Bottom bracket gear and bottom bracket for a bicycle and bicycle

Abstract

Bottom bracket gear for a bicycle, with a planetary gear set (PS1), an electric machine (1) and a manual transmission (2) which has a manual transmission input shaft (3) and a manual transmission output shaft (4), wherein a sun gear of the planetary gear set (PS1) is operatively connected or operatively connectable to the electric machine (1), a web of the planetary gear set (PS1) is rotatably connectable to a bottom bracket crankshaft (7) and a ring gear of the planetary gear set (PS1) is rotatably connected to the manual transmission input shaft (3), characterized in that the manual transmission output shaft (4) is rotatably connected to a traction mechanism carrier (8) of the bottom bracket gear set.

Description

[0001] The invention relates to a bottom bracket gear for a bicycle, with a planetary gear set, an electric machine, and a manual transmission having a manual transmission input shaft.

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

[0003] A variety of transmissions are known from the state of the art for use 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 assembly of the transmission very complex.

[0004] DE 10 2009 045 447 A1 relates to a bicycle with electric auxiliary drive, comprising an electric motor, a battery, a crank mechanism with pedal cranks attached to a pedal crankshaft, and a planetary gear for driving the bicycle both by the electric motor and by the muscle power of a rider, wherein the planetary gear and the electric motor are arranged around the pedal crankshaft of the crank mechanism.

[0005] DE 11 2015 005 678 T5 relates to a drive unit for a bicycle. This drive unit comprises a planetary gear mechanism, a first motor, and a second motor. The planetary gear mechanism is equipped with a sun gear, a ring gear, a plurality of planetary gears, and a carrier, and the motors transmit torque to the carrier and the sun gear.

[0006] DE 848 016 B concerns a drive unit for a bicycle.

[0007] JP H10-194 186 A relates to an automatic transmission and an electric auxiliary unit controlled by a torque sensor and a control unit to provide a compact arrangement and facilitate the gear shifting operation.

[0008] DE 10 2015 013 280 A1 relates to a bicycle drive unit and comprises a planetary gear mechanism, a transmission unit with rotation limiting mechanism and an auxiliary motor.

[0009] WO 2011 / 122 787 A2 relates to a bicycle gearshift comprising a crank arm, a gearing portion for changing the gear ratio, a lever control portion for selecting the gear stage, and a clutch means for fixing a ring gear for controlling the gearshift operation.

[0010] The object of the invention is therefore to provide a bottom bracket gear that can be assembled more easily.

[0011] The problem is solved by a bottom bracket transmission of the type mentioned above, which is characterized in that a sun gear of the planetary gear set is operatively connected or operatively connectable to the electric motor, a carrier of the planetary gear set is rotationally fixedly connected to a bottom bracket crankshaft, and a ring gear of the planetary gear set is rotationally fixedly connected to the manual transmission input shaft. Furthermore, the problem is solved by the subject matter of the further independent patent claims. Advantageous developments are evident from the subclaims.

[0012] The bottom bracket gear according to the invention has the advantage of being compact. This allows the bottom bracket gear to require significantly fewer planetary gear planes than the prior art gear, thus reducing construction costs. A further advantage of the bottom bracket gear according to the invention is that the planetary gear set is located upstream of the manual transmission. The planetary gear set serves as a superposition gear in which the torque provided by the electric motor and the torque provided by the bottom bracket crankshaft are superimposed. This superposition function offers the advantage of compensating for large gear changes.

[0013] The provision of the planetary gear set offers the advantage that the gearbox is subjected to a lower torque than that applied to the bottom bracket crankshaft, which is not part of the bottom bracket transmission. Specifically, the torque exerted by the user on the bottom bracket crankshaft is split at the planetary gear set, with one portion being directed to the electric motor and another serving as the output torque. This means that the torque exerted on the bottom bracket crankshaft is reduced right from the start by the planetary gear set, so that the gearbox is subjected to a lower torque. This is beneficial for the service life of the gearbox components.

[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] In the sense of the invention, the manual transmission is a transmission by means of which a predefined number of gears, i.e. fixed gear ratios between the manual transmission input shaft and a manual transmission output shaft, can be switched by switching elements.

[0017] In a special design, the manual transmission can have a first planetary gear set and a second planetary gear set, with the first planetary gear set being operatively connected to the manual transmission input shaft and the second planetary gear set being operatively connected to a manual transmission output shaft. A bottom bracket transmission designed in this way has the advantage of low construction costs, as there are a maximum of three planetary gear planes. Furthermore, the bottom bracket transmission has the advantage of being compact and requiring minimal operating effort.

[0018] The first planetary gear set can be arranged and configured such that at least two, in particular exactly two, gears can be realized with the first planetary gear set. The second planetary gear set can be arranged and configured such that at least two, in particular exactly two, gears can be realized with the second planetary gear set. This means that exactly four gears can be realized with the bottom bracket gear set.

[0019] In the first planetary gear set, the first gear is a direct gear, i.e., a gear with a ratio of 1, and the second gear is a high gear. In the second planetary gear set, the first gear is a low gear, and the second gear is a direct gear. The advantage of the bottom bracket transmission according to the invention is that the torque increase only occurs at the end of the transmission, meaning no other gear sets are subjected to the high torque.

[0020] The manual transmission and / or the planetary gear set can be arranged coaxially to the bottom bracket crankshaft. In addition, the manual transmission can have a first switching element by means of which two components of the first planetary gear set can be connected to one another in a rotationally fixed manner. This allows the first planetary gear set to be blocked. There are three blocking variants that achieve the desired locking effect. For example, the first switching element can be arranged between the sun gear and the ring gear of the first planetary gear set, or between the sun gear and the carrier of the first planetary gear set, or between the ring gear and the carrier of the first planetary gear set. The lowest support torques occur when the switching element can connect the sun gear and the ring gear in a rotationally fixed manner. The manual transmission can also have a second switching element by means of which a component of the first planetary gear set can be connected to a bottom bracket transmission housing in a rotationally fixed manner.

[0021] The bottom bracket gear housing can be part of the bottom bracket shell, i.e., it can be constructed in one piece with the bottom bracket shell. Alternatively, the bottom bracket gear housing can be constructed separately from the bottom bracket shell and, when the bottom bracket gear is assembled, can be arranged in a cavity of the bottom bracket shell.

[0022] In addition, the manual transmission can have a third shifting element by means of which two components of the second planetary gear set can be connected to one another in a rotationally fixed manner. There are three blocking variants that achieve the desired locking effect. For example, the first shifting element can be arranged between the sun gear and the ring gear of the first planetary gear set, or between the sun gear and the carrier of the first planetary gear set, or between the ring gear and the carrier of the first planetary gear set. The lowest support torques occur when the shifting element can connect the sun gear and the ring gear in a rotationally fixed manner. In addition, the manual transmission can have a fourth shifting element by means of which a component of the second planetary gear set can be connected to the bottom bracket transmission housing in a rotationally fixed manner.

[0023] The first and third shifting elements can be designed as clutches. The second and fourth shifting elements can be designed as brakes. The individual shifting elements can be designed as single shifting elements. Alternatively, the first and second shifting elements can be designed as a double shifting element. Furthermore, the third and fourth shifting elements can be designed as a double shifting element. The design as a double shifting element is possible because the first and second shifting elements or the third and fourth shifting elements are never closed together. The first and second shifting elements can in particular be designed as a freewheel because the direction of the torque applied to the bottom bracket crankshaft is always the same.

[0024] According to one embodiment of the bottom bracket transmission, the sun gear of the first planetary gear set can be rotationally fixedly connected to the bottom bracket transmission housing by means of the second shifting element, a carrier of the first planetary gear set can be rotationally fixedly connected to the manual transmission input shaft, and a ring gear of the first planetary gear set can be rotationally fixedly connected to a shaft. Furthermore, a sun gear of the second planetary gear set can be rotationally fixedly connected to the shaft, a carrier of the second planetary gear set can be rotationally fixedly connected to the manual transmission output shaft, and a ring gear of the second planetary gear set can be rotationally fixedly connected to the bottom bracket transmission housing by means of the fourth shifting element. The sun gear of the first planetary gear set can be rotationally fixedly connected to the shaft by means of the first shifting element. The ring gear of the second planetary gear set can be rotationally fixedly connected to the shaft by means of the third shifting element.The first planetary gear set can provide a single gear step, while the second planetary gear set can provide a double gear step. Furthermore, the second planetary gear set can serve as a range-change group.

[0025] In this version, the first planetary gear set has a ratio of 1 as first gear and a ratio of 0.38 as second gear. The second planetary gear set has a ratio of 1.62 as first gear and a ratio of 1 as second gear.

[0026] In an alternative embodiment of the bottom bracket gear, a sun gear of the first planetary gear set can be rotationally fixed to a shaft, a carrier of the first planetary gear set can be rotationally fixed to the manual transmission input shaft, and a ring gear of the first planetary gear set can be rotationally fixed to the transmission housing by means of the second shifting element. The sun gear of the second planetary gear set can be rotationally fixed to the transmission housing by means of the fourth shifting element, a carrier of the second planetary gear set can be rotationally fixed to the manual transmission output shaft, and a ring gear of the second planetary gear set can be rotationally fixed to the shaft. In addition, the ring gear of the first planetary gear set can be rotationally fixed to the shaft by means of the first shifting element, and / or the sun gear of the second planetary gear set can be rotationally fixed to the shaft by means of the third shifting element.

[0027] In the alternative design, the first planetary gear set makes a double gear jump to the fast gear ratio and the second planetary gear set makes a single gear jump to the slow gear ratio. This shifts the overall gear ratio one gear step higher than the previous design. To achieve the same handling as the previous design, a smaller transmission carrier or a larger gear on the rear wheel can be used. In the alternative design, the first planetary gear set can have a ratio of 1 as the first gear and a ratio of 0.38 as the second gear. The second planetary gear set can have a ratio of 1.62 as the first gear and a ratio of 1 as the second gear.

[0028] The result is a bottom bracket gear with a compact design and low operating effort, featuring four gears with a wide gear ratio spread. Furthermore, a bottom bracket gear with exactly one planetary gear set and a manual gear with exactly two planetary gear sets can be provided. This allows a bottom bracket gear with exactly three planetary gear sets to be provided. Alternatively or additionally, a bottom bracket gear with exactly four shifting elements can be provided. The bottom bracket gear can be implemented as a group gear.

[0029] According to the invention, the manual transmission output shaft is non-rotatably connected to the traction mechanism carrier. The traction mechanism carrier can be a sprocket or a belt pulley. The chain operatively connected to the sprocket or the belt operatively connected to the belt pulley can serve to transmit the torque applied to the manual transmission output shaft to, for example, a rear wheel of the bicycle.

[0030] The electric machine can be arranged offset from a central axis of the bottom bracket gearing. In particular, the electric machine can be arranged parallel to a central axis of the bottom bracket gearing and / or a central axis of the bottom bracket crankshaft. The electric machine can be operatively connected to the planetary gear set by means of a spur gear stage and / or a belt drive. Alternatively or additionally, a pre-reduction gear, such as a further planetary gear set, can be present, which is arranged, for example, directly on the electric machine. The provision of the pre-reduction gear and / or the spur gear stage and / or the belt drive offers the advantage that the electric machine has to provide less torque and can therefore rotate faster.

[0031] Alternatively or additionally, a freewheel may be present between the electric machine and the sun gear of the planetary gear set, so that the electric machine can be operatively connected to the planetary gear set.

[0032] In order for the electric motor to provide motor support, it must rotate in reverse, meaning opposite to the direction of rotation of the pedal crankshaft, so that the ring gear accelerates. No torque sensor is required for control or regulation, since the electric motor can determine the required support torque on the planetary gear set and thus indirectly the torque applied to the bottom bracket crankshaft.

[0033] 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. This allows the rider to enjoy smooth transitions between the large gear steps of the bottom bracket gear. For a given driving speed, i.e. a given speed at the manual transmission output shaft, the electric motor delivers the highest power output in first gear, as this is when the electric motor 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 this is when the electric motor has the lowest speed. This also corresponds to the lowest level of assistance. Automatic gear shifting and automatic gear selection are therefore advantageous, as these relationships are usually less familiar to the rider.Since the bottom bracket gear has four gears, there are also four levels of support from the electric motor.

[0034] The planetary gear set, the first planetary gear set, and the second planetary gear set can be designed and arranged such that each planetary gear set has the same stationary gear ratio. This offers the advantage that many identical parts can be used, which is advantageous from a cost perspective. In a power flow between the bottom bracket crankshaft and the traction mechanism carrier during traction operation, i.e., starting from the pedal crankshaft and moving towards the traction mechanism carrier, the planetary gear sets can be arranged in the following order: planetary gear set, first planetary gear set, and second planetary gear set. Alternatively, the planetary gear sets can be arranged in the following order: planetary gear set, second planetary gear set, and first planetary gear set during traction operation.

[0035] A bottom bracket with the bottom bracket crankshaft and the bottom bracket gearing according to the invention is particularly advantageous, with the web of the first planetary gear set being non-rotatably connected to the bottom bracket crankshaft. A design in which the bottom bracket gearing 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 bottom bracket gearing or the bottom bracket is particularly advantageous.

[0036] 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. Herein: Fig. 1 a schematic representation of the bottom bracket gear according to the invention according to a first embodiment, Fig. 2 a schematic representation of the bottom bracket gear according to a second embodiment, in which the gearbox is shown in detail, Fig. 3 Values ​​of the stationary gear ratio of the planetary gear sets used in the bottom bracket gearbox according to the second embodiment, Fig. 4 the switching matrix of the bottom bracket gear according to the second embodiment, Fig. 5 a schematic representation of a bottom bracket gear according to the invention according to a third embodiment, Fig. 6 Values ​​of the stationary gear ratio of the planetary gear sets used in the bottom bracket gearbox according to the third embodiment, Fig. 7 the switching matrix of the bottom bracket gear according to the third embodiment.

[0037] The Fig. The bottom bracket gear shown in Figure 1 comprises an electric motor 1, a planetary gear set PS1, and a manual transmission 2, which has a manual transmission input shaft 3 operatively connected to the planetary gear set PS1. A sun gear of the planetary gear set PS1 is operatively connected to the electric motor 1. A carrier of the planetary gear set PS1 is rotationally fixedly connected to a bottom bracket crankshaft 7, and a ring gear of the planetary gear set is rotationally fixedly connected to the manual transmission input shaft 3.

[0038] The manual transmission 2 also has a manual transmission output shaft 4, which is operatively connected to a traction mechanism carrier 8. The traction mechanism carrier 8 is designed as a chain wheel or belt pulley. The bottom bracket crankshaft 7 has a pedal 9 at each of its two ends.

[0039] In Fig. 2 shows the bottom bracket gear according to a second embodiment. The bottom bracket gear differs from the one shown in Fig. 1 is distinguished by the fact that the gearbox 2 is shown in detail. The illustrated bottom bracket gearbox is rotationally symmetrical to a center axis of the bottom bracket crankshaft 7, with only the upper half of the bottom bracket gearbox being shown. The gearbox 2 has a first planetary gear set PS2 and a second planetary gear set PS3. Furthermore, the gearbox 2 has a first shifting element S1, a second shifting element S2, a third shifting element S3, and a fourth shifting element S4.

[0040] A sun gear of the first planetary gear set PS2 is rotationally fixedly connected to a transmission housing 5 by means of the second shifting element S2. A carrier of the first planetary gear set PS2 is rotationally fixedly connected to the manual transmission input shaft 3. A ring gear of the first planetary gear set PS2 is rotationally fixedly connected to a shaft 6.

[0041] In contrast, a sun gear of the second planetary gear set PS3 is non-rotatably connected to the shaft 6. A carrier of the second planetary gear set PS3 is non-rotatably connected to the manual transmission output shaft 4. A ring gear of the second planetary gear set is non-rotatably connected to the transmission housing 5 by means of the fourth shift element S4.

[0042] The sun gear of the first planetary gear set PS2 is rotationally fixed to shaft 6 and thus to the ring gear of the first planetary gear set PS2 by means of the first shifting element S1. The ring gear of the second planetary gear set PS3 is rotationally fixed to shaft 6 and thus to the sun gear of the second planetary gear set PS3 by means of the third shifting element S3. As a result, the first planetary gear set PS2 can be locked by means of the first shifting element S1, and the second planetary gear set PS3 can be locked by means of the third shifting element S3.

[0043] The electric machine 1 is arranged offset axially parallel to the bottom bracket crankshaft 7, in particular offset in the radial direction to a central axis M of the bottom bracket gear and / or the bottom bracket crankshaft 7, which is coaxial to the central axis M of the bottom bracket gear. Another difference between the bottom bracket gear and the Fig. 1 is that an output shaft 10 of the electric machine 1 is driven by means of a Fig. 2 is operatively connected to the sun gear of the planetary gear set PS1. Fig. In the bottom bracket gear shown in Figure 1, the electric motor is directly connected to the planetary gear set, i.e., without an intermediate belt drive or spur gear stage. The electric motor 1, the planetary gear set, and the gearbox 2 are arranged in a cavity of a bottom bracket shell 11, with the gearbox 2 and the planetary gear set arranged coaxially with the bottom bracket crankshaft 3.

[0044] Fig. Figure 3 shows the values ​​of the stationary gear ratios for the three planetary gear sets PS1, PS2, and PS3 of the bottom bracket transmission according to the second exemplary embodiment. All planetary gear sets have the same stationary gear ratio of -1.62. The stationary gear ratio corresponds to the negative ratio of the number of teeth between the ring gear and the sun gear.

[0045] Fig. 4 shows a switching matrix of the Fig. 1 and Fig. 2 of the bottom bracket transmission according to the invention according to the second exemplary embodiment. Furthermore, the table shows the values ​​for the transmission ratio "i" and the values ​​for the gear steps "phi." The ratio i represents the torque ratio of the manual transmission output shaft 4 to the torque applied to the carrier of the planetary gear set PS1. The ratios are valid under the assumption that the sun gear of the planetary gear set is braked, for example, by support from the electric motor. The torque ratio is independent of the prevailing speeds. Due to the speed superposition with the electric motor, the speed ratio is variable.

[0046] The gear ratios are valid under the assumption that the sun gear of the PS1 planetary gear set is braked, for example, by support from the electric motor. The shifting elements are actuated by a suitable actuator not shown in the figures; the letter "X" indicates that the respective shifting element is closed.

[0047] In a first gear, the first shift element S1 and the fourth shift element S4 are closed, with the remaining shift elements being open. A gear change from first to second gear occurs by opening the first shift element S1 and closing the second shift element S2. A gear change from second to third gear occurs by opening the fourth and second shift elements S4, S2 and by closing the first and third shift elements S1, S3, with the remaining shift elements being open. A shift from third to fourth gear occurs by opening the first shift element S1 and closing the second shift element S2, with the remaining shift elements being open.

[0048] The Fig. The bottom bracket gear shown in Figure 5 according to a third embodiment differs from that shown in Fig. 2 shown bottom bracket gear according to the second embodiment in the interconnection of the individual components of the gearbox.

[0049] The manual transmission input shaft 3 is rotationally fixedly connected to the carrier of the first planetary gear set PS2. The sun gear of the first planetary gear set PS2 is rotationally fixedly connected to the shaft 6. The ring gear of the first planetary gear set PS2 is rotationally fixedly connected to the transmission housing 5 by means of the second shifting element S2. Furthermore, the ring gear of the first planetary gear set PS2 is rotationally fixedly connected to the shaft 6 by means of the first shifting element S1. The ring gear of the second planetary gear set PS3 is also rotationally fixedly connected to the shaft 6, with the shaft 6 being rotationally fixedly connected to the sun gear of the second planetary gear set PS3 by means of the third shifting element S3. Furthermore, the sun gear of the second planetary gear set PS3 is rotationally fixedly connected to the transmission housing 5 by means of the fourth shifting element S4. The carrier of the second planetary gear set PS3 is rotationally fixedly connected to the manual transmission output shaft 4.

[0050] Fig. 6 shows the values ​​of the stand translation for the Fig. 5 shows the bottom bracket gear according to the third embodiment. In this embodiment, too, all planetary gear sets have a stationary gear ratio of -1.62.

[0051] Fig. 7 shows the switching matrix of the Fig. 5 illustrated bottom bracket gear according to the third embodiment, the gear ratio “i” and the gear step “phi”.

[0052] A first gear is achieved by closing the first switching element S1 and the fourth switching element S4, with the remaining switching elements open. A change from first to second gear occurs by opening the fourth switching element S4 and closing the third switching element S3, with the remaining switching elements open. Third gear is achieved by closing the second switching element S2 and the fourth switching element S4, with the remaining switching elements open. A change from third gear to fourth gear occurs by opening the fourth switching element S4 and closing the third switching element S3, with the remaining switching elements open.

[0053] The ratio in first gear is 1 because the planetary gear set speeds up and then the second planetary gear set slows down by the same number. Reference symbol 1 electric machine 2 manual transmissions 3 Manual transmission input shaft 4 Manual transmission output shaft 5 Gearbox housing 6 Wave 7 Bottom bracket crankshaft 8 traction mechanism carriers 9 pedals 10 Output shaft 11 Bottom bracket shell M central axis PS1 planetary gear set PS2 first planetary set PS3 second planetary gear set

Claims

[1] Bottom bracket gear for a bicycle, with a planetary gear set (PS1), an electric machine (1) and a manual transmission (2) which has a manual transmission input shaft (3) and a manual transmission output shaft (4), wherein a sun gear of the planetary gear set (PS1) is operatively connected or operatively connectable to the electric machine (1), a web of the planetary gear set (PS1) is rotatably connected to a bottom bracket crankshaft (7) and a ring gear of the planetary gear set (PS1) is rotatably connected to the manual transmission input shaft (3), characterized by that the gearbox output shaft (4) is connected in a rotationally fixed manner to a traction mechanism carrier (8) of the bottom bracket gearbox. [2] Bottom bracket gear according to claim 1, characterized bythat the manual transmission (2) has a first planetary gear set (PS2) and a second planetary gear set (PS3), wherein the first planetary gear set (PS2) is operatively connected to the manual transmission input shaft (3) and the second planetary gear set (PS3) is operatively connected to a manual transmission output shaft (4). [3] Bottom bracket gear according to claim 2, characterized by , that a. with the first planetary gear set (PS2) at least two, in particular exactly two gears, can be realized and / or that b. with the second planetary gear set (PS3) at least two, in particular exactly two gears, can be realized. [4] Bottom bracket gear claim 2 or 3, characterized by , that a. in the first planetary gear set (PS2) a first gear is a direct gear and a second gear is a transmission ratio and / or that b. in the second planetary gear set (PS3) the first gear is a slow gear and the second gear is a direct gear. [5] Bottom bracket gear according to one of claims 2 to 4, characterized by , that a. the manual transmission (2) has a first shift element (S1) by means of which two components of the first planetary gear set (PS2) can be connected to one another in a rotationally fixed manner and / or that b. the manual transmission (2) has a second shifting element (S2) by means of which a component of the first planetary gear set (PS2) can be connected in a rotationally fixed manner to a transmission housing (5). [6] Bottom bracket gear according to one of claims 2 to 5, characterized by , that a. the manual transmission (2) has a third shift element (S3) by means of which two components of the second planetary gear set (PS3) can be connected to one another in a rotationally fixed manner and / or that b. the manual transmission (2) has a fourth shifting element (S4) which can be connected in a rotationally fixed manner to a transmission housing (5) by means of a component of the second planetary gear set (PS3). [7] Bottom bracket gear according to claim 6, characterized by , that a sun gear of the first planetary gear set (PS2) is rotatably connected to the transmission housing (5) by means of the second shifting element (S2), and a web of the first planetary gear set (PS2) is rotatably connected to the manual transmission input shaft (3), and a ring gear of the first planetary gear set (PS2) is rotatably connected to a shaft (6), and a sun gear of the second planetary gear set (PS3) is connected in a rotationally fixed manner to the shaft (6), a web of the second planetary gear set (PS3) is connected in a rotationally fixed manner to the manual transmission output shaft (4), and a ring gear of the second planetary gear set (PS3) is rotatably connected to the transmission housing (5) by means of the fourth shifting element (S4). [8] Bottom bracket gear according to claim 7, characterized by , that a. the sun gear of the first planetary gear set (PS2) can be connected to the shaft (6) in a rotationally fixed manner by means of the first switching element (S1) and / or that b. the ring gear of the second planetary gear set (PS3) can be connected in a rotationally fixed manner to the shaft (6) by means of the third switching element (S3). [9] Bottom bracket gear according to one of claims 2 to 6, characterized by , that a sun gear of the first planetary gear set (PS2) is connected in a rotationally fixed manner to a shaft (6) and a web of the first planetary gear set (PS2) is connected in a rotationally fixed manner to the manual transmission input shaft (3) and a ring gear of the first planetary gear set (PS2) is rotatably connected to the transmission housing (5) by means of the second shifting element (S2) and a sun gear of the second planetary gear set (PS3) is rotatably connected to the transmission housing (5) by means of the fourth shifting element (S4), and a web of the second planetary gear set (PS3) is rotatably connected to the manual transmission output shaft (4), and a ring gear of the second planetary gear set (PS3) is rotatably connected to the shaft (6). [10] Bottom bracket gear according to claim 9, characterized by , that a. the ring gear of the first planetary gear set (PS2) can be connected to the shaft (6) in a rotationally fixed manner by means of the first switching element (S1) and / or that b. the sun gear of the second planetary gear set (PS3) can be connected in a rotationally fixed manner to the shaft (6) by means of the third switching element (S3). [11] Bottom bracket gear according to one of claims 1 to 10, characterized by that the electric machine (1) is arranged offset to a central axis (M) of the bottom bracket gear. [12] Bottom bracket with a bottom bracket crankshaft (7) and a bottom bracket gear according to one of claims 1 to 11, characterized by that the web of the first planetary gear set (PS1) is connected to the bottom bracket crankshaft (7) in a rotationally fixed manner. [13] Bottom bracket according to claim 12, characterized by a bottom bracket shell (11), wherein the bottom bracket gear is arranged within a cavity of the bottom bracket shell (11). [14] Bicycle with a bottom bracket gear according to one of claims 1 to 11 or a bottom bracket according to claim 12 or 13.

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