Planetary bottom bracket gearbox for a bicycle or e-bike

Abstract

Planetary bottom bracket gearbox for a bicycle or pedelec, with a gearbox input shaft (1) as drive and a gearbox output shaft (2) as driven, with three planetary gear sets (RS1, RS2, RS3), with three freewheel clutches (F1, F2, F3) and with three brakes (B1, B2, B3) to implement eight gears (G1, G2, G3, G4, G5, G6, G7, G8), wherein each planetary gear set (RS1, RS2, RS3) is assigned one brake (B1, B2, B3) and one freewheel clutch (F1, F2, F3), wherein a sun gear (4) of the first planetary gear set (RS1) can be locked via the first brake (B1) and a sun gear (7) of the second planetary gear set (RS2) can be locked via the second brake (B2) and a ring gear (12) of the third planetary gear set (RS3) can be locked via the third The brake (B3) can be locked,wherein a planet carrier (5) of the first planet gear set (RS1) and a planet carrier (8) of the second planet gear set (RS2) as well as a planet carrier (11) of the third planet gear set (RS3) each form the input to the planet gear sets (RS1, RS2, RS3), and wherein a ring gear (6) of the first planet gear set (RS1) and a ring gear (9) of the second planet gear set (RS2) as well as a sun gear (10) of the third planet gear set (RS3) each form the output to the planet gear sets (RS1, RS2, RS3).

Description

[0001] The invention relates to a planetary bottom bracket gear for a bicycle or pedelec. Furthermore, the invention relates to a bicycle or pedelec with the bottom bracket gear.

[0002] A variety of bicycles and pedelecs are known from the state of the art, usually equipped with derailleur or hub gears. Pedelecs differ from bicycles in that they feature an electric motor to assist the rider. In some pedelecs, a hub motor is installed in the front or rear wheel. Hub motors in the front wheel have a negative impact on handling due to their high weight. Hub motors mounted in the rear wheel, on the other hand, have so far been used with derailleur gears that are difficult to maintain and also have a negative impact on handling due to their high weight. For this reason, pedelecs have already been developed in which a countershaft transmission and an electric motor are arranged in a bottom bracket.The disadvantage of the known bottom bracket gears in countershaft design is that they have a low power density and, in addition, due to the fact that only rolling power occurs, a poor efficiency.

[0003] The publications US 2011 / 0 241 306 A1, WO 2013 / 191 572 A1, DE 11 2010 002 286 T5, DE 601 10 585 T2, DE 197 45 419 A1 and WO 2011 / 090 958 A1 disclose bottom bracket and hub gears in planetary design for bicycles.

[0004] The present invention is based on the object of specifying a bottom bracket gear or a bicycle or a pedelec with the bottom bracket gear, which have a high power density and a high efficiency with a high number of gears.

[0005] This object is achieved according to the invention by the features of patent claim 1 and 10, respectively, wherein advantageous and claimed developments result from the subclaims and the description as well as the drawings.

[0006] Accordingly, a planetary bottom bracket gear for a bicycle or pedelec is proposed, comprising a gear input shaft as the input, e.g., a pedal crankshaft or the like, and a gear output shaft as the output. The bottom bracket gear comprises three planetary gear sets, three one-way clutches, and three brakes to realize eight gears, with each planetary gear set being assigned a brake and one-way clutch.Furthermore, in the bottom bracket transmission, a sun gear of the first planetary gear set can be locked via the first brake and a sun gear of the second planetary gear set can be locked via the second brake and a ring gear of the third planetary gear set can be locked via the third brake, wherein a planet gear carrier of the first planetary gear set and a planet gear carrier of the second planetary gear set as well as a planet gear carrier of the third planetary gear set each form the input at the planetary gear sets and wherein a ring gear of the first planetary gear set and a ring gear of the second planetary gear set as well as a sun gear of the third planetary gear set each form the output at the planetary gear sets.

[0007] In this way, a gear set arrangement for the bottom bracket transmission is realized which, due to the interconnection of the gear sets, achieves a particularly high power density with the highest possible efficiency, so that a high level of system integration is achieved, regardless of the axial order in which the gear sets are arranged.

[0008] Furthermore, in the case of planetary gear sets for blocking, the sun gear can be connected to the ring gear or the sun gear to the planet gear carrier or the ring gear to the planet gear carrier via the respective associated overrunning clutch.

[0009] The proposed bottom bracket gear thus comprises three planetary gear sets connected axially in series or coupled, which are locked or gear-geared depending on the gear, so that at least eight gears are shifted via three freewheels and three brakes that are easily accessible from the outside, whereby a particularly high degree of efficiency is achieved in the bottom bracket gear.

[0010] For the mechanical connection of coupled planetary gear sets, the output of one planetary gear set can be connected to the input of the other planetary gear set via an intermediate shaft or the like in the proposed bottom bracket gear.

[0011] Furthermore, shafts or shaft-like elements are used to connect the various gear set elements of the intended planetary gear sets. The term "shaft" does not exclusively refer to a cylindrical, rotatably mounted machine element for transmitting torque, but rather also encompasses general connecting elements that connect the individual gear set elements to one another.

[0012] In order to enable an electrical support power in addition to the manual drive by the rider, the bottom bracket gear according to the invention can be provided with at least one electric machine or the like.

[0013] The electric motor can be connected, for example, to the transmission input shaft, the transmission output shaft, and / or the intermediate shaft, directly or via one or more gear stages, chains, toothed belts, or the like. A shifting element, such as a one-way clutch or the like, can also be used for this purpose. This offers the advantage that, when the electric motor is switched off, no drag torque is generated by an electric motor driven by pedaling. If connected, for example, via a gear stage, a gear reduction can be achieved if necessary.

[0014] Optionally, the bottom bracket transmission can be implemented with a freewheel between the bottom bracket crankshaft and the transmission input. This offers the advantage that a connected electric motor can continue to rotate without the pedals of the bottom bracket crankshaft rotating.

[0015] As already described, the brakes provided can also be designed as switchable freewheels or freewheel brakes, which has the advantage of allowing faster and easier skipping of individual gears when shifting.

[0016] Within the scope of a further development of the invention, it can be provided that the planetary gear sets are equipped, in particular, with a lower or higher absolute stationary gear ratio, for example, with stepped planetary gears. This achieves improved space economy in the bottom bracket gear according to the invention.

[0017] A further aspect of the present invention is to also provide a bicycle or a pedelec or the like with the prescribed bottom bracket gear, whereby the advantages already described and further advantages result.

[0018] The present invention is further explained below with reference to the drawings. They show: Fig. 1 a schematic view of a first embodiment of a bottom bracket gear according to the invention with three planetary gear sets connected axially one behind the other; Fig. 2 a schematic view of a second embodiment of the bottom bracket gear according to the invention with an axially changed sequence of the planetary gear sets; and Fig. 3 a circuit diagram for the first and second design variants of the bottom bracket gear.

[0019] In the Fig. 1 and Fig. 2 shows various embodiments of a bottom bracket gear according to the invention with the respective stationary ratios i0 of the individual gear sets, wherein in the associated switching diagram according to Fig. 3 the possible gears G1 to G8 are given with the corresponding gear ratio i and the gradation or spread φ. The switching diagram shows the individual states of the brakes B1, B2, B3 and the one-way clutches F1, F2, F3, whereby for the brakes B1, B2, B3 a dot indicates the closed state and a cross the open or disengaged state, whilst for the one-way clutches F1, F2, F3 a dot indicates the locking direction state and a line indicates the overrunning drive state. The overrunning mode or overrunning drive state of a freewheel means that the freewheel is not locking. The freewheel can be in overrunning drive if, for example, one of the elements connected to the freewheel is rotating so fast that the freewheel cannot lock. The locking direction state of a freewheel means that the freewheel is locking.

[0020] Regardless of the respective design variant of the bottom bracket gear, the planetary design of the bottom bracket gear is intended to be used for a bicycle, a pedelec, or the like. The bottom bracket gear comprises a transmission input shaft 1 as a drive, which is inserted into the Fig. 1 and Fig. 2 is designed as a pedal crankshaft, and a transmission output shaft 2 as the output, which can be designed, for example, as a chain or toothed belt wheel. The bottom bracket transmission comprises three planetary gear sets RS1, RS2, RS3, whereby a first planetary gear set RS1 and a second planetary gear set RS2 as well as a third planetary gear set RS3 are designed, for example, as a so-called minus planetary gear set. In addition, at least three one-way clutches F1, F2, F3 and three brakes or freewheel brakes B1, B2, B3 are provided, quasi as shifting elements for implementing at least 8 gears G1, G2, G3, G4, G5, G6, G7, G8. Due to the preferred coaxial arrangement of the planetary gear sets RS1, RS2, RS3 of the bottom bracket transmission relative to the pedal crankshaft, installation space advantages arise.

[0021] In all design variants of the bottom bracket gear, it is provided that each planetary gear set RS1, RS2, RS3 is assigned a brake B1, B2, B3 and a freewheel clutch F1, F2, F3, wherein a sun gear 4 of the first planetary gear set RS1 can be fixed to the housing 3 or on the housing side via the first brake B1 and a sun gear 7 of the second planetary gear set RS2 can be fixed via the second brake B2 and a ring gear 12 of the third planetary gear set RS3 can be fixed via the third brake B3.A planet gear carrier 5 of the first planetary gear set RS1 and a planet gear carrier 8 of the second planetary gear set RS2 as well as a planet gear carrier 11 of the third planetary gear set RS3 each form the input at the planetary gear sets RS1, RS2, RS3, wherein a ring gear 6 of the first planetary gear set RS1 and a ring gear 9 of the second planetary gear set RS2 as well as a sun gear 10 of the third planetary gear set RS3 each form the output at the planetary gear sets RS1, RS2, RS3.

[0022] To block the first planetary gear set RS1 via the first one-way clutch F1, the sun gear 4 can be connected to the ring gear 6 or the sun gear 4 can be connected to the planet gear carrier 5 or the ring gear 6 can be connected to the planet gear carrier 5 of the first planetary gear set RS1. Furthermore, to block the second planetary gear set RS2, the sun gear 7 can be connected to the ring gear 9 or the sun gear 7 can be connected to the planet gear carrier 8 or the ring gear 9 can be connected to the planet gear carrier 8 of the second planetary gear set RS2 via the second one-way clutch F2. Finally, to block the third planetary gear set RS3, the sun gear 10 can be connected to the ring gear 12 or the sun gear 10 can be connected to the planet gear carrier 11 or the ring gear 12 can be connected to the planet gear carrier 11 of the third planetary gear set RS3 via the third one-way clutch F3.

[0023] A first version of the bottom bracket gear is in Fig. 1, in which the third planetary gear set RS3 and the second planetary gear set RS2 as well as the first planetary gear set RS1 are provided in axial sequence. Furthermore, the stationary gear ratio i 03 of the third planetary gear set RS3 with -1.62, the stationary gear ratio i 02 of the second planetary gear set RS2 with -1.62, and the stationary gear ratio i 01 of the first planetary gear set RS1 with -3.66 in Fig. 1 is specified.

[0024] In detail, the transmission input shaft 1 is connected to the planetary gear carrier 11 as the input of the third planetary gear set RS3. The sun gear 10, as the output of the third planetary gear set RS3, is connected via an intermediate shaft ZW to the planetary gear carrier 5 as the input of the first planetary gear set RS1, with the ring gear 6, as the output of the first planetary gear set RS1, being connected to the planetary gear carrier 8 as the input of the second planetary gear set RS2.The ring gear 9 as output of the second planetary gear set RS2 is connected to the transmission output shaft 2, wherein the sun gear 4 of the first planetary gear set RS1 is connectable to the ring gear 6 of the first planetary gear set RS1 via the first one-way clutch F1, wherein the ring gear 9 of the second planetary gear set RS2 is connectable to the planet gear carrier 8 of the second planetary gear set RS2 via the second one-way clutch F2, and wherein the planet gear carrier 11 of the third planetary gear set RS3 is connectable to the ring gear 12 of the third planetary gear set RS3 via the third one-way clutch F3.

[0025] A second version of the bottom bracket gear is in Fig. 2, in which the second planetary gear set RS2 and the first planetary gear set RS1 as well as the third planetary gear set RS3 are provided in axial order. Furthermore, the stationary gear ratio i 02 of the second planetary gear set RS2 with -1.62, the stationary gear ratio i 01of the first planetary gear set RS1 with -3.66 and the stationary gear ratio i 03 of the third planetary gear set RS3 with -1.62 in Fig. 2 is specified.

[0026] In detail, it is provided that the transmission input shaft 1 is connected to the planetary gear carrier 5 as the input of the first planetary gear set RS1, that the ring gear 6 as the output of the first planetary gear set RS1 is connected to the planetary gear carrier 8 as the input of the second planetary gear set RS2, that the ring gear 9 as the output of the second planetary gear set RS2 is connected via the intermediate shaft ZW to the planetary gear carrier 11 as the input of the third planetary gear set RS3, that the sun gear 10 as the output of the third planetary gear set RS3 is connected to the transmission output shaft 2, that the sun gear 4 of the first planetary gear set RS1 is connectable via the first overrunning clutch F1 to the ring gear 6 of the first planetary gear set RS1,that the sun gear 7 of the second planetary gear set RS2 is connectable to the ring gear 9 of the second planetary gear set RS2 via the second one-way clutch F2, and that the sun gear 10 of the third planetary gear set RS3 is connectable to the planetary gear carrier 11 of the third planetary gear set RS3 via the third one-way clutch F3. Furthermore, the electric machine EM, which can be operated as a motor or generator, is connected to the intermediate shaft ZW in order to provide assistance to the rider. Accordingly, the second embodiment variant implements, by way of example, a hybridized bottom bracket transmission.The electric machine EM can, for example, be arranged axially parallel to the transmission input shaft 1, preferably in or on the down tube of the bicycle or pedelec. By connecting the electric machine EM to the intermediate shaft ZW, the electric machine EM can be operated in gears G1 to G4 with a gear ratio i=1 and in gears G5 to G8 with a gear ratio i=0.38. When the electric machine EM is connected to the transmission input shaft 1, the electric machine GM can be operated with the respective gear ratio, whereby the electric machine EM can always be operated in the efficiency-optimized range. When the electric machine EM is connected to the transmission output shaft 2, the electric machine EM is operated with the chain ratio, whereby a power shift could be realized.if during a gear change the load would be applied exclusively by the electric machine EM and the transmission is in a load-free state.

[0027] In Fig. 3 is a circuit diagram for the first embodiment according to Fig. 1 and for the second variant according to Fig.2. The shift diagram shows that to shift a first gear G1, the first, second and third brakes B1, B2, B3 are opened or disengaged, with the first, second and third one-way clutches F1, F2, F3 in the blocking direction. To shift a second gear G2, the first brake B1 is closed and the second and third brakes B2, B3 are opened or disengaged, with the first one-way clutch F1 in the overrunning drive state and the second and third one-way clutches F2, F3 in the blocking direction state. To shift a third gear G3, the second brake B2 is closed and the first and third brakes B1, B3 are opened or disengaged, with the second one-way clutch F2 in the overrunning drive state and the first and third one-way clutches F1, F3 in the blocking direction state. To shift a fourth gear G4, the first and second brakes B1, B2 are closed and the third brake B3 is opened orswitched off, with the first and second one-way clutches F1, F2 in the overrunning drive state and the third one-way clutch F3 in the blocking direction state. To shift a fifth gear G5, the third brake B3 is closed and the first and second brakes B1, B2 are opened or switched off, with the first and second one-way clutches F1, F2 in the blocking direction state and the third one-way clutch F3 in the overrunning drive state. To shift a sixth gear G6, the first and third brakes B1, B3 are closed and the second brake B2 is opened or switched off, with the first and third one-way clutches F1, F3 in the overrunning drive state and the second one-way clutch F2 in the blocking direction state. To shift a seventh gear G7, the first brake B1 is opened ordisengaged and the second and third brakes B2, B3 are closed, with the first one-way clutch F1 in the locking direction state and the second and third one-way clutches F2, F3 in the overrunning drive state. To engage an eighth gear G8, the first, second, and third brakes B1, B2, B3 are closed, with the first, second, and third one-way clutches F1, F2, F3 in the overrunning drive state. Reference symbol 1 Gearbox input shaft or crankshaft 2 Gearbox output shaft or output of the bicycle or pedelec 3 housings 4 Sun gear of the first planetary gear set 5 Planetary gear carrier or web of the first planetary gear set 6 Ring gear of the first planetary gear set 7 Sun gear of the second planetary gear set 8 Planet gear carrier of the second planetary gear set 9 Ring gear of the second planetary gear set 10 Sun gear of the third planetary gear set 11 Planet gear carrier of the third planetary gear set 12 Ring gear of the third planetary gear set RS1 first planetary gear set RS2 second planetary gear set RS3 third planetary gear set B1 first brake B2 second brake B3 third brake EM electric machine F1 first freewheel clutch F2 second overrunning clutch F3 third overrunning clutch G1 first course G2 second gear G3 third gear G4 fourth gear G5 fifth gear G6 sixth gear G7 seventh gear G8 eighth gear i 01 Standby ratio of the first planetary gear set i 02 Standby ratio of the second planetary gear set i 03 Standby ratio of the third planetary gear set i Translation φ Grading φ ges Overall classification ZW intermediate shaft

Claims

[1] Bottom bracket gear in planetary design for a bicycle or a pedelec, with a transmission input shaft (1) as input and a transmission output shaft (2) as output, with three planetary gear sets (RS1, RS2, RS3), with three freewheel clutches (F1, F2, F3) and with three brakes (B1, B2, B3) for realizing eight gears (G1, G2, G3, G4, G5, G6, G7, G8), wherein each planetary gear set (RS1, RS2, RS3) is assigned a brake (B1, B2, B3) and a freewheel clutch (F1, F2, F3), wherein a sun gear (4) of the first planetary gear set (RS1) can be locked via the first brake (B1) and a sun gear (7) of the second planetary gear set (RS2) can be locked via the second brake (B2), as well as a ring gear (12) of the third planetary gear set (RS3) can be fixed via the third brake (B3),wherein a planetary gear carrier (5) of the first planetary gear set (RS1) and a planetary gear carrier (8) of the second planetary gear set (RS2) as well as a planetary gear carrier (11) of the third planetary gear set (RS3) each form the input to the planetary gear sets (RS1, RS2, RS3), and wherein a ring gear (6) of the first planetary gear set (RS1) and a ring gear (9) of the second planetary gear set (RS2) as well as a sun gear (10) of the third planetary gear set (RS3) each form the output to the planetary gear sets (RS1, RS2, RS3). [2] Bottom bracket gear according to claim 1, characterized by that in order to block the first planetary gear set (RS1) via the first freewheel clutch (F1) the sun gear (4) can be connected to the ring gear (6) or the sun gear (4) can be connected to the planet gear carrier (5) or the ring gear (6) can be connected to the planet gear carrier (5) of the first planetary gear set (RS1). [3] Bottom bracket gear according to claim 1 or 2, characterized bythat in order to block the second planetary gear set (RS2) via the second freewheel clutch (F2) the sun gear (7) can be connected to the ring gear (9) or the sun gear (7) can be connected to the planet gear carrier (8) or the ring gear (9) can be connected to the planet gear carrier (8) of the second planetary gear set (RS2). [4] Bottom bracket gear according to one of the preceding claims, characterized by that in order to block the third planetary gear set (RS3) via the third freewheel clutch (F3) the sun gear (10) can be connected to the ring gear (12) or the sun gear (10) can be connected to the planet gear carrier (11) or the ring gear (12) can be connected to the planet gear carrier (11) of the third planetary gear set (RS3). [5] Bottom bracket gear according to one of the preceding claims, characterized by that freewheel brakes are provided as brakes (B1, B2, B3, B4). [6] Bottom bracket gear according to one of the preceding claims, characterized bythat the transmission input shaft (1) is connected to the planetary gear carrier (11) as the input of the third planetary gear set (RS3), that the sun gear (10) as the output of the third planetary gear set (RS3) is connected to the planetary gear carrier (5) as the input of the first planetary gear set (RS1), that the ring gear (6) as the output of the first planetary gear set (RS1) is connected to the planetary gear carrier (8) as the input of the second planetary gear set (RS2), that the ring gear (9) as the output of the second planetary gear set (RS2) is connected to the transmission output shaft (2), that the sun gear (4) of the first planetary gear set (RS1) is connectable to the ring gear (6) of the first planetary gear set (RS1) via the first overrunning clutch (F1),that the ring gear (9) of the second planetary gear set (RS2) is connectable to the planet gear carrier (8) of the second planetary gear set (RS2) via the second one-way clutch (F2) and that the planet gear carrier (11) of the third planetary gear set (RS3) is connectable to the ring gear (12) of the third planetary gear set (RS3) via the third one-way clutch (F3). Fig. 1 [7] Bottom bracket gear according to one of claims 1 to 5, characterized bythat the transmission input shaft (1) is connected to the planetary gear carrier (5) as the input of the first planetary gear set (RS1), that the ring gear (6) as the output of the first planetary gear set (RS1) is connected to the planetary gear carrier (8) as the input of the second planetary gear set (RS2), that the ring gear (9) as the output of the second planetary gear set (RS2) is connected to the planetary gear carrier (11) as the input of the third planetary gear set (RS3), that the sun gear (10) as the output of the third planetary gear set (RS3) is connected to the transmission output shaft (2), that the sun gear (4) of the first planetary gear set (RS1) is connectable to the ring gear (6) of the first planetary gear set (RS1) via the first one-way clutch (F1), that the sun gear (7) of the second planetary gear set (RS2) is connected to the ring gear (9) of the second planetary gear set via the second one-way clutch (F2) (RS2) can be connected,and that the sun gear (10) of the third planetary gear set (RS3) is connectable to the planetary gear carrier (11) of the third planetary gear set (RS3) via the third freewheel clutch (F3). Fig. 2 [8] Bottom bracket gear according to one of the preceding claims, characterized bythat for shifting a first gear (G1), the first, second, and third brakes (B1, B2, B3) are opened, with the first, second, and third freewheel clutches (F1, F2, F3) in the locking direction state, or that for shifting a second gear (G2), the first brake (B1) is closed and the second and third brakes (B2, B3) are opened, with the first freewheel clutch (F1) in the overrunning drive state and the second and third freewheel clutches (F2, F3) in the locking direction state, or that for shifting a third gear (G3), the second brake (B2) is closed and the first and third brakes (B1, B3) are opened, with the second freewheel clutch (F2) in the overrunning drive state and the first and third freewheel clutches (F1, F3) in the locking direction state, or that for shifting a fourth gear (G4), the first and second brakes (B1, B2) are closed and the third brake (B3) is opened, the first and second freewheel clutches (F1,F2) are in the overrunning drive state and the third freewheel clutch (F3) is in the blocking direction state, or that for shifting a fifth gear (G5) the third brake (B3) is closed and the first and second brakes (B1, B2) are opened, wherein the first and second freewheel clutches (F1, F2) are in the blocking direction state and the third freewheel clutch (F3) is in the overrunning drive state, or that for shifting a sixth gear (G6) the first and third brakes (B1, B3) are closed and the second brake (B2) is opened, wherein the first and third freewheel clutches (F1, F3) are in the overrunning drive state and the second freewheel clutch (F2) is in the blocking direction state, or that for shifting a seventh gear (G7) the first brake (B1) is opened and the second and third brakes (B2, B3) are closed, wherein the first freewheel clutch (F1) is in the blocking direction state and the second and third Overrunning clutch (F2,F3) are in the overrunning drive state or that for shifting an eighth gear (G8) the first, second and third brakes (B1, B2, B3) are closed, wherein the first, second and third freewheel clutches (F1, F2, F3) are in the overrunning drive state. [9] Bottom bracket gear according to one of the preceding claims, characterized by that at least one electrical machine (EM) is provided. [10] Bicycle or pedelec with a bottom bracket gear according to one of the preceding claims.

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