Bottom bracket gearshift for an electric bicycle and electric bicycle with such a bottom bracket gearshift

Abstract

Presented herein is a bottom bracket gearshift (1) of an electric bicycle (64) with an auxiliary drive (22), in particular in the form of a central motor. The bottom bracket gearshift (1) has a shift gearbox (4). In order to make the shift gearbox as small and light as possible, an input stage (14) is arranged at the transmission input (10) of the shift gearbox (4). The input stage (14) may be arranged between a bottom bracket shaft (6) and/or the auxiliary drive (22) and is configured as a transmission into high-speed.

Claims

1. A bottom bracket gearshift (1) for an electric bicycle (64) with an auxiliary drive (22), comprising: a bottom bracket shaft (6), a shift gearbox (4) and an input stage (14) arranged at a transmission input (10) of the shift gearbox (4), wherein the input stage (14) is arranged between the shift gearbox (4) and the bottom bracket shaft (6) and is configured as a transmission into high-speed.

2. The bottom bracket gearshift (1) according to claim 1, wherein the input stage (14) comprises an input gear (16) on a driven side on an input shaft (8) of the shift gearbox (4) and an input gear (16) on a drive side coaxial with the bottom bracket shaft (6).

3. The bottom bracket gearshift (1) according to claim 2, wherein the input gear (16) on the drive side is seated on a hollow shaft (30) on an input side, which is mounted on the bottom bracket shaft (6).

4. The bottom bracket gearshift (1) according to any one of claims 1 to 3, wherein a freewheel (20) is arranged between the input stage (14) and the bottom bracket shaft (6).

5. The bottom bracket gearshift (1) according to claim 3, wherein the bottom bracket gearshift (1) comprises an output-side hollow shaft (44), to which a drive gear (48) for a traction device (50) extending to a rear wheel (84) of the electric bicycle (64) is attachable, and wherein the bottom bracket shaft (6) extends coaxially in the output-side hollow shaft (44).

6. The bottom bracket gearshift (1) according to claim 5, wherein at a transmission output of the shift gearbox (4) an output stage (36) comprises a driven-side output gear (40) coaxial with the bottom bracket shaft (6) and an output gear (38) on the drive side on an output shaft (32) of the shift gearbox (4).

7. The bottom bracket gearshift (1) according to claim 6, wherein the driven-side output gear (40) drives the output-side hollow shaft (44).

8. The bottom bracket gearshift (1) according to claim 6, wherein the output stage (36) is configured as a reduction gear.

9. The bottom bracket gearshift (1) according to claim 5, wherein the input-side hollow shaft (30) and the output-side hollow shaft (44) are arranged side by side on the bottom bracket shaft (6).

10. The bottom bracket gearshift (1) according to claim 1, comprising a housing (32) that accommodates the shift gearbox (4) and the bottom bracket shaft (6) and that is configured to accommodate the auxiliary drive (22).

11. The bottom bracket gearshift (1) according to claim 6, wherein the bottom bracket gearshift (1) comprises the auxiliary drive (22) and wherein a power flow from the auxiliary drive (22) and a power flow from the bottom bracket shaft (6) are combined at the input stage (14) or at the output stage (36).

12. The bottom bracket gearshift (1) according to claim 11, wherein the auxiliary drive (22) is structurally integrated into the bottom bracket gearshift (1).

13. An electric bicycle (64) with the bottom bracket gearshift (1) according to claim 1 provided in an area (76) of a bottom bracket of the electric bicycle.

14. The bottom bracket gearshift (1) according to claim 1, wherein the bottom bracket gearshift (1) comprises an output-side hollow shaft (44), to which a drive gear (48) for a traction device (50) extending to a rear wheel (84) of the electric bicycle (64) is attachable, and wherein the bottom bracket shaft (6) extends coaxially in the output-side hollow shaft (44).

15. The bottom bracket gearshift (1) according to claim 1, wherein at a transmission output of the shift gearbox (4) an output stage (36) comprises a driven-side output gear (40) coaxial with the bottom bracket shaft (6) and an output gear (38) on a drive side on an output shaft (32) of the shift gearbox (4).

16. The bottom bracket gearshift (1) according to claim 7, wherein the input-side hollow shaft (30) and the output-side hollow shaft (44) are arranged side by side on the bottom bracket shaft (6).

17. The bottom bracket gearshift (1) according to claim 8, wherein the input-side hollow shaft (30) and the output-side hollow shaft (44) are arranged side by side on the bottom bracket shaft (6).

18. The bottom bracket gearshift (1) according to claim 7, comprising a housing (32) that accommodates the shift gearbox (4) and the bottom bracket shaft (6) and that is configured to accommodate the auxiliary drive (22).

Description

[0048] In the Figures:

[0049] FIG. 1 is a schematic representation of a bottom bracket gearshift of an electric bicycle in a first embodiment;

[0050] FIG. 2 is a schematic representation of a bottom bracket gearshift of an electric bicycle in a further embodiment;

[0051] FIG. 3 is a schematic representation of a bottom bracket shift of an electric bicycle in a further embodiment;

[0052] FIG. 4 is a schematic representation of a bottom bracket gearshift of an electric bicycle in a further embodiment;

[0053] FIG. 5 is a schematic representation of a bottom bracket gearshift of an electric bicycle in a further embodiment;

[0054] FIG. 6 is a schematic representation of an electric bicycle with a bottom bracket gearshift;

[0055] FIG. 7 is a schematic representation of a shift gear of the bottom bracket gearshift;

[0056] FIG. 8 is a schematic representation of the power flow in the shift gearbox of FIG. 7 at different shift stages;

[0057] FIG. 9 is a schematic representation of a bottom bracket gearshift of an electric bicycle in a further embodiment.

[0058] First, the structure of a possible embodiment of a bottom bracket gearshift 1 is explained with reference to FIG. 1. The bottom bracket shift 1 is designed to be mounted in the region of a bottom bracket of a frame of an electric bicycle with a central motor (neither shown in FIG. 1). A power flow through the bottom bracket gearshift 1 is indicated by the double arrow 2.

[0059] The bottom bracket shift 1 has a shift gearbox 4, which is only indicated in FIG. 1. The shift gearbox 4 has an input shaft 8 offset radially and parallel to a bottom bracket shaft 6.

[0060] An input stage 14 is located upstream of a transmission input 10 of the shift gearbox 4. The input stage 14 is a transmission into high speed with a transmission ratio between about 3:1 and about 5:1. It has two meshing input gears 16, 18, in particular in the form of spur-cut gears. One driven-side input gear 18 is seated on an input shaft 8 of the manual shift gearbox 4; the other input gear 16 is seated indirectly or directly on the bottom bracket shaft 6.

[0061] A freewheel 20 is optionally arranged between the input stage 14 and the bottom bracket shaft 6. The freewheel 20 connects the bottom bracket shaft 6 and the input stage 14 in a rotationally rigid manner when the rotational speed of the bottom bracket shaft 6 is at least as great as the rotational speed of the input gear 16 on the drive side. If the rotational speed of the bottom bracket shaft 6 is less than the rotational speed of the input gear 16 on the drive side or is backward, the freewheel 20 automatically disengages and the input gear 16 on the drive side is allowed to rotate independently of the bottom bracket shaft 6.

[0062] The input stage 14, in particular its drive-side input gear 16, is driven not only by the bottom bracket shaft 6, but also by an auxiliary drive 22. For this purpose, the auxiliary drive 22 is preferably directly in engagement with the input stage 14, in particular the input gear 16 on the drive side. The auxiliary drive 22 has an auxiliary motor 24a and optionally a reduction gear 24b. The reduction gear 24b of the auxiliary drive 22 may be designed as a structural unit that may be attached separately from the auxiliary motor 24a of the bottom bracket shift 1, or may be combined or preassembled together with the auxiliary motor 24a to form a structural unit.

[0063] At the input stage 14, in particular the input gear 16 on the drive side, the power flow 2 generated at the bottom bracket shaft 6, which originates from the pedaling movement of a cyclist, and the power flow 2 from the auxiliary drive 22 are combined and directed to the shift gearbox 4. The freewheel 20 prevents power from flowing from the auxiliary drive 22 to the bottom bracket shaft 6; it prevents the auxiliary drive 22 from driving the pedal arms and thus the legs of the cyclist.

[0064] A torque and/or speed sensor 26 may be disposed between the drive-side input gear 16 and the bottom bracket shaft 6, particularly between the freewheel 20 and the drive-side input gear 16, and may output a signal 28 usable for controlling the auxiliary drive 22, the signal being representative of a torque and/or speed applied to the drive-side input gear 16 or the bottom bracket shaft 6. The torque and speed sensor 26 may be located upstream or downstream of the freewheel 20 with respect to the power flow.

[0065] The drive side input gear 16 may be indirectly arranged on the bottom bracket shaft 6, for example by being disposed on a hollow shaft 30, referred to herein as the input-side hollow shaft, which is disposed coaxially with the bottom bracket shaft 6. The hollow shaft 30 may be connected to the bottom bracket shaft 6 via the freewheel 20. The freewheel 20 and the speed and/or torque sensor 28, if present, are preferably arranged on the hollow shaft. The hollow shaft 30 may be rotatably mounted on the bottom bracket shaft 6 and/or in a housing 32 of the bottom bracket shift 1.

[0066] Alternatively, the input gear 16 on the drive side may be mounted directly on the bottom bracket shaft 6 in a rotationally rigid manner. In this case, the freewheel 20 may be located in or on the drive-side input gear 16 so that a hollow shaft is unnecessary.

[0067] An output stage 36 is located at a transmission output 34 of the shift gearbox 4. The output stage 36 has an drive-side output gear 38 and an driven-side output gear 40, which may be configured as a pair of intermeshing spur gears. The output stage 36 is configured as a reduction gear, the reduction ratio being between 1:2 and 1:4.

[0068] The output gear 38 on the drive side is preferably seated on an output shaft 42 of the shift gearbox 4. The output shaft 42 may be radially offset or may be coaxial with the input shaft 8. The input shaft and output shaft of the manual gearbox may be configured to be accessible from the outside on opposite sides of the manual gearbox 4. Alternatively, the input shaft 8 may be a hollow shaft, in which the output shaft 32 is provided, or the output shaft 32 is designed as a hollow shaft, in which the input shaft is provided. The power flow 2 from the shift gearbox 4 is guided via the output shaft 42.

[0069] The driven-side output gear 40 is arranged on an output-side hollow shaft 44 of the bottom bracket gearshift 1, which is arranged coaxially with the bottom bracket shaft 6. The output-side hollow shaft 44 may be mounted on the bottom bracket shaft 6 and/or in the housing 32.

[0070] At the output-side hollow shaft 44, the power flow 2 may be tapped from outside the bottom bracket and used to drive the electric bicycle. For this purpose, the output-side hollow shaft 44 may be configured to carry a drive gear 48, such as a chainring or a toothed belt wheel. A rear wheel (not shown in FIG. 1) of the electric bicycle may then be driven via the drive gear 48 and a traction device 50, such as a chain or a toothed belt.

[0071] The hollow shaft 30 on the input side, if present, and the hollow shaft 44 on the output side are adjacent to each other in the axial direction 52 of the bottom bracket shaft, preferably without overlapping.

[0072] The housing 32 of the bottom bracket gearshift 1 is preferably configured as a structural component of a frame of the electric bicycle. As a structural component, the housing 32 absorbs the forces that occur in the frame during operation. Preferably, the housing 32 stiffens the connection between the seat tube and the down tube and, if applicable, the chain stays.

[0073] The housing 32 surrounds at least the bottom bracket shaft 6, the input gear 16 on the drive side, and the output gear 40 on the driven side. Both the bottom bracket shaft 6 and the hollow shaft 44 on the output side exit the housing 32 so that they are accessible from outside the housing 32. The output side hollow shaft 44 exits the housing 32 on one side 54 only, while the bottom bracket shaft 6 exits on both sides of the housing 32, with the bottom bracket shaft 6 extending farther out of the housing than the output side hollow shaft 44.

[0074] The shift gearbox 4 may have its own housing 56. In this case, the housing 32 of the bottom bracket gearshift 1 and the housing 56 of the shift gearbox 4 are configured to be attached to each other. Preferably, however, the shift gear box 4 is integrated into the housing 32 or arranged therein without its own housing. In this case, the housing 56 may be omitted. The housing 32 then provides bearing points 58, at which the gear shafts of the shift gearbox 4 are mounted.

[0075] The auxiliary drive 22 may be fastened externally or internally to the housing 32. The housing 32 may have corresponding fastening elements, for example flanges, for this purpose. Preferably, however, the auxiliary drive 22, or at least the reduction gear 24b, is also integrated in the housing 32 or arranged inside the housing 32.

[0076] For attachment in the vicinity of the bottom bracket of the electric bicycle, the housing 32 is provided with attachment points 60.

[0077] FIGS. 2 to 4 show bottom bracket gearshifts 1, in which, in contrast to the embodiment of FIG. 1, the gearshift 4 is arranged at least partially between the input stage 14 and the output stage 36 in the direction parallel to the bottom bracket shaft 6. The input shaft 8 and the output shaft 42 are accessible on opposite sides. In terms of function, the bottom bracket gearshifts 1 of FIGS. 1 and 2 are identical. The auxiliary drive 22 is located at a different position in each of the embodiments of FIGS. 2 to 4.

[0078] In the embodiment of FIG. 2, the freewheel 20 is optional. The freewheel 20 may be dispensed with if a control unit 62 of the auxiliary drive 22 is programmed and/or configured in an operationally reliable and, if necessary, redundant manner such that the auxiliary drive may never drive the bottom bracket shaft 6 and thus the legs of the bicycle rider.

[0079] A further freewheel 20a may be arranged between the auxiliary drive 22 and the input stage 16, for example on a drive shaft of the auxiliary drive. The further freewheel 20a rotates freely when the input stage 16 overruns the auxiliary drive 22. This prevents the auxiliary drive 22 from being operated as a generator by the cyclist. The freewheel 20a may also be dispensed with if a control unit 62 of the auxiliary drive 22 is programmed and/or configured in an operationally reliable and, if necessary, redundant manner such that the auxiliary drive cannot go into generator operation by freely spinning up without a load and in this way cannot take away energy from the cyclist.

[0080] As shown in FIG. 2, the auxiliary drive 22 may be spatially disposed, at least section-wise, between the input stage 14 and the housing 32 such that the input stage 14 is spatially disposed between the output stage 36 and the auxiliary drive 22.

[0081] As further exemplified in FIG. 2, the input gear 16 on the drive side may be part of a single-stage reduction gear 24b. A reduction gear designed as a separate component as in the previous embodiment may thus be dispensed with. The auxiliary drive 22 is thus even more structurally integrated into the bottom bracket gearshift 1.

[0082] As FIG. 3 shows, the auxiliary drive 22 may be arranged spatially, at least section-wise, between the input stage 14 and the output stage 36. In such an arrangement, it is advantageous if the torque and/or speed sensor 26 and/or the freewheel 20 are/is also located between the input stage 14 and the output stage 36.

[0083] As shown in FIG. 4 by way of example, the driven-side input gear 18 may be arranged coaxially with the input shaft 8. This makes at least one gear obsolete.

[0084] In the embodiment of FIG. 5, the power flow 2 from the auxiliary drive 22 and the power flow 2 from the bottom bracket shaft 6 are combined at the output stage 36 and not, as in the previous embodiments, at the input stage 14. The freewheel 20 is located between the shift gearbox 4 and the output-side hollow shaft 44, for example, at the output shaft 42 of the shift gearbox 4. The speed and/or torque sensor 26 may be arranged on the bottom bracket shaft 6, as in the embodiment of FIG. 1. In all other respects, the function and structure of the embodiment of FIG. 5 correspond to those of the embodiment of FIG. 1.

[0085] FIG. 6 shows the bottom bracket shift 1 on an electric bicycle 64 that is ready for operation here. The electric bicycle 64 has, for example, a diamond-shaped frame 66 with a down tube 68, a top tube 70 and a seat tube 72. A battery 24c of the auxiliary drive may be disposed on the down tube 68 or other location of the frame 66. The bottom bracket gearshift 1 forms the bottom bracket 74 and is disposed in the region 76 where the down tube 68 and the seat tube 72 are connected. The housing 32 stiffens the frame 66 in the area 76 and is thus a supporting part of the frame 66.

[0086] Attached to the bottom bracket shaft 6 in FIG. 6 are cranks 78 that support pedals 80. On one side 54 of the bottom bracket gearshift 1, spatially between the crank 78 and the housing 32 on the hollow shaft 44 on the output side, a toothed belt pulley is mounted as a drive wheel or drive gear 48. The drive gear 48 drives the rear wheel 84 of the electric bicycle 64 via a toothed belt 82. Of course, a chain drive may be used instead of the toothed belt drive shown.

[0087] A shift element 86 on the handlebar 88 of the electric bicycle 64 is used to actuate the shift gearbox 4.

[0088] With reference to FIG. 7, a shift gearbox 4 is briefly described below in terms of structure and function. In principle, a gearbox 4 other than the one shown may be used instead. However, the shift gearbox 4 should have at least two transmission shafts, namely the input shaft 8 and the output shaft 42, both of which are preferably arranged parallel to and spaced apart from the bottom bracket shaft 6.

[0089] Preferably, the shift gearbox has at least six, more preferably at least nine gears. The shift gearbox 4 may have at least one further gear shaft 90, which is arranged in particular parallel to the input shaft 8.

[0090] Shifting clutches 92 and freewheels 94 may be provided for shifting the individual gears, which may be engaged or disengaged by actuating the shift element 86 (FIG. 5) according to a predetermined pattern. In terms of design and (shift) function, the shift gearbox 4 shown in FIG. 7 corresponds largely to the shift gearbox shown and described in DE 10 2004 045 364 B4, to which full reference is made.

[0091] In contrast to the gearbox of DE 10 2004 045 364 B4, however, the bottom bracket shaft 6 of the bottom bracket gearshift 1 is not simultaneously a gear shaft, but the shift gearbox 4 is offset laterally and parallel to the bottom bracket shaft 6. In the configuration of FIG. 7, the input shaft 8 of the shift gearbox 4 is located in place of the bottom bracket shaft of the shift gearbox of DE 10 2004 045 364 B4. The shift gearbox 4 of FIG. 7 also has at least one more shift stage 96 than the shift gearbox of FIG. 18 of DE 10 2004 045 364 B4, so that a total of nine gears may be shifted using the three shift stages 96a, 96b, 96c.

[0092] The individual clutches are designated below as 92a to 92d and the freewheels as 94a and 94b. The shifting clutch 92a is arranged between the largest gear 100 on the input shaft 8 and the input shaft 8, and the shifting clutch 92b is arranged between the second largest gear on the input shaft 8 and the input shaft 8. The freewheel 94a is disposed between the smallest gear 104 on the input shaft 8 and the input shaft.

[0093] The clutch 92c is disposed between the smallest gear 106 on the output shaft 32 and the output shaft 32, and the clutch 92d is disposed between the second largest gear 108 on the output shaft 32 and the output shaft 32. The freewheel 94b is disposed between the largest gear 110 on the output shaft 32 and the output shaft 32.

[0094] If a clutch 92a to 92d is engaged, the corresponding gear 100-110 is rotationally rigidly connected to the corresponding shaft 8, 32 in the direction of power flow 2, that is, in the direction from the input shaft 8 to the output shaft 42. Opposite to the direction of load transmission, the gear may rotate freely in relation to the shaft. If a clutch 92a to 92d is disengaged, the corresponding gear 100-110 may always rotate freely relative to the corresponding shaft 8, 32.

[0095] The freewheel 94a will spin if the gear 104 rotates at least as fast as the input shaft 8. If the gear 104 attempts to rotate slower than the input shaft 8, the freewheel 94a will connect the gear 104 and the input shaft 8 in a rotationally rigid manner. At this point, there is no slippage of the gear that is dangerous to the cyclist, since the freewheel 94a always transmits the power flow 2 from the transmission input to the transmission output.

[0096] The freewheel 94b slips when the output shaft 32 rotates at least as fast as the gear 110, which is always the case when one of the clutches 92d or 92c is engaged. Otherwise, the output shaft 32 and the gear 110 are rotationally rigidly coupled in the direction of the power flow 2. There is no slippage of the gear at this point, which is dangerous to the cyclist, since the freewheel 94b always transmits the torque.

[0097] A mechanical or electromechanical shift logic, which is not shown, shifts the clutches 92 in a predetermined sequence in order to shift gears with increasing transmission ratios in succession when shifting up and gears with decreasing transmission ratios in succession when shifting down.

[0098] FIG. 8 shows the power flow 2 of the uppermost three shift stages VII, IIX, IX, which may be shifted when the shifting clutch 92a of the largest gear 100 on the input shaft 8 is engaged and the shifting clutch 92b of the second largest gear 102 on the input shaft 8 is disengaged. Via the gear shaft 90, the smallest gear 104 on the input shaft 8 is driven at the highest speed so that the freewheel 94a spins. Consequently, the power flow is via the gear 100 to the further gear shaft 90.

[0099] When the clutch 92c is engaged at the smallest gear 106 of the output shaft 32 and the clutch 92d is disengaged at the second largest gear 108, the power flow 2 is directed from the gear 100 to the gear 104, corresponding to shift stage IX, which provides the largest ratio into the high speed of the shift gearbox 4. The freewheel 94b spins as output shaft 32 rotates faster than the gear 110.

[0100] When the shifting clutch 92c is disengaged and the shifting clutch 92d is engaged, the output shaft 92c still rotates faster than the gear 110 and the freewheel 94b spins. The power flow 2 is from the gear 100 to the gear 108, which corresponds to shift stage IIX.

[0101] Once the clutches 92c and the clutch 92d are disengaged, the output shaft 32 is driven by the freewheel 94b. The power flow 2 is from the gear 100 to the gear 110, corresponding to shift stage VII.

[0102] Shift stages IV to VI (not shown) are shifted accordingly when the shifting clutch 92a is disengaged and the shifting clutch 92b is engaged. The power flow 2 then passes over the gear 102, since the gear 94a rotates faster than the input shaft 8 and the freewheel 94 consequently freewheels. Similarly to shift stages VII to IX, in shift stage IV the clutch 94b is engaged and the clutch 92d is disengaged, in shift stage V the clutch 92c is disengaged and the clutch 92d is engaged; in shift stage IV the clutches 92c and 92d are disengaged and the output shaft 32 is entrained by the freewheel 94b.

[0103] The same applies to shift stages I through III (not shown). The clutches 92a and 92b are disengaged so that the input shaft drives gear 104 through freewheel 94a. In shift stage III, clutch 92c is engaged and clutch 92d is disengaged; in shift stage II, clutch 92c is disengaged and clutch 92d is engaged; in shift stage I, clutches 92c and 92d are disengaged and output shaft 32 is entrained by freewheel 94.

[0104] Another exemplary embodiment of a bottom bracket gearshift 1 is shown in FIG. 9.

[0105] The bottom bracket gearshift 1 has a shift gearbox 4 with six gears and an electric auxiliary drive 22. At least three gear shafts 8, 90, 42 are arranged axially parallel to each other and are indirectly or directly mounted in the housing 32. Accordingly, the bottom bracket gearshift 1 has a total of at least four shafts 6, 8, 42, 90. In this case, the output shaft 42 of the shift gearbox may form the output of the bottom bracket gearshift 1 and be configured to hold the drive gear 50. In contrast to the embodiments described above, there is no hollow shaft 44 on the output side; its function is taken over by the output shaft 42. An output stage 36 is not present. The output shaft 42 extends parallel to the bottom bracket shaft 6.

[0106] The missing output stage may be compensated for by changing the transmission ratio between the drive gear 50 and the pinion or pulley (not shown) on the rear wheel 84 (FIG. 8). By these measures, the bottom bracket gearshift 1 of FIG. 9 is very light.

[0107] The input stage 4 is arranged on the bottom bracket shaft 6. As in the embodiment of FIG. 4, the auxiliary motor 4 drives the input shaft 8 directly, although a freewheel 20a (not shown in FIG. 9) may be provided between the shift gearbox 4 and the auxiliary drive 22. A reduction gear 24b need not be present.

[0108] The housing 32 includes at least two housing parts 32a, 32b that together enclose the auxiliary drive 22, the shift gearbox 4, the input stage 14 and the bottom bracket shaft.

[0109] As in the other embodiments, at least two of the shafts 6, 8, 42, 90 extend out of the housing 32 on at least one side. At least one shaft, here the bottom bracket shaft 6, projects out of the housing 32 on two sides. At least one shaft, here for example the input shaft 8, alternatively another gear shaft 90 or the output shaft 42, is arranged coaxially to the stator and rotor of an electric motor.

[0110] At least three gear shafts, for example the input shaft 8, the output shaft 42 and another gear shaft 90, each have at least two gears on them. At least three gears may be connected to at least one of the shafts 8, 90, 42 in a rotationally fixed manner via clutches 92 and/or freewheels 94.

[0111] One or more of the shafts 8, 90, 42 may also be configured as a hollow shaft and arranged coaxially with one or more shafts from the group comprising the bottom bracket shaft 6, the input shaft 8, at least one further gear shaft 90 and the output shaft 42. On each of the at least four shafts 6, 8, 90, 42 there is provided at least one gear 100-110.

[0112] A speed and/or rotational speed sensor is located on at least one of the shafts 6, 8, 90, 42 or at least one gear 100-110. A torque sensor is located on at least one of the shafts 6, 8, 90, 42 or at least one gear 100-110.

[0113] On at least one of the shafts 6, 8, 90, 42, for example the further gear shaft 90, all gears mounted thereon are completely rotationally fixedly connected to this shaft. At least two shafts from the group comprising the input shaft 8, at least one further gear shaft 90 and the output shaft 42 are located in front of the bottom bracket shaft 6 in the direction of travel when the bottom bracket gearshift 1 is installed in the electric bicycle 64.

REFERENCE SIGNS

[0114] 1 bottom bracket gearshift [0115] 2 power train [0116] 4 shift gearbox [0117] 6 bottom bracket shaft [0118] 8 input shaft [0119] 10 transmission input [0120] 14 input stage [0121] 16 drive-side input gear [0122] 18 driven-side input gear [0123] 20 freewheel [0124] 20a further freewheel [0125] 22 auxiliary drive [0126] 24a auxiliary motor [0127] 24b reduction gear [0128] 24c battery [0129] 26 torque and/or speed sensor [0130] 28 torque and/or speed signal [0131] 30 input hollow shaft [0132] 32 bottom bracket gearshift housing [0133] 32a housing part [0134] 32b housing part [0135] 34 transmission output [0136] 36 output stage [0137] 38 drive-side output gear [0138] 40 driven-side output gear [0139] 42 output shaft of shift gearbox [0140] 44 output-side hollow shaft [0141] 48 input gear [0142] 50 traction device [0143] 52 axial direction [0144] 54 side of housing [0145] 56 shift gearbox housing [0146] 58 bearing points of the gearbox shafts [0147] 60 fastening points of the housing [0148] 62 control unit of the auxiliary drive [0149] 64 electric bicycle [0150] 66 frame [0151] 68 down tube [0152] 70 top tube [0153] 72 seat tube [0154] 74 bottom bracket [0155] 76 area [0156] 78 crank [0157] 80 pedal [0158] 82 toothed belt [0159] 84 rear wheel [0160] 86 shifting element [0161] 88 handlebar [0162] 90 other gear shaft [0163] 92, 92a, 92b, [0164] 92c, 92d shifting clutch [0165] 94, 94a, 94b freewheel of shift gearbox [0166] 96 shift stage [0167] 100, 102, 104, [0168] 106, 108, 110 gear of shift gearbox