Gearbox arrangement, drive unit and method for operating a drive unit for a vehicle

Description

[0001] The present invention relates to a transmission arrangement for a vehicle, in particular for a vehicle driven by muscle power such as a bicycle, having an input shaft, a countershaft, an output shaft which can be connected to a drive wheel of the vehicle, a plurality of switchable first gear sets which connect the input shaft and the countershaft and which are each assigned to at least one gear stage, and a machine gear which is connected or connectable to one of the shafts and can be introduced into the drive torque of an electric machine.

[0002] Furthermore, the present invention relates to a drive unit for a vehicle, in particular for a vehicle driven by muscle power such as a bicycle, having a transmission arrangement of the type described above and having an electric machine which is connected to the machine gear of the transmission arrangement.

[0003] Furthermore, the present invention relates to a method for operating a drive unit of the type described above.

[0004] A transmission arrangement according to the preamble of claim 1 is known from document DE 10 2011 120 675 A1. Further transmission arrangements are known from documents DE 10 2010 051 727 A1, DE 10 2016 225 163 A1, DE 10 2014 009 833 A1, and EP 2 388 781 A1.

[0005] Human-powered vehicles such as bicycles are usually equipped with gears to establish a variety of different gear ratios between a drive shaft connected to cranks and a drive wheel of the vehicle.

[0006] Such gear systems include hub gears, which have long been known as three-speed gear systems, for example. Most gear systems are designed as so-called derailleur systems, in which a bicycle chain can be engaged with different sprockets coaxial with a drive shaft and / or with different gears of a sprocket in the area of ​​the driven wheel (rear wheel).

[0007] Document DE 10 2008 064 514 A1 discloses a transmission unit for such a vehicle. It includes a through-shaft connected to pedal cranks for driving the vehicle, and a countershaft. Mounted on the countershaft are switchable idler gears, which, together with gears of the through-shaft and gears of an output shaft, form a partial transmission. The output shaft is arranged coaxially to the through-shaft. Such a transmission unit allows, for example, 18 different gear stages to be realized. Unlike derailleur gears, these gear stages each have completely different ratios and can achieve a wide range.

[0008] It is also common practice to equip bicycles with auxiliary motors. In one variant, a hub motor is located near the front or rear wheel hub. Such hub motors are usually offered in combination with derailleur gears. With rear hub motors, the combination with a hub gear is complicated because the motor requires a lot of space. This leads to high weight and unfavorable weight distribution, as the proportion of unsprung mass on the bicycle increases. Hub motors use slow-rotating electric motors that deliver relatively high torque. However, these are relatively large and heavy.

[0009] Another drive concept for bicycles with electric auxiliary motors involves installing the auxiliary motors as a mid-mounted motor in the bottom bracket area. This involves transferring the torque provided by the electric drive motor directly to a sprocket, which is usually arranged coaxially with the drive shaft (crank). This often presents problems because the chain cannot be shifted from one sprocket to another in the bottom bracket area. Consequently, the use of derailleur gears is limited.

[0010] From the above-mentioned document DE 10 2010 051 727 A1, a drive unit is known which connects a spur gear arranged in the area of ​​the pedal crank (as known from DE 10 2008 064 514 A1) with an electric auxiliary motor.

[0011] In this case, it is generally intended that the torque is fed into the gear arrangement at one axial end of the gear arrangement.

[0012] The above-mentioned document DE 10 2011 120 675 A1 discloses a torque detection arrangement for a human-powered vehicle. The torque is detected indirectly via a rotation angle between a drive shaft and an input shaft, which are resiliently connected in the rotational direction by a torsion spring element.

[0013] The unpublished German patent application with the file number DE 10 2018 101 911.4 discloses a further torque detection arrangement for a bicycle with an auxiliary motor, wherein a torsion spring, which resiliently connects an input shaft and a rotary member, is arranged within an input shaft designed as a hollow shaft.

[0014] Finally, the unpublished German patent application with the file number DE 10 2018 123 575.5 discloses a crank mechanism, wherein a converter unit is provided for converting an angular offset between a crank-side receiving area and a delivery area connected to a gear wheel into a change in a magnetic flux, wherein a magnetic field-sensitive sensor is provided for detecting the angular offset. In particular, the converter unit has at least one magnet and two mutually rotatable magnetic guide elements, which, within an air gap, change the shape of the air gap in a dependent manner through their shape and their relative angular position. The magnet can be a ring magnet arranged concentrically to the crankshaft.

[0015] Against this background, it is an object of the present invention to provide an improved gear arrangement, an improved drive unit and an improved method for operating a drive unit.

[0016] The above object is achieved by a transmission arrangement having the features of claim 1, wherein it is preferred if the first gear sets form a first partial transmission, wherein at least one second switchable gear set connects the countershaft and the output shaft and forms a second partial transmission, wherein the at least one second gear set is assigned to at least one gear stage and wherein the machine gear is arranged in the axial direction between the first partial transmission and the second partial transmission.

[0017] Furthermore, the above object is achieved by a drive unit for a vehicle of the type described above, with a transmission arrangement of the type according to the invention and with an electric machine which is connected to the machine gear of the transmission arrangement.

[0018] Finally, the above object is achieved by a method for operating a drive unit of the type according to the invention, wherein a shifting operation of at least one of the gear sets is carried out by means of the shifting device during a time period in which a muscle power torque periodically acting on a drive shaft is minimal; and / or wherein, upon detection of a shifting request, a torque provided by the electric machine is initially increased for a first short time period in order to at least tension the transmission arrangement, and subsequently the torque provided by the electric machine is rapidly reduced in order to place the transmission arrangement into a load-free state for a second short time period, wherein the shifting device is controlled in such a way that a shifting of a gear set occurs within this second short time period.

[0019] The transmission arrangement is designed as a spur gear arrangement and is configured to establish a plurality of gear stages. Drive torque from an electric machine is introduced into the transmission arrangement via a machine gear that is connected or connectable to one of the shafts. Preferably, the second sub-transmission has a plurality of second switchable gear sets. In this case, the transmission arrangement is designed in the manner of a group transmission. The number of selectable gear stages is determined by multiplying the number of first gear sets by the number of second gear sets.

[0020] The gear arrangement can be arranged, in particular, in the bottom bracket area. The input shaft is preferably coaxial with the output shaft. The input shaft and the output shaft are preferably coaxial with a crankshaft.

[0021] By arranging the machine gear axially between the two sub-gearboxes, it is possible for the torque generated by a driver using muscle power to be transmitted through both sub-gearboxes, while the drive torque provided by the electric motor is transmitted through the second sub-gearbox. In an alternative embodiment, however, it is also possible to connect the machine gear to the sub-gearboxes in such a way that the electric motor can also transmit drive torque through both the first sub-gearbox and the second sub-gearbox.

[0022] In the drive unit according to the invention, it is preferred if the electric machine is arranged with its longitudinal axis parallel to the shafts of the gear arrangement. In general, however, it is also conceivable for the electric machine to be arranged with its longitudinal axis transverse, in particular orthogonal, to the shafts of the gear arrangement. In this case, the electric machine could be connected to the gear arrangement, in particular to the machine gear, via an angular gear. In any case, it is preferred if the electric machine is or can be connected to the machine gear via a pre-transmission or a reduction gear. For example, the pre-transmission can have a pre-transmission shaft that contains two fixed gears. One of the fixed gears engages with a pinion of a rotor shaft. The other fixed gear engages with the machine gear.Alternatively, the pre-transmission can comprise a planetary gear set, preferably arranged parallel to a rotor shaft of the electric machine. The planetary gear set preferably comprises three elements, one of which is fixed to the housing in order to establish a fixed, high pre-transmission ratio.

[0023] The input shaft and the output shaft are preferably each designed as hollow shafts arranged around the drive shaft (crankshaft). The input shaft and the output shaft are preferably arranged axially offset on the drive shaft, with the machine gear preferably arranged axially therebetween.

[0024] The gear sets of the first and second manual transmissions are preferably operated by means of a shifting device having an electric shift motor. The shift motor can be arranged with its longitudinal axis parallel to the shafts of the transmission arrangement, or orthogonal thereto. In the latter case, the electric shift motor could be connected to a ring gear of a shifting device via a worm gear. The shifting device preferably further includes a camshaft arranged within the countershaft, which is designed as a hollow shaft. The camshaft rotates with the countershaft during operation. The countershaft and the camshaft are preferably connected to one another via a speed superposition gear, which preferably includes two coupled planetary gear sets. The coupling is achieved in such a way that the sun gears of these two planetary gear sets generally rotate at the same speed.Only when a rotary movement is initiated on a member of one planetary gear set (for example a ring gear of one planetary gear set) does a relative rotation occur between the camshaft and the countershaft, whereby a source gear can be disengaged and a target gear can be engaged.

[0025] The switching device preferably has a single-stage or multi-stage reduction gear (planetary, spur gear, worm or the like) in order to increase the torque or to make the switching motor smaller.

[0026] The combination of a manual transmission with multiple gears, an electric drive motor, and a shifting device with an electric shift motor is particularly advantageous. This is because it makes it possible to carry out shifting operations in such a way that these are coordinated, in particular synchronized, with a torque provided by the electric drive motor. This is particularly evident in the method according to the invention for operating a drive unit described above. The driver can still initiate a shifting operation, preferably via a switch or shift trigger provided on a handlebar. However, its actuation is detected by a control device, and on this basis, an actuator, in particular in the form of the aforementioned electric shift motor, is then controlled in coordination with the output of torque by the electric drive motor, in order to be able to carry out the shifting operation efficiently.

[0027] Preferably, a sensor unit is provided to detect a torque introduced by the driver, as well as the speed generated by the driver, and optionally a position of the crank position.

[0028] Instead of using sensors to detect the crank position, it is also conceivable to design the drive shaft so that the cranks can only be secured in a specific rotational position relative to it. In this case, the crank position can be derived from the rotational position of the drive shaft. Preferably, the cranks and a drive shaft have an irregular shape around their circumference. If the cranks are connected to the drive shaft via gearing, this can, for example, have an uneven pitch or a single, special, differently shaped tooth.

[0029] The shifting device preferably further comprises a position / speed sensor for controlling or regulating shifting operations. Furthermore, the shifting device preferably includes a single- or multi-stage reduction or speed adjustment gear for reducing the speed of the shift actuator (shift motor).

[0030] A control and power electronics, by means of which the electric drive motor and the switching motor can be controlled, are preferably part of the drive unit and are preferably accommodated within a housing of the drive unit.

[0031] The drive unit preferably has connections for other peripheral components, such as a battery, a human interface, a switch or shifter, a wheel speed sensor for detecting the speed of a driven wheel of the vehicle, and preferably universal interfaces (CAN bus), etc., in order to be able to access the electronics from the outside, for example for diagnostic, maintenance or software update purposes.

[0032] Due to the above-mentioned possibility of a coordinated execution of a switching process by means of a switching actuator and the provision of torque by means of the electric drive motor, it is possible to realize switching under full load.

[0033] In a preferred embodiment, the camshaft described above can also be used to control a controllable freewheel. In this case, the electric motor can be separated from the drivetrain for certain situations, for example, to avoid a clicking noise.

[0034] The camshaft can be constructed in multiple parts, e.g. one camshaft section for each sub-gearbox and one camshaft section for controlling a switching pawl assigned to the electric machine. The camshaft sections can be permanently connected, can be axially movable relative to one another, or can be connected to one another in a rotationally fixed manner over only a partial revolution. The camshaft of one or both sub-gearboxes can also have a geometry designed such that in one rotational position in one or both sub-gearboxes all freewheels are deactivated, i.e. no gear is engaged. In conjunction with the control system and a corresponding anti-theft device (PIN code, key), this can provide anti-theft protection in which the drive unit is in idle for the driver and / or electric machine.

[0035] The drive unit's gear assembly preferably runs in a fluid bath, particularly an oil bath. A fluid seal is preferably used between the gear chamber and the electric motors or electronics.

[0036] The fluid can be used as a heat transport medium to transport heat energy from areas with high heat input to areas with high heat capacity (e.g. gears and housings).

[0037] In a preferred embodiment, the fluid can also be actively transported to locations with high heat input. This can be achieved, for example, by spraying fluid into warm areas through the moving gears (similar to splash lubrication). Furthermore, it is also conceivable to pump fluid through cooling channels to structures thermally coupled to a heat source (e.g., electronics or stator winding overhangs) using a fluid pump. Separate heat sinks, heat exchangers, or the like can be provided for this purpose.

[0038] The fluid system for heat distribution and dissipation can also have a separate fluid volume that is not connected to the oil volume for lubrication. This would then require a separate reservoir or a completely closed circuit.

[0039] The electric motor of the drive unit is preferably a brushless direct current (BLDC) motor. The electric motor is controlled via power electronics. A rotor position sensor (magnet and sensor) is preferably positioned centrally on the rotor shaft of the electric motor. The electric motor preferably drives a multi-stage reduction gear, which can be integrated into the power flow of the drive unit in different positions and in different ways.

[0040] The electric machine is preferably mechanically connected to the transmission arrangement via a clutch or a freewheel, in particular to avoid dragging of the electric motor when driving over a speed bump (e.g. 25 km / h) or when driving without assistance.

[0041] When driving at speeds above 25 km / h, or in any other situation where the countershaft is rotating but the electric motor is not, it may be advisable to "co-operate" the electric motor at minimal torque to maintain the frictional connection of the electric motor's freewheel. This can prevent an impulse load (engagement shock) when the electric motor is reengaged.

[0042] The problem is thus completely solved.

[0043] As mentioned above, it is particularly advantageous if the machine gear is connected to one of the shafts, in particular to the countershaft, via a freewheel.

[0044] The freewheel can, in particular, be a switchable freewheel that can be activated and deactivated. The freewheel is preferably arranged coaxially with the one shaft.

[0045] By deactivating the switchable freewheel, the electric motor can be completely decoupled from the transmission unit. When the switchable freewheel is activated, a drive torque of the electric motor acting in the drive direction can be transferred to the corresponding shaft of the transmission assembly, for example, the countershaft. If the corresponding shaft rotates faster than the machine gear, the machine gear is "overtaken," which typically results in a freewheel clicking noise.

[0046] According to a further preferred embodiment, the machine gear is fixedly connected to the countershaft, wherein the electric machine can be connected to the machine gear via a separating clutch or a freewheel, in particular a switchable freewheel (e.g. an electromechanical friction or form-locking clutch).

[0047] While in the case of a freewheel connection between the machine gear and one of the shafts, this freewheel is generally arranged coaxially with the corresponding shaft, in the further variant, in which the electric machine is connectable to the machine gear via a separating clutch or a freewheel, this separating clutch or freewheel is preferably not arranged coaxially with one of the shafts of the transmission arrangement. The separating clutch can, in particular, be provided axially parallel, in particular on a machine / rotor shaft. The separating clutch is preferably arranged upstream of a pre-transmission gear.

[0048] The separating clutch can, for example, be a dog clutch, which is preferably actuated by an actuator such as an electric shift actuator. The separating clutch can be a normally closed clutch that is actuated when necessary to open the clutch. Alternatively, however, the separating clutch can also be a normally closed clutch or a bistable clutch.

[0049] According to a further preferred embodiment, the machine gear is connected via a freewheel to an intermediate shaft, which is fixedly connected to a loose wheel, rotatably mounted on the countershaft, of a gear set of the first gear sets.

[0050] The freewheel, via which the machine gear is connected to the intermediate shaft, is preferably a non-switchable freewheel, i.e. it is preferably not actuated by means of the camshaft.

[0051] As a result, a torque of the electric machine can be introduced into the first partial transmission via the one gear set, wherein one of the gear sets is preferably engaged in order to transmit muscle power torque to the countershaft.

[0052] Since the freewheel, via which the machine gear is connected to the intermediate shaft, is preferably not switchable, it is preferred for safety reasons if the input shaft is connected via a further, preferably non-switchable, freewheel to a fixed gear shaft to which fixed gears of the first gear sets are fixed.

[0053] This prevents the electric motor's drive energy from being transferred to the crankshaft (drive shaft) in certain situations, which can lead to a loss of comfort for the driver. Furthermore, safety can be improved because the electric motor cannot turn the crank without the driver's consent.

[0054] According to a further preferred embodiment, the machine gear is connected or connectable to an intermediate shaft which is arranged coaxially to the input shaft.

[0055] In one variant, the intermediate shaft is a fixed gear shaft to which the fixed gears of the first partial transmission are attached. In this case, it is preferred if the electric motor is connected to the machine gear via at least one non-switchable freewheel. The non-switchable freewheel can, for example, be integrated within the pre-transmission gear, for example, on a pre-transmission gear shaft thereof.

[0056] In this variant, it is preferred if the machine gear is arranged as a loose wheel coaxial with the countershaft and if there is no coupling possibility between the machine gear and the countershaft.

[0057] Furthermore, it is generally preferred if the intermediate shaft is connected to the input shaft via another non-switchable freewheel, as above, for reasons of comfort and / or safety.

[0058] In an alternative embodiment, the machine gear is rotatably mounted on the intermediate shaft and is connected to the intermediate shaft via a non-switchable freewheel. In this case, it is further preferred if the intermediate shaft is simultaneously the fixed gear shaft to which the fixed gears of the first partial transmission are attached. The fixed gear shaft is arranged coaxially around the drive shaft and / or input shaft. The fixed gear shaft is coupled to the input shaft via another non-switchable freewheel. The additional freewheel, in turn, serves comfort or safety reasons. In this preferred variant, both the one freewheel and the additional freewheel are arranged coaxially to the input shaft.

[0059] In this variant, it is further preferred if the machine gear meshes with a gear mounted on a secondary shaft that is axially parallel to the input shaft and the countershaft. In this case, the secondary shaft gear is part of a pre-transmission gear (see below).

[0060] Furthermore, it is generally conceivable to provide a switchable separating clutch in the power transmission path from the electric motor to the machine gear. In this case, it is possible to omit the one freewheel, nor the second freewheel, which is provided for comfort or safety reasons.

[0061] According to the invention, the electric machine is connected to the machine gear via a pre-transmission, wherein the pre-transmission is arranged axially overlapping with at least one gear set of the first gear sets and / or axially overlapping with at least one gear set of the second switchable gear sets.

[0062] In this way, a comparatively compact electric machine can be used. Furthermore, the gear arrangement can be realized with a short axial length. It is particularly preferred if the pre-transmission ratio is arranged so that it axially overlaps the gear sets of the second shiftable gear sets. Furthermore, in this case, it is preferred if the electric machine is arranged so that it axially overlaps the gear sets of the first shiftable gear sets.

[0063] An axial overlap can be understood as meaning that one or all gears of the pre-transmission are located with at least part of their circumference in the area of ​​a circumference of one or more gears of the first and / or second gear sets.

[0064] Furthermore, it is advantageous overall if the electric machine is connected to the machine gear via a pre-transmission, wherein the pre-transmission preferably has an intermediate gear which is rotatably mounted on a secondary shaft arranged offset parallel to the input shaft and the countershaft.

[0065] The pre-transmission makes it possible to use an electric motor as the drive source, which operates at high speeds and can therefore be designed compactly. The pre-transmission allows the relatively high speed of the electric motor to be converted into a speed suitable for connection to the transmission arrangement.

[0066] If the pre-transmission gear has an intermediate gear that is rotatably mounted on a pre-transmission shaft arranged parallel to the input shaft and the countershaft, a relatively large gear ratio can be achieved for the pre-transmission gear. In this case, it is preferred if the intermediate gear meshes, on the one hand, with a gear of the pre-transmission gear and, on the other hand, with a gear that is rotatably mounted coaxially to the input shaft.

[0067] According to a further advantageous embodiment, the input shaft is coupled to a drive shaft via a spring arrangement of a torque detection device.

[0068] The input shaft and the drive shaft are preferably rotatable relative to each other to a limited extent. The input shaft is preferably arranged as a hollow shaft around the drive shaft. The spring arrangement is preferably formed by a torsion spring, in particular in the form of a torsion bar spring. The deflection of the spring arrangement, for example the rotation of the torsion bar spring, can be detected in a suitable manner. This deflection is preferably proportional to a torque acting on the drive shaft, which is applied by a driver of the vehicle. Depending on this, the electric machine can then be controlled to provide electric drive torque as needed.

[0069] The drive shaft has axial splines at its ends for attaching cranks. The axial splines can preferably be designed so that they can be attached in just one or in two rotational positions offset by 180°.

[0070] In general, it is preferred if the gear arrangement is lubricated, in particular by means of an oil.

[0071] According to a further preferred embodiment, the gear sets of the transmission arrangement are arranged in a housing which defines a fluid sump for establishing lubrication for the gear sets, wherein a heat source is arranged in the housing and wherein the arrangement of the heat source in the housing is selected and / or the housing is designed such that the heat source is subjected to a flow of fluid which is taken from the fluid sump during operation, in particular is thrown upwards by means of an exchange lubrication.

[0072] This makes it possible to efficiently cool the heat source using the fluid. A fluid cooler can be integrated into the housing to cool the fluid.

[0073] According to a further preferred embodiment, the gear sets of the transmission arrangement are arranged in a housing in which a fluid sump for lubrication and / or cooling is arranged, wherein a fluid pump sucks fluid from the fluid sump, which fluid is used to cool a heat source such as power electronics or stator windings, in particular stator winding heads.

[0074] The fluid drawn in by the fluid pump can, for example, be fed into a cooling channel circuit integrated into the housing and used to cool the heat source. The heat source is preferably thermally coupled to the cooling channel. The fluid drawn in by the fluid pump can also be used for injection lubrication to direct fluid to a meshing area of ​​gears of the wheel sets. Furthermore, the drawn-in fluid can also be directed, by way of injection lubrication, to a heat source or a heat sink connected to it, which is housed in the housing.

[0075] In general, it is advantageous if the heat from the heat source is transferred to a heat storage element, which could be, for example, the gear set. The transfer can occur indirectly via the fluid. The gear set is comparatively large and heavy and therefore has a relatively high heat capacity.

[0076] In general, it is also advisable to cool the power transistors of a power electronics system using suitable cooling elements and the flow of cooling fluid. The power electronics can be the power electronics of the electric machine and / or the power electronics of a switching motor.

[0077] The electric machine preferably has a stator cooled by a cooling arrangement. Cooling can be achieved by directing fluid against a housing wall behind which the stator windings are arranged. Furthermore, the housing can have a cooling channel laid in the region of the stator windings to cool the stator windings with cooling fluid, which is supplied, for example, by a fluid pump. It is particularly preferred if cooling takes place in particular in the region of the stator winding overhangs of the stator windings.

[0078] In the drive unit according to the invention, it is preferred if a control device is provided for controlling a switching device for the gear wheel sets and / or for controlling the electric machine, and if a sensor arrangement is provided for detecting at least one state variable of the drive unit.

[0079] The control device is preferably integrated on a circuit board that is integrated into the housing of the drive unit. The circuit board is preferably housed in a region of the housing that is sealed from a fluid sump. The electric motor can also be housed in such a sealed region of the housing. The circuit board is preferably thermally connected to the housing.

[0080] It is particularly preferred if the sensor arrangement comprises a rotor position sensor for detecting a rotational position of a rotor of the electric machine and / or a switching position sensor and / or a speed sensor for detecting a speed of the input shaft and / or a rotational position sensor for detecting a relative rotational position of the input shaft and / or a crank position sensor for detecting a rotational position of cranks connected to a drive shaft and / or a torque sensor for detecting a muscle power torque introduced into a drive shaft.

[0081] The position sensors, the position sensors, and the speed sensors can each be formed by incremental encoders. An absolute rotary position can, if necessary, be detected via an index mark of a pitch of such an incremental encoder. The incremental encoder can, for example, be implemented by forming the individual increments by the teeth of a gear, with a sensor fixed to the housing being assigned to the teeth. Using a reference / index mark (e.g., by omitting a tooth or by only half-forming the tooth), the absolute rotary position can then also be detected, for example, the rotary position of an input shaft and thus of cranks.

[0082] A position sensor may be capable of detecting a rotation angle or a displacement position. A sensor for detecting the absolute rotational position of the drive shaft, together with information about the rotational position of cranks in relation to the drive shaft, can be used to detect the absolute position of the cranks that drive the drive shaft. The absolute position of the crank can preferably be used to determine when a muscle power torque acting periodically on a drive shaft is minimum or maximum. The muscle power torque is typically minimum when the cranks are vertical. The maximum muscle power torque is typically applied when the cranks are horizontal.

[0083] According to a further preferred embodiment of the drive unit, a printed circuit board is fixed to a housing, wherein the control device and / or at least one sensor of the sensor arrangement is arranged on the printed circuit board, wherein the control device preferably has power electronics for the electrical machine and / or power electronics for a switching motor and / or at least one microprocessor for carrying out an operating program according to the method according to the invention.

[0084] It is particularly advantageous if the rotor position sensor for detecting a rotational position of a rotor of the electrical machine and the switching position sensor for detecting a position of a switching device are arranged on such a common circuit board.

[0085] The circuit board is preferably arranged at an axial end of the housing, preferably in an orientation transverse to the axes of the shafts of the gear assembly.

[0086] Furthermore, it is advantageous if the control device is designed and configured to carry out a switching operation of at least one of the wheel sets by means of the switching device during a period of time within which a muscle power torque periodically acting on a drive shaft is minimal.

[0087] Determining when a periodic muscle torque acting on a drive shaft is at its minimum can be achieved by measuring the absolute rotational position of the cranks and / or a drive shaft / crankshaft of the transmission assembly. Typically, the torque is at its minimum when the cranks are vertical. This allows the gear shifting process to be performed with minimal stress on the transmission assembly, possibly even under load.

[0088] According to a further preferred embodiment, the control device is designed and configured, upon detection of a shifting request, to first increase a torque provided by the electric machine for a first short period of time in order to at least tension the transmission arrangement, and then to quickly reduce the torque provided by the electric machine in order to place the transmission arrangement into a load-free state for a second short period of time, wherein the switching device is controlled in such a way that a shifting of a gear set falls within this second short period of time.

[0089] The first short period of time is so short that the vehicle is not noticeably accelerated. Preferably, the first short period of time is shorter than half a period of the drive frequency at which the drive shaft is cranked. When the torque increases, the entire drive train is preferably tensioned. The energy stored therein is released when the torque of the electric motor is rapidly or abruptly reduced, so that the transmission arrangement is placed in a load-free state. The second short period of time is preferably shorter than the first short period of time.

[0090] A rapid reduction in torque preferably means that the torque is reduced within a period of time that is shorter than the first and second short periods of time. The increase in torque preferably occurs to a torque that is 70% to 200% of the maximum torque of the electric machine. When reducing the torque, the electric machine is reduced to a value of 5% to 25% of the maximum drive torque. When reducing the torque, the electric machine is not completely switched off or de-energized in order to avoid adverse effects caused by self-induction or mutual induction.

[0091] According to a further preferred embodiment, the control device is designed and configured such that the first short time period overlaps in time with a time period during which a muscle power torque acting periodically on a drive shaft is at a maximum, and / or the control device is preferably designed and configured such that the second short time period corresponds to the time period during which the muscle power torque acting periodically on the drive shaft is at a minimum.

[0092] In any case, it is advantageous if the switching process falls within this second short period of time, which preferably lies within a period of time in which the muscle power torque is minimized.

[0093] As mentioned above, it is preferred if the electric machine can be decoupled from the transmission arrangement via a separating clutch or via a switchable freewheel.

[0094] Accordingly, it is advantageous if the electric machine can be connected to one of the shafts via such a separating clutch or a switchable freewheel, wherein the separating clutch or the freewheel is actuated as required, so that (a) a sudden deactivation of a torque provided by the electric machine is possible, and / or (b) deactivation takes place if a control device does not receive an authorization signal, and / or (c) no clicking noise is audible when the electric machine is switched off.

[0095] Measure (a) may be implemented for security reasons. Measure (b) can be used to activate the drive unit only when the control device is supplied with a valid authorization signal, which can be triggered, for example, by an authorization device. Consequently, this can increase theft protection. The authorization device can, for example, contain a PIN code and / or a key. Furthermore, measure (c) can increase the convenience of the drive unit.

[0096] The methods according to the invention utilize the various components of the drive unit and their joint control via central electronics to significantly expand the functionality of the overall system. This provides several options, especially for implementing shifting under load. In this case, the rider does not need to consciously interrupt pedaling power to change gears. In principle, after the rider has initiated a gear change, the system should wait until the typically sinusoidal drive torque provided by the rider reaches a minimum. It is advantageous if the time of this minimum is anticipated. This time can be calculated using sensor data (speed, torque, etc.) and a corresponding analysis or forecast.

[0097] The shift motor preferably begins the shift process shortly before the expected minimum. This procedure may be sufficient if a shift process only occurs in the first sub-transmission, and the electric machine is connected between the first sub-transmission and the second sub-transmission. If a shift process also occurs in the second sub-transmission, via which the electric machine transmits torque, then the following procedure is preferably carried out. Shortly before the driver reaches the minimum drive torque and the shift motor is actuated, the drive torque from the electric machine is reduced. As a result, at the moment of shifting, the assistance torque of the electric machine is not present in addition to the driver torque at the affected sub-transmission.

[0098] A special option for improving shifting behavior under load is a strategy in which the transmission assembly or drivetrain is briefly tensioned and then relaxed to achieve a load-free state. In this state, the shift motor is then actuated and the gear is changed (disengaging a source gear and engaging a target gear).

[0099] It may be advantageous to activate the shift motor beforehand to initially accelerate the shift motor. In any case, the goal is for the shift motor to be activated as soon as the driver and electric motor torques together reach a minimum.

[0100] After the gear change has been completed, the torque of the electric motor is increased again to the appropriate assistance torque.

[0101] When reducing the torque, the electric motor is preferably not switched off completely, as this can lead to damage to the electronics due to reactive currents caused by induction phenomena.

[0102] To reduce torque as abruptly as possible, it may be advisable to deactivate the freewheel of the machine gear that drives the countershaft (or the input shaft, depending on the variant) from the electric motor. This can be achieved, for example, by using the internal camshaft, which deactivates the corresponding pawl of the switchable freewheel.

[0103] The process described above is based on the fact that all drive components exhibit both spring and damping properties due to their elasticity. With these properties, the components represent mechanical energy storage devices. Due to the "preloading" of the drivetrain when the torque of the electric motor is increased, the stored energy of the drivetrain (partial transmission, chain or belt, spokes of the rear wheel, rear wheel tire) is raised to a higher level. Since the load (driving resistance) on the rear wheel is inert (damping properties), and since the drive torque generated by the driver cannot be changed abruptly (damping properties), the suddenly released energy of the preloaded drivetrain counteracts the strain on the overall system.Because the system inputs and outputs are inert, the temporal dependence of the inertia results in the above-described short load-free period of the transmitting system, which can be used to change the gear in an at least almost load-free state.

[0104] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1 shows a bicycle frame with an embodiment of a drive unit according to the invention; Fig. 2 shows a further embodiment of a drive unit according to the invention in a perspective view without a housing; Fig. 3 shows a schematic view of a further embodiment of a drive unit according to the invention; Fig. 4 shows a schematic view of a further embodiment of a drive unit according to the invention; Fig. 5 shows a schematic view of a further embodiment of a drive unit according to the invention; Fig. 6 shows a schematic view of a further embodiment of a drive unit according to the invention; Fig. 7 shows a schematic view of a further embodiment of a drive unit according to the invention; Fig. 8 shows an exploded view of the Fig. 2 illustrated drive unit with housing; Fig. 9 a schematic longitudinal sectional view through part of the drive unit of the Figuren 2 and 8; Fig. 10 shows a time sequence diagram of torques over time in a method according to the invention for operating the drive unit; and Fig. 11 shows a schematic representation of a further embodiment of a drive unit according to the invention.

[0105] In Fig. 1 A drive unit 10 for a vehicle such as a bicycle F is shown schematically. The drive unit 10 is integrated into a bicycle frame 12, specifically in the area of ​​a bottom bracket. The drive unit 10 can be integrated into the bicycle frame 12 in such a way that the drive unit 10 forms the bottom bracket.

[0106] The drive unit 10 has a housing 14 which is connected at its outer circumference to a seat tube and a down tube (main tube) of the bicycle frame 12.

[0107] A gear arrangement 16 is accommodated in the housing 14, which is designed to convert a drive movement, which is introduced into the gear arrangement 16 via cranks 18, into a rotation of a chainring or belt wheel 20, with a number of different suitable gear ratios.

[0108] The housing 14 also houses an electric machine 22 which can feed additional drive power into the transmission arrangement.

[0109] The bicycle F is therefore designed as an e-bike or pedelec. Preferably, the electric motor 22 is only activated to provide drive power when torque is also applied via at least one of the cranks 18.

[0110] In Fig. 2 A preferred embodiment of such a drive unit 10 is shown in perspective.

[0111] The drive unit 10 has a drive shaft 26, which is designed as a crankshaft. At its axial ends, the drive shaft 26 has crank plug sections 28 onto which the cranks 18 can be axially mounted.

[0112] The drive unit 10 further comprises a countershaft 30 which is arranged axially parallel to the drive shaft 26.

[0113] A first sub-gearbox 32 connects the drive shaft 26 and the countershaft 30. A second sub-gearbox 34 connects the countershaft 30 to an output shaft 36. The output shaft 36 is arranged coaxially to the drive shaft 26, specifically in the form of a hollow shaft around the drive shaft 26. A spline 38 is provided on the output shaft 36, onto which the chainring or belt pulley 20 can be axially pushed.

[0114] The transmission assembly 16 further includes a machine gear 40, via which drive power from the electric machine 22 can be introduced into the transmission assembly 16. The electric machine 22 is arranged axially parallel to the countershaft 30 and the drive shaft 26. The electric machine 22 is connected to the machine gear 40 via a reduction gear or pre-transmission gear 42.

[0115] The drive shaft 26 is coaxial with an axis A1. The countershaft 30 is coaxial with an axis A2. The electric motor 22 is coaxial with an axis A3. The reduction gear or pre-transmission 42 has a pre-transmission shaft (not further designated) located on an axis A4.

[0116] A camshaft 44 is provided concentrically to the countershaft 30. The camshaft 44 is arranged radially within the countershaft 30 and serves to engage shiftable gear sets of the first sub-transmission 32 and the second sub-transmission 34. The camshaft 44 is coupled to the countershaft 30 via a speed-override gear 46, such that the camshaft 44 generally rotates at the same speed as the countershaft during operation. However, a relative rotation can also be established via the speed-override gear 46 in order to select and engage the individual gear sets.

[0117] The transmission assembly 16 further includes a torque detection device 48 for detecting a muscle-power torque applied to the drive shaft 26. The torque detection device 48 can be connected to a control device (not shown in detail).

[0118] The control device, not shown in detail, is designed to control the electric machine 22 as a function of a torque detected by the torque detection device 48 in order to provide additional drive torque as needed.

[0119] In Fig. 3 A further embodiment of a drive unit according to the invention is shown, which in terms of structure and function generally corresponds to the drive unit 10 of the Fig. 2 Identical elements are therefore identified by the same reference numerals. The differences are essentially explained below.

[0120] As it is in Fig. 3 As can be seen, the drive shaft 26 is coupled to an input shaft 50 via a torsion spring 52 of the torque detection device 48'. The input shaft 50 is arranged as a hollow shaft around the drive shaft 26, axially offset from the output shaft 36.

[0121] A twist angle sensor 56 of the torque detection device 48' detects a relative twist of the input shaft 50 with respect to the drive shaft 26. The twist angle thus measured is preferably proportional to a torque introduced into the drive shaft 26.

[0122] Furthermore, a rotational position sensor or crank position sensor 54 is provided, which detects an absolute rotational position of the input shaft 50.

[0123] The first sub-transmission 32 has a plurality of four shiftable gear sets R1, R2, R3, R4, each of which includes a fixed gear connected in a rotationally fixed manner to the input shaft 50 and an idler gear rotatably mounted on the countershaft 30. The second sub-transmission 34 has a further plurality of gear sets R5, R6, R7. The gear sets of the second sub-transmission each include a fixed gear connected in a rotationally fixed manner to the output shaft 36 and an idler gear rotatably mounted on the countershaft 30.

[0124] The camshaft 44 has a plurality of cams corresponding to the plurality of gear sets of the first and second partial transmissions. Fig. 3 For reasons of clarity, only one switching cam N2 for the wheel set R2 and the switching cam N7 for the wheel set R7 are provided with reference symbols.

[0125] The idler gears of the gear sets R1 to R7 are each connected to the countershaft 30 via switchable freewheels. The switchable freewheels each have switching pawls that can be activated by means of the switching cams (e.g. N2, N7). In the shown relative rotational position of the camshaft 44 with respect to the countershaft 30 of the Fig. 3 The switching cams N2 and N7 activate the switching pawls S2 and S7, so that in the normal forward rotation direction of the drive shaft 26 for driving the bicycle F, the idler gears of the gear sets R2 and R7 are coupled to the countershaft 30. The idler gears of the other gear sets R1, R3, R4, R5, R6, however, are decoupled from the countershaft 30. In the illustration of the Fig. 3 Consequently, a drive torque that is introduced into the drive shaft 26 can be introduced into the input shaft 50 via the torsion spring 52, and from there via the gear set R2 into the countershaft 30. From the countershaft 30, the torque can then be introduced into the output shaft 36 via the gear set R7 of the second partial transmission 34.

[0126] A switching device 60 is provided for the relative rotation of the camshaft 44 with respect to the countershaft 30.

[0127] The shifting device 60 has a planetary gear set arrangement 64 that forms the speed override gearing 46. The planetary gear set arrangement 64 has a first planetary gear set, the sun gear of which is connected to the countershaft 30, the ring gear of which is coupled to the housing 14, and the planet carrier of which is connected to the planet carrier of a second planetary gear set. The sun gear of the second planetary gear set is connected to the camshaft 44. The ring gear 66 of the additional planetary gear set serves to initiate relative rotations between the camshaft 44 and the countershaft 30. The ring gear 66 is connected via a speed adjustment gear 70 to a shift motor 68 in the form of an electric motor. The shift motor 68 is arranged coaxially to an axis A5. The speed adjustment gear 70 has a speed adjustment shaft 71 that lies on an axis A6.A pinion connected to the switching motor 68 is connected to a first fixed gear of the speed adjustment shaft 71. A second fixed gear of the speed adjustment shaft 71 is connected to a drive gear that is rotationally fixedly connected to the ring gear 66. The rotational position of the ring gear 66 can be detected by a switching position sensor 72.

[0128] In the prior art, as mentioned above, such a ring gear 66 was generally operated manually. In the present case, however, gear shifting in the drive unit 10 is performed by actuators, namely via the shift motor 68.

[0129] The electric machine 22 has a rotor, not further designated, whose rotor position can be determined via a rotor position sensor 76.

[0130] The electric machine 22 provides a machine torque TM, which is introduced into a machine shaft 78. The machine torque TM can be combined with a driver torque TF, which is introduced into the drive shaft 26, such that an output torque TA is provided at the output shaft 36, which is introduced into the chainring or pulley 20.

[0131] The transmission assembly 16, as mentioned above, includes a machine gear 40 rotatably mounted on the countershaft 30. The machine shaft 78 is connected to the machine gear 40 via the pre-transmission gear 42. More specifically, the pre-transmission gear 42 includes a pre-transmission shaft 80 located on the axis A4 and connected to the machine shaft 78 via a first constant gear set and having a fixed gear meshing with the machine gear 40.

[0132] The machine gear 40 is connectable to the countershaft 30 via a switchable freewheel. Fig. 3 It is shown that the switchable freewheel is activated, with a freewheel pawl SM connecting the countershaft 30 to the machine gear 40. The freewheel pawl SM can be actuated by means of a switching cam NM of the camshaft 44. The switching cam NM can be formed on a separate section of the camshaft 44, which is connected via a first rotational position-dependent driver 82 to a section of the camshaft 44 that is assigned to the first partial transmission 32. The section of the camshaft 44 on which the switching cam NM is formed is further connected via the second rotational position-dependent driver 84 to a section of the camshaft 44 that is assigned to the second partial transmission 34.

[0133] The drive unit 10 further includes a circuit board 86 on which a control device 88 is formed. The control device 88 receives signals from the various sensors 54, 56, 72, 76 and provides control signals for the power electronics of the electric machine 22 and the shift motor 68. Furthermore, the control device 88 is connected to a switching unit or switch 89, which can be arranged, for example, in the area of ​​a handlebar of the bicycle F and via which switching signals in the form of a switching request or the like can be triggered.

[0134] If such a shift request is received via the shift unit 89, the control device 88 controls the shift motor 68 to perform the desired shifting operation, in which the camshaft 44 is rotated relative to the countershaft 30. This preferably occurs in a coordinated manner, as will be described below.

[0135] The control device 88 is further connected to an authorization unit 90. The authorization unit 90 may, for example, include an input unit for an authorization code, which then generates an authorization signal based on this code and transmits it to the control device 88. Only when a correct authorization signal is received will the control device 88 (and / or the transmission arrangement) be activated.

[0136] The authorization unit 90 can be integrated with the switching unit 89 into an assembly that can be mounted in the area of ​​a handlebar of the bicycle.

[0137] The following operating modes are feasible with the drive unit 10. On the one hand, a purely muscle-powered mode is conceivable. For this purpose, the switchable freewheel of the machine gear 40 is preferably deactivated by rotating the camshaft 44 such that the switching cam NM moves the freewheel switching pawl SM into a deactivation position, so that drive power of the electric motor 22 can no longer be fed into the countershaft 30.

[0138] For a Pedelec operating mode, however, the freewheel pawl SM is activated. A torque TF introduced into the drive shaft 26 by muscle power is detected via the torque detection device 48. The control device then controls the electric motor 22 such that it additionally provides an electric drive torque TM, preferably depending on various assistance modes (Eco, Normal, or Turbo, to name a few examples). The torque TM is adjusted such that a total output torque TA is provided in the area of ​​the output shaft 36, which is composed of the rider torque TF and an electric drive torque TM, which typically represents a value of 0.5 to 4 times the rider torque TF.

[0139] In some countries, electric motor assistance is limited to a certain speed threshold, for example, 25 km / h. If the driver sets a higher vehicle speed using muscle power, the countershaft 30 overtakes the machine gear 40. If the resulting clicking of the switchable freewheel is perceived as annoying, the control device 88 can deactivate the freewheel.

[0140] The control device 88 can also activate the switchable freewheel with the switching pawl SM, for example, only when a valid authorization signal has been detected.

[0141] If an inadmissible torque is provided by the electric machine 22 in a fault condition, the control device 88 can also deactivate the switchable freewheel with the switching pawl SM.

[0142] If a shift request is detected via the switching unit 89, the control device 88 initiates a shift operation of at least one of the gear sets by means of the switching device 60 such that this shift operation is carried out during a time period in which a muscle power torque TF acting periodically on a drive shaft is minimal. Alternatively or additionally, upon detection of such a shift request, a torque provided by the electric machine is initially increased for a first short time period in order to at least tension the transmission arrangement, and then the torque provided by the electric machine is quickly reduced in order to place the transmission arrangement into a load-free state for a second short time period. The switching device is timed such that a shift of the gear set occurs within this second short time period.

[0143] In the Figuren 4 bis 7 Further embodiments of drive units are shown which, in terms of structure and function, generally correspond to the drive unit 10 of the Fig. 3 Identical elements are therefore identified by the same reference numerals. The differences are essentially explained below.

[0144] For the drive unit 10' of the Fig. 4 The rotor of the electric machine 22 is connected to the machine shaft 78' via a clutch or freewheel that can be switched by means of the control device 88. In this case, the machine gear 40' is connected in a rotationally fixed manner to the countershaft 30. The camshaft 44' can be designed as a continuous shaft, or a rotationally position-dependent driver 82' can be provided between a section assigned to the first partial transmission 32 and a section assigned to the second partial transmission 34.

[0145] The disconnect clutch 92 can be a normally open clutch that is closed by an actuator (not shown in detail) when the electric machine 22 is to provide drive torque. Alternatively, the disconnect clutch 92 can also be a normally closed clutch that is opened by an actuator when needed. Such an actuator is typically connected to the control device 88. The actuator can be, for example, a solenoid actuator or another actuator.

[0146] In Fig. 4 It is further shown that the switching position sensor 72' is connected to a rotor of the switching motor 68. This embodiment of a switching position sensor 72 is structurally simple to implement. However, the switching position may be influenced by a play in the speed adjustment gear 70, so that detection of the switching position of the ring gear 66 via a switching position sensor 72, as shown in Fig. 3 shown is preferred.

[0147] In Fig. 5 another embodiment of a drive unit 10" is shown, which is based on the embodiment of the Fig. 3 based.

[0148] Instead of the switchable freewheel with the switching pawl SM, the machine gear 40" is connected via a non-switchable freewheel 98 to an intermediate shaft 96, which is arranged coaxially around the countershaft 30. The intermediate shaft 96 is connected in a rotationally fixed manner to the idler gear of one of the gear sets of the first sub-transmission (or the second sub-transmission). The non-switchable freewheel can also be attached to the end face of the machine gear 40". In this case, the freewheel can act directly between the machine gear 40" and the idler gear of one of the gear sets of the first sub-transmission (or the second sub-transmission). The intermediate shaft 96 can be omitted in this case. In this case, the intermediate shaft 96 is connected to the idler gear of gear set R1.

[0149] Furthermore, the fixed gears of the gear sets R1 to R4 of the first partial transmission 32 are fixed to a fixed gear shaft 100, which is arranged coaxially around the input shaft 50". The fixed gear shaft 100 is coupled to the input shaft 50" via a further non-switchable freewheel 102. This ensures that no inadmissible torques are transmitted from the electric machine 22 to the drive shaft 26, which, as in the previous embodiments, is coupled to the input shaft 50" via a torsion spring 52.

[0150] In Fig. 5 Furthermore, a variant of a switching position sensor 72" is shown, which is arranged on a sensor shaft 104, which lies on an axis A7. The sensor shaft 104 is connected to a fixed gear, which is in engagement with the gear, to which a drive torque of the switching motor 68 is also introduced and which is connected in a rotationally fixed manner to the ring gear 66 of the speed superposition gear 46. In general, a switching position sensor can also be used in the embodiment of the Fig. 5 However, it can be designed in any of the other ways described above, for example without a sensor shaft or in one piece.

[0151] The sensor shaft 104 can be manufactured from plastic together with a fixed gear attached to it, since it does not have to transmit any torque.

[0152] In Fig. 6 A further embodiment of a drive train is shown, which is based on the embodiment of the Fig. 5 In the drive unit 10‴, an idler gear is rotatably mounted on the pre-transmission shaft 80‴, which idler gear meshes with the machine gear 40‴. The idler gear of the pre-transmission shaft 80‴ is coupled to the pre-transmission shaft 80 via a non-switchable freewheel 98‴. The machine gear 40‴ is rotatably mounted on the countershaft 30 and meshes with a fixed gear 105 that is attached to the fixed gear shaft 100. Consequently, drive power of the electric machine 22 can be introduced into the fixed gear shaft 100 and from there via the first sub-transmission 32 and the second sub-transmission 34 to the output shaft 36.

[0153] As with the design of the Fig. 5 The fixed gear shaft 100 is coupled to the input shaft 50" via a second non-switchable freewheel 102.

[0154] In Fig. 7 another embodiment of a drive unit 10 IV< is shown, which is based on the embodiment of the Fig. 3 and6 based. In the drive unit 10 IV<, the pre-transmission 42 IV< includes a planetary gear set 106, which has three members, one of which (in this case the ring gear) is connected to the housing 14. Another member is connected to the machine shaft 78 (in this case the sun gear). A third member (in this case the planet carrier) is connected to a pre-transmission shaft 80 IV<, which in this case is arranged as a hollow shaft 80 IV< around the machine shaft 78. The pre-transmission shaft 80 IV< is connected to a fixed gear, which engages with an intermediate gear 109, which is fixed to a secondary shaft 108. The secondary shaft 108 is in Fig. 7 as coaxial with the countershaft 30. In a preferred embodiment, however, the auxiliary shaft 108 is arranged axially parallel to the countershaft 30. The intermediate gear 109 is in engagement with a machine gear 40 IV<, which is rotatably mounted on an intermediate shaft / fixed gear shaft 100, which is arranged coaxially with the input shaft 26. The fixed gear shaft 100 is coupled to the machine gear 40 IV< via a non-switchable freewheel 98 IV<. Furthermore, the fixed gear shaft 100 is coupled to the input shaft 50" via a second non-switchable freewheel 102, as in the embodiments of the Fig. 5 and 6 .

[0155] Functionally, the design corresponds to the Fig. 7 consequently that of the Fig. 6 .

[0156] In Fig. 8 is an exploded view of a drive unit 10 V<, which is structurally similar to the drive unit 10 of the Fig. 2 and 3It can be seen that the housing 14 has a base housing 110, as well as a first housing cover 112 and a second housing cover 114.

[0157] An area between the base housing 110 and the first housing cover 112 is designed to accommodate the circuit board 86 with the rotor position sensor 76 and the switching position sensor 72 secured thereto. The space between the base housing 110 and the first housing cover 112 is preferably fluid-free. Suitable seals are provided in the base housing 110 for this purpose.

[0158] The first housing cover 112 and the second housing cover 114 are placed on the base housing 110 in the axial direction.

[0159] The gear assembly 16 is accommodated together with the electric machine 22 in a space formed by the base housing 110 and the second housing cover 114. However, the electric machine 22 is preferably accommodated therein in such a way that at least the stator or its connections (preferably also the rotor) are sealed off from a fluid space formed by the base housing 110 and the second housing cover 114. The stator of the electric machine 22 is contacted with the printed circuit board 86 via plug contacts. The rotor of the electric machine 22 preferably has permanent magnets that do not require electrical contact. However, a part of the rotor position sensor 76 is preferably provided on the rotor of the electric machine 22 and interacts with the other part on the printed circuit board 86.

[0160] In Fig. 8 Further shown is a torque detection device 48, which includes a permanent magnet 120, which is fixed, for example, to the input shaft 50 or to the drive shaft 26. Furthermore, the torque detection device 48 has at least one Hall sensor 122, which is fixed to a sensor unit 118 arranged coaxially to the drive shaft 26 and connected to a control device 88 via indicated cables.

[0161] In Fig. 8 It can also be seen that the switching position sensor 72 can be constructed in a similar manner as in Fig. 5 shown, with a sensor shaft 104 arranged on an axis A7.

[0162] Fig. 9 shows a longitudinal sectional view of the drive unit 10 V< . It can be seen here that the shaft arrangement with the drive shaft 26 and the input shaft 50 is rotatably mounted by means of a first bearing 124 and a second bearing 126, wherein the first bearing 124 is arranged in the region of the base housing 110 and wherein the second bearing 126 is arranged in the region of the second housing cover 114.

[0163] The countershaft 30 is rotatably supported at least by means of a third bearing 128 which is formed on the second housing cover 114, and preferably by means of a needle bearing (not further designated) on the axially opposite side.

[0164] Fig. 10 shows a time sequence diagram of a torque over time.

[0165] In Fig. 10 A switching process is shown that can occur under load.

[0166] Fig. 10 shows first that a torque TF provided by a driver is applied approximately sinusoidally to the drive shaft 26, with a period P.

[0167] Furthermore, it can be seen that before a gear shift, the electric motor provides a torque TM that is approximately synchronous with the driver torque TF and, for example, accounts for approximately 70% to 80% of the driver torque TF. However, in other embodiments, the torque TM can also be significantly greater.

[0168] At a time t 1, a switching request is detected by the control device, for example via the switching unit 89.

[0169] In this case, the torque TM of the electric machine is first increased, preferably synchronously with a maximum of the driver torque TF .

[0170] The torque is increased for a first time period E1, for example, from a time t1 to a time t4. At a time t3, a maximum of the driver torque TF is reached.

[0171] A gear shift is to occur at time t 7 . At time t 4 , the torque TM of the electric motor is then reduced such that it reaches a minimum value T M-MIN at time t 6 , i.e., it is not reduced to 0. This time t 6 occurs slightly before the minimum driver torque TF . The torque reduction from time t 4 onward is therefore timed such that time t 6 occurs shortly before the planned gear shift time t 7 .

[0172] After the gear shift, starting at time t8, the electric drive torque TM can be increased again and raised to a normal assistance level that existed before the gear shift. This is reached at time t10.

[0173] For the second short period of time E 2 the torque is therefore reduced.

[0174] Because the torque was initially increased for the time period E 1 , so that the drivetrain was tensioned overall, and the torque was then quickly or abruptly reduced, the drivetrain is relaxed overall, resulting in a load-free state. This occurs, for example, in a window from approximately t 5 to t 9 . Preferably, a shifting operation occurs within a time window from t 6 to t 8 , in particular at a time t 7 .

[0175] The shifting process can therefore occur at a time when the drivetrain is essentially load-free. Consequently, shifting can occur under load.

[0176] Increasing the torque TM does not affect the vehicle's speed due to inertia. Similarly, decreasing the torque TM does not affect the vehicle's handling, also due to inertia.

[0177] The driver is, so to speak, unaware that this short-term increase in torque and subsequent reduction in torque has taken place.

[0178] In Fig. 11 A further embodiment of a drive unit 10 VI< is shown, which is functionally based on the drive unit 10' of the Fig. 4 . Identical elements are therefore identified by identical reference numerals. The differences are explained below.

[0179] In Fig. 11 It is shown that a cooling arrangement 130 can be provided for cooling power electronics on the circuit board 86 and / or the stator 22S of the electric machine 22.

[0180] The cooling arrangement 130 initially utilizes the fact that a fluid sump 132 is located in the housing 14, which lubricates the gear sets of the first and second partial transmissions by means of splash lubrication. The fluid sump 132 has a fluid level 134. A fluid pump 136 is arranged below the fluid level 134. This fluid pump is driven by an electric motor, for example, controlled via the control device 88, or driven by coupling to an existing shaft.

[0181] The fluid pump 136 pumps fluid into a fluid line 138, which leads to a plurality of cooling points and is finally returned to the fluid sump 132.

[0182] In a first cooling point 140 of the housing, the fluid can be cooled from the outside, for example, by an air flow (not shown in detail) into the housing 14.

[0183] At a second cooling point 142, heat from the stator 22S of the electric machine 22 is transferred to the fluid flowing in the fluid line 138.

[0184] For this purpose, the stator is provided with cooling channels between the windings or winding heads. Alternatively, the housing area around the stator can also be provided with cooling channels.

[0185] At a third cooling point 144, heat is transferred from the circuit board 86 to the fluid flowing in the fluid line 138.

[0186] At a fourth cooling point 146, the fluid line 138 can pass through a heat sink 148, via which heat contained in the fluid is released again before it is fed back into the fluid sump.

[0187] Furthermore, in Fig. 11 schematically indicated that a fluid deflector plate 150 can be provided in the housing 14, via which fluid 152 thrown up by the wheel sets can be directed onto heat sources, for example onto the circuit board 86 or a heat sink connected thereto, and / or for example onto stator winding heads of the stator 22S or onto heat sinks connected thereto. Bezugszeichenliste

[0188] 10Drive unit 12Bicycle frame 14Housing 16Gear assembly 18Cranks 20Chainring / belt pulley 22Electric machine 26Drive shaft / crankshaft 28Crank plug sections 30Countershaft 321st partial transmission 342nd partial transmission 36Output shaft 38Spline for 20 40Machine gear 42Reduction gear / first gear 44Camshaft 46Speed ​​superposition gear 48Torque sensing device 50Input shaft (16) 52Torsion spring (48) 54Torsion angle sensor (48) 56Rotational position sensor / crank position sensor 60Shift device 64Planetary gear set assembly 66Ring gear 68Shift motor 70Speed ​​adjustment gear 71Speed ​​adjustment shaft 72Switching position sensor 76Rotor position sensor 78Machine shaft 79Machine pinion 80Pre-transmission shaft 81Gear 821st rotational position-dependent driver 842nd rotational position-dependent driver 86Printed circuit board 88Control device 89Switching unit 90Authorization unit 91Authorization signal 92Separating clutch 96Intermediate shaft 981.Non-switchable freewheel 100 Intermediate shaft / fixed gear shaft 102 2nd non-switchable freewheel 104 Sensor shaft 105 Fixed gear 106 Planetary gear set (42) 108 Countershaft 109 Intermediate gear (108) 110 Base housing 112 1st housing cover 114 2nd housing cover 118 Sensor unit (48) 120 Permanent magnet 122 Hall sensor 124 1st bearing 126 2nd bearing 128 3rd bearing 130 Cooling arrangement 132 Fluid sump 134 Fluid level 136 Fluid pump 138 Fluid line 140 1st cooling point 142 2nd cooling point 144 3rd cooling point 146 4th cooling point 148 Heat sink 150 Fluid deflector 152 Fluid F Bicycle (E-Bike) A1-A6 axles R1-R4 first switchable wheel sets (32) R5-R7 second switchable wheel sets (34) S1-S7 pawls (R1-R7) N1-N7 switching cams (R1-R7) SM freewheel switching pawl (40) NM switching cams (40) TF driver torque TM electric machine torque TM-MIN minimum torque of the electric machine TA output torque TF drive torque at 20 P period TF E1 first time period E2 second time period.

Claims

1. Gear arrangement (16) for a vehicle (F), in particular for a vehicle which can be driven using muscular force, such as a bicycle (F), having - an input shaft (50), - a layshaft (30), - an output shaft (36) which can be connected to a drive wheel (20) of the vehicle (F), - a plurality of shiftable first gear wheel sets (R1-R4) by means of which the input shaft (50) and the layshaft (30) can be connected, and which are each associated with at least one gear stage, - a machine gear (40) which is connected or can be connected to one of the shafts and into which the drive torque (TM) of an electric machine (22) can be introduced, wherein the electric machine (22) is connected to the machine gear (40) by means of a lead gear mechanism (42), characterised in that wherein the lead gear mechanism (42) is arranged so as to axially overlap with at least one gear wheel set of the first gear wheel sets and / or is arranged so as to axially overlap with at least one gear wheel set of the second shiftable gear wheel sets.

2. Gear arrangement according to claim 1, wherein the machine gear (40) is connected by means of a free wheel (SM) to one (30) of the shafts (50, 30, 36).

3. Gear arrangement according to claim 1, wherein the machine gear (40) is securely connected to the layshaft (30), wherein the electric machine (22) can be connected to the machine gear (40) by means of a separating clutch (92) or a free wheel.

4. Gear arrangement according to claim 1, wherein the machine gear (40) is connected by means of a free wheel (SM) to an intermediate shaft (96) which is securely connected to an idler wheel of a gear wheel set (R1) of the first gear wheel sets (R1-R4), which idler wheel is rotatably supported on the layshaft (30).

5. Gear arrangement according to claim 1, wherein the machine gear (40) is connected or can be connected to an intermediate shaft (100; 96IV) which is arranged coaxially with respect to the input shaft (50), wherein the intermediate shaft (100; 96IV) preferably is connected to the input shaft (50) by means of a shiftable free wheel (102) or a separating clutch.

6. Gear arrangement according to any one of claims 1 to 5, characterised in that the input shaft (50) is coupled to a drive shaft (26) by means of a spring arrangement (52) of a torque detection device (48).

7. Gear arrangement according to any one of claims 1 to 6, wherein the electric machine (22) is connected to the machine gear (40) by means of a lead gear mechanism (42), wherein the lead gear mechanism (42) has an intermediate wheel (109) which is rotatably supported on an auxiliary shaft (108) which is arranged offset in a parallel manner with respect to the input shaft (50) and the layshaft (30).

8. Gear arrangement according to any one of claims 1 to 7, wherein the first gear wheel sets (R1-R4) form a first part-gear mechanism (32), wherein at least one second shiftable gear wheel set (R5-R7) connects the layshaft (30) and the output shaft (36) and forms a second part-gear mechanism (34), wherein the at least one second gear wheel set (R5-R7) is associated with at least one gear stage and wherein the machine gear (40) is arranged in an axial direction between the first part-gear mechanism (32) and the second part-gear mechanism (34).

9. Gear arrangement according to any one of claims 1 to 8, characterised in that the wheel sets (R1 to R7) of the gear arrangement (16) are arranged in a housing (14) which defines a fluid sump (132) for producing a lubrication for the wheel sets (R1 to R7), wherein a heat source (86; 22S) is arranged in the housing (14) and wherein the arrangement of the heat source (86; 22S) in the housing (14) is selected in such a manner and / or the housing (14) is constructed in such a manner that the heat source (86; 22S) is subjected to the flow of fluid (152) which is removed, in particular thrown up, from the fluid sump (132) during operation.

10. Gear arrangement according to any one of claims 1 to 9, characterised in that the wheel sets (R1 - R7) of the gear arrangement (16) are arranged in a housing in which a fluid sump (132) is arranged for lubrication and / or cooling, wherein a fluid pump (136) draws from the fluid sump (132) fluid (152) which is used to cool the heat source (86; 22S).

11. Drive unit (10) for a vehicle (F), in particular for a vehicle which is driven with muscular force, such as a bicycle, having a gear arrangement (16) according to any one of claims 1 to 10 and having an electric machine (22) which is connected to the machine gear (40) of the gear arrangement (16), wherein the drive unit preferably comprises (i) a control device (88) for controlling a shifting apparatus (60) for the gear wheel sets (R1-R7) and / or for controlling the electric machine (22), and (ii) a sensor arrangement for detecting at least one status variable of the drive unit (10).

12. Drive unit according to claim 11, wherein the sensor arrangement comprises a rotor position sensor (76) for detecting a rotation position of a rotor (22R) of the electric machine (22) and / or a shifting position sensor (72) and / or a speed sensor (56) for detecting a speed of the input shaft (50) and / or a rotation position sensor (54) for detecting a relative rotation position of the input shaft and / or a crank position sensor (56) for detecting a rotation position of cranks (18) which are connected to a drive shaft (26) and / or a torque sensor (54) for detecting a muscular force torque (TF) which is introduced into a drive shaft (26).

13. Drive unit according to any one of claims 11 to 12, wherein the control device (88) is constructed and configured to carry out a shifting operation of at least one of the wheel sets (R1-R7) by means of the shifting apparatus (60) during a time period (E2), within which a muscular force torque (TF) acting periodically on a drive shaft (26) is at a minimum.

14. Drive unit according to any one of claims 11 to 13, wherein the control device (88) is constructed and configured, when a wish to shift is detected, to initially increase a torque (TM) provided by the electric machine (22) for a first short time period (E1) in order to tension at least the gear arrangement (16), and subsequently to rapidly decrease the torque (TM) provided by the electric machine (22) in order to place the gear arrangement (16) for a second short time period (E2) in a load-free state, wherein the shifting apparatus (60) is temporally controlled in such a manner that a shifting of a gear wheel set (R1-R7) falls within this second short time period (E2), wherein it is preferably provided that the control device (88) is constructed and configured so that the first short time period (E1) overlaps temporally with a time period in which a muscular force torque (TF) acting periodically on a drive shaft (26) is at a maximum, and / or wherein the control device (88) is constructed and configured so that the second short time period (E2) corresponds to the time period (E2) within which the muscular force torque (TF) acting periodically on the drive shaft (26) is at a minimum, and / or wherein it is preferably provided that the electric machine (22) can be connected to one of the shafts by means of a separating clutch (92) or a shiftable free wheel, wherein the separating clutch (92) or the free wheel is activated where required so that (a) a sudden deactivation of a torque (TM) provided by the electric machine (22) is possible and / or (b) a deactivation is carried out when a control device (88) does not obtain any authorisation signal (91) and / or (c) no clicking noise can be heard when the electric machine (22) is shifted off.

15. Method for operating a drive unit according to any one of claims 11 to 14, wherein - a shifting operation of at least one of the wheel sets (R1-R7) is carried out by means of the shifting apparatus (60) during a time period (E2) in which a muscular force torque (TF) which acts periodically on a drive shaft (26) is at a minimum; and / or wherein, - when a wish to shift is detected, a torque (TM) provided by the electric machine (22) is initially increased for a first short time period (E1) in order to tension at least the gear arrangement (16), and, subsequently, the torque (TF) provided by the electric machine (22) is rapidly reduced in order to move the gear arrangement (14) for a second short time period (E2) into a load-free state, wherein the shifting apparatus (60) is temporally controlled in such a manner that a shifting of a gear wheel set (R1-R7) falls within this second short time period (E2).