Drive unit, vehicle drivable by muscle power, and method for actuating a drive unit

Abstract

A drive unit (20) for a vehicle, in particular for a bicycle (10) driven by muscle power, having a transmission arrangement (16, 22) for setting up a plurality of gear stages, in which a form-fitting connection of two transmission elements is in each case set up, wherein the transmission arrangement (16, 22) has an input shaft (30), which is connectable to drive cranks, and an output shaft (34, 36), which can be coupled to an output (36), and having a control device (48, 88) for carrying out gear changes, characterized in that the control device (44, 88) is set up to carry out the following steps: receiving a gear-changing request to a target gear stage, calculating an optimum starting condition of the changing operation (P2, T2), and starting the changing operation when the optimum starting condition is met such that the form-fitting connection of the target gear stage is set up at an optimum time (T1, T2).

Description

[0001] Drive unit, vehicle propelled by muscle power and method for controlling a drive unit

[0002] The present invention relates to a drive unit for a vehicle, in particular for a vehicle that can be driven by muscle power, such as a bicycle, having a gear arrangement for establishing a plurality of gear stages, in each of which a positive connection between two gear elements is established, wherein the gear arrangement has an input shaft that can be connected to drive cranks and an output shaft that can be coupled to an output, and having a control device for carrying out gear changes.

[0003] Furthermore, the present invention relates to a vehicle that can be driven by muscle power and has such a drive unit, as well as to a method for controlling such a drive unit by means of the control device.

[0004] Human-powered vehicles, especially human-powered bicycles, often have gearshifts that define multiple gear ratios. These typically include three-speed hubs, derailleur gears, but also transmission arrangements designed as countershaft transmissions, in which shiftable spur gear sets are assigned to the majority of gear ratios.

[0005] Gear shifts in this type of gearshift are generally performed manually, for example, using a lever on the vehicle's handlebar. However, it is also known to support such gear shifts with a shift actuator. In this case, gear shift requests are usually initiated by pressing electronic buttons or switches connected to a control unit. The control unit then typically serves to actuate the shift actuator, which often includes a shift motor.

[0006] In the field of human-powered vehicles, it is also known to support the torque applied by a driver of the vehicle with a drive motor. The drive motor is usually an electric motor. Such bicycles are often referred to as "e-bikes" or "pedelecs." This type of vehicle also has a control device that appropriately adjusts the motor drive torque provided by the drive motor, which is usually provided in addition to the muscle-powered drive torque. As a rule, the adjustment is made such that the motor drive torque provided by the electric motor is adjusted depending on the torque applied by muscle power.Vehicles equipped with such a drive motor also generally have gearshifts, although fewer gear steps and / or a narrower range of available gear steps is often required. The gearshifts used for this purpose (usually derailleur gears or the aforementioned spur gears) are conventionally operated by the force of an operator.

[0007] From document DE 10 2012 107 939 B4, a bicycle drive device is known that includes a bicycle transmission configured as an internal gear and an electric drive-assist motor. A power control section controls the power of the drive-assist motor. A feasibility determination section determines whether a gear shift operation is feasible by querying whether an output condition of a bicycle crankset satisfies a gear shift permission condition. Upon receiving a gear shift command, a gear shift control section instructs the power control section to stop or reduce the power of the electric drive-assist motor if the vehicle speed is not zero.Further, the gearshift control section instructs the transmission to perform the gearshift operation when the feasibility determination section has determined that the gearshift permission condition is met, namely when the speed of the bicycle is zero. The transmission includes a gearshift motor controlled by the gearshift control section.

[0008] The output condition of the bicycle crankset that satisfies the gear shifting permitting condition may be a detected position of the bicycle crankset, a detected transmission torque of the gearbox, or a detected rear wheel torque. Furthermore, the output condition may be based on a detected torque of a crank axle of the bicycle crankset. Generally, the gear shifting permitting condition should be satisfied when a crank arm is within a range of 20° from a top and / or bottom dead center of the bicycle crankset.

[0009] Document WO 2020 / 221491 A1 discloses a transmission arrangement for a vehicle, in particular for a vehicle propelled by human power, comprising an input shaft, a countershaft, an output shaft, and a plurality of shiftable first gear sets. A machine gear is connected or connectable to one of the shafts. Drive torque from an electric machine can be introduced via the machine gear. The first gear sets connect the input shaft and the countershaft and form a first partial transmission. At least one second shiftable gear set connects the countershaft and the output shaft and forms a second partial transmission. The machine gear is arranged in the axial direction between the first partial transmission and the second partial transmission. A control device serves to control a switching device for the gear sets and to control the electric machine.The control device is designed to perform a shifting operation of at least one of the gear sets by means of the shifting device during a period in which the muscle-power torque periodically acting on a drive shaft is minimal. The muscle-power torque is generally minimal when the cranks are vertical (dead-center position).

[0010] Against this background, it is an object of the invention to provide an improved drive unit for a vehicle, an improved vehicle that can be driven by muscle power and an improved method for controlling a drive unit, wherein at least one gear change is improved, in particular with regard to comfort and / or loss of traction.

[0011] The above object is achieved by: a drive unit for a vehicle, in particular for a vehicle that can be driven by muscle power, such as a bicycle, with a gear arrangement for setting up a plurality of gear stages, in each of which a positive connection between two gear elements is set up, wherein the gear arrangement has an input shaft that can be connected to drive cranks and an output shaft that can be coupled to an output, and with a control device for carrying out gear changes, wherein the control device is set up to carry out the following steps: receiving a gear shift request to a target gear stage, calculating an optimal start condition of the gear shift process, and starting the gear shift process when the optimal start condition is met, so that the positive connection of the target gear stage is set up at an optimal time.

[0012] Furthermore, the above object is achieved by a vehicle that can be driven by muscle power and has a drive unit according to the invention.

[0013] Finally, the above object is achieved by a method for controlling a drive unit according to the invention by means of the control device, in particular with the above-mentioned steps.

[0014] The drive unit according to the invention makes it possible, after receiving a gearshift request to a target gear (preferably from a source gear), to first calculate an optimal starting condition for the gearshift process. When calculating the optimal starting condition, the following state variables of the drive unit or the vehicle can be taken into account: a current crank position, a current crank frequency (cadence), and a planned speed of a gearshift actuator used to execute the gearshift process. Additional state variables can be considered.

[0015] For example, the optimal starting condition can take into account the type of gear change, in particular whether it is a single gear change, a double gear change, or a multiple gear change. A double gear change (also called a double shift) is a gear change in which there is at least one further gear change between a source gear and a desired target gear, for example a gear change from gear 2 to gear 4. A single gear change is generally a gear change from a source gear to an adjacent target gear, for example a gear change from gear 2 to gear 4. Furthermore, when calculating the optimal starting condition, it is preferably taken into account whether it is an upshift (for example from a low source gear to a higher target gear, e.g. from 2 to 3) or a downshift (e.g. from 3 to 2).

[0016] Establishing the positive engagement of the target gear is usually accompanied by the release of the positive engagement of the source gear. During a downshift, the positive engagement of the source gear is typically released before the positive engagement of the target gear is achieved. During an upshift, the positive engagement of the source gear is usually released after the positive engagement of the target gear is achieved.

[0017] The optimum point in time is a point in time at which, for example, a crankset of the vehicle, through which muscle power is introduced to drive the vehicle, is in a certain position or in a certain range around such a position. For example, the optimum point in time is reached when the crankset is in the dead center position (where the cranks are essentially aligned vertically, regardless of which crankset pedal is up and which is down). The dead center position is the angle or angular range of the crankset at which the relatively lowest torque is introduced via muscle power. The highest muscle power torque introduced occurs when the crankset is aligned horizontally. By setting the positive engagement of the target gear at the optimum point in time, the shifting process can be carried out with a relatively low load.This has a positive effect on gearshift noise and consequently reduces driver irritation. This improves overall driving comfort. Furthermore, gearshifts can be performed more reliably.

[0018] While the prior art teaches stopping or reducing the engine drive torque of the drive motor before a gear shift is carried out (DE 102012 107 939 B4, see above), with the drive unit according to the invention, a gear shift can be carried out in most cases without reducing the engine drive torque of the drive motor. The optimal starting condition is calculated by calculating a shift time or an angular range of the crankset required for the shift process. This calculation is preferably carried out as a function of at least the current crankset position, the current crank frequency (cadence), and the actuator speed intended for the shift process. If this shift time orOnce this shift angle has been calculated, the shifting process can be initiated when the shifting time elapses at the optimal point, i.e., essentially when the crankset reaches its dead center position. The shifting time is defined as the period from the start of the shifting process until the positive engagement of the target gear is reached or established.

[0019] The start of the shifting process preferably coincides with the beginning of actuation of a shift actuator. The shift actuator is preferably an electric shift actuator. The start of the shifting process therefore preferably coincides with the beginning of energization of the shift actuator.

[0020] If in this case reference is made to reaching the dead center position, it is understood that this can also mean an angular range around the dead center position, unless expressly defined otherwise.

[0021] The two transmission elements of the transmission arrangement, between which a positive connection is created to establish a gear stage, are preferably a shaft of the transmission arrangement (preferably a countershaft) and an idler gear of a spur gear set mounted thereon, which is assigned to a gear stage. An idler gear is generally a gear rotatably mounted on the shaft.

[0022] The positive connection between these two transmission elements (shaft and idler gear) can be achieved in any way, e.g. by means of a claw clutch or a synchronized clutch (similar to manual transmissions in motor vehicles).

[0023] It is particularly advantageous if the positive connection between the two gear elements (shaft and idler gear) is established by means of a switching pawl or a switching cam. Such a switching pawl is preferably mounted on one gear element (shaft) so as to be pivotable essentially in the radial direction. Preferably, a camshaft is rotatably mounted radially inside the shaft designed as a hollow shaft and is designed to move the switching pawl, depending on the relative rotational position between the camshaft and shaft, either into a position in which no positive connection is established between the two gear elements, or into a position in which positive connection is established between the two gear elements.

[0024] With regard to the transmission arrangement, its shafts and the switching arrangement for switching gear stages of the transmission arrangement, reference is made to document WO 2020 / 221491 , the disclosure content of which is intended to be incorporated in full herein.

[0025] The problem is thus completely solved.

[0026] Overall, it is advantageous if the calculation of the optimal starting condition is carried out at least on the basis of (i) the current position of a crankset, (ii) the current rotational frequency (cadence) of the crankset, (iii) an intended (set) speed of a shift actuator used to establish the positive engagement of the target gear stage and (iv) an actuator travel until the positive engagement of the target gear stage is established.

[0027] With these four parameters, to which others may be added as described above and below, it is possible to calculate when it is optimal to initiate the switching process, i.e. to actuate the switching actuator (in particular to energize it), i.e. to start the switching process when the optimal start condition is met.

[0028] This makes it possible to ensure that the positive engagement of the target gear stage can be set at an optimal time, in particular at a dead center position, i.e. when a relatively low torque is applied to the crankset.

[0029] As mentioned above, with the drive unit according to the invention, it is generally not necessary to reduce the engine drive torque of a drive motor for or during a gear change. This applies in particular to so-called single gear changes. In a preferred embodiment, which is particularly applicable to double or multiple gear changes that require a longer time than a single gear change, a drive motor of the drive unit is configured to feed an engine drive torque into the transmission arrangement for driving the vehicle, wherein the control device is configured to reduce the engine drive torque of the drive motor after the gear change has started.

[0030] This allows the time for which the engine drive torque is reduced to be reduced compared to the prior art (where the engine drive torque is reduced before initiating the gear change), so that the gear changes can be made more comfortable.

[0031] According to a further preferred embodiment, the control device is designed to reduce the engine drive torque of the drive motor before the final gear of the target gear stage is established.

[0032] This variant also applies preferably only to double or multiple gear changes, but preferably not to single gear changes.

[0033] It goes without saying that the motor drive torque is preferably increased again after the mold closing position has been reached, particularly depending on the gear. The motor drive torque is preferably increased again as quickly as possible and, in some cases, can occur before the mold closing position is reached.

[0034] According to a further preferred embodiment, the control device is designed to adapt an engine speed of a drive motor to a gear ratio of the target gear when the final position of the target gear is reached.

[0035] This type of adjustment is carried out particularly in single circuits.

[0036] Alternatively, the control device is designed to set a time period before the

[0037] Reaching a positive locking position of the target gear stage, an engine speed and / or an engine drive torque of a drive motor is adapted to a gear ratio of the target gear stage.

[0038] This alternative is used particularly for double upshifts. In this context, the term "double shift" is intended to encompass, on the one hand, shifting operations that are to take place via an intermediate gear, for example, from gear 2 to gear 4. However, the term "double shift" can also encompass shifting operations in which a gear change (whether directly or via an intermediate gear) involves a shift in two sub-transmissions. This applies in particular to transmission arrangements that include two sub-transmissions in the manner of a group transmission, as disclosed in the above-mentioned document WO 2020 / 221491.

[0039] In general, it is preferable to adjust the engine drive torque and engine speed in a coordinated manner when the target gear position is reached. This can prevent gear changes from being perceived as "disharmonious."

[0040] Overall, as already described above, it is advantageous if the control device is connected to a switching actuator which has a switching motor, preferably a switching electric motor.

[0041] The shift actuators may include conventional claw clutches or means for axially shifting gears or synchronous shift clutches, similar to those used in manual automotive transmissions.

[0042] However, it is particularly advantageous if the switching actuator has a camshaft which is preferably arranged coaxially to a countershaft, in particular inside a countershaft.

[0043] In this case, it is further preferred if switching pawls or cams are mounted on the countershaft, which - by means of a relative rotation of the camshaft with respect to the countershaft - either engage with idler gears rotatably mounted on the countershaft (in order to establish the positive connection for the associated gear steps) or disengage in order to release a positive connection.

[0044] For details of such a switching actuator system, reference is made to document WO 2020 / 221491 , the disclosure of which is incorporated herein by reference.

[0045] It is further preferred if the control device is configured to actuate the shift actuator in the direction of a final form position of the target gear when a shift request is received and to terminate the actuation after the final form position is reached and / or before a target position is reached, so that the target position can be reached due to mass inertia.

[0046] In general, it is also conceivable to terminate the control beforehand, for example, by no longer energizing a shift electric motor before the final position is reached. However, the control of the shift actuator is usually not terminated when the final position is reached, since a source gear must preferably be disengaged subsequently, and this also requires a certain shift actuator force (or torque).

[0047] A target position is therefore a position at which the gear change is completed, i.e. a target gear is engaged and, if applicable, a source gear is disengaged.

[0048] According to a further preferred embodiment, the calculation of the optimal starting condition of the shifting process includes calculating whether a positive locking position of the target gear stage can be reached by reaching a next dead center position of the input shaft, or whether the positive locking position of the target gear stage can only be reached by reaching a second but one dead center position of the input shaft.

[0049] In this case, the input shaft is generally connected to a crankset. The next dead center position, based on the current crankset position, is the position of the crankset at which the cranks of the crankset are next vertically aligned. When calculating the optimal starting condition, a certain time is usually determined that is required from the current state until the positive engagement of the target gear stage is reached, in particular a certain time period (shift time) or a certain shift angle range (which, at a constant rotational speed of the crankset, is proportional to the shift time).

[0050] If, for example, the crankset is relatively close to a dead center position, there may not be enough time to establish the positive locking until this (i.e., the next) dead center position. In this case, the control unit detects that the shifting process will not start until the next dead center position has been passed through, ideally before reaching the next dead center position, or, if, for example, the cadence is very high and the shifting time is very long, ideally before reaching the next dead center position.

[0051] This ensures that the gear shifting process can always be started optimally depending on the current crankset position.

[0052] According to a further preferred embodiment, which in conjunction with the preamble of claim 1 constitutes a separate invention, the control device is designed to adjust an actuator speed of a switching actuator system depending on the type of switching operation.

[0053] The actuator speed is usually adjusted by the size of a current (actuator size) of an electric switching actuator, in particular a switching electric motor, via a suitable pulse width modulation (PWM) setting, or in the case of a BLDC motor by a corresponding control of the same.

[0054] If the gear shift should be as fast as possible, a higher actuator speed is selected. This is especially the case with double or multiple gear shifts. For single gear shifts, however, a lower actuator speed is usually sufficient. This can reduce wear and tear and also lower the energy consumption for performing the gear shift. Furthermore, the driver's perceived shift duration can be harmonized.

[0055] It is therefore particularly advantageous if the control device is designed to set the actuator speed of the shift actuator higher during a double or two-speed gear change than during a single-speed gear change.

[0056] According to a further preferred embodiment, which in conjunction with the preamble of claim 1 constitutes a separate invention, the control device is designed to detect an actuator position of a shift actuator for carrying out gear changes and, in the event that the shift actuator has exceeded an actuator position corresponding to the target position of the target gear during a shift into a target gear, to control the shift actuator in an opposite direction.

[0057] This embodiment relates to a case in which, for example, due to excessive actuator speed, the shift actuator has moved past the target position. In this case, the shift actuator is moved back and then subsequently driven toward the target position again, thus making a second attempt to complete the gear change.

[0058] It is advantageous if the control device is designed to reduce an actuator speed of the switching actuator during such a subsequent control in the direction of the target position.

[0059] This can reduce the likelihood of a repeat overshoot. Otherwise, a constant "ping-pong" could occur between overshooting the target position, retracing, and overshooting the target position again.

[0060] According to a further preferred embodiment, which in conjunction with the preamble of claim 1 represents a further invention of its own, the control device is designed to detect an actuator position of a shift actuator for carrying out gear changes and, in the event that the actuator position does not change for a specific blocking period during a shift into a target gear before reaching a final position of the target gear, to control the shift actuator in a pulsating manner with regard to a control variable and / or to control the shift actuator in a pulsating manner with regard to a shift path back and forth.

[0061] This embodiment addresses a case in which, for whatever reason, a certain blockage of the switching actuator occurs before reaching the positive locking position. To resolve this blockage, the switching actuator is preferably rapidly switched on and off in order to "shake off" the blockage due to this pulsating control. Alternatively or additionally, the switching actuator can be controlled in a pulsating back and forth motion with respect to the switching travel, so that a kind of hammer movement against the blocking position occurs to resolve this blockage.

[0062] It is particularly advantageous if the control device is designed to abort the switching process if, despite the pulsating control of the switching actuator for a pulsation period or for a predetermined (maximum) number of pulses, the final position of the target gear stage is not reached.

[0063] In other words, if the blockage cannot be resolved even by pulsating the shift actuator (either in terms of the control value or the shift travel), the shifting process is aborted and the source gear remains engaged. Preferably, the shift actuator is then moved back to the actuator position of the source gear. If necessary, an error message is issued.

[0064] According to a further preferred embodiment, which in conjunction with the preamble of claim 1 constitutes a separate invention, the control device is configured to detect a multiple gearshift request (e.g., a request for a double gearshift or a multiple gearshift) and, in this case, to set the actuator speed of a gearshift actuator system higher than for a single gearshift. This was already discussed above and applies not only to double gearshifts but also to multiple gearshifts. A multiple gearshift is understood to mean shifting more than one gear within a short period of time.

[0065] It is generally assumed that, for a shift actuator system that uses a camshaft, as discussed above, a camshaft rotation angle to perform a double shift is >150°, in particular >170°. Consequently, the shift process must be initiated significantly earlier for a double shift than for a single shift, where the rotation angle to perform the entire gear change is generally less than 90°, in particular less than 70°.

[0066] In order to avoid making the switching times too different, the actuator speed is increased during a double switching operation or multiple switching operation.

[0067] According to a further preferred embodiment, which in conjunction with the preamble of claim 1 constitutes a separate invention, the control device is designed to check, after the positive engagement of the target gear stage has been established, whether the positive engagement has been established at the optimal time and, if not, to incorporate the deviation into the future calculation of the optimal starting condition.

[0068] This allows the algorithm for calculating the optimal starting condition to be executed in a self-learning manner.

[0069] To determine when or at which crank angle position the positive locking mechanism has been achieved, a change in the input or output speed, a change in the (driver) input torque curve, an observation of the current requirement of the shift actuator motor, or even a change in the shift actuator motor speed can be used. Typically, the speed of the shift actuator increases significantly when the blockage is overcome or when the positive locking mechanism "falls into place."

[0070] According to a further preferred embodiment, which in conjunction with the preamble of claim 1 constitutes a separate invention, the control device is designed to learn a dead center position and preferably to incorporate it into the future calculation of the optimal starting condition.

[0071] Preferably, the dead center position can be learned by the setter / driver based on a manual calibration (preferably initially during commissioning). For this purpose, the control device can be configured to prompt the setter / driver via a selectable menu item to manually set and confirm a dead center position, and to save the result.

[0072] Alternatively or additionally, the learning process can involve updating the dead center position during operation, preferably a permanent update. The update can be initiated, for example, by the control device upon the occurrence and detection of a significant deviation between the currently detected dead center position and a stored dead center position, preferably automatically by the control device.

[0073] For example, the control unit can store a current value of the dead center position. Furthermore, a detection algorithm for the dead center position can be stored in the control unit.

[0074] The detection algorithm preferably detects the current dead center position as a function of the torque a driver feeds into the transmission assembly (driver torque). For this purpose, a torque detection device, such as that described in the above-mentioned document WO 2020 / 221491 under reference numeral 48, can be provided, for example.

[0075] The control device is preferably configured to monitor the driver torque over a certain angle of rotation (e.g., approximately 1 revolution or a number n of crank position measurements). It is preferably provided to interpret the minimum driver torque and the corresponding crank position within this series of measurements as the dead center position. Generally, a single detection of the dead center position is sufficient. However, this detection preferably occurs regularly, particularly preferably continuously, i.e., continuously, especially when a significant deviation is detected (see above).

[0076] The dead center positions determined through regular detection can preferably be averaged. Particularly preferred is the formation of a running average, in particular based on a FIFO buffer memory that stores the n most recently detected dead center positions. The value of n can, for example, be in the range from 10 to 1000, preferably in the range from 50 to 200.

[0077] These determined dead-center positions can be used, for example, to update a permanent average value. The stored dead-center position thus becomes increasingly more accurate.

[0078] If the dead center position suddenly deviates significantly (for example because the cranks have been mounted offset in the meantime), the learned mean value of the dead center position is preferably reset and the learning process starts again.

[0079] When determining the dead center position, not only the driver torque curve can be used, but also other variables such as the cadence curve.

[0080] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0081] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show:

[0082] Fig. 1 is a schematic representation of a muscle-powered vehicle having a drive unit according to an embodiment;

[0083] Fig. 1a is a schematic representation of different angular positions of a crankset of the drive unit of Fig. 1; Fig. 2 is a time sequence diagram of a cadence, a crank position, a motor drive torque of a drive motor, a shift request, and a shift motor actuation during a shifting process;

[0084] Fig. 3 is a diagram of a control variable of a switching actuator versus a switching travel position;

[0085] Fig. 4 is a timing diagram of an actuator control variable over time in a pulsating control; and

[0086] Fig. 5 shows an illustration of an actuator position over time with a pulsating control with forward and backward movement.

[0087] Fig. 1 schematically shows a bicycle 10 with a frame 12. The frame 12 includes a down tube 14, a seat tube 16, and a rear triangle 18 (swing arm). The bicycle 10 further includes a drive unit 20.

[0088] The drive unit 20 has a housing 21 which is fixed to the frame 12.

[0089] The drive unit 20 includes a gear arrangement 22, schematically indicated in Fig. 1, for establishing a plurality of gear stages, each of which features a positive engagement between two gear elements. Fig. 1 schematically shows a first gear element 24, for example, in the form of an idler gear, which is rotatably mounted on a countershaft 26. A countershaft 26 can form a second gear element.

[0090] By establishing a positive connection between the first and the second transmission element 24, 26, the first transmission element 24 is connected in a circumferential direction in a rotationally fixed manner to the second transmission element 26 in order to engage a gear stage assigned to the first transmission element 24. To establish the positive connection, a positive connection element can be used, such as a switching pawl (or a switching cam) which can be actuated by means of a camshaft not shown in Fig. 1. The transmission arrangement 22 includes an input shaft 30 which is rotationally connected to a crankset which, in a manner known per se, includes drive cranks 32a, 32b. In Fig. 1, the crankset is shown in a dead center position, i.e. a vertical position.

[0091] The transmission assembly 22 further includes an output shaft 34 which is connected to an output 36, for example, a chain drive to a rear wheel (not shown) of the bicycle 10. Preferably, the output shaft 34 is therefore rotationally connected to a chain wheel or to a toothed belt wheel or the like.

[0092] The transmission assembly 22 further includes a shift actuator 38, which is schematically illustrated in Fig. 1. The shift actuator 38 can include the aforementioned camshaft, by means of which the locking elements 28 can be actuated to engage and disengage gear ratios. The shift actuator preferably includes a shift actuator, in particular in the form of a shift electric motor 40, which is designed to rotate the camshaft, in particular relative to the countershaft 26. In a special embodiment, the shift actuator and / or a shift electric motor can also be located within the countershaft or another shaft.

[0093] The drive unit 20 further includes a drive motor 42 configured to supply a motor drive torque to the transmission assembly 22 for driving the vehicle. The drive motor 42 is preferably an electric motor, which preferably supplies additional drive power to the transmission assembly, i.e., in addition to a muscle-power torque supplied via the crankset.

[0094] The drive motor 42 is controlled by a control device 44. Preferably, the drive motor 42 is controlled depending on the magnitude of a muscle-power torque supplied via the crankset.

[0095] The drive unit 20 can essentially correspond to a drive unit as disclosed in document WO 2020 / 221491, the disclosure of which is incorporated herein by reference. The gear arrangement 22 therein corresponds to a gear arrangement 16. The cranks 32a, 32b therein correspond to cranks 18, 18'. The first gear element 24 here in the form of an idler gear corresponds to an idler gear of one of a plurality of idler gears of switchable gear sets R1 to R7. The second gear element 26 here corresponds to a countershaft. The closing element 28 here in the form of a locking element corresponds to respective switching pawls S1 to S7, which are switched by means of respective switching cams N1 to N7 of a camshaft 44. The input shaft 30 here corresponds to a drive shaft 26. The output shaft 34 here corresponds to an output shaft 36. The output shaft 36 here corresponds to a chainring 20.The switching electric motor 40 here corresponds to a switching motor 68. The drive motor 42 here corresponds to an electric machine 22. The control device 44 here corresponds to a control device 88. As described in document WO 2020 / 221491, the drive unit 20 here (drive unit 10 there) can detect a plurality of sensors, for example, a rotation angle sensor 54 for detecting a position of the crankset and preferably for simultaneously detecting a rotational frequency of the crankset. Furthermore, the drive unit 20 here can include a switching position sensor 72, by means of which an actuator position of a switching actuator can be detected and by means of which an actuator travel of the switching actuator can be detected. In addition, the drive unit here can include a rotor position sensor 76 for detecting a rotor position of the drive motor 42.

[0096] The control device 44 is configured to receive a gear shift request to a target gear, to calculate an optimal start condition of the shifting process required for this purpose, and to start the shifting process when the optimal start condition is met, so that the final gear of the target gear is set at an optimal time, in particular at the time of reaching a dead center position, as shown in Fig. 1.

[0097] This is illustrated schematically in Fig. 1a. In solid lines, the crankset 32a, 32b is shown in a current position in which it is arranged at a current crankset angle ai from the next dead center position, whereby it is assumed that the crankset rotates in a drive direction at an angular velocity © (corresponding to a cadence). It is assumed that in the current position shown, which is designated ti, Pi in Fig. 1a, a gearshift request to a target gear is received. An optimal start condition for the shifting process is then calculated based on the current position ai of the crankset, the current rotational frequency (angular velocity) of the crankset (corresponding to co), a speed of a shift actuator 40 used to establish the positive engagement of the target gear, and an actuator travel until the positive engagement of the target gear is established.This results in a specific switching time which, at the assumed rotational frequency, corresponds to a crank travel or crank angle range which is indicated in Fig. 1a with «2. If the end of the target gear stage is to be achieved when the dead center position shown in Fig. 1a with tR, PR is reached, the switching process in the present embodiment is started or initiated in an optimal crankset position P2 (corresponding to an optimal starting time for the start of the switching process) (e.g. by energizing the switching electric motor 40), so that with an assumed constant angular speed © of the crankset 32a, 32b, the end of the target gear stage is reached exactly at the end position P , i.e. at the next or following dead center position.It is understood that instead of an optimal starting condition in the form of an optimal crankset position, the optimal starting time t2 can also form an optimal starting condition, whereby the calculated time tR of reaching the final position is then taken into account.

[0098] If, in the illustration in Fig. 1a, the current crankset position upon receipt of the gearshift request is such that the expiration or the end of the shift path 012, seen in the direction of rotation, is behind the form final position PR, the optimal crankset position P2* is assumed to be a position which is so before the next but one dead center position that with the calculated crank angle range a.2* the form final position PR* is reached with the next but one dead center position, i.e. usually less than one whole crankset rotation later.

[0099] Because the positive engagement of the target gear is established in a dead center position, the target gear can be engaged particularly comfortably and quietly. As a rule, the gearshift can be performed without reducing the motor drive torque provided by the drive motor 42. However, if the gearshift involves a double shift, in which the required crank angle range a2 is generally longer than shown in Fig. 1a, e.g., > 150°, it may be advantageous to reduce the motor drive torque of the drive motor, but only after the gearshift has started and generally before the positive engagement of the target gear is established.

[0100] In such a desired double switching process, it is also preferred if an actuator speed of the switching actuator 38 (angular speed of the switching electric motor 40) is increased compared to an actuator speed that is set in a single switching process.

[0101] In the case of double upshifts, it is also preferable if the engine speed of the drive motor is adapted to the new gear ratio of the target gear a period of time before the positive engagement position of the target gear is reached.

[0102] As mentioned above, in single-shift systems it is usually sufficient to adjust the engine speed and / or the drive torque of the drive motor to the ratio of the target gear when the final position is reached.

[0103] In general, when changing gears where a final gear change is to be carried out between transmission elements (such as double shifts in two partial transmissions) that are subject to the engine drive torque, it is preferable to reduce the engine drive torque before the final gear change.

[0104] Fig. 2 schematically illustrates the timing of a gear shift. Fig. 2 shows various timing diagrams 50, including a cadence or angular velocity © of the crankset over time, a crank position P over time, a motor torque M of the drive motor 42 over time, a gear shift request trigger over time, and an actuator variable (PWM corresponding to a motor current) of the switching electric motor 40. Fig. 2 shows that © is essentially constant. This results in an essentially harmonic sine wave of the crank position between two dead center positions TDC, TDC (shown is essentially the time course of the position of one crank in order to simplify the overall gear shift).

[0105] Furthermore, for the sake of simplicity, it is shown that the engine drive torque M can remain essentially constant, i.e., is not reduced during a gearshift. However, as mentioned above, it is preferred if the engine drive torque M follows the driver torque approximately sinusoidally, in particular, is proportional to the driver torque (not shown). Even with this alternative, the engine drive torque M is preferably not reduced during a gearshift.

[0106] It is also shown that a gear shift request is received at time t1. According to Fig. 2, the gear shift request is received at a crank position Pi that is shortly before a mid-position between two dead center positions, similar to the crank position Pi in Fig. 1a. Upon receipt of the gear shift request, the control device calculates the optimal start condition for the gear shift process, namely an optimal start time t2 (see Fig. 2) corresponding to an optimal crank position for the start of the gear shift process (P2). At this time t2, the switching electric motor 40 begins to be energized (PWM = normal for a single shift or PWM = double for a double shift). The energization occurs at least for a period ΔtR until the next dead center position OT is reached (corresponding to PR and tR in Fig. 2).

[0107] By appropriately determining the start of the switching process, it can be achieved that the final position of the switching actuator is reached exactly at the time (t ) when the dead center position is reached.

[0108] In general, it is conceivable to terminate the actuation of the switching electric motor 40 upon reaching the final position of the form. However, Fig. 2 shows that the switching electric motor 40 is energized for a further period of time after reaching the final position tR, namely until a target position is reached at a time tz, at which it is achieved that not only the positive engagement of the target gear has been achieved, but also the source gear has been disengaged. The shift pawls, as described, for example, in document WO 2020 / 221491, are generally designed as freewheel pawls, so that, particularly during upshifts, the source gear can remain engaged until a time after the positive engagement of the target gear has been established.When the target position is reached, the source gear is then disengaged so that the corresponding shift pawl is no longer in the freewheel position but actually disengages from the corresponding transmission element.

[0109] In Fig. 3, the current supply of the switching electric motor 40 is shown over the position of the switching electric motor 40 (corresponding to a camshaft position of a camshaft).

[0110] It can be seen that the motor is energized until the final position PR of the target gear stage is reached. A target position Pz lies behind the final position P in the direction of actuator movement. The source gear stage is disengaged at the target position Pz.

[0111] To prevent the target position Pz from being accidentally "overrun," for example, due to backlash in the switching actuator 38 and / or due to mass inertia, the switching electric motor 40 is preferably switched off before the target position Pz is reached, as shown at Pb (below the acceptance limit for the target position Pz). Fig. 3 also shows a lower acceptance range APB and an upper acceptance range APt for the target position. The switching electric motor 40 should be switched off such that the time Pb lies within the tolerance or acceptance range.

[0112] The lower acceptance range APb lies between the target position Pz and the lower acceptance limit PB. The upper acceptance range APt lies between the target position Pz and the upper acceptance limit for the target position (Pt).

[0113] Alternatively, instead of prematurely switching off the switching electric motor 40, it is also possible to provide a permanent control loop (e.g. PID controller) by means of which the target position is controlled (by comparing the target position as the setpoint position with the current actuator position). Fig. 4 schematically shows a time sequence when a blockage occurs before the mold closing position is reached (corresponding to a time tR) (blockage time tßi). In this case, the switching electric motor 40 can be controlled in a pulsating manner such that the control variable (PWM) is switched on and off in a pulsating manner. Fig. 4 shows that the actuator variable is switched off completely. However, a reduction in the actuator variable with a pulse-like characteristic can also be provided. The pulsating control takes place over a blockage period TBL, within which the mold closing position should be reached at t.Instead of a blocking period, a number of pulses can also be measured. The term "blocking period" can therefore also refer to a specific number of pulses.

[0114] If the positive locking position is not reached within the blocking period TBL, the shifting process is aborted and the shift actuator returns to the position of the source gear.

[0115] Fig. 5 shows a further measure for removing a blockage at a time tßi. In Fig. 5, a switching travel position Pschait is plotted against time. A final position is shown at PR.

[0116] If, after the start of the switching process (t2), the switching electric motor 40 is moved toward the final position PR, a blocking can occur at a specific time tßi, as mentioned above. Instead of switching the current of the switching electric motor 40 on and off, as shown in Fig. 4, the switching electric motor 40 can also be moved back and forth one or more times, as shown during the blocking period TBI in Fig. 5, so that the switching actuator essentially "hammers" against the blocking position until, hopefully, the final position PR is finally reached at tR. If the final position PR is not reached, the switching process is aborted, as in the example in Fig. 4. List of reference symbols:

[0117] 10 bicycles

[0118] 12 frames

[0119] 14 Down tube

[0120] 16 seat tube

[0121] 18 Rear triangle (swing arm)

[0122] 20 drive unit

[0123] 21 housings

[0124] 22 Gear arrangement

[0125] 24 first gear element (e.g. idler gear)

[0126] 26 second transmission element (e.g. countershaft)

[0127] 28 Form of closing element (e.g. pawl or cam)

[0128] 30 Input shaft

[0129] 32a / b drive cranks

[0130] 34 Output shaft

[0131] 36 Output (e.g. chain drive to the rear wheel)

[0132] 38 Switch actuators

[0133] 40 switching electric motor

[0134] 42 drive motor

[0135] 44 Control device

[0136] 50 Time sequence diagram me t Time ti Time at reception of gear shift request t2 Optimal start time for start of shift process

[0137] Pi crankset position when receiving gear shift request

[0138] P2 optimal crankset position for start shifting ai current crankset angle (current position)

[0139] 02 Shift travel / shift angle range w Angular speed of crankset tz Time of reaching target position End of actuation of the shift actuator P Crank position

[0140] TDC dead center position 30 / 32a

[0141] M Drive torque 42 tR Time of reaching the final position of the mold

[0142] Ati remaining time until reaching the next TDC Ata remaining time until the form final position Atb control stop until the form final position

[0143] P Form final position 38

[0144] Tank target position 38

[0145] Pb lower acceptance limit for target position

[0146] Pt upper acceptance limit for target position

[0147] APb lower acceptance range for target position

[0148] APt upper acceptance range for target position

[0149] TBI Blockadezeitraum

[0150] PBI Blockadeposition 38

Claims

Patent claims 1. Drive unit for a vehicle, in particular for a vehicle driven by muscle power, comprising a transmission arrangement for establishing a plurality of gear stages, in each of which a positive engagement of two transmission elements is established, wherein the transmission arrangement has an input shaft which can be connected to drive cranks and an output shaft which can be coupled to an output, and a control device for carrying out gear changes, characterized in that the control device is configured to carry out the following steps: Receiving a gear shift request to a target gear, Calculating an optimal start condition for the shifting process, and starting the shifting process when the optimal start condition is met, so that the positive engagement of the target gear stage is established at an optimal time.

2. Drive unit according to claim 1, wherein the calculation of the optimal starting condition is carried out at least on the basis of (i) the current position of a crankset, (ii) the current rotational frequency of the crankset, (iii) a speed of a shift actuator used to establish the positive engagement of the target gear stage and (iv) an actuator travel until the positive engagement of the target gear stage is established.

3. Drive unit according to claim 1 or 2, comprising a drive motor which is designed to feed an engine drive torque for driving the vehicle into the transmission arrangement, and wherein the control device is designed to carry out the following steps: Reducing the engine drive torque of the drive motor after the switching process has started, and / or Reducing the engine drive torque of the drive motor before the positive engagement of the target gear stage is established.

4. Drive unit according to one of claims 1 to 3, wherein the control device is configured to adapt an engine speed of a drive motor to a gear ratio of the target gear when the final position of the target gear is reached.

5. Drive unit according to one of claims 1 to 3, wherein the control device is configured to adapt a motor speed of a drive motor to a gear ratio of the target gear stage a period of time before reaching the final position of the target gear stage.

6. Drive unit according to one of claims 1 to 5, wherein the control device is connected to a switching actuator, which preferably has a switching electric motor.

7. Drive unit according to claim 6, wherein the control device is configured, upon receipt of a shift request, to control the shift actuator in the direction of a positive locking position of the target gear stage and to terminate the control after the positive locking position is reached and / or before a target position is reached, so that the target position can be reached due to mass inertia.

8. Drive unit according to one of claims 1 - 7, wherein the calculation of the optimal starting condition of the shifting process includes calculating whether a positive locking position of the target gear stage can be reached by reaching a next dead center position of the input shaft or whether the positive final position of the target gear stage can only be reached by reaching a second but one dead center position of the input shaft.

9. Drive unit according to one of claims 1 to 8 or according to the preamble of claim 1, wherein the control device is designed to adjust an actuator speed of a switching actuator as a function of the type of switching operation.

10. Drive unit according to claim 9, wherein the control device is configured to set the actuator speed of the shift actuator system higher during a double gear change than during a single gear change.

11. Drive unit according to one of claims 1 to 10 or according to the preamble of claim 1, wherein the control device is designed to detect an actuator position of a shift actuator for carrying out gear changes and, in the event that the shift actuator has exceeded an actuator position corresponding to a target position of the target gear during a shift into a target gear, to control the shift actuator in an opposite direction.

12. Drive unit according to claim 11, wherein the control device is configured to reduce an actuator speed of the switching actuator during a subsequent control in the direction of the target position.

13. Drive unit according to one of claims 1 to 12 or according to the preamble of claim 1, wherein the control device is set up to detect an actuator position of a shift actuator for carrying out gear changes and, in the event that the actuator position does not change for a predetermined blocking period during a shift into a target gear before reaching a final position of the target gear, to control the shift actuator in a pulsating manner with regard to a control variable and / or to control the shift actuator in a pulsating manner with regard to a shift path back and forth.

14. Drive unit according to claim 13, wherein the control device is configured to abort the shifting operation if, despite the pulsating control of the shift actuator for a pulsation period, the final position of the target gear stage is not reached.

15. Drive unit according to one of claims 1 to 14 or according to the preamble of claim 1, wherein the control device is designed to detect a multiple gearshift request and, in this case, to set the actuator speed of a gearshift actuator higher than for a single gearshift.

16. Drive unit according to one of claims 1 to 15 or according to the preamble of claim 1, wherein the control device is designed to check, after the positive engagement of the target gear stage has been established, whether the positive engagement has been established at the optimal time and, if not, to incorporate the deviation into the future calculation of the optimal starting condition.

17. Drive unit according to one of claims 1 to 16 or according to the preamble of claim 1, wherein the control device is designed to learn a dead center position and preferably to incorporate it into the future calculation of the optimal starting condition.

18. Drive unit according to one of claims 1 to 17, wherein the optimal time is a time at which a crankset of the vehicle, via which muscle power is introduced to drive the vehicle, is in a dead center position, so that the establishment of the positive locking of the target gear stage coincides with the dead center position.

19. A muscle-powered vehicle having a drive unit according to any one of claims 1 to 18.

20. Method for controlling a drive unit according to one of claims 1 - 18 by means of the control device of the drive unit, in particular with the steps: Receiving a gear shift request to a target gear, calculating an optimal start condition for the gear shift, starting the gear shift when the optimal start condition is met, so that the positive engagement of the target gear is established at an optimal time.

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