Drive device for an electric bicycle and electric bicycle

Abstract

In at least one embodiment, the drive device (50) for an electric bicycle (100) comprises a transmission (10) with a first drive shaft (1), a second drive shaft (2), and an output element (6). Torque from a first electric motor can be coupled into the transmission via the first drive shaft. Torque from a second electric motor can be coupled into the transmission via the second drive shaft. Torque can be discharged from the transmission via the output element. The first and second drive shafts run parallel to each other, with one drive shaft passing through the other.

Description

[0001] A drive system for an electric bicycle is specified. Furthermore, an electric bicycle is specified.

[0002] Bicycles provide a cost-effective, easy-to-use, and emission-free means of transportation. They have also become popular as sports and fitness equipment, and models have emerged that are particularly suitable for various sporting activities.

[0003] In recent years, enthusiasm for electric bicycles (especially so-called "pedelecs") has been growing, despite the high weight and price of bicycles. With electric bicycles, it's important to provide a reliable, assisted drive system that enables high power transmission.

[0004] The document DE 10 2018 212 584 B3 relates to a bicycle with electric auxiliary drive, comprising an electric motor and a planetary gear.

[0005] The document DE 10 2022 102 011 A1 relates to a drive device for a bicycle with two electric motors, wherein a first electric motor serves directly to propel the vehicle and a second electric motor has two operating modes.

[0006] The document DE 10 2019 201 811 B3 relates to a drive device for an electric bicycle with a first electric motor which drives a first rotor shaft, a second electric motor which drives a second rotor shaft, and a superposition gear having a planetary gear stage.

[0007] The document DE 10 2022 210 892 A1 relates to a drive device for a muscle-powered vehicle with a superposition gear designed as a planetary gear.

[0008] The document DE 10 2019 006 708 A1 concerns a gear drive system with a bottom bracket unit designed as a planetary gear.

[0009] One problem to be solved is to provide a drive device for an electric bicycle that contributes to improved use of the available installation space. Another problem to be solved is to provide an electric bicycle with such a drive device.

[0010] These objects are achieved, inter alia, by the subject matter of patent claims 1 and 15. Advantageous embodiments and further developments are the subject matter of the remaining dependent patent claims and are further apparent from the following description and the figures.

[0011] First, the drive device for an electric bicycle is specified.

[0012] In at least one embodiment, the drive device for an electric bicycle comprises a transmission with a first drive shaft, a second drive shaft, and an output element. Torque from a first electric motor can be coupled into the transmission via the first drive shaft. Torque from a second electric motor can be coupled into the transmission via the second drive shaft. Torque from the transmission can be dissipated via the output element. The first and second drive shafts run parallel to each other. One drive shaft is guided through the other drive shaft.

[0013] By routing one drive shaft through the other, a particularly compact design is achieved. In particular, the drive device thus realizes a compact, parallel superposition drive for an electric bicycle.

[0014] The transmission comprises, in particular, a plurality of intermeshing gears. The transmission converts, for example, a rotation of the first input shaft into a rotation of the output element. Alternatively or additionally, the transmission can convert a rotation of the second input shaft into a rotation of the output element. In particular, the transmission is configured to transmit torque from the first and / or second input shaft to the output element. The transmission is configured, for example, so that the first and second input shafts can rotate independently of one another. For example, the second input shaft can also rotate independently of the output element.

[0015] The output element is, for example, a chainring or a chainring carrier or a chainring spider or a pulley.

[0016] The two drive shafts run parallel to each other. This means that the longitudinal axes of the drive shafts are parallel to each other.

[0017] The drive shafts are either passed through one another or inserted into one another. Either the first drive shaft can pass through the second drive shaft, or the second drive shaft can pass through the first drive shaft. A drive shaft is, in particular, a hollow shaft through which the other drive shaft passes. The first and second drive shafts are, in particular, coaxial with an axis. This axis forms, for example, a rotation axis for both the first and second drive shafts.

[0018] According to at least one embodiment, the torques fed in via the two drive shafts are transmitted within the transmission, at least in sections, on different sides of the drive shafts. "At least in sections" means that the path along which the respective torque is transmitted runs at least partially, i.e., partially or completely, on one side of the output shafts.

[0019] In other words: If the transmission is viewed in a direction perpendicular to the longitudinal axes of the drive shafts, in particular also perpendicular to the axis of rotation of the output element and / or the axis of rotation / longitudinal axis of a pedal shaft of the drive device, wherein the longitudinal axes of the drive shafts are vertically oriented, i.e. run from top to bottom, a torque fed in via the first drive shaft is transmitted at least partially to the right of the longitudinal axes of the drive shafts, and a torque fed in via the second drive shaft is transmitted at least partially to the left of the longitudinal axes of the drive shafts. In order to transmit torque to the different sides of the drive shafts, the transmission comprises at least one gearwheel or at least one gear stage on one side of the drive shafts and at least one gearwheel or at least one gear stage on the other side of the drive shafts.For example, at least one deflection gear stage of the transmission is arranged on one side and at least one further deflection gear stage of the transmission is arranged on the other side of the drive shafts.

[0020] This bilateral or symmetrical torque guidance results in improved space utilization and thus a more compact design.

[0021] In one embodiment, the transmission is designed such that the torque supplied via the first input shaft is diverted from the first input shaft directly to one side of the input shafts, and the torque supplied via the second input shaft is diverted from the second input shaft directly to the opposite side of the input shafts. In particular, the torques from the output shafts are diverted in opposite directions away from the input shafts.

[0022] According to at least one embodiment, the drive device further comprises a first electric motor, which is coupled, in particular directly coupled, to the first drive shaft. During operation of the first electric motor, the first drive shaft is rotated by the first electric motor.

[0023] The drive device is configured, for example, so that the first electric motor can only rotate in one direction, which corresponds to the propulsion of the electric bicycle. In this rotation direction, the first electric motor can be operated, for example, as a motor and generator.

[0024] According to at least one embodiment, the drive device further comprises a second electric motor, which is coupled, in particular directly coupled, to the second drive shaft. During operation of the second electric motor, the second drive shaft is rotated by the second electric motor.

[0025] The drive device is configured, in particular, to enable rotation of the second electric motor in both directions of rotation (if the brake introduced further down is open). The second electric motor can, for example, be operated as a motor only in one of the two directions of rotation. In this one direction of rotation, generator operation of the second electric motor is then preferably also possible. In the other direction of rotation, the second electric motor can then, in particular, only be operated as a generator. Alternatively, it is also possible for the second electric motor to be operated as a motor and generator in both directions of rotation.

[0026] Two elements can be directly or indirectly coupled. "Coupled" here specifically means that the rotation of one element leads to the rotation of the other. Direct coupling here specifically means that there is no translation or reversal of the direction of rotation between the elements. Indirect coupling here specifically means that there is a translation and / or change of direction of rotation between the elements. Indirectly coupled elements are connected to each other via a gear stage, for example. Directly coupled elements can be connected to each other in a rotationally fixed manner.

[0027] The first electric motor, for example, forms a main motor. The second electric motor then forms an auxiliary motor. The main motor has a greater maximum power, in particular a greater maximum torque, than the auxiliary motor. For example, the maximum power or maximum torque of the main motor is at least 1.5 times, at least twice, or at least three times greater than that of the auxiliary motor.

[0028] According to at least one embodiment, the two electric motors are arranged one behind the other in the direction of the longitudinal axes of the first and second drive shafts. For example, the first electric motor is arranged between the transmission and the second electric motor in the direction of the longitudinal axes, or the second electric motor is arranged between the transmission and the first electric motor in this direction.

[0029] According to at least one embodiment, the transmission is configured to transmit torque from an electric motor coupled to the first drive shaft to the output element in order to propel the bicycle with the aid of the motor. That is, the transmission is configured such that the torque acting on the first drive shaft is transmitted to the output element with a specific transmission ratio, thereby enabling the electric bicycle to be propelled by the motor.

[0030] For example, a speed ratio between the first input shaft and the output element is between 1:1 and 1:10 inclusive or between 1:10 and 1:4 inclusive, typically approximately 1:2.

[0031] According to at least one embodiment, the transmission has a pedal shaft, also called a crankshaft. The pedal shaft runs, for example, transversely or perpendicularly to the drive shafts or their longitudinal axes. The rotational axis of the output element also runs, for example, transversely or perpendicularly to the longitudinal axes of the drive shafts. In particular, the rotational axis of the output element and the rotational axis of the pedal shaft are parallel or congruent. The drive device is, for example, an orthogonal drive.

[0032] According to at least one embodiment, the transmission is configured to transmit torque from the pedal shaft to the output element in order to propel the electric bicycle through a pedaling motion. This means that the electric bicycle can be propelled by driving the pedal shaft through a pedaling motion. For this purpose, the pedal shaft is coupled to the output element, in particular, via one or more gear stages of the transmission. The pedal shaft can be coupled to a first of these gear stages via a freewheel or can be rotationally fixedly connected to a gear of this first gear stage.

[0033] According to at least one embodiment, the drive device is a parallel hybrid drive.

[0034] "Hybrid" means that the electric bicycle is propelled forward via the drive system either by muscle power or by a supporting electric motor (here, the first electric motor), or by both. When both work together—i.e., pedaling motion and the supporting electric motor—the torque resulting from the electric motor and the torque resulting from the pedaling motion are added at a junction. The speed resulting from the electric motor at the junction and the speed resulting from the pedaling motion at the junction are the same. The junction could be, for example, the output element or a transmission element connected to it in a rotationally fixed manner. This addition of torque gives rise to the term "parallel."

[0035] In contrast, in a serial hybrid drive, the supporting electric motor is started by the cyclist, i.e. by the pedaling movement, and superimposes its own speed, so that the output then rotates faster (or slower) than the cyclist pedals.

[0036] According to at least one embodiment, the longitudinal axes of the drive shafts intersect or pass through the pedal shaft substantially in or at the center of the pedal shaft. For example, the intersection point or the point of closest approach lies at a distance between 0.4 and 0.6 times, or in the range between 0.45 and 0.55 times, the length of the pedal shaft from a longitudinal end of the pedal shaft.

[0037] If the longitudinal axes of the drive shafts do not cross the pedal shaft but run past it at an angle, the bevel gear stages introduced further down can be designed as hypoid bevel gear stages, for example.

[0038] According to at least one embodiment, the transmission is configured such that a transmission ratio for the torque transmission or the speed transmission from the pedal shaft to the output element can be adjusted by rotating the second drive shaft, for example by means of an electric motor. In particular, the second drive shaft can achieve a continuously variable shifting, i.e., a continuously variable change of the transmission ratio. The second drive shaft therefore does not, or predominantly does not, serve to transmit torque from the second drive shaft to the output element, but rather to adjust the transmission ratio for the torque transmission from the pedal shaft to the output element.

[0039] According to at least one embodiment, the transmission is configured such that rotation of the second drive shaft in one direction of rotation increases the transmission ratio, and rotation in the opposite direction of rotation decreases the transmission ratio. In particular, the transmission is thus constructed such that rotation in both opposite directions of rotation of the second drive shaft is generally possible (for example, when a brake inserted further downstream is released).

[0040] The stationary gear ratio of the transmission, i.e. when the second drive shaft is stationary (not rotating), is determined by the design of the transmission. In this case, this stationary gear ratio preferably does not represent the lowest gear, i.e. the smallest possible gear ratio. Rather, the gear or gear ratio can be increased or decreased (continuously) from the stationary gear ratio by rotating the second drive shaft in one or the other direction of rotation. How high the highest gear ratio or gear of the transmission is and how low the lowest gear ratio or gear of the transmission is depends on the maximum speed at which the second drive shaft can rotate in one or the other direction of rotation. This is determined, for example, by the electric motor coupled to the second drive shaft.

[0041] For example, the (maximum) rotation speed in one direction can be specified by operating the electric motor as a motor. In the other direction, the electric motor's resistance to rotation, and thus the (maximum) rotation speed, can be adjusted by applying a corresponding countervoltage. This could be achieved alternatively or additionally by frequency control, pulse width modulation, or other control techniques. Alternatively, the (maximum) rotation speed in the other direction can also be specified by operating the electric motor as a motor.

[0042] The smallest possible gear ratio (for example, for uphill driving) and the largest possible gear ratio (for example, for high-speed driving) define a speed spread (Δn) of the drive system. The stationary gear ratio, for example, lies in the lower half, especially the lower third, of this speed spread. For example, the stationary gear ratio lies between n1+1 / 4·Δn and n1+2 / 5·Δn, or exactly n1+1 / 3·Δn. Here, n1 is the specified lowest gear ratio of the drive system, n2 is the specified highest gear ratio of the drive system, and Δn = n2-n1 is the speed spread.

[0043] According to at least one embodiment, the transmission has a differential in the form of a bevel gear differential, a planetary gear, a stepped planetary gear, or a crown gear differential for adjusting the gear ratio by means of rotation of the second drive shaft. For this purpose, the differential is coupled in particular to the first and second drive shafts, the pedal shaft, and the output element.

[0044] According to at least one embodiment, the differential is a planetary gear. For example, the second drive shaft is coupled to a ring gear of the planetary gear, for example, indirectly coupled. The pedal shaft is coupled, for example, to a sun gear of the planetary gear, in particular, rotationally fixedly connected or coupled via a freewheel. The output element is coupled, for example, to a planet carrier of the planetary gear, in particular, rotationally fixedly connected. The first drive shaft can be coupled to the planet carrier, in particular, indirectly coupled.

[0045] For example, the axes of rotation of the sun gear, the ring gear, the planet carrier and the planet gears all run parallel to the axis of rotation of the output element or the pedal shaft.

[0046] According to at least one embodiment, the differential is a stepped planetary gear. Then, for example, a sun gear of the stepped planetary gear is coupled to the second input shaft, another sun gear of the stepped planetary gear is coupled to the output element, and the planet carrier of the stepped planetary gear is coupled to the pedal shaft. The planet carrier can be connected to the pedal shaft in a rotationally fixed manner or coupled via a freewheel.

[0047] According to at least one embodiment, the differential is a bevel gear differential. A planetary gear carrier of the bevel gear differential is then coupled, for example, to the pedal shaft, in particular connected in a rotationally fixed manner or coupled thereto via a freewheel. At least one planetary bevel gear is arranged on the planetary gear carrier. The output element is coupled, for example, to a first main bevel gear of the bevel gear differential, in particular connected in a rotationally fixed manner, wherein the first main bevel gear is in engagement with the at least one planetary bevel gear. The second drive shaft can be coupled, in particular indirectly coupled, to a second main bevel gear of the bevel gear differential, wherein the second main bevel gear is in engagement with the at least one planetary bevel gear. For example, the first drive shaft is coupled, in particular indirectly coupled, to the first main bevel gear.

[0048] One, two, or more planetary bevel gears can be arranged on the planetary gear carrier, each meshing with the first and second main bevel gears. The planetary bevel gears of a bevel gear differential can also be referred to as planetary gears. The planetary gear carrier can also be referred to as the planetary gear cage or differential cage.

[0049] The axes of rotation of the two main bevel gears and the planetary gear carrier run, in particular, parallel to the axis of rotation of the output element or the pedal shaft. The axis of rotation of at least one planetary bevel gear runs, in particular, transversely or perpendicularly to the axis of rotation of the output element or the pedal shaft.

[0050] According to at least one embodiment, the first and second main bevel gears are arranged on different sides of the drive shafts. In other words, when viewed perpendicular to the longitudinal axes of the drive shafts, with the longitudinal axes oriented vertically, one main bevel gear is located to the left and one to the right of the drive shafts. This allows for a space-saving and compact design.

[0051] According to at least one embodiment, the transmission has a bevel gear stage, which is coupled on the one hand to the first input shaft and on the other hand to the output element. This bevel gear stage is also referred to below as the first bevel gear stage. A bevel gear of the first bevel gear stage is coupled to the output element for torque transmission in at least one rotational direction, without changing the speed or rotational velocity. This means that the coupling is such that torque can be transmitted from the bevel gear to the output element in at least one rotational direction, with the bevel gear and the output element rotating at the same speed. The axes of rotation of the bevel gear and the output element run parallel or are congruent. In particular, the bevel gear of the first bevel gear stage and the output element are coupled to one another without an intermediate gear stage.A gear stage is defined as a pair of intermeshing gears. For example, the bevel gear of the first bevel gear stage is coupled to the output element (only) via a freewheel or is non-rotatably connected to the output element.

[0052] The other bevel gear of the first bevel gear stage can be connected to the first drive shaft in a rotationally fixed manner. Alternatively, a spur gear stage, also referred to below as the first spur gear stage, can be provided between the first drive shaft and the first bevel gear stage, via which the first drive shaft is then coupled to the first bevel gear stage. For example, a maximum of one gear stage is connected between the first bevel gear stage and the first drive shaft.

[0053] According to at least one embodiment, the transmission has a further bevel gear stage. This further bevel gear stage is also referred to below as the second bevel gear stage. The second bevel gear stage is coupled to the second input shaft. For example, the second input shaft is then connected in a rotationally fixed manner to a bevel gear of the second bevel gear stage. Alternatively, a spur gear stage can be connected between the second input shaft and the second bevel gear stage, via which spur gear stage the second input shaft is coupled to the second bevel gear stage. This spur gear stage is also referred to below as the second spur gear stage. For example, at most one gear stage is connected between the second bevel gear stage and the second input shaft.

[0054] In the case of a planetary differential, the first drive shaft can be coupled to the planet carrier via the first bevel gear stage. In particular, a bevel gear of the first bevel gear stage can be rotationally fixedly coupled to the planet carrier. The second drive shaft is coupled, for example, via the second bevel gear stage to the ring gear of the planetary gear. In particular, the ring gear can be rotationally fixedly connected to a bevel gear of the second bevel gear stage or form this bevel gear.

[0055] In the case of a bevel gear differential, the first drive shaft is coupled to the first main bevel gear, for example, via the first bevel gear stage. The first main bevel gear can be non-rotatably connected to a bevel gear of the first bevel gear stage or form this bevel gear. The second drive shaft is coupled to the second main bevel gear, for example, via the second bevel gear stage. The second main bevel gear can be non-rotatably connected to a bevel gear of the second bevel gear stage or form this bevel gear.

[0056] According to at least one embodiment, the bevel gear stage and the further bevel gear stage are arranged on different sides of the drive shafts. In other words, when viewed perpendicular to the longitudinal axes of the drive shafts, with the longitudinal axes oriented vertically, the bevel gear stage is located to the left of the drive shafts and the further bevel gear stage is located to the right. Accordingly, the first and second spur gear stages can be arranged on different sides of the drive shafts.

[0057] According to at least one embodiment, the differential is a crown gear differential. A planetary gear carrier of the crown gear differential is then coupled, for example, to the pedal shaft, in particular connected in a rotationally fixed manner or coupled thereto via a freewheel. At least one epicyclic spur gear is arranged on the planetary gear carrier. The output element is coupled, for example, to a first main crown gear of the crown gear differential, in particular connected in a rotationally fixed manner, wherein the first main crown gear is in engagement with the at least one epicyclic spur gear. The second drive shaft can be coupled, in particular indirectly coupled, to a second main crown gear of the crown gear differential, wherein the second main crown gear is in engagement with the at least one epicyclic spur gear. For example, the first drive shaft is coupled, in particular indirectly coupled, to the first main crown gear.

[0058] One, two or more planetary spur gears can be arranged on the planetary gear carrier, each of which is in engagement with the first and second main crown gear.

[0059] The rotational axes of the two main crown gears and the planetary gear carrier run, in particular, parallel to the rotational axis of the output element or the pedal shaft. The rotational axis of the at least one planetary spur gear runs, in particular, transversely or perpendicularly to the rotational axis of the output element or the pedal shaft.

[0060] According to at least one embodiment, the first and second main crown gears are arranged on different sides of the drive shafts. In other words, when viewed perpendicular to the longitudinal axes of the drive shafts, with the longitudinal axes oriented vertically, one main crown gear is located to the left and one to the right of the drive shafts. This allows for a space-saving and compact design.

[0061] According to at least one embodiment, the drive device comprises a brake. The brake is assigned to the second drive shaft. The brake is coupled, in particular, to the second drive shaft. The brake is configured to counteract rotation of the second drive shaft in at least one rotational direction, for example, to lock or block this rotation.

[0062] The brake can act directly on the second drive shaft or on an electric motor coupled to the second drive shaft. The brake can be configured to counteract the rotation of the second drive shaft in only one direction or in both directions. "Rotation" here, of course, refers to rotation around the longitudinal axis of the second drive shaft.

[0063] The brake can be configured to completely block or prevent rotation in at least one direction of rotation. Alternatively or additionally, the brake can be configured so that the braking force exerted by it is adjustable. Depending on the set braking force, the brake can impede rotation of the second drive shaft in at least one direction of rotation to varying degrees, optionally even completely blocking it. Complete blocking can be achieved, for example, through a positive engagement. Making rotation more difficult or even completely blocked, i.e. adjusting the braking force, can be achieved, for example, through frictional engagement.

[0064] The brake can be controlled mechanically and / or electrically. For example, the braking effect of the brake can be adjusted using electrical control signals. However, it is also possible for the braking effect of the brake to be manually adjustable by the operator of the electric bicycle. For example, the brake of the drive device can be coupled or connectable to the rear wheel and / or front wheel brake of the electric bicycle, so that when the front wheel or rear wheel brake is applied, the brake for the second drive shaft is also applied and then counteracts rotation of the second drive shaft in at least one direction of rotation.

[0065] According to at least one embodiment, the brake is designed to apply a supporting torque against rotation of the second drive shaft when the electric bicycle starts moving from a standstill, in particular when the standstill gear ratio is set, in order to enable stiff starting. In particular, the brake is designed to counteract the torque transmitted from the pedal shaft to the second drive shaft when starting with a correspondingly large supporting torque. In this way, it can be avoided that work applied for manual propulsion is lost in rotation of the second drive shaft or in rotation of the (second) electric motor connected to it. In particular, the brake blocks rotation of the second drive shaft in both directions of rotation when starting from a standstill.

[0066] According to at least one embodiment, the brake is a mechanical brake. For example, the brake comprises brake blocks for clamping a brake disc. The brake disc is arranged, for example, in a rotationally fixed manner on the rotor of the second electric motor or on the second drive shaft itself. Alternatively, the brake can also have one or more pins that engage in recesses when the brake is applied to completely block rotation of the second drive shaft. For example, the brake comprises a freewheel for blocking rotation of the second drive shaft only in one direction of rotation.

[0067] According to at least one embodiment, the brake is configured to generate a braking effect for both directions of rotation of the second drive shaft through frictional engagement. This means that when the brake is applied, it counteracts rotation of the second drive shaft in both directions of rotation through frictional engagement.

[0068] According to at least one embodiment, the brake is configured to decelerate an existing rotation of the second drive shaft. For example, the brake is configured to decelerate or counteract a rotation of the second drive shaft that sets a lower gear than the stationary gear ratio. Alternatively or additionally, the brake can be configured to decelerate or counteract a rotation of the second drive shaft that sets a higher gear than the stationary gear ratio.

[0069] According to at least one embodiment, the brake can be used to adjust the braking force with which rotation of the second drive shaft is tightly counteracted. In particular, the friction force with which the brake achieves its braking effect can be increased or decreased.

[0070] Furthermore, it is also possible that the brake is an electromagnetic brake, for example a magnetic brake or eddy current brake

[0071] Next, the electric bike is specified. The electric bike is specifically a pedelec.

[0072] In at least one embodiment, the electric bicycle comprises a drive device according to one of the embodiments described here. Furthermore, the electric bicycle comprises a down tube. The two drive shafts extend substantially parallel to the main extension direction of the down tube. For example, the drive shafts are arranged within the down tube. The first and second electric motors can also be arranged in the down tube. The down tube extends, in particular, perpendicular to the pedal shaft.

[0073] Since the electric bicycle has a drive device described here, all features disclosed in connection with the drive device are also disclosed for the electric bicycle and vice versa.

[0074] A drive device described herein and an electric bicycle described herein are explained in more detail below with reference to drawings using exemplary embodiments. The same reference numerals indicate the same elements in the individual figures. To the extent that elements or components in the various figures have the same function, their description will not be repeated for each of the following figures. For reasons of clarity, elements may not be provided with corresponding reference numerals in all figures.

[0075] They show: Fig. 1 an embodiment of an electric bicycle, Fig. 2 to 7 different embodiments of a drive device.

[0076] Fig. Figure 1 schematically shows an electric bicycle 100 with a bicycle frame 70, which includes, among other things, a lower frame section 60 forming a down tube. The frame section 60 extends toward a bottom bracket, which includes a pedal spindle 5. The pedal shaft 5 is part of a drive device 50 for the electric bicycle 100.

[0077] The following Fig. 2 to 6 show embodiments of this drive device 50. Bearings for relative rotation between the adjacent elements are shown as black rectangles.

[0078] Figures 2 and 3 show an embodiment of the drive device 50 in two different representations. The drive device 50 comprises a transmission 10 with two drive shafts 1, 2 and an output element 6. Torque is coupled into the transmission 10 via the drive shafts 1, 2. Torque can be dissipated from the transmission 10 via the output element 6.

[0079] In this case, the first drive shaft 1 is a hollow shaft, and the second drive shaft 2 is guided or inserted through the hollow shaft 1 and arranged coaxially with it. In particular, the longitudinal axes or rotational axes of the two drive shafts 1, 2 coincide.

[0080] The drive shafts 1, 2 are each coupled to an electric motor 3, 4. For example, the drive shafts 1, 2 of the drive device 50 of the Fig. 2 and Fig. 3 in the fully assembled electric bicycle 100 within the down tube 60 along the main extension direction of the down tube 60. The two electric motors 3, 4 can then be arranged in the down tube 60.

[0081] The first electric motor 3 is configured here as the main electric motor for motor-assisted propulsion of the electric bicycle. The second electric motor 4 is an auxiliary electric motor designed to provide a continuously adjustable gear ratio for manual propulsion of the electric bicycle. The second electric motor 3, in particular, has a lower power output than the first electric motor 4.

[0082] The drive device 50 of the Fig. 2 and Fig. 3 additionally comprises the pedal shaft 5, which is connected on the left and right with a pedal crank or pedals 5a, 5b (only in Fig. 2). By means of the pedals 5a, 5b, the pedal shaft 5 can be set in rotation by a pedaling movement. The pedal shaft 5 extends perpendicular to the drive shafts 1, 2. The extension of the drive shafts 1, 2 or their longitudinal axes intersect the Fig. 2 and Fig. 3 the pedal shaft 5 in the middle or do not cut the pedal shaft 5, but run past it at an angle in the middle.

[0083] The gear 10 of the drive device 50 of the Fig. 2 and Fig. 3 further includes a differential 12 in the form of a bevel gear differential. The bevel gear differential 12 has two main bevel gears 127, 128, whose rotational axes run parallel to the pedal shaft 5 or are congruent with it. The main bevel gears 127, 128 mesh with planetary bevel gears 126. The planetary bevel gears 126, in turn, are rotatably mounted on a planetary gear carrier 125, which is non-rotatably connected to the pedal shaft 5.

[0084] The first main bevel gear 127 is here connected in a rotationally fixed manner to the output element 6. The output element 6 is, for example, a chainring or a chainring carrier or a chainring spider or a pulley. The first main bevel gear 127 is part of a first bevel gear stage 11. The first bevel gear stage 11 is coupled to the first drive shaft 1 via a first spur gear stage 14.

[0085] The second main bevel gear 128 is part of a second bevel gear stage 13, which is coupled to the second drive shaft 2 via a second spur gear stage 15.

[0086] By operating the pedals 5a, 5b, the pedal shaft 5 is set in rotation. This rotation is transmitted to the planetary gear carrier 125. Consequently, the planetary bevel gears 126 also move around the rotational axis of the pedal shaft 5. However, since these are in toothed engagement with the main bevel gears 127, 128, a movement of the planetary bevel gears 126 can be associated with a rotation of the planetary bevel gears 126 around rotational axes perpendicular to the pedal shaft 5. The engagement with the main bevel gears 127, 128, in turn, under certain circumstances, ensures that the main bevel gears 127, 128 also rotate. This then results, for example, in a rotation of the output element 6. In this way, the electric bicycle can be propelled manually, i.e., by pedaling.

[0087] Whether and to what extent the first main bevel gear 127, and thus the output element 6, is driven by the pedaling movement also depends on the second drive shaft 2, which is driven by the second electric motor 4. A rotation of the second drive shaft 2 leads to a superimposed rotation of the second main bevel gear 128. This changes the transmission ratio from the pedal shaft 5 to the output element 6. Depending on how fast and in which direction the second drive shaft 2 rotates, the transmission ratio increases or decreases. The rotational speed of the second drive shaft 2 can be specified, in particular, with the aid of the coupled electric motor.

[0088] The drive device 50 of the Fig. 2 and Fig. 3 also enables additional motor-assisted propulsion of the electric bicycle 100. Torque can be transmitted from the first electric motor 3 to the output element 6 via the first spur gear stage 14 and the first bevel gear stage 11, thus providing motor-assisted propulsion of the electric bicycle.

[0089] In the Fig. 3, black arrows indicate torque paths along which the torques are transmitted from the drive shafts 1, 2 in the transmission 10. In particular, due to the bilateral arrangement of elements of the transmission 10, such as the gear stages 11, 13, 14, and 15, to the left and right of the drive shafts 1, 2, the torques coupled via the drive shafts 1, 2 are transmitted, at least in sections, to different sides of the drive shafts 1, 2. The torque is dissipated directly away from the drive shafts 1, 2 in opposite directions.

[0090] Fig. 4 and Fig. 5 show a further embodiment of the drive device 50 again in two different representations.

[0091] The difference to the embodiment of the Fig. 2 and Fig. 3 lies in the fact that a planetary gear is used as the differential 12, not a bevel gear differential. The pedal shaft 5 is rotationally fixedly connected to the sun gear 121 of the planetary gear 12. The ring gear 120 of the planetary gear 12 is coupled to the second input shaft 2 via the second bevel gear stage 13 and the second spur gear stage 15. The planet carrier 122, on which planetary gears 123 are rotatably mounted, is rotationally fixedly coupled to the output element 6. The planetary gears 123, in turn, are coupled to the ring gear 120 and the sun gear 121 via a toothed meshing.

[0092] By actuating the pedals 5a, 5b, the pedal shaft 5 is set in rotation. This rotation is transferred to the sun gear 121, which also rotates accordingly around the rotational axis of the pedal shaft 5. The meshing of the sun gear 121 with the planet gears 123 may cause the planet gears 123 to rotate. This, in turn, can lead to a rotation of the planet carrier 122, which in turn causes a rotation of the output element 6.

[0093] The rotation of the ring gear 120 can be adjusted via the coupling to the second drive shaft 2 by the connected electric motor 4. Depending on how fast and in which direction the ring gear 120 rotates, the transmission ratio from the pedal shaft 5 to the planetary carrier 122 and thus to the output element 6 changes.

[0094] As in the Fig. 2 and Fig. 3 is also in the Fig. 4 and Fig. 5, an additional motor-assisted drive of the electric bicycle is enabled by the first drive shaft 1 being coupled to the output element 6 via the first spur gear stage 14 and the first bevel gear stage 11. The bevel gear 111 of the first bevel gear stage 11 is connected to the output element 6 in a rotationally fixed manner.

[0095] In the Fig. The torque paths are again shown in Figure 5. Once again, torque is transmitted to different sides of drive shafts 1 and 2.

[0096] In the Fig. Figure 6 shows a further embodiment of the drive device 50, in which a crown gear differential with a first 130 and a second 131 main crown gear is used as the differential 12. Both are in toothed engagement with at least one epicyclic spur gear 129. The epicyclic spur gear 129 is rotatably mounted on an epicyclic carrier 125. The epicyclic carrier 125 is connected in a rotationally fixed manner to the pedal shaft 5. The first main crown gear 130 is connected in a rotationally fixed manner to the output element 6 and forms a crown gear of a first crown gear transmission stage 16, which is coupled to the first drive shaft 1. The second main crown gear 131 forms part of a second crown gear transmission stage 17, which is coupled to the second drive shaft 2. The functional principle of the stepless gear ratio adjustment between the pedal shaft 5 and the output element 6 as well as the motor support by the first electric motor 3 is as in the previous embodiments.

[0097] In the embodiment of the Fig. 6 is based on the Fig. 2 to 5 spur gear stages 14, 15 are omitted. These could also be used in the Fig. 2 to 5 are omitted. In particular, due to the omission of the spur gear stages, a rotational axis of the planetary spur gear 129 is offset in the direction of the longitudinal axis of the pedal shaft 5 relative to the longitudinal axes of the drive shafts 1, 2. Fig. 6 also shows the torque paths.

[0098] In the Fig. 6, the drive device 50 additionally has a brake 7 which is coupled to the second drive shaft 2. The brake 7 serves to counteract rotation of the second drive shaft 2 in one or both directions of rotation. To this end, the brake 7 can, when actuated, either completely block rotation (for example, by positive locking or frictional locking) or merely impede it (for example, by frictional locking). The brake is designed, for example, as a mechanical brake. The brake 7 acts on the second electric motor 4. The brake 7 can be actuated manually and / or electrically. For electrical actuation, the brake 7 is, for example, signal-connected to a control unit (not shown) of the electric bicycle in order to receive corresponding control signals.When the bike is stationary and the stationary gear ratio is adjusted, the brake can be engaged, for example, so that torque applied by the rider when starting off is not wasted in rotating the second drive shaft. This allows for a "stiff" start, for example, and achieves a comfortable ride.

[0099] Although a brake 7 is only provided on the drive device 50 of the Fig. 6, such a brake can also be used in the drive devices 50 of the Fig. 2 to 5 are used.

[0100] Overall, in all embodiments, the interlocking of the drive shafts 1, 2 results in a particularly compact design of the drive device 50. This effect is reinforced by the bilateral torque transmission to the left and right of the longitudinal axes of the drive shafts 1, 2, as is the case in all embodiments.

[0101] In the previous embodiments, the pedal shaft 5 was always rotationally fixedly connected to a component of the differential 12. Alternatively, the pedal shaft 5 could also be coupled to the component via a freewheel. Furthermore, in the previous embodiments, the output element 6 was rotationally fixedly connected to a bevel gear 111, 127, or crown gear 130 of the first bevel gear stage 11 or crown gear stage 16. However, a coupling between the bevel gear 111, 127, or crown gear 130 and the output element 6 via a freewheel could also be used instead.

[0102] In the embodiment of the Fig.7, the differential 12 is a stepped planetary gear with two sun gears 121, 124 and a planet carrier 122. Planet gears 123a, 123b are rotatably mounted on the planet carrier 122 and mesh with either the first sun gear 121 or the second sun gear 124. The planet gears 123a, 123b are particularly connected to one another in a rotationally fixed manner.

[0103] The first sun gear 121 is coupled to the second input shaft 2 via the second bevel gear stage 13 and the second spur gear stage 15. The second sun gear 124 is rotationally fixedly connected to the output element 6. The planet carrier 122 is coupled to the pedal shaft 5 via a freewheel 9. Alternatively, a rotationally fixed connection could also be provided between the pedal shaft 5 and the planet carrier 122.

[0104] Furthermore, a freewheel 8 is provided between the output element 6 and the bevel gear 111 of the first bevel gear stage 11, so that, during rotation in one direction, torque can be transferred from the bevel gear 111 to the output element 6, while the bevel gear 111 and the output element 6 rotate at the same speed. This prevents the electric motor 4 from "dragging," which leads to less resistance when pedaling in operating states without motor assistance from the electric motor 4. List of reference symbols: 1 first drive shaft 2 second drive shaft 3 first electric motor 4 second electric motor 5 Pedal shaft 6 Output element 7 Brake 8 Freewheel 9 Freewheel 10 gearboxes 11 first bevel gear stage 12 Differential 13 second bevel gear stage 14 first spur gear stage 15 second spur gear stage 16 first crown gear stage 17 second crown gear stage 50 drive device 60 down tube 70 bicycle frames 100 electric bikes 111 Bevel gear 120 ring gear 121 Sun gear 122 planet carrier 123 Planetary gear 123a planetary gear 123b Planetary gear 124 Sun gear 125 idler gear carrier 126 Bevel gear 127 first main bevel gear 128 second main bevel gear 129 Orbiting spur gear 130 first main crown wheel 131 second main crown wheel

Claims

[1] Drive device (50) for an electric bicycle (100), comprising - a transmission (10) with a first drive shaft (1), a second drive shaft (2) and an output element (6), wherein - torque of a first electric motor can be coupled into the transmission (10) via the first drive shaft (1), - torque of a second electric motor can be coupled into the transmission (10) via the second drive shaft (2), - torque can be dissipated from the gearbox (10) via the output element (6), - the first (1) and the second (2) drive shaft (1) run parallel to each other, - one drive shaft (2) is guided through the other drive shaft (1), - the transmission (10) has a bevel gear stage (11) which is coupled on the one hand to the first drive shaft (1) and on the other hand to the output element (6), and - a bevel gear (111, 127) of the bevel gear stage (11) is coupled to the output element (6) for torque transmission in at least one direction of rotation without changing the speed. [2] Drive device (50) according to claim 1, wherein - the torques fed in via the two drive shafts (1, 2) are transmitted within the transmission (10) at least in sections on different sides of the drive shafts (1, 2). [3] Drive device (50) according to claim 1 or 2, further comprising - a first electric motor (3) coupled to the first drive shaft (1), - a second electric motor (4) coupled to the second drive shaft (2), wherein - the two electric motors (3, 4) are arranged one behind the other in the direction of the longitudinal axes of the first (1) and second (2) drive shaft. [4] Drive device (50) according to one of the preceding claims, wherein - the transmission (10) is designed to transmit torque from an electric motor coupled to the first drive shaft (1) to the output element (6) in order to propel the electric bicycle with the aid of the motor. [5] Drive device (50) according to one of the preceding claims, wherein - the transmission (10) has a pedal shaft (5) which runs transversely or perpendicularly to the drive shafts (1, 2), wherein - the transmission (10) is designed to transmit torque from the pedal shaft (5) to the output element (6) in order to propel the electric bicycle (100) by a pedaling movement. [6] Drive device (50) according to claim 5, wherein - the longitudinal axes of the drive shafts (1, 2) cross or pass the pedal shaft (5) essentially in or at the center of the pedal shaft (5). [7] Drive device according to claim 5 or 6, wherein - the transmission (10) is arranged in such a way that a transmission ratio of the torque transmission from the pedal shaft (5) to the output element (6) can be adjusted by rotation of the second drive shaft (2). [8] Drive device (50) according to claim 7, wherein - the transmission (10) has a differential (12) in the form of a bevel gear differential or a planetary gear or a stepped planetary gear or a crown gear differential for adjusting the transmission ratio. [9] Drive device (50) according to claim 8, wherein - the differential (12) is a planetary gear, - the second drive shaft (2) is coupled to a ring gear (120) of the planetary gear (12), - the pedal shaft (5) is connected in a rotationally fixed manner to a sun gear (121) of the planetary gear (12), - the output element (6) is connected in a rotationally fixed manner to a planet carrier (122) of the planetary gear (12). [10] Drive device (50) according to claim 8, wherein - the differential (12) is a stepped planetary gear, - the second drive shaft (2) is coupled to a sun gear (121) of the stepped planetary gear (12), - the pedal shaft (5) is coupled to a planet carrier (122) of the stepped planetary gear (12), - the output element (6) is coupled to a further sun gear (124) of the stepped planetary gear (12). [11] Drive device (50) according to claim 8, wherein - the differential (12) is a bevel gear differential, - a planetary gear carrier (125) of the bevel gear differential (12) is connected to the pedal shaft (5) in a rotationally fixed manner, - at least one planetary bevel gear (126) is arranged on the planetary gear carrier (125), - the output element (6) is coupled in a rotationally fixed manner to a first main bevel gear (127) of the bevel gear differential gear (12), wherein the first main bevel gear (127) is in engagement with the at least one planetary bevel gear (126), - the second drive shaft (2) is coupled to a second main bevel gear (128) of the bevel gear differential gear (12), wherein the second main bevel gear (128) is in engagement with the at least one planetary bevel gear (126). [12] Drive device (50) according to claim 11, wherein - the first (127) and the second (128) main bevel gear are arranged on different sides of the drive shafts (1, 2). [13] Drive device (50) according to one of the preceding claims, wherein - the transmission (10) has a further bevel gear stage (13) which is coupled to the second drive shaft (2), - the bevel gear stage (11) and the further bevel gear stage (13) are arranged on different sides of the drive shafts (1, 2). [14] Drive device (50) according to claim 8, wherein - the differential (12) is a crown gear differential, - a planetary gear carrier (125) of the crown gear differential gear (12) is connected to the pedal shaft (5) in a rotationally fixed manner, - at least one planetary spur gear (129) is arranged on the planetary gear carrier (125), - the output element (6) is coupled in a rotationally fixed manner to a first main crown gear (130) of the crown gear differential gear (12), wherein the first main crown gear (130) is in engagement with the at least one planetary spur gear (129), - the second drive shaft (2) is coupled to a second main crown gear (131) of the crown gear differential gear (12), wherein the second main crown gear (131) is in engagement with the at least one planetary spur gear (129). [15] Electric bicycle (100) having - a drive device (50) according to one of the preceding claims, - a down tube (60), wherein - the two drive shafts (1, 2) extend substantially parallel to the main direction of extension of the down tube (60).

Images