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

Abstract

The invention relates to a drive assembly of a vehicle (100) which can be driven by muscle power and / or motor power, in particular an electric bicycle, comprising a crank drive (2) with a crankset (27), a bottom bracket axle (22), and two bottom brackets (23, 24) for supporting the bottom bracket axle (22), wherein the crankset (27) has a crank (21) and an output element (3) which is rotationally fixed to the crank (21); at least one bracket force sensor (51, 52), in particular two bracket force sensors (51, 52), said bracket force sensor (51, 52) being designed to detect a force (55, 56); and a detection unit (6) which is designed to detect a bracket force on at least one bottom bracket (24) on the basis of the force (55, 56) detected by the bracket 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 10 2010 001 775 A1.

[0007] Disclosure of the invention

[0008] The drive arrangement according to the invention with the features of claim 1 is distinguished in that a bearing force at a bottom bracket of a vehicle operable with muscle power and / or motor power can be precisely determined in a particularly simple and cost-effective manner. This also enables, for example, a particularly simple and cost-effective design of the drive arrangement, preferably with the use of standard parts. Based on the bearing force determined in this way, further functions of the drive arrangement 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, comprising a crank drive, at least one bearing force sensor, in particular two bearing force sensors, and a detection unit.The crank mechanism comprises a crankset, a pedal spindle, and two bottom brackets for rotatably supporting the pedal spindle. For example, the pedal spindle can also be referred to as a crankshaft. The crankset comprises a crank and an output element connected to the crank in a rotationally fixed manner. 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 pedal spindle. The detection unit is configured to detect a bearing force at at least one of the two bottom brackets based on the force detected by the bearing force sensor, in particular the forces detected by the bearing force sensors.

[0009] In particular, the bearing force is considered to be the total resulting force in the area of ​​the bottom bracket, which occurs, for example, due to a motor torque and / or a rider torque. The detection unit is particularly preferably configured to determine a bearing force direction and a bearing force magnitude of the bearing force at the bottom bracket 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 pedal spindle at the level of the bottom bracket.

[0011] The crankset is particularly connected to the pedal shaft in a rotationally fixed manner. The crank mechanism preferably comprises another crank, which is also connected to the pedal shaft in a rotationally fixed manner. In particular, the pedal shaft is formed as a single piece. A crankset is considered to be a single-piece component, preferably consisting exclusively of the crank and the output element.

[0012] The cranks are designed to be connectable to pedals, particularly so that pedaling power can be transferred to the pedal shaft via the cranks.

[0013] In particular, the output element corresponds to a chainring. Alternatively, another output element may preferably be provided, which is configured for connection to a transmission element to enable torque transmission from the pedal shaft to a drive wheel of the vehicle, such as a pulley or the like.

[0014] In other words, a drive assembly is provided which has two bearing force sensors on the bottom bracket. Because the two bearing force sensors are distributed around the circumference, measured values ​​for forces in two mutually different directions are determined. This preferably makes it easy to determine a bearing force direction and a bearing force magnitude for the instantaneous bearing force at the bottom bracket. This determination of the bearing force direction and the bearing force magnitude is preferably based on a previously known relative installation position of the two bearing force sensors to one another, and in particular based on previously known measurement directions of the bearing force sensors along which the respective forces are measured.

[0015] 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.

[0016] For a particularly simple design, the two force sensors can preferably be identical in construction.

[0017] The drive arrangement thus offers the advantage of measuring the bearing force at the bottom bracket 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 are generally not or only very slightly susceptible to interference from magnetic fields, enables particularly reliable and precise measurement of the bearing force.

[0018] A further advantage of the drive assembly is that the direction and magnitude of the bearing force can be precisely determined regardless of the drive assembly's installation position on an electric bicycle. This means that the drive assembly can be mounted on the 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 bearing force sensors, the resulting bearing force can be precisely measured in any orientation of the drive assembly without the need to adapt the arrangement of the bearing force sensors to the installation position. The resulting bearing force can preferably be determined based on a simple, one-time calibration of the system.

[0019] By using a crankset in combination with the special bearing force detection system, the drive assembly offers the further advantage of enabling precise bearing force detection with a particularly simple and cost-effective design. This allows for an optimal range of functions, for example, with regard to use on an electric bicycle, which includes, for example, pedal force-dependent motor control. In particular, the special bearing force detection system allows for a particularly simple design of the crank drive with the crankset connected directly to the pedal shaft. The drive assembly is thus also characterized by low costs due to fewer and relatively simple components. Furthermore, this enables a low weight of the drive assembly.

[0020] The subclaims contain preferred developments of the invention. The bearing force sensors are preferably arranged in the axial direction of the pedal shaft at the level of the bottom bracket arranged on the output side. In other words, a drive assembly is provided which has the bearing force sensors in the region of that of the two bottom brackets which is arranged closer to the output element. This allows the bearing force, and in particular, an output force on the output element, to be determined particularly reliably.

[0021] Particularly preferably, the drive assembly further comprises a bearing receptacle that at least partially surrounds the bottom bracket in a ring-shaped manner. In particular, the bearing receptacle surrounds the bottom bracket substantially completely, preferably except for a predetermined gap. The bearing receptacle is particularly designed to hold the bottom bracket. For example, the bearing receptacle can be designed as a bearing shell.

[0022] Preferably, a radially bendable bending beam is formed on the bearing mount, with at least one of the two bearing force sensors being arranged on the bending beam. In particular, the bearing force sensor detects a force on the bending beam that may arise from a deformation of the bending beam caused by the bearing force. The use of the bending beam makes it possible to 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 deformations of the bending beam, whereby the forces can be detected easily and precisely. This allows small bearing forces, in particular, to be determined very precisely.When used on an electric bicycle, for example, this offers the advantage that small torque values ​​can be recorded precisely and sensitively, which enables particularly precise control of the motor drive unit depending on the rider's torque.

[0023] Preferably, a portion of the bearing mount is designed as a radially bendable bending beam. This means that the bending beam is an integral part of the bearing mount itself. This allows for a particularly simple design of the arrangement. The bearing mount preferably has a slot, in particular a radial slot. The bending beam is adjacent to the slot. In other words, the bending beam is formed by 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 design that enables the advantageous properties of the sensitive bending beam.

[0024] Particularly preferably, the bearing mount has two bending beams and one bearing force sensor per bending beam. Preferably, the two bending beams are 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. Preferably, the two bearing force sensors are arranged aligned in different directions in order to be able to detect bearing forces in different directions. Preferably, each of the two bearing force sensors is designed and arranged to detect a force in a tangential 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.

[0025] Preferably, the arrangement 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 bottom bracket 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.

[0026] Further preferably, the stop is arranged such that, in the unloaded state of the bottom bracket, a predetermined air gap is formed between a free end of the bending beam and the stop. The air gap in the unloaded state is preferably a maximum of 0.1 mm. The air gap thus allows the bending beam to be freely deformed until the stop is reached, enabling the bearing force to be measured particularly precisely. The air gap can be adjusted particularly easily, for example, during assembly of the arrangement by appropriately aligning the stop.

[0027] The drive arrangement preferably further comprises a motor configured to provide a motor torque to assist a driver torque applied by the driver. In particular, the motor is designed as an electric motor. The motor preferably has a motor shaft to which the generated motor torque is provided.

[0028] The drive arrangement preferably further comprises a gear unit arranged between the motor and the pedal shaft. The gear unit is designed to transmit torque between a motor shaft of the motor and the pedal shaft. The motor shaft is in particular an integral component of the motor. In particular, the gear unit thus effects a transmission ratio between the motor and the pedal shaft. In particular, this makes it possible to determine particularly reliably and directly the pedal force applied to the pedal shaft by the driver of the vehicle using muscle power. The gear unit is preferably a spur gear unit. The gear unit is particularly preferably a two-stage spur gear unit. The gear unit preferably comprises an intermediate shaft which is parallel to the motor shaft and the pedal shaft, and wherein torque is transmitted between the motor shaft and the pedal shaft indirectly via the intermediate shaft and respective gear pairs between the respective shafts.Preferably, the pedal shaft and the motor shaft are arranged coaxially with each other. Due to the coaxial arrangement of the pedal shaft and motor shaft, the drive assembly offers the advantage that the motor and pedal shaft can also be arranged coaxially. This enables a particularly compact design of the drive assembly. In particular, it allows the motor, which often takes up a significant portion of the overall installation space of the drive assembly, to be optimally positioned coaxially with the pedal shaft. This arrangement has a particularly advantageous effect on the compact overall design of the drive assembly, for example, if the largest gear of the transmission is arranged on the pedal shaft.Thus, for example, the remaining transmission volume can extend only slightly beyond the axial projection surface of the motor, allowing this volume to be comparatively narrow and, in particular, positioned relatively centrally in the axial direction, which has a further advantageous effect on the design of the drive assembly. Furthermore, the drive assembly is characterized by low costs due to fewer and relatively simple components. This also enables a low weight of the drive assembly.

[0029] Further preferably, the pedal shaft and the motor shaft 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 pedal shaft in the radial direction of the pedal shaft. This allows for a particularly flexible arrangement of the components of the drive assembly.

[0030] 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 pedal 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 to the right or left with respect to a direction of travel of the vehicle on which the drive arrangement can be arranged. The drive arrangement preferably further comprises a housing. The bearing receptacle has a fastening region which is fixed to the housing, in particular immovably. The housing can, for example, be a housing of the motor.By fixing the bearing mount to the housing, a precise, and particularly immovable, mounting of the bottom bracket relative to the housing is provided. The mounting area can, for example, be a section of the bearing mount 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 mount.

[0031] Preferably, the fastening area is fixed to the housing by means of a screw connection. In particular, the screw connection comprises a plurality of screws distributed around the circumference of the bearing support. Alternatively or additionally, the fastening area is preferably fixed to the housing by means of a welded connection and / or an adhesive connection and / or a press connection. The welded connection and / or adhesive connection is preferably formed over the entire surface of the fastening area in order to provide a particularly robust fixation.

[0032] More preferably, the assembly further comprises a fastening element by means of which the fastening region is fixed to the housing. This means that the bearing receptacle is fixed directly or indirectly to the housing by means of the fastening element. This allows for particularly simple and cost-effective manufacture and assembly of the assembly, for example, because precise alignment of the bearing receptacle and fastening element is enabled separately from the housing.

[0033] Particularly preferably, the fastening element is designed as a disk, which is preferably circular. The fastening element is arranged in a recess in the housing, in particular together with the bearing receptacle. The recess preferably has an inner geometry which corresponds to an outer geometry of the fastening element. This enables particularly simple and cost-effective construction and assembly of the arrangement. For example, the recess and fastening element can have geometries that are easy and precise to manufacture. 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 allows for a particularly simple, lightweight, and cost-effective design of the assembly. Furthermore, a particularly high positional accuracy of the bearing mount and thus of the bottom bracket can be achieved, since, for example, the recess in the housing can be manufactured with high precision in a simple and cost-effective manner. This is particularly advantageous when the housing is a deep-drawn component, preferably a sheet metal housing in which the recess is produced by deep drawing.

[0034] 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.Preferably, there is an axial distance between a remaining area of ​​the bending beam and the recess which is greater than the gap dimension, so that in particular a free movement of the bending beam is possible, and the bending beam only rests on the stop area.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Furthermore, the invention relates to a method for operating the drive arrangement described above. The method comprises the following steps:

[0040] - Determination of forces using the two bearing force sensors, and

[0041] - Determining a bearing force at the bottom bracket based on the forces measured by the bearing force sensors. This method is characterized by its particularly simple and cost-effective implementation, allowing precise results for the bearing force at the bottom bracket to be determined.

[0042] The method preferably further comprises the step of determining an output force on the output element based on the bearing force direction and the bearing force magnitude. The output force is considered to be a force exerted on the output element by a transmission element, such as a bicycle chain, 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.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.

[0043] 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.

[0044] Preferably, the bearing force direction and 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 in the mounted state of the drive assembly on an electric bicycle. Brief description of the drawings

[0045] 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. Here:

[0046] Figure 1 is a simplified schematic view of an electric bicycle with a drive arrangement according to a first embodiment of the invention,

[0047] Figure 2 is a sectional view of the drive arrangement of Figure 1,

[0048] Figure 3 is a simplified detailed sectional view of the drive arrangement of Figure 1 to illustrate the mode of operation,

[0049] Figure 4 is a perspective detailed view of the drive arrangement of Figure 1,

[0050] Figure 5 shows a further detailed view of the drive arrangement of Figure 1,

[0051] Figure 6 is a further detailed view of the drive arrangement of Figure 1,

[0052] Figure 7 is a sectional view of a drive arrangement according to a second embodiment of the invention,

[0053] Figure 8 is a sectional view of a drive arrangement according to a third embodiment of the invention, and

[0054] Figure 9 is a sectional view of a drive arrangement according to a fourth embodiment of the invention.

[0055] Preferred embodiments of the invention

[0056] 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 a sectional view in Figure 2. Details of the drive assembly 1 of the first embodiment are shown in Figures 3 to 5.

[0057] The drive assembly 1 has a crank mechanism 2 with a crankset 27. The crankset 27 consists of an output element 3, which is a chainring, and a crank 21. The crank 21 and the chainring are connected to one another in a rotationally fixed manner and, in particular, are formed together as a single-piece component. The crankset 27 is also rotationally fixedly connected to a pedal shaft 22 of the crank mechanism 2.

[0058] The crank mechanism 2 further comprises a further crank 21, which is arranged with respect to a pedal axis 22a at an end of the pedal shaft 22 opposite the crankset 27 and is also connected to the pedal shaft 22 in a rotationally fixed manner.

[0059] The use of a crankset 27 allows for a particularly simple and cost-effective construction and assembly of the drive assembly 1. Furthermore, standard parts can be used as cranksets 27.

[0060] Pedals 25 are arranged on the cranks 21, via which a driver can generate a driver torque on the drive arrangement 1 by means of muscle power.

[0061] The crank mechanism 2 further comprises two bottom brackets 23, 24 for rotatably supporting the pedal shaft 22.

[0062] In addition, the drive arrangement 1 comprises a bicycle chain 107 as a transmission element, which is in engagement with the chainring 3.

[0063] To support the rider's torque with additional motor torque, the drive assembly 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 configured to generate the motor torque. The drive assembly 1 is preferably attached to a bicycle frame 101 of the electric bicycle 100 by means of a housing 40.

[0064] The crankshaft 22 is mounted in the housing 40 by means of the two bottom brackets 23, 24. The housing 40 has a bearing collar 43 on the bottom bracket 23 facing away from the output shaft, within which the bottom bracket 23 is arranged (see Figure 2). In particular, the bearing collar 43 is an integral part of the housing 40.

[0065] In addition, the drive arrangement 1 comprises a gear 8. The gear 8 is configured to transmit torque between a motor shaft 42 of the motor 4 and the drive shaft 22.

[0066] The gear 4 is arranged along the direction of the pedal axis 22a between the motor 2 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 pedal shaft 22 and the motor 4 on the left side. In other words, the motor 4, apart from the left crank 22, forms the leftmost element of the drive assembly 1.

[0067] Gearbox 8 is a two-stage spur gear. This means that gearbox 8 comprises several gears designed as spur gears that mesh with each other to transmit torque. Their arrangement is described in more detail below.

[0068] In the drive assembly 1, the motor shaft 42 of the motor 4 and the pedal shaft 22 are arranged coaxially with each other. This means that the motor shaft 42 and the pedal shaft 22 are each arranged to rotate about the common pedal axis 22a. For this purpose, the motor shaft 42 of the motor 4, which is in particular connected in a rotationally fixed manner to a rotor of the motor 4, is designed as a hollow shaft. The pedal shaft 2 extends through the motor shaft 42.

[0069] Pedal shaft 22 and motor shaft 42 are mounted for rotation relative to each other by means of bearings 48. The motor shaft 42 of the motor 4 projects axially beyond the rotor of the motor 4. A motor toothing 84 is formed on this projecting portion of the motor shaft 42.

[0070] The motor gearing 84 engages with a first gear 81 of the transmission 8. The first gear 81 is connected in a rotationally fixed manner to an intermediate shaft 85 of the transmission 8. The intermediate shaft 85 extends along an intermediate shaft axis 80 and is arranged to be freely rotatable about this intermediate shaft axis 80.

[0071] In addition, the transmission 8 includes a second gear 82, which is also rotationally fixedly connected to the intermediate shaft 85. Preferably, the first gear 81, the second gear 82, and the intermediate shaft 85 can be formed together as a single, integral component, or alternatively as separate, interconnected components.

[0072] In addition, the gear 8 includes a third gear 83, which is arranged to rotate about the pedal axis 22a. Between the third gear 83 and the pedal shaft 22 is a freewheel 89, which allows either a rotationally fixed connection or a freely rotatable arrangement of the third gear 83 and the pedal shaft 22.

[0073] The torque transmission of the motor torque generated by the motor 4 can thus take place from the motor shaft 42 via the motor toothing 84 and the first gear 81 to the intermediate shaft 85 and via the second gear 82 and the third gear 83 and the correspondingly switched freewheel 89 to the pedal shaft 22.

[0074] The drive arrangement 1 offers the advantage of enabling a particularly compact design of the drive arrangement 1 thanks to the coaxial arrangement of the motor 4 and the treadle shaft 22. The motor 4, which geometrically forms the largest element of the drive arrangement 1, can be positioned particularly advantageously thanks to the coaxial arrangement to the treadle shaft 22. In addition, since the special design of the gear 8 means that the largest gear, namely the third gear 83, is also arranged on the treadle shaft 22, a particularly small extension of the other parts of the drive arrangement 1 in the radial direction with respect to the treadle axis 22a is possible, since the remaining gear volume extends only slightly out of an axial projection surface of the motor 4.

[0075] Between the motor 4 and the transmission 8 is also a printed circuit board 9, which is part of the drive assembly 1. The printed circuit board 9 can, for example, comprise a control unit or be designed as part of a control unit. In particular, the printed circuit board 9 is arranged between the motor 4 and the first gear 81 of the transmission with respect to the direction of the pedal axis 22a.

[0076] The drive assembly 1 also has a connection element 90, which can be designed, for example, as a plug for an electrical connector. The connection element 90 is connected to the circuit board 9 and is arranged protruding from the circuit board 9 in the axial direction, away from the output.

[0077] During motor-assisted operation of the electric bicycle 100, the motor torque is 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 bottom bracket 24, as described below.

[0078] 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 3) causes a reaction force of the same magnitude and parallel to it in the opposite direction on the output-side bottom bracket 24.

[0079] 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.

[0080] 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 area of ​​the output-side bottom bracket 24.

[0081] The arrangement of the two bearing force sensors 51, 52 is shown in Figures 3 and 4. Both bearing force sensors 51, 52 are located in the axial direction of the pedal shaft 22 at the level of the output-side bottom bracket 24.

[0082] 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.

[0083] The two bearing force sensors 51, 52 are connected to a detection unit 6, which determines the respective forces 55, 56 and also determines all other forces and moments.

[0084] 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 circular outer geometry.

[0085] Figure 4 shows a perspective view of the bearing holder 5.

[0086] The bottom bracket 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 bottom bracket 24. The bearing support 5 is also slotted, with a slot 57 that extends radially completely through the entire bearing support 5.

[0087] The bearing support 5 also has a fastening area 50 that is fastened to the housing 40. The fastening area 50 is an axial end face of the bearing support 5, which is in full contact with a fastening element 50a that is fixed to the housing 40.

[0088] The bearing mount 5 is arranged in a recess 65 of the housing 4 (see Figure 6). The recess 65 is circular and arranged coaxially with the pedal axis 22a. The recess 65 can, for example, be stepped, as can be seen in Figure 6, and extend completely through a wall of the housing 4. The pedal shaft 22 (not shown in Figure 6) protrudes completely through the recess 65 of the housing 4.

[0089] In addition, the assembly 10 includes a separate fastening element 50a, by means of which the bearing support 5 is fixed in the housing 4. The fastening element 50a is a circular annular disc, which can be made of metal, for example.

[0090] The bearing support 5 is fixed to the fastening element 50a at the fastening area 50 by means of a welded joint 58b. The welded joint 58b extends over the entire fastening area 50, ensuring a firm and reliable connection. Similar to the first embodiment, a small axial clearance exists between the flexural beams 53 of the bearing support 5 and the fastening element 50a to ensure unhindered mobility of the flexural beams 53.

[0091] The fastening element 60 has an outer diameter corresponding to the inner diameter of the recess 65.

[0092] The fastening element 50a is immovably fixed to the housing 40, for example, by means of a press connection and / or a welded connection and / or an adhesive connection. Thus, the fastening element 50a indirectly secures the bearing support 5 to the housing 40 of the motor 4.

[0093] In addition, the bearing support 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. In Figure 4, the bending beams 53 are indicated by hatching.

[0094] On the radially outer side of each bending beam 53 there is a flat flattening 41 on which the respective bearing force sensor 51, 52 is arranged.

[0095] The bearing receptacle 5 is designed and fixed to the fastening element 60 in such a way that a radially outer dimension 53b of the free end 53a of the bending beam 53 is smaller by a predetermined gap dimension 53c (see Figure 4) than an outer dimension of the fastening element 60 and thus also smaller than an inner dimension 65a of the recess 65. This causes the inner circumference of the recess 65 to act as a stop. 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 abutting the inner circumference of the recess 65. This provides a particularly simple and lightweight design for the drive arrangement 1. Furthermore, it is particularly simple and cost-effective to manufacture.

[0096] If the crank mechanism 2 is loaded by the rider's pedaling force, this causes the bearing force 59 on the bottom bracket 24. Since the bottom bracket 24 is held in the housing 40 of the motor 4 by means of the bearing mount 5, this bearing force 59 has a corresponding effect on the bearing mount 5. Due to the special design of the bearing mount 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 means of the bearing force sensors 51, 52 designed as strain gauges. Using the previously known geometric and mechanical properties of the arrangement 10 described above, the total resulting bearing force 59, namely the bearing force direction and the bearing force magnitude, can be determined based on the detected deformations.

[0097] The free movement of the bending beams 53 in the radial direction enables particularly sensitive detection with appropriate mechanical design. This means, for example, that by appropriately designing the thickness of the bending beams 53 in the axial and / or radial directions, a clearly measurable deformation can occur even with small bearing forces. In particular, this enables the detection of low torques applied by the driver with high accuracy.

[0098] To ensure particularly high precision by minimizing the influence of deformation on the bending beams 53, the bending beams 53 are spaced apart in the axial direction from the fastening element 50a, against which the fastening region 50 of the bearing support 5 rests. This means that in the axial direction, a gap exists between an axial end face 50b of each bending beam 53 facing the fastening element 50a and the fastening element 50a, against which the end face 50a of the fastening region 50 rests. As a result, the deformation of the bending beam 53 is not influenced by friction, for example.

[0099] Furthermore, the bending beams 53 and / or the bottom bracket 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 bottom bracket 24, so that, for example, a falsification of the measurement results due to stresses caused by static friction can be avoided or reduced.

[0100] Furthermore, the drive arrangement 1 comprises a stop 7, which limits the movement of each bending beam 53 in the radial direction. The stop 7 is formed by the housing 40. The stop 7 is located in an extension of the slot 57. 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.

[0101] 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.

[0102] 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.

[0103] During calibration, the crank drive 2 can be arranged in a first step 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 a previously known actuating force. The actuating force is oriented vertically, i.e., orthogonal to the crank 21 and the chain direction 70. As a result, the entire actuating force is transferred to the bicycle chain 107. A corresponding bearing force 59 corresponds to a resultant force of the actuating force and the output force 60.

[0104] In a second calibration step, the crank mechanism 2 is 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., orthogonal to the chain device 70 and parallel to the crank 21. In this second actuating configuration, the output force 60 is zero due to the corresponding orientation of the crank mechanism 2. However, the actuating force still generates a bearing force 59.

[0105] Based on the forces 55, 56 of the bearing force sensors 51, 52 recorded in both calibration steps, a relationship between 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.

[0106] Figure 7 shows a sectional view of a drive arrangement 1 according to a second exemplary embodiment of the invention. The second exemplary embodiment essentially corresponds to the first exemplary embodiment with the difference of an alternative arrangement of the components of the drive arrangement 1. In the second exemplary embodiment, the motor 4 is arranged on the output side, i.e. between the transmission 8 and the output interface 35. In detail, the motor 4 is arranged between the output-side bottom bracket 24 and the first gear 81 of the transmission 8. This means that the motor 4 is located on the right with respect to the direction of travel A. This makes it possible to provide an alternative geometric arrangement of the components of the drive arrangement 1. In the second exemplary embodiment, the connection element 90 on the circuit board 9 is also arranged protruding towards the output side.

[0107] Figure 8 shows a detailed view of a drive arrangement 1 according to a third embodiment of the invention. The third embodiment essentially corresponds to the first embodiment, with the difference that motor 4 and pedal shaft 22 are arranged non-coaxially. In the third embodiment of Figure 8, the motor 4 is arranged next to the pedal shaft 22 in the radial direction of the pedal shaft 22. This means that a motor axis 49, about which the motor 4 and the motor gearing 84 are rotatable, is arranged parallel to the pedal axis 22a and at a distance from it. The further design of the transmission 8 with intermediate shaft 85 is essentially analogous to the above description of the transmission 8 of the first embodiment.

[0108] Furthermore, in the third embodiment of Figure 8, the motor 4 is located on the side of the transmission 8 facing away from the output interface 35, i.e., on the left with respect to the direction of travel A. Figure 9 shows a detailed view of a drive arrangement 1 according to a fourth embodiment of the invention. The fourth embodiment essentially corresponds to the third embodiment of Figure 8, i.e., with a parallel arrangement of the motor 4 and crankshaft 22 next to one another, with the difference that the motor 4 is arranged on the right with respect to the direction of travel A.

[0109] That is, in the fourth embodiment, the motor 4 is arranged between the output interface 35 and the transmission 8 with respect to the direction of the pedal axis 22a.

Claims

Claims 1 . Drive arrangement of a vehicle (100) operable with muscle power and / or motor power, in particular an electric bicycle, comprising: - a crank mechanism (2) with a crankset (27), a pedal shaft (22), and two bottom brackets (23, 24) for supporting the pedal shaft (22), - wherein the crankset (27) comprises a crank (21) and an output element (3) connected in a rotationally fixed manner to the crank (21), - 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 (6) which is configured to detect a bearing force on at least one bottom bracket (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 bearing force sensor (51) is arranged in the axial direction of the pedal shaft (22) at the level of the bottom bracket (24) arranged on the output side.

4. Drive arrangement according to one of the preceding claims, further comprising a bearing receptacle (5) which at least partially surrounds the bottom bracket (24) in a ring shape.

5. Drive arrangement according to claim 4, wherein a bending beam (53) which can be bent in the radial direction is formed on the bearing holder (5), wherein at least one of the bearing force sensors (51, 52) is arranged on the bending beam (53).

6. Drive arrangement according to claim 4 or 5, 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).

7. Drive arrangement according to one of claims 4 to 6, 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).

8. Drive arrangement according to one of claims 5 to 7, further comprising a stop (7) which limits a movement of the bending beam (53) in the radial direction.

9. Drive arrangement according to claim 8, wherein the stop (7) is arranged such that in the unloaded state of the bottom bracket (24) a predetermined air gap (70) is arranged between a free end (53a) of the bending beam (53) and the stop (7).

10. Drive arrangement according to one of the preceding claims, further comprising a motor (4) which is arranged to provide a motor torque to assist a driver torque applied by a driver.

11. Drive arrangement according to claim 10, further comprising a gear (8) which is arranged between the motor (4) and the pedal shaft (22) and is adapted to transmit torque between a motor shaft (42) of the motor (4) and the pedal shaft (22).

12. Drive arrangement according to claim 11, wherein the pedal shaft (22) and the motor shaft (42) are arranged coaxially to one another.

13. Drive arrangement according to claim 11, wherein the pedal shaft (22) and the motor shaft (42) are arranged parallel to each other and at a predetermined distance from each other.

14. Drive arrangement according to one of claims 11 to 13, wherein the motor (4) is arranged on a side of the transmission (8) facing away from the output element (3), or wherein the motor (4) is arranged on a side of the transmission (8) facing the output element (3).

15. 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.

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

17. A method for operating a drive arrangement (1) according to one of claims 1 to 15, comprising the steps: - Determining a force (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 bottom bracket (24) based on the force (55, 56) detected by the bearing force sensor (51, 52).

18. The method of claim 17, further comprising the steps: - determining an output force (60) on the output element (3) based on the bearing force direction and the bearing force amount of the bearing force (59), and - Determining the driver torque applied by the driver based on the output force (60) and an engine torque of the drive unit (4).

19. The method according to any one of claims 17 or 18, further comprising the step: - Controlling a motor torque generated by the motor (4) as a function of the bearing force direction and the bearing force amount.

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