Drive train for a bicycle

Abstract

The invention relates to a drive train, which is designed for a continuously variable transmission ratio between a crankshaft (10) and a driveshaft (12). The transmission (14) comprises three planetary gear sets (20, 30, 40). A first motor shaft (W1) is permanently connected to a first sun gear (22) in a rotationally fixed manner. A first planet carrier (24) is permanently connected to a second ring gear (36) in a rotationally fixed manner. The first planet carrier (24) can be connected to a third sun gear (42) in a rotationally fixed manner. A first ring gear (26) is permanently connected to a second sun gear (32) in a rotationally fixed manner. A third planet carrier (44) can be connected to the crankshaft (10) in a rotationally fixed manner. A third ring gear (46) can be connected to the drive shaft (12) in a rotationally fixed manner. The second planetary gear set (30) is nested radially outward with the first planetary gear set (20).

Description

[0001] Drivetrain for a bicycle

[0002] Technical area

[0003] The present invention relates to a drive train for a bicycle.

[0004] State of the art

[0005] On bicycles, gear shifting is an important component for enabling comfortable riding with different gears. The more precisely a gear ratio in a bicycle's drivetrain can be adjusted to the current riding speed, the better a rider can pedal at a comfortable cranking speed. However, such adaptability of the gear ratio usually requires a complex transmission that requires a lot of space. When the transmission is arranged in a bicycle frame, however, the space is very limited. A wide gear ratio spread is also desirable in order to easily manage steep inclines while still being able to achieve high riding speeds.

[0006] Modern bicycles are also often built with electric drive assistance. Such bicycles are also known as pedelecs. This allows even people with limited physical fitness to ride comfortably. When using electric motors for drive assistance, the ability to adjust the gear ratio is also desirable, so that the electric drive assistance can operate efficiently.

[0007] DE 10 2015 208 355 A1 describes a vehicle with a planetary transmission, the design of which is said to be particularly suitable for electric vehicles. Description of the invention

[0008] A first aspect relates to a drive train for a bicycle. A bicycle can be designed, for example, as a human-powered vehicle or as a pedelec. At least part of a drive force can be provided, for example, by a rider. A bicycle has, for example, a bicycle frame and at least two wheels rotatably mounted thereon. The drive train can be designed to provide a drive force to at least one of these driven wheels.

[0009] The drivetrain has a crankshaft. Crank arms with rotatably mounted pedals can be attached to the crankshaft. A rider of the vehicle can apply muscle power to the crankshaft via the pedals, for example, using their legs. Muscle power can be transferred to the drivetrain via the crankshaft. The crankshaft can, for example, be designed as a central shaft that extends transversely through a bicycle frame. The crankshaft and, optionally, the entire drivetrain can be mounted on a bottom bracket area of ​​the bicycle frame.

[0010] The drivetrain has an output shaft. The output shaft can be connected to a vehicle's wheel via a power transmission element. For example, the output shaft can be connected to a vehicle's wheel via a chain or belt. A pinion, for example, can be permanently and non-rotatably attached to the output shaft. The output shaft can be arranged coaxially to the crankshaft, for example.

[0011] The drive train has a first electric machine with a first motor shaft. In addition to the first electric machine, the drive train can have further electric machines. Alternatively, the drive train can be free of additional electric machines. The first electric machine can be designed to provide drive power to the first motor shaft. The numbering as the first motor shaft can merely serve to assign it to the first electric machine. The first electric machine can therefore be free of further motor shafts. The first electric machine can, for example, change a gear ratio from the crankshaft to the output shaft by rotating the first motor shaft. Alternatively or additionally, this can also provide drive power for the output shaft, for example.

[0012] An electrical machine can be designed to convert electrical energy into mechanical energy. Alternatively or additionally, an electrical machine can be designed for recuperation. An electrical machine can be designed, for example, as an asynchronous motor or synchronous motor. The drive train can have an energy storage device, for example an accumulator. The energy storage device can be used to supply respective electrical machines of the drive train with electrical energy for their operation. Alternatively or additionally, during recuperation, electrical energy from respective electrical machines can be fed into the energy storage device. The drive train can have an inverter as a control device, which can control a power transmission between the energy storage device and an electrical machine. The inverter can control the operation of an electrical machine.One inverter can be provided for each electrical machine. Alternatively, one inverter can be provided for several electrical machines.

[0013] The drive train is designed for continuously variable transmission between a crankshaft of the drive train and an output shaft of the drive train. For example, this can allow torque and, alternatively or additionally, a speed to be transmitted from the respective input shafts to the output shaft with an adjustable transmission ratio. The drive train can, for example, be designed for continuously variable transmission of torque between the crankshaft and the output shaft. A continuously variable transmission can mean that a transmission ratio can be freely selected, at least within a certain transmission range. This allows the transmission to be adapted particularly well to a current driving situation with few parts and little installation space required. In contrast, with a stepped transmission, for example, only discrete transmission ratios can be selected.For many different gear ratios, many parts are usually required, many of which are designed as switching elements, which require a correspondingly large amount of installation space.

[0014] The drivetrain has a transmission. The transmission can be designed for torque transmission from the crankshaft to the output shaft and alternatively or additionally from the first engine shaft to the output shaft. The transmission can enable continuously variable transmission. The transmission can be free of actively switchable clutches. The drivetrain can have only freewheels as switching elements, for example. The transmission ratio is varied, for example, only by a speed change on the first engine shaft.

[0015] The transmission has a first planetary gear set with a first sun gear, a first planet carrier, and a first ring gear. The transmission has a second planetary gear set with a second sun gear, a second planet carrier, and a second ring gear. The transmission has a third planetary gear set with a third sun gear, a third planet carrier, and a third ring gear. The transmission can, for example, be free of further planetary gear sets. The numbering of the rotating elements can merely serve to assign them to the respective planetary gear set. The second planetary gear set can, for example, be free of further rotating elements, such as, for example, a further sun gear or a further ring gear.

[0016] A planetary gear set can, for example, be designed as a minus planetary gear set or as a plus planetary gear set. A planetary gear set can have three rotating elements: a sun gear, a planet carrier, and a ring gear. One or more planet gears can be rotatably mounted on a planet carrier of a planetary gear set. For example, a planetary gear set can have three planet gears arranged on the same diameter around the crankshaft. A sun gear can have external teeth with which respective planet gears mesh. A ring gear can have internal teeth with which respective planet gears also mesh. In a minus planetary gear set, the planet gears mesh with both the sun gear and the ring gear, for example. A minus planetary gear set has a negative stationary gear ratio. Alternatively, a planetary gear set can be designed as a plus planetary gear set.A positive planetary gear set has a positive stationary ratio. For example, a positive planetary gear set has multiple sets of planetary gears. In the case of two sets of planetary gears, each planetary gear of a first set meshes with a sun gear and a planetary gear of a second set. In this case, the planetary gears of the second set mesh with the planetary gears of the first set and with a ring gear.

[0017] The first motor shaft is permanently connected to the first sun gear in a rotationally fixed manner. The first sun gear can form an input shaft of the transmission, on which a transmission ratio of the transmission can be adjusted by means of the first electric machine. The first planet carrier is permanently connected to the second ring gear in a rotationally fixed manner. The first planet carrier can be connected to the third sun gear in a rotationally fixed manner, for example by means of a freewheel. The first planet carrier can also be permanently connected to the third sun gear in a rotationally fixed manner. The first ring gear is permanently connected to the second sun gear. The third planet carrier can be connected to the crankshaft in a rotationally fixed manner, for example by means of a freewheel. The third planet carrier can also be permanently connected to the crankshaft in a rotationally fixed manner. The third planet carrier can thus form an input shaft of the transmission for introducing muscle power.The third ring gear can be connected to the output shaft in a rotationally fixed manner, for example, via a freewheel. The third ring gear can also be permanently connected to the output shaft in a rotationally fixed manner. The third ring gear can form an output shaft of the transmission, providing a geared variable for the output shaft. This results in a transmission with a compact design, continuously variable transmission with a wide gear ratio spread, and a small number of parts. The transmission can thus also be free of actively operated shifting elements.

[0018] If two elements are mechanically operatively connected, they can be directly or indirectly coupled to one another in such a way that a movement of one element can cause a reaction in the other element. For example, a mechanical operative connection can be provided by a positive or frictional connection. A mechanical operative connection can be established and also separated by a freewheel or another switching element. A mechanical operative connection, on the other hand, can exist permanently. For example, the mechanical operative connection can correspond to the meshing of corresponding teeth of two elements. Between mechanically

[0019] Additional elements may be provided for functionally connected elements.

[0020] A permanently non-rotatable connection between two elements is defined as a connection in which the two elements are essentially rigidly coupled to one another under all intended conditions. This also includes a frictional connection, in which intentional or unintentional slippage can occur. Permanently non-rotatably connected elements can, for example, be present as individual components connected to one another in a rotationally fixed manner or as a single piece.

[0021] A connection between two elements via a further element can mean that this further element can be involved in an indirect operative connection between the two elements. For example, this element can be arranged in the power flow between these two elements. A connection between two elements via two or more elements can mean that these further elements are all involved in an indirect operative connection between the two elements. A switchable connection can enable torque transmission between two elements in one state, for example through a rigid coupling, and essentially interrupt this torque transmission in another state. For this purpose, a corresponding switching element can be provided between the two elements.

[0022] The drivetrain may be free of any elements other than those listed here. For example, the drivetrain may not include any additional rotating elements, shifting elements, planetary gear sets, or, alternatively or additionally, electrical machines.

[0023] The second planetary gear set is nested radially outward with the first planetary gear set. The second planetary gear set can be arranged radially outward with respect to the first planetary gear set. Thus, at least one rotating element of the first planetary gear set can be arranged at least partially in the same axial region as a rotating element of the second planetary gear set. For example, at least the first ring gear and the second sun gear can be arranged at least partially in the same axial region. An axial region can, for example, correspond to an extension along the crankshaft. Due to the radially outward nesting with the first planetary gear set, all rotating elements of the second planetary gear set can be arranged radially outward with respect to all rotating elements of the first planetary gear set.For example, due to the radially outer nesting, all of the rotating elements of the second planetary gear set can each have an effective diameter that is larger than all of the effective diameters of all of the rotating elements of the first planetary gear set. For example, an effective diameter of an internal toothing of the first ring gear can be smaller than an effective diameter of an external toothing of the second sun gear. Due to the radial nesting, the transmission can be very compact axially, so that a high continuously variable transmission can be achieved even in the limited space of a bicycle frame. Due to the radial nesting, the planet gears of the first planetary gear set and the planet gears of the second planetary gear set can be relatively small and their toothings can have a comparatively small module, for example due to small teeth.Such a design is nevertheless possible without overloading the transmission, since any high torque potentially introduced by the driver at the crankshaft is significantly reduced by the third planetary gear set. This allows for minimal loading on the first and second planetary gear sets.

[0024] The planet gears of the first planetary gear set and the planet gears of the second planetary gear set can have essentially the same effective diameter. For this purpose, a corresponding stationary gear ratio can be selected for the first planetary gear set and the second planetary gear set. This can prevent a situation in which a large effective diameter of the planet gears of one of these two planetary gear sets would result in a small effective diameter of the planet gears of the other of these two planetary gear sets due to radial space limitations. Such space limitations can require very small planetary bearings. Without this space limitation, however, larger planetary bearings can be used, which can result in a long bearing service life.

[0025] In one embodiment of the drive train, it is provided that the first ring gear and the second sun gear are formed by a common component. This allows the drive train to be very compact, robust, and cost-effective. For example, this component can be formed integrally with external gearing and internal gearing. For example, this component can also be formed from multiple parts. By forming them as a common component, separate bearings for the first ring gear and the second sun gear can be omitted. Instead, they can be mounted together, for example.

[0026] In one embodiment of the drive train, the second planetary carrier is fixed. A fixed component is, for example, non-rotatable. For example, the second planetary carrier can be permanently connected in a rotationally fixed manner to a stationary component, such as a transmission housing. The housing can, for example, be formed by the bicycle frame or be permanently connected to it in a rotationally fixed manner. This design enables a high maximum speed. Furthermore, in most applications, such as not only very low driving speeds, rolling power can be low and efficiency high. The second planetary carrier can, for example, be permanently connected in a rotationally fixed manner to the housing axially on the motor side. In this case, the connection between the first planetary carrier and the second ring gear can, for example, be arranged axially on the output side of the first planetary gear set and the second planetary gear set.The second planetary carrier can, for example, be permanently connected to the housing axially on the output side in a rotationally fixed manner. The connection between the first planetary carrier and the second ring gear can then be arranged axially on the motor side, for example, to the first planetary gear set and the second planetary gear set. On the motor side, a side facing the first electric machine can be provided. On the output side, a side facing the output shaft can be provided.

[0027] In one embodiment of the drive train, it is provided that the second planet carrier is permanently connected to the third ring gear in a rotationally fixed manner. This allows a bearing base for the output shaft and, alternatively or additionally, the third ring gear to be particularly wide. This means that particularly heavy loads can be supported securely there. In this design, the connection between the first planet carrier and the second ring gear is arranged, for example, axially on the motor side to the first planetary gear set and the second planetary gear set. In one embodiment of the drive train, it is provided that the drive train has a second electric machine with a second motor shaft. The numbering of the second motor shaft can again serve to assign it to the second electric machine, which can be free of further motor shafts. The drive train can have a connecting gear with an input shaft and an output shaft.The connecting gear can be a transmission that connects the second motor shaft to the previously described transmission with a fixed or variable gear ratio. The connecting gear can, for example, be free of switching elements. The connecting gear can provide a mechanical connection between its input shaft and output shaft. The second motor shaft can be permanently connected to the input shaft in a rotationally fixed manner. The output shaft can be mechanically connected to the output shaft or permanently connected to the output shaft in a rotationally fixed manner. The second electric machine can provide particularly efficient support to the rider when driving the bicycle, for example by introducing motor drive force from the second electric machine on the input or output side. The second electric machine can also be efficiently driven as a generator.The connecting gear can facilitate a favorable arrangement of the second electric machine. The second electric machine can, for example, be arranged at least partially in the same axial region as the first electric machine. The second electric machine can be arranged radially outwardly of the first electric machine. The first motor shaft and the second motor shaft can be arranged parallel and offset from one another. The first motor shaft and the crank shaft can be arranged coaxially.

[0028] In one embodiment of the drive train, it is provided that the output shaft is rotatably connected to the output shaft. For example, the output shaft can be permanently rotatably connected to the output shaft or even formed by the output shaft or the third ring gear. The second electric machine can thus be connected to the output side. This can result in a design in which bearings for the third ring gear and, alternatively or additionally, the output shaft are particularly simple. In one embodiment of the drive train, it is provided that the output shaft is rotatably connected to the third planet carrier. For example, the output shaft can be permanently rotatably connected to the third planet carrier or even formed by the third planet carrier. The second electric machine can thus be connected to the drive side.This design could result in a particularly high support torque when starting from a standstill. Furthermore, the drive force of the second electric motor can be transmitted to the crankshaft together with the driver's muscle power.

[0029] In one embodiment of the drive train, it is provided that the connecting gear has a fourth planetary gear set with a fourth sun gear, a fourth planet carrier and a fourth ring gear. The numbering as a fourth planetary gear set can serve for assignment within the drive train. The connecting gear can, for example, be free of any planetary gear sets other than the fourth. However, the connecting gear can also have additional planetary gear sets or even provide different, switchable gear ratios. The connecting gear can also have a transmission gear. The planetary gear set allows the connecting gear to have a high gear ratio while requiring little installation space. The transmission gear can easily bridge an axial offset between the second electric machine and the rest of the drive train.

[0030] The fourth sun gear can be permanently connected to the second motor shaft in a rotationally fixed manner. The fourth sun gear can form an input of the connecting gear and the planetary gear set. The fourth planet carrier can be mechanically connected to the output shaft of the connecting gear via the transmission gear. The fourth planet carrier can form an output of the planetary gear set. The fourth ring gear can be fixed, for example, to the stationary component. The connecting gear can thus be cost-effective, compact, and efficient. The fourth planetary gear set can be arranged coaxially with the second electric machine. The transmission gear can be designed as a spur gear, for example with two spur gear stages. The transmission gear can, for example, have three spur gears that mesh with each other in pairs. Alternatively or additionally, the transmission gear can, for example, have a chain drive for the transmission.A chain drive, for example, can be quieter than a transmission with spur gear stages. Furthermore, bearing loads on the third hollow shaft and, alternatively or additionally, the output shaft can be low. Using spur gears for the transmission can reduce weight and make the drive train cost-effective.

[0031] In one embodiment of the drive train, it is provided that the drive train has a first freewheel. A freewheel can, for example, be designed as a pawl freewheel or roller freewheel. Two elements connected to the freewheel can be connected to one another in a rotationally fixed manner via a freewheel when the freewheel is in a locked state. In a released state, however, the two elements connected to the freewheel can be decoupled from one another. The freewheel can, for example, automatically switch between its locked state and its released state depending on a relative direction of rotation of the two elements connected to the freewheel. In the released state, no significant torque or speed transmission can take place between the elements connectable via the freewheel. In the locked state, torque and speed transmission can take place between the elements connected via the freewheel.By initially rotating the two elements relative to each other in a first relative direction, a freewheel can connect them in a rotationally fixed manner, thus achieving the locked state. Once the locked state is reached, no relative rotation between the two elements in the first relative direction is possible. In a second, opposite relative direction, however, these two elements can be decoupled from each other by the freewheel. In this way, the freewheel can be transferred from the locked state to the released state.

[0032] The crankshaft can be mechanically connected to the output shaft by means of the first freewheel. This allows the crankshaft to be decoupled from the output shaft. This prevents the crankshaft from being driven due to the inertia of the respective electric motors when the rider suddenly stops pedaling. This makes using the drivetrain particularly comfortable. Decoupling by the first freewheel can be particularly useful due to the high inertia and the high speed of the first electric motor and optional additional electric motors, such as the second electric motor, in the drivetrain, which is dependent on the transmission.

[0033] In one embodiment of the drive train, it is provided that the crankshaft is rotatably connected to the third planet carrier by means of the first freewheel. This means that only the crankshaft can be directly decoupled. This means that the mass inertia of the first electric machine and optionally also of the second electric machine, if present, can be decoupled, for example, from the crankshaft. In this design, the third ring gear can be permanently rotatably connected to the output shaft and the first planet carrier can be permanently rotatably connected to the third sun gear. With this design, integration of the freewheel is particularly simple. In addition, the drive train can be particularly short axially. Furthermore, a differential speed at the first freewheel can be particularly low in the open state. Alternatively, instead of the first freewheel, a permanent rotatably connected connection of the third planet carrier to the crankshaft can be provided.

[0034] In one embodiment of the drive train, the third ring gear is rotatably connected to the output shaft by means of the first freewheel. This allows the output shaft to be decoupled from the rest of the drive train. With this design, the crankshaft can be permanently connected to the third planet carrier in a rotationally fixed manner, and the first planet carrier can be permanently connected to the third sun gear in a rotationally fixed manner. Alternatively, instead of the first freewheel, a permanent rotationally fixed connection of the third ring gear to the output shaft can also be provided.

[0035] In one embodiment of the drive train, it is provided that the first planet carrier can be connected in a rotationally fixed manner to the third sun gear by means of the first freewheel. This means that torque transmission from the crankshaft to the output shaft can also be interrupted by an interruption in torque transmission at the third planetary gear set. With this design, the first freewheel must, for example, transmit a particularly low torque in the locked state. This means that the first freewheel can be particularly small and light. With this design, the crankshaft can be permanently connected in a rotationally fixed manner to the third planet carrier and the third ring gear can be permanently connected in a rotationally fixed manner to the output shaft. Alternatively, instead of the first freewheel, the first planet carrier can be permanently connected in a rotationally fixed manner to the third sun gear.

[0036] In one embodiment of the drive train, the drive train is provided with a second freewheel. The second freewheel can be designed to block rotation of the first motor shaft in one direction of rotation. For example, the second freewheel can only allow rotation of the motor shaft in one direction of rotation, which serves to reduce a gear ratio of the transmission. In this way, heavy loads can be supported safely, for example when the rider's full weight acts on a pedal. For example, this can also be used to support a starting torque from the rider that the first electric machine cannot support. Furthermore, even if the power supply to the first electric machine fails, the bicycle can be started off without any problems. If no second freewheel is provided, a comparatively high gear ratio can be provided for particularly easy starting off.

[0037] In one embodiment of the drive train, the first motor shaft can be secured by means of the second freewheel, for example, to the stationary component. This allows a particularly small torque to act on the second freewheel, since the pedal force is previously transmitted to the crankshaft by the transmission.

[0038] In one embodiment of the drive train, it is provided that a rotating element of the first planetary gear set can be fixed by means of the second freewheel.

[0039] For example, the first planet carrier can be locked by means of the second freewheel. Alternatively, for example, the first ring gear can be locked by means of the second freewheel. In these designs, for example, the second planet carrier is locked. The second freewheel can thus be easily integrated. A second aspect relates to a bicycle. The bicycle can be designed, for example, as a pedelec. The bicycle can have a drive train according to the first aspect. Respective features and advantages of the first aspect accordingly equally represent features and advantages of the second aspect and vice versa. The bicycle can have a bicycle frame and at least one wheel. The output shaft of the drive train can be mechanically operatively connected to the at least one wheel of the bicycle, for example by means of a chain or a belt. The wheel can thus be a driven wheel.The wheel may, for example, have a rim and a casing. The wheel may also have a hub. The hub may have an additional freewheel.

[0040] Short description of the characters

[0041] Fig. 1 shows schematically a first embodiment of a drive train of a bicycle.

[0042] Fig. 2 shows schematically a second embodiment of the drive train.

[0043] Fig. 3 shows schematically a third embodiment of the drive train.

[0044] Fig. 4 shows schematically a fourth embodiment of the drive train.

[0045] Fig. 5 shows schematically a fifth embodiment of the drive train.

[0046] Fig. 6 shows schematically a sixth embodiment of the drive train.

[0047] Fig. 7 shows schematically a seventh embodiment of the drive train.

[0048] Fig. 8 shows schematically an eighth embodiment of the drive train.

[0049] Fig. 9 shows schematically a ninth embodiment of the drive train.

[0050] Fig. 10 schematically shows a tenth embodiment of the drive train. Fig. 11 schematically shows an eleventh embodiment of the drive train.

[0051] Detailed description of embodiments

[0052] Fig. 1 schematically shows a first embodiment of a drive train for a bicycle with a crankshaft 10, an output shaft 12, a transmission 14, and a first electric machine EM1 with a first motor shaft W1. The drive train is designed for a continuously variable transmission between the crankshaft 10 and the output shaft 12. The crankshaft 10 defines an axial direction and extends as a central shaft through the transmission 14. The first motor shaft W1 is arranged coaxially to the crankshaft 10.

[0053] The transmission 14 has a first planetary gear set 20 with a first sun gear 22, a first planet carrier 24, and a first ring gear 26. A set of first planet gears 28 is rotatably mounted on the first planet carrier 24, each of which meshes with the first sun gear 22 and the first ring gear 26. The transmission 14 has a second planetary gear set 30 with a second sun gear 32, a second planet carrier 34, and a second ring gear 36. A set of second planet gears 38 is rotatably mounted on the second planet carrier 34, each of which meshes with the second sun gear 32 and the second ring gear 36. The transmission 14 has a third planetary gear set 40 with a third sun gear 42, a third planet carrier 44, and a third ring gear 46. A set of third planetary gears 48 is rotatably mounted on the third planet carrier 44, which mesh with the third sun gear 42 and the third ring gear 46, respectively.By means of the first electric machine EM1, a gear ratio from the crankshaft 10 via the third planetary gear set 40 to the output shaft 12 can be continuously changed.

[0054] The second planetary gear set 30 is nested radially on the outside with the first planetary gear set 20. All effective diameters of the rotating elements of the second planetary gear set 30 are larger than all effective diameters of the rotating elements of the first planetary gear set 20. In contrast, the effective diameters of the planet gears 38 of the second planetary gear set 30 are, depending on the design, smaller, equal to, or larger than the respective effective diameters of the planet gears 28 of the first planetary gear set 20. Furthermore, the second planetary gear set 30 is arranged at least partially axially in the same area as the first planetary gear set 20. The drive train is therefore particularly short axially. The third planetary gear set 40 is arranged axially next to the first planetary gear set 20 and the second planetary gear set 30. In the example shown, the third planetary gear set 40 extends radially in overlap with the second planetary gear set 30 and the first planetary gear set 20.The three planetary gear sets 20, 30 and 40 are arranged coaxially with the crankshaft 10.

[0055] The first motor shaft W1 is permanently connected to the first sun gear 22 in a rotationally fixed manner. The first planet carrier 24 is permanently connected to the second ring gear 36 in a rotationally fixed manner. The first planet carrier 24 is rotationally fixedly connected to the third sun gear 42. The first ring gear 26 is permanently connected to the second sun gear 32 in a rotationally fixed manner. The first ring gear 26 and the second sun gear 32 are formed by a common component, which in the example shown is designed as a one-piece element with internal gearing and external gearing. The third planet carrier 44 is rotationally fixedly connected to the crankshaft 10. The third ring gear 46 is rotationally fixedly connected to the output shaft 12.

[0056] The crankshaft 10 is mechanically operatively connected to the output shaft 12 by means of an optional first freewheel F1. In the first embodiment, the third planet carrier 44 is rotationally connectable to the crankshaft 10 by means of the first freewheel F1. In the first embodiment, the first planet carrier 24 and the third sun gear 42 are permanently rotationally connected to one another. In the first embodiment, the third ring gear 46 is permanently rotationally connected to the output shaft 12. The second planet carrier 34 is permanently rotationally connected to a stationary component 50 in the form of a housing and is thus fixed. The connection between the stationary component 50 and the second planet carrier 34 is arranged axially on the engine side relative to the first planetary gear set 20 and the second planetary gear set 30.The connection between the first planetary carrier 24 and the second ring gear 36 is arranged axially on the output side of the first planetary gear set 20 and the second planetary gear set 30. Fig. 2 shows a second embodiment of the drive train, which is similar to the first embodiment. Only differences from the first embodiment will be discussed below.

[0057] In the second embodiment, the second planet carrier 34 is permanently connected to the third ring gear 46 in a rotationally fixed manner, rather than being fixed. Accordingly, the connection between the first planet carrier 24 and the second ring gear 36 is now arranged axially on the motor side relative to the first planetary gear set 20 and the second planetary gear set 30. This design of the transmission 14 and the aforementioned connections can also be provided in the other embodiments, which are designed like the first embodiment in terms of these parts and connections.

[0058] Fig. 3 shows a third embodiment of the drive train, which additionally includes a second electric machine EM2 with a second motor shaft W2 and a connecting gear 60 with an input shaft and an output shaft, and is otherwise configured identically to the first embodiment. The second motor shaft W2 is permanently connected to the input shaft in a rotationally fixed manner. The output shaft is mechanically operatively connected to the output shaft 12.

[0059] For this connection, the connecting gear 60 has a fourth planetary gear set 70 with a fourth sun gear 72, a fourth planet carrier 74 and a fourth ring gear 76, as well as a transmission gear 62. A set of fourth planet gears 78 is rotatably mounted on the fourth planet carrier 74, each of which meshes with the fourth sun gear 72 and the fourth ring gear 76. The fourth sun gear 72 is permanently connected in a rotationally fixed manner to the second motor shaft W2 and thus forms the input shaft of the connecting gear 60. The fourth ring gear 76 is permanently connected in a rotationally fixed manner to the stationary component 50 and is thus fixed. The transmission gear 62 has three spur gears 64, 66 and 68, which mesh with one another in pairs. A spur gear 64 on the motor side in the torque flow is permanently connected in a rotationally fixed manner to the fourth planet carrier 74.A spur gear 68, located on the output side in the torque flow, is permanently connected to the output shaft 12 in a rotationally fixed manner or is formed by it. This spur gear 68, located on the output side, thus forms the output shaft of the.

[0060] Connecting gear 60.

[0061] This results in a connection of the second electric motor EM2 on the output side in the torque flow, which can thus directly drive the output shaft 12. The two motor shafts W1, W2 are arranged offset parallel to the axes. The transmission gear 62 bridges any axial offset. Alternatively or additionally, depending on the selected design and the effective diameters of spur gears or pinions, the transmission gear 62 provides a transmission ratio between the fourth planet carrier 74 and the output shaft 12. The fourth planetary gear set 70 provides a compact, high transmission ratio for the second electric motor EM2.

[0062] Fig. 4 shows a fourth embodiment of the drive train, which is similar to the third embodiment. Only differences from the third embodiment will be discussed below.

[0063] In the fourth embodiment, the second electric machine EM2 is connected to the rest of the drive train differently. The output shaft of the connecting gear 60, which is again formed by the most output-side spur gear 68 of the transmission gear 62, can be connected in a rotationally fixed manner to the third planet carrier 44 or is formed by the third planet carrier 44. In the fourth embodiment, the output shaft, in the example shown, is permanently connected in a rotationally fixed manner to the third planet carrier 44. The second electric machine EM2 is thus connected on the input side to the transmission 14. This allows a drive force provided by the second electric machine EM2 to be transmitted to the output shaft 12 with the continuously variable transmission ratio provided by the first electric machine EM1.In the fourth embodiment, the transmission gear 62 is arranged axially on the motor side relative to the third planetary gear set 40 instead of, as in the third embodiment, in the axially same area or axially on the output side.

[0064] Fig. 5 shows a fifth embodiment of the drive train, which is similar to the third embodiment. In the following, only differences from the third embodiment will be discussed. In the fifth embodiment, in contrast to the first and third embodiments, the second planet carrier 34 is axially connected to the stationary component 50 on the output side and thus between the first planetary gear set 20 or second planetary gear set 30 and the third planetary gear set 40. The connection of the second ring gear 36 to the first planet carrier 24 is axially on the motor side and arranged between the first electric machine EM1 and the first planetary gear set 20 or second planetary gear set 30.

[0065] Fig. 6 shows a sixth embodiment of the drive train, which is similar to the third embodiment. Only differences from the third embodiment will be discussed below.

[0066] In the sixth embodiment, the first freewheel F1 is arranged differently. The first planetary carrier 24 is rotationally fixed to the third sun gear 42 by means of the first freewheel F1. Thus, there is no permanent rotationally fixed connection between the first planetary carrier 24 and the third sun gear 42. However, the crankshaft 10 and the third planetary carrier 44 are now permanently rotationally fixed to one another. Furthermore, the third planetary gear set 40 is now positioned axially further toward the output side relative to the transmission gear 62 compared to the third embodiment.

[0067] Fig. 7 shows a seventh embodiment of the drive train, which is similar to the third embodiment. Only differences from the third embodiment will be discussed below.

[0068] In the seventh embodiment, the first freewheel F1 is arranged differently than in the third and sixth embodiments. By means of the first freewheel F1, the third ring gear 46 can be connected to the output shaft 12 in a rotationally fixed manner. There is therefore no permanent rotationally fixed connection between the third ring gear 46 and the output shaft 12. However, the crankshaft 10 and the third planet carrier 44 are now permanently connected to one another in a rotationally fixed manner. In contrast to the sixth embodiment, the first planet carrier 24 and the third sun gear 42 are now also permanently connected to one another in a rotationally fixed manner. Furthermore, the third planetary gear set 40 is now positioned axially further on the engine side relative to the transmission 62 compared to the third embodiment. The first freewheel F1 is thus arranged axially between the third planetary gear set 40 and the transmission 62.

[0069] Fig. 8 shows an eighth embodiment of the drive train, which is similar to the third embodiment. Only differences from the third embodiment will be discussed below.

[0070] In the eighth embodiment, the transmission gear 62 of the connecting gear 60 is designed differently. Instead of three spur gear stages, a chain drive 80 is now provided. A first pinion 82 of this chain drive 80 is arranged on the engine side in the torque flow and is permanently connected in a rotationally fixed manner to the fourth planet carrier 74. A second pinion 84 of this chain drive 80 is arranged on the output side in the torque flow and forms the output shaft of the connecting gear 60. The second pinion 84 is permanently connected in a rotationally fixed manner to the output shaft 12 or is formed by it.

[0071] Fig. 9 shows a ninth embodiment of the drive train, which additionally has a second freewheel F2 and is otherwise configured identically to the third embodiment. The second freewheel F2 is designed to block rotation of the first motor shaft W1 in one direction of rotation. In contrast, the first motor shaft W1 is released and can rotate in the opposite direction.

[0072] In the ninth embodiment, the first motor shaft W1 can be locked by means of the second freewheel F2. In the locked state, the second freewheel F2 connects the first motor shaft W1 to the stationary component 50 in a rotationally fixed manner. The second freewheel F2 is arranged such that rotation of the first motor shaft W1 by the first electric machine EM1 is only possible in one direction of rotation, which increases the gear ratio of the third planetary gear set 40 from the third planet carrier 44 to the third ring gear 46. Fig. 10 shows a tenth embodiment of the drive train and Fig. 11 shows an eleventh embodiment of the drive train. In these two embodiments, a rotating element of the first planetary gear set 20 can be locked by means of the second freewheel F2 in order to block rotation of the first motor shaft W1 in one direction of rotation, as in the ninth embodiment.In the tenth embodiment, the first planet carrier 24 is rotatably connected to the stationary component 50 by means of the second freewheel element F2 and can thus be locked. In the eleventh embodiment, the first ring gear 26 is rotatably connected to the stationary component 50 by means of the second freewheel element F2 and can thus be locked. Otherwise, the tenth embodiment and the eleventh embodiment are designed identically to the ninth embodiment.

[0073] Reference symbol

[0074] 10 Crankshaft

[0075] 12 Output shaft

[0076] 14 gearboxes

[0077] 20, 30, 40, 70 planetary gear set

[0078] 22, 32, 42, 72 sun gear

[0079] 24, 34, 44, 74 planet carriers

[0080] 26, 36, 46, 76 ring gear

[0081] 28, 38, 48, 78 planetary gears

[0082] 50 stationary component

[0083] 60 connecting gears

[0084] 62 transmission gears

[0085] 64, 66, 68 spur gear

[0086] 80 chain drive

[0087] 82, 84 pinion

[0088] EM1 ; EM2 electrical machine

[0089] W1, W2 motor shaft

[0090] F1; F2 freewheel

Claims

Patent claims 1 . A drive train for a bicycle with a crankshaft (10), an output shaft (12), a transmission (14), and a first electric machine (EM1) with a first motor shaft (W1), wherein the drive train is designed for a continuously variable transmission between the crankshaft (10) and the output shaft (12), wherein the transmission (14) has a first planetary gear set (20) with a first sun gear (22), a first planet carrier (24), and a first ring gear (26), a second planetary gear set (30) with a second sun gear (32), a second planet carrier (34), and a second ring gear (36), and a third planetary gear set (40) with a third sun gear (42), a third planet carrier (44), and a third ring gear (46), wherein the first motor shaft (W1) is permanently connected to the first sun gear (22) in a rotationally stable manner, wherein the first planet carrier (24) is permanently connected to the second ring gear (36),wherein the first planetary carrier (24) is rotationally connectable to the third sun gear (42), wherein the first ring gear (26) is permanently rotationally connected to the second sun gear (32), wherein the third planetary carrier (44) is rotationally connectable to the crankshaft (10), wherein the third ring gear (46) is rotationally connectable to the output shaft (12), wherein the second planetary gear set (30) is nested radially outwardly with the first planetary gear set (20).

2. Drive train according to claim 1, characterized in that the first ring gear (26) and the second sun gear (32) are formed by a common component.

3. Drive train according to claim 1 or 2, characterized in that the second planet carrier (34) is fixed.

4. Drive train according to claim 1 or 2, characterized in that the second planet carrier (34) is permanently connected to the third ring gear (46) in a rotationally fixed manner.

5. Drive train according to one of the preceding claims, characterized in that the drive train comprises a second electric machine (EM2) with a second motor shaft (W2) and a connecting gear (60) with an input shaft and an output shaft, wherein the second Motor shaft (W2) is permanently connected to the input shaft in a rotationally fixed manner and the output shaft is mechanically operatively connected to the output shaft (12).

6. Drive train according to claim 5, characterized in that the output shaft is rotatably connectable to the output shaft (12).

7. Drive train according to claim 5, characterized in that the output shaft is rotatably connectable to the third planet carrier (44).

8. Drive train according to one of claims 5 to 7, characterized in that the connecting gear (60) has a fourth planetary gear set (70) with a fourth sun gear (72), a fourth planet carrier (74) and a fourth ring gear (76) and a transmission gear (62), wherein the fourth sun gear (72) is permanently connected in a rotationally fixed manner to the second motor shaft (W2), wherein the fourth planet carrier (74) is mechanically operatively connected via the transmission gear (62) to the output shaft of the connecting gear (60) and wherein the fourth ring gear (76) is fixed.

9. Drive train according to one of the preceding claims, characterized in that the drive train has a first freewheel (F1), wherein the crank world (10) is mechanically operatively connected to the output world (12) by means of the first freewheel (F1), 10. Drive train according to claim 9, characterized in that the crankshaft (10) is rotatably connectable to the third planet carrier (44) by means of the first freewheel (F1) and the third ring gear (46) is permanently rotatably connected to the output shaft (12) and the first planet carrier (24) is permanently rotatably connected to the third sun gear (42).

11. Drive train according to claim 9, characterized in that the third ring gear (46) can be connected in a rotationally fixed manner to the output shaft (12) by means of the first freewheel (F1), the crankshaft (10) is permanently connected in a rotationally fixed manner to the third planet carrier (44) and the first planet carrier (24) is permanently connected in a rotationally fixed manner to the third sun gear (42).

12. Drive train according to claim 9, characterized in that the first planet carrier (24) is rotatably connected to the third sun gear (42) by means of the first freewheel (F1), the crankshaft (10) is permanently rotatably connected to the third planet carrier (44) and the third ring gear (46) is permanently rotatably connected to the output shaft (12).

13. Drive train according to one of the preceding claims, characterized in that the drive train has a second freewheel (F2), wherein the second freewheel (F2) is designed to block rotation of the first motor shaft (W1) in one direction of rotation.

14. Drive train according to claim 13, characterized in that the first motor shaft (W1) can be fixed by means of the second freewheel (F2).

15. Drive train according to claim 13, characterized in that a Rotating element of the first planetary gear set (20) can be fixed by means of the second freewheel (F2).

Images