Drive arrangement of a pedelec

Abstract

Drive arrangement of a pedelec with a manual drive shaft (9) and with a first electric drive (EM 1), which are coupled to an output (12) via a harmonic gear (WG), characterized in that the output (12) is coupled to a second electric drive (EM 2) via at least one planetary gear set (PS1, PS2).

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 using muscle power and is assisted by an electric auxiliary motor, are well known.

[0003] Furthermore, wave gears are known, which are also referred to as stress wave gears or sliding wedge gears, among other things. The wave gear has a wave generator, an inner bushing and an outer bushing. The outer bushing has internal teeth and the inner bushing has external teeth, which mesh with each other, for example, over two circumferential sections. The cross-section of the outer bushing is circular. The inner bushing is designed to be deformable. The wave generator, which has an elongated or elliptical shape, presses the inner bushing with its external teeth into the internal teeth of the outer bushing, for example, over two circumferential sections. The number of teeth of the external teeth of the inner bushing and the internal teeth of the outer bush are different from one another.For example, if the outer bushing is used as the output element, power can be input to the wave gear drive via both the inner bushing and the wave generator on the drive side. In this way, a superposition function is realized by the wave gear drive.

[0004] EP 0 937 600 A2 relates to a hybrid transmission for a bicycle comprising a mechanism for dividing the energy of a drive source between several differential mechanisms with planetary gears, each connected to its own electric motors, and a mechanism for combining the energies delivered by the differential mechanisms.

[0005] DE 10 2014 106 212 A1 relates to a bottom bracket shell for a bicycle with a receiving space whose width is between 85 mm and 95 mm, and whose height and depth are each between 80 mm and 100 mm.

[0006] WO 2016 / 098 842 A1 relates to a bicycle drive unit having a planetary gear mechanism in which a first motor transmits torque to the planet carrier, a second motor drives and controls the sun gear, and the crankshaft rotation is fed into the planet carrier to enable driving condition-dependent control.

[0007] For example, from the publication DE 10 2015 100 676 B3, a drive assembly for a manually driven vehicle with an electric auxiliary drive is known. The drive assembly has a first drive shaft as a pedal crank with a first pedal and a second pedal as a manual drive. Furthermore, a second drive shaft is provided, which is rotationally fixedly connected to a rotor of the electric auxiliary drive. The pedal crank and the rotor are coupled to an output element via a strain wave gear, wherein the output element is connected to a rear wheel of the vehicle. In the known drive assembly, a wave generator of the strain wave gear is rotationally fixedly connected to the rotor of the auxiliary drive, wherein a preformable inner bushing of the strain wave gear is rotationally fixedly connected to the pedal crank. The output element is connected to an outer bushing of the strain wave gear.

[0008] In such drive-assisted two- or multi-wheeled vehicles, such as pedelecs, the motor must reduce the rider's torque so that the rider feels resistance on the pedal. However, it is known that in pedelec vehicles, for example, motor assistance may only be provided up to a predetermined cut-off speed. If the motor assistance is reduced above a certain cut-off speed, e.g., 25 km / h, this has the disadvantageous consequence of the rider pedaling into the void without resistance. This creates a negative riding experience for the rider. Furthermore, with the known drive assembly, it is not possible for the rider to no longer provide manual propulsion at speeds above the predetermined assistance or cut-off speed.In addition, a mechanical gearshift is required so that the motor support power can be varied when both the riding speed and cadence are specified.

[0009] The present invention is based on the object of proposing a drive arrangement of the type described above, which avoids a negative driving experience and expands the operating possibilities.

[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 embodied as a pedal crankshaft or the like, and a first electric drive. The drives, or the manual drive shaft and the first electric drive, are coupled via a harmonic drive to a common output, for example, to implement a superposition function. To avoid a negative driving experience for the rider and to expand the operating options, the output is coupled to a second electric drive via at least one planetary gear set.

[0012] By mechanically connecting at least a second electric drive via at least one planetary gear set, a pre-transmission ratio, for example, as a fixed ratio, is realized alongside the superposition function in the drive arrangement according to the invention. Thus, the fixed ratio is provided in parallel with the superposition function in the drive arrangement. The proposed drive arrangement results in a particularly cost-effective solution, since the components of the existing strain wave gear, including the first electric drive, are reused. The additional fixed ratio is realized by the second electric drive and the at least single-stage planetary gear.

[0013] The inventive extension with a second electric drive makes it possible to set both a desired assistance level and a desired cadence at any riding speed. Consequently, no conventional mechanical gear adjustment device, such as a derailleur, hub gear, or mechanical hub CVT, is required. The cadence is adjusted by varying the speed of the first electric drive, while the assistance level is adjusted by the freely selectable torque of the second electric drive. It is entirely possible for the second electric drive, designed as an electric machine, to function as a motor or generator.

[0014] It is also possible to offer a higher starting torque, as the second electric drive at the output can apply torque to the output or the sprocket of the pedelec via the second shaft gear, independently of the first electric drive and the strain wave gear. At speeds greater than 25 km / h, for example, the second electric drive can counter-brake accordingly, thus compensating for the motor power of the first electric drive caused by the torque support at the strain wave gear. This essentially creates a reactive electrical power, with the effective drive above the assist speed being provided by the rider's muscle power.

[0015] According to an advantageous development of the present invention, a space-saving arrangement is realized in that the first electric drive is arranged coaxially to the manual drive shaft or to the pedal crankshaft of the pedelec, and in that a rotor of the second electric drive is arranged axially parallel to the manual drive shaft. Furthermore, it can be provided that the at least one planetary gear set is arranged coaxially to the rotor of the second electric drive. Thus, the electric drive with the strain gauge is assigned to the rotating pedal crankshaft, while the planetary gear set is assigned to the rotating rotor of the second electric drive. Consequently, it is readily possible for the drive arrangement according to the invention with the two electric drives as well as with the strain gauge and the at least one planetary gear set to be accommodated in a common housing in a space-saving manner.

[0016] In order to couple the second electric drive to the pedelec's output via the preferably multi-stage planetary gear, several variants are possible with the proposed drive arrangement. For example, the planetary gear or the planetary gear sets can be coupled directly or indirectly to the pedelec's output as a pre-transmission. Within the scope of an indirect coupling, the output of the planetary gear can be coupled to the output, for example, via a spur gear stage, or via additional intermediate gears or the like, or via a belt or chain drive. Depending on the area of ​​application of the drive arrangement according to the invention, a suitable connection can be selected, for example to take into account predetermined installation space requirements.

[0017] 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 according to the invention for a pedelec, and Fig. 2 a schematic view of a second embodiment of the drive arrangement according to the invention for a pedelec.

[0018] In the Fig. 1 and Fig. 2 shows various embodiments of a drive arrangement according to the invention for a pedelec with a manual drive shaft 9 and a first electric drive EM 1, wherein the manual drive shaft 9 and the first electric drive EM 1 are coupled to an output 12 of the pedelec via a strain wave gear WG. Furthermore, it is provided that the output 12 is coupled to a second electric drive EM 2 via at least one planetary gear set PS1, PS2. The various embodiments differ in the different connection options for the planetary gear sets PS1, PS2 to the output 1. As the output 12 of the two- or multi-wheel pedelec, for example, a chain wheel or a belt wheel or the like is connected to the rear or front wheel. It is also possible for the output 12 to be designed as a hub output.

[0019] The proposed wave gear WG typically has a wave generator 1 mounted internally, for example, via ball bearings or the like. The wave generator is provided with an elliptical or longitudinally drawn outer race, which is coupled to a deformable inner bushing 2. The inner bushing 2 has external teeth, each of which meshes with an outer bushing 3 having a circular diameter and internal teeth. In order to effectively support the rider's pedaling power, a wave gear WG with a high gear ratio and a compact design is used.

[0020] Regardless of the embodiment variants, the drive arrangement according to the invention provides that the first electric drive EM 1 is arranged coaxially to the manual drive shaft 9 or pedal crankshaft and that a rotor 10 of the second electric drive EM 2 is arranged axially parallel to the manual drive shaft 9, wherein the at least one planetary gear set PS1, PS2 is arranged coaxially to the rotor 10 of the second electric drive EM 2. This results in a nested design of the two electric drives EM 1, EM 2 as well as the strain wave gear WG and the planetary gear sets PS1, PS2, so that a joint accommodation of the aforementioned components in a housing 16 is easily possible. The first electric drive EM 1 and the second electric drive EM 2 can be operated both as a motor and as a generator.

[0021] Furthermore, it is provided that the pedal crankshaft as a manual drive shaft 9 is connected to the deformable inner bushing 2 of the wave gear WG and the wave generator 1 of the wave gear WG is connected to the rotor 11 of the first electric drive EM1, wherein the outer bushing 3 of the wave gear WG is directly or indirectly connected to the output 12 of the pedelec. In the embodiments shown according to Fig. 1 and Fig. 2, the outer bush 3 is connected to the output 12 via a spur gear stage ST.

[0022] In the exemplary embodiments, the second drive EM 2 is connected directly or indirectly to the output 12 of the pedelec via a first planetary gear set PS1 and a second planetary gear set PS2 as a pre-transmission. The use of a multi-stage planetary gear with the first planetary gear set PS1 and the second planetary gear set PS2 on the axis parallel to the rotor 10 results in improved efficiency. Another particular advantage is that the sun gears SR1, SR2 of the planetary gear sets PS1, PS2 can have a small diameter, since the pedal crankshaft or the manual drive shaft 9 does not run through them. In this way, a large stationary gear ratio of, for example, i0 = -4 can be achieved.

[0023] The first planetary gear set PS1 and the second planetary gear set PS2 are connected in series, with the sun gears SR1, SR2 each forming the input of the planetary gear sets PS1, PS2, and the planetary gear carriers PT1, PT2 each forming the output of the planetary gear sets PS1, PS2. The ring gears HR1, HR2 are each connected to the housing 16. This results in the highest possible gear ratio for the second electric drive EM 2.

[0024] Specifically, the rotor 10 of the second electric drive EM2 is connected to the sun gear SR1 of the first planetary gear set PS1, while the planetary gear carrier PT1 of the first planetary gear set PS1 is connected to the sun gear SR2 of the second planetary gear set PS2. The planetary gear carrier PT2 of the second planetary gear set PS2 is connected to the output 12 of the pedelec at least via a spur gear stage ST.

[0025] At the Fig. In the first embodiment shown in Figure 1, the planetary gear carrier PT2 of the second planetary gear set PS2 is connected to a first spur gear 7 of the spur gear stage ST. The first spur gear 7 can be coupled either directly or indirectly to a second spur gear 8 of the spur gear stage ST. It is also possible for the spur gears 7, 8 to be coupled to one another via a belt or chain drive 13. The second spur gear 8 is preferably arranged on the circumference of the outer bushing 3 of the strain wave gear WG in order to save corresponding length.

[0026] At the Fig.In the second embodiment shown in Figure 2, the first spur gear 7 of the spur gear stage ST is coupled to the second spur gear 8 of the spur gear stage ST via an intermediate gear 4. The intermediate gear 4 is rotatably mounted, with its axis being stationary, i.e., not arranged to rotate. This results in the advantage that a larger axial distance between the pedal crankshaft or the manual drive shaft 9 and the axis of the rotor 10 of the second electric drive EM 2 or the shafts of the sun gears SR1, SR2 of the first planetary gear set PS1 and the second planetary gear set PS2 can be realized without increasing the diameter of the spur gears 7, 8. This results in an overall smaller housing 16. Reference symbol 1 wave generator of the wave gear 2 deformable inner bushing of the strain wave gear 3 Outer bushing of the strain wave gear 4 intermediate gear 7 first spur gear 8 second spur gear 9 manual drive shaft or pedal crank or pedal crank shaft 10 Rotor of the second electric drive or the second electric machine 11 Rotor of the first electric drive or the first electric machine 12 downforce 13 Chain drive or belt drive 14 left pedal on the crank 15 right pedal on the crank 16 Housing of the drive assembly ST spur gear stage EM 1 first electric drive or first electric machine EM 2 second electric drive or second electric machine WG wave gear PS1 first planetary gear set PS2 second 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

Claims

[1] Drive arrangement of a pedelec with a manual drive shaft (9) and with a first electric drive (EM 1), which are coupled to an output (12) via a wave gear (WG), characterized by that the output (12) is coupled to a second electric drive (EM 2) via at least one planetary gear set (PS1, PS2). [2] Drive arrangement according to claim 1, characterized by that the first electric drive (EM1) is arranged coaxially to the manual drive shaft (9), and that a rotor (10) of the second electric drive (EM 2) is arranged axially parallel to the manual drive shaft (9), wherein the at least one planetary gear set (PS1, PS2) is arranged coaxially to the rotor (10) of the second electric drive (EM 2). [3] Drive arrangement according to one of the preceding claims, characterized bythat a pedal crankshaft as a manual drive shaft (9) is connected to a deformable inner bushing (2) of the wave gear (WG) and a wave generator (1) of the wave gear (WG) is connected to the rotor (11) of the first electric drive (EM 1), wherein an outer bushing (3) of the wave gear (WG) is connected directly or indirectly to the output (12) of the pedelec. [4] Drive arrangement according to one of the preceding claims, characterized by that the second electric drive (EM 2) is connected directly or indirectly to the output (2) of the Pedelec via a first planetary gear set (PS1) and a second planetary gear set (PS2) as a pre-transmission. [5] Drive arrangement according to claim 4, characterized bythat the first planetary gear set (PS1) and the second planetary gear set (PS2) are connected in series, wherein the sun gears (SR1, SR2) each form the input of the planetary gear sets (PS1, PS2), the planet gear carriers (PT1, PT2) each form the output of the planetary gear sets (PS1, PS2) and the ring gears (HR1, HR2) are each connected to the housing (16). [6] Drive arrangement according to claim 4 or 5, characterized by that the rotor (10) of the second electric drive (EM 2) is connected to the sun gear (SR1) of the first planetary gear set (PS1), that the planet gear carrier (PT1) of the first planetary gear set (PS1) is connected to the sun gear (SR2) of the second planetary gear set (PS2) and that the planet gear carrier (PT2) of the second planetary gear set (PS2) is connected to the output (12) of the Pedelec via a spur gear stage (ST) and / or via a belt or chain drive (13). [7] Drive arrangement according to claim 6, characterized bythat the spur gears (7, 8) of the spur gear stage (ST) are coupled to one another (13) via a chain or belt drive. [8] Drive arrangement according to claim 6, characterized by that the spur gears (7, 8) of the spur gear stage (ST) are coupled to one another via an intermediate gear (4). [9] Drive arrangement according to claim 6, characterized by that the spur gears (7, 8) of the spur gear stage (ST) are in direct engagement with each other. [10] Drive arrangement according to one of the preceding claims, characterized by that the first electric drive (EM 1) and the second electric drive (EM 2) as well as the shaft gear (WG) and the planetary gear sets (PS1, PS2) are arranged in a common housing (16).

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