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 drive, a gearbox output shaft (WAb) as the driven shaft, and further shafts (W1, W2, W3, W4, W5, W6), as well as a first gearbox switching group (3) and a second gearbox switching group (4), wherein the first gearbox switching group (3) comprises a first planetary gear set (RS1) and a second planetary gear set (RS2), to which four switching elements (B1, K1, K2, K3) are assigned, and wherein the second gearbox switching group (4) comprises at least a third planetary gear set (RS3). 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 construction for a bicycle or a pedelec having a transmission input shaft as drive and a transmission output shaft as output and having further shafts, and having a first transmission shift group and a second transmission shift group, to which a plurality of planetary gear sets and shift elements are assigned. The invention further relates to a bicycle or pedelec with the bottom bracket transmission.For example, from the publication DE 10 2021 204 634 B3, such a transmission in a pedal crank housing for a bicycle is known. The transmission comprises three planetary gear sets, to which four shift elements are assigned, in order to realize at least four gears.DE 10 2018 208 387 A1 discloses a multi-stage transmission of planetary design for a bicycle or a pedelec with a transmission input shaft as drive and a transmission output shaft as output, with at least four planetary gear sets, wherein at least four freewheel clutches and at least four brakes are provided for realizing at least sixteen gears.DE 10 2022 206 690 B3 discloses a bottom bracket transmission of planetary design for a bicycle or pedelec with a bottom bracket shaft as drive, a transmission output shaft as output, five shafts, three coaxially arranged planetary gear sets and six shift elements for realizing at least six gears.DE 10 2016 225 158 A1 relates to a transmission for a bicycle having a transmission input shaft which is connectable to a bottom bracket crankshaft in a rotationally fixed manner, as well as three planetary sets and an electric machine. The planetary sets are operatively connected to one another and can be connected to a transmission housing or to one another in a rotationally fixed manner by means of different shift elements in order to realize four gears.DE 10 2022 207 262 B3 relates to a bottom bracket transmission of planetary design for a bicycle or pedelec with a bottom bracket shaft as drive, a transmission output shaft as output, five shafts, three coaxially arranged planetary gear sets and six shift elements for realizing at least eight gears. A first subtransmission having a first planetary gear set and a second subtransmission having a second and third planetary gear set are provided.DE 10 2022 209 139 B3 (post-published) discloses a bottom bracket transmission of planetary design for a bicycle or pedelec with a bottom bracket shaft as drive, a transmission output shaft as output, four further shafts, three coaxially arranged planetary gear sets and five shift elements for realizing 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 claims 1 and 15, respectively. 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 a first transmission shift group and a second transmission shift group, wherein the first transmission shift group comprises a first planetary gear set and a second planetary gear set, to which four shift elements are assigned, wherein the second transmission shift group comprises at least one third planetary gear set, to which at least two shift elements are assigned, wherein a first shaft as input shaft of the first transmission shift group is connected to a second element of the first planetary gear set, wherein a fifth shaft as output shaft of the first transmission shift group is connectable via a third shift element to a third element of the first planetary gear set and to a third element of the second planetary gear set, wherein the third element of the first planetary gear set is fixedly connected to the third element of the second planetary gear set, wherein the fifth shaft is connectable via a fifth shift element to a second element of the second planetary gear set, wherein a first element of the first planetary gear set is fixable via a first shift element to a housing or to a stationary component or the like and is connectable via a fourth shift element to the second element of the second planetary gear set, and wherein a first element of the second planetary gear set is fixed to the housing.In this way, with the above-described connection of the first transmission shift group, in the proposed bottom bracket transmission with only two planetary gear sets provided and only four 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 toothing efficiency arise due to the geometric transmission range in the bottom bracket transmission compared to the known transmission.For the mechanical connection of elements, for example rotary elements or the like of the two planetary gear sets in the two transmission shift groups, 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 connection elements which connect the individual gear set elements to one another for transmitting torque.The axial sequence of the two transmission shift groups can be interchanged in the case of the proposed bottom bracket transmission. Consequently, the first transmission shift group is connected upstream or downstream of the second transmission shift group between the transmission input shaft or the crankshaft and the transmission output shaft of the bottom bracket transmission. In an upstream arrangement of the first transmission shift group, a pedal crank of the pedal bearing transmission connected to the transmission input shaft or pedal crankshaft is connected to the first shaft as a kind of input shaft of the first transmission shift group, and the fifth shaft of the first transmission shift group is connected on the input side to the second transmission shift group. It is possible for the pedal crankshaft and the first shaft to be embodied in one piece or in multiple pieces. In a downstream arrangement of the first transmission shift group, the first shaft is connected on the output side to the second transmission shift group and the fifth shaft of the first transmission shift group is connected to the transmission output shaft. It is possible for the transmission output shaft and the fifth shaft to be embodied in one piece or in multiple pieces.In the proposed bottom bracket transmission, an arbitrarily designed multi-stage second transmission shift group can be combined with the first transmission shift group as a treaded transmission. Preferably, the second transmission shift group can be designed as a two-speed transmission or two-speed group and the first transmission shift group as a four-speed transmission or four-speed group, so that, for example, an eight-speed transmission is realized as a bottom bracket transmission. However, other gear numbers can also be realized in the transmission shift groups, so that the bottom bracket transmission can also realize more or less than, for example, eight gears. Depending on the boundary conditions and requirements of the bottom bracket transmission, gears can also be omitted. In this way, the wheel set can be optimized to the required transmission ratios (gear jumps, spreading, etc.) or also to the type of shifting operations, as to how many shifting elements are involved.In order to connect the second transmission shift group, it can be provided, in order to achieve a particularly simple and compact structure of the bottom bracket transmission, that in the second transmission shift group, a second element of the third planetary gear set is connected to the pedal crankshaft or to the fifth shaft of the first transmission shift group, that a third element of the third planetary gear set can be fixed to the housing via a second shift element, and that a first element of the third planetary gear set is connected to the first shaft of the first transmission shift group or to the transmission output shaft.For blocking the third planetary gear set in the second transmission shift group, two elements of the third planetary gear set can be connected to one another via the sixth shift element, so that a total of three different blocking variants result.Within the scope of the invention, the connection of the bottom bracket transmission, in which the first transmission shift group is connected upstream of the second transmission shift group, results in the crank shaft being connected directly or via the first shaft to the second element of the first planetary gear set, the transmission output shaft being connected to the first element of the third planetary gear set, the first element of the first planetary gear set being fixable to the housing via a second shaft and via the first shift element and being connectable to the second element of the second planetary gear set via the fourth shift element and via a fourth shaft, and the first element of the second planetary gear set being fixed to the housing via a fixed housing connection, the second element of the third planetary gear set is connectable via the fifth shaft and via the third shift element and via a third shaft to the third element of the first planetary gear set and to the third element of the second planetary gear set and via the fifth shift element and via the fourth shaft to the second element of the second planetary gear set, wherein the third element of the first planetary gear set is connected via the third shaft to the third element of the second planetary gear set, and the third element of the third planetary gear set is fixable via a sixth shaft and via the second shift element to the housing and is connectable via the sixth shift element to block the third planetary gear set to the first element of the third planetary gear set.In addition, the connection of the proposed bottom bracket transmission, in which the second transmission shift group is connected upstream of the first transmission shift group, results in the crank shaft being connected to the second element of the third planetary gear set, in the transmission output shaft being connectable directly or via the fifth shaft and via the third shift element and via a third shaft to the third element of the first planetary gear set and to the third element of the second planetary gear set and via the fifth shift element and via the fourth shaft W 4 to the second element of the second planetary gear set, the third element of the first planetary gear set being connected via the third shaft to the third element of the second planetary gear set, the first element of the first planetary gear set is fixable to the housing via a second shaft and via the first shift element and is connectable to the second element of the second planetary gear set via the fourth shift element and via a fourth shaft, the first element of the second planetary gear set is fixed to the housing via a fixed housing connection, and the third element of the third planetary gear set is fixable to the housing via a sixth shaft and via the second shift element and is connectable to the first element of the third planetary gear set via the sixth shift element for blocking the third planetary gear set, wherein the first element of the third planetary gear set is connected to the second element of the first planetary gear set via the first shaft.Within the scope of the invention, it is provided in the proposed bottom bracket transmission with the two transmission shift groups that the shift elements provided 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 second shifting element are each designed as a form-fit brake, that the third shifting element is designed as a form-fit clutch, and / or that the fourth shifting element and the fifth shifting element and the sixth shifting element are each designed as a freewheel.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 for one of the planetary gear sets to be 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 basic view of a bottom bracket transmission according to the invention on a bicycle or a pedelec with a first transmission shift group connected upstream of a second transmission shift group; FIG. 2 shows a schematic basic view of the bottom bracket transmission according to the invention with the first transmission shift group connected downstream of the second transmission shift group; FIG. 3 shows a shift pattern with four shiftable gears of the first transmission shift group in 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 with an embodiment of the second transmission shift group, connected downstream of the first transmission shift group as a four-speed transmission, as a two-speed transmission; FIG. 10 shows a schematic basic view of the bottom bracket transmission with an embodiment of the second transmission shift group, which is connected upstream of the first transmission shift group as a four-speed transmission, as a two-speed transmission; FIG. 11 shows a shift pattern of the eight-speed bottom bracket transmission according to FIGS. 9 and 10 ; FIG. 12 shows a schematic basic view of the bottom bracket transmission according to FIG. 9 with a torque sensor indicated by way of example on the drive; FIG. 13 shows a schematic basic view of the bottom bracket transmission according to FIG. 12 with an electric machine arranged by way of example on the drive; FIG. 14 shows a schematic basic view of the bottom bracket transmission according to FIG. 12 with an electric machine arranged by way of example on the output; and FIG. 15 shows a schematic basic view of the bottom bracket transmission according to FIG. 12 with a freewheel in front of the crank shaft.FIGS. 1 to 15 show various embodiments and designs or shift patterns 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 crank with pedals as a pedal crank shaft WAn, wherein the pedal crank shaft WAn is connected on the input side to one of the transmission shift groups 3, 4. Furthermore, the bottom bracket transmission comprises a transmission output shaft WAb as output with a not further illustrated chain wheel or belt wheel, which is connected on the output side to one of the transmission shift groups 3, 4. The bottom bracket transmission comprises a multi-stage first transmission shift group 3 and a multi-stage second transmission shift group 4, wherein the first transmission shift group 3 has a first planetary gear set RS 1 and a second planetary gear set RS 2, to which a first shift element B 1 as a form-locking brake, a third shift element K 1 as a form-locking clutch, a fourth shift element K 2 as a freewheel and a fifth shift element K 3 as a freewheel are assigned, and wherein the second transmission shift group 4 has a third planetary gear set RS 3, to which a second shift element B 2 as a form-locking brake and a sixth shift element K 4 as a freewheel are assigned. The two transmission shift groups 3, 4 form virtually two subtransmissions which can be interconnected with one another in any desired sequence with respect to the force flow direction between the pedal crankshaft WAn and the transmission output shaft WAb.Independently of the respective design variants, it is provided in the bottom bracket transmission that a first shaft W 1 as input shaft of the first transmission shift group 3 is connected to a second element of the first planetary gear set RS 1, that a fifth shaft W 5 as output shaft of the first transmission shift group 3 is connectable via a third shift element K 1 to a third element of the first planetary gear set RS 1 and to a third element of the second planetary gear set RS 2, wherein the third element of the first planetary gear set is fixedly connected to the third element of the second planetary gear set, that the fifth shaft W 5 is connected via a fifth shift element K 3 to a second element of the second planetary gear set RS 2, a first element of the first planetary gear set RS 1 is fixable to the housing 2 via a first shift element B 1 and is connectable to the second element of the second planetary gear set RS 2 via a fourth shift element K 2, and a first element of the second planetary gear set RS 2 is fixed to the housing 2.In FIGS. 1 and 2 and 9 and 10 and 12 to 15, the planetary gear sets RS 1, RS 2, RS 3 provided 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 2, SR 3 is provided as the first element, a carrier or planet carrier PT 1, PT 2, PT 3 is provided as the second element, and a ring gear HR 1, HR 2, HR 3 is provided as the third element in the planetary gear sets RS 1, RS 2, RS 3.FIG. 1 shows an embodiment variant of the bottom bracket transmission in which the first transmission shift group 3 is connected upstream of the second transmission shift group 4. In detail, in the first embodiment variant according to FIG. 1, it is provided that the first shaft W 1 as input shaft of the first transmission shift group 3 is connected to the pedal crankshaft WAn or is formed integrally therewith, that the first shaft W 1 is connected to the planet carrier PT 1 of the first planetary gear set RS 1, that the fifth shaft W 5 is connected on the input side to the second transmission shift group 4, that the fifth shaft W 5 as output shaft of the first transmission shift group 3 is connectable via a third shaft W 3 to the ring gear HR 1 of the first planetary gear set RS 1 and to the ring gear HR 2 of the second planetary gear set RS 2, when the third shift element K 1 is closed, wherein the ring gear HR1 of the first planetary gear set RS1 is connected via the third shaft W3 to the ring gear HR2 of the second planetary gear set RS2, that the fifth shaft W5 is connected via a fourth shaft W4 to the planet carrier PT2 of the second planetary gear set RS2 when the fifth shift element K3 is locked, that the sun gear SR1 of the first planetary gear set RS1 is fixable to the housing 2 via a second shaft W2 when the first shift element B1 is closed and is connectable to the planet carrier PT2 of the second planetary gear set RS2 when the fourth shift element K2 is locked and via the fourth shaft W4, and that the sun gear SR 2 of the second planetary gear set RS 2 is fixed to the housing 2 via a fixed housing connection W 0.FIG. 2 shows an embodiment variant of the bottom bracket transmission, in which the first transmission shift group 3 is arranged downstream of the second transmission shift group 4. In detail, in the embodiment variant according to FIG. 2, it is provided that the pedal crankshaft WAn is connected on the input side to the second transmission shift group 4, that the first shaft W 1 as the input shaft of the first transmission shift group 3 is connected on the output side to the second transmission shift group 4, that the first shaft W 1 is connected to the planet carrier PT 1 of the first planetary gear set RS 1, that the fifth shaft W 5 as the output shaft of the first transmission shift group 3 is connected to the transmission output shaft WAb or is formed integrally therewith, the fifth shaft W5 as output shaft of the first transmission shift group 3 is connectable, when the third shift element K1 is closed, via the third shaft W3 to the ring gear HR1 of the first planetary gear set RS1 and to the ring gear HR2 of the second planetary gear set RS2, the ring gear HR1 of the first planetary gear set RS1 being connected, via the third shaft W3, to the ring gear HR2 of the second planetary gear set RS2, and the fifth shaft W5 is connected, when the fifth shift element K3 is locked, via a fourth shaft W4 to the planet carrier PT2 of the second planetary gear set RS2, that the sun gear SR1 of the first planetary gear set RS1 can be fixed to the housing 2 via the second shaft W2 when the first shift element B1 is closed and can be connected to the planet carrier PT2 of the second planetary gear set RS2 via the fourth shaft W4 when the fourth shift element K2 is locked, and that the sun gear SR2 of the second planetary gear set RS2 is fixed to the housing 2 via a fixed housing connection W0.FIG. 3 shows a shift pattern for the first transmission shift group 3 as a four-speed transmission. This results in four gears V 1, V 2, V 3, V 4 being able to be realized by the first transmission shift group 3. The shift pattern specifies the shift elements B 1, K 1, K 2, K 3 used for the respective gear V 1, V 2, V 3, V 4. Here, an X in the freewheels K 2, K 3 as switching elements in the shift pattern means that the freewheels block. This works automatically without external actuation. Further, in a brake B 1 or a clutch K 1 as a shift element in the shift pattern, an X means that the brake B 1 or the clutch K 1 is closed. This functions via a suitable actuator system. An empty field in the freewheels K 2, K 3 means that they do not block. An empty field in the brake or clutch B 1, K 1 means that they are open.In detail, it follows from the shift pattern according to FIG. 3 that, for the realization or shifting of a first gear V 1, the fourth shift element K 2 designed as a free-wheeling mechanism and the fifth shift element K 3 designed as a free-wheeling mechanism block, that, for the shifting of a second gear V 2, the first shift element B 1 designed as a brake is closed and the fourth shift element K 2 designed as a free-wheeling mechanism blocks, that, for the shifting of a third gear V 3, the third shift element K 1 designed as a clutch is closed and the fourth shift element K 2 designed as a free-wheeling mechanism blocks, and / or that, for the shifting of a fourth gear V 4, the first shift element B 1 designed as a brake and the third shift element K 1 designed 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.FIGS. 9 and 10 show the bottom bracket transmission by way of example with a first transmission shift group 3 as a four-speed transmission group and with a second transmission shift group 4 as a two-speed transmission group. The two representations according to FIGS. 9 and 10 differ only in that the axial sequence of the two transmission shift groups 3, 4 is interchanged. In FIG. 9, the first transmission shift group 3 is connected upstream of the second transmission shift group 4, while in FIG. 10 the second transmission shift group 4 is connected upstream of the first transmission shift group 3.In detail, for the connection of the second transmission shift group 4 to the first transmission shift group 3 in FIG. 9, it is provided that, in the second transmission shift group 4, the planet carrier PT 3 of the third planetary gear set RS 3 is connected to the fifth shaft W 5 as output shaft of the first transmission shift group 3, that the ring gear HR 3 of the third planetary gear set RS 3 can be fixed to the housing 2 via a sixth shaft W 6 when the second shift element B 2 is closed, that the sun gear SR 3 of the third planetary gear set RS 3 is connected to the transmission output shaft WAb, and that, as one of the possible blocking variants of the third planetary gear set RS 3, the sun gear SR 3 of the third planetary gear set RS 3 is connected to the ring gear HR 3 of the third planetary gear set RS 3 when the sixth shift element K 4 is locked. The connections of the two planetary gear sets RS 1 and RS 2 in the first transmission shift group 3 have already been described above.In detail, for the connection of the second transmission shift group 4 to the first transmission shift group 3 in FIG. 10, it is provided that the planet carrier PT 3 of the third planetary gear set RS 3 is connected to the pedal crankshaft WAn, that the ring gear HR 3 of the third planetary gear set RS 3 can be fixed to the housing 2 via the sixth shaft W 6 when the second shift element B 2 is closed, that the sun gear SR 3 of the third planetary gear set RS 3 is connected via the first shaft W 1 as the input shaft of the first transmission shift group 3, and that, as one of the possible blocking variants of the third planetary gear set RS 3, the sun gear SR 3 of the third planetary gear set RS 3 is connected to the ring gear HR 3 of the third planetary gear set RS 3 when the sixth shift element K 4 is locked. The connections of the two planetary gear sets RS 1 and RS 2 in the first transmission shift group 3 have already been described above.FIG. 11 shows a shift pattern for the bottom bracket transmission with the first transmission shift group 3 as a four-speed transmission and with the second transmission shift group 4 as a two-speed transmission. It follows from this that 4 x 2, i.e. eight gears V 1, V 2, V 3, V 4, V 5, V 6, V 7, V 8, can be realized. The shift pattern specifies the shift elements B 1, B 2, K 1, K 2, K 3, K 4 used for the respective gear V 1, V 2, V 3, V 4, V 5, V 6, V 7, V 8. Here, an X in the freewheels K 2, K 3, K 4 as switching elements in the shift pattern means that the freewheels block. This works automatically without external actuation. Furthermore, in the case of a brake B 1, B 2 or a clutch K 1 as a shift element in the shift pattern, an X means that the brake B 1, B 2 or the clutch K 1 is closed. This functions via a suitable actuator system. An empty field in the freewheels K 2, K 3, K 4 means that they do not block. An empty field in the brakes or the clutch B 1, B 2, K 1 means that they are open.In detail, it follows from the shift pattern according to FIG. 11 that, for the realization or shifting of a first gear V 1, the fourth shift element K 2 embodied as a free-wheeling clutch, the fifth shift element K 3 embodied as a free-wheeling clutch and the sixth shift element K 4 embodied as a free-wheeling clutch block, that, for the shifting of a second gear V 2, the first shift element B 1 embodied as a brake is closed and the fifth shift element K 3 embodied as a free-wheeling clutch and the sixth shift element K 4 embodied as a free-wheeling clutch block, that, for the shifting of a third gear V 3, the third shift element K 1 embodied as a clutch is closed and the fourth shift element K 2 embodied as a free-wheeling clutch and the sixth shift element K 4 embodied as a free-wheeling clutch block, that for shifting a fourth gear V4, the first shift element B1 designed as a brake and the third shift element K1 designed as a clutch are closed and the sixth shift element K4 designed as a freewheel blocks, that for shifting a fifth gear V5, the second shift element B2 designed as a brake is closed and the fourth shift element K2 designed as a freewheel and the fifth shift element K3 block, that for shifting a sixth gear V6, the first shift element B1 designed as a brake and the second shift element B2 designed as a brake are closed and the fifth shift element K3 designed as a freewheel blocks, that for shifting a seventh gear V7 the second shifting element B2 designed as a brake and the third shifting element K1 designed as a clutch are closed and the fourth shifting element K2 designed as a freewheel are locked, and / or that for shifting an eighth gear V8 the first shifting element B1, the second shifting element B2 designed as a brake and the third shifting element K1 designed as a clutch are closed.FIG. 12 shows an embodiment of the bottom bracket transmission according to the invention with reference to FIG. 9, in which a torque sensor 5 is connected or connectable to the pedal crankshaft or to the transmission input shaft WAn. For example, a disk-shaped torque sensor 5 can be arranged at the transmission input. However, the torque sensor 5 can also be implemented in a different manner.FIGS. 13 and 14 each show an embodiment of the bottom bracket transmission according to the invention with an additional electric machine EM on the basis of FIG. 12. The electric machine EM can be connected to the pedal crankshaft WAn, as is indicated in FIG. 13. It is also conceivable for the electric machine EM to be linked to the transmission output shaft WAb, as shown in FIG. 14. 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. 15 shows an embodiment of the bottom bracket transmission according to the invention with reference to FIG. 12 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 First transmission shift group 4 Second transmission shift group 5 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 w1 first shaft W2 second shaft W3 third shaft W4 fourth shaft W5 fifth shaft W6 sixth shaft W0 fixed housing connection V1 first gear of the bottom bracket transmission V2 second gear of the bottom bracket transmission V3 third gear of the bottom bracket transmission V4 fourth gear of the bottom bracket transmission V5 fifth gear of the bottom bracket transmission V6 sixth gear of the bottom bracket transmission V7 seventh gear of the bottom bracket transmission V8 eighth gear of the bottom bracket transmission B1 first shifting element B2 second shifting element K1 third shifting element K2 fourth shifting element K3 fourth shifting element K3 fifth shifting element H k4 sixth shift element 1-SR, embodied as a freewheel, first element as sun gear 2-PT second element as planet carrier 2-HR second element as ring gear 3-HR third element as ring gear 3-PT third element as planet carrier 1-SRA first element as first sun gear 2-SRB second element as second sun gear 1-HRA first element as first ring gear 2-HRB first element as second ring gear

Claims

Bottom bracket transmission in planetary construction for a bicycle or a pedelec (1), having a crank shaft (WAn) as drive, having a transmission output shaft (WAb) as output and having further shafts (W1, W2, W3, W4, W5, W6) and having a first transmission shift group (3) and a second transmission shift group (4), wherein the first transmission shift group (3) comprises a first planetary gear set (RS1) and a second planetary gear set (RS2), to which four shift elements (B1, K1, K2, K3) are assigned, wherein the second transmission shift group (4) comprises at least one third planetary gear set (RS3), to which at least two shift elements (B2, K4) are assigned, wherein a first shaft (W1) as input shaft of the first transmission shift group (3) is connected to a second element of the first planetary gear set (RS1), wherein a fifth shaft (W5) as output shaft of the first transmission shift group (3) is connectable via a third shift element (K1) to a third element of the first planetary gear set (RS1) and to a third element of the second planetary gear set (RS2), wherein the third element of the first planetary gear set (RS1) is connected to the third element of the second planetary gear set (RS2), wherein the fifth shaft (W5) is connected via a fifth shift element (K3) to a second element of the second planetary gear set (RS2), wherein, 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) and is connectable to the second element of the second planetary gear set (RS 2) via a fourth shift element (K 2), and wherein a first element of the second planetary gear set (RS 2) is fixed to the housing (2).Bottom bracket transmission according to Claim 1, characterized in that the first transmission shift group (3) is arranged upstream or downstream of the second transmission shift group (4).Bottom bracket transmission according to one of the preceding claims, characterized in that in the second transmission shift group (4) a second element of the third planetary gear set (RS3) is connected to the pedal crankshaft (WAn) or to the fifth shaft (W5) of the first transmission shift group (3), in that a third element of the third planetary gear set (RS3) can be fixed to the housing (2) via a second shift element (B2), and in that a first element of the third planetary gear set (RS3) is connected to the first shaft (W1) of the first transmission shift group (3) or to the transmission output shaft (WAb).Bottom bracket transmission according to one of the preceding claims, characterized in that in the second transmission shift group (4) for blocking the third planetary gear set (RS3), two elements of the third planetary gear set (RS3) can be connected to one another via the sixth shift element (K4).Pedal transmission according to one of the preceding claims, characterized in that the pedal crankshaft (WAn) is connected directly or via the first shaft (W1) to the second element of the first planetary gear set (RS1), in that the transmission output shaft (WAb) is connected to the first element of the third planetary gear set (RS3), in that the first element of the first planetary gear set (RS1) can be fixed to the housing (2) via a second shaft (W2) and via the first shift element (B1) and can be connected to the second element of the second planetary gear set (RS2) via the fourth shift element (K2) and via a fourth shaft (W4), the first element of the second planetary gear set (RS2) is fixed to the housing (2) via a fixed housing connection (W0), the second element of the third planetary gear set (RS3) is connectable to the third element of the first planetary gear set (RS1) via the fifth shaft (W5) and via the third shift element (K1) and via a third shaft (W3) and to the third element of the second planetary gear set (RS2), and also to the second element of the second planetary gear set (RS2) via the fifth shift element (K3) and via the fourth shaft (W4), the third element of the first planetary gear set (RS1) being connected to the third element of the second planetary gear set (RS2) via the third shaft (W3), and in that the third element of the third planetary gear set (RS3) can be fixed to the housing (2) via a sixth shaft (W6) and via the second shift element (B2), and can be connected to the first element of the third planetary gear set (RS3) via the sixth shift element (K4) in order to block the third planetary gear set (RS3).Bottom bracket transmission according to one of Claims 1 to 5, characterized in that the crank shaft (WAn) is connected to the second element of the third planetary gear set (RS3), in that the transmission output shaft (WAb) can be connected directly or via the fifth shaft (W5) and via the third shift element (K1) and via a third shaft (W3) to the third element of the first planetary gear set (RS1) and to the third element of the second planetary gear set (RS2) and via the fifth shift element (K3) and via a fourth shaft (W4) to the second element of the second planetary gear set (RS2), wherein the third element of the first planetary gear set (RS1) is connected via the third shaft (W3) to the third element of the second planetary gear set (RS2), that the first element of the first planetary gear set (RS1) is fixable to the housing (2) via a second shaft (W2) and via the first shift element (B1), and is connectable to the second element of the second planetary gear set (RS2) via the fourth shift element (K2) and via the fourth shaft (W4), that the first element of the second planetary gear set (RS2) is fixed to the housing (2) via a fixed housing connection (W0), the third element of the third planetary gear set (RS3) can be fixed to the housing (2) via a sixth shaft (W6) and via the second shift element (B2), and can be connected to the first element of the third planetary gear set (RS3) via the sixth shift element (K4) for blocking the third planetary gear set (RS3), and the first element of the third planetary gear set (RS3) is connected to the second element of the first planetary gear set (RS1) via the first shaft (W1).Pedal transmission according to one of the preceding claims, characterized in that the first shifting element (B1) and the second shifting element (B2) are each designed as a form-fit brake, in that the third shifting element (K1) is designed as a form-fit clutch, and / or in that the fourth shifting element (K2) and the fifth shifting element (K3) and the sixth shifting element (K4) are each designed as a freewheel.Bottom bracket transmission according to one of the preceding claims, characterized in that the first planetary gear set (RS1) and / or the second planetary gear set (RS2) and / or the third planetary gear set (RS3) is each designed as a minus planetary gear set.Pedal transmission according to Claim 8, characterized in that, in the case of a minus planetary gear set, the first element is designed as a sun wheel (SR1, SR2, SR3), the second element is designed as a planet wheel carrier (PT1, PT2, PT3) and the third element is designed as a ring wheel (HR1, HR2, HR3).Bottom bracket transmission according to one of the preceding claims, characterized in that the first planetary gear set (RS1) and / or the second planetary gear set (RS2) and / or the third planetary gear set (RS3) is each designed as a plus planetary gear set.Pedal transmission according to Claim 10, characterized in that, in the case of a positive planetary gear set, the first element is designed as a sun wheel (SR1, SR2, SR3), the second element is designed as a ring wheel (HR1, HR2, HR3) and the third element is designed as a planet wheel carrier (PT1, PT2, PT3).Pedal transmission according to one of the preceding claims, characterized in that a torque sensor (5) 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 13, characterized in that the electric machine (EM) is arranged axially parallel to the pedal crankshaft (WAn).Bicycle or pedelec (1) with the bottom bracket transmission according to one of the preceding claims.

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