Drive device for a human-powered bicycle with an electric auxiliary drive and method for controlling the drive device

Abstract

The invention relates to a drive device for a muscle-powered bicycle with an auxiliary electric drive (2), comprising a drive unit (1) with a bottom bracket gear (3) that can be switched by a switching device (6) and can be subjected to a respective drive torque both by at least one pedal crank (5) operatively connected to a pedal crankshaft (4) and by the auxiliary drive (2), further comprising a sensor system (7) for detecting drive-specific state variables of the drive unit (1), wherein the sensor data of the sensor system (7) can be transmitted to an evaluation and control device (8) that is designed to receive a switching command and to determine an optimal switching time based on the detected drive-specific state variables and to control the switching device (6) depending on the optimal switching time.Furthermore, the invention relates to a method for controlling the drive device and to a bicycle with such a drive device.

Description

[0001] The invention relates to a drive device for a human-powered bicycle with an electric auxiliary drive, as well as a method for controlling such a drive device. A further claim is directed to a bicycle with the aforementioned drive device.

[0002] For example, EP 2 862 788 A1 discloses a control unit for use in a bicycle propelled by a rider. The bicycle comprises an electric drive unit, a mechanical drive unit operable by muscle power, and at least one transmission shiftable by at least one shifting means. The control unit is designed to control the shifting means and the electric drive unit. The shiftable transmission is designed to convert a first torque applied by the rider to the mechanical drive unit into a second torque. The bicycle is movable under the action of the second torque and a third torque applied by the electric drive unit.

[0003] A generic drive device for a muscle-powered bicycle with an auxiliary electric drive is known in the prior art from DE 10 2011 120 675 B4. Another drive device for a muscle-powered bicycle with an auxiliary electric drive according to the prior art is disclosed in EP 2 684 791 A1.

[0004] The object of the present invention is to propose a drive device for a human-powered bicycle with an auxiliary drive that implements a component-friendly shifting process. This object is achieved by the subject matter of the independent patent claims. Advantageous embodiments are the subject matter of the subclaims, the following description, and the figure.

[0005] A drive device according to the invention for a muscle-powered bicycle with an electric auxiliary drive comprises a drive unit with a bottom bracket gear that can be switched by a switching device and can be subjected to a respective drive torque both by at least one pedal crank operatively connected to a pedal crankshaft and by the electric auxiliary drive, further comprising a sensor system for detecting drive-specific state variables of the drive unit, wherein the sensor data of the sensor system can be transmitted to an evaluation and control device that is designed to receive a switching command and to determine an optimal switching time based on the detected drive-specific state variables and to control the switching device depending on the optimal switching time.

[0006] The drive device is thus designed in particular as a mid-engine drive, wherein the sum of the first drive torque mechanically introduced via the pedal crankshaft and the second drive torque introduced by means of the electric auxiliary drive results in a total drive torque, which is transmitted via the pedal crank gear, for example via a pinion and a drive chain, to at least one rear wheel of the bicycle in order to move the bicycle accordingly. The total drive torque thus consists of a drive torque mechanically introduced by muscle power and a motor torque of the electric auxiliary drive. The auxiliary drive is, for example, an electric drive or an electric machine that is powered by a power supply unit, e.g.A battery or accumulator is supplied with electrical energy, wherein the electric machine comprises a stator fixed to a housing and a rotor that can be driven in rotation relative to it. The input torque of the electric auxiliary drive is therefore the torque generated by the rotor, which is suitably introduced into the bottom bracket gear.

[0007] The sensor system for detecting the drive-specific state variables comprises one, preferably several sensors, which can be arranged on the switching device, on the auxiliary drive, on the bottom bracket gear, and / or on the pedal crank. The sensor(s) on the switching device can detect, in particular, the angular position of a shift drum of the switching device and / or the position of shift pawls operatively connected to the shift drum relative to the shift drum. However, it is also conceivable to detect the position of the shift drum without one or more sensors. It is possible to detect the shift drum position by approaching a zero point, for example an end stop. Upon reaching the end stop, a motor current of an actuator that causes the shift drum to rotate can increase, thereby setting a reference for determining a zero point for the shift drum.The increase in motor current is detected by the evaluation and control device.

[0008] The sensor(s) on the electric auxiliary drive can detect the drive or input torque of the auxiliary drive and / or the speed of the rotor or a shaft operatively connected to it. The sensor(s) on the bottom bracket gear can also detect the speed of the pedal crank driven by the cyclist's muscle power and / or the drive or input torque applied by the cyclist. In addition, an output torque or an output torque or the total drive torque at the bottom bracket gear can be detected. Furthermore, the sensor(s) can be arranged on at least one pedal crank of the bicycle in order to determine a crank position or a crank rotation angle of the respective pedal crank. Accordingly, the sensor system preferably comprises at least one position sensor, a rotation angle sensor, a displacement sensor, a torque sensor and / or a speed sensor.

[0009] Drive-specific state variables are preferably understood to mean a rotational speed of a drive shaft of the auxiliary drive and / or the pedal crankshaft, an input torque of the auxiliary drive and / or the pedal crankshaft, an output torque of the bottom bracket gear, a crank position of the respective pedal crank and / or a current gear stage of the bottom bracket gear, wherein these state variables can be detected by one of the aforementioned sensors or by a combination of several of the aforementioned sensors.

[0010] The pedal-crank mechanism can be shifted by means of the shifting device. A shifting command, which is sent as a command signal to the evaluation and control device, is received and evaluated by the evaluation and control device. As a result of the shifting command, an optimal shifting time of the shifting device is determined, and a shifting operation of the pedal-crank mechanism is implemented or executed accordingly by a corresponding command to the shifting device. In other words, the control of the shifting device consists, among other things, in carrying out a change from one gear to another, wherein the pedal-crank mechanism preferably comprises several gears.In this context, the respective gear stage is to be understood as a specific gear ratio of the pedal crank mechanism, whereby a gear change in a known manner changes from a gear stage with a first gear ratio to another gear stage with a higher or lower gear ratio.

[0011] The bicycle has means for transmitting the shifting command to the evaluation and control device. The drive device preferably comprises a switch which is designed to transmit the shifting command to the evaluation and control device through manual actuation. The shifting command is consequently sent from the switch to the evaluation and control device. On the handlebars of the bicycle, for example, there is an actuation option, by actuating which the shifting command can be generated and accordingly sent to the evaluation and control device. The switch can in particular be designed such that a desired gear can be selected as desired. In particular, it is conceivable that a next higher gear or a next lower gear can be selected via the shift command, or that several gears can be skipped.The switch can be designed as a push button, trigger or rotary lever, whereby other means for transmitting the switching command to the evaluation and control device are also conceivable.

[0012] Alternatively, automatic operation or at least (partially) automated operation of the bicycle is possible, wherein control electronics are provided for this purpose which are designed to monitor, for example, an input torque of the auxiliary drive and / or an input torque from the pedal crankshaft and to generate a switching command based on this information or data and to send this to the evaluation and control device.

[0013] As a result of the shift command, a gear change is initiated from a first gear stage with a first gear ratio of the bottom bracket gear to a second gear stage with a second gear ratio. Torque peaks can occur during gear changes, which can lead to significant wear and, consequently, a shorter service life of the drive-related components of the drive system. To reduce wear, the drive-specific state variables detected by the sensors are used to determine the optimal shifting point, ensuring gear changes are as load-free as possible.

[0014] For this purpose, for example, the exact position or angle of rotation of the respective crank or crankshaft is determined. Based on this geometric data and taking into account the available drive torque, the evaluation and control unit can determine the exact time or the exact shifting path for each gear, from which the gear change should be initiated using the shifting device. This allows for particularly low-wear shifting processes.

[0015] Each pedal crank can be rotated 360° or manually driven to drive the bicycle drive using muscle power. The pedal crank position is 0° when the first pedal crank protrudes vertically upwards from the pedal axis or the pedal crank shaft. At the same time, the second pedal crank is at a pedal crank position of 180° relative to the first pedal crank, in a known manner, i.e. when the second pedal crank protrudes vertically downwards from the pedal axis or the pedal crank shaft. At a respective pedal crank position of 0° or 180°, no torque can be transferred from the pedal cranks to the bottom bracket gear due to the lack of a lever arm. Therefore, there is no or only a minimal drive torque at the pedal crank gear resulting from muscle power.

[0016] When the bicycle moves forward, the cyclist presses the first pedal in such a way that the connected first crank pivots forward in the direction of travel due to the shear load exerted by the cyclist. When the crank is at a 90° position, i.e. when the first crank is aligned horizontally forward in the direction of travel, the lever arm is at its greatest, so that with constant pedaling force from the cyclist, a first maximum torque acts on the crank mechanism at the 90° crank position. At the same time, the second crank pivots backward from a crank position of 180° to a crank position of 270°, with a tensile load from the cyclist acting on the second crank, which generates a second maximum torque at the 270° crank position.The tensile load can be introduced particularly when the cyclist's legs are actively connected to the pedals of the cranks. This can be achieved, for example, by shoes that are firmly attached to the pedals. Thus, an optimal shifting moment can be achieved particularly when the cranks are in or at a crank position of 0° or 180° due to the low drive torque. In other words, an optimal shifting moment is achieved particularly when a gear change can be initiated and executed with particularly low load, ideally without load.

[0017] The shifting device preferably comprises a shift drum for setting a gear of the bottom bracket transmission. The shift drum is designed, in particular, to actuate one or more shift pawls that are pretensioned in the direction of the shift drum. For this purpose, the shift drum is, in particular, electrically controllable by the evaluation and control device or at least indirectly rotatably driven about its longitudinal axis by means of an actuator. Depending on the angle of rotation of the shift drum, one or more shift pawls are actuated such that a desired gear is set on the bottom bracket transmission or a gear change from one gear to another occurs.In the contact area with the respective shift pawls, the shift drum has an outer peripheral geometry that pushes the respective shift pawl away from the shift drum depending on the angle of rotation of the shift drum relative to the longitudinal axis or allows movement of the shift pawls toward the longitudinal axis by releasing the preload elements. In other words, the shift drum has projections and valleys distributed alternately around the circumference in the contact area with the respective shift pawl, along which the preloaded shift pawls slide when the shift drum is actuated or rotated.

[0018] The more pawls the shifting device has, the greater the number of possible gears or the different gear ratios of the bottom bracket gear. The shift drum is thus particularly designed to set a gear ratio of the bottom bracket gear. The required angle of rotation of the shift drum to actuate the pawls can be selected to be either the same or different. This is stored accordingly in the evaluation and control device and is therefore known. The sensors can also determine the angle of rotation of the shift drum. By determining the angle of rotation of the shift drum, information about the current gear can thus be obtained at least indirectly.Alternatively, it is conceivable that the switching device comprises a derailleur or hub gear for setting a gear stage of the bottom bracket gear, wherein the derailleur or hub gear is designed to be actuated electrically or mechanically, for example by a cable pull.

[0019] The evaluation and control device is preferably designed to control an input torque of the electric auxiliary drive. Controlling the input torque of the electric auxiliary drive means a motor intervention in which the input torque of the rotor is increased or reduced. In particular, during the gear shifting process, a counter-torque is generated on the drive side of the bottom bracket gear, which is advantageously as high as the muscle power torque on the pedal crankshaft. The bottom bracket gear is thus placed in a virtually load-free state so that the gear shifting process takes place as gently as possible. After receiving the gear shift command and before initiating the gear shifting process, the evaluation and control device is therefore able to adjust a drive torque of the electric auxiliary drive in order to make the gear shifting process as load-free as possible.

[0020] Preferably, the input torque of the electric auxiliary drive is reduced during the gear shifting process. Particularly when the pedal cranks are at a position of 0° or 180°, the input torque of the auxiliary drive can be further reduced before or during the gear shifting process. This makes the gear shifting process load-free. Furthermore, a time point for subsequently increasing the input torque of the electric auxiliary drive can be determined. In other words, a time point for renewed motor intervention of the auxiliary drive can be adjusted.

[0021] Furthermore, a negative input torque of the electric auxiliary drive is preferably generated during a gear shift. A negative input torque is understood to mean a drive torque that counteracts the drive torque from the pedal cranks, reducing the total drive torque. In other words, the drive torque from the auxiliary drive and the drive torque from the pedal cranks act in opposite directions. Such a procedure is particularly advantageous when an optimal gear shifting time is selected at a time when the pedal crank position is not essentially at 0° or 180°. Thus, the gear shifting process can be initiated in any crank position of the pedal cranks, and the gear shifting device can be controlled accordingly.In addition, the gear shifting process is designed to be particularly smooth for the cyclist, even though the gear shifting process takes place under load on the bottom bracket gear by the pedal crankshaft.

[0022] Alternatively, the evaluation and control device is designed to control an output torque of the bottom bracket gear. Controlling the output torque of the bottom bracket gear refers to a motor intervention in which the output torque on the bottom bracket gear is increased or reduced. In other words, an additional output torque can be generated in the direction of the muscle power torque introduced into the pedal crankshaft by muscle power in order to place the bottom bracket gear into a nearly load-free state by applying the output torque during the gear shifting process, so that the gear shifting process is as gentle as possible. The evaluation and control device is therefore able to adjust an output torque of the bottom bracket gear after receiving the gear shift command and before initiating the gear shifting process in order to make the gear shifting process as load-free as possible.

[0023] The sensor system provides the evaluation and control unit with the drive-specific state variables, from which the evaluation and control unit can determine which gear is currently engaged. Furthermore, based on the direction of rotation of the respective rotating components, it can determine which gear should be engaged next and at what time. In other words, the evaluation and control unit is designed to carry out the motor intervention of the auxiliary drive and / or the shifting process of the shifting device on a gear-step-by-step basis. The gear-step information determined by the evaluation and control unit therefore enables the electrification and automation of the shifting of the bottom bracket gear. Furthermore, the evaluation and control unit can not only determine the optimal shifting time, but can also delay or accelerate the shifting process.Furthermore, over the service life of the device, the wear of, for example, shift claws, roller freewheels, shift cables of the drive device can be determined by the evaluation and control device and the switching processes can thus be designed accordingly.

[0024] The evaluation and control unit is designed to store sensor data from the sensor system and compare it with newly acquired sensor data. By storing the sensor data, the evaluation and control unit can be trained to learn. Newly acquired sensor data on drive-specific state variables are compared with sensor data already stored in a database or stored in a database that was used for a specific shift of the bottom bracket gear system, in order to select an optimal shifting point based on this data. In this case, redetermining the optimal shifting point is no longer necessary; instead, the optimal shifting point can be selected directly for recurring drive situations.

[0025] Preferably, the evaluation and control device is configured to replace the stored sensor data of the sensor system with the newly acquired sensor data. Previously stored sensor data can thus be replaced by newly acquired sensor data on the drive-specific state variables in order to be able to retain current data, which, for example, takes wear on the drive device into account, for determining the optimal switching time.

[0026] An output unit can be mounted on the bicycle handlebars, which can provide the cyclist with specific drive-related information in a suitable manner, particularly visually. Acoustic and / or haptic feedback is also conceivable. For example, the cyclist can be informed of the current gear position or ratio, the efficiency of the bottom bracket gear, and / or the drive efficiency. Other input and output-related variables can also be output from the output unit.

[0027] According to a method according to the invention for controlling a drive device, wherein the drive device comprises a drive unit with a bottom bracket gear that can be switched by a switching device and an electric auxiliary drive, wherein the bottom bracket gear can be subjected to a respective drive torque both by at least one pedal crank operatively connected to a pedal crankshaft and by the electric auxiliary drive, drive-specific state variables of the drive unit are detected by means of a sensor system, wherein the sensor data of the sensor system are transmitted to an evaluation and control device, wherein a switching command is received by the evaluation and control device, wherein an optimal switching time of the bottom bracket gear is determined on the basis of the detected drive-specific state variables, and wherein the switching device is controlled as a function of the determined optimal switching time.Control of the shifting device means that a shifting operation is initiated and executed at the optimal shifting time, shifting between a first gear and a second gear. The shifting device preferably comprises several gears, and shifting can be carried out at will between the gears, which comprise different gear ratios.

[0028] A bicycle according to the invention comprises a drive device of the type described above. Such a bicycle is understood to be, in particular, a pedelec or an S-pedelec with at least one rear wheel and at least one front wheel, in which the muscular drive of the pedelec or S-pedelec is at least partially assisted by an electric auxiliary drive to relieve the cyclist. Complete takeover of the bicycle drive by the auxiliary drive is also possible, at least temporarily.

[0029] The above definitions as well as explanations of technical effects, advantages and advantageous embodiments of the device also apply mutatis mutandis to the method according to the invention and to the bicycle according to the invention.

[0030] An exemplary embodiment of the invention is explained in more detail below with reference to the single schematic drawing, wherein identical or similar elements are provided with the same reference numerals. The single figure shows a schematic representation of a drive device according to the invention.

[0031] According to the single figure, a drive device for a bicycle (not shown here) comprises a drive unit 1 with a bottom bracket gear 3 switchable by a switching device 6 and an electric auxiliary drive 2. The auxiliary drive 2 is designed, for example, as an electric machine with a stationary stator (not shown here) and a rotor (also not shown here) that can be driven in rotation relative thereto. The rotor is operatively connected to the bottom bracket gear 3 via a shaft 13. The electric auxiliary drive 2 is connected to a battery (not shown here), which supplies the auxiliary drive 2 with electrical energy.

[0032] The shifting device 6 essentially consists of a shift drum 9 for setting a gear stage of the bottom bracket gear 3. The shifting device 6 can comprise a plurality of shift pawls (not shown here) preloaded in the direction of the shift drum 9, which are operatively connected to the shift drum 9 in such a way that, by actuation, i.e., by rotation of the shift drum 9, one or more shift pawls are actuated to at least indirectly set a gear ratio of the bottom bracket gear 3. In other words, switching between the gear stages takes place via the shift pawls, with each gear stage setting a respective gear ratio of the bottom bracket gear 3.

[0033] The bottom bracket gear 3 can be subjected to a respective drive torque by two pedal cranks 5 operatively connected to a pedal crankshaft 4, i.e., essentially by muscle power, as well as by the electric auxiliary drive 2. In the present case, only one pedal crank 5 is shown, with the second pedal crank being offset by 180° relative to the pedal crankshaft 4 in a known manner. In other words, the first pedal crank 5 is at a pedal crank position of 90° when the other pedal crank—not shown here—is at a pedal crank position of 270°. When the cyclist pedals the pedals 12 operatively connected to the pedal cranks 5, the muscle power-dependent drive torque is introduced into the bottom bracket gear 3 via the pedal crankshaft 4, which is rotationally fixedly connected to the pedals and spatially arranged between them.

[0034] The drive unit 1 includes a sensor system 7 comprising a plurality of sensors 11a, 11b, 11c, 11d configured as position sensors, displacement sensors, angle sensors, torque sensors, and / or speed sensors. The sensor system 7 is designed to detect drive-specific state variables of the drive unit 1. Such state variables include, for example, a rotational speed of a drive shaft of the electric auxiliary drive 2 and / or the pedal crankshaft 4, an input torque of the electric auxiliary drive 2 and / or the pedal crankshaft 4, a crank position of the respective pedal crank 5, and / or a current gear stage of the bottom bracket gear 3.

[0035] The sensor data from sensor system 7 is transmitted to an evaluation and control device 8, which is also supplied with electrical energy from the battery. The evaluation and control device 8 is configured to receive a switching command sent by a switch 10 and, as a result of the switching command, to determine an optimal switching time for the switching device 6 or the bottom bracket gear 3 based on the received and detected drive-specific state variables and to control the switching device 6 and thereby the drive unit 1 depending on the optimal switching time. The switch 10 is arranged, for example, on a handlebar of the bicycle (not shown) and can be operated manually by the cyclist, e.g., by pressing it, in order to send the switching command to the evaluation and control device 8 in a suitable manner.Alternatively, it is conceivable to design the switch as a trigger or as a rotary handle, by the actuation of which the switching command is transmitted to the evaluation and control device 8.

[0036] The sensor data acquired by the sensor system 7 can be stored on the evaluation and control device 8. Furthermore, the new sensor data can be compared with previously stored or saved sensor data, whereby the stored sensor data can be replaced if the data has changed, for example, due to wear or other circumstances.

[0037] An optimal shift point is defined as the point in time at which a shift from a first gear to a second gear occurs essentially without load. A first gear can be any gear, with the second gear in this context being a different gear from the first gear. In other words, a gear change involves a gear ratio change in the transmission.

[0038] The shifting process can be initiated and carried out, for example, when the pedal cranks 5 are in a pedal crank position of substantially 0° or 180°, respectively. In these pedal crank positions, no drive torque is introduced into the bottom bracket gear 3 due to the lack of a lever arm. In the pedal crank position of substantially 0° or 180°, i.e., at a respective torque dead center, the evaluation and control device 8 can further control an input torque of the electric auxiliary drive 2 or the drive torque of the auxiliary drive 2 upon initiation of the shifting process. In this case, the drive torque of the auxiliary drive 2 is reduced in order to enable a load-free shifting process of the bottom bracket gear 3. In other words, in this situation, no drive torque is transmitted to the bottom bracket gear 3 from either the bottom bracket spindle 4 or the auxiliary drive 2.A load-free shifting operation reduces wear on the components of the drive unit 1 used for the drive. Depending on the duration of the shifting operation, the shifting operation can be initiated by the respective pedal crank 5 shortly before reaching the dead center and / or terminated shortly after reaching the dead center. Following the shifting operation of the shifting device 6, a new motor intervention can be initiated by the electric auxiliary drive 2, or the drive torque of the auxiliary drive 2 can be increased back to its original level.

[0039] If the first pedal crank 5 is in a pedal crank position between 0° and 180° and accordingly the second pedal crank is in a pedal crank position between 180° and 360°, the evaluation and control unit 8 is further configured to generate a negative input torque of the electric auxiliary drive 2 during a gear shift in order to place the bottom bracket gear 3 into a load-free state during the gear shift. Depending on the arrangement, it is also conceivable to generate a positive output torque at the bottom bracket gear. In other words, the evaluation and control unit 8 determines an optimal gear shifting time while the cyclist transfers a drive torque to the bottom bracket gear 3 by pedaling. This means that in a pedal crank position deviating from 0° or 180°, a drive torque is introduced by the cyclist from the pedal crank shaft 4 into the bottom bracket gear 3.A gear shift can occur in this pedal crank position, particularly without load, if the auxiliary drive 2 is controlled by the evaluation and control device 8 in such a way that the auxiliary drive 2 generates a second drive torque that opposes the first drive torque of the pedal crankshaft 4, the two drive torques thereby essentially canceling each other out, so that a smooth and low-wear gear shift of the shift drum 9 is achieved even when the pedal crankshaft 4 is under load. Following the gear shift of the gear shift device 6, a new motor intervention by the electric auxiliary drive 2 can be initiated, or the drive torque of the auxiliary drive 2 is switched back in the positive direction and increased to its original level.

[0040] To enable a low-wear or load-free shifting process according to the previous examples, the drive-specific state variables are detected by means of the sensor system 7 and transmitted to the evaluation and control device 8. The first sensor 11a on the electric auxiliary drive 2 can detect the drive or input torque of the auxiliary drive 2 and / or the speed of the rotor or a shaft 13 operatively connected thereto, which in turn can transmit a torque and a speed to the bottom bracket gear 3. The second sensor 11b on the shifting device 6 can detect, in particular, the angular position of the shift drum 9 and / or the position of shift pawls (not shown here) relative to the shift drum 9.The third sensor 11c on the bottom bracket gear 3 can also detect the rotational speed of the pedal crankshaft 4, which is driven by the cyclist's muscle power, and / or the drive or input torque applied by the cyclist. Furthermore, the sensor system 7 can at least indirectly detect an output torque or the total drive torque at the bottom bracket gear 3. Furthermore, the fourth sensor 11d is arranged on the pedal crank 5 of the bicycle to determine the pedal crank position or a crank rotation angle of the respective pedal crank 5.

[0041] Based on the sensor data, the evaluation and control device 8 determines the optimal shifting time, i.e., the optimal time for actuating or rotating the shift drum 9 by a specific angle, which is selected such that the pawls of the shifting device 6 are actuated accordingly to shift the bottom bracket transmission 3 from a first gear to a second gear or from a first gear ratio to a second gear ratio. This optimal shifting time can, as previously described, occur at any desired pedal crank position of the pedal cranks 5. Reference symbol 1 drive unit 2 auxiliary drive 3 bottom bracket gears 4 crankshaft 5 cranks 6 Switching device 7 Sensor technology 8 Evaluation and control device 9 Shift drum 10 switches 11a First sensor 11b Second sensor 11c Third sensor 11d Fourth sensor 12 Pedal 13 Wave

Claims

[1] Drive device for a muscle-powered bicycle with an electric auxiliary drive (2), comprising a drive unit (1) with a bottom bracket gear (3) which can be switched by a switching device (6) and which can be subjected to a respective drive torque both by at least one pedal crank (5) operatively connected to a pedal crankshaft (4) and by the electric auxiliary drive (2), further comprising a sensor system (7) for detecting drive-specific state variables of the drive unit (1), wherein the sensor data of the sensor system (7) can be transmitted to an evaluation and control device (8), characterized byin that the evaluation and control device (8) is designed to receive a switching command and to determine an optimal switching time on the basis of the detected drive-specific state variables and to control the switching device (6) as a function of the optimal switching time, wherein the evaluation and control device (8) is designed to store sensor data of the sensor system (7) and to compare this with newly detected sensor data. [2] Device according to claim 1, characterized by that the switching device comprises a switching drum (9) for setting a gear stage of the bottom bracket transmission (3). [3] Device according to one of the preceding claims, characterized by that the sensor system (7) comprises at least one position sensor, one displacement sensor and / or one rotation angle sensor. [4] Device according to one of the preceding claims, characterized bythat the sensor system (7) comprises at least one torque sensor and / or one speed sensor. [5] Device according to claim 1, characterized by that the evaluation and control device (8) is designed to replace the stored sensor data of the sensor system (7) with the newly acquired sensor data. [6] Device according to one of the preceding claims, characterized by a switch (10) which is designed to transmit the switching command to the evaluation and control device (8) by manual actuation. [7] Device according to one of the preceding claims, characterized by that the evaluation and control device (8) is designed to control an input torque of the electric auxiliary drive (2). [8] Device according to one of claims 1 to 7, characterized by that the evaluation and control device (8) is designed to control an output torque of the bottom bracket gear (3). [9] Method for controlling a drive device according to one of claims 1 to 8, wherein the drive device comprises a drive unit (1) with a bottom bracket gear (3) switchable by a switching device (6) and an electric auxiliary drive (2), wherein the bottom bracket gear (3) can be subjected to a respective drive torque both by at least one pedal crank (5) operatively connected to a pedal crank shaft (4) and by the electric auxiliary drive (2), comprising the steps: - detecting drive-specific state variables of the drive unit (1) by means of a sensor system (7), - transmitting the sensor data of the sensor system (7) to an evaluation and control device (8), - Receiving a switching command by the evaluation and control device (8), - Determination of an optimal switching time of the bottom bracket gear (3) based on the recorded drive-specific state variables, and - Control of the switching device (6) depending on the determined optimal switching time. [10] Method according to claim 9, characterized by that the drive-specific state variables include a rotational speed of a drive shaft of the electric auxiliary drive (2) and / or the pedal crankshaft (4), an input torque of the electric auxiliary drive (2) and / or the pedal crankshaft (4), an output torque of the bottom bracket gear (3), a crank position of the respective pedal crank (5) and / or a current gear stage of the bottom bracket gear (3). [11] Method according to one of claims 9 or 10, characterized by that an input torque of the electric auxiliary drive (2) is reduced during a switching operation or that a negative input torque of the electric auxiliary drive (2) is generated during a switching operation. [12] Method according to one of claims 9 to 11, characterized bythat a positive output torque of the bottom bracket gear (3) is generated during a gear shift. [13] Method according to one of claims 9 to 12, characterized by that the switching command is sent from a switch (10) to the evaluation and control device (8). [14] Bicycle comprising a drive device according to any one of claims 1 to 8.

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