Planetary bottom bracket gear for a bicycle or a pedelec as well as bicycle or pedelec

Abstract

A bottom bracket gear in planetary design for a bicycle or pedelec, comprising a pedal crankshaft (1) and at least two planetary gear sets (RS1, RS2, RS3) as well as an electric machine (EM), wherein the planetary gear sets (RS1, RS2, RS3) and the electric machine (EM) are arranged coaxially to the pedal crankshaft (1), wherein a rotor (4) of the electric machine (EM) is connected to a sun gear (8) of a second planetary gear set (RS2) or to a sun gear (11) of a third planetary gear set (RS3), wherein the pedal crankshaft (1) is connected to a sun gear (5) of the first planetary gear set (RS1) or to a ring gear (7) of the first planetary gear set (RS1) or to the ring gear (7) of the first planetary gear set (RS1) and to a ring gear (10) of the second planetary gear set (RS2) or to the ring gear (7) of the first planetary gear set (RS1),is connected to the ring gear (10) of the second planetary gear set (RS2) and to a ring gear (13) of the third planetary gear set (RS3), that an output (2) is connected to a planetary gear carrier (6) of the first planetary gear set (RS1), and that the planetary gear sets (RS1, RS2, RS3) are coupled to one another, characterized in that at least one first planetary gear set (RS1) and one second planetary gear set (RS2) are provided, which are coupled to one another via the sun gear (5) of the first planetary gear set (RS1) and a planetary gear carrier (9) of the second planetary gear set (RS2), and that a third planetary gear set (RS3) is additionally provided, wherein the second planetary gear set (RS2) is connected to a planetary gear carrier (12) of the third planetary gear set (RS3) via a sun gear (8) of the second planetary gear set (RS2).

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 motor-assisted bicycles and pedelecs are known from the state of the art, which are usually equipped with derailleur or hub gears. The motor assistance is usually provided by an electric motor that assists the rider. In some applications, pedelecs or e-bikes have a hub motor installed in the front or rear wheel. Hub motors in the front wheel have a negative impact on handling due to their high weight. In contrast, hub motors installed in the rear wheel 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 the electric drive or electric motor is arranged in the bottom bracket area, parallel to the crankshaft. This parallel arrangement requires a lot of installation space.

[0003] Furthermore, a hybrid drive for an electric bicycle is known from the document DE 10 2009 045 447 A1. The hybrid drive comprises an electric machine arranged coaxially with the pedal crankshaft. Furthermore, a first and second planetary gear set are provided, wherein the pedal crankshaft is fixedly connected to the sun gear of the first planetary gear set and the ring gear of the first planetary gear set is fixedly connected to the output. The planet gear carrier of the first planetary gear set is connected to the planet gear carrier of the second planetary gear set. The electric machine is connected to the planetary gear set in a slow-gear transmission. Such a connection of the electric machine to a master shaft of the first planetary gear set causes disadvantageous, unwanted pedaling for the bicycle user, since the torque of the electric machine must be supported in order to drive the output connected to the ring gear.

[0004] DE 10 2009 014 246 A1 relates to a drive system for a motor-assisted bicycle, comprising a shaft driven by a crank, a motor unit with a rotor and a stator, a planetary gear unit with a sun, at least three planets, a planet carrier and a ring gear, wherein the sun is driven by the motor unit and wherein the ring gear or the planet carrier is connected to the chainring in a rotationally fixed manner.

[0005] DE 10 2016 211 000 A1 relates to an electric bicycle drive train with a stepped planetary gear set, in which the rotor of the motor drives the sun gear, which is connected to a chain ring via a two-stage gear transmission, while at the same time the pedal torque is integrated into the drive via the crankshaft and used to measure the reaction.

[0006] DE 10 2016 225 165 A1 relates to a transmission for a bicycle, comprising a manual transmission that is operatively connected to a bottom bracket crankshaft and has a manual transmission output shaft, as well as an electric motor. The transmission has a superposition gearing arranged downstream of the manual transmission, wherein the electric motor is operatively connected or operatively connectable to one element of the superposition gearing, and the manual transmission output shaft is operatively connected to another element of the superposition gearing.

[0007] DE 10 2017 000 342 A1 relates to a bicycle drive device comprising a first planetary mechanism, two motors and a speed reducer, wherein the first motor acts in a torque-supporting manner on drive, output or crank components and the second motor transmits its rotation to the transmission body of the planetary mechanism via a reduction unit.

[0008] DE 10 2017 219 602 A1 (post-published) relates to a drive arrangement of a pedelec with a manual drive shaft and an electric drive, which is coupled to the output of the pedelec via at least one first planetary gear set, wherein the electric drive and the planetary gear set are arranged coaxially to the manual drive shaft.

[0009] Accordingly, the object of the present invention is to propose a bottom bracket gear and a bicycle or pedelec with the bottom bracket gear, which on the one hand are designed to be space-efficient and on the other hand to be optimized in terms of efficiency and support.

[0010] This object is achieved according to the invention by the subject matter having the features of the independent patent claims, wherein advantageous and claimed developments result from the subclaims and the description as well as the drawings.

[0011] Thus, a planetary bottom bracket gear for a bicycle, pedelec, or similar vehicle is proposed, comprising a pedal crankshaft, at least two planetary gear sets, and an electric motor. The planetary gear sets and the electric motor are arranged coaxially with the pedal crankshaft to save space. To optimize the efficiency and motor assistance of the bottom bracket gear, a rotor of the electric motor is connected to a sun gear of a second planetary gear set, or the rotor is connected to a sun gear of a third planetary gear set.Furthermore, the pedal crankshaft is connected to a sun gear of the first planetary gear set, or the pedal crankshaft is connected to a ring gear of the first planetary gear set, or the pedal crankshaft is connected to the ring gear of the first planetary gear set and to a ring gear of the second planetary gear set, or the pedal crankshaft is connected to the ring gear of the first planetary gear set, to the ring gear of the second planetary gear set, and to a ring gear of the third planetary gear set. Furthermore, an output is connected to a planetary gear carrier of the first planetary gear set, and the planetary gear sets are coupled to one another.

[0012] Thus, a coaxial bottom bracket gear train is proposed, which acts additively on a gear set element of a power-split transmission system using both muscle power and a comparatively small electric motor as a highly efficient electric machine. The power split of the drive is realized by at least two interconnected planetary gear sets, with a so-called negative gear set preferably being used for the planetary gear sets. A negative planetary gear set, as is known, has planetary gears rotatably mounted on its planetary gear carrier, which mesh with a sun gear and a ring gear of this planetary gear set. So that, with the planetary gear carrier held stationary and the sun gear rotating, the ring gear rotates in the opposite direction to the direction of rotation of the sun gear, thus resulting in a negative value for the stationary gear ratio.

[0013] In the bottom bracket gear according to the invention, the output shaft of one of the planetary gear sets forms the output, whereby the output shaft is understood to be the shaft driven by the two driven shafts of the three-shaft gear or the planetary gear set. The fact that both the electric motor and the planetary gear sets are arranged coaxially to the pedal crankshaft results in a particularly small installation space requirement. The planetary gear sets downstream of the electric motor form a slow gear ratio. By using at least two planetary gear sets coupled together, depending on their stationary gear ratio and the type of coupling, a gear ratio of up to 25 or more can be achieved with a comparatively very high efficiency of approximately 97%. Accordingly, with, for example, three planetary gear sets coupled together, a gear ratio of up to 100 or more can be achieved with a comparatively high efficiency of approximately 95.5%.

[0014] A further aspect of the present invention is to also provide a bicycle, pedelec or the like with the above-described bottom bracket gear, whereby the advantages already described and further advantages result.

[0015] The present invention is further explained below with reference to the drawings. They show: Fig. 1 shows a transmission diagram according to a first embodiment of a bottom bracket transmission according to the invention with two planetary gear sets; Fig. 1 A a speed plan of the first embodiment according to Fig. 1; Fig. 2 a transmission diagram according to a second embodiment of the bottom bracket transmission with an alternative interconnection of the two planetary gear sets; Fig. 2 A a speed plan of the second embodiment according to Fig. 2; Fig. 3 a transmission diagram according to a third embodiment of the bottom bracket transmission with three planetary gear sets; Fig. 3 A a speed plan of the third variant according to Fig. 3; Fig. 4 a transmission diagram of a fourth design variant of the bottom bracket transmission with an alternative interconnection of the three planetary gear sets; Fig. 4 A shows a speed diagram of the fourth variant according to Fig. 4; Fig. 5 a gear diagram of a fifth design variant of the bottom bracket gearbox with a further alternative interconnection of the three planetary gear sets; and Fig. 5 A a speed plan of the fifth embodiment according to Fig. 5.

[0016] In the Fig. 1 to 5 show various embodiments of a planetary bottom bracket gear according to the invention for a bicycle or pedelec. For each embodiment, a speed diagram is also shown in the Fig. 1 A to 5 A. A speed diagram is a graphical method with which the speeds and directions of rotation of all gears in a gear train or planetary gear train can be determined. Accordingly, each speed diagram includes the speeds of the various gear set elements So1, So2, So3, St1, St2, St3, Ho1, Ho2, Ho3 of the planetary gear sets RS1, RS2, RS3, as well as the speed n. EM of the electrical machine and the output speed n AB related to a standardized speed n TK the pedal crankshaft 1 can be determined or specified for the respective design variants.

[0017] The proposed bottom bracket transmission, regardless of the respective design variants, features a bottom bracket crankshaft 1 manually driven by the user, at least two planetary gear sets RS1, RS2, RS3, and an electric motor EM. The planetary gear sets RS1, RS2, RS3 and the electric motor EM are arranged coaxially to each other or to the bottom bracket crankshaft 1.

[0018] The first version of the bottom bracket gear according to Fig. 1 comprises a first planetary gear set RS1 and a second planetary gear set RS2, which are coupled to one another via the sun gear 5 of the first planetary gear set RS1 and a planetary gear carrier 9 of the second planetary gear set RS2. Furthermore, a rotor 4 of the electric machine EM is connected to a sun gear 8 of the second planetary gear set RS2, with the pedal crankshaft 1 being connected to a ring gear 7 of the first planetary gear set RS1 and to a ring gear 10 of the second planetary gear set RS2. Furthermore, an output 2, e.g., as a chain or belt wheel, is connected to a planetary gear carrier 6 of the first planetary gear set RS1.

[0019] The Fig. The speed diagram shown in Figure 1 A shows the speed n EMof the electric machine EM, which, due to the coupling, also corresponds to the speed So2 of the sun gear 8 of the second planetary gear set RS2. A graphical connection results between the speed of the electric machine EM and the speed n, which is standardized to 1. TK the pedal crankshaft 1. The speed n TK of the pedal crankshaft 1 also corresponds to the speed Ho1 and Ho2 of the ring gears 7, 10 of the first and second planetary gear sets RS1, RS2, since these are connected to the pedal crankshaft 1. The output speed n AB corresponds to the speed St1 of the planet carrier 6 of the first planetary gear set RS1, since this is connected to the output 2. From the speed diagram, the output speed n AB as well as the speed St2 of the planetary gear carrier 9 of the second planetary gear set RS2 and the speed So1 of the sun gear 5 of the first planetary gear set RS1 can be determined graphically.

[0020] At the Fig. In the second embodiment shown in Figure 2, a first planetary gear set RS1 and a second planetary gear set RS2 are also provided, which are coupled via the sun gear 5 of the first planetary gear set RS1 and the planet gear carrier 9 of the second planetary gear set RS2. However, the second planetary gear set RS2 has a stepped planet, the first stage of which meshes with the ring gear 10 and the second stage of which meshes with the sun gear 8 of the second planetary gear set RS2. Furthermore, the rotor 4 of the electric machine EM is connected to the sun gear 8 of the second planetary gear set RS2, with the pedal crankshaft 1 being connected to the ring gear 7 of the first planetary gear set RS1. The output 2 is connected to the planet gear carrier 6 of the first planetary gear set RS1, and the ring gear 10 of the second planetary gear set RS2 is fixed to the bottom bracket shell 3.

[0021] Thus, in the second embodiment variant, with a stationary gear ratio of, for example, -2 on the first planetary gear set RS1, the torques of the electric machine EM and the bottom bracket crankshaft 1 generated by muscle power can be in a ratio of 1:2, i.e. the torque component of the electric machine EM is half as large after the transmission by the second planetary gear set RS2 compared to the torque generated manually or by muscle power on the bottom bracket crankshaft 1.

[0022] In Fig. 2 A the corresponding speed plan for the second design variant is shown in Fig. 2. The speed n EM of the electric machine EM corresponds to the speed So2 of the sun gear 8 of the second planetary gear set RS2, since they are coupled together. The speed Ho2 of the ring gear 10 of the second planetary gear set RS2 is zero, since this is fixed on the housing side. Through the graphical connection between the speed nEM of the electric machine EM and the speed Ho2 of the ring gear 10 of the second planetary gear set RS2, the speed St2 of the planet carrier 9 of the second planetary gear set RS2 and the speed So1 of the sun gear 5 of the first planetary gear set RS1 are determined, as these are coupled to each other. Based on this speed St2 and So1, the standardized speed n TK the bottom bracket crankshaft 1, the output speed n is graphically calculated AB , which also corresponds to the speed St1 of the planetary gear carrier 6 of the first planetary gear set RS1.

[0023] Fig. 3 shows a third embodiment in which, in addition to the first planetary gear set RS1 and the second planetary gear set RS2, an additional third planetary gear set RS3 is provided, wherein the second planetary gear set RS2 is connected to the planet gear carrier 12 of the third planetary gear set RS3 via the sun gear 8 of the second planetary gear set RS2. Furthermore, the rotor 4 of the electric machine EM is connected to the sun gear 11 of the third planetary gear set RS3, wherein the pedal crankshaft 1 is connected to the ring gear 7 of the first planetary gear set RS1, to the ring gear 10 of the second planetary gear set RS2, and to the ring gear 13 of the third planetary gear set RS3. In addition, the output 2 is connected to the planet gear carrier 6 of the first planetary gear set RS1. The first planetary gear set RS1 and the second planetary gear set RS2 are in turn coupled by the connection of the sun gear 5 of the first planetary gear set RS1 and the planet gear carrier 9 of the second planetary gear set RS2.

[0024] The speed plan according to Fig. 3A of the third variant shows graphically starting from the speed n EM of the electric machine EM up to the speed n TK the pedal crankshaft 1, both the speed St3 of the planetary gear carrier 12 of the third planetary gear set RS3 and the speed So2 of the sun gear 8 of the second planetary gear set RS2 as well as the speed St2 of the planetary gear carrier 9 of the second planetary gear set RS2 and the speed So1 of the sun gear 5 of the first planetary gear set RS1 as well as the output speed n AB , which also corresponds to the speed St1 of the planet carrier 6 of the first planetary gear set RS1. The speed n TK of the bottom bracket crankshaft 1 also corresponds to the speed Ho1, Ho2, Ho3 of the ring gears 7, 10, 13 of the planetary gear sets Rs1, RS2, RS3.

[0025] Fig. Figure 4 shows a fourth embodiment, also with three interconnected planetary gear sets RS1, RS2, RS3, as in the third embodiment, but with a different axial arrangement sequence. In contrast to the third embodiment, only the ring gear 7 of the first planetary gear set RS1 and the ring gear 10 of the second planetary gear set RS2 are connected to the pedal crankshaft 1. Furthermore, the fourth embodiment provides for the ring gear 13 of the third planetary gear set RS3 to be fixed to the bottom bracket shell 3.

[0026] The speed plan according to Fig. 4 A of the fourth embodiment shows a graphical connection between the speed n EMof the electric machine EM and the speed Ho3 of the fixed ring gear 13 of the third planetary gear set 3, the speed St3 of the planet carrier 12 of the third planetary gear set RS3 and the speed So2 of the sun gear 8 of the second planetary gear set RS2. By graphically connecting this speed to the speed n TK the pedal crankshaft 1 graphically shows both the output speed n AB as well as the rotational speed St2 of the planet carrier 9 of the second planetary gear set RS2 and the rotational speed So1 of the sun gear 5 of the first planetary gear set RS1, which are coupled to each other. The rotational speed n EM of the electric machine EM also corresponds to the speed So3 of the sun gear 11 of the third planetary gear set RS3, which is coupled to the electric machine EM. The speed n TK of the pedal crankshaft 1 corresponds to the speeds Ho1 and Ho2, since these ring gears 7, 10 are coupled to the pedal crankshaft 1.

[0027] Fig. 5 shows a fifth embodiment, which also has three interconnected planetary gear sets RS1, RS2, RS3, which have a modified axial arrangement sequence. In the fifth embodiment, it is provided that, in order to couple the first planetary gear set RS1 with the second planetary gear RS2, the ring gear 7 of the first planetary gear set RS1 is connected to the planet gear carrier 9 of the second planetary gear set RS2. In order to couple the second planetary gear set RS2 and the third planetary gear set RS3, the sun gear 8 of the second planetary gear set RS2 is connected to the planet gear carrier 12 of the third planetary gear set RS3. In addition, the ring gear 10 of the second planetary gear set RS2 and the ring gear 13 of the third planetary gear set RS3 are fixed to the bottom bracket shell 3.The rotor 4 of the electric motor EM is connected to the sun gear 11 of the third planetary gear set RS3, while the crankshaft 1 is connected to the sun gear 5 of the first planetary gear set RS1. The output 2 is connected to the planetary gear carrier 6 of the first planetary gear set RS1.

[0028] In the fifth embodiment, with a stationary gear ratio of, for example, -2 on the first planetary gear set RS1, the torques of the electric machine EM and the manually driven pedal crankshaft 1 are in a ratio of 1:2, i.e. the torque component of the electric machine EM is advantageously twice as large after the transmission by the second and third planetary gear sets RS2, RS3 compared to the torque generated by muscle power.

[0029] Fig. Figure 5A shows the speed diagram of the fifth design variant. Starting from the speed n EMof the electric machine EM to the speed Ho3 of the fixed ring gear 13 of the third planetary gear set RS3, the speed St3 of the planet carrier 12 of the third planetary gear set RS3 and the speed So2 of the sun gear 8 of the second planetary gear set RS2 are graphically derived, which are coupled to each other. Again, based on this speed St3, So2 to the speed Ho2 of the fixed ring gear 10 of the second planetary gear set RS2, the speed St2 of the planet carrier 9 of the second planetary gear set RS2 and the speed Ho1 of the ring gear 7 of the first planetary gear set RS1 are graphically derived, which are coupled to each other. Based on the speed St2 and Ho1 to the speed n TK the pedal crankshaft 1 graphically results in the output speed n AB which corresponds to the speed St1 of the planet carrier 6 of the first planetary gear set RS1. Reference symbol 1 crankshaft 2 downforce 3 bottom bracket shell 4 Rotor of the electric machine 5 Sun gear of the first planetary gear set 6 Planet gear carrier of the first planetary gear set 7 Ring gear of the first planetary gear set 8 Sun gear of the second planetary gear set 9 Planet gear carrier of the second planetary gear set 10 Ring gear of the second planetary gear set 11 Sun gear of the third planetary gear set 12 Planet gear carrier of the third planetary gear set 13 Ring gear of the third planetary gear set EM electric machine n speed n AB Output speed n EM Speed ​​of the electric machine n TK Bottom bracket crankshaft speed Ho1 Speed ​​of the ring gear of the first planetary gear set Ho2 Speed ​​of the ring gear of the second planetary gear set Ho3 Speed ​​of the ring gear of the third planetary gear set RS1 first planetary gear set RS2 second planetary gear set RS3 third planetary gear set So1 Speed ​​of the sun gear of the first planetary gear set So2 Speed ​​of the sun gear of the second planetary gear set So3 Speed ​​of the sun gear of the third planetary gear set St1 Speed ​​of the planet carrier of the first planetary gear set St2 Speed ​​of the planet carrier of the second planetary gear set St3 Speed ​​of the planet carrier of the third planetary gear set

Claims

[1] Bottom bracket gear in planetary design for a bicycle or pedelec, with a pedal crankshaft (1) and with at least two planetary gear sets (RS1, RS2, RS3) and with an electric machine (EM), wherein the planetary gear sets (RS1, RS2, RS3) and the electric machine (EM) are arranged coaxially to the pedal crankshaft (1), wherein a rotor (4) of the electric machine (EM) is connected to a sun gear (8) of a second planetary gear set (RS2) or is connected to a sun gear (11) of a third planetary gear set (RS3), that the pedal crankshaft (1) is connected to a sun gear (5) of the first planetary gear set (RS1) or is connected to a ring gear (7) of the first planetary gear set (RS1) or is connected to the ring gear (7) of the first planetary gear set (RS1) and to a ring gear (10) of the second planetary gear set (RS2) or is connected to the ring gear (7) of the first planetary gear set (RS1),is connected to the ring gear (10) of the second planetary gear set (RS2) and to a ring gear (13) of the third planetary gear set (RS3), that an output (2) is connected to a planetary gear carrier (6) of the first planetary gear set (RS1) and that the planetary gear sets (RS1, RS2, RS3) are coupled to one another, , characterized by that at least a first planetary gear set (RS1) and a second planetary gear set (RS2) are provided, which are coupled to one another via the sun gear (5) of the first planetary gear set (RS1) and a planet gear carrier (9) of the second planetary gear set (RS2), and that in addition a third planetary gear set (RS3) is provided, wherein the second planetary gear set (RS2) is connected to a planet gear carrier (12) of the third planetary gear set (RS3) via a sun gear (8) of the second planetary gear set (RS2). [2] Bottom bracket gear according to claim 1, characterized bythat a ring gear (13) of the third planetary gear set (RS3) is fixed to a bottom bracket shell (3). [3] Bottom bracket gear in planetary design for a bicycle or pedelec, with a pedal crankshaft (1) and with at least two planetary gear sets (RS1, RS2, RS3) and with an electric machine (EM), wherein the planetary gear sets (RS1, RS2, RS3) and the electric machine (EM) are arranged coaxially to the pedal crankshaft (1), wherein a rotor (4) of the electric machine (EM) is connected to a sun gear (8) of a second planetary gear set (RS2) or is connected to a sun gear (11) of a third planetary gear set (RS3), that the pedal crankshaft (1) is connected to a sun gear (5) of the first planetary gear set (RS1) or is connected to a ring gear (7) of the first planetary gear set (RS1) or is connected to the ring gear (7) of the first planetary gear set (RS1) and to a ring gear (10) of the second planetary gear set (RS2) or is connected to the ring gear (7) of the first planetary gear set (RS1),is connected to the ring gear (10) of the second planetary gear set (RS2) and to a ring gear (13) of the third planetary gear set (RS3), that an output (2) is connected to a planetary gear carrier (6) of the first planetary gear set (RS1) and that the planetary gear sets (RS1, RS2, RS3) are coupled to one another, , characterized by that a first planetary gear set (RS1), a second planetary gear set (RS2) and a third planetary gear set (RS3) are provided, wherein the ring gear (7) of the first planetary gear set (RS1) is connected to the planet gear carrier (9) of the second planetary gear set (RS2) and wherein the sun gear (8) of the second planetary gear set (RS2) is connected to the planet gear carrier (12) of the third planetary gear set (RS3), that the ring gear (10) of the second planetary gear set (RS2) and the ring gear (13) of the third planetary gear set (RS3) are fixed to the bottom bracket shell (3). [4] Bicycle or pedelec with a bottom bracket gear according to one of the preceding claims.

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