, the EN 10 2019 220 047 B4 a freewheel clutch that is intended for use in an electric bicycle. The freewheel clutch comprises a first and a second shaft that are arranged coaxially to one another and are mounted so that they can rotate relative to one another about a common axis of rotation, a plurality of clamping bodies that are arranged radially between the two shafts, and at least one electromagnet. In a locking position, the clamping bodies connect the two shafts to one another in a rotationally fixed manner. In a freewheel position, the clamping bodies allow the two shafts to rotate relative to one another. Since this freewheel clutch is switchable, the locking position and the freewheel position of the clamping bodies depend on the direction of rotation and the speed of the two shafts.

EN 10 2016 122 845 A1 discloses a load cell for determining a radial force on a crankshaft with a receiving sleeve for receiving a bearing ring and a fastening ring for fastening the load cell in a transmission housing. Axial support areas are provided on the fastening ring for axially supporting the outer ring of the first bearing. Furthermore, measuring areas are provided for receiving radial forces of the receiving sleeve, which connect the receiving sleeve to the fastening ring. Strain sensors are attached to at least two of the measuring areas.

EN 10 2021 213 506 B3 discloses an electric drive device for a bicycle, wherein the electric drive device comprises an electric motor, a pedal crankshaft, at least one switchable freewheel and an actuator for actuating the switchable freewheel. The switchable freewheel enables an interruption of a mechanical operative connection between the electric motor and the pedal crankshaft, wherein the switchable freewheel comprises at least one freewheel element which can be moved between a locking position and a freewheel position. The actuator comprises a housing and an actuating ring arranged in the housing coaxially to the freewheel so that it can rotate. The actuating ring has at least two grooves which extend radially inwards in an arc shape. The actuator also comprises two slats which are rotatably mounted on the housing and which are each rotatably guided in one of the two grooves. The two slats are designed to engage with the one freewheel element when the actuating ring rotates, so that the at least one freewheel element can be moved between the locking position and the freewheel position.

The present invention is based on the object of creating a freewheel device for an electric bicycle that has improved torque measurement. In particular, the freewheel device should be designed to be compact. The object is achieved by the objects with the features of the independent patent claims. Further advantageous embodiments can be found in the dependent claims.

A freewheel device according to the invention for a drive train of an at least partially electrically powered bicycle comprises a first ring, a second ring arranged coaxially to the first ring, a cage arranged coaxially to the two rings with a plurality of clamping bodies arranged radially between the two rings, which are arranged in a first relative direction of rotation between the two rings for the rotationally fixed connection of the two rings and in a second relative direction of rotation between the two rings for the decoupling of the two rings and activation of a freewheel function, a disk arranged in a rotationally fixed manner on the cage, which is positively connected to the first ring, wherein the positive connection is designed with play such that the cage can rotate to a limited extent relative to the first ring in order to activate the freewheel function, a pedal crankshaft connected in a rotationally fixed manner to the first ring for introducing a drive power generated by a cyclist's muscle power into the freewheel device, and at least one sensor element for detecting a torque on the first ring and generating corresponding sensor data, wherein the at least one sensor element is arranged on the first ring and designed to To transmit sensor data to a control device in order to control an electrical machine in to control the bicycle’s drive train according to this sensor data.

In other words, the at least one sensor is designed to identify a driver request with regard to the drive power initiated via the pedals when the support from the electric machine is switched on and to use this to adapt the control of the electric machine. The drive power of the electric machine can therefore be dosed using the torque that is recorded on the first ring and depends on the torque that the cyclist applies to the pedals. The more torque the cyclist applies to the pedals, the greater the drive power provided by the electric machine, which is designed to support the cyclist's drive power. The pedals are connected to the crankshaft via pedal cranks.

The freewheel device decouples the crankshaft, depending on the riding situation. In a first relative direction of rotation between the two rings, for example when the cyclist pedals forwards, a locking function is active on the freewheel device, whereby the two rings are connected to one another in a rotationally fixed manner via the clamping bodies in the cage. The rotationally fixed connection of the two rings by means of the clamping bodies is force-locking. In a second relative direction of rotation between the two rings, for example when the cyclist pedals backwards, a freewheel function is active on the freewheel device, whereby the clamping bodies in the cage tilt and thereby cancel the force-locking connection between the two rings.

By arranging the at least one sensor element in the immediate vicinity of the pedal crankshaft or on the pedal crankshaft, the torque detection and thus also the control of the electric machine are improved. Furthermore, by integrating the at least one sensor element into the first ring and the coaxial arrangement of the rings and the cage, not only the torque detection and thus also the control of the electric machine is further improved, but also installation space is saved and the degree of compactness is increased. The two rings and the cage are preferably arranged concentrically to one another.

Preferably, the disk is formed monolithically with the cage. In particular, the pedal crankshaft is formed monolithically with the first ring. This reduces the torque detection, in particular disturbances caused by connection points, and thus also further improves the control of the electric machine.

The first ring is provided as a deformation component that is used for torque measurement. The first ring is preferably designed as an inner ring, with the second ring being designed as an outer ring. Alternatively, a reverse arrangement is also conceivable, so that the first ring is designed as an outer ring and the second ring as an inner ring.

For example, a common spring element is arranged all around the cage to position all the clamping bodies, whereby the clamping bodies tilt or stand up in the cage to ensure a rotationally fixed connection of the two rings in such a way that a torque-dependent radial force is introduced into the two rings via the clamping bodies. In particular, the spring element is designed as a worm spring and is intended to position the clamping bodies in the locking position. In the locking position, the radial force acts inwards on the outer peripheral surface of the inner ring and causes the inner ring to be compressed, whereby the radial force is directed outwards on the inner peripheral surface of the outer ring and causes the outer ring to be stretched. To initiate the freewheel function, the spring force of the spring element is counteracted.

By coupling the cage to the first ring, torque measurement can be improved because a relative movement, in particular a rotation of the cage with the clamping bodies relative to the first ring on which the torque measurement technology, i.e. the at least one sensor element, is arranged, is avoided. Because the cage with the clamping bodies is forced to rotate with the first ring, the clamping pattern by the clamping bodies on the first ring is always identical, so that related disruptive forces, in particular radial forces migrating around the circumference, are avoided.

According to a preferred embodiment, several axially formed pins are arranged on the disk, wherein the respective pin penetrates at least partially into a respective bore on the first ring. In particular, the respective pin and the respective bore are cylindrical. The outer surface of the respective bore is provided as a stop surface for the outer surface of the respective pin. The pins arranged in the bores form the positive connection with play between the disk and the first ring.

According to a preferred embodiment, an elastic damping element is arranged on at least one pin for positioning the cage relative to the first ring, wherein the elastic damping element is arranged between the bore on the first ring and the pin. Before An elastic damping element is arranged on each pin. The respective elastic damping element is intended for elastic deformation with a limited relative rotation between the cage and the first ring. This results in a coupling of the cage to the first ring with low rigidity in order not to significantly influence the positioning of the clamping pieces. This enables small compensating movements of the cage and at the same time avoids a larger relative rotation due to the positive stop. For example, the damping element is designed as a spring or from an elastically springy material.

According to a preferred embodiment, the elastic damping element is ring-shaped and made of an elastomer material and is arranged all around the pin. In particular, the elastic damping element is designed as an O-ring. This makes it easier to mount the elastic damping element on the pin. Preferably, the ring-shaped, elastic damping element is arranged in a circumferential groove on the respective pin. This further makes it easier to mount the elastic damping element on the pin.

According to a preferred embodiment, the respective bore has a diameter that is at most as large as the diameter of the damping element arranged on the pin. The diameter of the respective bore is preferably slightly smaller than the diameter of the damping element arranged on the pin, whereby there is a slight deformation and thus a pre-tension of the damping element. This in particular achieves self-centering between the first ring and the cage.

According to a preferred embodiment, the pins are arranged point-symmetrically to the center of the disk, with the holes being arranged point-symmetrically to the center of the first ring. Twelve pins are preferably arranged on the disk, with twelve holes being arranged in the first ring. Three pins are preferably arranged one after the other in the circumferential direction, with the respective set of three pins being arranged at a distance from another set of three pins. The holes in the first ring also have a corresponding arrangement. This advantageously designs the deformation pattern of the first ring. In particular, advantageous shear deformations can occur on the first ring, with sensor elements being arranged specifically in the area of these shear deformations on the first ring in order to improve torque detection and thus also the control of the electrical machine.

According to a preferred embodiment, at least two sensor elements designed as strain gauges are arranged evenly distributed in the circumferential direction on the first ring. For example, the at least two sensor elements are arranged on an end face or in a respective bore on the first ring. Sensor elements that are arranged on the end face of the first ring are preferably arranged in the circumferential direction between two bores. Even high radial forces occurring on the circumference of the first ring in the locking position of the freewheel device can be compensated by a symmetrical arrangement of the torque strips, in particular by forming a so-called full bridge. For example, four torque strips are arranged evenly distributed in the circumferential direction on the first ring.

A bicycle according to the invention comprises a freewheel device according to the invention and at least two wheels, with at least one of the wheels being designed as a drive wheel and being connected to at least one electric machine for driving purposes. The bicycle according to the invention therefore comprises the usual components of a bicycle that can be driven using muscle power. The electric machine can reduce the strain on the cyclist when moving or increase his range, depending on the capacity of the energy storage device connected to it. The above definitions and statements on technical effects, advantages and advantageous embodiments of the freewheel device according to the invention also apply mutatis mutandis to the bicycle according to the invention.

• 1 eine stark vereinfachte schematische Darstellung eines Fahrrads mit einer erfindungsgemäßen Freilaufvorrichtung,
• 2 eine vereinfachte schematische Explosionsdarstellung der erfindungsgemäßen Freilaufvorrichtung,
• 3 eine vereinfachte schematische Perspektivdarstellung der erfindungsgemäßen Freilaufvorrichtung, und
• 4 eine vereinfachte schematische Perspektivschnittdarstellung der erfindungsgemäßen Freilaufvorrichtung.

In the following, a preferred embodiment of the invention is explained in more detail with reference to the figures, wherein identical or similar elements are provided with the same reference numerals.

• 1 a highly simplified schematic representation of a bicycle with a freewheel device according to the invention,
• 2 a simplified schematic exploded view of the freewheel device according to the invention,
• 3 a simplified schematic perspective view of the freewheel device according to the invention, and
• 4 a simplified schematic perspective sectional view of the freewheel device according to the invention.

In 1 A bicycle 100 according to the invention is shown in a highly simplified manner. The bicycle 100 has a frame 104 on which a rear wheel designed as a drive wheel 102, a front wheel 103, a bicycle handlebar 105 and a saddle 106 are arranged. The bicycle 100 also has a drive device which is designed to drive the bicycle 100 at least with the muscle power of a cyclist (not shown here). To do this, the cyclist sits on the saddle 106 when riding, for example, and introduces drive power into the drive train of the bicycle 100 via respective pedals 107, which are connected to a pedal crankshaft 6 of the drive device via respective pedal cranks. The drive device 1 also includes a drive machine designed as an electric machine 101, which is arranged as a mid-engine in the area of the pedal crankshaft 6 and can in turn also introduce drive power into the drive train of the bicycle 100 in order to assist the cyclist when riding. The bicycle 100 is therefore designed as an e-bike. In the present case, the drive power is transmitted to the drive wheel via a traction drive 108 with two sprockets and a chain. The pedal crankshaft 6 can be decoupled from the drive train via a freewheel device 50. A key requirement for drive devices for e-bikes is that they have as compact a design as possible. This requires a dense arrangement of the functional elements. Key functional elements in a drive device for e-bikes are the torque measurement technology for detecting the driver's request and controlling the electric machine, as well as the freewheel device itself, which, depending on the driving situation, enables the pedal crankshaft 6 to be decoupled.

In 2 , 3 and 4 the freewheel device 50 is made of 1 The freewheel device 50 comprises a first ring 1, a second ring 2 arranged coaxially to the first ring 1 and a cage 3 arranged coaxially to the two rings 1, 2 with a plurality of clamping bodies 4 arranged radially between the two rings 1, 2. The pedal crankshaft 6, which is designed to introduce a drive power generated by the cyclist's muscle power into the freewheel device 50, is monolithically connected to the first ring 1. The first ring 1 is designed as an inner ring. The second ring 2 is designed as an outer ring. The two rings 1, 2 and the cage 3 rotate about a common axis of rotation R and are, as can be seen in particular from 3 and 4 , arranged concentrically to one another. A disk 5 is formed on the cage 3 and is connected in one piece to the cage 3. A plurality of axially formed pins 8 are arranged on the disk 5, each pin 8 penetrating at least partially into a respective bore 9 provided for it on the first ring 1. As a result, the disk 5 and thus also the cage 3 are positively connected to the first ring 1. The positive connection is designed with play such that the cage 3 can rotate to a limited extent relative to the first ring 1 in order to activate a freewheel function.

An elastic damping element 10 is arranged on each pin 8 for positioning the cage 3 relative to the first ring 1. The respective elastic damping element 10 is ring-shaped and made of an elastomer material and is arranged circumferentially on the respective pin 8. The respective elastic damping element 10 thus comes to rest with an outer circumferential surface on the respective bore 9 and with an inner circumferential surface on the respective pin 8. As can be seen from 4 As can be seen, the respective elastic damping element 10 is arranged in a circumferential groove on the respective pin 8. Furthermore, the respective bore 9 has a diameter that is slightly smaller than the diameter of the damping element 10 arranged on the pin 8. As a result, when the pins 8 are pushed into the bores 9, the cage is centered relative to the first ring 1 and is elastically preloaded in the circumferential direction. The cage 3 can rotate to a limited extent relative to the first ring 1 in order to activate the freewheel function, namely until a maximum deformation of the damping elements 10 is reached.

According to a first relative direction of rotation between the two rings 1, 2, the clamping bodies 4 in the cage 3 are tilted or positioned radially in such a way that the two rings 1, 2 are connected via the clamping bodies 4 in a force-fitting and thus rotationally fixed manner. In this case, a torque-dependent radial force is introduced into the two rings 1, 2 via the clamping bodies 4. The freewheel device 50 is therefore then in the locked state. According to a second relative direction of rotation between the two rings 1, 2, which is opposite to the first relative direction of rotation, the clamping bodies 4 in the cage 3 are tilted in such a way that the two rings 1, 2 are decoupled from one another via the clamping bodies 4 and, as long as the second relative direction of rotation is maintained, can rotate independently of one another. The freewheel device 50 therefore then has a freewheel function. A common spring element 11 is arranged circumferentially in the cage 3 for positioning all clamping bodies 4.

In the present case, two sensor elements 7a, 7b are provided for detecting a torque on the first ring 1 and for generating corresponding sensor data. The sensor data are transmitted to a control device (not shown) in order to control the electric machine 101 in the drive train of the bicycle 100 in accordance with these sensor data in a known manner. The two sensor elements 7a, 7b are designed as strain gauges and are arranged evenly distributed in the circumferential direction on the first ring 1. In the present case, the two Sensor elements 7a, 7b are arranged between two holes 9 on an end face of the first ring 1. This allows a particularly precise torque measurement to be carried out. In addition, twelve pins 8 are formed on the disk 5 and twelve holes in the first ring 1. The pins 8 are arranged point-symmetrically to the center of the disk 5. The holes 9 are arranged point-symmetrically to the center of the first ring 1. This can also improve torque measurement.

In the present case, three pins 8 are arranged one after the other in the circumferential direction, with the respective package of three pins 8 being arranged at a distance from another package of three pins. The holes 9 in the first ring 1 also have a corresponding arrangement. This advantageously shapes the deformation pattern of the first ring 1.

Reference symbols

1

first ring

2

second ring

3

Cage

4

Clamp body

5

disc

6

Crankshaft

7a, 7b

Sensor element

8th

cone

9

drilling

10

Damping element

11

Spring element

50

Freewheel device

100

Bicycle

101

electric machine

102

drive wheel

103

Front wheel

104

Frame

105

Bicycle handlebars

106

saddle

107

Pedals

108

Traction drive

R

Rotation axis

Claims (10)

Freewheel device (50) for a drive train of an at least partially electrically powered bicycle (100) comprising • a first ring (1), • a second ring (2) arranged coaxially to the first ring (1), • a cage (3) arranged coaxially to the two rings (1, 2) with a plurality of clamping bodies (4) arranged radially between the two rings (1, 2), which are arranged in a first relative direction of rotation between the two rings (1, 2) for the rotationally fixed connection of the two rings (1, 2) and in a second relative direction of rotation between the two rings (1, 2) for the decoupling of the two rings (1, 2) and activation of a freewheel function, • a disk (5) arranged rotationally fixed on the cage (3), which is positively connected to the first ring (1), wherein the positive connection is designed with play, whereby the cage (3) can rotate to a limited extent relative to the first ring (1) in order to activate the freewheel function, • a pedal crankshaft (6) connected in a rotationally fixed manner to the first ring (1) for introducing a drive power generated by a cyclist's muscle power into the freewheel device (50), and • at least one sensor element (7a) for detecting a torque on the first ring (1) and generating corresponding sensor data, wherein the at least one sensor element (7a) is arranged on the first ring (1) and is designed to transmit the sensor data to a control device in order to control an electric machine (101) in the drive train of the bicycle (100) in accordance with the sensor data. Freewheel device (50) according to Claim 1 , wherein a plurality of axially formed pins (8) are arranged on the disc (5), wherein the respective pin (8) at least partially penetrates into a respective bore (9) on the first ring (1). Freewheel device (50) according to Claim 2 , wherein an elastic damping element (10) is arranged on at least one pin (8) for positioning the cage (3) relative to the first ring (1), wherein the elastic damping element (10) is arranged between the bore (9) on the first ring (1) and the pin (8). Freewheel device (50) according to Claim 3 , wherein the elastic damping element (10) is ring-shaped and made of an elastomer material and is arranged circumferentially on the pin (8). Freewheel device (50) according to Claim 3 or 4 , wherein the respective bore (9) has a diameter which is at most as large as a diameter of the damping element (10) arranged on the pin (8). Freewheel device (50) according to one of the Claims 2 until 5 , wherein the pins (8) are arranged point-symmetrically to the center of the disc (5), wherein the bores (9) are arranged point-symmetrically to the center of the first ring (1). Freewheel device (50) according to one of the preceding claims, wherein at least two sensor elements (7a, 7b) designed as torque strips are arranged on the first ring (1) evenly distributed in the circumferential direction. Freewheel device (50) according to one of the preceding claims, wherein a common spring element (11) for positioning all clamping bodies (4) is arranged circumferentially in the cage (3), wherein the clamping bodies (4) tilt in the cage (3) for the rotationally fixed connection of the two rings (1, 2) in such a way that a torque-dependent radial force is introduced into the two rings (1, 2) via the clamping bodies (4). Freewheel device (50) according to one of the preceding claims, wherein the first ring (1) is designed as an inner ring, wherein the second ring (2) is designed as an outer ring. Bicycle (100) with an electric machine (101) and a freewheel device (50) according to one of the preceding claims.