CN117460665A - Electric middle-set driving unit - Google Patents

Abstract

A vehicle can include a pedal assembly, a motor assembly, and a drive unit that can be used to allow selective use of one or both of the pedal assembly and the motor assembly to transmit power to driven wheels of the vehicle. The drive unit can include a gearbox that can house components that form at least a portion of a first power path between the pedal assembly and the driven wheel and a second power path between the motor assembly and the driven wheel. The first power path and the second power path may converge at a component within the gearbox. A one-way bearing located at a point in the first and second power paths prior to convergence of the power paths can inhibit or prevent the pedal assembly from being affected by operation of the motor assembly and can inhibit or prevent the motor assembly from being affected by operation of the pedal assembly.

Description

Electric middle-set driving unit

Incorporated by reference to any priority application

Any and all applications for which foreign or domestic priority claims are identified in the application data sheet filed with the present application are incorporated herein by reference in accordance with 37cfr 1.57.

The present application claims priority from U.S. provisional patent application No. 63/260,729 filed 8/30 of 2021 and U.S. provisional patent application No. 63/190,403 filed 5/19 of 2021, each of which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates generally to wheeled vehicles, such as bicycles and tricycles that include a pedal assembly and a motor assembly.

Background

The wheeled vehicle may be driven by a pedal assembly that rotates a sprocket axially offset from the driven wheels of the vehicle. The chain may be used to transfer power from the sprocket to the driven wheels of the vehicle. Such vehicles may alternatively be driven by an electric motor configured to transmit power to driven wheels of the vehicle. When the motor is also used to drive the sprocket, operation of the motor can affect operation of the pedal assembly, thereby driving the pedal assembly to move in an undesirable manner. The presence of the motor also introduces frictional losses in the operation of the pedal assembly.

Disclosure of Invention

In a first broad aspect, there is provided a gearbox suitable for use in a mid-drive electric bicycle having pedals and driven wheels, the gearbox comprising: a motor; a plurality of gears; a first one-way bearing; a second one-way bearing; the first one-way bearing is configured such that power from the motor can be transmitted to the driven wheel; the second one-way bearing is configured such that power from the foot pedal may be transferred to the driven wheel; and the gearbox is configured such that a user can drive the electric bicycle by: only through the foot pedal, only through the motor, and simultaneously through the foot pedal and the motor.

The gearbox may include a sprocket configured to receive power from the motor and the foot pedals and transmit the power to the drive wheels via a chain. The gearbox may further comprise a bottom bracket shaft rotatably coupled to the foot pedal, wherein the sprocket is rotatably coupled to an output gear supported on the bottom bracket shaft. The output gear may be conditionally rotationally coupled to the bottom bracket shaft by the second one-way bearing. The output gear may be supported on the bottom bracket axle by a swivel bearing that allows the output gear to rotate independently of the bottom bracket axle when not powered by the foot pedals.

The plurality of gears may include an intermediate step gear set that forms part of a motor power path from the motor to the sprocket. The intermediate step gear set may include an upper step gear set conditionally rotationally coupled to a lower step gear set by the first one-way bearing. The gearbox may form part of a mid-drive unit axially offset from the axis of rotation of the driven wheel.

In another broad aspect, there is provided a bicycle comprising: a frame; a driven wheel supported by the frame; a pedal assembly; a motor; and a gearbox supported by the frame, the gearbox comprising: a first one-way bearing forming part of a motor power path between the motor and an output gear operatively coupled to the driven wheel to transmit power thereto; and a second one-way bearing forming part of a pedal power path between the pedal assembly and the output gear.

The pedal assembly may include: a bottom bracket axle extending through at least a portion of the gearbox; and first and second pedal cranks rotatably coupled to the bottom bracket shaft at respective ends thereof. The output gear may be supported on the bottom bracket axle by the second one-way bearing.

The output gear may be supported on the bottom bracket axle by a swivel bearing, and the gearbox further comprises a pedal output gear supported on the bottom bracket axle by the second one-way bearing. The first one-way bearing may support a motor drive gear on an intermediate shaft axially offset from the bottom bracket shaft, the motor drive gear being operatively connected to the motor. The intermediate shaft may be rotatably coupled to a first offset gear engaged with the pedal output gear and a second offset gear engaged with the output gear. The motor drive gear may be operatively connected to the motor through an intermediate step gear set supported by a step gear shaft.

In another embodiment, a gearbox configured to be secured to a bicycle frame is provided, the gearbox comprising: a sprocket configured to engage with a chain of the bicycle to transmit power to a drive wheel of the bicycle via the chain; a bottom bracket axle configured to receive power from a pedal assembly of the bicycle; a step gear configured to receive power from the motor; a first one-way bearing forming at least a portion of a pedal power path between the bottom bracket shaft and an output gear operatively coupled to the sprocket; and a second one-way bearing forming at least a portion of a motor power path between the step gear and the output gear operably coupled to the sprocket.

The output gear may be supported on the bottom bracket axle by the first one-way bearing. The first one-way bearing and the output gear may be supported on the bottom bracket shaft at different locations along the bottom bracket shaft. The step gear may be supported on a step gear shaft by the second one-way bearing. The gearbox may further comprise the motor positioned at least partially within a housing of the gearbox.

Drawings

The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings. In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, like numerals typically identify like components unless context dictates otherwise.

Fig. 1A shows a perspective view of an embodiment of a vehicle including a pedal assembly and a center drive unit including an electric motor configured to power the vehicle. Fig. 1B is a right side view of the vehicle of fig. 1A. Fig. 1C is a left side view of the vehicle of fig. 1A. Fig. 1D is a top view of the vehicle of fig. 1A.

Fig. 2A shows a perspective view of the transmission of the vehicle of fig. 1A shown independent of the vehicle. Fig. 2B shows a right side view of the gearbox of fig. 2A. Fig. 2C shows a left side view of the gearbox of fig. 2A.

FIG. 3A shows a perspective view of certain components of the transmission of FIG. 2A with the housing and certain additional components removed. FIG. 3B shows an exploded assembly view of the transmission components of FIG. 3A.

Fig. 4A shows a cross-sectional view of the components of fig. 3A, wherein the components are moved relative to one another such that the axes of each rotational axis are coplanar with one another. Fig. 4B shows a perspective view of the components of fig. 3A arranged as shown in fig. 4A.

FIG. 5 shows a cross-sectional view of components of an alternative embodiment of a gearbox without a planetary gear set connected to the motor, the components being arranged in the same position as in FIG. 4A.

FIG. 6A is a schematic illustration of components of the transmission of FIG. 2A. FIG. 6B is a schematic diagram of FIG. 6A, wherein a power path for power provided via the pedal assembly is shown. Fig. 6C is a schematic diagram of fig. 6A, wherein a power path for power provided via the motor assembly is shown. FIG. 6D is a schematic diagram of FIG. 6A, showing a combined power path for power supplied simultaneously via the pedal assembly and the motor assembly.

Fig. 7A to 7C are perspective views showing the transmission of fig. 2A mounted to the vehicle of fig. 1A.

FIG. 8 is a schematic view of certain components of an alternative embodiment of the transmission in which the power paths from the pedal assembly and motor assembly converge at a component offset from the bottom bracket axle.

Fig. 9A shows a perspective view of another embodiment of a vehicle including a pedal assembly and an alternative embodiment of a center drive unit including a motor configured to power the vehicle. Fig. 9B is a right side view of the vehicle of fig. 9A. Fig. 9C is a left side view of the vehicle of fig. 9A. Fig. 9D is a top view of the vehicle of fig. 9A.

Fig. 10A shows a perspective view of the transmission of the vehicle of fig. 9A shown independent of the vehicle. Fig. 10B shows a right side view of the transmission of fig. 10A. Fig. 10C shows a left side view of the transmission of fig. 10A.

FIG. 11A shows a perspective view of certain components of the transmission of FIG. 10A with the housing and certain additional components removed. FIG. 11B shows an exploded assembly view of the transmission components of FIG. 11A.

Fig. 12A shows a perspective view of the components of fig. 10A, wherein the components are moved relative to one another such that the axes of each rotational axis are substantially coplanar with one another. Fig. 12B shows a side view of the components of fig. 11A arranged as shown in fig. 12A. Fig. 12C shows a partial cross-sectional view of certain components of fig. 11A arranged as shown in fig. 12A.

FIG. 13A is a schematic illustration of components of the transmission of FIG. 10A. Fig. 13B is a schematic view of fig. 13A, wherein a power path for power provided via the pedal assembly is shown. Fig. 13C is a schematic diagram of fig. 13A, wherein a power path for power provided via the motor assembly is shown. Fig. 13D is a schematic diagram of fig. 13A, showing a combined power path for power supplied simultaneously via the pedal assembly and the motor assembly.

Fig. 14A and 14B are perspective views showing the transmission of fig. 10A mounted to the vehicle of fig. 9A.

Detailed Description

The disclosed technology relates to an electric drive unit that can be used with a vehicle such as an electric bicycle. At least some components of the electric drive unit may be positioned in a middle portion of the vehicle, such as between the front and rear wheels of the vehicle. In some embodiments, the components located in the middle portion of the vehicle may include a center drive motor that may be used with an electric bicycle (also referred to as a center drive electric bicycle). Such electric mid-drive units may be configured for use on a variety of bicycles, including bicycles, tricycles, and other pedal vehicles. Some embodiments of the central drive unit and its components are disclosed in the accompanying drawings, which form a part of the present invention. In some embodiments, the central drive unit may include a small motor, a reduction gear, and at least two one-way bearings.

SUMMARY

In some embodiments, a vehicle, such as a mid-drive electric bicycle, may include a gearbox. The gearbox may include an electric motor and one or more gears. The motor may be powered by a battery, which may be placed in or near the gearbox, or elsewhere on the bicycle. The gearbox may be configured to mate with a portion of a bicycle, such as a bottom bracket shell of a bicycle. The bottom bracket shell may be a tubular member that may extend substantially horizontal to the ground when the bicycle is operated, and/or the bottom bracket shell may be a bracket through which the manual pedal mechanism is typically mounted to the bicycle, as discussed in more detail herein.

The gearbox may include an electric motor, a plurality of gears, a first one-way bearing, and a second one-way bearing. The first one-way bearing may be configured to form or connect a portion of a first power path to enable power from the motor to be transferred to the driven wheel of the bicycle and/or to isolate or disconnect the motor from a second power path that enables power to be transferred from the foot pedal of the pedal assembly of the bicycle to the driven wheel of the bicycle. The second one-way bearing may be configured to form or connect a portion of a second power path that enables power from the pedal assembly to be transferred to the driven wheel and/or isolates or disconnects the pedal assembly from the first power path. The gearbox may be configured to enable a user to drive the bicycle (e.g., apply power to the driven wheels) with both the pedal assembly and the motor.

In some implementations, due to the one-way bearings positioned along each power path, a user may hold the pedal in a stationary position or rotate the pedal rearward while the motor provides power to the driven wheel. Similarly, in various embodiments, user pedaling does not cause actuation of the motor and/or the motor does not provide resistance against pedaling. In some embodiments, the size of the motor may be small enough to avoid interfering with the ability of the user to pedal the bicycle.

FIGS. 1A through 7C

Fig. 1A shows a perspective view of an embodiment of a vehicle including a pedal assembly and a center drive unit including an electric motor configured to power the vehicle. Fig. 1B is a right side view of the vehicle of fig. 1A. Fig. 1C is a left side view of the vehicle of fig. 1A. Fig. 1D is a top view of the vehicle of fig. 1A.

In the illustrated embodiment, the vehicle 10 includes a bicycle that includes a front wheel 20, a rear wheel 30, and a frame 40. The frame 400 may include, among other components, a down tube 42 and a seat tube 44. The gearbox 100 may be located in the region where the down tube 42 or axial projection thereof intersects the seat tube 44 or axial projection thereof. The bottom bracket axis, not visible in fig. 1A, may be located at the intersection of the down tube 42 and the seat tube 44. The bottom bracket axle 130 extends through the bottom bracket and is connected at each end to a pedal crank 134 that supports the pedal 50 at its outer end. The gearbox 100 may include a sprocket 144 connected to the sprocket teeth or rear shift disk of the rear wheel 30 via a chain 60, allowing the rear wheel 30 to be driven by power transmitted via the chain. The rear wheel 30 in this arrangement may also be referred to herein as a driven wheel. In some variations, the front wheel 20 is a driven wheel.

As described in greater detail herein, a motor assembly and pedal assembly (such as crank 134 and pedal 50) within a gearbox (such as gearbox 100) may be used to transfer power to driven wheels of a vehicle, such as rear wheels 30 of vehicle 10. Power may be transferred along at least partially independent power paths through the transmission 100, where the power paths may converge into a common output segment at a component within the transmission 100. Above this common output section, the individual portions of the power paths may be isolated from each other by respective unidirectional bearings positioned along each power path.

Fig. 2A shows a perspective view of the transmission of the vehicle of fig. 1A shown independent of the vehicle. Fig. 2B shows a right side view of the gearbox of fig. 2A. Fig. 2C shows a left side view of the gearbox of fig. 2A. The gearbox 100 may include a housing 110 that encloses a plurality of components arranged along a plurality of rotational axes. The housing 110 may be plastic and/or metal, such as die cast metal, and may be sized to be inserted or otherwise extended into the space between the components of the vehicle frame.

As discussed in more detail elsewhere herein, the housing 110 may be fixed relative to the frame of the vehicle. For example, in some embodiments, the transmission 100 is assembled to the vehicle frame via a crankshaft. In some embodiments, the transmission 100 may be assembled in different ways. For example, the gearbox 100 may be attached to a bracket and/or frame of the vehicle, such as with screws or other fasteners. The gearbox 100 may be welded or bolted to the vehicle frame or intermediate component, or may be constructed as an integral part of the vehicle, or connected to the vehicle frame in any suitable manner.

FIG. 3A shows a perspective view of certain components of the transmission of FIG. 2A with the housing and certain additional components removed. FIG. 3B shows an exploded assembly view of the transmission components of FIG. 3A. Fig. 4A shows a cross-sectional view of the components of fig. 3A, wherein the components are moved relative to one another such that the axes of each rotational axis are coplanar with one another. Fig. 4B shows a perspective view of the components of fig. 3A arranged as shown in fig. 4A. FIG. 6A is a schematic illustration of components of the transmission of FIG. 2A.

For example, as can be seen in fig. 4A, the gearbox 100 includes a bottom bracket axle 130 configured to rotate about a first axis of rotation 138. The bottom bracket axle 130 may be operably connected to the crank 134 of the pedal assembly at each end, allowing the crank 134 of the pedal assembly to rotate in a first direction to drive the coupled bottom bracket axle 130 to rotate about the first axis of rotation 138.

A first one-way bearing 140 (also referred to herein as a pedal one-way bearing 140) is coaxial with both the bottom bracket shaft 130 and the output gear 142. A sprocket 144, which may be integrally formed with the output gear 142 or rotatably fixed relative to the output gear 142, is also coaxial with the pedal one-way bearing 140. The bottom bracket axle 130 extends through or is otherwise secured to the inner race of the pedal one-way bearing 140 such that rotation of the main axle about the first rotational axis 138 causes the inner race of the pedal one-way bearing to rotate about the first rotational axis 138.

The pedal one-way bearing 140 is configured to transfer torque between the bottom bracket shaft 130 and the output gear 142 when the crank 134 of the pedal assembly is driven in a first direction. Driving the inner race of the pedal one-way bearing 140 in a first direction locks the inner race of the pedal one-way bearing 140 relative to its outer race, allowing torque to be transferred therebetween.

The first direction may be a forward direction in which the crank 134 moves such that the crank 134 moves about a circular path that includes the crank 134 moving from an upward vertical direction to a forward direction in the direction of travel of the vehicle or toward the front wheels of the vehicle. Torque transfer from pedal one-way bearing 140 moves output gear 142 and rotatably coupled sprocket 144 in a first direction. Rotation of the sprocket 144 may drive the chain to rotate about the sprocket 144, which in turn drives gears on the drive wheels to drive the vehicle. This power path is shown in fig. 6B as power path 190A.

However, when the output gear 142 is driven in the first direction via other means, movement of the outer race of the pedal one-way bearing 140 coupled to the output gear 142 does not cause torque to the inner race of the pedal one-way bearing 140 without applying torque to the bottom bracket shaft 130 via the crank 134. Driving the output gear 142 in the first direction will allow the outer race of the pedal one-way bearing 140 to slide relative to its inner race and will not transfer torque to the bottom bracket axle 130 through the pedal one-way bearing 140. The pedal one-way bearing provides a conditional rotational coupling between the bottom bracket shaft 130 and the output gear 142 because relative movement between the inner and outer races of the pedal one-way bearing 140 in one direction causes the pedal one-way bearing 140 to lock and provide a rotational coupling. Relative movement in the other direction allows the pedal one-way bearing 140 to slide, thereby not providing a rotational coupling.

Any suitable one-way bearing may be used, including a sprag bearing, or a bearing with an intermediate ball bearing or other bearing member, such as a needle bearing biased into an asymmetric retention space.

The gearbox 100 may include a motor assembly 150 that may provide power to the vehicle that is used in lieu of or in addition to pedal power applied via the crank 134. The motor assembly 150 may include a motor 152 and an output rotating member 156. Depending on the speed of the motor 152, the motor assembly 150 may also include a speed reducing component, such as a planetary gear system 154. The planetary gear system 154 may include a sun gear that may be directly driven by the motor and a plurality of planet gears that are in turn driven by the sun gear. The output rotating element 156 may be coupled to a plurality of planetary gears in turn such that the output rotating element 156 may be driven at a slower angular velocity than the sun gear and the motor 152, and the torque output of the overall motor assembly 150 may be increased relative to the torque output of the motor 152 without the need to reduce the planetary gear system 154. In some variations, the speed reducing component includes a gear train (e.g., a plurality of spur gears), a belt drive, a chain drive, and the like.

The motor 152 and the output rotary member 156 are coaxial with each other and rotatable about a second axis of rotation 158. In the illustrated embodiment, the output rotary member 156 includes an output gear 156, allowing the motor assembly to drive rotation of the axially offset member. However, in other embodiments, the output rotary element 156 may be a shaft that is coupleable to, for example, another axially aligned element.

In the illustrated embodiment, the planetary gear system 154 is depicted as a discrete element attached to the motor 152, although in other embodiments, the planetary gear system or other speed reducing components may be integrated into the housing of the motor 152 itself.

The motor assembly 150 is coupled to an intermediate step gear set 160 that includes a lower step gear 162 and an upper step gear 164. In some embodiments, the lower step gear 162 engages the motor output gear 156 of the motor assembly 100 and/or has an effective radius that is greater than the effective radius of the upper step gear 164. The lower step gear 162 is conditionally rotationally coupled to the upper step gear 164 via a second one-way bearing 170 (also referred to as a motor one-way bearing 170) and a step gear shaft 172 rotatably fixed to the upper step gear 164. The step gear shaft 172 is rotatably coupled to an inner race of the motor one-way bearing 170, and the upper step gear 164 is rotatably coupled to an outer race of the motor one-way bearing 170. Each of the lower step gear 162, the upper step gear 164, the motor one-way bearing 170, and the step gear shaft 172 may be coaxial with the third rotation axis 178 and configured to rotate about the third rotation axis 178.

When the motor assembly 150, and in particular the output gear 156, is driven in a first direction, the lower step gear 162 will be driven in a second direction opposite the first direction. In turn, the outer race of the motor one-way bearing 170 will be driven in the second direction. The motor one-way bearing 170 is oriented such that when the outer race is driven in the second direction, the motor one-way bearing locks and torque is transferred to the inner race of the motor one-way bearing 170 up to the step gear shaft 172 and the upper step gear 164. Thus, due to the orientation of the motor one-way bearing 170, driving the lower step gear 162 to rotate in the second direction causes each component of the intermediate step gear set 160 to be driven together as a single unit in the second direction. In turn, rotation of the upper step gear 164 in the second direction causes rotation of the output gear 142 and the rotatably coupled sprocket 144 in the first direction, and the chain in turn may drive the vehicle in the same forward direction as rotation of the pedal crank 134 in the first direction. This power path is shown in fig. 6C as power path 190B.

When the output gear 142 is driven in a first direction without the use of the motor assembly 150, such as by rotation of the pedal crank 134, the upper step gear 164 and step gear shaft 172 will be driven in a second direction. However, due to the orientation of the motor one-way bearing 170, rotation of the inner race of the motor one-way bearing 170 does not cause rotation of the outer race of the motor one-way bearing 170, and substantially no torque will be transferred from the step gear shaft 172 to the lower step gear 162.

When the motor assembly 150 is not being used to power the vehicle, the motor oneway bearing 170 isolates (e.g., disconnects) the motor assembly 150 from the pedal-driven operation of the vehicle. This inhibits or prevents, for example, the motor assembly 150 from adversely affecting the pedal-driven operation of the vehicle, as would occur due to frictional loading caused by rotation of the pedal crank 134 causing rotation of the rotor of the motor 152 relative to the stator of the motor 152.

In the illustrated embodiment, the motor one-way bearing 170 is located within the lower step gear 162, wherein an outer race of the motor one-way bearing 170 is coupled to the lower step gear 162. However, in other embodiments, the one-way bearing may be located elsewhere on the power path between the motor 152 and the output gear 142. For example, the upper step gear 164 may be connected to an outer race of the motor one-way bearing 170, while the lower step gear 162 is rotatably coupled to an inner race of the motor one-way bearing 170 via a step gear shaft 172. In other embodiments, such as those in which less gear reduction is provided between the motor 152 and the output gear 142, the race of the motor one-way bearing 170 may be directly connected to the output rotating element 156 of the motor assembly 150.

Similar to the isolation provided by the motor oneway bearing 170, the pedal oneway bearing 140 can isolate the pedal crank 134 from the motor drive operation of the vehicle. This enables the pedal supported by the pedal crank 134 to remain stationary during electric-only driving operation of the vehicle. This allows the rider to place his feet in a stable position during motor drive operation.

If both the motor assembly 150 and the pedal crank 134 are used to power the vehicle at the same time, the pedal one-way bearing 140 and the motor one-way bearing 170 may allow torque to be transferred from both the motor assembly 150 and the pedal crank 134 to the output gear 142 at the same time. This allows the vehicle to operate in a motor assist mode in which the rider can use the motor assembly 150 to provide supplemental power to the vehicle when stepping on the pedal.

The motor may be controlled in a number of ways. In some embodiments, the motor is controlled by a throttle (such as a thumb throttle) that is adjustable by a user. In some implementations, the motor provides drive assistance to the user. For example, the motor may provide power that supplements or augments the power provided by the user via the pedal. In some embodiments, the motor provides power when the user is not stepping on the pedal. In certain variations, the motor provides power when the user steps on the pedal. In certain implementations, the bicycle includes a sensor for controlling the motor, such as a torque sensor, a proximity sensor, or other sensor. For example, the motor may be actuated when a threshold torque level is detected and/or exceeded. This may enable automatic motion assistance of the motor and/or may allow a user to control operation of the motor through use of the pedal assembly, such as by applying an amount of torque greater than or equal to a threshold to the pedal assembly. In various embodiments, the bicycle may be powered by both the motor and the user via the pedal assembly.

Fig. 5 shows a cross-sectional view of an alternative gearbox 200. The gearbox 200 may have a motor assembly 250. In some embodiments, the motor assembly 250 includes a direct drive and/or does not include a planetary gear set. The gearbox 200 is shown with components arranged in the same relative positions as in fig. 4A. In such an embodiment, the motor 252 drives the output shaft 254 and the motor output gear 256 supported thereon at the same angular velocity as the motor 252. Such an arrangement may be suitable, for example, when motor 252 is configured to rotate at a lower speed than motor 152. For example, in some embodiments, the motor 252 may be configured to rotate at a speed of less than 4,000 rpm. In contrast, in some embodiments, the motor 152 used in conjunction with the planetary gear set 154 may be configured to rotate at speeds greater than 10,000 rpm. In some embodiments, the motor 152 may have an output angular speed of approximately 18,000rpm, but at each stage of the gearbox, different gear ratios may be utilized to accommodate a wide range of motor output speeds. For example, the range of suitable motor speeds for motors 152 and 252 may vary based on the gear reduction provided by intermediate step-gear sets 160 and 260 and any gear reduction that may be provided elsewhere in the drive trains of gearboxes 100 and 200.

Fig. 7A to 7C are perspective views showing the transmission of fig. 2A mounted to the vehicle of fig. 1A. As can be seen in fig. 7A, the outer housing 110 of the gearbox 100 may include a generally cylindrical engagement member 112 sized to fit into the radially inner wall of the bottom bracket shell 46. The engagement member 112 may include a plurality of radially extending ribs or fins 114 that may abut the inside of the bottom bracket shell to provide a friction fit therebetween. The leading edges of the fins 114 may be tapered to facilitate insertion into the bottom bracket shell 46.

As can be seen in fig. 7B, once the engagement member 112 is fully inserted into the bottom bracket shell 46, a portion of the bottom bracket axle 130 extends through the bottom bracket shell 46 and extends outwardly beyond the bottom bracket shell 46. The gearbox cover 118 may be inserted onto the exposed portion of the bottom bracket axle 130 and slid toward the bottom bracket shell 46 to abut and/or extend at least partially into the bottom bracket shell 46. In some embodiments, the gearbox cover 118 may be held in place at least in part via a friction fit with the bottom bracket shell 46. The gearbox cover 118 may include one or more swivel bearings configured to support the bottom bracket axle 130 at its free end and allow the bottom bracket axle 130 to rotate relative to the bottom bracket shell 46.

In fig. 7C, it can be seen that the gearbox cover 118 has been inserted into place, with the mounting of the gearbox 110 to the vehicle frame 40 completed. A pedal crank 134 (see fig. 1A) may be attached to each end of the bottom bracket shaft 130 and may cooperate with a friction fit between the components to hold the gearbox 100 in place on the vehicle frame.

Axial mounting of the gearbox 100 and/or the entire mid-drive unit may enable a quick and simple mounting process. However, a variety of alternative mounting procedures may be used in conjunction with various transmission and/or mid-drive unit designs. For example, in some embodiments, the gearbox may be mounted from the bottom of the vehicle, such as by moving vertically into corresponding mating brackets in the vehicle frame. In some embodiments, the gearbox may be mounted at least partially into a position where the foot pedal and/or crank mechanism is mounted to the bicycle. In some embodiments, the gearbox may be installed without modification to the bicycle frame. The installation of the gearbox and/or the mid-drive unit may facilitate the conversion and/or retrofitting of a non-powered bicycle to a powered bicycle.

In the transmission 100, the output gear 142 is rotatably coupled to the sprocket 144 and is configured to function as a torque combining member at which the two power paths converge, allowing the output gear 142 to receive torque from both the bottom bracket shaft 130 and the intermediate step gear set 160. However, in other embodiments, the output gear and sprocket may rotate independently of the bottom bracket, but supported by the bottom bracket, and the axially offset gear upstream of the power path may serve as the torque combining component.

FIG. 8

Fig. 8 schematically illustrates certain components of an alternative embodiment of the transmission, wherein the power paths from the pedal assembly and motor assembly converge at a component offset from the bottom bracket axle. Fig. 8 schematically illustrates an embodiment of a gearbox 300 comprising a torque combining gear axially offset from an output gear. The transmission 300 includes a bottom bracket shaft 330 rotatably coupled to a pedal crank 334. A pedal one-way bearing 340, which may be positioned concentrically within pedal output gear 336, provides a conditional rotational coupling between bottom bracket shaft 330 and pedal output gear 336. When the pedal crank 334 is driven in a first direction, such as by a user stepping on the vehicle, the pedal output gear 336 is driven in the first direction.

Rotation of the pedal output gear 336 in a first direction drives the first offset step gear 382 serving as a torque combining member to rotate about the offset shaft 386 in a second direction opposite the first direction. A second offset step gear 384 rotatably connected to the first offset step gear 382 is driven in the same second direction as the first offset step gear 382. In turn, rotation of the second offset step gear 384 drives rotation of the output gear 342 and the rotationally coupled sprocket 344 in a first direction.

The output gear 342 may be supported by the bottom bracket shaft 330. In some implementations, the output gear 342 is supported via a swivel bearing that does not transfer torque between the output gear 342 and the bottom bracket shaft 330. In contrast, the rotational bearing supporting the output gear 342 does not directly couple the rotation of the bottom bracket shaft 330 to the rotation of the output gear 342. This allows the output gear 342 to rotate (e.g., at a different speed than the bottom bracket shaft 330) relative to the bottom bracket shaft 330 under certain conditions and in certain embodiments. Under certain conditions, the bottom bracket shaft 330 may remain stationary during rotation of the output gear 342.

In some implementations, each of the output gear 342 and its supporting rotational bearing and the pedal output gear 336 and its supporting pedal unidirectional bearing 340 are coaxial with the bottom bracket axle 330. Each of these components, as well as sprocket 344, are configured to rotate about a first axis of rotation 338. The first and second offset step gears 382, 384 and the offset shaft 386 are configured to rotate about an offset rotation axis 388. Thus, the power path from the pedal crank 334 extends through the bottom bracket shaft, through the pedal one-way bearing 340 to the pedal output gear 336, through the first offset step gear 382 and the second offset step gear 384 to the output gear 342 and the sprocket 344.

Gearbox 300 may include a motor assembly that includes a motor 352 and a reduction component 354. Deceleration component 354 may be any suitable component or combination of components configured and arranged to provide an output angular velocity that is less than the angular velocity of motor 352. Deceleration component 354 may include one or more of a planetary gear set, a worm gear, a belt, a step gear, or any combination of these or other suitable components.

The motor assembly may include or be coupled to a motor one-way bearing (not specifically shown in fig. 8) that mechanically isolates the motor assembly 350 from the pedal crank 334. The motor one-way bearing may be located at any suitable location along the power path between the motor 352 and the first offset stepper gear 382.

The motor assembly 350 and the deceleration component 354 are configured to drive the first offset stepper gear 382 in a second direction when the motor 352 is driven. This also drives a second offset step gear 384 in a second direction, which in turn drives rotation of the output gear 342 and the rotatably coupled sprocket 344 in the first direction. However, further, rotation of the first offset step gear 382 in the second direction drives rotation of the pedal output gear 336 in the first direction. Rotation of the pedal output gear 336 and the outer race of the pedal one-way bearing 340 in the first direction does not result in corresponding rotation of the inner race of the pedal one-way bearing 340. Accordingly, the output gear 342 is driven to rotate in a first direction by the motor 352, while the bottom bracket axle 330 and the pedal crank 334 connected thereto may remain stationary because torque generated by the motor 352 is not transferred through the pedal one-way bearing 340 to the bottom bracket axle 330.

Fig. 9A to 14B

Fig. 9A shows a perspective view of another embodiment of a vehicle 10' including a pedal assembly and an alternative embodiment of a center drive unit including a motor configured to power the vehicle. Fig. 9B is a right side view of the vehicle of fig. 9A. Fig. 9C is a left side view of the vehicle of fig. 9A. Fig. 9D is a top view of the vehicle of fig. 9A.

The vehicle 10' of fig. 9A is similar to the vehicle 10 of fig. 1A and includes a transmission 400 mounted to a bottom bracket. In the illustrated embodiment, the bottom bracket axle 430 is located generally at the point where the down tube 42 'will intersect the seat tube 44'.

Fig. 10A shows a perspective view of the transmission of the vehicle of fig. 9A shown independent of the vehicle. Fig. 10B shows a right side view of the transmission of fig. 10A. Fig. 10C shows a left side view of the transmission of fig. 10A. FIG. 11A shows a perspective view of certain components of the transmission of FIG. 10A with the housing and certain additional components removed. FIG. 11B shows an exploded assembly view of the transmission components of FIG. 11A.

Fig. 12A shows a perspective view of the components of fig. 10A, wherein the components are moved relative to one another such that the axes of each rotational axis are substantially coplanar with one another. Fig. 12B shows a side view of the components of fig. 11A arranged as shown in fig. 12A. Fig. 12C shows a partial cross-sectional view of the components of fig. 11A arranged as shown in fig. 12A. FIG. 13A is a schematic illustration of components of the transmission of FIG. 10A.

Gearbox 400 includes a bottom bracket shaft 430 rotatably coupled to a pedal crank 434 on each end of bottom bracket shaft 430. Pedal output gear 436 is connected to bottom bracket shaft 430 via pedal one-way bearing 440, and output gear 442 is connected to bottom bracket 446 via swivel bearing 446. Pedal one-way bearing 440 conditionally couples pedal output gear 436 to bottom bracket shaft 430, and rotary bearing 446 supports output gear 442 on bottom bracket shaft 430 without directly rotationally coupling output gear 442 to bottom bracket shaft 430.

Gearbox 400 also includes a motor assembly 450 that includes a motor 452 and an output rotating element in the form of a motor output gear 456. In some implementations, because additional gear reduction stages are included in the power path from the motor 452, the planetary gear set may be omitted and/or the angular speed of the motor output gear 456 may be substantially equal to the output angular speed of the motor 452.

In other embodiments, the motor 452 may include an integrated deceleration component, such as a planetary gear system, within the housing of the motor 452 to reduce the angular velocity of the motor output gear 456 itself relative to the angular velocity of the motor 452, while increasing the output torque.

As with intermediate step gear set 160 of gearbox 100, gearbox 400 may include intermediate step gear set 460, which includes lower step gear 462 and upper step gear 464. The lower step gear 462 may be engaged with the motor output gear 456 of the motor assembly 400 and/or may have an effective radius that is greater than the effective radius of the upper step gear 464. However, unlike the intermediate step gear set 160 of the gearbox 100, in some implementations, the lower step gear 462 and the upper step gear 464 of the intermediate step gear set 460 are not conditionally rotationally coupled to each other via a one-way bearing. Instead, in certain variations, the lower and upper step gears 462, 464 are instead each coupled to a step gear shaft 472 that is coaxial with the upper and lower step gears 464, 462 and that extends through the upper and lower step gears 464, 462.

The upper step gear 464 is engaged with a motor drive gear 474 that is connected to an offset shaft 486 via a motor one-way bearing 470. The offset shaft 486 supports and is rotatably coupled to each of a first offset step gear 482 engaged with the pedal output gear 436 and a second offset step gear 484 engaged with the output gear 442.

As discussed above with respect to transmission 300, when a user rotates the pedal to drive bottom bracket axle 430 to move pedal crank 434 in a first direction, torque will be transferred from bottom bracket axle 430 to pedal output gear 436 via pedal one-way bearing 440. The pedal output gear 436 will be driven in a first direction and will in turn drive the first offset step gear 482 and the offset shaft 486 and the second offset step gear 484 in a second direction. The rotation of the second offset step gear 484 drives the output gear 442 engaged with the second offset step gear 484 to rotate in a first direction to enable power to be output via the sprocket 444. This power path is shown in fig. 13B as power path 490A.

However, due to the orientation of the motor one-way bearing 470, movement of the inner race of the motor one-way bearing 470 will not cause movement of the outer race of the motor one-way bearing 470, and the motor drive gear 474 will not be driven in the second direction. Intermediate step gear set 460 and other components along the power path between motor 452 and motor drive gear 474 will be isolated from the power provided by the rotation of pedal crank 434 by motor one-way bearing 470.

When the motor output gear 456 is driven in the second direction, the intermediate step gear set 460 is driven in a first direction opposite the second direction. In turn, the motor drive gear 474 is driven in the second direction by the intermediate step gear set 460. During rotation of the motor drive gear 474 in the second direction, the motor one-way bearing transfers torque to the offset shaft 486, causing the first offset step gear 482 and the second offset step gear 484 to be driven in the second direction along with the motor drive gear 474. The rotation of the second offset step gear 484 drives the output gear 442 engaged with the second offset step gear 484 to rotate in a first direction to enable power to be output via the sprocket 444. This power path is shown in fig. 13C as power path 490B.

In addition, rotation of the first offset step gear 482 drives rotation of the pedal output gear 436 engaged with the second offset step gear 484 in a first direction. However, when pedal output gear 436 is driven in the first direction, pedal one-way bearing 440 does not transfer torque to bottom bracket axle 430. Thus, due to the isolation provided by pedal one-way bearing 440, bottom bracket shaft 430 will not be affected by the operation of motor 452. Because crank 434 is not moved, the pedals may remain in a stable position so that a rider may place their feet on the pedals during motor drive operation of the vehicle.

Fig. 14A and 14B are perspective views showing the transmission of fig. 10A mounted to another embodiment of a vehicle. As can be seen in fig. 14A, the curved bracket 48 extending at least between the down tube 42 "and the seat tube 44" is sized and oriented to receive the gearbox 400 in a generally vertical orientation. The complementary shapes of the curved bracket 48 and the gearbox 400 will ensure alignment between the gearbox 400 and the curved bracket 48, and alignment between the apertures 92 in the curved bracket 48 and corresponding apertures 492 in the housing 410 of the gearbox 400.

In fig. 14B, it can be seen that the gearbox 400 has been housed within the curved bracket 48 and can be secured in place via any suitable method. For example, bolts or other fasteners may be inserted through apertures 92 in the curved bracket 48 into corresponding apertures 492 in the housing 410 of the gearbox 400. In other embodiments, the gearbox 400 may be secured in place via welding, adhesive, or any other suitable securing structure or method.

Certain additional aspects

In some embodiments, the gearing of the various gearboxes may be configured to drive the driven wheels of the vehicle at an angular speed of about 250 rpm. Conversely, in some embodiments, the motor may have an original output angular speed of about 18,000rpm, and the gearbox may be configured for the user to step at a speed of about 120 rpm. These angular velocities are one example of a wide range of suitable angular velocities for each of these components, but illustrate the relative amount of gear reduction that can be provided at various points in the power path of the illustrative gearbox described herein.

For example, in a gearbox such as gearbox 100, where the power path converges on output gear 142 and the angular velocity of output gear 142 is the same as the angular velocity of the pedal assembly, the motor power path may experience a total gear reduction between motor 152 and output gear 142 of approximately 150:1. For example, the planetary gear set 154 may provide approximately 7.2:1 gear reduction, the interface between the motor assembly output 156 and the intermediate gear set 160 may provide approximately 5:1 gear reduction, and the interface between the intermediate gear set 160 and the output gear 142 may provide approximately 4:1 gear reduction.

However, because the output gear 142 will be driven at about 120rpm and the driven wheel is intended to be driven at about 250rpm under the same conditions, the chain drive between the gearbox 100 and the rear wheel 30 may be configured to have a gear ratio of about 1:2, thereby approximately doubling the angular speed of the output gear 142 to achieve the desired angular speed of the driven wheel. In such an embodiment, this gear reduction and subsequent gear increase along the chain portion of the power path may affect the efficiency of the gearbox 100.

In contrast, since the power path of the gearbox 400 converges before the output gear 442 and the rotationally coupled sprocket 444, the sprocket 444 may be configured to be driven at the same angular velocity as the target angular velocity of the driven wheels. In such an embodiment, the motor power path may experience a total gear reduction of approximately 75:1 between the motor 452 and the output gear 442. For example, the interface between the motor assembly output gear 456 and the intermediate gear set 460 may provide a gear reduction of approximately 7.2:1, the interface between the intermediate gear set 160 and the motor drive gear 474 may provide a gear reduction of approximately 5:1, and the interface between the second offset step gear 484 and the output gear 442 may provide a gear reduction of approximately 2:1. The power path between pedal crank 434 and first offset step gear 482 may include a total gear speed increase of approximately 1:4. Because the chain portion of the power path does not include a gear increase, the transmission 400 may operate more efficiently than the transmission 100 under these illustrative conditions.

Although certain embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Further, various omissions, substitutions, and changes in the systems and methods described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope of the disclosure. Any feature from one embodiment may be included in any other embodiment. No element, feature, step or aspect is critical or essential.

Features, materials, characteristics or groups described in connection with a particular aspect, embodiment or example should be understood to apply to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not limited to the details of any of the foregoing embodiments. Protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Furthermore, although features may be described above as acting in certain combinations, one or more features can in some cases be excised from the claimed combination, and the combination may be directed to a subcombination or variation of a subcombination.

For the purposes of this disclosure, certain aspects, advantages and novel features are described herein. Not all of these advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the present disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as taught or suggested herein.

Certain terms

Certain terminology may be used in the following description for reference purposes only and is therefore not intended to be limiting. For example, terms such as "upper," "lower," "upward," "downward," "above," "below," "top," "bottom," "left," and the like refer to the directions in the drawings to which reference is made. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms "first," "second," and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context.

Conditional language such as "may," "may," or "may" are generally intended to convey that certain embodiments include, but other embodiments include, exclude certain features, elements, and/or steps unless specifically stated otherwise or otherwise understood in the context of use. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required by one or more embodiments or that one or more embodiments must include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment.

Conjunctive language such as the phrase "at least one of X, Y and Z" should be understood in the context of commonly used to express that the item, term, etc. may be X, Y or Z, unless explicitly stated otherwise. Thus, such connection language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

As used herein, terms relating to circular shape, such as diameter or radius, should be understood not to require a perfectly circular configuration, but rather should be applied to any suitable configuration having a cross-sectional area that can be measured from side to side. Terms generally associated with shape, such as "spherical" or "circular" or "cylindrical" or "semi-circular" or "semi-cylindrical" or any related or similar terms, do not need to conform exactly to the mathematical definition of sphere, circle, cylinder or other structure, but may contain rather close approximation structures.

The terms "about," "about," and "substantially" as used herein mean an amount approaching that amount which still performs the desired function or achieves the desired result. For example, in some embodiments, the terms "about," "about," and "substantially" may refer to an amount less than or equal to 10% of the amount, as the context allows. The term "consistent" as used herein means a value, quantity, or characteristic that substantially includes or is intended to be a particular value, quantity, or characteristic. As an example, in certain embodiments, the term "substantially parallel" may refer to something that deviates from exact parallelism by less than or equal to 20 degrees, as the context allows. As another example, in some embodiments, the term "substantially perpendicular" may refer to something that deviates from precisely perpendicular by less than or equal to 20 degrees, as the context allows.

The terms "comprising," "including," "having," and the like are synonymous and are used interchangeably in an open-ended fashion, and do not exclude additional elements, features, acts, operations, etc. Also, the terms "some," "some," and the like are synonymous and are used in an open-ended fashion. Furthermore, the terms "or" are used in its inclusive sense (rather than in its exclusive sense) such that, when used, for example, to connect a series of elements, the term "or" indicates one, some, or all of the elements in a list.

Some embodiments have been described in conjunction with the accompanying drawings. The drawings are to scale, but such scale is not limiting as dimensions and proportions other than those shown are contemplated and are within the scope of the disclosed invention. The distances, angles, etc. are merely illustrative and do not necessarily have an exact relationship to the actual size and layout of the devices shown. Components may be added, deleted, and/or rearranged. Furthermore, any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like disclosed herein in connection with various embodiments may be used in all other embodiments set forth herein. Additionally, any method described herein may be practiced using any device suitable for performing the recited steps.

Generally, the language of the claims should be construed broadly based on the language used in the claims. The language of the claims is not limited to the non-exclusive embodiments and examples shown and described in the present disclosure or discussed during prosecution of the application.

SUMMARY

Various embodiments and examples of mid-drive electric drive units and associated vehicles and methods have been disclosed herein. Although the invention has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the present disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the embodiments and certain modifications and equivalents thereof. The scope of the present disclosure is not intended to be limited by the specific disclosure of the preferred embodiments in this section or elsewhere in this specification, and may be defined by the claims set forth in this section or elsewhere in this specification or set forth in the future.

Claims (20)

1. A gearbox adapted for use with a mid-drive electric bicycle having pedals and driven wheels, the gearbox comprising:

a motor;

a plurality of gears;

a first one-way bearing; and

a second one-way bearing;

the first one-way bearing is configured to enable power from the motor to be transmitted to the driven wheel;

the second one-way bearing is configured to enable power from the foot pedal to be transmitted to the driven wheel; and is also provided with

The gearbox is configured to enable a user to drive the electric bicycle by: only through the foot pedal, only through the motor, and simultaneously through the foot pedal and the motor.

2. The gearbox of claim 1, wherein the gearbox comprises a sprocket configured to receive power from the motor and the foot pedal and transmit the power to the drive wheel via a chain.

3. The gearbox of claim 2 further comprising a bottom bracket shaft rotatably coupled to the foot pedal, wherein the sprocket is rotatably coupled to an output gear supported on the bottom bracket shaft.

4. A gearbox according to claim 3, wherein said output gear is conditionally rotationally coupled to said bottom bracket shaft by said second one-way bearing.

5. A gearbox according to claim 3 in which the output gear is supported on the bottom bracket shaft by a rotational bearing which allows the output gear to rotate independently of the bottom bracket shaft when not powered by the foot pedals.

6. The gearbox of any one of claims 2 to 5, wherein the plurality of gears comprises an intermediate step gear set forming part of a motor power path from the motor to the sprocket.

7. The gearbox of claim 6, wherein the intermediate step gear set comprises an upper step gear set conditionally rotationally coupled to a lower step gear set by the first one-way bearing.

8. The gearbox of any one of claims 1 to 7, wherein the gearbox forms part of a mid-drive unit axially offset from the axis of rotation of the driven wheels.

9. A bicycle, comprising:

A frame;

a driven wheel supported by the frame;

a pedal assembly;

a motor; and

a gearbox supported by the frame, the gearbox comprising:

a first one-way bearing forming part of a motor power path between the motor and an output gear operatively coupled to the driven wheel to transmit power thereto; and

a second one-way bearing forms part of a pedal power path between the pedal assembly and the output gear.

10. The bicycle of claim 9, wherein the pedal assembly comprises:

a bottom bracket axle extending through at least a portion of the gearbox; and

first and second pedal cranks rotatably coupled to the bottom bracket shaft at respective ends thereof.

11. The bicycle of claim 10, wherein the output gear is supported on the bottom bracket axle by the second one-way bearing.

12. The bicycle of claim 10, wherein the output gear is supported on the bottom bracket axle by a swivel bearing, the gearbox further comprising a pedal output gear supported on the bottom bracket axle by the second one-way bearing.

13. The bicycle of claim 12, wherein the first one-way bearing supports a motor drive gear on an intermediate shaft axially offset from the bottom bracket axle, the motor drive gear being operatively connected to the motor.

14. The bicycle of claim 13, wherein the intermediate shaft is rotatably coupled to a first offset gear engaged with the pedal output gear and a second offset gear engaged with the output gear.

15. The bicycle of claim 12 or 13 wherein the motor drive gear is operatively connected to the motor by an intermediate step gear set supported by a step gear shaft.

16. A gearbox configured to be secured to a bicycle frame, the gearbox comprising:

a sprocket configured to engage with a chain of the bicycle to transmit power to a drive wheel of the bicycle via the chain;

a bottom bracket axle configured to receive power from a pedal assembly of the bicycle;

a step gear configured to receive power from the motor;

a first one-way bearing forming at least a portion of a pedal power path between the bottom bracket shaft and an output gear operatively coupled to the sprocket; and

A second one-way bearing forms at least a portion of a motor power path between the step gear and the output gear operably coupled to the sprocket.

17. The gearbox of claim 16, wherein the output gear is supported on the bottom bracket shaft by the first one-way bearing.

18. The gearbox of claim 16, wherein the first one-way bearing and the output gear are supported on the bottom bracket shaft at different locations along the bottom bracket shaft.

19. A gearbox according to any of claims 16 to 18, wherein the step gear is supported on a step gear shaft by the second one-way bearing.

20. The gearbox of any one of claims 16 to 19, further comprising the motor positioned at least partially within a housing of the gearbox.