Gearbox for a bicycle, bottom bracket and bicycle

Abstract

Transmission for a bicycle, with a transmission input shaft (1) which is rotatably connectable to a bottom bracket crankshaft (2), a first planetary gear set (PS1), a second planetary gear set (PS2), a third planetary gear set (PS3), the planetary gear sets being operatively connected to one another, and an electric machine (5), characterized in thatthat one element of the first planetary gear set (PS1) is rotatably connected to a transmission housing (4) by means of a first shifting element (S1), and two elements of the first planetary gear set (PS1) are rotatably connected to one another by means of a second shifting element (S2), and one element of the second planetary gear set (PS2) is rotatably connected to the transmission housing (4) by means of a third shifting element (S3), and two elements of the second planetary gear set (PS2) are rotatably connected to one another by means of a fourth shifting element (S4), and one element of the third planetary gear set (PS3) is operatively connected or operatively connectable to the electric machine (5).

Description

[0001] The invention relates to a transmission for a bicycle, comprising a transmission input shaft which is rotatably connected to a bottom bracket crankshaft, a first planetary gear set, a second planetary gear set, a third planetary gear set, the planetary gear sets being operatively connected to one another, and an electric machine.

[0002] The invention also relates to a bottom bracket with such a gearing. Furthermore, the invention relates to a bicycle with the bottom bracket or the gearing.

[0003] A variety of transmissions are known from the state of the art that can be used in bicycles. For example, US 2011 177 911 A1 describes a transmission that features three planetary gears connected in series with a high-speed ratio. The transmission has a total of seven planetary gear planes, including numerous stepped planets, making the construction of the transmission very complex.

[0004] Bottom bracket gears with an electric auxiliary drive are also known. One such bottom bracket gear is known from DE 10 2013 220 299 A1. This bottom bracket gear also has the disadvantage that the construction of the gear is very complex.

[0005] DE 10 2015 013 280 A1 relates to a bicycle auxiliary drive unit that reduces the load on mechanical elements when they disengage from the ring gear. The unit comprises a planetary gear mechanism with a plurality of ring gears, a transmission unit with a rotation-limiting mechanism for selectively limiting the rotation of a ring gear, and an auxiliary motor that adds additional drive power to the first drive power of the transmission unit.

[0006] JP H10 - 194 186 A relates to a motor-assisted bicycle which integrates an automatic transmission into an electrical auxiliary unit and has an existing torque sensor and a control device.

[0007] JP H08 - 282 575 A relates to a structure for preventing the reverse operation of an electric motor in a bicycle with auxiliary drive, which structure comprises a crankshaft, an electric motor, a differential for combining the manual and electric drive power, a planetary gear for reducing the speed and a one-way clutch for preventing the reverse operation of the electric motor, wherein the main shaft of the electric motor and the sun gear of the planetary gear are on the same axis and the one-way clutch is arranged between the electric motor and the planetary gear.

[0008] WO 2011 / 122 787 A2 relates to a bicycle transmission comprising a crankshaft for transmitting the rotational power from a bicycle pedal to a main shaft, a gear section for changing the gear ratio, a lever control for selecting the gear stages and a clutch for fixing one of the gear wheels.

[0009] JP 2015 - 105 012 A relates to a drive device for an electric bicycle which reduces the load on a bearing between the sun gear and the carrier by aligning the directions of rotation of the sun gear and the carrier, using a planetary mechanism having a sun gear driven by a motor, a ring gear connected to an output shaft, a carrier connected to the crankshaft, and inner and outer planetary gears.

[0010] JP H09 - 123 977 A relates to a transmission device in which the sun gears of two coaxially arranged planetary gears are connected by a combined element to prevent delays in the input of the second planetary gear, and a mechanism is integrated that releases the rotation of a detection element that detects the rotation of the combined element.

[0011] The object of the invention is therefore to provide a transmission which has a low construction cost.

[0012] The object is achieved by the subject matter having the features of the independent patent claims, inter alia by a transmission of the type mentioned at the outset, which is characterized in that an element of the first planetary gear set can be connected in a rotationally fixed manner to a transmission housing by means of a first shifting element, and two elements of the first planetary gear set can be connected in a rotationally fixed manner to one another by means of a second shifting element, and an element of the second planetary gear set can be connected in a rotationally fixed manner to the transmission housing by means of a third shifting element, and two elements of the second planetary gear set can be connected in a rotationally fixed manner to one another by means of a fourth shifting element, and an element of the third planetary gear set is operatively connected or operatively connectable to the electric machine. Advantageous further developments emerge from the subclaims.

[0013] The transmission according to the invention has the advantage of being simple and compact, thus reducing construction costs. In particular, the transmission requires only a few planetary gear planes, which has a beneficial effect on construction costs. Furthermore, the transmission requires little operating effort. A further advantage of the transmission is that it provides, particularly precisely, four gears with a wide gear ratio spread, whereby the provision of the electric motor allows the large gear steps to be compensated for.

[0014] A shaft is not exclusively understood to mean, for example, a cylindrical, rotatably mounted machine element for transmitting torque, but rather also general connecting elements that connect individual components or elements to one another, in particular connecting elements that connect several elements to one another in a rotationally fixed manner.

[0015] The electrical machine consists of at least a rotationally fixed stator and a rotatably mounted rotor and is designed to convert electrical energy into mechanical energy in the form of speed and torque in motor operation, and to convert mechanical energy into electrical energy in the form of current and voltage in generator operation.

[0016] The gear housing can be part of a bottom bracket shell, i.e., it can be constructed in one piece with the bottom bracket shell. Alternatively, the gear housing can be constructed separately from the bottom bracket shell and, when the gear unit is assembled, can be arranged in a cavity of the bottom bracket shell.

[0017] In a special design, the transmission can have exactly three planetary gear sets. The first planetary gear set can provide at least two, in particular exactly two, gears. The second planetary gear set can provide at least two, in particular exactly two, gears.

[0018] A first gear in the first planetary gear set can be a direct gear, meaning it has a ratio of 1. The second gear of the first planetary gear set can be a high-gear ratio, meaning the ratio is less than 1. The first gear in the second planetary gear set can also be a direct gear, and the second gear can also have a high-gear ratio.

[0019] As a result, a group transmission can be realized in which the first planetary gear set and the second planetary gear set are each designed as a two-speed partial transmission, so that four gears can be provided by the transmission according to the invention. The second planetary gear set provides a single gear step, for example, of 1.62. The first planetary gear set provides a double gear step and serves as a range group.

[0020] The element of the first planetary gear set can be a ring gear of the first planetary gear set. The ring gear of the first planetary gear set can be connected in a rotationally fixed manner to a sun gear of the first planetary gear set by means of the second shifting element. This is advantageous because the lowest support torques occur in this design. Alternatively, the sun gear and the carrier of the first planetary gear set, or the ring gear and the carrier of the first planetary gear set, can each be connected in a rotationally fixed manner to one another by means of the second shifting element.

[0021] The element of the second planetary gear set can be a sun gear of the second planetary gear set. The sun gear of the second planetary gear set can be connected in a rotationally fixed manner to a ring gear of the second planetary gear set by means of the fourth shifting element. This is advantageous because the lowest support torques occur in this design. Alternatively, the sun gear and the carrier, or the ring gear and the carrier of the second planetary gear set, can each be connected in a rotationally fixed manner to one another.

[0022] The element of the third planetary gear set can be a sun gear of the third planetary gear set. The third planetary gear set functions as a superposition gear. In particular, the third planetary gear set can be supplied with the torque provided by the electric motor and the torque introduced into the transmission via the bottom bracket crankshaft, which is not part of the transmission.

[0023] The first and third switching elements can be designed as a brake. The second and fourth switching elements can be designed as a freewheel. Alternatively, it is possible for the second and / or fourth switching elements to be designed as a clutch, in particular a switchable clutch.

[0024] If the second and fourth switching elements are designed as a clutch, the second switching element and the first switching element can be combined to form a double switching element. This is possible because the first and second switching elements are never closed at the same time. Furthermore, the third and fourth switching elements can be combined to form a double switching element. This is possible because the third and fourth switching elements are never closed at the same time. With a double switching element, the two switching elements are actuated by a single actuator. Of course, it is alternatively conceivable that if the second and / or fourth switching element are designed as a clutch, each switching element is designed as an individual switching element and thus four actuators are provided.

[0025] In particular, the first and third shifting elements can be designed as positive-locking or friction-locking brakes. In particular, the first shifting element designed as a brake can be designed as a one-way brake, i.e., a switchable freewheel brake, to prevent the bottom bracket crankshaft from locking when pedaling backward while the brake is applied.

[0026] It is particularly advantageous if the second planetary gear set and the third planetary gear set are arranged and designed in such a way that they have the same ring gear. In this case, the construction effort is reduced.

[0027] Furthermore, it is advantageous to select an identical stationary gear ratio for the first planetary gear set, the second planetary gear set, and / or the third planetary gear set. This offers the advantage of allowing the use of many identical parts, which is advantageous from a cost perspective.

[0028] In a particular embodiment, the first shifting element and / or the second shifting element and / or the third shifting element and / or the fourth shifting element can be arranged radially above the first planetary gear set and / or the second planetary gear set and / or the third planetary gear set. In particular, a diameter of the first shifting element and / or the second shifting element and / or the third shifting element and / or the fourth shifting element can be larger than an outer diameter of the first planetary gear set and / or the second planetary gear set and / or the third planetary gear set. In particular, the second shifting element and / or the fourth shifting element can be nested above the planetary gear sets. Such an arrangement of the shifting elements offers the advantage that installation space can be saved in the axial direction. This is particularly advantageous because the installation space in a bottom bracket is limited.A further advantage of such an arrangement of the switching elements is that the switching elements are easily accessible from the outside.

[0029] When viewed in the direction of power flow from the transmission input shaft to a transmission output shaft, the planetary gear sets can be arranged in the following order: first planetary set, second planetary set, third planetary set or first planetary set, third planetary set, second planetary set or second planetary set, first planetary set, third planetary set or third planetary set, first planetary set, second planetary set or second planetary set, third planetary set, first planetary set or third planetary set, second planetary set, first planetary set.

[0030] The direction of power flow from the transmission input shaft to the transmission output shaft is particularly important during traction operation. All of the planetary gear set configurations mentioned above have the same gear ratio series, meaning the overall function of the transmission is the same for all configurations. The shift matrix is ​​also the same for all configurations. Differences exist in the speed and torque ratios occurring at the individual planetary gear sets.

[0031] The transmission input shaft can be non-rotatably connected to another element of the planetary gear set arranged first in the direction of power flow. If the first or second planetary gear set is arranged first, this can be the carrier of the first or second planetary gear set. If the third planetary gear set is arranged first, the transmission input shaft can be non-rotatably connected to the ring gear of the third planetary gear set.

[0032] The transmission output shaft can be non-rotatably connected to another element of the planetary gear set arranged last in the direction of power flow. This can be the sun gear of the first planetary gear set if the first planetary gear set is arranged last, the ring gear of the second planetary gear set if the second planetary gear set is arranged last, or the carrier of the third planetary gear set if the third planetary gear set is arranged last.

[0033] In a special embodiment, a sun gear of the first planetary gear set can be non-rotatably connected to a carrier of the second planetary gear set, and a carrier of the first planetary gear set can be non-rotatably connected to the transmission input shaft. A ring gear of the second planetary gear set can be non-rotatably connected to a ring gear of the third planetary gear set. A carrier of the third planetary gear set can be non-rotatably connected to the transmission output shaft.

[0034] In an alternative design, a carrier of the second planetary gear set can be non-rotatably connected to the transmission input shaft, and a ring gear of the second planetary gear set can be non-rotatably connected to a carrier of the first planetary gear set. The sun gear of the first planetary gear set can be non-rotatably connected to a ring gear of the third planetary gear set. The carrier of the third planetary gear set can be non-rotatably connected to the transmission output shaft. In this design, the third shifting element can be designed as a one-way brake to prevent locking when reversing. In this case, the fourth shifting element can be a freewheel.

[0035] The two aforementioned designs have the advantage that the third planetary gear set is positioned last in the direction of power flow. This offers the advantage that the summation of the torque delivered via the bottom bracket crankshaft and the torque delivered by the electric motor only occurs at the output of the transmission, and the first and second planetary gear sets are only loaded with the lower muscle power torque and thus not with the torque delivered by the electric motor.

[0036] In a particular embodiment, the electric motor can be arranged offset, particularly in the radial direction, from a central axis of the transmission. In particular, the electric motor can be arranged parallel to a central axis of the transmission and / or a central axis of the bottom bracket crankshaft. The first and / or second and / or third planetary gear sets can be arranged coaxially with one another. A central axis of the planetary gear sets can correspond to a central axis of the transmission.

[0037] The electric motor can be operatively connected to the third element of the third planetary gear set via a spur gear and / or a belt drive and / or a superposition gear. The provision of the spur gear stage and / or the belt drive offers the advantage that the electric motor needs to provide less torque and can therefore rotate faster.

[0038] When controlling or regulating the electric motor, virtual intermediate gears or continuously variable operation can be simulated by varying the speed of the electric motor, allowing the driver to smoothly transition between the transmission gear ratios. No torque sensor is required to control and / or regulate the electric motor, as the electric motor can determine the required support torque on the third planetary gear set and thus indirectly determine the muscle drive torque.

[0039] At a given driving speed, i.e. a given speed at the transmission output shaft, the electric motor delivers the highest power output in first gear, as the electric motor then has the highest speed. This corresponds to the highest level of assistance from the electric motor. In contrast, fourth gear delivers the lowest power output from the electric motor, as the electric motor then has the lowest speed. This also corresponds to the lowest level of assistance. Automatic gearshift and automatic gear selection are therefore advantageous, as drivers are usually less familiar with these relationships. Since the transmission has four gears, there are also four levels of assistance for the electric motor.

[0040] When the transmission is operating in reverse, particularly when the bicycle is pushed backward, the electric motor can compensate for the speed, so that even if the first or second planetary gear set is locked, meaning the first or third shifting element is engaged, shifting backward is still possible. This offers the advantage that a one-way brake is not required for the third shifting element, or rather, a single brake that, when applied, acts in both directions is sufficient.

[0041] Alternatively or additionally, the electric motor can be operatively connected to the element of the third planetary gear set by means of a fifth shifting element, which is, for example, a freewheel. The provision of the fifth shifting element offers the advantage that it can prevent the element of the third planetary gear set from rotating backward. Another advantage of the fifth shifting element is that it allows purely mechanical operation of the transmission without the electric motor.

[0042] A bottom bracket with the bottom bracket crankshaft and the transmission according to the invention is particularly advantageous. The transmission input shaft is connected to the bottom bracket crankshaft in a rotationally fixed manner. A design in which the transmission is arranged within a cavity of the bottom bracket shell is particularly advantageous. In this case, a particularly compact bottom bracket can be provided that is easy to assemble. A bicycle with the transmission or the bottom bracket is particularly advantageous.

[0043] The subject matter of the invention is schematically illustrated in the figures and is described below with reference to the figures, wherein identical or equivalent elements are generally provided with the same reference numerals. In the figures: Fig. 1 a schematic representation of the transmission according to the invention according to a first embodiment, Fig. 2 a schematic representation of the transmission according to a second embodiment, Fig. 3 a table with values ​​of stationary ratios of the three planetary gear sets of the transmission according to the invention, Fig. 4 a switching matrix of the Fig. 1 and Fig. 2 shown transmission according to the invention.

[0044] The Fig. The transmission shown in Figure 1 has a transmission input shaft 1, which is connected in a rotationally fixed manner to a bottom bracket crankshaft 2. Furthermore, the transmission has a first planetary gear set PS1, a second planetary gear set PS2, and a third planetary gear set PS3, which are operatively connected to one another. Furthermore, the transmission has a first shifting element S1, a second shifting element S2, a third shifting element S3, a fourth shifting element S4, and a transmission output shaft 3. Fig. 1 only half of the previously mentioned transmission components are shown.

[0045] The planetary gear sets PS1, PS2, PS3 are arranged coaxially to one another and / or are rotatable about a central axis M of the transmission. The transmission output shaft 3 is also coaxial to the central axis M. The ring gear of the first planetary gear set PS1 is rotatably connected to a transmission housing 4 by means of the first shifting element S1. Furthermore, the ring gear of the first planetary gear set PS1 is rotatably connected to a sun gear of the first planetary gear set PS1 by means of the second shifting element S2. The sun gear is also rotatably connected to a carrier of the second planetary gear set PS2. A carrier of the first planetary gear set PS1 is rotatably connected to the transmission input shaft 1.

[0046] A sun gear of the second planetary gear set PS2 is rotationally fixed to the transmission housing 4 by means of a third shifting element S3. Furthermore, the sun gear of the second planetary gear set PS2 is rotationally fixed to a ring gear of the second planetary gear set PS2 by means of a fourth shifting element S4. The ring gear of the second planetary gear set PS2 is also rotationally fixed to a ring gear of the third planetary gear set PS3. A carrier of the third planetary gear set PS3 is rotationally fixed to the transmission output shaft 3. The sun gear of the third planetary gear set PS3 is operatively connected to an electric motor 5 of the transmission. As a result, the third planetary gear set PS3 acts as a superposition gear.

[0047] The active connection of the electric machine 5 with the sun gear of the third planetary gear set PS3 can be achieved by a Fig. 1. The electric motor 5 is arranged axially parallel to the bottom bracket crankshaft 2. Furthermore, the electric motor 5 is arranged offset in the radial direction from the bottom bracket crankshaft 2. The transmission is arranged within a cavity 7 of a bottom bracket shell 6. The transmission housing 4 can be integrally connected to the bottom bracket shell. The bottom bracket crankshaft 2 has a pedal 8 at each end.

[0048] In the Fig. In the embodiment shown in Figure 1, the planetary gear sets are arranged in the following order in the direction of power flow from the transmission input shaft 1 to the transmission output shaft 3: first planetary gear set PS1, second planetary gear set PS2, and third planetary gear set PS3. The transmission output shaft 3 is rotationally fixedly connected to a traction mechanism carrier 9. The traction mechanism carrier 9 can be a sprocket or a belt pulley and is operatively connected to a rear wheel by means of a chain or belt (not shown).

[0049] The Fig. The transmission according to the second embodiment shown in Figure 2 differs from that shown in Fig. 1 according to the first embodiment, the planetary gear sets are arranged in the direction of power flow during traction operation between the transmission input shaft 1 and the transmission output shaft 3 in the order: second planetary gear set PS2, first planetary gear set PS1, and third planetary gear set PS3.

[0050] The carrier of the second planetary gear set PS2 is rotationally fixedly connected to the transmission input shaft 1. The ring gear of the second planetary gear set PS2 is rotationally fixedly connected to the carrier of the first planetary gear set PS1 and is rotationally fixedly connected to the sun gear of the second planetary gear set PS2 by means of the fourth shifting element S4. The sun gear of the first planetary gear set PS1 is rotationally fixedly connected to the ring gear of the third planetary gear set. Otherwise, the transmission according to the second embodiment is designed like the transmission according to the first embodiment.

[0051] Fig. Figure 3 shows a table with values ​​for the stationary gear ratios of the planetary gear sets. The stationary gear ratio corresponds to the negative ratio of the number of teeth between the ring gear and the sun gear. Fig. As can be seen in Figure 3, the three planetary gear sets have the same stationary gear ratio.

[0052] Fig. 4 shows the switching matrix for the Fig. 1 and Fig. 2 shown gearbox. In addition, Fig. 4 shows the values ​​of the gear ratios "i" between the transmission input shaft 1 and the transmission output shaft 3. The gear ratios are valid under the assumption that the sun gear of the third planetary gear set PS3 is locked. The table also shows the values ​​for the gear steps "phi." The torque ratio is independent of the prevailing speeds. Due to the speed superposition with the electric motor, the speed ratio is variable.

[0053] The transmission has four gears, with a first gear being achieved by closing the second and fourth shift elements S2, S4, with the remaining shift elements open. Shifting from first to second gear is achieved by opening the fourth and closing the third shift element S4, S3, with the remaining shift elements open. A third gear can be achieved by closing the first and fourth shift elements S1, S4, with the remaining shift elements open. A fourth gear can be achieved by closing the first and third shift elements S1, S3, with the remaining shift elements open. Reference symbol 1 transmission input shaft 2 bottom bracket crankshaft 3 Gearbox output shaft 4 Gearbox housing 5 electric machine 6 bottom bracket shell 7 Cavity 8 Pedal 9 traction mechanism carrier M Center axis of the gearbox S1 first switching element S2 second switching element S3 third switching element S4 fourth switching element PS1 first planetary gear set PS2 second planetary gear set PS3 third planetary set

Claims

[1] Transmission for a bicycle, with a transmission input shaft (1) which is rotatably connected to a bottom bracket crankshaft (2), a first planetary gear set (PS1), a second planetary gear set (PS2), a third planetary gear set (PS3), the planetary gear sets being operatively connected to one another, and an electric machine (5), characterized bythat one element of the first planetary gear set (PS1) can be connected in a rotationally fixed manner to a transmission housing (4) by means of a first switching element (S1), and two elements of the first planetary gear set (PS1) can be connected in a rotationally fixed manner to one another by means of a second switching element (S2), and one element of the second planetary gear set (PS2) can be connected in a rotationally fixed manner to the transmission housing (4) by means of a third switching element (S3), and two elements of the second planetary gear set (PS2) can be connected in a rotationally fixed manner to one another by means of a fourth switching element (S4), and one element of the third planetary gear set (PS3) is operatively connected or operatively connectable to the electric machine (5). [2] Transmission according to claim 1, characterized by , that a. the element of the first planetary gear set (PS1) is a ring gear of the first planetary gear set (PS1) or that b. the element of the first planetary gear set (PS1) is a ring gear of the first planetary gear set (PS1) and the ring gear can be connected in a rotationally fixed manner to a sun gear of the first planetary gear set (PS1) by means of the second switching element (S2). [3] Transmission according to claim 1 or 2, characterized by , that a. the element of the second planetary gear set (PS2) is a sun gear of the second planetary gear set (PS2) or that b. the element of the second planetary gear set (PS2) is a sun gear of the second planetary gear set (PS2) and the sun gear can be connected in a rotationally fixed manner to a ring gear of the second planetary gear set (PS2) by means of the fourth switching element (S4). [4] Transmission according to one of claims 1 to 3, characterized by that the element of the third planetary set (PS3) is a sun gear of the third planetary set (PS3). [5] Transmission according to one of claims 1 to 4, characterized bythat the second planetary gear set (PS2) and the third planetary gear set (PS3) have the same ring gear. [6] Transmission according to one of claims 1 to 5, characterized by that the first switching element (S1) and / or the second switching element (S2) and / or the third switching element (S3) and / or the fourth switching element (S4) is arranged in the radial direction above the first planetary gear set (PS1) and / or the second planetary gear set (PS2) and / or the third planetary gear set (PS3). [7] Transmission according to one of claims 1 to 6, characterized by that the planetary gear sets, when viewed in a power flow direction from the transmission input shaft (1) to a transmission output shaft (3), are arranged in the following order: a. first planetary gear set (PS1), second planetary gear set (PS2), third planetary gear set (PS3) or b. first planetary gear set (PS1), third planetary gear set (PS3), second planetary gear set (PS2) or c. second planetary gear set (PS2), first planetary gear set (PS1), third planetary gear set (PS3) or d. third planetary gear set (PS3), first planetary gear set (PS1), second planetary gear set (PS2) or e. second planetary gear set (PS2), third planetary gear set (PS3), first planetary gear set (PS1) or f. third planetary set (PS3), second planetary set (PS2), first planetary set (PS1) are arranged. [8] Transmission according to one of claims 1 to 7, characterized by , that a. the transmission input shaft (1) is connected in a rotationally fixed manner to another element of the planetary gear set arranged first in the direction of power flow and / or that b. the transmission output shaft (3) is connected in a rotationally fixed manner to another element of the planetary gear set arranged last in the direction of power flow. [9] Transmission according to one of claims 1 to 8, characterized by , that a sun gear of the first planetary gear set (PS1) is connected in a rotationally fixed manner to a carrier of the second planetary gear set (PS2) and a carrier of the first planetary gear set (PS1) is connected in a rotationally fixed manner to the transmission input shaft (1) and a ring gear of the second planetary gear set (PS2) is connected in a rotationally fixed manner to a ring gear of the third planetary gear set (PS3) and a web of the third planetary gear set (PS3) is non-rotatably connected to the transmission output shaft (3). [10] Transmission according to one of claims 1 to 8, characterized by , that a carrier of the second planetary gear set (PS2) is connected in a rotationally fixed manner to the transmission input shaft (1) and a ring gear of the second planetary gear set (PS2) is connected in a rotationally fixed manner to a carrier of the first planetary gear set (PS1) and a sun gear of the first planetary gear set (PS1) is connected in a rotationally fixed manner to a ring gear of the third planetary gear set (PS3) and a web of the third planetary gear set (PS3) is non-rotatably connected to the transmission output shaft (3). [11] Transmission according to one of claims 1 to 10, characterized by that the electric machine (5) is arranged offset to a central axis (M) of the transmission, in particular to a central axis of the first and / or second and / or third planetary gear set. [12] Transmission according to one of claims 1 to 11, characterized by , that a. the electric machine (5) can be operatively connected to the element of the third planetary gear set (PS3) by means of a fifth switching element and / or that b. the electric machine (5) is operatively connected to the third element of the third planetary gear set by means of a superposition gear and / or a spur gear and / or a belt drive. [13] Bottom bracket with a bottom bracket crankshaft (2) and a transmission according to one of claims 1 to 12, characterized bythat the transmission input shaft (1) is connected to the bottom bracket crankshaft (2) in a rotationally fixed manner. [14] Bottom bracket according to claim 13, characterized by a bottom bracket shell (6), wherein the gear is arranged within a cavity (7) of the bottom bracket shell (6). [15] Bicycle with a transmission according to any one of claims 1 to 12 or a bottom bracket according to claim 13 or 14.

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