Drive arrangement of a pedelec

Abstract

Drive arrangement of a pedelec with a manual drive shaft (7) and with a first electric drive (EM 1), which are coupled to a common output (15) via a first harmonic gear (WG 1), wherein the output (15) is coupled to a second electric drive (EM 2) via a second harmonic gear (WG 2), characterized in that the first electric drive (EM 1) is arranged coaxially to the manual drive shaft (7) and that the second electric drive (EM 2) is arranged coaxially to an axle fixed to the housing or a fixed axle (8).

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 over, for example, 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 over, for example, 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 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.

[0004] 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.

[0005] 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.

[0006] From the document EP 0 937 600 A2 a transmission for a bicycle is known with two planetary gears, which can also be designed as harmonic gears, each of which is assigned an electric motor to drive the bicycle.

[0007] From the document EP 1 642 820 A1 a hub of a bicycle is known, wherein a gear system with a first planetary gear and a second planetary gear is arranged inside the hub, wherein the sun gears of the planetary gears are connected to rotors of electric motors.

[0008] A differential drive with two motors and two differential shaft gears is known from publication RU 2 162 973 C2. The differential drive allows for an increase in the adjustment range of an output shaft.

[0009] From the publication DE 10 2009 045 447 A1, a bicycle with an electric auxiliary drive with an electric motor and a planetary gear for driving the bicycle both by the electric motor and by muscle power is known.

[0010] From the publication DE 10 2013 206 713 A1, an electric bicycle with an electric drive and a friction gear for continuously changing a gear ratio for driving the electric bicycle is known.

[0011] From the publication DE 10 2016 121 546 A1 a bicycle drive unit with a planetary gear mechanism and two motors for driving is known.

[0012] From the publication JP 2014 - 113 912 A, a bicycle drive with two planetary gears and a motor to drive the bicycle is known.

[0013] From the publication WO 2016 / 034 574 A1, a pedal vehicle with two motors and a planetary gear is known, wherein the first motor is connected to the planetary gear and the second motor is connected to a crank axle of the pedal vehicle.

[0014] 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.

[0015] 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.

[0016] Thus, a drive arrangement is proposed, preferably for a pedelec or the like, which comprises a manual drive, for example, a manual drive shaft embodied as a pedal crankshaft or the like, and a first electric drive. The drives are coupled via a first wave gear to a common output for implementing a superposition function. To avoid a negative riding experience for the rider and to expand the operating options, the output is coupled to a second electric drive via a second wave gear.

[0017] By mechanically connecting at least one second electric drive via at least one second harmonic drive, a fixed ratio is realized in addition to the superimposition function in the drive arrangement according to the invention. Thus, the fixed ratio is provided in parallel with the superimposition function in the drive arrangement. The proposed drive arrangement results in a particularly cost-effective solution, since the components of the existing harmonic drive, including the first electric drive, are reused. The additional fixed ratio is realized by the second electric drive and the second harmonic drive.

[0018] 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.

[0019] 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 first shaft 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 first shaft gear. This essentially creates a reactive electrical power, with the effective drive above the assist speed being provided by the rider's muscle power.

[0020] Within the scope of the present invention, it is provided that the first electric drive is arranged coaxially with the manual drive shaft, and the second electric drive is arranged coaxially with a housing-fixed axle. Thus, the first electric drive with the first wave gear is assigned to the rotating pedal crankshaft, while the second electric drive with the second wave gear is assigned to the fixed axle.

[0021] A particularly space-saving design is achieved with the drive assembly according to the invention because the housing-fixed or stationary axle is arranged axially parallel to the manual drive shaft or the pedal crank shaft. This makes it easy to accommodate the two electric drives with the associated wave gears in a common housing in a space-saving manner.

[0022] In order to couple the second electric drive to the wear part of the pedelec via the second harmonic drive, a preferred embodiment of the invention can provide for an outer bushing of the second harmonic drive to be connected either to the output via an element of the first harmonic drive or virtually directly to the wear part. For example, the outer bushing of the second harmonic drive can be connected to the output via gears, chains, belts, or the like, thereby achieving a larger axial distance between the manual drive shaft and the housing-fixed axle. This allows for a smaller housing overall.

[0023] 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, Fig. 2 a schematic view of a second embodiment of the drive arrangement according to the invention; Fig. 3 a schematic view of a third embodiment of the drive arrangement according to the invention; Fig. 4 a schematic view of a fourth embodiment of the drive arrangement according to the invention and; Fig. 5 a schematic view of a fifth embodiment of the drive arrangement according to the invention.

[0024] In the Fig. 1 to 5 show various embodiments of a drive arrangement according to the invention for a pedelec, comprising a manual drive shaft and a first electric drive EM1 coupled to a common output 15 via a first strain wave gear WG1, wherein the output 15 is coupled to a second electric drive EM2 via a second strain wave gear WG2. The various embodiments differ in the various connection options for the second strain wave gear WG2 to the output 15. The output 15 of the two- or multi-wheel pedelec is connected to the rear or front wheel to be driven, for example, via a sprocket or a belt pulley. It is also possible for the output 15 to be designed as a hub output.

[0025] As already described at the beginning, each wave gear WG 1, WG 2 usually has a mounted wave generator 1, 4 inside, which is provided with an elliptical or longitudinally drawn outer race, which is coupled to a deformable inner bush 2, 5, wherein the respective inner bush 2, 5 has an external toothing, which is in engagement with an outer bush 3, 6 having a circular diameter and having an internal toothing.

[0026] Regardless of the various embodiments, the drive arrangement according to the invention provides that the first electric drive or the first electric machine EM 1 is arranged coaxially with the manual drive shaft or pedal crankshaft 7, wherein the second electric drive or the second electric machine EM 2 is arranged coaxially with a housing-fixed axis 8. The housing-fixed axis 8 is arranged axially parallel to the manual drive shaft 7.

[0027] In this way, a radially nested design of the two electrical machines EM 1, EM 2 and the two strain gears WG 1, WG 2 relative to the pedal crankshaft or the manual drive shaft 7 results, wherein the two electrical drives EM 1, EM 2 and the two strain gears WG 1, WG 2 are arranged in a common housing 14. In the common housing 14, the first electrical drive EM 1 and the first strain gear WG 1 are arranged axially next to one another relative to the manual drive shaft 7, wherein the second electrical drive EM 2 and the second strain gear WG 2 are arranged axially next to one another relative to the axis 8 fixed to the housing.

[0028] The first electric drive EM 1 and the second electric drive EM 2 can be operated both as a motor and as a generator.

[0029] Furthermore, in all embodiments of the drive arrangement, it is provided that the pedal crankshaft with a left pedal 10 at its left end and a right pedal 11 at its right end as a manual drive shaft 7 is connected to a deformable inner bushing 2 of the first wave gear WG 1 and a wave generator 1 of the first wave gear WG 1 is connected to the rotor 12 of the first electric drive EM 1, wherein an outer bushing 3 of the first wave gear WG 1 is connected to the output 15 of the pedelec.

[0030] Furthermore, it is provided that an outer bushing 6 of the second wave gear WG 2 is connected directly or indirectly to the output 15 of the pedelec, wherein an inner bushing 5 of the second wave gear WG 2 is connected to the housing-fixed axle 8 and wherein a wave generator 4 of the second wave gear WG 2 is connected to the rotor 13 of the second electric drive EM 2.

[0031] In the first variant according to Fig. 1, it is provided that the outer bushing 6 of the second harmonic drive WG 2 is connected to the output 15 via the outer bushing 3 of the first harmonic drive WG 1. For this purpose, the outer bushing 3 of the first harmonic drive WG 1 and the outer bushing 6 of the second harmonic drive WG 2 each have external teeth that mesh with each other.

[0032] At the Fig. In the second embodiment of the pedelec drive arrangement according to the invention, shown in Figure 2, the outer bushing 6 of the second strain wave gear WG 2 is coupled to the outer bushing 3 of the first strain wave gear WG 1 via an intermediate gear 9. The intermediate gear 9 is rotatably mounted, with the axle of the intermediate gear 9 being stationary or fixed to the housing and not rotating. This results in the advantage that a larger distance between the pedal crank or the manual drive shaft 7 and the stationary or housing-fixed axle 8 can be realized without increasing the diameter of the outer bushing 3 of the first strain wave gear WG 1 and the second strain wave gear WG 2. This allows for a smaller housing 14 overall.

[0033] In Fig. 3 shows a third embodiment of the invention, in which the outer bushing 6 of the second strain wave gear WG 2 is coupled to the output 15 via a spur gear stage ST. For this purpose, the spur gear stage ST has a first spur gear ST 1 and a second spur gear ST 2, which mesh directly with one another. The first spur gear ST 1 is mounted as a ring gear on the axle 8 fixed to the housing. The second spur gear ST 2 is mounted as a ring gear on the pedal crankshaft or the manual drive shaft 7. The first spur gear ST 1 is connected to the outer bushing 6 of the second strain wave gear WG 2, while the second spur gear ST 2 is connected to the output 15.

[0034] Fig. 4 shows a fourth embodiment of the drive arrangement according to the invention, in which the spur gears ST 1, ST 2 of the spur gear stage ST are coupled to one another via an intermediate gear 17. The intermediate gear 17 is mounted on an axle that is arranged in a stationary manner or fixed to the housing. The use of an intermediate gear 17 results in the advantage that a larger center distance between the pedal crankshaft or the manual drive shaft 7 and the axle 8 fixed to the housing is realized, without the spur gears ST 1, ST 2 extending beyond the diameter of the outer bushing 3 of the first strain wave gear WG 1 and the outer bushing 6 of the second strain wave gear Wege 2, so that a smaller housing 14 can be realized overall.

[0035] Finally, in Fig.5 shows a fifth embodiment of the arrangement according to the invention. In the fifth embodiment, a chain or belt drive 16 is provided as an indirect coupling of the spur gears ST 1, ST 2 of the spur gear stage ST. Accordingly, the belt or chain drive 16 bridges the center distance. This has the advantage that a larger center distance between the pedal crankshaft or the manual drive shaft 7 and the housing-fixed axis 8 can be realized without the spur gears ST 1, ST 2 extending beyond the diameter of the outer bushing 3 of the first strain wave gear WG 1 and the outer bushing 6 of the second strain wave gear WG 2, so that overall a smaller housing 14 can be realized. Reference symbol 1 wave generator of the first wave gear 2 deformable inner bushing of the first wave gear 3 Outer bushing of the first wave gear 4 Shaft generator of the second wave gear 5 deformable inner bushing of the second wave gear 6 Outer bushing of the second wave gear 7 manual drive shaft or pedal crank or pedal crank shaft 8 housing-fixed or fixed axle 9 Intermediate gear 10 left pedal on the crank 11 right pedal on the crank 12 Rotor of the first electric drive or the first electric machine 13 Rotor of the second electric drive or the second electric machine 14 Housing of the drive assembly 15 downforce 16 Chain drive or belt drive 17 Intermediate gear ST spur gear stage ST 1 first spur gear ST 2 second spur gear EM 1 first electric drive or first electric machine EM 2 second electric drive or second electric machine WG 1 first wave gear WG 2 second wave gear

Claims

[1] Drive arrangement of a pedelec with a manual drive shaft (7) and with a first electric drive (EM 1), which are coupled via a first wave gear (WG 1) to a common output (15), wherein the output (15) is coupled via a second wave gear (WG 2) to a second electric drive (EM 2), characterized by that the first electric drive (EM 1) is arranged coaxially to the manual drive shaft (7) and that the second electric drive (EM 2) is arranged coaxially to a housing-fixed axis or a fixed axis (8). [2] Drive arrangement according to claim 1, characterized by that the housing-fixed axis (8) is arranged axially parallel to the manual drive shaft (7). [3] Drive arrangement according to one of the preceding claims, characterized bythat a pedal crankshaft as a manual drive shaft (7) is connected to a deformable inner bushing (2) of the first wave gear (WG 1) and a wave generator (1) of the first wave gear (WG 1) is connected to the rotor (12) of the first electric drive (EM 1), wherein an outer bushing (3) of the first wave gear (WG 1) is connected to the output (15) of the pedelec. [4] Drive arrangement according to one of the preceding claims, characterized by that an outer bushing (6) of the second wave gear (WG 2) is connected directly or indirectly to the output (15) of the pedelec, wherein an inner bushing (5) of the second wave gear (WG 2) is connected to the housing-fixed axle (8), and wherein a wave generator (4) of the second wave gear (WG 2) is connected to the rotor (13) of the second electric drive (EM 2). [5] Drive arrangement according to one of claims 3 or 4, characterized bythat the outer bushing (6) of the second harmonic gear (WG 2) is connected to the output (15) via the outer bushing (3) of the first harmonic gear (WG 1), wherein the outer bushing (3) of the first harmonic gear (WG 1) has an external toothing which engages with an external toothing of the outer bushing (6) of the second harmonic gear (WG 2). [6] Drive arrangement according to one of claims 3 or 4, characterized by that the outer bushing (6) of the second wave gear (WG 2) is coupled to the outer bushing (3) of the first wave gear (WG 1) via an intermediate gear (9). [7] Drive arrangement according to one of claims 3 or 4, characterized by that the outer bush (6) of the second harmonic drive (WG 2) is coupled to the output (15) via a spur gear stage (ST). [8] Drive arrangement according to claim 7, characterized bythat the outer bush (6) of the second harmonic drive (WG 2) is connected to a first spur gear (ST 1) and the output (15) is connected to a second spur gear (ST 2), the two spur gears (ST 1, ST 2) of the spur gear stage (ST) being in engagement with one another. [9] Drive arrangement according to claim 7, characterized by that the spur gears (ST 1, ST 2) of the spur gear stage (ST) are coupled to each other (16) via a chain or belt drive. [10] Drive arrangement according to claim 7, characterized by that the spur gears (ST 1, ST 2) of the spur gear stage (ST) are coupled to one another via an intermediate gear (17). [11] 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 first shaft gear (WG 1) and the second shaft gear (WG 2) are arranged in a common housing (14).

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