Drive assembly of a vehicle which can be driven by muscle power and / or motor power

Abstract

The invention relates to a drive assembly (1) of a vehicle (100) which can be driven by muscle power and / or motor power, in particular an electric bicycle, comprising a crankshaft (22d) which is designed to be rotationally fixed to cranks (21) of a crank drive (2), an output shaft (22) comprising an output interface (35) which is designed to be connected to an output element (3), a freewheel (6) between the output shaft (22) and the crankshaft (22d), at least one bearing (24), by means of which the output shaft (23) is supported, at least one bearing force sensor (51, 52), in particular two bearing force sensors (51, 52), said bearing force sensor (51, 52) being designed to detect a force (55, 56), and a detection unit (54) which is designed to detect a bearing force (59) on the bearing (24) on the basis of the force (55, 56) detected by the bearing force sensor (51, 52).

Description

[0001] Description

[0002] title

[0003] Drive arrangement of a vehicle that can be operated with muscle power and / or motor power

[0004] State of the art

[0005] The present invention relates to a drive arrangement of a vehicle operable with muscle power and / or motor power, a vehicle operable with muscle power and / or motor power comprising the drive arrangement, and a method for operating a drive arrangement.

[0006] Drive arrangements for vehicles that can be operated using muscle power and / or motor power, such as electric bicycles, are known. These vehicles have a drive unit that can generate motor torque to assist the pedaling force of a rider of the vehicle. Typically, the motor torque is generated as a function of the rider torque generated by the rider's muscle power. This requires recording the value of the currently generated rider torque, for example, using appropriate sensors. It is also known, for example, that based on a bearing force on a bearing of the electric bicycle, information can be obtained about a force exerted by a rider on the pedal operation, and that the drive unit can be actuated based on this force. Such a system is shown, for example, in DE 102010 001 775 A1.

[0007] Disclosure of the invention

[0008] The drive assembly according to the invention with the features of claim 1 is distinguished by the fact that a bearing force on a bearing of a vehicle operable with muscle power and / or motor power can be precisely determined in a particularly simple and cost-effective manner. Furthermore, a simple determination of the bearing force can be made possible, for example, independently of the orientation of a motor, for example, on a bicycle frame of an electric bicycle. Based on the bearing force thus determined, further functions of the drive assembly can advantageously be provided efficiently and cost-effectively.This is achieved by a drive arrangement of a vehicle operable with muscle power and / or motor power, preferably an electric bicycle, comprising a crankshaft, an output shaft, a freewheel, at least one bearing by means of which the output shaft is mounted, at least one bearing force sensor, in particular two bearing force sensors, and a detection unit. The crankshaft is designed for connection, in particular in a rotationally fixed manner, to cranks of a crank drive. The output shaft has an output interface, wherein the output interface is designed for connection to an output element. Such an output element can preferably be a chainring. Alternatively, another output element can preferably be provided, which is designed for connection to a transmission element in order to enable torque transmission from the output shaft to a drive wheel of the vehicle.The freewheel is arranged between the output shaft and the crankshaft. In particular, the freewheel is configured to switch between a rotationally fixed connection and a relatively freely rotatable connection between the output shaft and the crankshaft. The bearing is provided for supporting the output shaft. In addition, each bearing force sensor is configured to detect a force. In particular, the two bearing force sensors are arranged at different circumferential positions relative to the output shaft. The detection unit is configured to detect a bearing force on the bearing based on the force detected by the bearing force sensor, in particular the forces detected by the bearing force sensors.

[0009] The freewheel preferably locks in the drive direction of the crankshaft, i.e., in particular, the freewheel allows torque to be transmitted from the crankshaft to the output shaft when the crankshaft is rotated in a predetermined forward direction of rotation relative to the output shaft. Furthermore, the freewheel preferably opens when the crankshaft and output shaft rotate in opposite directions. In particular, the freewheel is thus provided in the form of a driver's freewheel. Bearing force is considered to be, in particular, a total resulting force in the area of ​​the bearing, which occurs, for example, due to an engine torque and / or a driver torque. Particularly preferably, the detection unit is configured to determine a bearing force direction and a bearing force magnitude of the bearing force on the bearing based on the forces detected by the bearing force sensors.

[0010] Preferably, each bearing force sensor is configured to detect a force, in particular exclusively, along a predetermined direction. Preferably, the two bearing force sensors are arranged in the axial direction of the output shaft at the level of the bearing.

[0011] In other words, a drive arrangement is provided which has two force sensors on the bearing. Because the two bearing force sensors are distributed around the circumference of the output shaft, measured values ​​for forces in two mutually different directions are determined. Preferably, this makes it easy to determine a bearing force direction and a bearing force magnitude of the instantaneous bearing force on the bearing. Preferably, this determination of the bearing force direction and the bearing force magnitude is based on a previously known relative installation position of the two bearing force sensors to one another, and in particular based on previously known measuring directions of the bearing force sensors along which the respective forces are measured.

[0012] Bearing force sensors can be used in a variety of ways, suitable for detecting mechanical forces acting in a predetermined direction. For example, the bearing force sensors can be designed to detect tensile and / or compressive forces.

[0013] For a particularly simple design, the two force sensors can preferably be identical in construction.

[0014] The drive arrangement thus offers the advantage of measuring the bearing force at the bearing using a particularly simple, cost-effective, and space-saving design. The use of force sensors, which can be characterized, for example, by particularly simple and lightweight designs that require little installation space, also allows for a particularly space-saving arrangement. Furthermore, the use of force sensors, which generally have little or no susceptibility to magnetic fields, enables particularly reliable and precise measurement of the bearing force.

[0015] A further advantage of the drive arrangement is that the direction and magnitude of the bearing force can be precisely determined regardless of the installation position of the drive unit on an electric bicycle. This means that the drive unit can be arranged on the bicycle frame of an electric bicycle in any orientation, particularly with respect to rotation around the bottom bracket axis. Due to the circumferentially offset arrangement of the two force sensors, the resulting bearing force can be precisely measured in any orientation of the drive unit without the need to adapt the arrangement of the force sensors to the installation position. The resulting bearing force can preferably be determined based on a simple, one-time calibration of the system.

[0016] The particularly space-saving design of the system for detecting the bearing force also enables a particularly advantageous design of the entire drive arrangement in terms of space utilization and power transmission, particularly in combination with the freewheel. For example, a flexible and at the same time particularly space-saving arrangement of the output shaft and crankshaft relative to one another can be provided. For example, a gearbox, by means of which, for example, engine torque can be transmitted from an engine to the output shaft, can be arranged flexibly and with the greatest possible space optimization. In particular, such a gearbox can be easily optimized with regard to a desired transmission ratio. In addition, an external geometry of the drive arrangement can be flexibly adapted in order to be able to provide, for example, an optimized frame geometry of a vehicle frame.For example, the maximum external dimensions of the drivetrain can be kept as compact as possible, allowing for a short chainstay length, which, in particular, allows for optimization of the vehicle's kinematics with regard to rear triangle geometry. Furthermore, the drivetrain is characterized by low cost due to fewer and relatively simple components. This also allows for a low weight of the drivetrain.

[0017] The subclaims contain preferred developments of the invention.

[0018] The freewheel preferably comprises a first toothing, in particular spur toothing, on the output shaft, a freewheel element, and a reset device. The freewheel element has a second toothing, in particular spur toothing. The first toothing and the second toothing are designed to effect torque transmission between the output shaft and the freewheel element when they mesh with one another. Furthermore, the freewheel element is arranged so as to be displaceable in the axial direction on the crankshaft and non-rotatable in the circumferential direction relative to the crankshaft. The reset device is designed to move the freewheel element, in particular by means of a restoring force, in the axial direction in such a way as to engage the tooth meshing of the toothings. This makes it possible to provide a simple and cost-effective design which ensures particularly reliable and robust function of the freewheel.

[0019] The return device particularly preferably comprises a spring element which exerts a spring force on the freewheel element in the axial direction with respect to the crankshaft. This means that in particular the spring element holds the two toothings in the engaged position by means of the spring force. Disengagement and thus release of the freewheel can occur, for example, by exerting an opposing force on the freewheel element. This can be achieved, for example, by designing the toothings as sawtooth toothings. In this case, the two toothings slide against one another in the freewheeling direction upon relative rotation of the freewheel element and output shaft, such that the return element is moved away from the output shaft with a force opposite to the spring force. This makes it possible to provide a particularly simple and cost-effective design for the drive arrangement. The freewheel preferably comprises a friction element.A predetermined frictional connection in the circumferential direction is formed between the output shaft and the friction element. In addition, the freewheel element and the friction element are connected to one another by means of a spiral mechanism. The spiral mechanism is designed to bring about a translational displacement of the freewheel element and the friction element relative to one another when the freewheel element and the friction element rotate relative to one another. In other words, a freewheel function is provided by the engagement and disengagement of the gear teeth, in particular spur gear teeth, being implemented via a spiral mechanism actuated by means of a frictional connection. This means that due to the special design of the freewheel element and the friction element, a relative rotation of the crankshaft and the output shaft is converted into a relative rotation of the friction element and the freewheel element via the frictional connection on the friction element.The spiral mechanism causes the freewheel element to be displaced in the axial direction on the crankshaft, and thus in particular to be displaced away from or towards the first toothing, in particular the spur toothing, of the output shaft in order to either disengage or engage the tooth mesh. The spiral mechanism can be designed in a variety of ways. For example, intermeshing helical elements can be provided on the freewheel element and / or friction element. Furthermore, any other intermeshing elements can be arranged on the friction element and freewheel element, for example similar to a slotted guide, which are designed to convert the relative rotation into a relative translational displacement along the axis.The freewheel offers the advantage that a particularly reliable and robust function of the freewheel can be achieved with a particularly simple and cost-effective design, which also has advantageous properties with regard to wear and noise generation. In detail, for example, all elements involved in the function can be designed to be particularly robust mechanically and constructed in such a way that malfunctions can be reliably avoided due to the direct mechanical coupling in all directions of movement or actuation of the freewheel. Since the engagement and disengagement of the gearing is implemented in a particularly targeted and, in particular, forced manner by the spiral mechanism, for example, unwanted slipping of the gearing, for example over a longer period of time, can be prevented. This not only avoids noise but also ensures low wear.In addition, the tooth engagement can be carried out in a particularly robust and reliable manner.

[0020] The turning mechanism preferably comprises a thread. This means that a thread is formed between the freewheel element and the friction element, which performs the corresponding translational displacement function during relative rotation. This allows the desired kinematics of the coupling between the freewheel element and the friction element to be implemented in a particularly simple, cost-effective, and particularly reliable manner. The thread can be designed in various ways, for example, as a standard thread, particularly a metric one, or as any thread with any desired pitch, or the like.

[0021] Particularly preferably, the frictional connection between the output shaft and the friction element comprises a frictional force in the circumferential direction, in particular with respect to the output shaft. This means that the frictional force is oriented tangentially with respect to the output shaft. In particular, the friction element can be designed at least partially as a hollow shaft through which the output shaft extends at least partially. For example, the frictional force can be generated by a radial adhesive force between the friction element and the output shaft. This allows the actuation of the reversing mechanism to be easily and precisely adjusted via the frictional force.

[0022] The friction force is preferably generated by means of at least one screw and / or by means of a friction ring. For example, the at least one screw can be screwed into the friction element and press in the radial direction against the output shaft with a predetermined screw force. The screw force and thus the friction force can thus be generated and adjusted in a particularly simple manner. Several screws distributed around the circumference of the output shaft are particularly advantageous. A friction ring can, for example, be arranged as an additional element between the friction element and the output shaft. For example, the friction force can be formed as a function of surface roughness and / or fits between the friction element and friction ring and / or between the output shaft and friction ring, which also enables a simple and cost-effective design.

[0023] More preferably, the frictional connection between the output shaft and the friction element comprises a magnetic force. This means that the magnetic force between the friction element and the output shaft is provided in such a way that it effects the predetermined frictional connection in the circumferential direction. For example, permanent magnets can be arranged on the friction element and / or the output shaft. This also allows the frictional connection to be achieved in a particularly simple and targeted manner.

[0024] Particularly preferably, the freewheel further comprises a stop that limits the translational displacement of the freewheel element relative to the friction element. In particular, the stop is designed such that it limits displacement of the freewheel element away from the first toothing, in particular the spur toothing. Preferably, when the freewheel element rests against the stop and the output shaft and crankshaft continue to rotate relative to each other, the frictional connection between the output shaft and the friction element is overcome, allowing the output shaft to rotate relative to the friction element. A stop enables a particularly compact and structurally precisely defined design of the freewheel.

[0025] Preferably, the stop is designed such that when the freewheel element rests against the stop, the two toothings, particularly the spur toothings, are completely disengaged from each other. This means that the stop allows such a relative translational displacement of the freewheel element relative to the friction element that, upon reaching the stop, the two toothings no longer touch. This ensures particularly low-wear operation of the freewheel.

[0026] Further preferably, the reversing mechanism is designed such that the meshing of the two gears, in particular spur gears, is disengaged due to the relative translational displacement upon relative rotation of the freewheel element and friction element in the freewheeling direction. Furthermore, the reversing mechanism is designed such that the meshing of the gears is engaged due to the relative translational displacement of the freewheel element and friction element relative to one another upon relative rotation in the locking direction. This means that torque transmission between the crankshaft and output shaft is canceled upon rotation in the freewheeling direction, and enabled upon rotation in the opposite locking direction.

[0027] Preferably, the friction element is fixed axially to the output shaft. In particular, partial areas of the output shaft and the friction element are undercut in the axial direction.

[0028] Preferably, the freewheel element is axially displaceable and fixed to the crankshaft by means of radial toothing, preventing rotation in the circumferential direction. For example, a spline connection between the freewheel element and the crankshaft can be used as the radial toothing. This allows for a simple, robust torque transmission between the freewheel element and the crankshaft while ensuring proper function.

[0029] The spur gears are preferably designed as sawtooth gears or Hirth gears. Sawtooth gears are gears with tooth flanks that are inclined differently relative to an axial direction. One of the two tooth flanks of each tooth can, for example, be arranged parallel to the axial direction. Hirth gears are gears with symmetrical teeth.

[0030] Preferably, the output shaft and the crankshaft are arranged coaxially with each other. Particularly preferably, the output shaft is designed as a hollow shaft through which the crankshaft extends. This enables a particularly simple and compact design of the drive assembly.

[0031] Preferably, the drive arrangement further comprises a motor, preferably an electric motor, which is configured to generate a motor torque to support a driver torque applied by a driver on the output shaft.

[0032] Further preferably, a motor shaft of the engine and the output shaft, and thus preferably also the crankshaft, are arranged parallel to each other and at a predetermined distance from each other. In other words, the motor with the motor shaft is arranged next to the output shaft in the radial direction of the output shaft. This enables a particularly flexible arrangement of the components of the drive arrangement.

[0033] Alternatively, the motor shaft and the output shaft are preferably arranged coaxially with each other. This means that the motor is also preferably arranged coaxially with the output shaft. This allows for a particularly compact geometry of the drive arrangement.

[0034] The drive arrangement preferably comprises two bearings for supporting the output shaft. This means that the output shaft is rotatably mounted by means of the two bearings. The bearing force sensor is arranged in the axial direction of the output shaft at the level of the bearing arranged on the output side. In other words, a drive arrangement is provided which has the bearing force sensor in the region of that of the two bearings which is arranged closer to the output element. The output interface is preferably connected to the output shaft in a rotationally fixed manner. In particular, the output shaft is designed as a single piece. Measuring the bearing force using the bearing force sensor offers the advantage that the output shaft can be designed particularly simply and cost-effectively, while still enabling reliable determination of the forces used, for example, to operate the motor.

[0035] The drive arrangement preferably further comprises a transmission arranged between the motor and the output shaft. The transmission is configured to transmit torque between a motor shaft and the output shaft. The motor shaft is, in particular, an integral component of the motor. In particular, the transmission thus provides a transmission ratio between the motor and the output shaft. The transmission is preferably a spur gear transmission.

[0036] The transmission preferably has an intermediate shaft arranged parallel to the output shaft. This means that, in particular, an intermediate shaft axis of the intermediate shaft is arranged parallel to an output shaft axis of the output shaft. The transmission is designed to transmit torque between the output shaft and the motor shaft via the intermediate shaft. This means that the torque is transmitted from the motor shaft of the motor via the intermediate shaft to the output shaft. This allows the transmission to be provided with a predetermined gear ratio between the output shaft and motor shaft in a particularly simple manner and with few components. In addition, a gear ratio can be easily adjusted, for example, by scaling the intermediate shaft, in particular with corresponding gears.

[0037] The transmission is preferably designed as a spur gear, preferably a two-stage spur gear. This means that two spur gear stages are provided to provide a predetermined gear ratio between the motor shaft and the output shaft. This allows for optimal torque transmission of the drive unit for use in an electric bicycle with a compact design and simple construction. Such a spur gear is characterized by a particularly high level of efficiency, which ensures high efficiency in the operation of the drive assembly.

[0038] Particularly preferably, the transmission comprises a first gear and a second gear. The first gear and the second gear are each connected to the intermediate shaft. For example, the first gear and / or the second gear can be formed together with the intermediate shaft as a single-piece component. Preferably, an additional freewheel, for example, a motor freewheel, can be provided between one of the two gears, preferably the first gear, and the intermediate shaft. This allows for a simple, cost-effective, and robust design.

[0039] The gear unit preferably has motor gearing formed on the motor shaft. In particular, a portion of the motor shaft is thus designed as a gear with the motor gearing. The first gear meshes with the motor gearing. This further advantageously facilitates a compact, simple, and cost-effective design.

[0040] Further preferably, the transmission comprises a third gear that can be connected to the output shaft in a rotationally fixed manner. The third gear meshes with the second gear of the intermediate shaft. In particular, the torque can thus be transmitted from the intermediate shaft to the output shaft via the third gear.

[0041] Particularly preferably, the motor is arranged on a side of the transmission facing the output interface. This means that the motor is arranged closer to the output element than the transmission in the axial direction of the output shaft. Alternatively, the motor is preferably arranged on a side of the transmission facing away from the output interface. This means that in this case, the transmission is arranged closer to the output interface than the motor. In other words, the motor can be arranged on the right or left with respect to a direction of travel of the vehicle, on which the drive arrangement can be arranged.

[0042] Particularly preferably, the drive unit further comprises a further freewheel between the motor shaft and the output shaft. Particularly preferably, the further freewheel is arranged between the motor shaft and the output shaft, in particular between the intermediate shaft and the first gear, or alternatively the second gear. In particular, the further freewheel is designed to be able to switch between a rotationally fixed connection and a relatively freely rotatable connection between the motor shaft and the output shaft. Preferably, the further freewheel locks in the drive direction of the motor and opens when the motor is at a standstill and during actuation of the cranks. Alternatively or additionally, the further freewheel can be designed to be controllably actuated, for example by means of a control unit.In particular, the additional freewheel can be used to decouple the motor from the rest of the drive train, for example, to deactivate the motor assistance, especially when a predetermined vehicle speed is exceeded. This means that the additional freewheel acts as a motor freewheel.

[0043] Particularly preferably, the drive arrangement further comprises a bearing receptacle which at least partially surrounds the bearing in a ring shape. In particular, the bearing receptacle surrounds the bearing essentially completely, preferably except for a predetermined gap area. The bearing receptacle is particularly designed to hold the bearing. For example, the bearing receptacle can be designed as a bearing shell. A bending beam which can be bent in the radial direction is preferably formed on the bearing receptacle, wherein at least one of the two bearing force sensors is arranged on the bending beam. In particular, the bearing force sensor thus detects a force on the bending beam which can arise based on a deformation of the bending beam caused by the bearing force. The use of the bending beam can thereby provide a particularly sensitive structure.In particular, since one end of the bending beam is designed to be freely movable, even small bearing forces can lead to deformation of the bending beam, making the forces easy and precise to measure. This allows for very precise measurement of small bearing forces. In applications such as electric bicycles, this offers the advantage that small torque values ​​can be measured precisely and sensitively, enabling, for example, particularly precise control of the motor drive unit based on the rider's torque.

[0044] Preferably, a portion of the bearing support is designed as a radially bendable beam. This means that the beam is an integral part of the bearing support itself. This allows for a particularly simple design of the drive assembly.

[0045] The bearing mount preferably has a slot, in particular a radial one. The bending beam is adjacent to the slot. In other words, the bending beam is formed through a portion of the bearing mount such that the bearing mount is slotted, with a freely movable end adjacent to the slot corresponding to a freely movable end of the bending beam. This allows for a particularly simple and cost-effective construction that enables the advantageous properties of the sensitive bending beam.

[0046] Particularly preferably, the bearing mount has two bending beams and one bearing force sensor per bending beam. The two bending beams are preferably designed symmetrically with respect to the slot and preferably have identical geometric properties. This enables particularly precise detection of the bearing force. For a particularly simple and cost-effective design, the two bearing force sensors can preferably be identical in construction. The two bearing force sensors are preferably arranged aligned in different directions in order to be able to detect bearing forces in different directions. Each of the two bearing force sensors is preferably designed and arranged to detect a force in the radial direction with respect to the output shaft.This allows for a particularly simple and space-saving arrangement to be provided, which also enables a reliable determination of a bearing force direction and a bearing force magnitude of the total resulting bearing force.

[0047] The arrangement preferably further comprises a stop that limits movement of the bending beam in the radial direction. In particular, the stop limits the maximum deflection in the radial direction of a free end of the bending beam. This makes it possible to provide a particularly high level of mechanical robustness of the arrangement using a simple and cost-effective design. In particular, the stop can limit the deformability of the bending beam to a maximum extent. This can prevent, for example, damage to the bearing mount. In addition, robust and reliably precise positioning of the bearing by means of the bearing mount is ensured. Furthermore, the stop offers the advantage that the bending beam can be optimally designed for clear and easily detectable deformability in a specific bearing force range.For example, for particularly sensitive detection, the bending beam can be designed to be slightly deformable at low bearing forces, with the stop preventing excessive deformation.

[0048] Further preferably, the stop is arranged such that, in the unloaded state of the bearing, a predetermined air gap is formed between a free end of the bending beam and the stop. Preferably, the air gap in the unloaded state is a maximum of 0.1 mm. The air gap thus ensures free deformability of the bending beam until the stop is reached, so that the bearing force can be detected particularly precisely based on this. The air gap can be adjusted particularly easily, for example during assembly of the arrangement by appropriately aligning the stop. The drive arrangement preferably comprises a housing. The bearing receptacle has a fastening region which is fixed to the housing, in particular immovably. The housing can be a motor housing, for example.By fixing the bearing support to the housing, a precise, and particularly immovable, mounting of the bearing relative to the housing is provided. The fastening area can, for example, be a section of the bearing support that corresponds, along the circumferential direction, to at least one-third, preferably at least half, and preferably at most three-quarters, of the entire ring of the bearing support.

[0049] Preferably, the fastening region is formed as at least part of an outer circumference of the bearing receptacle. This means that, in particular, the bearing receptacle is fixed to the housing in that the outer circumference of the bearing receptacle is at least partially fixed directly to the housing, preferably by means of a press connection between the outer circumference and the housing. This makes it possible to provide a particularly simple, lightweight, and cost-effective design of the arrangement. In addition, a particularly high positional accuracy of the bearing receptacle and thus of the bearing can be provided because, for example, the recess in the housing can be manufactured in a simple and cost-effective manner with high precision. This is particularly advantageous if the housing is a deep-drawn component, preferably a sheet metal housing in which the recess is produced by deep-drawing.

[0050] The bearing receptacle is preferably arranged in a recess in the housing. A radially outer dimension of the free end of the bending beam is smaller than an inner dimension of the recess in the housing by a predetermined gap. In other words, the radially outer dimension of the free end of the bending beam is set back by the predetermined gap relative to the preferably circular outer contour of the fastening element. The gap is preferably a maximum of 0.1 mm, in particular at least 0.01 mm. As a result, the housing forms a stop for the bending beam, in particular without a separate component being required for the stop. This makes it possible to provide a particularly simple and cost-effective construction with few components. A stop region is preferably provided at the free end of the bending beam, with the gap being provided between the stop region and the housing.The gap dimension is therefore considered to be, in particular, a free gap between the, for example, radius-shaped, tip of the bending beam and the inner circumference of the housing recess. As the force increases, the bending beam bridges the gap and comes into contact with the inner circumference of the recess. Preferably, there is an axial distance between the remaining area of ​​the bending beam and the recess that is greater than the gap dimension, so that, in particular, free movement of the bending beam is possible, and the bending beam only contacts the stop area.

[0051] The bearing receptacle preferably has a holding region. At least a partial region of the holding region and an edge of the recess in the housing are designed such that the partial region of the holding region and the edge of the recess undercut each other in the radial direction. The holding region is also arranged on a side of the bearing receptacle facing away from the free end of the bending beam. In other words, the bearing receptacle is designed such that the free end of the bending beam and the holding region are arranged on opposite sides of the bearing receptacle. The holding region rests on the housing in such a way that the position of the bearing receptacle, in particular along a direction that extends, for example, from the free end to the holding region, is held in a precisely defined manner relative to the bearing.This ensures that the predetermined gap between the inner dimension of the recess and the free end of the bending beam is precisely maintained. Furthermore, the gap can be reliably maintained with tight tolerances during production in a simple and cost-effective manner. The holding area can, for example, have an area that protrudes at least radially outward from an annular base area of ​​the bearing support and an area that protrudes tangentially from this area.

[0052] Particularly preferably, the holding region is annular and is essentially in complete contact with the edge of the recess. In particular, the entire bearing receptacle thus has two annular partial regions which are arranged next to one another in the radial direction and are connected to one another at a connection point to form a one-piece component. For example, the bearing receptacle can thus be designed in the shape of an "8". In particular, the connection point forms a narrowing of the outer circumference of the bearing receptacle, whereby the undercut with the housing can be provided in order to enable the precisely defined relative arrangement. In this way, an optimal positional tolerance can be provided with particularly simple and cost-effective design and manufacturability.

[0053] Preferably, the holding area is designed as a bearing seat for another bearing. In other words, the holding area is designed to accommodate another bearing, such as a bearing of an intermediate shaft. This allows multiple functions to be fulfilled simultaneously in a simple and cost-effective manner using a small number of components.

[0054] The bearing force sensor preferably has a strain gauge. For example, by attaching a strain gauge to the bending beam, its deformation can be measured particularly easily. The strain gauge can be used to determine, for example, strain and / or compression, and based on this, the deformation, and also, for example, a mechanical force on the bending beam.

[0055] Alternatively or additionally, the bearing force sensor preferably comprises a piezo element. This allows, similar to a strain gauge, a deformation and / or a momentarily acting force on the bending beam to be determined in a particularly simple, space-saving, and cost-effective manner.

[0056] Alternatively or additionally, the bearing force sensor preferably comprises a magnetic sensor. For example, the magnetic sensor can be a Hall sensor, in particular by means of which a relative position change of a partial area of ​​the bending beam relative to another component, such as the housing, can be directly detected in a simple and particularly precise manner.

[0057] Preferably, the drive arrangement further comprises a crank mechanism with cranks. The cranks are connected, in particular in a rotationally fixed manner, to the crankshaft or fixed to the crankshaft. Using the cranks, the rider can apply a pedaling force using muscle power, which creates a pedaling torque on the crankshaft.

[0058] Furthermore, the invention leads to a vehicle that can be operated with muscle power and / or motor power, in particular an electric bicycle, which comprises the drive arrangement described.

[0059] Furthermore, the invention relates to a method for operating the drive arrangement described above. The method comprises the following steps:

[0060] - Determination of forces using the two bearing force sensors, and

[0061] - Determining a bearing force on the bearing based on the forces detected by the bearing force sensors. This method is characterized by its particularly simple and cost-effective implementation, allowing precise results for the bearing force on the bearing to be determined.

[0062] The method preferably further comprises the step of determining an output force on the output element based on, in particular, the bearing force direction and the bearing force magnitude. The output force is considered to be a force exerted by a transmission element, such as a bicycle chain, on the output element, in particular during operation of the electric bicycle. The output force is preferably present on an outer circumference of the chainring and in a predetermined direction along which the bicycle chain extends, for example, to a rear wheel. The output force is preferably additionally determined based on previously known geometric properties of the drive arrangement, in particular of the chainring.

[0063] The method further preferably comprises the step of determining the rider torque applied by the rider based on the determined output force and the motor torque, in particular when an electric bicycle comprising the drive arrangement is operated simultaneously using muscle power and motor power. In particular, the motor torque is known in advance based on a motor control system. The rider torque is preferably determined by determining a rider force, wherein the rider force corresponds to a portion of the output force generated by the rider's muscle power. In particular, a relationship between rider torque and rider force is defined by the known geometric properties of the drive arrangement, in particular of the chainring.Rider force is preferably determined by subtracting the motor force from the total output force, where the motor force corresponds to the force acting on the bicycle chain resulting from the motor torque. This allows the rider torque to be determined particularly simply and precisely.

[0064] Preferably, the method further comprises the step of controlling a motor torque generated by the motor as a function of the bearing force direction and the bearing force magnitude. Particularly preferably, the motor is controlled as a function of the determined rider torque. This means that a motor torque is provided to assist the rider's pedaling force as a function of the bearing force, or rather, the rider torque, which is determined based on the determined bearing force.

[0065] Preferably, the bearing force direction and the bearing force magnitude are determined based on a calibration of the drive assembly. Calibration is performed by determining a ratio of the respective forces detected by the bearing force sensors during actuation of the crank mechanism in a predetermined calibration configuration. In the calibration configuration, the crank mechanism is actuated with an actuation force in a predetermined actuation direction. Calibration is particularly preferably performed by detecting multiple ratios in several different predetermined actuation directions. Calibration is preferably performed once with the drive assembly mounted on an electric bicycle.

[0066] Short description of the drawings

[0067] The invention is described below using an exemplary embodiment in conjunction with the figures. In the figures, functionally identical components are identified by the same reference numerals. Figure 1 shows a simplified schematic view of an electric bicycle with a drive arrangement according to a first exemplary embodiment of the invention.

[0068] Figure 2 is a sectional view of the drive arrangement of Figure 1,

[0069] Figure 3 is a detailed sectional view of the drive arrangement of Figure 1,

[0070] Figure 4 is a sectional view of a drive arrangement according to a second embodiment of the invention,

[0071] Figure 5 is a detailed sectional view of the drive arrangement of Figure 4,

[0072] Figure 6 is a simplified detailed sectional view of the drive arrangement of Figure 1 to illustrate the operation of a bearing force detection system, and

[0073] Figure 7 is a perspective detailed view of the drive arrangement of Figure 1.

[0074] Preferred embodiments of the invention

[0075] Figure 1 shows a simplified schematic view of an electric bicycle 100 with a drive assembly 1 according to a first embodiment of the invention. The drive assembly 1 is shown in sectional views in Figures 2 and 3. Details of the drive assembly 1 of the first embodiment are further shown in Figures 6 and 7.

[0076] The drive assembly 1 comprises a crank mechanism 2 with two cranks 21 located opposite one another with respect to a pedal axis 22a. Pedals 25 are arranged on the cranks 21, via which a rider can generate a rider torque on the drive assembly 1 using muscle power.

[0077] In addition, the drive assembly 1 comprises a crankshaft 22d, which is non-rotatably connected to the cranks 21, and an output shaft 22, which has an output interface 35. An output element 3, which is a chainring, is non-rotatably connected to the output interface 35. A bicycle chain 107, as a transmission element, engages the chainring 3 (see Figure 1).

[0078] The output shaft 22 and the crankshaft 22d are arranged coaxially to each other, wherein the output shaft 22 is designed as a hollow shaft, and wherein the crankshaft 22d protrudes through the output shaft 22 (see Figure 2).

[0079] Furthermore, the drive arrangement 1 comprises two bearings 23, 24 for rotatably supporting the arrangement of crankshaft 22d and output shaft 22.

[0080] To support the driver torque with an additional engine torque, the drive arrangement 1 comprises a motor 4, preferably an electric motor, which is supplied with electrical energy in particular by an electrical energy storage device (not shown) and which is designed to generate the engine torque.

[0081] The drive assembly 1 is preferably attached to a bicycle frame 101 of the electric bicycle 100 by means of a housing 40.

[0082] The output shaft 22 is mounted in the housing 40 by means of the two bearings 23, 24. The housing 40 has a bearing collar 43 on the bearing 23 facing away from the output shaft, within which the bearing 23 is arranged (see Figure 2). In particular, the bearing collar 43 is an integral part of the housing 40.

[0083] In addition, the drive arrangement 1 comprises a transmission 8. The transmission 8 is designed to transmit torque between a motor shaft 42 of the motor 4 and the output shaft 22.

[0084] The gear 8 is arranged along the direction of the pedal axis 22a between the motor 4 and the output interface 35. With respect to a direction of travel A (see Figures 1 and 2), the output interface 35 is thus located on the right side of the output shaft 22 and the motor 4 on the left side. In other words, apart from the left crank, the motor 4 is the leftmost element of the drive assembly 1. The gear 8 is a two-stage spur gear. This means that the gear 8 comprises several gears designed as spur gears that mesh with each other to transmit torque. Their arrangement is described in more detail below.

[0085] In the drive arrangement 1, the motor shaft 42 of the motor 4 and the output shaft 22 are arranged parallel to each other and at a distance from each other.

[0086] In an alternative preferred embodiment (not shown), a coaxial arrangement of the motor and output shaft can also be provided. In this case, the motor shaft and the output shaft are preferably arranged coaxially with each other, whereby the motor shaft can be designed, for example, as a hollow shaft through which the crankshaft extends.

[0087] The motor shaft 42 of the motor 4 protrudes in the axial direction beyond the rotor of the motor 4. A motor toothing 84 is formed on this projecting portion of the motor shaft 42.

[0088] The motor gearing 84 engages with a first gear 81 of the transmission 8. The first gear 81 is connected to an intermediate shaft 85 of the transmission 8 via a freewheel 89, which is designed as a motor freewheel. The intermediate shaft 85 extends along an intermediate shaft axis 80 and is arranged to be freely rotatable about this intermediate shaft axis 80.

[0089] In addition, the transmission 8 includes a second gear 82, which is also rotationally fixedly connected to the intermediate shaft 85. Preferably, the second gear 82 and the intermediate shaft 85 can be formed together as a single, integral component, or alternatively as separate, interconnected components.

[0090] In addition, the transmission 8 includes a third gear 83, which is arranged to rotate about the pedal axis 22a. The third gear 83 is formed as a single-piece component together with the output shaft 22. A freewheel 6 is located between the output shaft 22 and the crankshaft 22b, which enables either a rotationally fixed connection or a freely rotatable arrangement of the output shaft 22 and the crankshaft 22d relative to one another. The freewheel 6 is described in detail below.

[0091] The freewheel 6 comprises a first axial spur gear 61, which is formed as an integral part of the output shaft 22. Furthermore, the freewheel 6 comprises a freewheel element 63, which has a second axial spur gear 62.

[0092] The freewheel element 63 is disc-shaped and arranged on an outer circumference of the crankshaft 22d. A radial toothing 68 is formed between the freewheel element 63 and the crankshaft 22d, such that the freewheel element 63 is displaceable in the axial direction on the crankshaft 22d and is arranged non-rotatably relative to the crankshaft 22d in the circumferential direction. This allows torque to be transmitted between the crankshaft 22d and the freewheel element 63.

[0093] In addition, the freewheel 6 comprises a return device 64, which comprises a spring element 64a, in particular in the form of a compression spring. The spring element 64a exerts a spring force 64b in the axial direction on the freewheel element 63, so that the second spur gear 62 of the freewheel element 63 is pressed toward the first spur gear 61 to engage these two spur gears 61, 62, as indicated by arrow B in Figure 3.

[0094] The two spur gear teeth 61, 62 are designed as sawtooth gear teeth, which, when the crankshaft 22d rotates in the forward direction of rotation E and in the engaged state, create a rotationally fixed connection between the crankshaft 22d and the output shaft 22, thus transmitting torque. When the crankshaft 22d rotates in the opposite reverse direction of rotation D relative to the output shaft 22, the sawtooth gear teeth cause the respective teeth of the spur gear teeth 61, 62 to slide against each other, so that no torque is transmitted, i.e., the freewheel 6 opens.

[0095] In particular, this sliding of the teeth displaces the freewheel element 63 in the direction of arrow C, so that the spur gears 61, 62 are disengaged. The freewheel 6 thus acts as a driver's freewheel, which can decouple the crank drive from the output shaft 22.

[0096] During motor-assisted operation of the electric bicycle 100, the motor torque is further adjusted depending on the rider torque applied by the rider. The rider torque is determined by determining a bearing force 59 on the output-side bearing 24, as described below.

[0097] To determine the rider torque based on the bearing force 59, several known mechanical and geometric relationships as well as the motor torque known from the operation of the motor 4 are used. In detail, the relationship used is that an output force 60 relevant for the propulsion of the electric bicycle 100 on the chainring 3 (see Figure 6) causes a reaction force of the same magnitude and parallel to it in the opposite direction on the output-side bearing 24.

[0098] With knowledge of the geometry and mechanics of the crank mechanism 2 and the engine torque of the engine 4, a portion of the output force 60 generated by the engine 4, i.e., a motor force, can be determined. By subtracting the motor force from the total output force 60, the driver force, which corresponds to the portion of the output force 60 generated by the driver's muscle power, can be easily determined. The corresponding driver torque can then also be easily determined using the geometric properties of the drive arrangement 1.

[0099] In the present drive assembly 1, the bearing force 59 is determined using a simple, compact, and cost-effective design, which also allows for particularly sensitive and precise detection. For this purpose, the drive assembly 1 has two bearing force sensors 51, 52, which are arranged in the region of the output-side bearing 24. The arrangement of the two bearing force sensors 51, 52 is shown in Figures 6 and 7. Both bearing force sensors 51, 52 are located in the axial direction of the output shaft 22 at the level of the output-side bearing 24.

[0100] Each of the two bearing force sensors 51, 52 is designed as a strain gauge and is configured to detect a force 55, 56 resulting, for example, from a mechanical extension and / or compression along exactly one predetermined direction, namely in the radial direction with respect to the pedal axis 22a.

[0101] The two bearing force sensors 51, 52 are connected to a detection unit 54, which determines the respective forces 55, 56 and also determines all other forces and moments.

[0102] The bearing force sensors 51, 52 are arranged on a radially outer side of a bearing support 5. The bearing support 5 is a component formed separately from the housing 40 of the motor 4 and is designed, in particular, as a bearing shell. In the first exemplary embodiment, the bearing support 5 has a substantially figure-8 geometry.

[0103] Figure 7 shows a detailed view of the drive assembly with the bearing support 5. The bearing 24 is arranged in a recess of the bearing support 5, wherein, in the unloaded state, preferably substantially the entire inner circumference of the bearing support 5 is in contact with an outer circumference of the bearing 24. The bearing support 5 is arranged in a recess 65 of the housing 4.

[0104] The bearing holder 5 is also slotted, with a slot 57 which extends completely through the entire bearing holder 5 in the radial direction.

[0105] The bearing mount 5 additionally has a retaining region 54c, which is annular. The retaining region 54c and the likewise annular base region of the bearing mount 5, which forms the bearing seat for the bearing 24, together form a one-piece component, which is essentially shaped like an "8." The retaining region 54c has a further recess 54b, which is designed in particular as a circular through-opening. The recess 54b is coaxial with the intermediate shaft axis 80 (see Figure 2). A bearing 60a for supporting the intermediate shaft 85 can be arranged in the recess 54b.

[0106] Housing 40 and bearing receptacle 5 are designed such that an inner edge 65b of the recess 65 of the housing 40 is essentially completely in contact with the outer circumference of the holding area 54c, in particular by means of a press connection.

[0107] Due to the "8-shaped" geometry of the bearing support 5 and the recess 65 of the housing 40, an undercut is formed in a plane perpendicular to the pedal axis 22a and along a direction 22e that corresponds to a straight line connecting the two axes 22a, 22b. The undercut is identified in Figure 7 by reference numeral 54a.

[0108] This ensures precise, unambiguous fixation of the bearing support 5 in the housing 40 by the outer circumference of the bearing support 5 and the inner edge 65b of the recess 65. In particular, the outer circumference of the bearing support 5 in the third embodiment forms the fastening area 50 for fixing the bearing support 5 to the housing 40.

[0109] Due to the special geometry with the undercut 54a along the direction 22e, a precisely defined relative position of the bearing support 5 and the housing 40 is achieved in a particularly simple and cost-effective manner with few components.

[0110] In addition, the bearing receptacle 5 has two bending beams 53, each arranged between the slot 57 and the fastening area 50. The bending beams 53 are designed such that they can deform in the radial direction. On the radially outer side of each bending beam 53 there is a flattened area on which the respective bearing force sensor 51, 52 is arranged. The bearing receptacle 5 is designed and arranged in the recess 65 of the housing 40 such that a radially outer dimension 53b of the free end 53a of the bending beam 53 is smaller than an inner dimension 65a of the recess 65 by a predetermined gap dimension 53c (cf. Figure 7). This causes the inner circumference of the recess 65 to act as a stop 7. This means that if one of the bending beams 53 is deformed radially outward by the bearing force 59, this deformation is limited by the free end 53a of the bending beam 53 resting on the inner circumference of the recess 65.This allows for a particularly simple and lightweight design of the drive assembly 1. Furthermore, it is particularly easy and cost-effective to manufacture.

[0111] If the crank mechanism 2 is loaded by the rider's pedaling force, this causes a bearing force 59 on the bearing 24. Since the bearing 24 is held in the housing 40 of the motor 4 by the bearing support 5, this bearing force 59 has a corresponding effect on the bearing support 5. Due to the special design of the bearing support 5 with the movable bending beams 53, the bearing force 59 leads to a deflection of the bending beams 53 in the radial direction. This deformation can be detected by the bearing force sensors 51, 52, which are designed as strain gauges.

[0112] Based on the above-described known geometric and mechanical properties of the drive arrangement 1, the total resulting bearing force 59, namely the bearing force direction and the bearing force magnitude, can be determined based on the detected deformations.

[0113] The free movement of the bending beams 53 in the radial direction enables particularly sensitive detection with appropriate mechanical design. This means, for example, by appropriately designing the thicknesses of the bending beams 53 in the axial and / or radial direction, it is possible for a clearly measurable deformation to occur even with small bearing forces. In particular, this enables the detection of low torques applied by the driver with high accuracy. To ensure particularly high accuracy by ensuring the deformation of the bending beams 53 is as unaffected as possible, the bending beams 53 are slightly spaced apart from a housing wall of the housing 40 in the axial direction. As a result, the deformation of the bending beam 53 is not influenced by friction, for example.

[0114] Furthermore, the bending beams 53 and / or the bearing 24 can be designed such that a region with the lowest possible friction is formed between the radially inner side of the bending beams 53 and the radially outer side of the bearing 24, so that, for example, a falsification of the measurement results due to stresses caused by static friction can be avoided or reduced.

[0115] In order to be able to determine the output force 60 acting on the bicycle chain 107, and thus also the rider torque as described above, based on the determined bearing force 59, it is necessary to know the relative orientation of the chain direction 70 of the bicycle chain 107 and the motor 4 to one another, i.e. the installation position of the motor 4 on the bicycle frame 101.

[0116] In order to correctly determine the output force 60 based on the bearing force 59, knowledge of the geometric relationship between motor 4 and chain device 70 is necessary.

[0117] For this purpose, a one-time calibration of the drive assembly 1 is performed. During the calibration, no motor torque is generated by the motor 4.

[0118] During calibration, in a first step, the crank drive 2 can be arranged so that the cranks 21 are aligned horizontally. In this first calibration configuration, exactly one crank 21, namely the crank 21 pointing forward in the direction of travel, is actuated with an actuating force. The actuating force is aligned vertically, i.e. orthogonal to the crank 21, and is applied by actuating the pedal. As a result, the entire actuating force is transferred to the bicycle chain 107. A corresponding bearing force 59 corresponds to a resultant force from the actuating force and the output force 60. In a second step of calibration, the crank drive 2 can be arranged so that the cranks 21 are aligned vertically. In this second calibration configuration, the lower crank 21 is actuated with an actuating force that is also aligned vertically, i.e. parallel to the crank 21.In this second actuation configuration, the output force 60 can be zero due to the corresponding orientation of the crank mechanism 2. However, the actuation force still generates a bearing force 59.

[0119] Based on the forces 55, 56 of the bearing force sensors 51, 52 recorded in both calibration steps, the ratio of the two forces 55, 56 can be used to determine the orientation of the bearing force sensors 51, 52 relative to the previously known positions of the cranks 21 and / or the bicycle chain 107. This also allows the orientation of the motor 4 relative to the bicycle chain 107 to be determined. The orientation thus determined can then be used as the basis for determining the driver torque based on the bearing force direction and the bearing force magnitude of the bearing force 59.

[0120] By combining the special bearing force detection with the parallel arrangement of motor 4 and motor shaft 42 next to the output shaft 22 and with the design of the arrangement of the freewheel 6 between the crankshaft 22d and the output shaft 22, a particularly advantageous compact geometry of the drive arrangement 1 can be provided.

[0121] Figure 4 shows a sectional view of a drive assembly 1 according to a second embodiment of the invention. Figure 5 shows a detailed view of the drive assembly of Figure 4. The second embodiment essentially corresponds to the first embodiment, with the difference of an alternative design of the freewheel 6.

[0122] In the second exemplary embodiment, the freewheel 6 comprises a return device 64 with a friction element 66, which is arranged essentially coaxially with the crankshaft 2 and the output shaft 3. Similar to the first exemplary embodiment, the freewheel element 6 can cause the engagement and disengagement of the axial spur gear teeth 61, 62 by translational displacement along the crankshaft axis 22a in order to enable or interrupt the torque transmission between the output shaft 22 and the crankshaft 22d. The translational displacement of the freewheel element 63 (arrows B and C in Figure 5) is effected as a function of a relative rotation of the crankshaft 22d and the output shaft 22 in a specific rotational direction and by the friction element 66, as described below.

[0123] The friction element 66 is designed as a hollow shaft or essentially sleeve-shaped and arranged radially outside the freewheel element 63. The friction element 66 is axially immovably attached to the output shaft 22, specifically to the third gear 83, allowing relative rotation between the friction element 66 and the third gear 83. A predetermined frictional connection in the circumferential direction is formed in the form of a frictional connection between the friction element 66 and the third gear 83, which causes the friction element 66 to rotate with the third gear 83 and thus with the output shaft 22 if the frictional connection is not overcome.

[0124] The freewheel 1 also comprises a spiral mechanism 67, which is formed between the freewheel element 63 and the friction element 66. In the second exemplary embodiment, the spiral mechanism 67 comprises a thread between a radially inner side of the friction element 66 and a radially outer side of the freewheel element 63. The thread of the spiral mechanism 67 is designed such that, upon relative rotation of the crankshaft 22 in the locking direction E, it causes the engagement of the teeth, i.e., the meshing of the two spur gears 61, 62, by moving the freewheel element 63 in the direction of arrow B (see Figure 5). Upon relative rotation of the crankshaft 22d in the opposite freewheel direction D, the disengagement of the teeth, i.e., the release of the meshing of the two spur gears 61, 62, is effected by moving the freewheel element 63 in the direction of arrow C.

[0125] The freewheel 6 also includes a stop 69 that limits the axial displacement of the freewheel element 63 relative to the crankshaft 22d. For this purpose, the stop 69 includes a retaining ring arranged in a groove on a radially inner side of the third gear 83.

[0126] When the freewheel element 63 is displaced far enough that the stop 69 is reached, the frictional connection between the friction element 66 and the third gear 83 is overcome upon further relative rotation of the crankshaft 2 in the freewheel direction D, so that the friction element 66 and the third gear 83, and thus also the output shaft 22, can rotate relative to one another. The second embodiment thus offers an alternative freewheel 6 which, in addition to a particularly simple and robust construction, allows reliable operation, in particular without noise generation, since the forced actuation of the freewheel 6 via the reversing mechanism 67 enables complete and targeted disengagement and engagement of the spur gears 61, 62.

Claims

Claims 1 . Drive arrangement of a vehicle (100) operable with muscle power and / or motor power, in particular an electric bicycle, comprising: - a crankshaft (22d) which is designed for rotationally fixed connection with cranks (21) of a crank drive (2), - an output shaft (22) with an output interface (35) which is designed to be connected to an output element (3), - a freewheel (6) between the output shaft (22) and the crankshaft (22d), - at least one bearing (24) by means of which the output shaft (23) is mounted, - at least one bearing force sensor (51, 52), in particular two bearing force sensors (51, 52), - wherein the bearing force sensor (51, 52) is arranged to detect a force (55, 56), and - a detection unit (54) which is configured to detect a bearing force (59) on the bearing (24) based on the force (55, 56) detected by the bearing force sensor (51, 52).

2. Drive arrangement according to claim 1, wherein the two bearing force sensors (51, 52) are arranged at different circumferential positions relative to the output shaft (22).

3. Drive arrangement according to one of the preceding claims, wherein the freewheel (6) comprises: - a first toothing (61) on the output shaft (22), - a freewheel element (63) having a second toothing (62), and - a reset device (64), - wherein the first toothing (61) and the second toothing (61) are arranged to effect a torque transmission between the output shaft (22) and the freewheel element (63) when engaged with each other, - wherein the freewheel element (63) is arranged on the crankshaft (22d) so as to be displaceable in the axial direction, - wherein the freewheel element (63) is arranged non-rotatably in the circumferential direction relative to the crankshaft (22d), and - wherein the return device (64) is arranged to move the freewheel element (63) in the axial direction in such a way as to engage the tooth engagement of the two toothings (61, 62).

4. Drive arrangement according to claim 3, wherein the return device (64) comprises a spring element (64a) which exerts a spring force (64b) in the axial direction on the freewheel element (63).

5. Drive arrangement according to claim 3, - wherein the return device (64) comprises a friction element (66), - wherein a predetermined frictional connection is formed in the circumferential direction between the output shaft (22) and the friction element (66), and - wherein the freewheel element (63) and the friction element (66) are connected to one another by means of a turning mechanism (67) which is designed to cause a translational displacement of the freewheel element (63) and the friction element (66) relative to one another upon relative rotation of the freewheel element (63) and the friction element (66).

6. Freewheel according to claim 5, wherein the reversing mechanism (67) is designed such that the corresponding relative translational displacement disengages the tooth engagement of the toothings (61, 62) during a relative rotation in the freewheeling direction, and engages the tooth engagement of the toothings (61, 62) during a relative rotation in the locking direction.

7. Drive arrangement according to one of the preceding claims, wherein the output shaft (22) and crankshaft (22d) are arranged coaxially to one another.

8. Drive arrangement according to one of the preceding claims, further comprising a motor (4) which is arranged to generate a motor torque to support a driver torque applied by a driver on the output shaft (22), wherein a motor shaft (42) of the motor (4) and the output shaft (22) are arranged parallel to each other and at a predetermined distance from each other.

9. Drive arrangement according to one of the preceding claims, comprising two bearings (23, 24) for supporting the output shaft (22), wherein the bearing force sensor (51) is arranged in the axial direction of the output shaft (22) at the level of the bearing (24) arranged on the output side.

10. Drive arrangement according to one of the preceding claims, further comprising a gear (8) which is arranged between the motor (4) and the output shaft (22) and configured to transmit torque between the motor shaft (42) and the output shaft (22) via an intermediate shaft (85), in particular wherein the gear (8) is designed as a, preferably two-stage, spur gear.

11. Drive arrangement according to claim 10, - wherein the transmission (8) comprises a first gear (81) and a second gear (82), wherein the first gear (81) and the second gear (82) are connected to the intermediate shaft (85), - wherein the gear (8) has a motor toothing (84) formed on the motor shaft (42), and wherein the first gear (81) is in engagement with the motor toothing (84), - wherein the transmission (8) has a third gear (83) which is rotatably connectable to the output shaft (82), and wherein the third gear (83) is in engagement with the second gear (82).

12. Drive arrangement according to one of the preceding claims, further comprising a further freewheel (89) between the motor shaft (42) and the output shaft (22).

13. Drive arrangement according to one of the preceding claims, further comprising a bearing receptacle (5) which at least partially surrounds the bearing (24) in a ring shape, wherein a bending beam (53) which can be bent in the radial direction is formed on the bearing receptacle (5), wherein at least one of the bearing force sensors (51, 52) is arranged on the bending beam (53).

14. Drive arrangement according to claim 13, wherein a partial region of the bearing holder (5) is designed as the bending beam (53) bendable in the radial direction, and wherein the bearing holder (5) has a, in particular radial, slot (57), and wherein the bending beam (53) adjoins the slot (57).

15. Drive arrangement according to one of claims 13 or 14, wherein the bearing holder (5) has two bending beams (53), and wherein one of the two bearing force sensors (51, 52) is arranged on each bending beam (53).

16. Drive arrangement according to one of claims 13 to 15, further comprising a stop (7) which limits a movement of the bending beam (53) in the radial direction, in particular wherein the stop (7) is arranged such that in the unloaded state of the bearing (24) a predetermined air gap (70) is arranged between a free end (53a) of the bending beam (53) and the stop (7).

17. Drive arrangement according to one of the preceding claims, wherein the bearing force sensor (51) comprises a strain gauge and / or a piezo element and / or a magnetic sensor.

18. A vehicle operable by muscle power and / or motor power, comprising a drive arrangement (1) according to one of the preceding claims.

19. A method for operating a drive arrangement (1) according to one of claims 1 to 17, comprising the steps: - Determining forces (55, 56) by means of the at least one bearing force sensor (51, 52), in particular the two bearing force sensors (51, 52), and - Determining a bearing force (59) on the bearing (24) based on the force (55, 56) detected by the bearing force sensor (51, 52).

20. The method of claim 19, further comprising the steps of: - determining an output force (60) on the output element (3) based on the determined bearing force (59), and - Determining the driver torque applied by the driver based on the output force (60) and an engine torque of the engine (4).

21. The method according to any one of claims 19 or 20, further comprising the step: - Controlling a motor torque generated by the motor (4) as a function of the determined bearing force (59).

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