Arrangement for measuring a bearing force of a bottom bracket of a vehicle which can be operated by means of muscle power and / or motor power

Abstract

The invention relates to an arrangement (10) for measuring a bearing force of a bottom bracket (24) of a vehicle (100) which can be operated by means of muscle power and / or motor power, the arrangement comprising a bottom bracket (24), a bearing receptacle (5), which at least partly annularly engages around the bottom bracket (24), a bearing force sensor (51), and a measuring unit (6), wherein a flexible bar (53) which is bendable in a radial direction is formed on the bearing receptacle (5), wherein the bearing force sensor (51) is designed to detect a deformation of the flexible bar (53), and wherein the measuring unit (6) is designed to measure a bearing force on the bearing bracket (24) on the basis of the deformation of the flexible bar (53), which has been detected by means of the bearing force sensor (51).

Description

[0001] Description

[0002] title

[0003] Arrangement for detecting a bearing force of a bottom bracket 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 an electric bicycle, an electric bicycle 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 a 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 at a bottom bracket 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 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. Furthermore, for example, a simple determination of the bearing force can be enabled independently of the orientation of a drive unit, for example on a bicycle frame of an electric bicycle. Based on the bearing force thus determined, further functions of a drive arrangement can advantageously be provided efficiently and cost-effectively. This is achieved by an arrangement for detecting a bearing force of a bottom bracket of a vehicle operable with muscle power and / or motor power, comprising a bottom bracket, a bearing receptacle which at least partially surrounds the bottom bracket in a ring-shaped manner, a bearing force sensor, and a detection unit.In particular, the bearing mount essentially completely surrounds the bottom bracket, preferably except for a predetermined gap. The bearing mount is particularly designed to hold the bottom bracket. For example, the bearing mount can be designed as a bearing shell. A bending beam that is bendable in the radial direction, in particular on one side, is formed on the bearing mount. The bearing force sensor is designed to detect deformation, i.e. in particular bending, of the bending beam. The detection unit is also designed to detect a bearing force on the bottom bracket based on the deformation of the bending beam detected by the bearing force sensor. The bearing force is considered to be in particular 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.Particularly preferably, the detection unit is configured to determine a bearing force direction and a bearing force amount of the bearing force at the bottom bracket based on the detected deformation of the bending beam.

[0009] In other words, an arrangement is provided which has a bearing receptacle on the bottom bracket, on which an at least partially flexible region in the form of a bending beam is provided. As a result, the mechanical loads acting on the bottom bracket are transferred from the bottom bracket to the bending beam, which can deform the latter. In particular, the bending beam is designed to be freely movable on one side in the radial direction. This deformation can be detected by the bearing force sensor. By evaluating the measured values ​​of the bearing force sensor using the detection unit, the bearing force acting on the bottom bracket can then be determined. For example, the relationship between deformation and bearing force can be determined based on previously known geometric and mechanical properties of the bearing receptacle and bottom bracket. Alternatively or additionally, the bearing force can be determined based on a calibration of the system.

[0010] A variety of sensors can be used as bearing force sensors, suitable for detecting deformations of the bending beam. For example, the deformations can be detected directly and / or indirectly based on the forces acting on the bending beam.

[0011] The arrangement therefore offers the advantage that the bearing force at the bottom bracket can be measured using a particularly simple, cost-effective and space-saving design. The use of the bending beam enables a particularly sensitive design. 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, which can be measured easily and precisely. This means that small bearing forces in particular can be determined very precisely. When used on an electric bicycle, this offers the advantage that small torque values, for example, can be measured precisely and sensitively. This enables, for example, particularly precise control of a drive unit depending on the rider's torque.

[0012] The subclaims contain preferred developments of the invention.

[0013] 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 assembly.

[0014] 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.

[0015] 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. 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 a shaft, for example a crankshaft, crankshaft, output shaft or the like.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.

[0016] 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, slight deformability of the bending beam can be provided at low bearing forces, with the stop preventing excessive deformation. Further preferably, the stop is arranged such that, when the bottom bracket is in the unloaded state, 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 detection based on this can be enabled with particular precision. The air gap can be adjusted particularly easily, for example, during assembly of the arrangement by appropriately aligning the stop.

[0017] The arrangement preferably further comprises a housing. The bearing receptacle has a fastening region that is fixed to the housing, in particular immovably. The housing can be, for example, a housing of a drive unit. By fixing the bearing receptacle to the housing, a precise, and in particular immovable, mounting of the bottom bracket relative to the housing is provided. The fastening region can, for example, be a section of the bearing receptacle that, along the circumferential direction, corresponds to at least one-third, preferably at least half, and preferably at most three-quarters, of the entire ring of the bearing receptacle.

[0018] 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.

[0019] More preferably, the arrangement 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 makes it possible to provide particularly simple and cost-effective manufacture and assembly of the arrangement, for example because precise alignment of the bearing receptacle and fastening element separate from the housing is enabled. Particularly preferably, the fastening element is designed as a disc, which is preferably circular. The fastening element is arranged, in particular together with the bearing receptacle, in a recess in the housing. The recess preferably has an internal geometry which corresponds to an external geometry of the fastening element. This makes it possible to design and assemble the arrangement particularly simple and cost-effective.For example, the recess and fastening element can have geometries that are easy and precise to manufacture.

[0020] 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 bottom bracket 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.

[0021] 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 from the preferably circular outer contour of the fastening element. The gap is preferably a maximum of 0.5 mm, preferably a maximum of 0.2 mm, in particular at least 0.01 mm. The housing thus 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 a gap between a remaining area of ​​the bending beam and the recess which is larger than the gap size, so that in particular a free movement of the bending beam is possible, and the bending beam only rests on the stop area.

[0022] 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.

[0023] 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.

[0024] 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 a transmission shaft, preferably an intermediate shaft, for example, of a multi-stage transmission. This allows several functions to be fulfilled simultaneously in a simple and cost-effective manner using a small number of components.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The invention further relates to a drive arrangement of a vehicle operable with muscle power and / or motor power, in particular an electric bicycle, comprising a crank drive having cranks, a shaft, for example a pedal shaft, and two bottom brackets for supporting the shaft. Furthermore, the drive arrangement comprises an output element connected to the shaft and a drive unit configured to provide a motor torque to assist a rider torque generated by a rider, in particular by means of muscle power. Preferably, a chainring can be provided as the output element. Alternatively, another output element can preferably be provided that is configured to be connected to a transmission element in order to enable torque transmission from the shaft to a drive wheel of the vehicle. The shaft is mounted within the drive unit by means of the two bottom brackets.The drive assembly further comprises the above-described arrangement for detecting a bearing force at one of the two bottom brackets. The bearing force sensor is arranged in the axial direction of the 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 sensor in the region of that of the two bottom brackets which is arranged closer to the output element. Preferably, the output element is connected to the shaft in a rotationally fixed manner. In particular, the shaft is designed as a single piece. Determining the bearing force using the bearing force sensor has the advantage that the shaft can be designed in a particularly simple and cost-effective manner, while still allowing reliable determination of the forces used to actuate the drive unit.

[0029] The bearing receptacle preferably has the holding region, which is ring-shaped. In addition, the drive arrangement further comprises a gear with an intermediate shaft and with an intermediate shaft bearing. For example, the gear can be designed as a multi-stage gear, in particular as a spur gear. The holding region of the bearing receptacle forms a bearing seat for the intermediate shaft bearing. This means that the intermediate shaft bearing is held in a defined manner on the housing by the holding region. This makes it possible to provide a lightweight drive arrangement with a particularly simple and cost-effective design and manufacturability using few components, in which particularly tight tolerances can be maintained in the arrangement of the bearings and shafts.

[0030] Furthermore, the invention leads to a vehicle operable by muscle power and / or motor power, in particular an electric bicycle, comprising the described drive arrangement. Furthermore, the invention relates to a method for operating one of the drive arrangements described above. The method comprises the steps:

[0031] - Determining a deformation of the bending beam, and

[0032] - Determining the bearing force direction and magnitude of a resulting bearing force at the output-side bottom bracket based on the determined deformation. This method is characterized by its particularly simple and cost-effective implementation, allowing precise results for the bearing force direction and magnitude at the output-side bottom bracket to be determined.

[0033] 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.

[0034] 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.

[0035] Preferably, the method further comprises the step of controlling a motor torque generated by the drive unit as a function of the bearing force direction and the bearing force magnitude. Particularly preferably, the drive unit is controlled as a function of the determined rider torque. This means that a motor torque is provided to assist the rider's pedaling power as a function of the bearing force, or rather, the rider torque, which is determined based on the determined bearing force.

[0036] 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.

[0037] Short description of the drawings

[0038] 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:

[0039] Figure 1 is a simplified schematic view of an electric bicycle with a drive arrangement according to a first embodiment of the invention,

[0040] Figure 2 is a detailed sectional view of the drive arrangement of Figure 1, Figure 3 is a perspective detailed view of the drive arrangement of Figure 1,

[0041] Figure 4 shows a further detailed view of the drive arrangement of Figure 1,

[0042] Figure 5 is a perspective view of a detail of the drive arrangement of Figure 1,

[0043] Figure 6 is a further detailed view of the drive arrangement of Figure 1,

[0044] Figure 7 shows a further detailed view of the drive arrangement of Figure 1 with an alternative orientation of the drive unit,

[0045] Figure 8 is a detailed sectional view of a drive arrangement according to a second embodiment of the invention,

[0046] Figure 9 is a perspective view of a detail of the drive arrangement of Figure 8,

[0047] Figure 10 is an alternative perspective view of the detail of Figure 9,

[0048] Figure 11 is a simplified schematic view of a detail of a

[0049] Drive arrangement according to a third embodiment of the invention,

[0050] Figure 12 is a perspective view of a detail of the drive arrangement of Figure 11, and

[0051] Figure 13 is a further perspective view of a detail of the drive arrangement of Figure 11.

[0052] Preferred embodiments of the invention

[0053] 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 detailed sectional view in Figure 2.

[0054] 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.

[0055] In addition, the crank drive 2 comprises a shaft, for example pedal shaft 22, which is connected in a rotationally fixed manner to the cranks 21, and two bottom brackets 23, 24 for the rotatable mounting of the pedal shaft 22.

[0056] The drive arrangement 1 further comprises an output element 3, which is a chainring, and which is connected in a rotationally fixed manner to the pedal shaft 22, and a bicycle chain 7 as a transmission element, which is in engagement with the chainring 3.

[0057] In order to support the driver torque with an additional engine torque, the drive arrangement 1 comprises a drive unit 4 which is designed to generate the engine torque, preferably by means of an electric motor which is supplied with electrical energy in particular by an electrical energy storage device (not shown).

[0058] The drive unit 4 is preferably attached to a bicycle frame 101 of the electric bicycle 100.

[0059] The drive shaft 22 is mounted in the drive unit 4 by means of the two bearings 23, 24. The drive unit 4 has a bearing collar 43 on the bearing 23 facing away from the output, within which the bearing 23 is arranged (see Figure 2). In particular, the bearing collar 43 is an integral part of a housing 40 of the drive unit 4.

[0060] 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.

[0061] 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 drive unit 4 are used. In detail, the relationship used is that an output force 60 relevant to the propulsion of the electric bicycle 100 causes a reaction force of the same magnitude and parallel to it in the opposite direction at the output-side bottom bracket 24.

[0062] With knowledge of the geometry and mechanics of the crank mechanism 2 and the engine torque of the drive unit 4, a portion of the output force 60 generated by the drive unit 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.

[0063] 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.

[0064] 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.

[0065] Each of the two bearing force sensors 51, 52 is designed as a strain gauge and configured to detect a force 55, 56, resulting, for example, from mechanical expansion and / or compression, along precisely one predetermined direction, namely in the radial direction relative to the pedal axis 22a. 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.

[0066] 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 drive unit 4 and is designed, in particular, as a bearing shell. In the first exemplary embodiment, the bearing support 5 has a substantially square outer geometry.

[0067] Figure 5 shows a perspective view of the bearing holder 5.

[0068] The bottom bracket 24 is arranged in a recess of the bearing receptacle 5, wherein in the unloaded state preferably substantially the entire inner circumference of the bearing receptacle 5 is in contact with an outer circumference of the bottom bracket 24.

[0069] The bearing holder 5 is also slotted, with a slot 57 which extends completely through the entire bearing holder 5 in the radial direction.

[0070] 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 the housing 40. In the first exemplary embodiment, the fastening area 50 is fixed to the housing 40 by means of a total of three screw connections 58a.

[0071] 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. On the radially outer side of each bending beam 53 there is a flattened area 41 on which the respective bearing force sensor 51, 52 is arranged.

[0072] If the crank mechanism 2 is loaded by the rider's pedaling force, this causes a bearing force 59 on the bottom bracket 24. Since the bottom bracket 24 is held in the housing 40 of the drive unit 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.

[0073] Based on 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.

[0074] 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.

[0075] In order to ensure particularly high accuracy by ensuring that the deformation of the bending beams 53 is as unaffected as possible, the bending beams 53 are spaced apart in the axial direction from the housing wall against which the fastening region 50 of the bearing mount 5 rests. This means that in the axial direction, there is a gap between an axial end face 50b of each bending beam 53 facing the housing wall and the housing wall against which the end face 50a of the fastening region 50 rests. As a result, the deformation of the bending beams 53 is not influenced by friction, for example. 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, falsification of the measurement results due to stresses caused by static friction can be avoided or reduced.

[0076] Furthermore, the arrangement 10 comprises a stop 7, which limits the movement of each bending beam 53 in the radial direction. The stop 7 is immovably fixed to the housing 40 of the drive unit 4. The stop 7 is located as an extension of the slot 57 and has a stop surface 75 for each bending beam 53, against which the free ends 53a of the bending beams 53 can bear substantially in the radial direction when the bending beams 53 deform in the radial direction. In particular, the stop surfaces 75 are arranged parallel to the flattened portions 41 of the bending beams 53 in the unloaded state.

[0077] The stop 7 is designed and fixed to the housing 4 such that, in the unloaded state, i.e., when the bottom bracket 24 is not loaded, a predetermined air gap 70 exists between each free end 53a or between each flattened portion 41 of each bending beam 53 and the respective stop surface 75. This allows the bending beams 53 to deform completely freely until they rest against the stop 7. The stop 7 can provide a particularly high level of mechanical robustness for the assembly 10.

[0078] In order to be able to determine the output force 60 acting on the bicycle chain 7 based on the determined bearing force 59, and thus also the rider torque as described above, it is necessary to know the relative orientation of the chain device 70 of the bicycle chain 7 and the drive unit to one another, i.e., the installation position of the drive unit 4 on the bicycle frame 101. This is illustrated by Figures 6 and 7, which show different installation positions of the drive unit 4.

[0079] As can be seen in Figures 6 and 7, there are different

[0080] Alignments of the chain direction 70 and the drive unit 4 relative to each other are provided. In order to correctly determine the output force 60 based on the bearing force 59, knowledge of the geometric relationship between the drive unit 4 and the chain direction 70 is necessary.

[0081] For this purpose, a one-time calibration of the drive assembly 1 is performed. During the calibration, no motor torque is generated by the drive unit 4.

[0082] During calibration, in a first step, the crank drive 2 can be arranged such that the cranks 21 are aligned horizontally, i.e., parallel to the chain direction 70. 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 the chain direction 70, and is applied by the rider actuating the pedal. As a result, the entire actuating force is transferred to the bicycle chain 7. A corresponding bearing force 59 corresponds to a resultant force from the actuating force and the output force 60. Calibration preferably takes place after the drive unit 4 has been mounted in a bicycle frame 101 of the electric bicycle 100.Particularly preferably, the crank 21 is actuated with a predetermined, precisely known actuating force, so that the amount of the output torque can be determined precisely.

[0083] In a second calibration step, the crank mechanism 2 is arranged so that the cranks 21 are aligned vertically, i.e., orthogonal to the chain mechanism 70. In this second calibration configuration, the lower crank 21 is actuated with an actuation force that is also aligned vertically, i.e., orthogonal to the chain mechanism 70 and parallel to the crank 21. As above, the actuation force is applied by the rider pressing the pedal 25. In this second actuation configuration, the output force 60 is zero due to the corresponding orientation of the crank mechanism 2. However, the actuation force still generates a bearing force 59.

[0084] 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 7. This also allows the orientation of the drive unit 4 relative to the bicycle chain 7 to be determined. The orientation thus determined can then be used as the basis for determining the rider torque based on the bearing force direction and the bearing force magnitude of the bearing force 59.

[0085] Figure 8 shows a detailed sectional view of a drive assembly 1 according to a second embodiment of the invention. The second embodiment essentially corresponds to the first embodiment with an alternative configuration of the fastening and arrangement of the bearing support 5 in the housing 40 of the drive unit 4. Figures 9 and 10 show further detailed views of the drive assembly 1 of the second embodiment.

[0086] In the second embodiment, the bearing mount 5 is arranged in a recess 65 of the housing 4. 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 8, and extend completely through a wall of the housing 4. The pedal shaft 22 (not shown in Figure 8) protrudes completely through the recess 65 of the housing 4.

[0087] In addition, the assembly 10 in the second embodiment includes a separate fastening element 60, by means of which the bearing support 5 is fixed in the housing 4. The fastening element 60 is a circular annular disc, which can be made of metal, for example.

[0088] The bearing support 5 is fixed to the fastening element 60 at the fastening area 50 by means of a welded joint 58b. The welded joint 58b extends over the entire fastening area, ensuring a firm and reliable connection. Similar to the first embodiment, a small axial gap is provided between the flexural beams 53 of the bearing support 5 and the fastening element 60 to allow unhindered movement of the flexural beams 53. The fastening element 60 has an outer diameter corresponding to the inner diameter of the recess 65.

[0089] The fastening element 60 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 60 indirectly secures the bearing support to the housing 40 of the drive unit 4.

[0090] 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 9) 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 makes it possible to provide a particularly simple and lightweight design for the drive arrangement 1. Furthermore, it is particularly simple and cost-effective to manufacture.

[0091] Figure 11 shows a simplified schematic view of a detail of a drive assembly 1 according to a third embodiment of the invention. Figures 12 and 13 show further views of the drive assembly 1 of the third embodiment. The third embodiment essentially corresponds to the second embodiment of Figures 8 to 10, with the difference of an alternative design of the bearing support 5 and the housing 40.

[0092] In the third exemplary embodiment, the housing 40 is preferably designed as a solid sheet metal housing. In other words, the housing 40 is formed from one or more deep-drawn components. The recess 65, in which the bearing receptacle 5 is arranged, is formed by the deep-drawing process. This can be seen, for example, in Figure 12. In the third exemplary embodiment, the bearing receptacle 5 additionally has a holding region 54, which is of annular design. The holding region 54 and the base region of the bearing receptacle 5, which is also of annular design and forms the bearing seat for the bottom bracket 24, together form a one-piece component, which is essentially shaped like an "8".

[0093] The holding area 54 has a further recess 54b, which is designed in particular as a circular through-opening. The recess 54 is coaxial with an intermediate shaft axis 22b, which is parallel to the pedal axis 22a.

[0094] 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 54, in particular by means of a press connection.

[0095] 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 22d that corresponds to a straight line connecting the two axes 22a, 22b. The undercut is identified in Figure 11 by reference numeral 54a.

[0096] In the third exemplary embodiment, a precise, unambiguous fixation of the bearing support 5 in the housing 40 is achieved by the outer circumference of the bearing support 5 and by the inner edge 65b of the recess 65. In particular, the outer circumference of the bearing support 5 in the third exemplary embodiment forms the fastening area 50 for fixing the bearing support 5 to the housing 40.

[0097] The special geometry with the undercut 54a along the direction 22d thus achieves a precisely defined relative position of the bearing support 5 and the housing 40 in a particularly simple and cost-effective manner using few components. In particular, this enables the special geometry with the gap 53c, namely such that the free ends 53a of the bending beams 53 of the bearing support 5 are arranged in the predetermined gap 53c with respect to the inner dimension 65a of the recess 65 of the housing 40.

[0098] The recess 54b of the holding area 54 of the bearing support 5 forms a further bearing seat for another bearing (not shown). This is preferably a bearing seat for an intermediate shaft bearing, by means of which an intermediate shaft of a transmission (not shown) of the drive assembly 1 can be mounted. This enables the integration of several functions with particularly small positional tolerances in a particularly simple and cost-effective manner.

[0099] In particular, the recess 54b can be provided as a bearing seat for any bearing of any shaft.

[0100] As can be seen in Figure 12, the recess 65 of the housing 40 is formed with several different sub-areas. A holding area recess 65d is provided for receiving the holding area 54 of the bearing support 5. This holding area recess 65d is formed as a depression that does not completely penetrate the housing 40.

[0101] In the area of ​​the base of the bearing receptacle 5, which serves as the bearing seat for the bottom bracket 24, the recess 65 has a first shoulder 65c, which is designed, for example, similar to the fastening area 50 of the second exemplary embodiment of Figures 8 to 10 (see in particular Figure 10), and against which the bearing receptacle 5 rests flatly. In addition, the recess 65 has a second shoulder 65b, which is recessed compared to the first shoulder 65c in order to prevent mechanical contact between the bearing receptacle 5 and the housing 40 in this area. Furthermore, the recess 65 has a through-opening for the passage of the bottom bracket shaft 22.

[0102] Figure 13 shows an example of a fully assembled assembly comprising bearing support 5 and housing 40. Bearing support 5 is pressed into recess 65 of housing 40 and then secured axially in the housing by means of several securing regions 5c, particularly in a form-fitting manner. The securing regions 5c are preferably created by plastically deforming portions of housing 40, for example, by caulking. This allows for particularly simple, time-efficient, and cost-effective assembly of drive assembly 1.

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