Drive device for an electric bicycle, and electric bicycle

Abstract

In at least one embodiment, the drive device (50) for an electric bicycle (100) has a gear mechanism (10) with a first driveshaft (1), a second driveshaft (2), and an output element (6). The torque of a first electric motor can be coupled into the gear mechanism via the first driveshaft, and the torque of a second electric motor can be coupled into the gear mechanism via the second driveshaft. The torque can be output from the gear mechanism via the output element. The torques supplied by the two driveshafts are at least partially transferred to different sides of the driveshafts within the gear mechanism.

Description

[0001] Description

[0002] Drive device for an electric bicycle and electric bicycle

[0003] A drive device for an electric bicycle is specified. Furthermore, an electric bicycle is specified.

[0004] 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 particularly suited to various sporting activities have emerged.

[0005] In recent years, enthusiasm for electric bicycles (especially so-called "pedelecs") has grown, despite the high weight and price of bicycles. With electric bicycles, it's important to provide a reliable, supportive drive system that enables high power transmission.

[0006] 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.

[0007] These objects are achieved, inter alia, by the subject matter of patent claims 1 and 21. Advantageous embodiments and further developments are the subject matter of the remaining, dependent patent claims and will further emerge from the following description and the figures. First, the drive device for an electric bicycle is specified.

[0008] 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 can be dissipated from the transmission via the output element.

[0009] The transmission comprises, in particular, a plurality of intermeshing gears. In particular, the transmission comprises one or more gear stages. A gear stage is understood to be a pair of intermeshing gears. A toothed interface is formed between the pair of intermeshing gears.

[0010] The transmission converts, for example, a rotation of the first drive shaft into a rotation of the output element. Alternatively or additionally, the transmission can convert a rotation of the second drive shaft into a rotation of the output element. In particular, the transmission is designed to transmit torque from the first and / or second drive shaft to the output element. The transmission is designed, for example, such that the first and second drive shafts can rotate independently of one another. For example, the second drive shaft can also rotate independently of the output element. The output element is, for example, a chainring or a chainring carrier or a chainring spider or a pulley.

[0011] According to at least one embodiment, torques fed in via the two drive shafts are transmitted within the transmission at least in sections on different sides of the drive shafts. In other words, the transmission is constructed such that the torque fed into the transmission via the first drive shaft is transmitted at least in sections on one side of the drive shafts. The torque fed into the transmission via the second drive shaft is transmitted at least in sections on the opposite side 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.

[0012] By transmitting torque on both sides of the drive shafts, the installation space available for the drive device can be used efficiently.

[0013] “On different sides of the drive shafts” means in particular on different sides of a virtual plane which, viewed over the entire length of the two drive shafts, has the smallest square distance to both drive shafts. The transmission is, for example, set up such that this virtual plane runs parallel to the longitudinal axes of the drive shafts. Alternatively or additionally, the transmission can be set up so that this virtual plane runs transversely or perpendicularly to the axis of rotation of the output element and / or transversely or perpendicularly to the axis of rotation / longitudinal axis of a pedal shaft of the drive device. If the drive device is viewed from a direction parallel to the virtual plane and such that the virtual plane extends in a vertical direction, i.e. from top to bottom, the two different sides are the half-spaces to the right and left of the virtual plane.

[0014] To implement torque transmission to the different sides of the drive shafts, the transmission comprises at least one gear or at least one gear stage on one side of the drive shafts and at least one gear 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.

[0015] 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 that 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 or the virtual plane.

[0016] According to at least one embodiment, the two drive shafts run in a common plane. This means that the longitudinal axes of the drive shafts lie in this common plane. The common plane then forms the virtual plane described above. The drive shafts or their longitudinal axes can run parallel to one another or at an angle of, for example, at most 120° or at most 90° or at most 30° to one another. The longitudinal axes of the two drive shafts intersect, for example, at a point in the common plane. The common plane of the two drive shafts is, for example, perpendicular to the axis of rotation of the pedal shaft and / or the output element.

[0017] According to at least one embodiment, one drive shaft is guided or inserted through the other drive shaft. Either the first drive shaft can be guided through the second drive shaft or the second drive shaft can be guided through the first drive shaft. A drive shaft is in particular a hollow shaft through which the other drive shaft is guided. The first and the second drive shaft are in particular coaxial to an axis. This axis forms, for example, a rotation axis for both the first and the second drive shaft.

[0018] By passing 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.

[0019] 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.

[0020] 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 direction of rotation, the first electric motor can be operated, for example, as a motor and generator.

[0021] 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.

[0022] The drive device is in particular designed such that rotation of the second electric motor is possible in both directions of rotation (in the event that the brake introduced further down is opened). The second electric motor can, for example, only be operated as a motor in one of the two directions of rotation. In this one direction of rotation, operation of the second electric motor as a generator 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 as a generator in both directions of rotation.

[0023] Two elements can be coupled directly or indirectly. "Coupled" here means in particular that the rotation of one element leads to the rotation of the other. Direct coupling here means in particular that there is no translation or reversal of the direction of rotation between the elements. Indirect coupling here means in particular that there is a translation and / or change of direction of rotation between the elements. Indirectly coupled elements are coupled to one another, for example, via a gear stage. Directly coupled elements can be connected to one another in a rotationally fixed manner.

[0024] The first electric motor, for example, forms a main motor. The second electric motor then forms, for example, 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 the maximum torque of the main motor is at least 1.5 times, or at least twice, or at least 3 times greater than that of the auxiliary motor.

[0025] 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 axis of rotation of the output element also runs, for example, transversely or perpendicularly to the longitudinal axes of the drive shafts. In particular, the axis of rotation of the output element and the axis of rotation of the pedal shaft are parallel or congruent. The drive device is, for example, an orthogonal drive.

[0026] Alternatively, the pedal shaft can also run parallel to one or both drive shafts or their longitudinal axes. For example, the rotational axis of the output element also runs parallel to one or both drive shafts or their longitudinal axes.

[0027] 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 connected in a rotationally fixed manner to a gear of this first gear stage.

[0028] 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 driven by the motor.

[0029] 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 .

[0030] According to at least one embodiment, the drive device is a parallel hybrid drive. "Hybrid" means that the electric bicycle is propelled forward via the drive device either by muscle power or by a supporting electric motor (here the electric motor coupled to the first drive shaft), or by both together. When both work together, i.e. pedaling movement and supporting electric motor, a torque resulting from the electric motor and a torque resulting from the pedaling movement are added at a junction. The speed resulting from the electric motor at the junction and the speed resulting from the pedaling movement at the junction are the same. The junction is, for example, the output element or a transmission element connected to it in a rotationally fixed manner. The term "parallel" comes from this addition of torque.

[0031] 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.

[0032] According to at least one embodiment, the transmission is configured such that a transmission ratio for the torque transmission or 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 be used to achieve continuously variable shifting, i.e., continuously varying the transmission ratio. The second drive shaft therefore does not serve, 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.

[0033] 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 constructed such that rotation in both opposite directions of rotation of the second drive shaft is generally possible (for example, when a brake introduced further downstream is released).

[0034] 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 the present case, this stationary gear ratio does not preferably form the lowest gear, i.e. the smallest possible gear ratio. Rather, the gear or the gear ratio can be increased or decreased (continuously) from the stationary gear ratio, simply by rotating the second drive shaft in one or the other direction of rotation. How high the highest gear ratio or the highest gear of the transmission is and how low the lowest gear ratio or the lowest 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.For example, the (maximum) rotation speed in one direction of rotation can be specified by operating the electric motor as a motor. In the other direction of rotation, 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 of rotation can also be specified by operating the electric motor as a motor.

[0035] 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 (An) 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 nl+l / 4-An and nl+2 / 5-An, or exactly nl+l / 3-An. Here, nl is the specified lowest gear ratio of the drive system, n2 is the specified highest gear ratio of the drive system, and An = n2-nl is the speed spread.

[0036] According to at least one embodiment, the transmission has a differential for adjusting the gear ratio by means of rotation of the second drive shaft. The differential can be a bevel gear differential, a planetary gear, a stepped planetary gear, or a crown gear differential. For this purpose, the differential is coupled in particular to the first and second drive shafts, the pedal shaft, and the output element.

[0037] According to at least one embodiment, the transmission is configured such that torque can be transmitted from the first drive shaft to the output element, and the path of this torque transmission does not pass through a gear stage of the differential. In other words, the path of torque transmission from the first drive shaft to the output element does not pass through a toothed interface of the differential. However, the path passes through at least one toothed interface or gear stage of the transmission that does not belong to the differential. This means that the toothed interfaces of the differential do not see the torque transmitted from the first drive shaft to the output element. In particular, the path of torque transmission passes through at most one gear of the differential. This gear is, for example, one of the following gears introduced below: sun gear, ring gear, main bevel gear, main crown gear.In particular, the torque transmitted from the first input shaft to the output element does not pass through or traverse any planetary gear or planetary gear of the differential.

[0038] The transmission design described above allows for a compact design and minimizes differential wear.

[0039] The torque fed into the transmission by the second drive shaft passes, for example, through at least one gear stage of the differential. According to at least one embodiment, the differential is a planetary gear. For example, the second drive shaft is coupled, for example indirectly coupled, to a ring gear of the planetary gear. The pedal shaft is coupled, for example, to a sun gear of the planetary gear, in particular connected in a rotationally fixed manner or coupled via a freewheel. The output element is coupled, for example, to a planet carrier of the planetary gear, in particular connected in a rotationally fixed manner. The first drive shaft can be coupled to the planet carrier, in particular indirectly coupled.

[0040] 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.

[0041] According to at least one embodiment, the differential is a stepped planetary gear. The stepped planetary gear comprises, for example, two sun gears or two ring gears or a sun gear and a ring gear. In the first case, 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.

[0042] 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

[0043] 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 meshes with the at least one epicyclic bevel gear. For example, the first drive shaft is coupled, in particular indirectly coupled, to the first main bevel gear.

[0044] One, two or more

[0045] Circulating bevel gears are arranged, each of which meshes with the first and second main bevel gear. The

[0046] The planetary 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.

[0047] The rotational axes of the two main bevel 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

[0048] The rotating bevel gear runs in particular transversely or perpendicularly to the axis of rotation of the output element or the pedal shaft.

[0049] According to at least one embodiment, the first and second main bevel gears are arranged on different sides of the drive shafts. In particular, one main bevel gear is located on one side of the virtual plane or the common plane, and one main bevel gear is located on the other side of the virtual or common plane. This allows for a space-saving and compact design.

[0050] 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 direction of rotation, specifically 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 direction of rotation, with the bevel gear and the output element rotating at the same speed. The axes of rotation of the bevel gear and of 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.For example, the bevel gear of the first bevel gear stage is (only) coupled to the output element via a freewheel or is connected to the output element in a rotationally fixed manner.

[0051] 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, hereinafter also referred to 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.

[0052] 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.

[0053] If the differential is a planetary gear, 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 coupled to the planet carrier in a rotationally fixed manner. The second drive shaft is coupled, for example, to the ring gear of the planetary gear via the second bevel gear stage. In particular, the ring gear can be connected in a rotationally fixed manner to a bevel gear of the second bevel gear stage or can form this bevel gear. If the differential is a bevel gear differential, the first drive shaft is coupled, for example, to the first main bevel gear via the first bevel gear stage. The first main bevel gear can be connected in a rotationally fixed manner to a bevel gear of the first bevel gear stage or can form this bevel gear.The second drive shaft is coupled, for example, to the second main bevel gear via the second bevel gear stage. The second main bevel gear can be connected in a rotationally fixed manner to a bevel gear of the second bevel gear stage or form this bevel gear.

[0054] 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 particular, one bevel gear stage is located on one side of the virtual or common plane, and one bevel gear stage is located on the other side of the virtual or common plane. This allows for a space-saving and compact design.

[0055] 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 planetary 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

[0056] The second drive shaft can be coupled, in particular indirectly coupled, to a second main crown gear of the crown gear differential gear, wherein the second main crown gear is in engagement with the at least one revolving spur gear. For example, the first drive shaft is coupled, in particular indirectly coupled, to the first main crown gear.

[0057] One, two or more planetary spur gears can be arranged on the planetary gear carrier, each of which meshes with the first and second main crown gear.

[0058] 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

[0059] The rotation of the spur gear runs in particular transversely or perpendicularly to the axis of rotation 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 particular, one main crown gear is located on one side of the virtual or common plane, and one main crown gear is located on the other side of the virtual or common plane. This allows for a space-saving and compact design.

[0061] According to at least one embodiment, the first and second 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.

[0062] 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 is located at a distance of between 0.4 and 0.6 times, or in the range of between 0.45 and 0.55 times, the length of the pedal shaft from a longitudinal end of the pedal shaft.

[0063] If the longitudinal axes of the drive shafts do not cross the pedal shaft but run past it at an angle, the first and second bevel gear stages can be designed as hypoid bevel gear stages, for example.

[0064] 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.

[0065] 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 about the longitudinal axis of the second drive shaft.

[0066] The brake can be designed such that it completely blocks or locks rotation in at least one direction of rotation. Alternatively or additionally, the brake can be designed such that the braking force it exerts is adjustable. Depending on the set braking force, the brake can therefore impede rotation of the second drive shaft in at least one direction of rotation to varying degrees, optionally even blocking it completely. Complete blocking can be achieved, for example, by a positive engagement. Making rotation more difficult or even completely blocked, i.e. adjusting the braking force, can be achieved, for example, by frictional engagement.

[0067] 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 coupleable 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.

[0068] 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 a 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, rotation of the second drive shaft in both directions of rotation is blocked by the brake when starting from a standstill.

[0069] 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 actuated in order to completely block rotation of the second drive shaft. For example, the brake comprises a freewheel for blocking rotation of the second drive shaft in only one direction of rotation.

[0070] According to at least one embodiment, the brake is designed such that it generates a braking effect for both directions of rotation of the second drive shaft by means of frictional engagement. This means that when the brake is actuated, it counteracts rotation of the second drive shaft in both directions of rotation by means of frictional engagement. According to at least one embodiment, the brake is designed to decelerate an existing rotation of the second drive shaft. For example, the brake is designed to decelerate or counteract a rotation of the second drive shaft which sets a lower gear than the stationary gear ratio. Alternatively or additionally, the brake can be designed to decelerate or counteract a rotation of the second drive shaft which sets a higher gear than the stationary gear ratio.

[0071] 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 closely counteracted. In particular, the frictional force with which the brake achieves its braking effect can be increased or decreased.

[0072] Furthermore, it is also possible that the brake is an electromagnetic brake, for example a magnetic brake or eddy current brake.

[0073] Next, the electric bicycle is specified. The electric bicycle is specifically a pedelec.

[0074] In at least one embodiment, the electric bicycle comprises a drive device according to one of the embodiments described here. The electric bicycle further comprises a down tube. The two drive shafts extend in the down tube, for example, 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.

[0075] Since the electric bicycle has a drive device as described here, all features disclosed in connection with the drive device are also disclosed for the electric bicycle and vice versa.

[0076] 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 symbols 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 symbols in all illustrations.

[0077] It shows :

[0078] Figure 1 shows an example of an electric bicycle,

[0079] Figures 2 to 7 show various embodiments of a drive device.

[0080] Figure 1 schematically shows an electric bicycle 100 with a bicycle frame 70, which, among other things, has a lower frame section 60 forming a down tube. The frame section 60 extends towards a bottom bracket, which comprises a pedal shaft 5. The pedal shaft 5 is part of a drive device 50 for the electric bicycle 100. The following Figures 2 to 6 show exemplary embodiments of this drive device 50. Bearings for relative rotation between the adjacent elements are represented as black rectangles.

[0081] Figures 2 and 3 show an exemplary 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.

[0082] In the present case, the first drive shaft 1 and the second drive shaft 2 lie in a common, virtual plane which is perpendicular to the axis of rotation of the pedal shaft 5 (and perpendicular to the plane of the paper). The drive shafts 1, 2 are arranged here on different sides of the pedal shaft 5. Their longitudinal axes are parallel to one another. Alternatively, the two drive shafts 1, 2 could also lie in the common, virtual plane and be arranged on the same side of the pedal shaft 5, for example above the pedal shaft. For example, the longitudinal axes of the two pedal shafts then enclose an angle of at most 30° with one another.

[0083] 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 Figures 2 and 3 extend inside the down tube 60 along the down tube 60 in the fully assembled electric bicycle 100. The two electric motors 3, 4 can then be arranged in the down tube 60.

[0084] 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 for a continuously adjustable gear ratio for manual propulsion of the electric bicycle. In particular, the second electric motor 3 has a lower power output than the first electric motor 4.

[0085] The drive device 50 of Figures 2 and 3 additionally comprises the pedal shaft 5, which is connected on the left and right to a pedal crank or pedals 5a, 5b (only shown in Figure 2). With the help 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 in Figure

[0086] 2 and 3 the pedal shaft 5 in the middle or do not intersect the pedal shaft 5, but run past it at an angle in the middle.

[0087] The gear 10 of the drive device 50 of Figures 2 and

[0088] 3 further comprises a differential 12 in the form of a bevel gear differential. The bevel gear differential 12 has two main bevel gears 127, 128, whose axes of rotation run parallel to the pedal shaft 5 or are congruent therewith. The main bevel gears 127, 128 mesh with epicyclic bevel gears 126. The epicyclic bevel gears 126 are in turn rotatably arranged on an epicyclic gear carrier 125 which is connected in a rotationally fixed manner to the pedal shaft 5. The first main bevel gear 127 is in this case rotationally fixedly connected to the output element 6. The output element 6 is, for example, a chainring or a chainring carrier or a chainring spider or a belt pulley. The first main bevel gear 127 is part of a first bevel gear transmission stage 11. The first bevel gear stage 11 is coupled to the first drive shaft 1 via a first spur gear stage 14.

[0089] 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.

[0090] By actuating 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 about the axis of rotation 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 linked to a rotation of the planetary bevel gears 126 about axes of rotation perpendicular to the pedal shaft 5. The engagement with the main bevel gears 127, 128 in turn ensures, under certain circumstances, 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.

[0091] Whether and to what extent the first main bevel gear 127 and thus the

[0092] Output element 6 is driven by the pedaling movement, but is also connected to 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 becomes larger or smaller. The rotational speed of the second drive shaft 2 can be specified in particular with the aid of the coupled electric motor.

[0093] The drive device 50 of Figures 2 and 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.

[0094] In Figure 3, black arrows indicate torque paths along which the torques from the drive shafts 1, 2 are conducted 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 or to the left and right of the virtual plane, the torques coupled in via the drive shafts 1, 2 are passed on at least in sections to different sides of the drive shafts 1, 2. The torque is diverted directly away from the drive shafts 1, 2 in opposite directions. Figures 4 and 5 show a further exemplary embodiment of the drive device 50, again in two different representations.

[0095] The difference from the exemplary embodiment in Figures 2 and 3 is that here, instead of a bevel gear differential, a planetary gear is used as the differential 12. The pedal shaft 5 is connected in a rotationally fixed manner 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 planet gears 123 are rotatably mounted, is rotationally fixedly coupled to the output element 6. The planet gears 123 are coupled to the ring gear 120 and the sun gear 121 via a toothed meshing.

[0096] By actuating the pedals 5a, 5b, the pedal shaft 5 is set in rotation. This rotation is transmitted to the sun gear 121, which also rotates accordingly around the rotation axis of the pedal shaft 5. The meshing of the sun gear 121 with the planet gears 123 may cause the latter 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.

[0097] The rotation of the ring gear 120 can be adjusted via the coupling to the second drive shaft 2 by the electric motor 4 connected thereto. Depending on how fast and in which direction the ring gear 120 is rotated, the transmission ratio from the pedal shaft 5 to the planet carrier 122 and thus to the output element 6 changes. As in Figures 2 and 3, an additional motor-assisted drive of the electric bicycle is also possible in Figures 4 and 5 in that the first drive shaft 1 is 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.

[0098] The torque paths are again shown in Figure 5. Once again, torque is transmitted to different sides of the drive shafts 1 and 2.

[0099] Figure 6 shows a further exemplary embodiment of the drive device 50, in which a crown gear differential gear 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 rotating spur gear 129. The rotating spur gear 129 is rotatably mounted on a rotating carrier 125. The rotating gear 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 continuously variable transmission ratio adjustment between the pedal shaft 5 and the output element 6, as well as the motor assistance by the first electric motor 3, is the same as in the previous embodiments. In the embodiment of Figure 6, the spur gear stages 14, 15 used in Figures 2 to 5 are omitted. These could also be omitted in Figures 2 to 5. Particularly due to the omission of the spur gear stages, a rotational axis of the revolving spur gear 129 is in the direction of the longitudinal axis of the pedal shaft.

[0100] 5 offset from the longitudinal axes of the drive shafts 1 , 2 . Figure

[0101] 6 also shows the torque paths.

[0102] In Figure 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 a rotation of the second drive shaft 2 in one or both directions of rotation. For this purpose, the brake 7 can, when actuated, either completely block a rotation (for example, by form-fitting or frictional engagement) or only impede it (for example, by frictional engagement). The brake is designed, for example, as a mechanical brake. The brake

[0103] 7 acts on the second electric motor 4 . The brake 7 can be operated manually and / or electrically . For electrical operation, 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 bicycle is stationary and the stationary gear ratio is set, the brake can be activated, for example, so that any torque applied by the rider when starting off is not wasted in rotating the second drive shaft. This allows, for example, a "stiff" start and a pleasant riding experience is achieved.

[0104] Although a brake 7 is only shown in the drive device 50 of Figure 6, such a brake can also be used in the drive devices 50 of Figures 2 to 5.

[0105] Overall, in all embodiments, the transmission of the torques on different sides of the drive shafts 1, 2 results in a particularly compact design of the drive device 50.

[0106] In the previous embodiments, the pedal shaft 5 was always connected in a rotationally fixed manner to a component of the differential 12. Alternatively, however, the pedal shaft 5 could also be coupled to the component via a freewheel. Furthermore, in the previous embodiments, the output element 6 was connected in a rotationally fixed manner to a bevel gear 111, 127 or crown gear 130 of the first bevel gear stage 11 or the crown gear stage 16. Instead, however, a coupling between the bevel gear 111, 127 or the crown gear 130 and the output element 6 via a freewheel could also be used.

[0107] In the embodiment of Figure 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 121 or the second 124 sun gear. The planet gears 123a, 123b are, in particular, connected to one another in a rotationally fixed manner.

[0108] 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 connected in a rotationally fixed manner 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.

[0109] 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, upon 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 "dragging" of the electric motor 4, which leads to less resistance when pedaling in operating conditions without motor assistance from the electric motor 4.

[0110] In Figure 7, the second drive shaft 2 is guided through the first drive shaft 1.

[0111] In all the embodiments shown, the torque transmission path from the first drive shaft 1 to the output element 6 does not pass through any gear stage, i.e. no toothed interface, of the differential 12.

[0112] The invention is not limited to the embodiments described herein. Rather, the invention encompasses any novel feature and any combination of features, including, in particular, any combination of features in the claims, even if these features or this combination itself is not explicitly stated in the claims or embodiments. List of reference symbols:

[0113] 1 first drive shaft

[0114] 2 second drive shaft

[0115] 3 first electric motor

[0116] 4 second electric motor

[0117] 5 Pedal shaft

[0118] 6 Output element

[0119] 7 Brake

[0120] 8 Freewheel

[0121] 9 Freewheel

[0122] 10 gearboxes

[0123] 11 first bevel gear stage

[0124] 12 Differential

[0125] 13 second bevel gear stage

[0126] 14 first spur gear stage

[0127] 15 second spur gear stage

[0128] 16 first crown gear stage

[0129] 17 second crown gear stage

[0130] 50 drive device

[0131] 60 down tube

[0132] 70 bicycle frames

[0133] 100 electric bikes

[0134] 111 Bevel gear

[0135] 120 ring gear

[0136] 121 Sun gear

[0137] 122 planetary carriers

[0138] 123 Planetary gear

[0139] 123a planetary gear

[0140] 123b Planetary gear

[0141] 124 Sun gear

[0142] 125 idler gear carrier

[0143] 126 Circulation bevel gear first main bevel gear second main bevel gear Circulation spur gear first main crown gear second main crown gear

Claims

Patent 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 gear (10) has a pedal shaft (5), - 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, - 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), - the transmission (10) has a differential (12) for adjusting the transmission ratio, - the transmission (10) is arranged in such a way that the torque can be transmitted from the first drive shaft (1) to the output element (6) and the path of this torque transmission does not pass through any gear stage of the differential (12).

2. Drive device (50) according to claim 1 or 2, wherein - the differential (12) is a stepped planetary gear.

3. Drive device (50) according to claim 2, wherein the stepped planetary gear has either two sun gears or two ring gears or one sun gear and one ring gear.

4. Drive device (50) according to one of the preceding claims, wherein - the first (1) and the second (2) drive shaft (1) run in a common plane.

5. Drive device (50) according to claim 4, wherein the - the first (1) and second (2) drive shafts run parallel to each other.

6. Drive device (50) according to claim 5, wherein - one drive shaft (2) is guided through the other drive shaft (1).

7. Drive device (50) according to one of the preceding claims, wherein - 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).

8. Drive device (50) according to one of the preceding claims, wherein - 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).

9. Drive device (50) according to claim 8, wherein - a bevel gear (111, 127) of the bevel gear stage (11) for torque transmission in at least one Direction of rotation without change in speed is coupled to the output element (6).

10. Drive device (50) according to one of the preceding claims, 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).

11. Drive device (50) according to one of the preceding claims, wherein - the pedal shaft (5) runs transversely or perpendicularly to the drive shafts (1, 2).

12. 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.

13. Drive device (50) according to one of claims 1 or 4 to 12, wherein - the differential (12) is a bevel gear differential or a planetary gear or a crown gear differential.

14. Drive device (50) according to claim 13, 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 to a sun gear (121) of the planetary gear (12) in a rotationally stable manner, - the output element (6) is rotationally connected to a planet carrier (122) of the planetary gear (12).

15. Drive device (50) according to claim 2 or one of claims 3 to 12 with reference to claim 2, 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).

16. Drive device (50) according to claim 13, wherein - the differential (12) is a bevel gear differential, - a planetary gear carrier (125) of the bevel gear differential (12) is connected in a rotationally fixed manner to the pedal shaft (5), - at least one 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).

17. Drive device (50) according to claim 16, wherein - the first (127) and the second (128) main bevel gear are arranged on different sides of the drive shafts (1, 2).

18. Drive device (50) according to claim 8 or one of claims 9 to 17 with reference to claim 8, wherein - the transmission (10) has a further bevel gear stage (13) which is coupled to the second drive shaft (2).

19. Drive device (50) according to claim 18, wherein - the bevel gear stage (11) and the further Bevel gear stage (13) are arranged on different sides of the drive shafts (1, 2).

20. Drive device (50) according to claim 13, 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 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 revolution spur gear (129), - the second drive shaft (2) with 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 revolution spur gear (129).

21. Drive device (50) according to claim 20, wherein - the first (130) and the second (131) main crown gear are arranged on different sides of the drive shafts (1, 2).

22. 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 in the down tube (60).

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