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

Abstract

The invention relates to a drive assembly (1) of a vehicle (100) which can be driven by muscle power and / or motor power, in particular an electric bicycle, comprising an output shaft (22) which is designed to be connected to cranks (21) of a crank drive (2), a motor (4) which is designed to generate a motor torque in order to support an operator torque, which is applied by an operator, on the output shaft (22), a motor shaft (42) of the motor (4) being coaxial to the output shaft (22), at least one bearing (24), by means of which the output shaft (22) is supported, at least one bearing force sensor (51, 52), in particular two bearing force sensors (51, 52), said bearing force sensor (51, 52) being designed to detect a force (55, 56), and a detection unit (6) which is designed to detect a bearing force (59) on the bearing (24) on the basis of the force (55, 56) detected by the bearing force sensor (51, 52).

Description

[0001] Description

[0002] title

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

[0004] State of the art

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

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

[0007] Disclosure of the invention

[0008] The drive arrangement according to the invention with the features of claim 1 is distinguished in that a bearing force on a bearing of a vehicle operable with muscle power and / or motor power can be precisely determined in a particularly simple and cost-effective manner. Furthermore, for example, a simple determination of the bearing force can be enabled independently of the orientation of a motor, for example on a bicycle frame of an electric bicycle. Based on the bearing force thus determined, further functions of the drive 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 an output shaft, a motor, at least one bearing by means of which the output shaft is mounted, at least one bearing force sensor, in particular two bearing force sensors, and a detection unit.The output shaft is configured for connection to cranks of a crank drive. For example, the crankshaft can therefore also be referred to as an output shaft. The motor is configured to generate a motor torque on the output shaft, which is intended to support a driver torque applied by a driver. A motor shaft of the motor is arranged coaxially to the output shaft. The bearing is provided for supporting the output shaft. In addition, each bearing force sensor is configured to detect a force. In particular, the two bearing force sensors are arranged at different circumferential positions relative to the output shaft. The detection unit is configured to detect a bearing force on the bearing based on the force detected by the bearing force sensor, in particular the forces detected by the bearing force sensors.

[0009] In particular, the bearing force is considered to be the total resulting force in the area of ​​the bearing, which occurs, for example, due to engine torque and / or driver torque. The detection unit is particularly preferably configured to determine a bearing force direction and a bearing force magnitude on the bearing based on the detected forces.

[0010] Preferably, each bearing force sensor is configured to detect a force, in particular exclusively, along a predetermined direction. Preferably, the two bearing force sensors are arranged in the axial direction of the output shaft at the level of the bearing. In other words, a drive arrangement is provided that has two force sensors on the bearing. Because the two bearing force sensors are arranged 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 of the instantaneous bearing force on the bearing.Preferably, this determination of the bearing force direction and the bearing force magnitude is carried out based on a previously known relative installation position of the two bearing force sensors to each other, and in particular based on previously known measuring directions of the bearing force sensors along which the respective forces are measured.

[0011] 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.

[0012] For a particularly simple design, the two force sensors can preferably be identical in construction.

[0013] The drive arrangement thus offers the advantage of measuring the bearing force at the bearing using a particularly simple, cost-effective, and space-saving design. The use of force sensors, which can be characterized, for example, by particularly simple and lightweight designs that require little installation space, also allows for a particularly space-saving arrangement. Furthermore, the use of force sensors, which generally have little or no susceptibility to magnetic fields, enables particularly reliable and precise measurement of the bearing force.

[0014] A further advantage of the drive arrangement is that the direction and magnitude of the bearing force can be precisely determined regardless of the installation position of the drive unit on an electric bicycle. This means that the drive unit can be arranged on the bicycle frame of an electric bicycle in any orientation, particularly with respect to rotation around the bottom bracket axis. Due to the circumferentially offset arrangement of the two force sensors, the resulting bearing force can be precisely measured in any orientation of the drive unit without the need to adapt the arrangement of the force sensors to the installation position. The resulting bearing force can preferably be determined based on a simple, one-time calibration of the system.

[0015] Due to the coaxial arrangement of the output shaft and motor shaft, the drive assembly also offers the advantage that the motor and output 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 output shaft. This arrangement has a particularly advantageous effect on the compact overall design of the drive assembly, for example, when the largest gear of the transmission is located on the output 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.

[0016] The subclaims contain preferred developments of the invention.

[0017] The drive arrangement preferably comprises two bearings for supporting the output shaft. This means that the output shaft is rotatably mounted by means of the two bearings. The output shaft has an output interface which is designed for connection to an output element. Such an output element can preferably be a chainring. Alternatively, another output element can preferably be provided which is designed for connection to a transmission element in order to enable torque to be transmitted from the output shaft to a drive wheel of the vehicle. The bearing force sensor is arranged in the axial direction of the output shaft at the level of the bearing arranged on the output side. In other words, a drive arrangement is provided which has the bearing force sensor in the region of the one of the two bearings which is arranged closer to the output element. The output interface is preferably connected to the output shaft in a rotationally fixed manner.In particular, the output shaft is constructed as a single piece. Bearing force measurement using the bearing force sensor offers the advantage of a particularly simple and cost-effective design for the output shaft, while still allowing for reliable determination of the forces used, for example, to operate the motor.

[0018] Particularly preferably, the drive assembly further comprises a bearing receptacle that at least partially surrounds the bearing in a ring-shaped manner. In particular, the bearing receptacle surrounds the bearing substantially completely, preferably except for a predetermined gap. The bearing receptacle is particularly designed to hold the bearing. For example, the bearing receptacle can be designed as a bearing shell.

[0019] 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 depending on the rider's torque.

[0020] 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.

[0021] 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.

[0022] The arrangement preferably further comprises a stop that limits movement of the bending beam in the radial direction. In particular, the stop limits the maximum deflection in the radial direction of a free end of the bending beam. This makes it possible to provide a particularly high level of mechanical robustness of the arrangement using a simple and cost-effective design. In particular, the stop can limit the deformability of the bending beam to a maximum extent. This can prevent, for example, damage to the bearing mount. In addition, robust and reliably precise positioning of the bearing by means of the bearing mount is ensured. Furthermore, the stop offers the advantage that the bending beam can be optimally designed for clear and easily detectable deformability in a specific bearing force range.For example, for particularly sensitive detection, the bending beam can be designed to be slightly deformable at low bearing forces, with the stop preventing excessive deformation.

[0023] Further preferably, the stop is arranged such that, in the unloaded state of the bearing, a predetermined air gap is formed between a free end of the bending beam and the stop. 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.

[0024] The drive arrangement preferably further comprises a transmission arranged between the motor and the output shaft. The transmission is designed to transmit torque between a motor shaft and the output shaft. The motor shaft is in particular an integral component of the motor. In particular, the transmission thus effects a transmission ratio between the motor and the output shaft. The output shaft is preferably a crankshaft of the vehicle, to which cranks of a crank drive can be connected. In particular, in this case, a pedal force applied by the driver of the vehicle using muscle power can be determined particularly reliably and directly at the output shaft. The transmission is preferably a spur gear transmission. The transmission is particularly preferably a two-stage transmission.The transmission preferably comprises an intermediate shaft which is parallel to the motor shaft and the output shaft, and wherein torque is transmitted between the motor shaft and the output shaft indirectly via the intermediate shaft and respective gear pairs between the respective shafts.

[0025] The transmission is preferably designed as a, preferably two-stage, spur gear transmission. This means that two spur gear stages are provided to provide a predetermined gear ratio between the output shaft and the crankshaft. This allows for optimal torque transmission of the drive unit for use in an electric bicycle with a compact design and simple construction. Such a spur gear transmission is characterized by a particularly high degree of efficiency, which ensures high efficiency in the operation of the drive assembly.

[0026] The transmission preferably has an intermediate shaft arranged parallel to the output shaft. This means that, in particular, an intermediate shaft axis of the intermediate shaft is arranged parallel to an output shaft axis of the output shaft. The transmission is designed to transmit torque between the output shaft and the motor shaft via the intermediate shaft. This means that the torque is transmitted from the motor shaft of the motor via the intermediate shaft to the output shaft. This allows the transmission to be provided with a predetermined gear ratio between the output shaft and motor shaft in a particularly simple manner and with few components. In addition, a gear ratio can be easily adjusted, for example, by scaling the intermediate shaft, in particular with corresponding gears.

[0027] Particularly preferably, the transmission comprises a first gear and a second gear. The first gear and the second gear are each connected to the intermediate shaft in a rotationally fixed manner. For example, the first gear, the second gear, and the intermediate shaft can be formed together as a single, integral component. This allows for a simple, cost-effective, and robust design.

[0028] The gear unit preferably has motor gearing formed on the motor shaft. In particular, a portion of the motor shaft is thus designed as a gear with the motor gearing. The first gear meshes with the motor gearing. This further advantageously facilitates a compact, simple, and cost-effective design.

[0029] Further preferably, the transmission comprises a third gearwheel which is rotatably connected to the output shaft. In particular, the third gearwheel can additionally be arranged to be rotatable relative to the output shaft in a freewheel mode. The third gearwheel is in engagement with the second gearwheel of the intermediate shaft. In particular, the third gearwheel can thus

[0030] Torque is transferred from the intermediate shaft to the output shaft.

[0031] Particularly preferably, the drive arrangement further comprises a freewheel between the motor shaft and the output shaft. Particularly preferably, the freewheel is arranged between the third gear and the crankshaft. In particular, the freewheel is designed to be able to switch between a rotationally fixed connection and a relatively freely rotatable connection between the third gear and the output shaft. Preferably, the freewheel locks in the drive direction of the motor and opens when the motor is stationary and during actuation of the cranks. Alternatively or additionally, the freewheel can be designed to be controllably actuated, for example by means of a control unit. In particular, the freewheel can thus be decoupled from the output shaft, for example to switch off the motor assistance, in particular when a predetermined speed of the vehicle is exceeded.

[0032] Particularly preferably, the motor is arranged on a side of the transmission facing the output interface. This means that the motor is arranged closer to the output element than the transmission in the axial direction of the output shaft. Alternatively, the motor is preferably arranged on a side of the transmission facing away from the output interface. This means that in this case, the transmission is arranged closer to the output interface than the motor. In other words, the motor can be arranged on the right or left with respect to a direction of travel of the vehicle, on which the drive arrangement can be arranged.

[0033] 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 be a housing of the motor, for example. By fixing the bearing receptacle to the housing, a precise and, in particular, immovable mounting of the bearing relative to the housing is provided. The fastening region can, for example, be a section of the bearing receptacle which, along the circumferential direction, corresponds to at least one-third, preferably at least half, and preferably a maximum of three-quarters, of the entire ring of the bearing receptacle. Preferably, the fastening region 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 receptacle.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 to provide a particularly robust fixation.

[0034] 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.

[0035] 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 mount, in a recess in the housing. The recess preferably has an internal geometry that corresponds to an external geometry of the fastening element. This enables a 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.

[0036] Preferably, the fastening region is formed as at least part of an outer circumference of the bearing receptacle. This means that, in particular, the bearing receptacle is fixed to the housing in that the outer circumference of the bearing receptacle is at least partially fixed directly to the housing, preferably by means of a press connection between the outer circumference and the housing. This makes it possible to provide a particularly simple, lightweight, and cost-effective design of the arrangement. In addition, a particularly high positional accuracy of the bearing receptacle and thus of the bearing can be provided because, for example, the recess in the housing can be manufactured in a simple and cost-effective manner with high precision. This is particularly advantageous if the housing is a deep-drawn component, preferably a sheet metal housing in which the recess is produced by deep-drawing.

[0037] 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 from the preferably circular outer contour of the fastening element by the predetermined gap. The gap is preferably a maximum of 0.5 mm, preferably a maximum of 0.2 mm, particularly 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 requiring a separate component for the stop. This allows for a particularly simple and cost-effective design with few components.Preferably, a stop area is provided at the free end of the bending beam, with the gap dimension being provided between the stop area and the housing. Preferably, a gap that is larger than the gap dimension exists between a remaining area of ​​the bending beam and the recess, so that, in particular, free movement of the bending beam is possible, and the bending beam rests exclusively on the stop area.

[0038] 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.

[0039] 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. 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 positional change of a portion of the bending beam relative to another component, such as the housing, can be directly detected in a simple and particularly precise manner.

[0040] The drive arrangement preferably further comprises a crank mechanism with cranks. The cranks are connected, in particular in a rotationally fixed manner, to the output shaft or are fixed to the output shaft. Using the cranks, the rider can apply a pedaling force using muscle power, which creates a pedaling torque on the output shaft.

[0041] 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.

[0042] Furthermore, the invention relates to a method for operating the drive arrangement described above. The method comprises the following steps:

[0043] - Determination of forces using the two bearing force sensors, and

[0044] - Determining a bearing force on the bearing based on the forces detected by the bearing force sensors. This method is characterized by its particularly simple and cost-effective implementation, allowing precise results for the bearing force on the bearing to be determined.

[0045] The method preferably further comprises the step of determining an output force on the output element based on, in particular, the bearing force direction and the bearing force magnitude. The output force is considered to be a force exerted by a transmission element, such as a bicycle chain, on the output element, in particular during operation of the electric bicycle. The output force is preferably present on an outer circumference of the chainring and in a predetermined direction along which the bicycle chain extends, for example, to a rear wheel. The output force is preferably additionally determined based on previously known geometric properties of the drive arrangement, in particular of the chainring.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.

[0046] 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.

[0047] 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.

[0048] Short description of the drawings

[0049] 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:

[0050] Figure 1 is a simplified schematic view of an electric bicycle with a drive arrangement according to a first embodiment of the invention,

[0051] Figure 2 is a sectional view of the drive arrangement of Figure 1,

[0052] Figure 3 is a simplified detailed sectional view of the drive arrangement of Figure 1 to illustrate the mode of operation,

[0053] Figure 4 is a perspective detailed view of the drive arrangement of Figure 1,

[0054] Figure 5 shows a further detailed view of the drive arrangement of Figure 1,

[0055] Figure 6 is a further detailed view of the drive arrangement of Figure 1, and

[0056] Figure 7 is a sectional view of a drive arrangement according to a second embodiment of the invention.

[0057] Preferred embodiments of the invention

[0058] Figure 1 shows a simplified schematic view of an electric bicycle 100 with a drive assembly 1 according to a first exemplary 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 exemplary embodiment are shown in Figures 3 to 5. The drive assembly 1 has a crank drive 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.

[0059] In addition, the crank drive 2 comprises an output shaft 22, which is connected in a rotationally fixed manner to the cranks 21, and two bearings 23, 24 for the rotatable mounting of the output shaft 22.

[0060] The drive arrangement 1 further comprises an output element 3, which is a chainring, and which is connected in a rotationally fixed manner to an output interface 35 of the output shaft 22, and a bicycle chain 107 as a transmission element, which is in engagement with the chainring 3.

[0061] In order to support the driver torque with an additional engine torque, the drive arrangement 1 comprises a motor 4, preferably an electric motor, which is supplied with electrical energy in particular by an electrical energy storage device (not shown) and which is designed to generate the engine torque.

[0062] The drive assembly 1 is preferably attached to a bicycle frame 101 of the electric bicycle 100 by means of a housing 40.

[0063] The output shaft 22 is mounted in the housing 40 by means of the two bearings 23, 24. The housing 40 has a bearing collar 43 on the bearing 23 facing away from the output shaft, within which the bearing 23 is arranged (see Figure 2). In particular, the bearing collar 43 is an integral part of the housing 40.

[0064] In addition, the drive arrangement 1 comprises a transmission 8. The transmission 8 is designed to transmit torque between a motor shaft 42 of the motor 4 and the output shaft 22.

[0065] The transmission 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 output 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.

[0066] 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.

[0067] In the drive assembly 1, the motor shaft 42 of the motor 4 and the output shaft 22 are arranged coaxially with each other. This means that the motor shaft 42 and the output 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 output shaft 22 extends through the motor shaft 42.

[0068] Output shaft 22 and motor shaft 42 are rotatably mounted relative to each other by means of bearings 48.

[0069] The motor shaft 42 of the motor 4 protrudes 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 comprises a second gear 82, which is also connected in a rotationally fixed manner 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. Furthermore, the transmission 8 comprises a third gear 83, which is arranged to rotate about the pedal axis 22a. A freewheel 89 is located between the third gear 83 and the output shaft 22, which enables either a rotationally fixed connection or a freely rotatable arrangement of the third gear 83 and the output shaft 22 relative to one another.

[0072] 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 output shaft 22.

[0073] 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 output 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 output 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 output shaft 22, a particularly small extension of the other parts of the drive arrangement 1 in the radial direction with respect to the pedal axis 22a is possible, since the remaining gear volume extends only slightly out of an axial projection surface of the motor 4.

[0074] Between the rotor 4 and the gear 8, there 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 gear with respect to the direction of the pedal axis 22a.

[0075] 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. 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 bearing 24, as described below.

[0076] 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 to 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 bearing 24.

[0077] 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.

[0078] 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 bearing 24.

[0079] 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 output shaft 22 at the level of the output-side bearing 24. 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 mechanical expansion and / or compression, along exactly one predetermined direction, namely in the radial direction with respect to the pedal axis 22a.

[0080] 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.

[0081] 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.

[0082] Figure 4 shows a perspective view of the bearing holder 5.

[0083] The bearing 24 is arranged in a recess of the bearing holder 5, wherein in the unloaded state preferably substantially the entire inner circumference of the bearing holder 5 is in contact with an outer circumference of the bearing 24.

[0084] The bearing holder 5 is also slotted, with a slot 57 which extends completely through the entire bearing holder 5 in the radial direction.

[0085] 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.

[0086] 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 output shaft 22 (not shown in Figure 6) protrudes completely through the recess 65 of the housing 4.

[0087] 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.

[0088] 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 gap is provided between the flexural beams 53 of the bearing support 5 and the fastening element 50a to ensure unhindered mobility of the flexural beams 53.

[0089] The fastening element 50a has an outer diameter corresponding to the inner diameter of the recess 65.

[0090] 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 to the housing 40 of the motor 4.

[0091] 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.

[0092] On the radially outer side of each bending beam 53 there is a flattened portion 41 on which the respective bearing force sensor 51, 52 is arranged. The bearing mount 5 is designed and fixed to the fastening element 50a 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 50a and thus also 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 bearing against the inner circumference of the recess 65. This makes it possible to provide a particularly simple and lightweight design for the drive arrangement 1.In addition, it is particularly easy and cost-effective to produce.

[0093] If the crank mechanism 2 is loaded by the rider's pedaling force, this causes a bearing force 59 on the bearing 24. Since the bearing 24 is held in the housing 40 of the motor 4 by the bearing support 5, this bearing force 59 has a corresponding effect on the bearing support 5. Due to the special design of the bearing support 5 with the movable bending beams 53, the bearing force 59 leads to a deflection of the bending beams 53 in the radial direction. This deformation can be detected by the bearing force sensors 51, 52, which are designed as strain gauges.

[0094] 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.

[0095] The free movement of the bending beams 53 in the radial direction enables particularly sensitive detection with appropriate mechanical design. This means, for example, by appropriately designing the thicknesses of the bending beams 53 in the axial and / or radial direction, it is possible to ensure that a clearly measurable deformation occurs even with small bearing forces. In particular, this enables the detection of low torques applied by the driver with high accuracy. To ensure particularly high accuracy by ensuring the deformation of the bending beams 53 is as unaffected as possible, the bending beams 53 are spaced apart in the axial direction from the fastening element 50a, against which the fastening area 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 fastening element 50a and the fastening element 50a, against which the end face 50a of the fastening region 50 abuts. As a result, the deformation of the bending beam 53 is not influenced by friction, for example.

[0096] Furthermore, the bending beams 53 and / or the bearing 24 can be designed such that a region with the lowest possible friction is formed between the radially inner side of the bending beams 53 and the radially outer side of the bearing 24, so that, for example, a falsification of the measurement results due to stresses caused by static friction can be avoided or reduced.

[0097] Furthermore, the drive assembly 1 includes 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 the extension of the slot 57.

[0098] 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.

[0099] 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.

[0100] For this purpose, a one-time calibration of the drive assembly 1 is carried out.

[0101] During calibration, no motor torque is generated by the motor 4. During calibration, in a first step, the crank drive 2 can be arranged so that the cranks 21 are aligned horizontally. In this first calibration configuration, exactly one crank 21, namely the crank 21 pointing forward in the direction of travel, is actuated with 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 from the actuating force and the output force 60.

[0102] 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 direction 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.

[0103] Based on the forces 55, 56 of the bearing force sensors 51, 52 recorded in both calibration steps, the ratio of the two forces 55, 56 can be used to determine the orientation of the bearing force sensors 51, 52 relative to the previously known positions of the cranks 21 and / or the bicycle chain 107. This also allows the orientation of the drive unit 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.

[0104] 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 gearbox 8 and the output interface 35. In detail, the motor 4 is arranged between the output-side bearing 24 and the first gear 81 of the gearbox 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.

Claims

Claims 1 . Drive arrangement of a vehicle (100) operable with muscle power and / or motor power, in particular an electric bicycle, comprising: - an output shaft (22) which is arranged to be connected to cranks (21) of a crank drive (2), - a motor (4) which is arranged to generate a motor torque to support a driver torque applied by a driver on the output shaft (22), - wherein a motor shaft (42) of the motor (4) is arranged coaxially to the output shaft (22), - at least one bearing (24) by means of which the output shaft (22) is mounted, - at least one bearing force sensor (51, 52), in particular two bearing force sensors (51, 52), - wherein the bearing force sensor (51, 52) is arranged to detect a force (55, 56), and - a detection unit (6) which is configured to detect a bearing force (59) on the bearing (24) based on the force (55, 56) detected by the bearing force sensor (51, 52).

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

3. Drive arrangement according to one of the preceding claims, - comprising two bearings (23, 24) for supporting the output shaft (22), - wherein the output shaft (22) has an output interface (35) which is designed to be connected to an output element (3), and - wherein the bearing force sensor (51) is arranged in the axial direction of the output shaft (22) at the level of the bearing (24) arranged on the output side.

4. Drive arrangement according to one of the preceding claims, further comprising a bearing receptacle (5) which at least partially surrounds the bearing (24) in an annular manner.

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 bearing (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 gear (8) which is arranged between the motor (4) and the output shaft (22) and arranged to transmit torque between the motor shaft (42) and the output shaft (22).

11. Drive arrangement according to claim 10, wherein the transmission (8) is designed as a, in particular two-stage, spur gear transmission.

12. Drive arrangement according to claim 10 or 11, wherein the transmission (8) has an intermediate shaft (85) which is arranged parallel to the output shaft (22), and wherein the transmission (8) is arranged for torque transmission between the motor shaft (42) and the output shaft (22) via the intermediate shaft (85).

13. Drive arrangement according to one of claims 10 to 12, - wherein the transmission (8) comprises a first gear (81) and a second gear (82), wherein the first gear (81) and the second gear (82) are connected in a rotationally fixed manner to the intermediate shaft (85), - in particular, wherein the gear (8) has a motor toothing (84) formed on the motor shaft (42), and wherein the first gear (81) is in engagement with the motor toothing (84), - in particular wherein the transmission (8) has a third gear (83) which can be connected in a rotationally fixed manner to the output shaft (82), and wherein the third gear (83) is in engagement with the second gear (82).

14. Drive arrangement according to one of claims 10 to 13, further comprising a freewheel (89) between the motor shaft (42) and the output shaft (22) 15. Drive arrangement according to one of claims 10 to 14, wherein the motor (4) is arranged on a side of the transmission (8) facing away from the output interface (35), or wherein the motor (4) is arranged on a side of the transmission (8) facing the output interface (35).

16. 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.

17. Drive arrangement according to one of the preceding claims, further comprising a crank drive (2) with cranks (21), wherein the cranks (21) are connected to the output shaft (22).

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

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

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

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

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