Drive arrangement of a pedelec

Abstract

Drive arrangement of a pedelec with a manual drive shaft (1) and with an electric drive (EM 1), which are coupled to an output (2) of the pedelec via at least one first planetary gear set (PS1), wherein the electric drive (EM 1) and the at least one first planetary gear set (PS1) are arranged coaxially to the manual drive shaft (1), characterized in that a second planetary gear set (PS2) and a third planetary gear set (PS3) are connected upstream of the first planetary gear set (PS1) as a pre-transmission, wherein the second planetary gear set (PS2) and the third planetary gear set (PS3) are arranged coaxially to the manual drive shaft (1), wherein the rotor (3) of the electric drive (EM 1) is connected to the sun gear (SR2) of the second planetary gear set (PS2),wherein the planetary gear carrier (PT2) of the second planetary gear set (PS2) is connected to the sun gear (SR3) of the third planetary gear set (PS3) and wherein the planetary gear carrier (PT3) of the third planetary gear set (PS3) is connected to the sun gear (SR1) of the first planetary gear set (PS1).

Description

[0001] The present invention relates to a drive arrangement of a pedelec according to the type defined in more detail in the preamble of patent claim 1.

[0002] Manually powered vehicles, especially bicycles or pedelecs, in which a pedalling rider drives the vehicle by muscle power and is assisted by an electric auxiliary motor, are well known.

[0003] For example, DE 10 2013 220 299 A1 discloses a vehicle with an electric auxiliary drive and a continuously variable planetary gear. The vehicle thus comprises a bottom bracket drive with a planetary gear and an electric motor for drive support. However, the design of the planetary gear requires a lot of space. Furthermore, the planetary gear does not allow for a superposition function.

[0004] A bicycle with an electric auxiliary drive is known from the publication DE 10 2009 045 447 A1. The bicycle comprises a crank mechanism with a pedal crankshaft and an electric motor with a rotor. The rotor is connected to a hollow shaft. The hollow shaft is fixedly connected to a sun gear of a planetary gear. A ring gear of the planetary gear is coupled to the output of the bicycle via a chain.

[0005] Another electric bicycle with a motor and a crankshaft as well as a stepped gear transmission is known from the document DE 10 2016 211 000 A1.

[0006] From the publication DE 11 2015 005 678 T5, a drive unit for a bicycle with a planetary gear mechanism, two electric motors, and a crankshaft is known. The planetary gear mechanism is coupled to both the electric motors and the crankshaft, with the output being provided via a chain wheel of the bicycle coupled to the planetary gear mechanism.

[0007] From the document WO 2013 / 160477 A1 a drive train for a bicycle with a first motor and a second motor as well as a planetary gear is known, wherein the second motor is connected to a pedal crankshaft and the first motor is connected to the planetary gear.

[0008] An electric bicycle with a pedal-powered drive train is known from DE 10 2016 208 043 A1. The drive train comprises a pedal crankshaft, an electric motor, and two planetary gear sets, with a first planetary gear set associated with the crankshaft and a second planetary gear set associated with the electric motor.

[0009] The present invention is based on the object of proposing a drive arrangement of the type described above, which has a structurally simple and compact design.

[0010] This object is achieved according to the invention by the features of patent claim 1, wherein advantageous and claimed developments result from the subclaims and the description as well as the drawings.

[0011] Thus, a drive arrangement is proposed, preferably for a pedelec or the like, which has a manual drive, for example, a manual drive shaft designed as a pedal crank or the like, and a preferably electric drive, wherein the manual drive and the electric drive are coupled via at least one first planetary gear set or a planetary gear to an output of the pedelec to implement a superposition function. In order to additionally realize a particularly simple and space-saving design, it is provided that the electric drive and the at least one planetary gear set are arranged coaxially to the manual drive shaft.

[0012] With the drive arrangement according to the invention, the desired superposition function of the two drives is realized by utilizing existing components and the coaxial arrangement, and a robust, compact design is enabled.

[0013] The superposition function allows for speed variability, meaning the cadence can be varied by changing the speed of the electric drive at a given riding speed. Therefore, a conventional mechanical transmission device is not required.

[0014] The gear ratio to the wear member or the rear wheel of the pedelec can be assumed to be constant. When the electric drive is stationary, a gear ratio, e.g. from the pedal crankshaft to the chain wheel or output, can be achieved depending on the connection via the first planetary gear set, for example, from fast or slow. The driving speed at which the boundary between motor and generator operation of the electric drive lies can be set using the final drive ratio or the gear ratio at the output of the pedelec. A short gear ratio is suitable for applications such as mountain bikes, as the electric drive switches over to motor operation at lower driving speeds. A long gear ratio is suitable for applications such as city and trekking bikes, as the electric drive only switches over to motor operation at higher driving speeds.

[0015] In addition, in the drive arrangement according to the invention, advantageously no torque sensor is required, since the torque on the pedal crankshaft can be determined indirectly via the support function of the electric drive on the first planetary gear set.

[0016] Within the scope of the present invention, it is further provided that the electric drive is coupled to the first planetary gear set via a fixed pre-transmission ratio. The connection of the electric drive to the planetary gear set can be established via different elements of the planetary gear set, depending on the transmission requirements.

[0017] For example, a fixed pre-transmission ratio can be provided by a second and a third planetary gear set, which are arranged downstream of the electric drive and upstream of the first planetary gear set. The second planetary gear set and the third planetary gear set are arranged coaxially with the manual drive axis, enabling a particularly compact design. The axial sequence can be varied depending on the application.

[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 drive arrangement of a pedelec according to the invention, and Fig. 2 a schematic view of a second embodiment of the drive arrangement.

[0019] In the Fig. 1 and Fig. 2 are two different embodiments of a drive arrangement according to the invention of a pedelec with a manual drive shaft 1 as a pedal crankshaft with a left pedal 6 at its left end and a right pedal 7 at its right end, as well as with an electric drive EM 1, which is coupled to the output 2 via a first planetary gear set PS1 for implementing the superposition function and preferably via a second planetary gear set PS2 and a third planetary gear set PS3 as a pre-transmission. The output 2 of a two-wheeled or multi-wheeled pedelec can be, for example, a chain wheel or belt wheel, which are connected to the rear or front wheel of the pedelec to be driven. It is also possible for the output 2 to be designed as a hub output.

[0020] The EM 1 electric drive is preferably an electric machine that can operate as both a generator and a motor. However, other drive types can also be used.

[0021] As from Fig. 1 and Fig. 2, the electric drive EM 1 with the first planetary gear set PS1, the second planetary gear set PS2 and the third planetary gear set PS3 is arranged coaxially to the manual drive shaft 1. The three planetary gear sets PS1, PS2, PS3 are arranged axially one behind the other, with the second planetary gear set PS2 and the third planetary gear set PS3 being connected downstream of the electric drive EM 1 as a pre-transmission ratio, while the first planetary gear set PS1 is connected downstream of the second planetary gear set PS2 and the third planetary gear set PS3 to implement the superposition function. Accordingly, the first planetary gear set PS1 is connected, via the two planetary gear sets PS2 and PS3, virtually indirectly to the rotor 3 of the first electric drive EM 1. If no pre-transmission ratio is desired, the first planetary gear set PS1 could also be connected directly to the rotor 3 of the electric drive EM 1.

[0022] In detail, the first version according to Fig. 1, it is provided that the manual drive shaft 1 is connected to a planetary gear carrier PT1 of the first planetary gear set PS1, that a sun gear SR1 of the first planetary gear set PS1 is connected to the rotor 3 of the electric drive EM 1 via the second planetary gear set PS2 and the third planetary gear set PS3, and that a ring gear HR1 of the first planetary gear set PS1 is connected to the output 2 of the Pedelec.

[0023] In the first design variant, when the electric drive EM 1 is stationary, the connection of the first planetary gear set PS1 results in a high-speed transmission from the pedal crank or manual drive shaft 1 to the output shaft 2. At a given travel speed, a specific cadence results, which corresponds to the pedal crankshaft speed. If the actual cadence is higher than the pedal crankshaft speed, the electric drive rotates forward and operates as a generator. If the actual cadence is lower than the pedal crankshaft speed, the electric drive rotates backward and operates as a motor.

[0024] Furthermore, in the first embodiment variant, it is advantageous that the electric drive EM 1 can support a high torque on the manual drive shaft 1, since the torque transmission from sun gear SR1 to the planet gear carrier PT1 or web on the first planetary gear set PS 1 is maximum.

[0025] In detail, the second variant according to Fig. 2, it is provided that the manual drive shaft 1 is connected to the ring gear HR1 of the first planetary gear set PS1, that the sun gear SR1 is connected to the rotor 3 of the electric drive EM1 via the second planetary gear set PS2 and the third planetary gear set PS3, and that the planetary gear carrier PT1 of the first planetary gear set PS1 is connected to the output 2 of the pedelec.

[0026] In the second design variant, when the electric drive EM 1 is stationary, the connection of the first planetary gear set PS1 results in a slow gear ratio from the pedal crank or manual drive shaft 1 to the output 2. At a given travel speed, a certain cadence results, which corresponds to the pedal crankshaft speed. If the actual cadence is higher than the pedal crankshaft speed, the electric drive rotates backwards and works as a generator. This is typically the case at low travel speeds. If the actual cadence is lower than the pedal crankshaft speed, the electric drive rotates forwards and works as a motor. This is typically the case at higher travel speeds.

[0027] The second embodiment variant has the further advantage that due to the connection of the output 2 to the planetary gear carrier PT1, a higher output torque can be generated because the torques of the electric drive EM 1 and the muscle power on the planetary gear carrier PT1 of the first planetary gear set PS1 are added.

[0028] In the case of the planetary gear sets PS2 and PS3 connected in series, regardless of the respective design variants, the sun gears SR2, SR3 each form the input of the planetary gear sets PS2 and PS3, the planet gears PT2, PT3 each form the output of the planetary gear sets PS2 and PS3, and the ring gears HR2, HR3 are each connected to a housing 5. In detail, it is provided that the rotor 3 of the electric drive EM 1 is connected to the sun gear SR2 of the second planetary gear set PS2, that the planet gear carrier PT2 of the second planetary gear set PS2 is connected to the sun gear SR3 of the third planetary gear set PS3, and that the planet gear carrier PT3 of the third planetary gear set PS3 is connected to the sun gear SR1 of the first planetary gear set PS1.

[0029] Due to the interconnection of the planetary gear sets PS2 and PS3, which are designed as pre-transmissions, the highest possible transmission ratio for the electric drive EM 1 can be achieved in both design variants, which means that a compact and cost-effective electric machine with low torque and high speed can be used. Reference symbol 1 manual drive shaft or pedal crank shaft 2 Output of the Pedelec 3 Rotor of the electric drive 4 housings 5 Left pedal on the crankshaft 6 Right pedal on the crankshaft EM 1 electric drive PS1 first planetary gear set PS2 second planetary gear set PS3 third planetary gear set SR1 sun gear of the first planetary gear set PT1 planetary gear carrier of the first planetary gear set HR1 ring gear of the first planetary gear set SR2 sun gear of the second planetary gear set PT2 planetary gear carrier of the second planetary gear set HR2 ring gear of the second planetary gear set SR3 sun gear of the third planetary gear set PT3 planetary gear carrier of the third planetary gear set HR3 ring gear of the third planetary gear set

Claims

[1] Drive arrangement of a pedelec with a manual drive shaft (1) and with an electric drive (EM 1), which are coupled via at least one first planetary gear set (PS1) to an output (2) of the pedelec, wherein the electric drive (EM 1) and the at least one first planetary gear set (PS1) are arranged coaxially to the manual drive shaft (1), characterized bythat a second planetary gear set (PS2) and a third planetary gear set (PS3) are connected upstream of the first planetary gear set (PS1) as a pre-transmission, wherein the second planetary gear set (PS2) and the third planetary gear set (PS3) are arranged coaxially to the manual drive shaft (1), wherein the rotor (3) of the electric drive (EM 1) is connected to the sun gear (SR2) of the second planetary gear set (PS2), wherein the planet gear carrier (PT2) of the second planetary gear set (PS2) is connected to the sun gear (SR3) of the third planetary gear set (PS3) and wherein the planet gear carrier (PT3) of the third planetary gear set (PS3) is connected to the sun gear (SR1) of the first planetary gear set (PS1). [2] Drive arrangement according to claim 1, characterized bythat a pedal crankshaft as a manual drive shaft (1) is connected to a planetary gear carrier (PT1) of the first planetary gear set (PS1), that a sun gear (SR1) is directly or indirectly connected to a rotor (3) of the electric drive (EM 1), and that a ring gear (HR1) of the first planetary gear set (PS1) is connected to the output (2) of the pedelec. [3] Drive arrangement according to claim 1, characterized by that a pedal crankshaft as a manual drive shaft (1) is connected to a ring gear (HR1) of the first planetary gear set (PS1), that a sun gear (SR1) is directly or indirectly connected to a rotor (3) of the electric drive (EM 1), and that a planet gear carrier (PT1) of the first planetary gear set (PS1) is connected to the output (2) of the pedelec. [4] Drive arrangement according to one of the preceding claims, characterized bythat the second planetary gear set (PS2) and the third planetary gear set (PS3) are connected in series, wherein the sun gears (SR2, SR3) each form the input of the planetary gear sets (PS2, PS3), the planet gear carriers (PT2, PT3) each form the output of the planetary gear sets (PS2, PS3) and the ring gears (HR2, HR3) are each connected to a housing (5).

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