Drive train for bicycle

Abstract

The invention relates to a drive train configured for continuously variable transmission between a crankshaft (10) and a driven shaft (12). The transmission (14) has three planetary gear sets (20, 30, 40). 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) can be connected to the third sun gear (42) in a rotationally fixed manner. The first ring gear (26) is permanently connected to the second sun gear (32) in a rotationally fixed manner. The third planet carrier (44) can be connected to the crankshaft (10) in a rotationally fixed manner. The third ring gear (46) can be connected to the output shaft (12) in a rotationally fixed manner. The second planetary gear set (30) is nested in the first planetary gear set (20) from the radial outer side.

Description

Technical Field

[0001] The present invention relates to a drive train for a bicycle. Background Art

[0002] In bicycles, the gear shifting mechanism is a crucial component for achieving comfortable riding in different gears. The more accurately the speed ratio in the bicycle's drivetrain can be adapted to the current riding speed, the more comfortable the rider can pedal at the crank speed. However, achieving such adaptability in speed ratios typically requires a complex transmission, requiring a large amount of space. When the transmission is installed in a bicycle frame, the space available is very limited. Similarly, to achieve both easy climbing and high riding speeds, a wide range of speed ratios is desirable.

[0003] Furthermore, modern bicycles often feature an electric powertrain. These bicycles are also known as electric assisted bicycles. This allows even people with limited physical fitness to ride the bicycle comfortably. When using an electric motor for powertrain support, it is also desirable to have a compatible speed ratio to efficiently operate the electric powertrain.

[0004] DE 10 2015 208 355 A1 describes a vehicle having a transmission of planetary design, wherein the transmission is particularly suitable for electric vehicles due to its design. Summary of the Invention

[0005] A first aspect relates to a drive train for a bicycle. The bicycle can be configured, for example, as a muscle-powered vehicle or as an electric power-assisted bicycle. At least a portion of the driving force can be provided, for example, by the rider. The bicycle, for example, has a bicycle frame and at least two running wheels rotatably fastened to the bicycle frame. The drive train can be configured to provide driving force to at least one of the driven running wheels.

[0006] The drive train includes a crankshaft. A crank arm can be fastened to the crankshaft, and pedals can be rotatably fastened to the crank arm. The rider of the vehicle can apply muscle force to the crankshaft via the pedals (e.g., using the rider's legs). The muscle force can be introduced into the drive train via the crankshaft. The crankshaft can, for example, be configured as a central axis extending transversely through the bicycle frame. The crankshaft and, optionally, the entire drive train can be supported in the center axle region of the bicycle frame.

[0007] The drive train includes a driven shaft. The driven shaft can be connected to the vehicle's wheels via a power transmission element. For example, the driven shaft can be connected to the vehicle's wheels via a chain or belt. For example, a pinion can be permanently secured to the driven shaft in a rotationally fixed manner. The driven shaft can be arranged coaxially with the crankshaft, for example.

[0008] The drive train comprises a first electric motor with a first motor shaft. In addition to the first electric motor, the drive train may also have further electric motors. Alternatively, the drive train may not have an additional electric motor. The first electric motor may be designed to provide drive power to the first motor shaft. The numbering of the first motor shaft may be used solely for the assignment to the first electric motor. Therefore, the first electric motor may not contain further motor shafts. The first electric motor can, for example, change the speed ratio from the crankshaft to the driven shaft by rotating the first motor shaft. Alternatively or additionally, drive power can also be provided to the driven shaft, for example.

[0009] The electric motor can be configured to convert electrical energy into mechanical energy. Alternatively or additionally, the electric motor can be configured for regeneration. The electric motor can be configured, for example, as an asynchronous motor or a synchronous motor. The drive train can have an energy storage device, such as a battery. For example, the energy storage device can provide electrical energy to the individual electric motors of the drive train to operate the electric motors. Alternatively or additionally, during regeneration, the electrical energy from the individual electric motors can be fed into the energy storage device. The drive train can have an inverter as a control device, which can control the power transmission between the energy storage device and the electric motor. The inverter can control the operation of the electric motor. An inverter can be provided for each electric motor. Alternatively, an inverter can be provided for multiple electric motors.

[0010] The drive train is designed for continuously variable transmission between the crankshaft and the driven shaft of the drive train. For example, this allows the transmission of torque and, alternatively or additionally, rotational speed from the respective input shaft to the driven 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 driven shaft. Continuously variable transmission can mean that the transmission ratio can be freely selected, at least within a specific ratio range. This allows the transmission to be particularly well adapted to the current riding situation with fewer parts and a low space requirement. In contrast, for example, in a stepped transmission, only discrete transmission ratios can be selected. In order to achieve a variety of different speed ratios, a large number of parts are usually required, many of which are designed as shifting elements and accordingly require a large space requirement.

[0011] The drive train includes a transmission. The transmission can be configured to transmit torque from the crankshaft to the driven shaft, or alternatively or additionally, to transmit torque from the first motor shaft to the driven shaft. The transmission enables continuously variable transmission. The transmission may not include an actively shiftable clutch. For example, the drive train may only include a freewheel mechanism as a shifting element. The speed ratio is changed, for example, solely by changes in the rotational speed of the first motor shaft.

[0012] The transmission comprises a first planetary gear set having a first sun gear, a first planetary carrier, and a first ring gear. The transmission comprises a second planetary gear set having a second sun gear, a second planetary carrier, and a second ring gear. The transmission comprises a third planetary gear set having a third sun gear, a third planetary carrier, and a third ring gear. The transmission may, for example, not contain any additional planetary gear sets. The numbering of the rotating elements is used solely to assign them to their respective planetary gear sets. For example, the second planetary gear set may not contain any additional rotating elements, such as additional sun gears or additional ring gears.

[0013] A planetary gear set can be configured as either a negative planetary gear set or a positive 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 supported on the planet carrier of the planetary gear set. For example, the planetary gear set can have three planet gears arranged on the same diameter around the crankshaft. The sun gear can have an external toothing, with each planet gear meshing with the external toothing. The ring gear can have an internal toothing, with each planet gear also meshing with the internal toothing. In a negative planetary gear set, for example, the planet gears mesh not only with the sun gear but also with the ring gear. A negative planetary gear set has a negative fixed-axis speed ratio. Alternatively, the planetary gear set can be configured as a positive planetary gear set. A positive planetary gear set has a positive fixed-axis speed ratio. In a positive planetary gear set, for example, multiple sets of planet gears are provided. When two sets of planet gears are used, each planet gear in the first set meshes with both the sun gear and the planet gear in the second set. In this case, the planet gears in the second set mesh with both the first set of planet gears and the ring gear.

[0014] The first motor shaft is permanently connected to the first sun gear in a rotationally fixed manner. The first sun gear can form the input shaft of the transmission, on which the speed ratio of the transmission can be adjusted using the first electric machine. The first planet carrier is permanently connected to the second ring gear. The first planet carrier can be permanently connected to the third sun gear in a rotationally fixed manner, for example, via a freewheel mechanism. The first planet carrier can also be permanently connected to the third sun gear in a rotationally fixed manner. The first ring gear can also be permanently connected to the second sun gear in a rotationally fixed manner. The third planet carrier can be rotationally fixed to the crankshaft, for example, via a freewheel mechanism. The third planet carrier can also be rotationally fixed to the crankshaft. Thus, the third planet carrier can form the input shaft of the transmission for introducing muscular force. The third ring gear can be rotationally fixed to the driven shaft, for example, via a freewheel mechanism. The third ring gear can also be rotationally fixed to the driven shaft. The third ring gear can form the output shaft of the transmission, on which the variable speed is supplied to the driven shaft. This results in a transmission with a compact design, a continuously adjustable speed ratio over a wide range, and a small number of parts. The transmission can therefore also contain no shifting elements to be actively actuated.

[0015] If two elements are mechanically operatively connected, they can be coupled to one another directly or indirectly in such a way that a movement of one element can cause a reaction in the other. For example, the mechanical operative connection can be provided by a form-locking or friction-locking connection. Mechanically operative connection can be established and disconnected by a freewheel mechanism or other switching element. Conversely, a mechanical operative connection can be continuous. For example, the mechanical operative connection can be equivalent to the meshing of corresponding teeth of the two elements. Additional elements can be arranged between the mechanically operatively connected elements.

[0016] A permanently rotationally fixed connection of two elements is a connection in which the two elements are essentially rigidly coupled to one another in all intended states. This also includes frictional connections in which slippage, whether intentional or unintentional, can occur. Elements that are permanently rotationally fixed can be present, for example, as individual components that are rotationally fixedly connected to one another or as a single piece.

[0017] The connection of two elements via another element can mean that the other element participates in the indirect operative connection of the two elements. For example, the element can be arranged in the power flow between the two elements. The connection of two elements via two or more elements can mean that these other elements all participate in the indirect operative connection of the two elements. A switchable connection can enable torque transmission between the two elements in one state (for example, via a rigid coupling) and substantially interrupt this torque transmission in another state. To this end, a corresponding switching element can be provided between the two elements.

[0018] The drive train may not contain any further elements other than those mentioned herein. For example, the drive train may not have any further rotating elements, switching elements, planetary gear sets, or alternative or additional electric machines.

[0019] The second planetary gear set is nested radially outside the first planetary gear set. The second planetary gear set can be arranged radially outward relative to the first planetary gear set. Consequently, at least one rotating element of the first planetary gear set can be at least partially arranged within 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 at least partially arranged within the same axial region. The axial region can, for example, correspond to the extent along the crankshaft. Because the first planetary gear set is nested radially outside, all rotating elements of the second planetary gear set can be arranged radially outward relative to all rotating elements of the first planetary gear set. For example, due to the radially outward nesting, all rotating elements of the second planetary gear set can have an effective diameter that is larger than the effective diameter of all rotating elements of the first planetary gear set. For example, the effective diameter of the inner teeth of the first ring gear can be smaller than the effective diameter of the outer teeth of the second sun gear. This radial nesting allows the transmission to be very compact axially, thus achieving a high continuously variable transmission even with limited space in a bicycle frame. This radial nesting allows the planetary gears of the first and second planetary gear sets to be relatively small, and, for example, due to a smaller number of teeth, their toothing can have a relatively small module. However, this design still does not overload the transmission, because any high torques introduced by the rider at the crankshaft are significantly reduced by the third planetary gear set. This allows the first and second planetary gear sets to be less loaded.

[0020] The planetary gears of the first planetary gear set and the planetary gears of the second planetary gear set can have substantially the same effective diameter. To this end, corresponding fixed-axis speed ratios can be selected for the first and second planetary gear sets. This avoids radial space limitations that result in the planetary gears of one planetary gear set having a larger effective diameter while the planetary gears of the other planetary gear set have a smaller effective diameter. Such space limitations may require very small planetary bearings. Conversely, if such space limitations are eliminated, larger planetary bearings can be used, thereby increasing the bearing's service life.

[0021] In one embodiment of the drive train, the first ring gear and the second sun gear are formed from a common component. This makes the drive train very compact, robust, and inexpensive. For example, the component can be constructed integrally with the external and internal gearing. Alternatively, the component can be formed from multiple parts. The common component configuration eliminates the need for separate supports for the first ring gear and the second sun gear. Instead, they can be supported together, for example.

[0022] In one embodiment of the drive train, the second planet carrier is stationary. A stationary component, for example, cannot rotate. For example, the second planet carrier can be permanently connected to a stationary component, such as the transmission housing, in a rotationally fixed manner. The housing can, for example, be formed by the bicycle frame or be permanently connected to it in a rotationally fixed manner. This design allows for a high maximum speed. Furthermore, in most applications, not just at very low riding speeds, rolling power can be kept low and efficiency high. The second planet carrier can, for example, be axially connected to the housing in a rotationally fixed manner on the motor side. Thus, the connection between the first planet carrier and the second ring gear can, for example, be arranged axially on the output side relative to the first and second planetary gear sets. The second planet carrier can, for example, be axially connected to the housing in a rotationally fixed manner on the output side. Thus, the connection between the first planet carrier and the second ring gear can, for example, be axially arranged on the motor side relative to the first and second planetary gear sets. The motor side can be the side facing the first electric motor. The output side can be the side facing the driven shaft.

[0023] One embodiment of the drive train provides for a permanent, rotationally fixed connection between the second planet carrier and the third ring gear. This allows the bearing seat for the driven shaft and, alternatively or additionally, the third ring gear to be particularly wide. This allows particularly high loads to be reliably supported there. In this design, the connection between the first planet carrier and the second ring gear can be arranged axially on the motor side relative to the first and second planetary gear sets, for example.

[0024] One embodiment of the drive train provides a second electric motor with a second motor shaft. The number of the second motor shaft can be used to assign it to the second electric motor, which may not include a separate motor shaft. The drive train may include a connecting transmission with an input shaft and an output shaft. The connecting transmission may be a transmission that connects the second motor shaft to the aforementioned transmission with a fixed or variable speed ratio. The connecting transmission may, for example, not include a shifting element. The connecting transmission may provide a mechanical operative connection between its input shaft and output shaft. The second motor shaft may be permanently rotationally fixedly connected to the input shaft. The output shaft may be mechanically operatively connected or permanently rotationally fixedly connected to the output shaft. The second electric motor can provide particularly efficient assistance to the rider when driving the bicycle, for example by introducing motor-like driving force from the second electric motor on the input or output side. The second electric motor can also be driven efficiently as a generator. The connecting transmission facilitates advantageous arrangement of the second electric motor. For example, the second electric motor may be arranged at least partially in the same axial region as the first electric motor. The second electric motor may be arranged radially outward of the first electric motor. The first motor shaft and the second motor shaft may be arranged in parallel and offset from each other.The first motor shaft and the crank shaft may be arranged coaxially.

[0025] One embodiment of the drive train provides for the output shaft to be rotationally fixedly connected to the driven shaft. For example, the output shaft can be permanently rotationally fixedly connected to the driven shaft or even formed by the driven shaft or the third ring gear. Thus, the second electric motor can be connected to the driven shaft. This results in a particularly simple design in which the third ring gear and, alternatively or additionally, the driven shaft are supported.

[0026] In one embodiment of the drive train, the output shaft is configured to be rotationally fixedly connected to the third planetary carrier. For example, the output shaft can be permanently rotationally fixedly connected to the third planetary carrier, or even formed by the third planetary carrier. Thus, the second electric motor can be connected to the drive side. This allows for a particularly high support torque when starting from a standstill. Furthermore, the driving force of the second electric motor can be used together with the rider's muscle power to transmit the speed change to the crankshaft.

[0027] In one embodiment of the drive train, it is provided that the connecting transmission has a fourth planetary gear set with a fourth sun gear, a fourth planetary carrier, and a fourth ring gear. The number of the fourth planetary gear set can be used for assignment within the drive train. The connecting transmission may, for example, not contain any other planetary gear sets besides the fourth planetary gear set. However, the connecting transmission may also contain other planetary gear sets or even provide different switchable speed ratios. The connecting transmission may also have a transfer transmission. The planetary gear sets allow the connecting transmission to have a very high speed ratio while requiring little structural space. The transfer transmission can easily compensate for the axial offset of the second electric machine from the rest of the drive train.

[0028] The fourth sun gear can be permanently connected to the second motor shaft in a rotationally fixed manner. The fourth sun gear can form the input of the connecting gear and the planetary gear set. The fourth planet carrier can be mechanically operatively connected to the output shaft of the connecting gear via the transfer gear. The fourth planet carrier can form the output of the planetary gear set. The fourth ring gear can be stationary, for example, on a stationary component. This makes the connecting gear cost-effective, compact, and efficient. The fourth planetary gear set can be arranged coaxially with the second electric motor. The transfer gear can be configured, for example, as a spur gear transmission with two spur gear stages. The transfer gear can, for example, have three spur gears that mesh with each other in pairs. Alternatively or additionally, the transfer gear can utilize a chain drive for transmission. A chain drive can be quieter than a transfer gear with spur gear stages. Furthermore, bearing loads on the third hollow shaft and the alternative or additional output shaft can be reduced. Using spur gears for the transfer gear can reduce weight and make the drive train cost-effective.

[0029] One embodiment of the drive train provides a first freewheel mechanism. The freewheel mechanism can be configured, for example, as a pawl-type freewheel mechanism or a roller-type freewheel mechanism. In the blocked state of the freewheel mechanism, two elements connected to the freewheel mechanism can be connected to each other in a rotationally fixed manner via the freewheel mechanism. However, in the released state, the two elements connected to the freewheel mechanism can be decoupled from each other. The freewheel mechanism can, for example, autonomously switch between the blocked state and the released state depending on the relative rotational direction of the two elements of the freewheel mechanism. In the released state, no significant torque or speed transmission occurs between the elements connected via the freewheel mechanism. In the blocked state, torque and speed transmission can occur between the elements connected via the freewheel mechanism. Because the two elements initially rotate relative to each other in a first relative rotational direction, the freewheel mechanism can connect the two elements in a rotationally fixed manner, thereby achieving the blocked state. Once the blocked state is achieved, the two elements cannot rotate relative to each other in the first relative rotational direction. Conversely, in a second, opposite relative rotational direction, the two elements can be decoupled from each other via the freewheel mechanism. Thus, the freewheel mechanism can transition from the blocked state to the released state.

[0030] The crankshaft can be mechanically operatively connected to the driven shaft via the first freewheel mechanism. This allows the crankshaft to be decoupled from the driven shaft. This prevents the crankshaft from being driven due to the inertia of the individual motors when the rider suddenly stops pedaling. This makes the drive train particularly comfortable to use. Decoupling via the first freewheel can be particularly useful due to the high inertia of the first motor and any additional motors (such as the second motor) in the drive train, and the potentially high rotational speeds caused by the transmission.

[0031] In one embodiment of the drive train, it is provided that the crankshaft can be connected to the third planetary carrier in a rotationally fixed manner by means of a first freewheel mechanism. Therefore, only the crankshaft can be directly disconnected. Thus, for example, the inertia of the first motor and, if present, the optional second motor can be disconnected from the crankshaft. In this structural form, the third ring gear can be permanently connected to the driven shaft in a rotationally fixed manner, while the first planetary carrier can be permanently connected to the third sun gear in a rotationally fixed manner. In this structural form, the integration of the freewheel mechanism is particularly easy. In addition, the drive train can therefore be particularly short axially. In addition, in the disconnected state, the differential speed on the first freewheel mechanism can be particularly low. Alternatively, instead of the first freewheel mechanism, a permanent rotationally fixed connection between the third planetary carrier and the crankshaft can also be provided.

[0032] In one embodiment of the drive train, the third ring gear can be connected to the driven shaft in a rotationally fixed manner via a first freewheel mechanism. This allows the driven shaft to be decoupled from the rest of the drive train. In this configuration, 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 mechanism, a permanent rotationally fixed connection between the third ring gear and the driven shaft can also be provided.

[0033] In one embodiment of the drive train, it is provided that the first planet carrier can be connected to the third sun gear in a rotationally fixed manner by means of a first freewheel mechanism. Thus, by interrupting the torque transmission on the third planetary gear set, the torque transmission from the crankshaft to the driven shaft can also be interrupted. In this structural form, the first freewheel mechanism can, for example, transmit particularly low torques in the blocked state. As a result, the first freewheel mechanism can be particularly small and light. In this structural form, the crankshaft can be permanently connected to the third planet carrier in a rotationally fixed manner, while the third ring gear can be permanently connected to the driven shaft in a rotationally fixed manner. Alternatively, instead of the first freewheel mechanism, the first planet carrier can be permanently connected to the third sun gear in a rotationally fixed manner.

[0034] In one embodiment of the drive train, it is provided that the drive train has a second freewheel mechanism. The second freewheel mechanism can be designed to prevent the first motor shaft from rotating in one direction of rotation. For example, the second freewheel mechanism can only release the motor shaft from rotating in a direction that is used to reduce the speed ratio of the transmission. As a result, high loads can be reliably supported, for example when the full weight of the rider acts on the pedals. For example, starting torques from the rider that cannot be supported by the first motor can also be supported. In addition, the bicycle can be started smoothly even if the energy supply of the first motor fails. If the second freewheel mechanism is not provided, a relatively high speed ratio can be provided for a particularly easy start.

[0035] In one embodiment of the drive train, it is provided that the first motor shaft can be fixed, for example, on a stationary component, by means of the second freewheel mechanism.Thus, the torque acting on the second freewheel mechanism is particularly small, since the pedaling force has already been transmitted and shifted via the transmission.

[0036] In one embodiment of the drive train, the rotating elements of the first planetary gear set can be immobilized by means of a second freewheel mechanism. For example, the first planet carrier can be immobilized by means of the second freewheel mechanism. Alternatively, for example, the first ring gear can be immobilized by means of the second freewheel mechanism. In these configurations, for example, the second planet carrier is immobilized. This facilitates integration of the second freewheel mechanism.

[0037] A second aspect relates to a bicycle. The bicycle can be configured, for example, as an electric power-assisted bicycle. The bicycle can include a drive train according to the first aspect. Therefore, the corresponding features and advantages of the first aspect represent the features and advantages of the second aspect, and vice versa. The bicycle can include a bicycle frame and at least one running wheel. The driven shaft of the drive train can be operatively connected to the at least one running wheel of the bicycle, for example, via a chain or belt. Therefore, the running wheel can be a driven running wheel. The running wheel can, for example, include a rim and a tire. The running wheel can also include a hub. The hub can have an additional freewheel mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A first embodiment of a drive train for a bicycle is schematically shown;

[0039] Figure 2 A second embodiment of a drive train is schematically shown;

[0040] Figure 3 A third embodiment of a drive train is schematically shown;

[0041] Figure 4 A fourth embodiment of a drive train is schematically shown;

[0042] Figure 5 A fifth embodiment of a drive train is schematically shown;

[0043] Figure 6 A sixth embodiment of a drive train is schematically shown;

[0044] Figure 7 A seventh embodiment of a drive train is schematically shown;

[0045] Figure 8 An eighth embodiment of a drive train is schematically shown;

[0046] Figure 9 A ninth embodiment of a drive train is schematically shown;

[0047] Figure 10 A tenth embodiment of a drive train is schematically shown;

[0048] Figure 11 An eleventh embodiment of a drive train is schematically shown. DETAILED DESCRIPTION

[0049] Figure 1A first embodiment of a drive train for a bicycle is schematically shown. The drive train includes a crankshaft 10, a driven shaft 12, a transmission 14, and a first electric machine EM1 with a first motor shaft W1. The drive train is configured for continuously variable transmission between the crankshaft 10 and the driven shaft 12. The crankshaft 10 defines an axial direction and extends through the transmission 14 as a central axis. The first motor shaft W1 is arranged coaxially with the crankshaft 10.

[0050] The transmission 14 includes a first planetary gear set 20 having a first sun gear 22, a first planet carrier 24, and a first ring gear 26. A set of first planetary gears 28 is rotatably supported on the first planet carrier 24 and meshes with the first sun gear 22 and the first ring gear 26, respectively. The transmission 14 includes a second planetary gear set 30 having a second sun gear 32, a second planet carrier 34, and a second ring gear 36. A set of second planetary gears 38 is rotatably supported on the second planet carrier 34 and meshes with the second sun gear 32 and the second ring gear 36, respectively. The transmission 14 includes a third planetary gear set 40 having 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 supported on the third planet carrier 44 and meshes with the third sun gear 42 and the third ring gear 46, respectively. The first electric machine EM1 can be used to continuously vary the speed ratio from the crankshaft 10 via the third planetary gear set 40 to the output shaft 12 .

[0051] The second planetary gear set 30 is nested radially outside the first planetary gear set 20. The effective diameters of all rotating elements of the second planetary gear set 30 are larger than the effective diameters of all rotating elements of the first planetary gear set 20. Depending on the design, the effective diameters of the planetary gears 38 of the second planetary gear set 30 may be smaller, equal to, or larger than the respective effective diameters of the planetary gears 28 of the first planetary gear set 20. Furthermore, the second planetary gear set 30 is at least partially arranged axially in the same region as the first planetary gear set 20. This results in a particularly short axial drive train. The third planetary gear set 40 is arranged axially adjacent to the first and second planetary gear sets 20, 30. In the example shown, the third planetary gear set 40 extends radially overlapping the second and first planetary gear sets 30, 20. The three planetary gear sets 20, 30, and 40 are arranged coaxially with the crankshaft 10.

[0052] 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 can be connected to the third sun gear 42 in a rotationally fixed manner. 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 from a common component, which in the example shown is a one-piece element having internal and external toothing. The third planet carrier 44 can be connected to the crankshaft 10 in a rotationally fixed manner. The third ring gear 46 can be connected to the output shaft 12 in a rotationally fixed manner.

[0053] The crankshaft 10 can be mechanically operatively connected to the output shaft 12 via an optional first freewheel F1. In a first embodiment, the third planet carrier 44 can be connected to the crankshaft 10 in a rotationally fixed manner via the first freewheel F1. In the first embodiment, the first planet carrier 24 and the third sun gear 42 are permanently connected to each other in a rotationally fixed manner. In the first embodiment, the third ring gear 46 is permanently connected to the output shaft 12 in a rotationally fixed manner. The second planet carrier 34 is permanently connected to a stationary component 50 in the form of a housing and is therefore fixed. The connection between the stationary component 50 and the second planet carrier 34 is arranged axially on the motor side relative to the first and second planetary gear sets 20, 30. The connection between the first planet carrier 24 and the second ring gear 36 is arranged axially on the output side relative to the first and second planetary gear sets 20, 30.

[0054] Figure 2 A second embodiment of a drive train is shown which is constructed similarly to the first embodiment. Only the differences from the first embodiment are discussed below.

[0055] In the second embodiment, second planet carrier 34 is permanently connected to third ring gear 46 in a rotationally fixed manner, rather than being fixed. Accordingly, the connection between first planet carrier 24 and second ring gear 36 is now arranged axially on the motor side relative to first planetary gear set 20 and second planetary gear set 30. This design of transmission 14 and the above-described connection can also be provided in other embodiments that are similar in design to the first embodiment in terms of these components and connections.

[0056] Figure 3 A third embodiment of a drive train is shown, which additionally 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, but is otherwise constructed 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.

[0057] For this connection, the connecting gear 60 includes 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 transfer gear 62. A set of fourth planetary gears 78 are rotatably mounted on the fourth planet carrier 74 and mesh with the fourth sun gear 72 and the fourth ring gear 76, respectively. The fourth sun gear 72 is permanently rotationally fixedly connected to the second motor shaft W2 and thus forms the input shaft of the connecting gear 60. The fourth ring gear 76 is permanently rotationally fixedly connected to the stationary component 50 and is therefore fixed. The transfer gear 62 includes three spur gears 64, 66, and 68, each meshing in pairs. The spur gear 64, located on the motor side in the torque flow, is permanently rotationally fixedly connected to the fourth planet carrier 74. The spur gear 68, located on the output side in the torque flow, is permanently rotationally fixedly connected to the output shaft 12 or consists of the output shaft. The spur gear 68 on the output side thus forms the output shaft of the connecting gear 60 .

[0058] This results in a connection of the second electric machine EM2 on the output side of the torque flow, allowing it to directly drive the output shaft 12. The two motor shafts W1 and W2 are arranged with parallel axes and offset. The transfer mechanism 62 compensates for this offset. Alternatively or additionally, the transfer mechanism 62 provides a speed ratio between the fourth planetary carrier 74 and the output shaft 12, depending on the selected design and the effective diameter of the spur gear or pinion. The fourth planetary gear set 70 provides a compact high-speed ratio for the second electric machine EM2.

[0059] Figure 4 A fourth embodiment of a drive train is shown which is similar in construction to the third embodiment. Only the differences from the third embodiment are discussed below.

[0060] In the fourth embodiment, the second electric machine EM2 is connected to the remaining drivetrain in a different manner. The output shaft of the connecting gear 60 (which is again formed by the spur gear 68 closest to the output side of the transfer gear 62) can be connected in a rotationally fixed manner to the third planetary carrier 44 or is formed by the third planetary carrier 44. In the fourth embodiment, the output shaft is permanently connected in a rotationally fixed manner to the third planetary carrier 44 in the example shown. Thus, the second electric machine EM2 is connected to the transmission 14 on the drive side. This allows the driving force provided by the second electric machine EM2 to be transmitted to the output shaft 12 at a continuously adjustable speed ratio by the first electric machine EM1. In the fourth embodiment, the transfer gear 62 is arranged axially on the motor side relative to the third planetary gear set 40, rather than in the same axial region or on the output side as in the third embodiment.

[0061] Figure 5A fifth embodiment of a drive train is shown which is similar in construction to the third embodiment. Only the differences from the third embodiment are discussed below.

[0062] In the fifth embodiment, in contrast to the first and third embodiments, the second planetary carrier 34 is connected axially to the stationary component 50 on the output side, and therefore between the first planetary gear set 20 or the second planetary gear set 30 and the third planetary gear set 40. The connection between the second ring gear 36 and the first planetary carrier 24 is arranged axially on the motor side and between the first electric machine EM1 and the first planetary gear set 20 or the second planetary gear set 30.

[0063] Figure 6 A sixth embodiment of a drive train is shown which is similar in construction to the third embodiment. Only the differences from the third embodiment are discussed below.

[0064] In the sixth embodiment, the first freewheel mechanism F1 is arranged differently. The first planet carrier 24 can be connected to the third sun gear 42 in a rotationally fixed manner via the first freewheel mechanism F1. Consequently, there is no permanent rotationally fixed connection between the first planet carrier 24 and the third sun gear 42. However, the crankshaft 10 and the third planet carrier 44 are now permanently rotationally fixedly connected to one another. Furthermore, compared to the third embodiment, the third planetary gear set 40 is now positioned axially further toward the driven side relative to the transfer mechanism 62.

[0065] Figure 7 A seventh embodiment of a drive train is shown which is similar in construction to the third embodiment. Only the differences from the third embodiment are discussed below.

[0066] In the seventh embodiment, the first freewheel mechanism F1 is arranged differently from the third and sixth embodiments. The third ring gear 46 can be connected to the driven shaft 12 in a rotationally fixed manner via the first freewheel mechanism F1. Therefore, no permanent rotationally fixed connection is provided between the third ring gear 46 and the driven shaft 12. However, the crankshaft 10 and the third planetary carrier 44 are now permanently rotationally fixedly connected to each other. Compared to the sixth embodiment, the first planetary carrier 24 and the third sun gear 42 are also now permanently rotationally fixedly connected to each other. Furthermore, compared to the third embodiment, the third planetary gear set 40 is now positioned axially closer to the motor than the transfer mechanism 62. Therefore, the first freewheel mechanism F1 is arranged axially between the third planetary gear set 40 and the transfer mechanism 62.

[0067] Figure 8 An eighth embodiment of a drive train is shown, which is similar in design to the third embodiment. Only the differences from the third embodiment are discussed below.

[0068] In the eighth embodiment, the transmission gear 62 of the connecting gear 60 is designed differently. Instead of three spur gear stages, a chain gear 80 is now provided. A first pinion 82 of the chain gear 80 is arranged on the motor side in the torque flow and is permanently connected to the fourth planet carrier 74 in a rotationally fixed manner. A second pinion 84 of the chain gear 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 to the output shaft 12 in a rotationally fixed manner or is formed by the output shaft.

[0069] Figure 9 A ninth embodiment of a drive train is shown, which additionally features a second freewheel mechanism F2 and is otherwise identical to the third embodiment. The second freewheel mechanism F2 is configured to prevent the first motor shaft W1 from rotating in one direction of rotation. However, in the opposite direction of rotation, the first motor shaft W1 is released and can rotate.

[0070] In the ninth embodiment, the first motor shaft W1 can be immobilized by means of a second freewheel F2. To this end, in the blocked 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 the first motor shaft W1 can be rotated by the first electric machine EM1 only in one direction of rotation, which increases the speed ratio of the third planetary gear set 40 from the third planet carrier 44 to the third ring gear 46.

[0071] Figure 10 A tenth embodiment of a drive train is shown, and Figure 11 The eleventh embodiment of the drive train is shown. In both embodiments, the rotating elements of the first planetary gear set 20 can be immobilized by means of the second freewheel F2, thereby preventing the first motor shaft W1 from rotating in one direction, as in the ninth embodiment. In the tenth embodiment, the first planet carrier 24 can be connected to the stationary component 50 in a rotationally fixed manner by means of the second freewheel element F2, thereby immobilizing it. In the eleventh embodiment, for this purpose, the first ring gear 26 can be connected to the stationary component 50 in a rotationally fixed manner by means of the second freewheel element F2, thereby immobilizing it. Otherwise, the tenth and eleventh embodiments are constructed identically to the ninth embodiment.

[0072] Reference Signs List

[0073] 10 crankshaft

[0074] 12 driven shaft

[0075] 14 Transmission

[0076] 20, 30, 40, 70 planetary gear sets

[0077] 22, 32, 42, 72 sun gears

[0078] 24, 34, 44, 74 planetary carriers

[0079] 26, 36, 46, 76 ring gears

[0080] 28, 38, 48, 78 planetary gears

[0081] 50 Stationary components

[0082] 60 Connecting the transmission

[0083] 62 Transmission gear

[0084] 64, 66, 68 cylindrical gears

[0085] 80 chain drive mechanism

[0086] 82, 84 pinion

[0087] EM1;EM2 motors

[0088] W1, W2 motor shaft

[0089] F1; F2 freewheel mechanism

Claims

1. A drive train for a bicycle, comprising 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 configured for continuously variable transmission between the crankshaft (10) and the driven shaft (12), wherein the transmission (14) comprises a first planetary gear set (20) having a first sun gear (22), a first planetary carrier (24) and a first ring gear (26), a second planetary gear set (30) having a second sun gear (32), a second planetary carrier (34) and a second ring gear (36), and a third planetary gear set (40) having a third sun gear (42), a third planetary carrier (44) and a third ring gear (46), wherein the first motor shaft (W1) and the first sun gear (22) are permanently anti-rotatable relative to each other. connection, wherein the first planetary carrier (24) is permanently connected to the second ring gear (36) in a rotationally fixed manner, wherein the first planetary carrier (24) can be connected to the third sun gear (42) in a rotationally fixed manner, wherein the first ring gear (26) is permanently connected to the second sun gear (32) in a rotationally fixed manner, wherein the third planetary carrier (44) can be connected to the crankshaft (10) in a rotationally fixed manner, wherein the third ring gear (46) can be connected to the driven shaft (12) in a rotationally fixed manner, wherein the second planetary gear set (30) is nested in the first planetary gear set (20) from the radial outside.

2. The drive system 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. The drive system according to claim 1 or 2, characterized in that: The second planet carrier (34) is stationary.

4. The drive system 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 any 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 transmission (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 wherein the output shaft can be mechanically connected to the driven shaft (12).

6. The drive system according to claim 5, characterized in that: The output shaft can be connected to the output shaft (12) in a rotationally fixed manner.

7. The drive system according to claim 5, characterized in that: The output shaft can be connected to the third planet carrier (44) in a rotationally fixed manner.

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

9. Drive train according to any one of the preceding claims, characterized in that The drive train has a first freewheel (F1), wherein the crankshaft (10) can be mechanically operatively connected to the output shaft (12) by means of the first freewheel (F1).

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

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

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

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

14. The drive system according to claim 13, characterized in that: The first motor shaft (W1) can be immobilized by means of the second freewheel mechanism (F2).

15. The drive system according to claim 13, characterized in that: The rotating element of the first planetary gear set (20) can be fixed by means of the second free wheel mechanism (F2).

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