Planetary bottom bracket gearbox for a bicycle or e-bike

Abstract

A planetary bottom bracket gearbox for a bicycle or pedelec (1) is proposed, comprising a crankshaft (WAn) as the input and a gearbox output shaft (WAb) as the output, as well as further shafts (W1, W2, W3, W4, W5), with three planetary gear sets (RS1, RS2, RS3), and with six shift elements (B1, B2, B3, K1, K1I, K2, K3) for implementing multiple gears (G1, G2, G3, G4, G5, G6, G7, G8). Furthermore, a bicycle or pedelec (1) with a bottom bracket gearbox is proposed.

Description

The present invention relates to a bottom bracket transmission of planetary design for a bicycle or a pedelec with a bottom crank shaft as drive and a transmission output shaft as output as well as further shafts, with three planetary gear sets, and with six shift elements for realizing multiple gears. The invention further relates to a bicycle or pedelec with the bottom bracket transmission.For example, from the publication DE 10 2022 207 262 B3 a bottom bracket transmission of planetary construction for a bicycle or a pedelec is known. The bottom bracket transmission has a crank shaft as the drive and a transmission output shaft as the output and at least five further shafts, wherein the output is preferably effected via a sprocket, a belt wheel or the like. Furthermore, the bottom bracket transmission comprises three planetary gear sets which are arranged coaxially with the crank shaft, and six shift elements for realizing at least eight gears in the bottom bracket transmission. In addition, a first partial transmission with a first planetary gear set is provided, wherein a first shift element and a fourth shift element are assigned to the first partial transmission. Furthermore, a second subtransmission with a second planetary gear set and a third planetary gear set is provided as a positive planetary gear set, wherein a second shift element, a third shift element, a fifth shift element and a sixth shift element are assigned to the second subtransmission. To block the first planetary gear set, two elements of the first planetary gear set can be connected to one another via the fourth shift element.DE 10 2022 203 240 B3 and DE 10 2022 206 682 B3 disclose a bottom bracket transmission of planetary design for bicycles or pedelecs, which comprises a crank shaft as drive, a transmission output shaft as output, at least four further shafts, three planetary gear sets and five shift elements in order to realize at least six gears.DE 10 2022 209 135 B3 (post-published) discloses a bottom bracket transmission of planetary design for bicycles or pedelecs, which comprises a crank shaft as drive, a transmission output shaft as output, at least four further shafts, three planetary gear sets and five shift elements in order to realize at least five gears.The object of the present invention is to propose a bottom bracket transmission and a bicycle or pedelec with the bottom bracket transmission, which have the smallest possible construction outlay with properties improved compared to the prior art.This object is achieved according to the invention by the subject matter having the features of patent claim 1 or 14. Advantageous and claimed developments are evident from the dependent claims and the description and the drawings.Thus, a bottom bracket transmission of planetary construction for a bicycle or a pedelec is proposed. The bottom bracket transmission has a crank shaft as the drive and a transmission output shaft as the output and further shafts, wherein the output is preferably effected via a sprocket, a belt wheel or the like. Furthermore, the bottom bracket transmission comprises three planetary gear sets, and six shift elements for realizing, for example, eight gears in the proposed bottom bracket transmission, wherein at least one second planetary gear set is designed as a plus planetary gear set. In order to realize a particularly effective and space-saving embodiment in the bottom bracket transmission, the crank shaft is connected to a second element of a first planetary gear set, wherein the transmission output shaft is connected to a third element of a third planetary gear set, wherein a third element of the first planetary gear set is connected to a second element of the third planetary gear set, wherein a first element of the first planetary gear set is fixable via a first shifting element to a housing or to a stationary component or the like, wherein a planetary gear carrier of the second planetary gear set is fixable via a second shifting element to the housing and is connectable via a fifth shifting element to the second element of the first planetary gear set, wherein a sun gear of the second planetary gear set is connected to a first element of the third planetary gear set, wherein a ring gear of the second planetary gear set is fixable to the housing via a third shift element and is connectable to the third element of the third planetary gear set and to the transmission output shaft via a sixth shift element, and wherein two elements of the first planetary gear set are connectable to one another via a fourth shift element for blocking the first planetary gear set.In this way, with the above-described connection, in the proposed bottom bracket transmission with only three planetary gear sets provided and only six shift elements provided, a particularly simple and compact construction is realized in the bottom bracket transmission. In addition, particularly low component loads and an advantageously high gearing efficiency arise due to the geometric transmission range in the bottom bracket transmission.For the mechanical connection of elements, for example rotating elements or the like of the planetary gear sets, preferably, in addition to the drive and output, further shafts or shaft-like elements are used, wherein the term shaft is not to be understood exclusively as a cylindrical, rotatably mounted machine element for transmitting torques, but rather also to be understood as general connecting elements which connect the individual gear set elements to one another for transmitting torque.In the first planetary gear set of the proposed bottom bracket transmission, different blocking variants are possible via the fourth shift element, which is preferably designed as a freewheel, in two different arrangement variants of the fourth shift element.Within the scope of a first blocking variant of the first planetary gear set, it is provided that the first element of the first planetary gear set, when the fourth shift element is locked, can be connected in a first arrangement variant to the second element of the first planetary gear set.In a second blocking variant of the first planetary gear set, it is provided that the second element of the first planetary gear set, when the fourth shift element is locked, can be connected to the third element of the first planetary gear set in a second arrangement variant.Independently of the blocking variants, the bottom bracket transmission provides that the crank shaft is connected to the second element of the first planetary gear set, that the transmission output shaft is connected to the third element of the third planetary gear set, that the third element of the first planetary gear set is firmly connected to the second element of the third planetary gear set via a fourth shaft, that the first element of the first planetary gear set is fixable to the housing via a first shaft when the first shift element is closed, that the planet carrier of the second planetary gear set is fixable to the housing via a second shaft when the second shift element is locked and is connectable to the second element of the first planetary gear set when the fifth shift element is closed, that the sun gear of the second planetary gear set is connected to the first element of the third planetary gear set via a fifth shaft, and in that the ring gear of the second planetary gear set can be fixed on the housing via a third shaft when the third shift element is closed and can be connected to the third element of the third planetary gear set and to the transmission output shaft when the sixth shift element is locked.In the proposed bottom bracket transmission, it is provided that the shift elements can be designed as brakes, freewheel brakes, clutches and / or freewheels. An advantageous variant of the invention provides that the first shifting element and the third shifting element are each designed as a form-fit brake, that the second shifting element is designed as a free-wheeling brake, that the fourth shifting element and the sixth shifting element are each designed as a free-wheeling clutch, and / or that the fifth shifting element is designed as a form-fit clutch.The shifting elements embodied as brakes and clutches are preferably embodied as form-locking shifting elements, for example as cost-effective brake claws or shifting claws or the like, for example with a toothed brake ring and a corresponding pawl. Brakes as shift elements have the advantage that they can be easily reached for actuation from the outside. In the case of clutches designed as freewheels, it is advantageous if the brakes are designed, for example, as one-way brakes, in order to prevent the transmission from blocking when the direction of rotation is reversed at the input or at the output. Preferably, non-actively switchable or actuatable freewheels are used as freewheels. This has the advantage that no switching actuation is required in the passive switching elements. The non-operable one-way clutch transmits a torque when it locks in the lock-up direction state. No torque is transmitted in the opposite direction of rotation, since the freewheel does not block in the overrun drive state. However, it is conceivable that actively switchable freewheels or also actively switchable freewheel brakes are also used.A preferred embodiment of the invention can provide that at least one of the planetary gear sets provided is designed as a minus planetary gear set, resulting in an arrangement which is particularly advantageous in terms of installation space. It is also conceivable that, in addition to the second planetary gear set, further planetary gear sets are also designed as a plus planetary gear set.A minus planetary gear set can preferably be transferred into a plus planetary gear set if the planetary gear carrier and ring gear connection on this gear set is interchanged with one another and the amount of the stationary transmission ratio is increased by 1. A minus planetary gear set has planetary gears rotatably mounted on its planetary gear carrier, which mesh with the sun gear and the ring gear of this planetary gear set, so that the ring gear rotates in the direction opposite to the sun gear rotation direction when the planetary gear carrier is held stationary and the sun gear rotates. A plus planetary gear set has inner and outer planetary gears rotatably mounted on its planetary gear carrier and in meshing engagement with one another, wherein the sun gear of this planetary gear set meshes with the inner planetary gears and the ring gear of this planetary gear set meshes with the outer planetary gears, so that the ring gear rotates in the same direction of rotation as the sun gear direction when the planetary gear carrier is held stationary and the sun gear rotates.This means for the person skilled in the art that in the individual gearsets designed as minus planetary gearsets, a first element or gearset element is designed as a sun gear, a second element is designed as a planet carrier or carrier, and a third element is designed as a ring gear. Furthermore, this means that in an individual gearset designed as a plus planetary gearset, the first element is designed as a sun gear, the second element is designed as a ring gear, and the third element is designed as a planet carrier or carrier.Furthermore, in the proposed bottom bracket transmission, it is conceivable that stepped planets are used both in a minus planetary gear set and in a plus planetary gear set. In the case of a minus stepped planetary gear set, the assignment of the elements or the gear set elements is maintained as in the case of a conventional minus planetary gear set. In a positive stepped planetary gearset, it is provided that the first element is designed as a first sun gear, the second element as a second sun gear and the third element as a planet carrier, or that the first element is designed as a first ring gear, the second element as a second ring gear and the third element as a planet carrier.In order to further optimize the control of the proposed bottom bracket transmission, it is provided that at least one torque sensor or the like is provided on the drive and / or on the output.In order to electrically support the drive in the proposed bottom bracket transmission, at least one electric machine or the like can be connected or connectable or permanently or releasably coupled to the drive or to the crank shaft or transmission input shaft and / or to the output or to the transmission output shaft. The electric machine can preferably be arranged axially parallel to the pedal crankshaft or transmission input shaft, while the planetary gear sets are arranged coaxially to the pedal crankshaft or transmission input shaft.A further aspect of the present invention claims a bicycle or pedelec with the above-described bottom bracket transmission. This results in the advantages and further advantages already described.The present invention is explained in more detail below with reference to the drawings.The following are shown: FIG. 1 shows a schematic principal view of a bottom bracket transmission according to the invention on a bicycle or a pedelec with a first locking variant of a first planetary gear set; FIG. 2 shows a schematic principal view of the bottom bracket transmission with a second locking variant of the first planetary gear set; FIG. 3 shows a shift pattern with eight shiftable gears of the bottom bracket transmission; FIG. 4 shows a schematic basic view of a planetary gear set as a minus planetary gear set; FIG. 5 shows a schematic basic view of a planetary gear set as a plus planetary gear set; FIG. 6 shows a schematic basic view of a planetary gear set as a minus stepped planetary gear set; FIG. 7 shows a schematic basic view of a planetary gear set as a plus stepped planetary gear set with two sun gears; FIG. 8 shows a schematic basic view of a planetary gear set as a plus stepped planetary gear set with two ring gears; FIG. 9 shows a schematic basic view of the bottom bracket transmission according to FIG. 1 with a torque sensor on the drive indicated by way of example; FIG. 10 shows a schematic basic view of the bottom bracket transmission according to FIG. 9 with an electric machine arranged by way of example on the drive; FIG. 11 shows a schematic basic view of the bottom bracket transmission according to FIG. 9 with an electric machine arranged by way of example on the output; and FIG. 12 shows a schematic basic view of the pedal bearing transmission according to FIG. 9 with a freewheel provided between the pedal crankshaft and the transmission input shaft.FIGS. 1 to 12 show various embodiments and designs or a shift pattern of a bottom bracket transmission according to the invention in planetary construction only by way of example. FIG. 1 shows, by way of example, a bicycle or pedelec 1 with the bottom bracket transmission, which is only indicated schematically.The pedal transmission is shown in a housing or pedal housing 2 with a pedal crankshaft or pedal crank with pedals, wherein the pedal crankshaft WAn is connected to the transmission input of the pedal transmission. Furthermore, the bottom bracket transmission comprises a transmission output shaft WAb as output with a chain wheel or belt wheel, not shown in any more detail. The bottom bracket transmission comprises a first planetary gear set RS 1 and a second planetary gear set RS 2 as well as a third planetary gear set RS 3, to which a first shift element B 1, a second shift element B 2, a third shift element B 3, a fourth shift element K 1, K 1 I, a fifth shift element K 2 and a sixth shift element K 3 are assigned.Independently of the respective variant embodiments, the bottom bracket transmission provides for the crankshaft WAn to be connected to a second element of the first planetary gear set RS 1, for the transmission output shaft WAb to be connected to a third element of the third planetary gear set RS 3, for a third element of the first planetary gear set RS 1 to be connected to a second element of the third planetary gear set RS 3, for a first element of the first planetary gear set RS 1 to be fixable to a housing 2 via the first shifting element B 1, for a planetary gear carrier PT 2 of the second planetary gear set RS 2 to be fixable to the housing 2 via the second shifting element B 2 and for it to be connectable to the second element of the first planetary gear set RS 1 via the fifth shifting element K 2, a sun gear SR2 of the second planetary gear set RS2 is connected to a first element of the third planetary gear set RS3, a ring gear HR2 of the second planetary gear set RS2 can be fixed to the housing 2 via the third shifting element B3 and can be connected to the third element of the third planetary gear set RS3 and to the transmission output shaft WAb via the sixth shifting element K3, and two elements of the first planetary gear set RS1 can be connected to one another in I via the fourth shifting element K1 I, K1.In FIGS. 1 and 2 and also 9 to 12, the first and third planetary gear sets RS 1, RS 3 are each designed as minus planetary gear sets which are advantageous in terms of installation space. In this case, it is provided that a sun gear SR 1, SR 3 is provided as the first element, a carrier or planet carrier PT 1, PT 3 is provided as the second element, and a ring gear HR 1, HR 3 is provided as the third element in the two planetary gear sets RS 1, RS 3. The second planetary gear set is designed as a plus planetary gear set with a sun gear SR 2, a planet carrier PT 2 and a ring gear HR 2.FIG. 1 shows a first blocking variant of the first planetary gear set RS 1 in the bottom bracket transmission, wherein it is provided in detail that the crank shaft WAn is connected to the planet carrier PT 1 of the first planetary gear set RS 1, that the transmission output shaft WAb is connected to the ring gear HR 3 of the third planetary gear set RS 3, that the ring gear HR 1 of the first planetary gear set RS 1 is firmly connected to the planet carrier PT 3 of the third planetary gear set RS 3 via a fourth shaft W 4, that the sun gear SR 1 of the first planetary gear set RS 1 is firmly fixable to the housing 2 via a first shaft W 1 when the first shift element B 1 is closed, the planet carrier PT2 of the second planetary gear set RS2 can be fixed to the housing 2 via a second shaft W2 when the second shift element B2 is locked and can be connected to the planet carrier PT1 of the first planetary gear set RS1 when the fifth shift element K2 is closed, the sun gear SR2 of the second planetary gear set RS2 is connected to the sun gear SR3 of the third planetary gear set RS3 via a fifth shaft W5, the ring gear HR2 of the second planetary gear set RS2 can be fixed to the housing 2 via a third shaft W3 when the third shift element B3 is closed and can be connected to the ring gear HR3 of the third planetary gear set RS3 and to the transmission output shaft WAb when the sixth shift element K3 is locked, and in that, for blocking the first planetary gear set RS 1 as a first blocking variant, the sun gear SR 1 of the first planetary gear set RS 1 is connected to the planet carrier PT 1 of the first planetary gear set RS 1 when the fourth shift element K 1 is blocked in the first arrangement variant of the fourth shift element K 1.FIG. 2 shows a second locking variant of the first planetary gear set RS 1 in the bottom bracket transmission. In contrast to the embodiment shown in FIG. 1, it is provided that, for blocking the first planetary gear set RS 1 as a second blocking variant, the ring gear HR 1 of the first planetary gear set RS 1 is connected in I with the fourth shift element K 1 I locked in the second arrangement variant of the fourth shift element K 1 to the planet carrier PT 1 of the first planetary gear set RS 1.FIG. 3 shows a shift pattern for the bottom bracket transmission as an eight-speed transmission, so that a total of eight gears G 1, G 2, G 3, G 4, G 5, G 6, G 7, G 8 are realized. The shift pattern specifies the shift elements B 1, B 2, B 3, K 1, K 1 I, K 2, K 3 used for the respective gear G 1, G 2, G 3, G 4, G 5, G 6, G 7, G 8. Here, an X in the freewheels K 1, K 1 I, K 3 and in the freewheel brake B 2 as shift elements in the shift pattern means that the freewheels K 1, K 1 I, K 3 and the freewheel brake B 2 block. This works automatically without external actuation. Further, in a brake B 1, B 3 and a clutch K 2 as a shift element in the shift pattern, an X means that the brake B 1, B 3 and the clutch K 2 are closed. This functions via a suitable actuator system.In detail, it follows from the shift pattern according to FIG. 3 that, for the realization or shifting of a first gear G 1, the second shift element B 2 designed as a freewheel brake, the fourth shift element K 1, K 1 I designed as a freewheel and the sixth shift element K 3 designed as a freewheel are locked, that, for the realization of a second gear G 2, the fourth shift element K 1, K 1 I designed as a freewheel and the sixth shift element K 3 designed as a freewheel are locked, and the fifth shift element K 2 designed as a clutch is closed, that, for the realization of a third gear G 3, the first shift element B 1 designed as a brake is closed and the second shift element B 2 designed as a freewheel brake is locked, and the sixth shift element K 3 designed as a freewheel is locked, wherein, for the realization of a fourth gear G4, the first shift element B1 designed as a brake is closed and the fifth shift element K2 designed as a clutch is closed and the sixth shift element K3 designed as a freewheel is locked, that for the realization of a fifth gear G5, the second shift element B2 designed as a freewheel brake is locked and the third shift element B3 designed as a brake is closed and the fourth shift element K1, K1 I designed as a freewheel is locked, that for the realization of a sixth gear G6, the third shift element B3 designed as a brake is closed and the fourth shift element K1, K1 I designed as a freewheel is locked and the fifth shift element K2 designed as a clutch is closed, wherein, for realizing a seventh gear G 7, the first shifting element B 1 embodied as a brake and the third shifting element B 3 embodied as a brake are closed and the second shifting element B 2 embodied as a freewheel brake is locked, and / or wherein, for realizing an eighth gear G 8, the first shifting element B 1 embodied as a brake, the third shifting element B 3 embodied as a brake and the fifth shifting element K 2 embodied as a clutch are closed.FIG. 4 shows, by way of example, a minus planetary gear set in which the first element is designed as a sun gear 1-SR, the second element is designed as a planet carrier 2-PT and the third element is designed as a ring gear 3-HR.FIG. 5 shows, by way of example, a plus planetary gear set in which the first element is designed as a sun gear 1-SR, the second element is designed as a ring gear 2-HR and the third element is designed as a planet carrier 3-PT.FIG. 6 shows, by way of example, a minus stepped planetary gearset in which the first element is designed as a sun gear 1-SR, the second element as a planet carrier 2-PT and the third element as a ring gear 3-HR.FIG. 7 shows, by way of example, a plus stepped planetary gearset in which the first element is designed as a first sun gear 1-SRA, the second element as a second sun gear 2-SRB and the third element as a planet carrier 3-PT.FIG. 8 shows, by way of example, a further embodiment of a positive stepped planetary gearset in which the first element is designed as a first ring gear 1-HRA, the second element as a second ring gear 2-HRB and the third element as a planet carrier 3-PT.The possible embodiments illustrated in FIGS. 4 to 8 with reference to a planetary gear set can be implemented on the specific planetary gear sets RS 1, RS 2, RS 3 of the bottom bracket transmission according to the invention.FIG. 9 shows an embodiment of the bottom bracket transmission according to the invention with reference to FIG. 1, in which a torque sensor 3 is connected or connectable to the pedal crankshaft or to the transmission input shaft WAn. For example, a disk-shaped torque sensor 3 can be arranged at the transmission input. However, the torque sensor 3 can also be implemented in a different manner.FIGS. 10 and 11 each show an embodiment of the bottom bracket transmission according to the invention with an additional electric machine EM on the basis of FIG. 9. The electric machine EM can be connected to the pedal crankshaft WAn, as is indicated in FIG. 10. It is also conceivable for the electric machine EM to be linked to the transmission output shaft WAb, as shown in FIG. 11. The electric machine EM is preferably arranged axially parallel to the pedal crankshaft or transmission input shaft WAn. However, a coaxial arrangement of the electric machine EM with respect to the pedal crankshaft would also be possible. Independently of this, it is advantageous to connect the electric machine EM via a freewheel F 0 or the like, so that no losses are caused by the co-rotating electric machine EM during operation without the electric machine EM.FIG. 12 shows an embodiment of the bottom bracket transmission according to the invention with reference to FIG. 9 with an additional freewheel F 1 between the crank and the transmission input of the bottom bracket transmission. In this way, in the event of a pedaling interruption, the freewheel can open and decouple the pedal crank from the inertial masses of the gear wheel set and in particular of the electric machine EM, so that no mass forces can be perceptible at the pedal.Reference numerals denote reference numerals1 Bicycle or Pedelec 2 housing or bottom bracket housing 3 torque sensor EM electric machine F 0 freewheel for electric machine F 1 additional freewheel SR 1 sun gear of the first planetary gear set PT 1 planet carrier of the first planetary gear set HR 1 ring gear of the first planetary gear set SR 2 sun gear of the second planetary gear set PT 2 planet carrier of the second planetary gear set HR 2 ring gear of the second planetary gear set SR 3 sun gear of the third planetary gear set PT 3 planet carrier of the third planetary gear set HR 3 ring gear of the third planetary gear set RS 1 first planetary gear set RS 2 second planetary gear set RS 3 third planetary gear set WAn transmission input shaft or bottom crank shaft WAb transmission output shaft W 1 first shaft W 2 second shaft w3 third shaft W4 fourth shaft W5 fifth shaft G1 first gear of the bottom bracket transmission G2 second gear of the bottom bracket transmission G3 third gear of the bottom bracket transmission G4 fourth gear of the bottom bracket transmission G5 fifth gear of the bottom bracket transmission G6 sixth gear of the bottom bracket transmission G7 seventh gear of the bottom bracket transmission G8 eighth gear of the bottom bracket transmission B1 first shifting element B2 second shifting element B3 third shifting element K1 embodied as a brake in a first arrangement variant K1 I fourth shifting element embodied as a freewheel in a second arrangement variant K2 fifth shifting element as a clutch Shift element K 3 is embodied as a sixth shift element 1- SR embodied as a freewheel, first element as a sun gear 2- PT, second element as a planet carrier 2- HR, second element as a ring gear 3- HR, third element as a ring gear 3- PT, third element as a planet carrier 1- SRA, first element as a first sun gear 2- SRB, second element as a second sun gear 1- HRA, first element as a first ring gear 2- HRB, first element as a second ring gear

Claims

Bottom bracket transmission in planetary construction for a bicycle or a pedelec (1), having a crank shaft (WAn) as drive and a transmission output shaft (WAb) as output and further shafts (W1, W2, W3, W4, W5), having three planetary gear sets (RS1, RS2, RS3), and having six shift elements (B1, B2, B3, K1, K1 I, K2, K3) for realizing a plurality of gears (G1, G2, G3, G4, G5, G6, G7, G8), wherein at least one second planetary gear set (RS2) is designed as a plus planetary gear set, wherein the pedal crank shaft (WAn) is connected to a second element of a first planetary gear set (RS 1), wherein the transmission output shaft (WAb) is connected to a third element of a third planetary gear set (RS 3), wherein a third element of the first planetary gear set (RS 1) is connected to a second element of the third planetary gear set (RS 3), wherein a first element of the first planetary gear set (RS 1) is fixable to a housing (2) via a first shift element (B 1), wherein a planet carrier (PT2) of the second planetary gear set (RS2) is fixable to the housing (2) via a second shift element (B2) and is connectable to the second element of the first planetary gear set (RS1) via a fifth shift element (K2), wherein a sun gear (SR2) of the second planetary gear set (RS2) is connected to a first element of the third planetary gear set (RS3), wherein a ring gear (HR2) of the second planetary gear set (RS2) is fixable to the housing (2) via a third shift element (B3) and is connectable to the third element of the third planetary gear set (RS3) and to the transmission output shaft (WAb) via a sixth shift element (K3), and wherein, for blocking the first planetary gear set (RS 1), two elements of the first planetary gear set (RS 1) can be connected to one another via a fourth shift element (K 1 I, K 1 I).Bottom bracket transmission according to Claim 1, characterized in that, in a first locking variant of the first planetary gear set (RS1), the first element of the first planetary gear set (RS1) can be connected, when the fourth shift element (K1) is locked, in a first arrangement variant to the second element of the first planetary gear set (RS1).Bottom bracket transmission according to Claim 1, characterized in that, in a second blocking variant of the first planetary gear set (RS1), the second element of the first planetary gear set (RS1) can be connected, when the fourth shift element (K1 I) is blocked, in a second arrangement variant to the third element of the first planetary gear set (RS1).Bottom bracket transmission according to one of the preceding claims, characterized in that the crank shaft (WAn) is connected to the second element of the first planetary gear set (RS1), in that the transmission output shaft (WAb) is connected to the third element of the third planetary gear set (RS3), in that the third element of the first planetary gear set (RS1) is fixedly connected to the second element of the third planetary gear set (RS3) via a fourth shaft (W4), in that the first element of the first planetary gear set (RS1) can be fixed to the housing (2) via a first shaft (W1) when the first shift element (B1) is closed, the planet carrier (PT2) of the second planetary gear set (RS2) can be fixed to the housing (2) via a second shaft (W2) when the second shift element (B2) is locked, and can be connected to the second element of the first planetary gear set (RS1) when the fifth shift element (K2) is closed, the sun gear (SR2) of the second planetary gear set (RS2) being connected to the first element of the third planetary gear set (RS3) via a fifth shaft (W5), and in that the ring gear (HR2) of the second planetary gear set (RS2) can be fixed to the housing (2) via a third shaft (W3) when the third shift element (B3) is closed and can be connected to the third element of the third planetary gear set (RS3) and to the transmission output shaft (WAb) when the sixth shift element (K3) is locked.Pedal transmission according to one of the preceding claims, characterized in that the first shifting element (B1) and the third shifting element (B3) are each designed as a positive-locking brake, in that the second shifting element (B2) is designed as a free-wheeling brake, in that the fourth shifting element (K1, K1 I) and the sixth shifting element (K3) are each designed as a free-wheeling clutch, and / or in that the fifth shifting element (K2) is designed as a positive-locking clutch.Bottom bracket transmission according to one of the preceding claims, characterized in that the first planetary gear set (RS1) and / or the third planetary gear set (RS3) is designed as a minus planetary gear set.Pedal transmission according to Claim 6, characterized in that, in the case of a minus planetary gear set, the first element is designed as a sun wheel (SR1, SR3), the second element is designed as a planet wheel carrier (PT1, PT3) and the third element is designed as a ring wheel (HR1, HR2).Bottom bracket transmission according to one of the preceding claims, characterized in that the first planetary gear set (RS1) and / or the third planetary gear set (RS3) is designed as a plus planetary gear set.Pedal transmission according to Claim 8, characterized in that, in the case of a positive planetary gear set, the first element is designed as a sun wheel (SR1, SR3), the second element is designed as a ring wheel (HR1, HR3) and the third element is designed as a planet wheel carrier (PT1, PT3).Pedal transmission according to one of the preceding claims, characterized in that a torque sensor (3) is connected to the pedal crankshaft (WAn).Pedal transmission according to one of the preceding claims, characterized in that at least one electric machine (EM) is connected or can be connected to the pedal crankshaft (WAn) or to the transmission output shaft (WAb).Pedal bearing transmission according to Claim 11, characterized in that the electric machine (EM) is arranged axially parallel to the pedal crankshaft (WAn).Pedal transmission according to one of the preceding claims, characterized in that, in order to realize a first gear (G1), the second shift element (B2) designed as a freewheel brake, the fourth shift element (K1, K1 I) designed as a freewheel and the sixth shift element (K3) designed as a freewheel are blocked, in that, in order to realize a second gear (G2), the fourth shift element (K1, K1 I) designed as a freewheel and the sixth shift element (K3) designed as a freewheel are blocked, and the fifth shift element (K2) designed as a clutch is closed, wherein, for realizing a third gear (G3), the first shift element (B1), which is designed as a brake, is closed and the second shift element (B2), which is designed as a free-wheeling brake, is blocked and the sixth shift element (K3), which is designed as a free-wheeling brake, is blocked, that, for realizing a fourth gear (G4), the first shift element (B1), which is designed as a brake, is closed and the fifth shift element (K2), which is designed as a clutch, is closed and the sixth shift element (K3), which is designed as a free-wheeling clutch, is blocked, that, for realizing a fifth gear (G5), the second shift element (B2), which is designed as a free-wheeling brake, is blocked and the third shift element (B3), which is designed as a brake, is closed and the fourth shift element (K1, K1 I) is blocked, wherein, for realizing a sixth gear (G6), the third shifting element (B3) designed as a brake is closed and the fourth shifting element (K1, K1 designed as a freewheel is blocked I) and the fifth shifting element (K2) designed as a clutch is closed, wherein, for realizing a seventh gear (G7), the first shifting element (B1) designed as a brake and the third shifting element (B3) designed as a brake are closed and the second shifting element (B2) designed as a freewheel brake is blocked, and / or wherein, for realizing an eighth gear (G8), the first shifting element (B1) designed as a brake, the third shifting element (B3) designed as a brake and the fifth shifting element (K2) designed as a clutch are closed.Bicycle or pedelec (1) with the bottom bracket transmission according to one of the preceding claims.

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