Bottom bracket gearbox for a bicycle, bottom bracket and bicycle

Abstract

Bottom bracket gearbox for a bicycle, comprising at least four shifting elements, a drive shaft (1), a first planetary gear set (PS1) which is operatively connected to the drive shaft (1), a second planetary gear set (PS2) which is operatively connectable to the drive shaft (1), and an output shaft (2), wherein the drive shaft (1) is non-rotatably connected to a ring gear of the first planetary gear set (PS1) and the output shaft (2) is non-rotatably connected to a web of the first planetary gear set (PS1), characterized in that the bottom bracket gearbox comprises an electric machine (8) which is connected downstream of at least one of the planetary gear sets (PS1, PS2; PS3) in terms of drive technology.

Description

[0001] The invention relates to a bottom bracket gearbox for a bicycle, comprising at least four shifting elements, a drive shaft, a first planetary gear set which is operatively connected to the drive shaft, a second planetary gear set which can be operatively connected to the drive shaft, and an output shaft.

[0002] Furthermore, the invention relates to a bottom bracket with such a bottom bracket gearbox. In addition, the invention relates to a bicycle with the bottom bracket or the bottom bracket gearbox.

[0003] A variety of transmissions suitable for bicycle use are known from the prior art. For example, US Patent 2011 / 0177911A1 discloses a transmission comprising three planetary gear sets connected in series, each with a high-speed reduction. This transmission has a total of seven planetary gear levels, including numerous stepped planetary gears, resulting in a very complex design.

[0004] WO 2012 / 093 214 A2 concerns a gearbox for bicycles, consisting of a coaxial gear system with two sun gears, several planet gears of different sizes, a rotating planet carrier and a switching device for selecting different gear ratios.

[0005] DE 11 2010 002 286 T5 relates to a multi-stage gearbox with a stationary center shaft, a coaxially rotatable input element and a hub, a planetary gear set with at least two planetary gear pairs, an axial coupling for selective connection of components, a coupling assembly for controlling the sun gears and a gearbox shaft with a hollow section and through-holes for selecting the direction of rotation and transmission ratios between the input and the hub.

[0006] US 2007 / 0275811A1 relates to an automatic transmission arrangement with several adjacent, speed-dependent coupling transmission units, each generating a partial transmission ratio and together providing an overall transmission ratio for forward travel.

[0007] JP H04 - 300 794 A relates to an automatic bicycle transmission with a central sun gear, two rotating planetary gears, an external sprocket, rotating bearing plates, a freewheel clutch and a locking mechanism for load-dependent gear selection with automatic switching between direct drive and reduction.

[0008] DE 12 76 488 A relates to a multi-speed hub for bicycles with two independently operable shifting systems, as well as several planetary gear sets which activate various output devices via axially displaceable shifting means and ratchet freewheel clutches and enable flexible coupling of the gear components to generate different transmission ratios.

[0009] DE 10 2012 200 829 A1 relates to a bicycle gearbox with a multi-speed gearbox hub in which a pawl is mechanically activated or deactivated via a cam surface and a cam follower in order to control the torque transmission path between the input and output sides and to implement the switching operations.

[0010] US 2011 / 0241306A1 relates to a bicycle transmission arrangement with two coaxial planetary gears connected to each other via a rotating transmission element to transmit torque between the input and output sides.

[0011] GB 2 474 830 A relates to a bicycle gear assembly with a central sun gear, several planetary gear units for variable transmission, a deflecting gear for adjusting the direction of rotation and a spring-loaded clutch for selectively activating individual transmission stages.

[0012] KR 100 361 581 B1 relates to a bicycle gearbox with a forward drive unit in which a pedal axle is connected via a housing to a drive sprocket, which enables constant forward travel both when the pedals are moved forward and backward.

[0013] WO 2013 / 191 572 A1 concerns a multi-stage planetary gear unit, as well as clutches for selective torque transmission and a freewheel clutch for continuous power transmission between the crank mechanism and the output gear during gear changes.

[0014] The object of the invention is therefore to provide a bottom bracket gearbox that has a low construction effort.

[0015] The problem is solved by the subject matter with the features of the independent patent claims. Advantageous further developments are evident from the dependent claims.

[0016] The bottom bracket gearbox according to the invention, in which the drive shaft is rotationally fixed to a ring gear of the first planetary gear set and in which the drive shaft is rotationally fixed to a web of the first planetary gear set, has the advantage that a 4-speed gearbox can be provided that does not require stepped planetary gears. The gearbox has a simple and compact design, and the bottom bracket gearbox can be assembled quickly. Furthermore, the bottom bracket gearbox has good efficiency and can be manufactured cost-effectively. The bottom bracket gearbox according to the invention also has the advantage that it is suitable for bicycle applications, particularly in conjunction with a pre- or post-shifting group described in more detail below.

[0017] The term "shaft" does not exclusively refer to a cylindrical, rotatably mounted machine element for transmitting torques, but rather also includes general connecting elements that connect individual components or elements, in particular connecting elements that non-rotatably join several elements together.

[0018] The first planetary gear set can be a plus planetary gear set and / or the second planetary gear set can be a minus planetary gear set. A minus planetary gear set corresponds to a planetary gear set with a bridge on which the planet gears are rotatably mounted, a sun gear and a ring gear, wherein the teeth of at least one of the planet gears mesh with the teeth of both the sun gear and the ring gear, causing the ring gear and the sun gear to rotate in opposite directions when the sun gear rotates with the bridge stationary.

[0019] In contrast, a plus planetary gear set differs from a minus planetary gear set in that the plus planetary gear set has inner and outer planet gears that are rotatably mounted on the carrier. The teeth of the inner planet gears mesh with the teeth of the sun gear on one side and with the teeth of the outer planet gears on the other. The teeth of the outer planet gears also mesh with the teeth of the ring gear. This means that when the carrier is stationary, the ring gear and the sun gear rotate in the same direction.

[0020] In a particular embodiment, a sun gear of the second planetary gear set can be non-rotatably connected to the drive shaft by means of a first switching element (one of at least four switching elements). Furthermore, the sun gear can be non-rotatably connected to a gearbox housing by means of a second switching element (one of at least four switching elements). A web of the second planetary gear set can be non-rotatably connected to a sun gear of the first planetary gear set. A ring gear of the second planetary gear set can be non-rotatably connected to the gearbox housing by means of a third switching element (one of at least four switching elements). Furthermore, the ring gear of the second planetary gear set can be non-rotatably connected to the output shaft by means of a fourth switching element (one of at least four switching elements).

[0021] The gearbox housing can be an integral part of the bottom bracket housing, i.e., it can be manufactured as a single piece with the bottom bracket housing. Alternatively, the gearbox housing can be separate from the bottom bracket housing and, when the bottom bracket gearbox is assembled, located within a cavity of the bottom bracket housing. The gearbox housing can be designed and positioned so that it does not rotate during operation of the bottom bracket gearbox, but remains stationary.

[0022] The first and second planetary gear sets can be arranged such that the drive shaft does not extend through a plane containing the second planetary gear set. Alternatively, the first and second planetary gear sets can be arranged such that the drive shaft extends through the plane containing the second planetary gear set. In particular, this plane can contain the ring gear, the bridge, and the sun gear of the second planetary gear set. As a result, the arrangement of the first and second planetary gear sets relative to each other can depend on the available installation space in the bottom bracket gearbox and / or the bottom bracket shell.

[0023] The bottom bracket gearbox according to the invention has the advantage that the switching elements are easily accessible for an actuator. The second and third switching elements can be designed as brakes and / or arranged in a radially outer area of ​​the bottom bracket gearbox, which simplifies accessibility. The first and fourth switching elements can each be designed as clutches or freewheels. If the first and fourth switching elements are each designed as freewheels, no switching mechanism or actuator is advantageously required. Furthermore, the first and fourth switching elements only need to provide low support torques, so the freewheels can be made small.

[0024] The drive shaft can be connected to the bottom bracket crank axle in a rotationally fixed manner. In this design, the output shaft can be connected to a traction element, such as a chainring or pulley, in a rotationally fixed manner. When the bottom bracket gearbox is used in the bicycle, a torque applied to the traction element can be transmitted to a rear wheel via a traction element, such as a chain or belt.

[0025] The result is a bottom bracket gearbox in which exactly four gears can be provided by exactly two planetary gear sets and / or exactly four shifting elements. The first gear can be a direct drive, i.e., have a gear ratio of 1. The remaining gears can have a higher gear ratio, i.e., a gear ratio less than 1.

[0026] In a special design, the bottom bracket gearbox can have a third planetary gear set that is operatively connected to the first and / or second planetary gear set. The third planetary gear set can be positioned upstream or downstream of the first and second planetary gear sets. The third planetary gear set can also be a negative planetary gear set.

[0027] An element of the third planetary gear set can be non-rotatably connected to another element of the third planetary gear set by means of a fifth switching element. With the fifth switching element closed, the third planetary gear set is locked, thus exhibiting a gear ratio of 1. It is particularly advantageous if the ring gear of the third planetary gear set can be non-rotatably connected to the sun gear of the third planetary gear set by means of the fifth switching element. This is advantageous because, in this case, the fifth switching element requires only minimal supporting torque. Alternatively, it is of course possible to arrange the fifth switching element such that a web of the third planetary gear set can be non-rotatably connected to a sun gear or a ring gear of the third planetary gear set by means of the fifth switching element.

[0028] The ring gear of the third planetary gear set can be connected to the gearbox housing in a rotationally fixed manner by means of a sixth switching element. The sixth switching element can be designed as a brake and the fifth switching element as a clutch or freewheel.

[0029] In a special design, the third planetary gear set can be arranged upstream of the first and second planetary gear sets in a pull-type bottom bracket gearbox, thus forming a pre-selector group. In this design, the input shaft, the first planetary gear set, the second planetary gear set, the output shaft, and the four shift elements form a main assembly. A web of the third planetary gear set can be non-rotatably connected to the bottom bracket crank axle via another input shaft, and a sun gear of the third planetary gear set can be non-rotatably connected to the input shaft. In this design, the output shaft can also be non-rotatably connected to the pull-type carrier.

[0030] Alternatively, a design is possible in which the third planetary gear set, when the bottom bracket gearbox is driven by a pulley system, is connected downstream of the first and second planetary gear sets, thus forming a downstream group. In this design, the input shaft, the first planetary gear set, the second planetary gear set, the output shaft, and the four shift elements form a main group. The output shaft can be non-rotatably connected to the hub of the third planetary gear set, and the sun gear of the third planetary gear set can be non-rotatably connected to another output shaft. This second output shaft can be non-rotatably connected to the pulley carrier. In this design, the input shaft can also be non-rotatably connected to the bottom bracket crank axle.

[0031] The pre-selector or post-selector group can provide exactly two gears and / or have exactly two shift elements, namely the fifth and sixth shift elements. The first gear can be a direct drive, and the second gear can be a high-ratio transmission. The pre-selector or post-selector group can have exactly one planetary gear set, namely the third planetary gear set. Furthermore, the third planetary gear set does not have a stepped planetary gear. A range gearbox can be implemented when the pre-selector or post-selector group is combined with the main group.

[0032] Regardless of whether the bottom bracket gearbox has a pre-set or post-set gear group in addition to the main group, all variants result in the same gear ratio range; that is, the overall function of the bottom bracket gearbox is the same in all variants. Differences lie in the speed and torque ratios occurring at the individual planetary gear sets. Since both the pre-set or post-set gear group and the main group have direct drive as their first gear, the torque load is similar in all variants. Greater differences arise in the speeds, as the planetary gear sets located further downstream in the power flow operate at a higher input speed in some gears.

[0033] The clutches or brakes used in the bottom bracket gearbox can be designed as positive-locking or friction-locking mechanisms. If the aforementioned shifting elements are designed as freewheels, it is advantageous that, on the one hand, the main group and / or, on the other hand, the upstream or downstream group do not lock, in order to prevent the bottom bracket gearbox from locking up when the direction of rotation is reversed at the drive or output. This can be achieved by designing the fifth shifting element of the upstream or downstream group and / or the second and third shifting elements of the main group as a one-way brake, such as a switchable freewheel brake.

[0034] As a result, an 8-speed gearbox can be achieved by coupling the main group, which provides four gears, with a pre- or post-group, each providing two gears. The bottom bracket gearbox is advantageous because eight gears can be achieved with exactly three planetary gear sets, resulting in a compact design. Furthermore, the bottom bracket gearbox offers suitable values ​​for stationary gear ratios, allowing the planetary gear sets to have a small diameter. Another advantage is that exactly three shift elements can be configured as brakes. The remaining shift elements can be configured as freewheels. This is advantageous because at least one, and specifically exactly three, actuators are required to operate the three shift elements configured as brakes.

[0035] The bottom bracket gearbox incorporates an electric motor that is connected downstream of the first, second, and / or third planetary gear set, i.e., at least one planetary gear set. Specifically, the electric motor can be operatively connected to the output shaft or the subsequent output shaft. This downstream connection of the electric motor offers the advantage that the planetary gear sets are not subjected to the torque provided by the electric motor. Furthermore, the electric motor provides assistance to the cyclist. This eliminates the need for fine gear increments, as the electric motor significantly reduces the impact of muscle power on propulsion.

[0036] The electric machine consists at least of a rotationally fixed stator and a rotatably mounted rotor which, in motor operation, is designed to convert electrical energy into mechanical energy in the form of speed and torque, and in generator operation, to convert mechanical energy into electrical energy in the form of current and voltage.

[0037] The electric motor can be arranged offset from a central axis of the bottom bracket gearbox and / or the bottom bracket crankshaft, particularly in the radial direction. Specifically, a central axis of the electric motor can run parallel to a central axis of the bottom bracket gearbox. This offers the advantage that the electric motor can be located in an area of ​​the bottom bracket gearbox and / or the bottom bracket shell where sufficient space is available to accommodate it. Furthermore, the inner diameter of the electric motor can be freely chosen, since the bottom bracket crankshaft, which is not part of the bottom bracket gearbox, does not pass through the electric motor.

[0038] The connection of the electric machine to the output shaft or further output shafts can be achieved via a chain drive and / or belt drive and / or a spur gear drive and / or a reduction gear drive. Furthermore, a freewheel can be incorporated into the power flow between the electric machine and the output shaft or further output shaft. The freewheel offers the advantage that, when operating without the electric machine, no losses are caused by the rotating rotor of the electric machine.

[0039] A bottom bracket with the bottom bracket gearbox according to the invention is particularly advantageous, wherein the drive shaft or the further drive shaft is rotationally fixed to the bottom bracket crankshaft. The bottom bracket can have a bottom bracket housing, with the bottom bracket gearbox arranged in a cavity of the bottom bracket housing. The bottom bracket gearbox can be modular in design. Therefore, the bottom bracket gearbox can be inserted into or removed from the cavity as a whole. A bicycle with the bottom bracket gearbox or the bottom bracket is particularly advantageous.

[0040] The invention is schematically represented in the figures and is described below with reference to the figures, whereby identical or equivalently acting elements are mostly provided with the same reference numerals. This shows: Fig. 1: a schematic representation of the bottom bracket gearbox according to a first embodiment, Fig. 2: a schematic representation of the bottom bracket drive according to the invention in a second embodiment, Fig. 3: a switching matrix of the in Fig. 1 and Fig. 2 bottom bracket gearboxes shown, Fig. 4: a schematic representation of the bottom bracket drive according to the invention in a third embodiment, Fig. 5: a schematic representation of the bottom bracket drive according to the invention in a fourth embodiment, Fig. 6: a table with values ​​for the standard translation of the planetary theorems, Fig. 7: a switching matrix of the in Fig. 3 and Fig. 4 shown bottom bracket gearboxes according to the invention.

[0041] Fig. Figure 1 shows a bottom bracket gearbox according to a first embodiment of the invention, which is rotationally symmetrical with respect to a bottom bracket crank shaft 5. Fig. Figure 1 shows only the upper half of the bottom bracket gearbox.

[0042] The bottom bracket gearbox has four shifting elements: a first shifting element S1, a second shifting element S2, a third shifting element S3, and a fourth shifting element S4. The first and fourth shifting elements S1 and S4 are designed as clutches. The second and third shifting elements S2 and S3 are designed as brakes.

[0043] Furthermore, the bottom bracket gearbox comprises a drive shaft 1, a first planetary gear set PS1, which is operatively connected to the drive shaft 1, a second planetary gear set PS2, and an output shaft 2. The drive shaft 1 is non-rotatably connected to a ring gear of the first planetary gear set PS1, and a web of the first planetary gear set PS1 is non-rotatably connected to the output shaft 2. The output shaft 2 is arranged coaxially with the bottom bracket crank axle 5 and non-rotatably connected to a tension member (not shown). The first planetary gear set PS1 is designed as a plus planetary gear set, and the second planetary gear set PS2 is designed as a minus planetary gear set.

[0044] The drive shaft 1 is non-rotatably connected to a sun gear of the second planetary gear set PS2 by means of the first switching element S1. The sun gear of the second planetary gear set PS2 is additionally non-rotatably connected to a gearbox housing 3 by means of a second switching element S2. A web of the second planetary gear set PS2 is non-rotatably connected to a sun gear of the first planetary gear set PS1. A ring gear of the second planetary gear set PS2 is non-rotatably connected to the gearbox housing 3 by means of a third switching element S3 and to the output shaft 2 by means of the fourth switching element S4.

[0045] The first and second planetary gear sets PS1 and PS2 are arranged coaxially with each other. Furthermore, the first and second planetary gear sets PS1 and PS2 are arranged coaxially with the bottom bracket crankshaft 5. In addition, the first and second planetary gear sets PS1 and PS2 are arranged such that the drive shaft 1, for connecting to the ring gear of the first planetary gear set PS1, extends through a plane E. This plane E includes the ring gear, the bridge, and the sun gear of the second planetary gear set PS2. Furthermore, the plane E is perpendicular to the bottom bracket crankshaft 5.

[0046] The bottom bracket gearbox is arranged in a cavity of a bottom bracket housing 9. The in Fig. The bottom bracket gearbox shown forms a main group HG, which, as can be seen from the Fig. 4 and as can be seen in section 5, it is interconnected with other area groups.

[0047] Fig. Figure 2 shows a bottom bracket gearbox according to a second embodiment. The one in Fig. The bottom bracket gearbox shown in section 2 differs from the one in Fig. Figure 1 shows the bottom bracket gearbox in the arrangement of the first and second planetary gear sets PS1 and PS2 relative to each other. In particular, the second planetary gear set PS2 is arranged such that the drive shaft 1 for connecting to the ring gear of the first planetary gear set PS1 does not extend through the plane E.

[0048] Fig. 3 shows the switching matrix for the ones in the Fig. 1 and Fig. The bottom bracket gearbox is shown in Figure 2. The symbol "x" indicates that the respective shifting element is closed. Furthermore, the gear ratio "i" between the input shaft 1 and the output shaft 2, and thus the drive carrier, is specified in the shift matrix for each gear.

[0049] As from Fig. As can be seen in Figure 3, the bottom bracket gearbox has exactly four gears, with the first gear being a direct drive. The remaining gears have a higher gear ratio. In the Fig. 1 and Fig. In the two bottom bracket gearboxes shown, the first planetary gear set PS1 can have a stationary gear ratio of 2.0, and the second planetary gear set PS2 can have a stationary gear ratio of -1.6. For a negative planetary gear set, the stationary gear ratio corresponds to the negative ratio of teeth between the ring gear and the sun gear. For a positive planetary gear set, the stationary gear ratio corresponds to the positive ratio of teeth between the ring gear and the sun gear.

[0050] Fig. Figure 4 shows the bottom bracket gearbox according to a third embodiment. The bottom bracket gearbox differs from the one in Fig. The bottom bracket gearbox shown in Figure 1 is characterized by the fact that the bottom bracket gearbox has a third planetary gear set PS3, which forms a pre-group VG that is technically connected upstream of the main group HG. In particular, the third planetary gear set PS3 is technically connected upstream of the first planetary gear set PS1 and the second planetary gear set PS2, when considering a power flow from the bottom bracket crankshaft 5 to the output shaft 2 during traction operation.

[0051] A ring gear of the third planetary gear set PS3 is non-rotatably connected to a sun gear of the third planetary gear set PS3 by means of a fifth switching element S5. Furthermore, the ring gear of the third planetary gear set PS3 is non-rotatably connected to the gearbox housing 3 by means of a sixth switching element S6. A web of the third planetary gear set PS3 is non-rotatably connected to the bottom bracket crankshaft 5 by means of another drive shaft 6. The sun gear of the third planetary gear set PS3 is non-rotatably connected to the drive shaft 1.

[0052] The fifth switching element S5 is designed as a freewheel and the sixth switching element S6 is designed as a brake. Another difference from the one in Fig. The bottom bracket gearbox shown in 1 consists in the fact that the first shifting element S1 and the fourth shifting element S4 are each designed as a freewheel.

[0053] The in Fig. The bottom bracket gearbox shown in section 5, according to a fourth embodiment, differs from the one shown in Fig. The difference in the bottom bracket gearbox shown in Figure 4 is that the third planetary gear set PS3 does not form a pre-group VG, but a post-group NG. This means that the third planetary gear set PS3 is downstream of the main group HG in terms of drive technology, when considering the power flow from the bottom bracket crankshaft 2 to a further output shaft 7 during pull operation.

[0054] The output shaft 2 is non-rotatably connected to the bridge of the third planetary gear set PS3. The sun gear of the third planetary gear set PS3 is non-rotatably connected to the further output shaft 7, which is non-rotatably connected to the traction element carrier (not shown in the figure). The input shaft 1 is non-rotatably connected to the bottom bracket crankshaft 5.

[0055] Another difference is that the bottom bracket gearbox has an electric machine 8 which is operatively connected to the output shaft 7, as shown by the dashed line. The connection of the electric machine 8 to the output shaft 7 can be made via a superimposed gearbox, a spur gear gearbox, a chain drive and / or a belt drive, with the connection in Fig. 4 is not shown. The connection of the electric machine 8 takes place in a section downstream of the downstream group NG in terms of drive technology.

[0056] The electric machine 8 is not rotationally symmetrical with respect to the bottom bracket crankshaft 5. In particular, the electric machine 8 is arranged radially offset from the bottom bracket crankshaft 5.

[0057] Another difference is that the bottom bracket gearbox has a torque sensor 4, which measures the torque transmitted from the bottom bracket crank axle 5 to the drive shaft 1. The torque sensor 9 can be disc-shaped. Of course, other designs and / or arrangements of the torque sensor 9 are also possible.

[0058] Fig. Figure 6 shows a table with values ​​for the standard translation of the data in the Fig. 4 and Fig. The three planetary sets shown in the table are as follows: As can be seen from the table, the first planetary set PS1 has a standard gear ratio of 2.0, the second planetary set PS2 a standard gear ratio of -1.6, and the third planetary set PS3 a standard gear ratio of -1.5.

[0059] Fig. Figure 7 shows a switching matrix for the [unclear text]. Fig. 4 and Fig. Figure 5 shows a bottom bracket gearbox. The shifting elements that are closed in the respective gear are marked with the symbol "x". If the shifting element is designed as a freewheel, the symbol "x" means that the freewheel is locked. This occurs automatically without external actuation. The shifting elements designed as brakes are closed by at least one actuator.

[0060] The switching matrix also shows that the ones in the Fig. 4 and Fig. The 5 depicted bottom bracket gearboxes each have eight gears. Furthermore, the gear ratio “i” between the bottom bracket crank axle 5 and the cable carrier is specified in the shift matrix for each gear. Reference sign 1 drive shaft 2 Output shaft 3 Gearbox housings 4 Torque sensor 5 Bottom bracket crankshaft 6 additional drive shafts 7 additional output shafts 8 electric machine 9 bottom bracket shell Level E S1 first switching element S2 second switching element S3 third switching element S4 fourth switching element S5 fifth switching element S6 sixth switching element HG main gearbox NG secondary transmission VG pre-transmission PS1 first planetary set PS2 second planetary set PS3 third planetary set

Claims

[1] Bottom bracket gearbox for a bicycle, comprising at least four shifting elements, a drive shaft (1), a first planetary gear set (PS1) operatively connected to the drive shaft (1), a second planetary gear set (PS2) operatively connectable to the drive shaft (1), and an output shaft (2), wherein the drive shaft (1) is non-rotatably connected to a ring gear of the first planetary gear set (PS1) and the output shaft (2) is non-rotatably connected to a web of the first planetary gear set (PS1), characterized by , that the bottom bracket gearbox has an electric machine (8) which is connected downstream of at least one of the planetary sets (PS1, PS2; PS3) in terms of drive technology. [2] Bottom bracket gearbox according to claim 1, characterized by , that a. the first planetary set (PS1) is a plus planetary set and / or that b. the second planetary theorem (PS2) is a negative planetary theorem. [3] Bottom bracket gearbox according to claim 1 or 2, characterized by , that a. a sun gear of the second planetary set (PS2) can be connected to the drive shaft (1) in a rotationally fixed manner by means of a first switching element (S1) and / or can be connected to a gearbox housing (3) in a rotationally fixed manner by means of a second switching element (S2) and / or that b. a bridge of the second planetary set (PS2) is rotationally fixed to a sun gear of the first planetary set (PS1) and / or that c. a ring gear of the second planetary set (PS2) can be connected to the gearbox housing (3) in a rotationally fixed manner by means of a third switching element (S3) and / or can be connected to the output shaft (2) in a rotationally fixed manner by means of a fourth switching element (S4). [4] Bottom bracket gearbox according to one of claims 1 to 3, characterized by , that a. the first planetary gear set (PS1) and the second planetary gear set (PS2) are arranged such that the drive shaft (1) does not extend through a plane (E) that contains the second planetary gear set (PS2), or that b. the first planetary set (PS1) and the second planetary set (PS2) are arranged such that the drive shaft (1) extends through a plane (E) which has the second planetary set (PS2). [5] Bottom bracket gearbox according to any one of claims 1 to 4, characterized by , that the drive shaft (1) can be connected to a bottom bracket crank shaft (5) in a rotationally fixed manner. [6] Bottom bracket gearbox according to any one of claims 1 to 5, characterized by a third planetary set (PS3) that is operatively connected with the first planetary set (PS1) and / or with the second planetary set (PS2). [7] Bottom bracket gearbox according to claim 6, characterized by , that a. an element of the third planetary set (PS3) can be connected to another element of the third planetary set (PS3) by means of a fifth switching element (S5) in a rotationally fixed manner and / or that b. a ring gear of the third planetary set (PS3) can be connected to a gearbox housing (3) in a rotationally fixed manner by means of a sixth switching element (S6). [8] Bottom bracket gearbox according to claim 6 or 7, insofar as the claim is related back to one of claims 1 to 4, characterized by , that a bridge of the third planetary set (PS3) can be connected to the bottom bracket crank shaft (5) in a rotationally fixed manner by means of a further drive shaft (6) and / or a sun gear of the third planetary set (PS3) is connected to the drive shaft (1) in a rotationally fixed manner. [9] Bottom bracket gearbox according to claim 6 or 7, characterized by , that the output shaft (2) is connected to a bridge of the third planetary set (PS3) in a rotationally fixed manner and / or a sun gear of the third planetary set (PS3) is connected to a further output shaft (7) in a rotationally fixed manner. [10] Bottom bracket gearbox according to any one of claims 6 to 9, characterized by the electric machine (8), which a. is downstream of the first planetary set (PS1), the second planetary set (PS2), and the third planetary set (PS3) in terms of drive technology and / or b. is operatively connected or operatively connectable to the output shaft (2) or the further output shaft (7). [11] Bottom bracket with a bottom bracket gearbox according to one of claims 1 to 10, wherein the drive shaft (1) or the further drive shaft (6) is connected to the bottom bracket crank shaft (5) in a rotationally fixed manner. [12] Bottom bracket according to claim 11, comprising a bottom bracket housing (9), wherein the bottom bracket gear is arranged in a cavity of the bottom bracket housing (9). [13] Bicycle with a bottom bracket gearbox according to one of claims 1 to 10 or a bottom bracket according to claim 11 or 12.

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