JP2026503505A - Geared continuously variable transmission - Google Patents

Abstract

Continuously variable transmissions for vehicles, particularly bicycles, assist users under a variety of conditions. The transmission combines the reliability and efficiency of gears with the ability to continuously and infinitely change the transmission's gear ratio. The transmission has a planetary gear arrangement with a sun gear that receives output torque through a carrier, a sun gear, and a ring gear. An electric motor engages the sun gear to continuously change the angular velocity of the sun gear, thereby continuously changing the transmission's gear ratio and increasing or decreasing the output torque at the ring gear. The ring gear rotates the bicycle's rear wheel, and the transmission provides a potentially infinite number of gear ratios to suit the user.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63/439,441, filed January 17, 2023, which is incorporated herein by reference in its entirety.

This disclosure relates to continuously variable transmissions, particularly for use on bicycles, that use gears to transfer power from the crankshaft to the rear hub so that the gear ratio of the transmission can be continuously varied through a potentially infinite number of gear ratios.

Bicycles typically have a drive chain and sprockets that transfer power from the crankshaft at the bicycle's bottom bracket to the rear wheel and tire at the bicycle's rear hub, which propels the bicycle. Power is equal to the product of torque and angular velocity; therefore, torque and angular velocity are inversely related for constant power. The gear ratio refers to the mechanical advantage gained by a transmission; the gear ratio is the output torque divided by the input torque, or the gear ratio is the input angular velocity divided by the output angular velocity. As explained here, the gear ratio can also be determined from the number of teeth on the sprockets or gears of a transmission.

Some bicycles have a single gear ratio between the bottom bracket sprocket and the rear hub sprocket, while some bicycles have multiple gear ratios between multiple sprockets on the crankshaft and/or multiple sprockets on the rear hub. While single gear ratio bicycles are generally inexpensive, simple, and reliable, a single gear ratio can only be optimized for a narrow range of conditions. A single gear ratio is one with a relatively large number of teeth on the rear hub sprocket, which increases the torque required to propel the bicycle from a standstill but limits the user's ability to ride the bicycle at high speeds. Conversely, a single gear ratio is one with a relatively small number of teeth on the rear hub sprocket, which increases the speed but limits the user's ability to initially propel the bicycle from a standstill.

Bicycles capable of multiple gear ratios typically have a derailleur that selectively moves the drive chain between sprockets on the bottom bracket and/or rear hub. Thus, a user can start with a gear ratio that provides more torque and helps propel the bicycle from a stationary position, and then the user can use the derailleur to move the drive chain to another sprocket to establish a gear ratio. This allows the user to further increase the speed of the bicycle, much like a car changes gears as it gains speed. However, with multiple gear ratios, the user is limited in the number of gear ratios they can choose from. These gear ratios are optimized only for specific operating conditions and may not be suitable for certain users.

Some bicycles have continuously variable transmissions with specialized components that continuously change the transmission's gear ratio over a potentially infinite number of ratios to suit every user's riding conditions. "Gear ratio" can refer to the use of sprockets or gears, but it can also refer generally to the mechanical efficiency of the transmission, even if the specialized components are not sprockets or gears. The specialized components might be a sheave-and-belt system, in which a belt connects a set of drive sheaves to a set of driven sheaves, and the sheaves change position to continuously change the transmission's gear ratio. Alternatively, the specialized components might be a disc-and-roller train of an annular continuously variable transmission. The discs transmit power between the drive and driven rollers, and the discs change position relative to the rollers to continuously change the transmission's gear ratio. Although these transmissions are continuously variable, the specialized components generally transmit power less efficiently than chain-and-sprocket or gear systems, or they are fragile and unreliable. Therefore, there is a trade-off between the efficiency of a sprocket or gear transmission and the practicality of a continuously variable transmission.

Another trend in bicycles is the growing popularity of electric bicycles, or "e-bikes," which brings additional considerations to transmissions. Specifically, e-bikes introduce many components to the bicycle frame, including the electric motor, controller, battery, and even transmission, combining the relatively high-speed, low-output torque of the electric motor with the relatively low-speed, high-torque requirements necessary for propelling the bicycle. Furthermore, some electric motors are located in the bottom bracket of e-bikes, with transmission components located in the rear hub. While sprockets, geared transmissions, and continuously variable transmissions are employed in the bicycle's rear hub, these transmissions also have the trade-offs mentioned above.

Embodiments of the present disclosure relate to a novel transmission for a bicycle rear hub that combines the efficiency of a sprocket or geared transmission with the utility of a continuously variable transmission. The disclosed transmission uses an outer planetary gearing to transfer power from a drive sprocket to the rear wheel and tire to propel the bicycle. Furthermore, the transmission uses an electric motor to continuously vary the speed of the sun gear of the outer planetary gearing, thereby continuously varying the gear ratio of the transmission over a potentially infinite number of values. Thus, the disclosed transmission uses gears to vary the gear ratio between the drive sprocket and the rear wheel and tire over a potentially infinite number of ranges. While embodiments of the present disclosure are described with respect to bicycles, it will be understood that the disclosure encompasses embodiments directed to other vehicles or any device that benefits from using gears to continuously and infinitely change gear ratios.

One aspect of embodiments of the present disclosure is to provide a transmission that transfers power from a user's pedaling action to the rear wheel and tire using an efficient gear derailleur. In some embodiments, the user operates the pedals to rotate the crankshaft, which rotates the drive chain and drive sprocket at the rear hub. While the present disclosure includes embodiments with only one sprocket at the bottom bracket and one at the rear hub, it will be understood that the present disclosure also includes embodiments with multiple sprockets at the bottom bracket and/or rear hub. The drive sprocket rotates the carrier of the outer planetary gear set, which rotates the outer planetary gear relative to the sun gear. This action rotates a ring gear connected to a housing in the rear hub. Rotation of the housing rotates the rear wheel and tire, propelling the bicycle. In a first operating mode, the sun gear causes the transmission to have a gear ratio determined by the configuration and number of teeth of the outer planetary gear set's components.

A further aspect of an embodiment of the present disclosure is to provide a transmission that selectively rotates the sun gear to continuously change the gear ratio of the transmission. In a second operating mode, the electric motor rotates the sun gear to change the relative speed of the carrier and sun gear. As a result, the outer planetary gears continue to drive the ring gear and housing, but at different gear ratios, torque increases at the ring gear and housing. The electric motor can rotate the sun gear at any angular speed within a range, thereby allowing for continuous and infinitely variable gear ratio changes.

Another aspect of an embodiment of the present disclosure is to provide a transmission with an inner planetary gear set that transfers power from an electric motor to a sun gear of a planetary gear set. The output of the electric motor is relatively high speed and low torque, while other components of the transmission rotate relatively slow speed and high torque. To bridge this gap, an output pinion on the output shaft of the electric motor is disposed within and meshes with multiple inner planetary gears, each of which rotates about a pin extending into a fixed shaft. In this sense, the "carrier" of the inner planetary gear set is the fixed shaft. The inner planetary gear is then disposed on the inner surface of the sun gear and meshes with its teeth. The sun gear therefore serves as both the sun gear of the outer planetary gear set and the ring gear of the inner planetary gear set. By including the inner planetary gear set, the output of the sun gear is slower and has higher torque than the input of the electric motor.

One aspect of an embodiment of the present disclosure is to provide a one-way clutch between the sun gear and the fixed axle of the transmission to restrict rotation of the sun gear to only one direction. As described herein, in a first operating mode, the sun gear is fixed and does not rotate relative to the axle. In a second operating mode, the sun gear rotates in one direction relative to the axle, continuously changing the gear ratio of the transmission. To accomplish this, a ratchet wheel connects to the inner surface of the sun gear, and a pawl system is used as the one-way clutch, with the ratchet wheel having teeth that protrude inward from the inner surface of the ratchet wheel. A deflecting pawl protrudes from the axle and engages with the teeth of the ratchet wheel, allowing the sun gear to rotate in only one direction relative to the axle.

One aspect of an embodiment of the present disclosure is to provide a controller that communicates with a battery and an electric motor to determine when and how the electric motor moves a sun gear to continuously change the gear ratio of a transmission. The controller selectively allows the battery to transfer power to the electric motor based on one or more input signals from one or more input devices. The input devices are devices that detect characteristics or performance of the transmission, such as the angular velocity of the carrier of the outer planetary gear set. The input devices may also be buttons or levers that a user operates to set pedal assist level, output torque, RPM, etc. The one or more input devices send input signals to the controller, which determines when and how the battery transfers power to the electric motor. "When" the controller allows the battery to transfer power to the electric motor is determined by the controller based on, for example, conditions or thresholds from the input signals or values derived from the input signals. "How" the controller allows the battery to transfer power to the electric motor is the manner in which power is transferred, for example, at a constant or variable amperage. The controller makes the decision to transmit current at a constant or variable amperage based on conditions or thresholds.

A first aspect of the present disclosure provides a continuously variable transmission for a vehicle, the continuously variable transmission for a vehicle comprising: a carrier configured to receive input torque; a plurality of outer planetary gears rotatably engaged with the carrier; and a sun gear disposed within and engaged with the plurality of outer planetary gears, the sun gear being selectively rotatable and comprising a ring gear disposed around and engaged with the plurality of outer planetary gears; in a first operating mode operated by input torque, the sun gear is stationary, and the carrier and the plurality of outer planetary gears are configured to drive the ring gear with a first output torque; and in a second operating mode operated by input torque, the sun gear rotates in the same direction as the carrier, and the carrier and the plurality of outer planetary gears are configured to drive the ring gear with a second output torque greater than the first output torque.

The continuously variable transmission of the first aspect may optionally include an electric motor that engages with the sun gear to selectively rotate the sun gear.

A first aspect of the continuously variable transmission includes one or more of the above-described embodiments, and optionally includes a plurality of internal planetary gears disposed within and engaging with the sun gear, and an output pinion of the electric motor disposed within and engaging the plurality of internal planetary gears to transmit motor torque from the electric motor to the sun gear and selectively rotate the sun gear.

A first aspect of the continuously variable transmission includes one or more of the above-described embodiments, and optionally includes a ratchet wheel connected to the inner surface of the sun gear, a drive shaft disposed within the ratchet wheel, and a deflection pawl disposed on the drive shaft, the deflection pawl configured to selectively engage with the ratchet wheel so that the sun gear rotates in only one direction relative to the drive shaft.

A first aspect of the continuously variable transmission includes one or more of the above-described embodiments and optionally includes a drive sprocket that engages with the carrier via a one-way clutch, and transmits input torque to the carrier when the drive sprocket rotates in only one direction relative to the carrier.

A first aspect of the continuously variable transmission includes one or more of the above-described embodiments, and optionally includes a housing in which the sun gear, the plurality of outer planetary gears, and the carrier are at least partially disposed, and a ring gear is connected to an inner surface of the housing such that the housing receives a first output torque and a second output torque.

The continuously variable transmission of the first aspect includes one or more of the above-described embodiments, and optionally, the housing is configured to receive at least one spoke of a wheel, such that rotation of the housing rotates the wheel.

A second aspect of the present disclosure provides a continuously variable transmission for a vehicle, the continuously variable transmission for a vehicle comprising: a ring gear configured to receive an output torque; a plurality of outer planetary gears disposed within and engaged with the ring gear; the plurality of outer planetary gears configured to receive a first input torque; a sun gear disposed within and engaged with the plurality of outer planetary gears; and an electric motor engaged with the sun gear and selectively rotating the sun gear with a second input torque, the output torque being proportional to the first input torque and the second input torque, and the electric motor continuously varying the gear ratio between the output torque and the first input torque.

The second aspect of the continuously variable transmission optionally includes a carrier connected to the plurality of outer planetary gears, the carrier configured to receive a first input torque and transmit the first input torque to the plurality of outer planetary gears.

A second aspect of the continuously variable transmission includes one or more of the above-described embodiments, and optionally further includes a shaft, with the sun gear engaging the shaft via a one-way clutch such that the sun gear rotates in only one direction relative to the shaft.

A second aspect of the continuously variable transmission includes one or more of the above-described embodiments and optionally includes a drive sprocket that engages with the carrier via a one-way clutch, and the drive sprocket transmits a first input torque to the carrier only when the drive sprocket rotates in one direction relative to the carrier.

A second aspect of the continuously variable transmission includes one or more of the above-described embodiments and optionally includes a controller in communication with the electric motor, the controller configured to receive an input signal, and the controller configured to cause the electric motor to rotate the sun gear based on the input signal.

A second aspect of the continuously variable transmission includes one or more of the above-described embodiments and optionally includes an input device in communication with the controller, the input device configured to transmit an input signal to the controller based on the input signal.

A second aspect of the continuously variable transmission includes one or more of the above-described embodiments and optionally includes a battery in communication with a controller, the controller configured to cause the battery to transfer power to the electric motor.

A third aspect of the present disclosure provides a continuously variable transmission for a vehicle, the continuously variable transmission for a vehicle comprising a first shaft and a second shaft configured to be fixed to the vehicle, the first shaft having an opening, an electric motor fixed to the first shaft and configured to receive power through the opening of the first shaft, a sun gear having a ring gear, a plurality of outer planetary gears disposed within and engaged with the ring gear, and a sun gear disposed within and engaged with the plurality of outer planetary gears, the sun gear engaged with the second shaft via a one-way clutch such that the sun gear rotates in only one direction relative to the second shaft, and the electric motor configured to rotate the sun gear in one direction relative to the second shaft at a varying angular velocity and vary the gear ratio between the ring gear and a carrier connected to the plurality of outer planetary gears.

The third aspect of the continuously variable transmission optionally includes a plurality of inner planetary gears rotatably connected to the second shaft, the plurality of inner planetary gears being disposed within the sun gear and engaging with the sun gear, and an output pinion of the electric motor being disposed within the plurality of inner planetary gears and engaging with the plurality of inner planetary gears to rotate the plurality of inner planetary gears and the sun gear.

A third aspect of the continuously variable transmission includes one or more of the above-described embodiments, and optionally, the output pinion is connected to an output shaft of the electric motor, and a bearing disposed within a partition wall of the housing supports the output shaft of the electric motor.

A third aspect of the continuously variable transmission includes one or more of the above-described embodiments, and optionally, the plurality of outer planetary gears includes four outer planetary gears and the plurality of inner planetary gears includes three inner planetary gears.

A third aspect of the continuously variable transmission includes one or more of the above-described embodiments, and optionally includes a housing at least partially enclosing the electric motor and the planetary gear set, a first bearing disposed between the housing and the first shaft to allow the housing to rotate about the first shaft, and a second bearing disposed between the housing and the carrier to allow the housing to rotate about the carrier.

A third aspect of the continuously variable transmission includes one or more of the above-described embodiments and optionally includes a controller in communication with the electric motor, the controller configured to receive an input signal, and the controller configured to cause the electric motor to rotate the sun gear based on the input signal.

As used herein, the terms "at least one," "one or more," and "and/or" are open-ended expressions that function both conjunctively and disjunctively. For example, "at least one of A, B, and C," "at least one of A, B, or C," "one or more of A, B, and C," "one or more of A, B, or C," and "A, B, and/or C" mean A only, B only, C only, A and B, A and C, B and C, or A, B, and C.

Unless otherwise specified, all numerical values expressing quantities, dimensions, conditions, etc. used in this specification and claims should be understood to be modified in all cases by the word "about."

As used herein, the terms "a" or "an" refer to one or more of that entity. Thus, the terms "a" (or "an"), "one or more," and "at least one" are used interchangeably herein.

The use of "comprises," "has," or "comprises," and derivatives thereof herein is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Thus, the words "comprises," "comprises," or "has," and derivatives thereof, are used interchangeably herein. The use of "engages" and derivatives thereof herein is meant to encompass either a direct or indirect connection between elements.

As used herein, the term "means" should be understood to be interpreted as broadly as possible pursuant to 35 U.S.C. §112(f). Accordingly, any claim containing the term "means" encompasses all structure, material, or acts described herein, and all equivalents thereof. Furthermore, structures, materials, or acts, and equivalents thereof, include everything described in the Summary, Brief Description of the Drawings, Detailed Description, Abstract, and the claims themselves.

These and other advantages are apparent from the disclosure of the invention contained herein. The above-described embodiments, objects, and configurations are not complete or exhaustive. This Summary of the Invention is not intended to, and should not be construed as, representing the entire scope of the invention. Furthermore, references herein to "the invention" or aspects thereof should be understood to refer to several embodiments of the invention and should not necessarily be construed as limiting all embodiments to the particular description. The invention is described at various levels in the Summary of the Invention, the accompanying drawings, and the Detailed Description, and the inclusion or non-inclusion of elements, parts, etc. in the Summary of the Invention is not intended to limit the scope of the invention. Additional aspects of the invention will be more readily apparent from the Detailed Description, particularly when taken in conjunction with the drawings.

It should be understood that any feature or aspect described herein may be claimed in combination with any other feature or aspect described herein, whether or not from the same embodiment.

One or more aspects described herein may be combined with one or more other aspects described herein. One or more features described herein may be combined with one or more other features described herein. One or more embodiments described herein may be combined with one or more other embodiments described herein.

Those skilled in the art will appreciate that the following description is merely illustrative of the principles of the present disclosure, which may be applied in various ways to provide many different alternative embodiments. This description is made to illustrate the general principles of the teachings of the present disclosure and is not meant to limit the inventive concepts disclosed herein.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments and, together with the general description of the invention given above and the detailed description of the drawings given below, serve to explain the principles of the invention.
FIG. 1 is a perspective view of a bicycle frame and rear hub according to one embodiment of the present disclosure. FIG. 1B is a perspective view of the rear hub of FIG. 1A according to one embodiment of the present disclosure. FIG. 1B is a cross-sectional bottom view of the rear hub taken along line BB in FIG. 1A according to one embodiment of the present disclosure. FIG. 3 is an exploded perspective view of the electric motor and associated components shown in FIG. 2 according to one embodiment of the present disclosure. FIG. 3 is an exploded perspective view of the inner planet gear and associated components shown in FIG. 2 according to one embodiment of the present disclosure. FIG. 3 is an exploded perspective view of the outer planet gear and associated components shown in FIG. 2 according to one embodiment of the present disclosure. FIG. 1B is a cross-sectional bottom view of the rear hub taken along line BB in FIG. 1A according to one embodiment of the present disclosure. FIG. 7 is a cross-sectional elevation view of the inner and outer planetary gears and associated components taken along line CC in FIG. 6 according to one embodiment of the present disclosure. FIG. 7 is a cross-sectional elevation view of the one-way clutch and associated components taken along line DD in FIG. 6 according to one embodiment of the present disclosure. FIG. 2 is a schematic diagram of a controller and related elements according to one embodiment of the present disclosure.

It should be understood that the drawings are not necessarily drawn to scale and may be resized in various ways. In some embodiments, details that are not necessary for an understanding of the invention or that make other details difficult to understand have been omitted. It should, of course, be understood that the invention is not necessarily limited to the particular embodiments disclosed herein.
2 Bicycle frame 4 Rear hub 6 Brake shaft 8 Drive shaft 10 Drive sprocket 12 Housing 14 Spoke holes 16 Brake disc 17 Derailleur 18a First housing part 18b Second housing part 20 Brake fastener 22 Brake bearing 24 Brake bracket 26 Electric motor 28 Mount 30 Mount fastener 32 Brake shaft opening 34 Partition wall 36 Output bearing 38 Output pinion 40 Inner planetary gear 42 Sun gear 44 Ratchet wheel 46 Retaining ring 48 Outer planetary gear 50 Outer planetary gear bearing 52 Outer planetary gear pin 54 Washer 56 Ring gear 58 Carrier 60 Drive shaft bearing 62 Sun gear bearing 64 Carrier bearing 66 Output shaft 68 Nut 70 Inner planet gear bearing 71 Output pinion teeth 72 Inner planet gear pin 73 Inner planet gear teeth 74 Pawl 75 Pawl system 76 Pawl spring 77 Sun gear teeth (outer surface)
78 Retaining ring 79 Outer planetary gear teeth 80 One-way clutch 81 Ring gear teeth 82 First input torque 83 Sun gear teeth (inner surface)
84 Second input torque 85 Inner planetary gear set 86 Output torque 87 Outer planetary gear set 88 Counterclockwise side 90 Clockwise side 92 Input device 94 Controller 96 Battery

Detailed Description of the Invention

While the following text is a detailed description of numerous different embodiments, it should be understood that the legal scope of that description is defined by the language of the claims at the end of this disclosure. The detailed description is to be construed as exemplary only and does not describe every possible embodiment, as describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments, using current technology or technology developed after the filing date of this patent application, are contemplated and are within the scope of the claims. Furthermore, combinations of features shown in the various figures may be used to create additional embodiments of the present disclosure. Thus, the dimensions, aspects, and features of one embodiment of the transmission can be combined with the dimensions, aspects, and features of other embodiments of the transmission to create the claimed embodiments.

Figure 1A shows a bicycle frame 2 with a rear hub 4, and Figure 1B shows another view of the rear hub 4 of the present disclosure. As with a typical bicycle, including an electric bicycle or e-bike, a user pedals to rotate a crankshaft, which transmits power to the rear hub 4 via a drive chain. As the rear hub 4 rotates, the wheel and tire connected to the rear hub 4 also rotate, propelling the bicycle.

As shown in FIG. 1B, the rear hub 4 includes a brake shaft 6 and an opposing drive shaft 8. These shafts 6, 8 are secured to portions of the bicycle frame 2 with nuts or other fasteners. The drive sprocket 10 receives power from the drive chain, which transmits power through the derailleur to rotate the housing 12 and propel the bicycle. The housing 12 encloses at least some of the derailleur components and has a plurality of spoke holes 14 arranged around the periphery of the housing 12. The spokes of the wheel extend through the spoke holes 14, transmitting the rotation of the housing 12 to the wheel and its associated tire, propelling the bicycle. Additionally, FIG. 1B shows a brake disc 16, which engages a brake component to stop the housing 12 from rotating relative to the bicycle frame 2 and thus stopping the bicycle. Line B-B is shown in FIG. 1A.

2 shows a cross-sectional bottom view of the rear hub 4 taken along line B-B in FIG. 1A. Specifically, FIG. 2 shows the components of the derailleur 17 that transfer power from the drive sprocket 10 to the housing 12. The term "derailleur" can be used interchangeably with the term "rear hub" and can also refer to the components of the "rear hub" that transfer power. The housing 12 includes a first portion 18a and a second portion 18b that are interconnected. In some embodiments, the housing 12 is a single, continuous structure, while in other embodiments, the housing 12 includes three or more portions joined together. At least one fastener 20 connects the brake disc 16 to the first portion 18a of the housing 12, and a brake bearing 22 allows the housing 12 to rotate relative to the brake shaft 6. As described herein, the brake shaft 6 is coupled to the bicycle frame 2, which may include a brake bracket 24 mounted with a brake element that engages the brake disc 16.

The transmission 17 includes an electric motor 26 that can selectively and infinitely change the gear ratio of the transmission 17. The electric motor 26 is disposed within the housing 12 and connected to a mount 28. The mount 28 is secured to the brake shaft 6 by a fastener 30. The brake shaft 6 has an opening 32 through which power can be transmitted from an external power source, such as a battery, to the space within the housing 12 and to the electric motor 26. Because the electric motor 26 is secured to the brake shaft 6, many parts of the electric motor 26 do not rotate relative to the bicycle frame 2. The electric motor 26 may be a DC motor, an AC motor, a servo motor, or any other motor that converts electric power into physical motion.

The bulkhead 34 supports the housing 12 across the space within the housing 12 and also supports the output shaft (66 in FIG. 3) of the electric motor 26. Specifically, an output bearing 36 is disposed between the bulkhead 34 and the output shaft of the electric motor 26, allowing the output shaft to rotate relative to the bulkhead 34. As the output shaft of the electric motor 26 rotates, the output shaft rotates an output pinion 38, which drives multiple internal planetary gears 40 via gear teeth, and the internal planetary gears 40 drive a sun gear 42 via gear teeth. In some embodiments, the internal planetary gears 40 rotate about a bearing (70 in FIG. 4) and pin (72 in FIG. 4) of the drive shaft 8, which does not rotate relative to the bicycle frame 2. Additionally, several components interact with the sun gear 42 to transmit power through the transmission 17 and enable continuous, infinitely variable gear ratios. One end of the drive shaft 8 is disposed within and engages the sun gear 42 via a pawl system (75 in FIG. 4) that functions as a one-way clutch. Specifically, a ratchet wheel 44 with asymmetrical teeth is connected to the inner surface of the sun gear 42. As described herein, a pawl system has deflecting teeth that engage with the teeth of the ratchet wheel 44, causing the sun gear 42 to rotate in only one direction relative to the drive shaft 8. A retaining ring 46 holds the pawl system components to the drive shaft 8.

A plurality of outer planetary gears 48 are then disposed around the sun gear 42 and engage with it via gear teeth. Each outer planetary gear 48 is rotatable around a bearing 50 and a pin 52 extending into a carrier 58. A washer 54 is disposed around each pin 52 adjacent to the carrier 58 to distribute forces and hold the components in place. A ring gear 56 is disposed around the plurality of outer planetary gears 48 and engages with them via gear teeth. The ring gear 56 is connected to the inner surface of the housing 12, so that power transmitted to the ring gear 56 is also transmitted to the housing 12, propelling the bicycle. The carrier 58 receives power from the drive sprocket 10 via a one-way clutch (80 in FIG. 6) or freewheel. The drive sprocket 10 transmits power to the carrier 58 only when the drive sprocket 10 rotates in one direction relative to the carrier 58. The one-way clutch allows the drive chain, bottom bracket sprocket, and drive sprocket 10 to transmit power when the user pedals in a forward direction. However, as with some existing bicycles, the one-way clutch prevents power transmission when the user pedals in a reverse direction. It will be understood that the one-way clutch is optional, and in embodiments without a one-way clutch, the user would need to pedal in the opposite direction to reverse the motion of the bicycle.

The drive shaft bearing 60 is disposed between the carrier 58 and the drive shaft 8 so that the carrier 58 can rotate relative to the drive shaft 8. The sun gear bearing 62 is disposed between the carrier 58 and the sun gear 42 so that the carrier 58 can rotate relative to the sun gear 42. The carrier bearing 64 is disposed between the housing 12 and the carrier 58 so that the housing 12 can rotate relative to the carrier 58, and therefore relative to the drive shaft 8.

Figures 3-5 show exploded views of the various components in Figure 2. Figure 3 is an exploded perspective view of the electric motor 26 and related components. Fasteners 20 secure the brake disc 16 to the first portion 18a of the housing, and nuts 68 secure the brake shaft 6 to the frame of the bicycle or other vehicle. Brake bearings 22 allow the housing to rotate relative to the brake shaft 6. The electric motor 26 is secured to a mount 28, which is secured to the brake shaft 6 by fasteners 30. The electric motor 26 has an output shaft 66 that rotates when the electric motor 26 is powered. A bulkhead 34 traverses the housing and supports the electric motor output shaft 66. The output bearing 36 allows the output shaft 66 to rotate relative to the bulkhead 34.

FIG. 4 shows an exploded perspective view of the inner planetary gear 40 and associated components. As described herein, the output shaft of an electric motor rotates the output pinion 38, which is fixed to the output shaft. The output pinion 38 has teeth 71 that rotate teeth 73 on the inner planetary gear 40 of the inner planetary gear set (85 in FIG. 7). The inner planetary gear 40 rotates about a pin 72 and a bearing 70 that extends within the drive shaft 8. The drive shaft 8 is fixed to the bicycle and does not rotate relative to the bicycle frame (2 in FIG. 1). The drive shaft bearing 60 allows the carrier of the outer planetary gear set (87 in FIG. 7) to rotate relative to the drive shaft 8. Additionally, components of the pawl system 75 restrict rotation of the sun gear to only one direction. In this embodiment, three pawls 74 and respective pawl springs 76 are positioned within the drive shaft 8 by a retaining ring 78. The pawls 74 engage the ratchet wheel so that the ratchet wheel and sun gear can rotate in only one direction relative to the drive shaft 8. It will be understood that the present disclosure encompasses embodiments with other types of one-way clutch or pawl systems 75, different numbers of pawls 74, biasing members other than pawl springs, springs 76 having linear or non-linear responses, etc.

Figure 5 shows an exploded perspective view of the outer planetary gears 48 and associated components. The drive sprocket 10 selectively rotates the carrier 58, which in turn drives the multiple outer planetary gears 48. The outer planetary gears 48 are rotatably connected to the carrier 58 via bearings 50, pins 52, and washers 54. The outer surface of the sun gear 42 has teeth 77 that rotate relative to teeth 79 on the outer planetary gears 48, and the ratchet wheel 44 is fixed to the inner surface of the sun gear 42 as described herein. In some embodiments, the sun gear 42 and ratchet wheel 44 are of unitary construction. The teeth 79 on the outer planetary gears 48 rotate relative to teeth 81 on the ring gear 56, which is fixed to the inner surface of the second portion 18b of the housing. The sun gear bearings 62 allow the carrier 58 to rotate relative to the sun gear 42, and the carrier bearings 64 allow the housing to rotate relative to the carrier 58 and drive shaft.

The various gear ratios can be seen from the components shown in Figures 3 to 5. Starting with the outer planetary gear set (87 in Figure 7), since the sun gear 42 is stationary in the first mode of operation, the gear ratio of the outer planetary gear set is expressed as follows:

where N _Ring is the number of teeth on the ring gear 56 and N _Sun is the number of teeth on the outer surface of the sun gear 42. In some embodiments, the number of teeth on the ring gear 56 is approximately 90-100, and the number of teeth on the outer surface of the sun gear 42 is approximately 38-45. Therefore, in a first operating mode in which the sun gear 42 is fixed, the gear ratio and overall transmission ratio of the outer planetary gear set is approximately 1:1.3 to 1:1.6. Therefore, in a second operating mode in which the electric motor increases the output torque of the ring gear 56 through the sun gear 42, the gear ratio, or mechanical gain, between the drive sprocket 10 and the ring gear 56 increases to a larger value, such as 1:1 or 2:1 or more. In this second operating mode, the gear ratio of the outer planetary gear set is expressed as:

For the inner planetary gear set (85 in FIG. 7), since the inner planet gear rotates about a fixed axis and the "carrier" is substantially stationary, the gear ratio of the inner planet gear is expressed as:

where N _SI is the number of teeth on the inner surface of the sun gear 42 and N _OP is the number of teeth on the output pinion 38. In some embodiments, the number of teeth on the inner surface of the sun gear is approximately 75-85 and the number of teeth on the output pinion 38 is approximately 10-15. Thus, the gear ratio of the inner planetary gear set is approximately -8.5:1 to -5:1.

6-8 illustrate the operation of the components of the transmission 17, which allow the transmission 17 to efficiently transfer power through the gear teeth and to continuously and infinitely change the gear ratio of the transmission 17. FIG. 6 is another cross-sectional bottom view of the rear hub 4 and transmission 17, showing the first power input 82, the second power input 84, and the power output 86. The power output 86 of the ring gear 56, which rotates the housing 12 and propels the bicycle, is equal to the sum of the first power input 82 from the drive sprocket 10 and the second power input 84 from the electric motor 26. This can be expressed as:

where _P0 is the output power, _P1 is the first input power from the drive sprocket 10, and _P2 is the second input power from the electric motor 26. Because power is the product of torque and angle, Equation 4 above can be rewritten as follows:

where T is torque and ω is angular velocity. These torques and angular velocities are generated by specific components of the transmission 17. Specifically, the component related to the power output is the ring gear 56 because the ring gear 56 rotates the housing 12 and the rear wheels and tires. The component related to the first power input is the carrier 58 because the user provides power to the drive rocket 10 and the carrier 58. The component related to the second power input is the sun gear 42 because the electric motor 26 provides power to the movement of the sun gear 42. Therefore, Equation 5 above can be rewritten as follows:

Here, "Ring" is ring gear 56, "Carrier" is carrier 58, and "Sun" is sun gear 42. Rewriting equation 6 above for the output torque at ring gear 56, which rotates housing 12 and propels a vehicle such as a bicycle, yields the following equation:

Using this equation 7 for the output torque of ring gear 56, transmission 17 generally has two modes of operation. In the first mode of operation, no power is supplied to electric motor 26, and therefore the output shaft of electric motor 26 does not rotate. As a result, inner planetary gear set 40 does not rotate, and sun gear 42 does not rotate due to the one-way clutch described herein with respect to FIG. 8. With no power, torque, or angular velocity from the electric motor and sun gear 42, equation 7 above simplifies to:

Thus, drive sprocket 10 rotates carrier 58, which drives outer planetary gears 48 relative to stationary sun gear 42. Outer planetary gears 48 then rotate ring gear 56 and housing 12 with an output torque T _ring according to Equation 8 above. The gear ratio can be expressed as the angular velocity of carrier 58 divided by the angular velocity of ring gear 56. For a gear ratio of 0.77 as shown in Equation 1, Equation 8 becomes:

This operating mode represents a low torque and high speed output at the ring gear 56. This is suitable for a moving vehicle or for users attempting to reach high speeds.

In the second operating mode, the electric motor 26 is powered, rotating the output shaft to increase the output torque _Tring . This rotates the inner planetary gear 40, which in turn rotates the sun gear 42. As the sun gear 42 moves and the carrier 58 rotates the outer planetary gear 48, the outer planetary gear 48 pushes the moving sun gear 42, rather than the stationary sun gear 42. According to Equation 7, the resulting increase in output torque _Tring results. As the electric motor 26 rotates the output shaft, torque increases and the RPMs decrease at the ring gear 56. This is appropriate for a stationary or slow-moving vehicle. Because the electric motor 26 can continuously change the angular velocity of the sun gear 42 from stationary to high angular velocities, the relative speed between the carrier 58 and the sun gear 42 changes continuously, and the gear ratio changes continuously and infinitely to increase the output torque _Tring . The one-way clutch 80 or freewheel is optional; in embodiments without the one-way clutch 80, the user can reverse the bicycle's motion by pedaling in the opposite direction.

Using the above equation, the operation of the transmission 17 can be expressed in terms of torque. For example, in a first mode, the user supplies an input torque to the carrier 58, generating a first output torque at the ring gear 56. Then, in a second mode, in which the electric motor 26 rotates the sun gear 42, the user supplies the same input torque to the carrier 58. This causes the ring gear 56 to generate a second output torque greater than the first input torque, due to the continuously and infinitely variable gear ratio between the ring gear 56 and the carrier 58 of the transmission 17. Similarly, the operation of the transmission 17 can be described in terms of the output torque at the ring gear 56 being proportional to the first input torque from the user at the carrier 58 and the second input torque from the electric motor 26 at the sun gear 42. Because the electric motor 26 can continuously and infinitely vary the second input torque, the gear ratio between the output torque and the first input torque changes continuously and infinitely. Figure 6 shows the cut lines C-C and D-D.

7 is a cross-sectional elevation view of components of the transmission 17 taken along line CC in FIG. 6. This view illustrates the movement of components in different operating modes. In the first mode, the inner planetary gear set 85 does not rotate. Specifically, the electric motor receives no power, the output shaft 66 does not rotate, the output pinion 38 connected to the output shaft 66 does not rotate, the inner planetary gear 40 engaged with the output pinion 38 does not rotate, and therefore the sun gear 42 does not rotate. When the user pedals, turning the drive chain and drive sprocket, the outer planetary gear set 87 rotates. Specifically, the carrier 58 rotates counterclockwise, rotating the outer planetary gear 48, which in turn pushes against the stationary sun gear 42. The pawl system (75 in FIG. 8), which functions as a one-way clutch, prevents the sun gear 42 from rotating clockwise and remains stationary. The outer planetary gears 48 rotate counterclockwise about their respective pins, which causes the ring gear 56 and housing 12 to rotate counterclockwise, propelling the bicycle. The output torque of the ring gear 56 is determined according to Equation 8.

In the second mode, the electric motor receives power and the output shaft 66 rotates clockwise. This causes the output pinion 38 to also rotate clockwise and the inner planetary gear 40 to rotate counterclockwise. The teeth (73 in FIG. 4) on the inner planetary gear 40 rotate the teeth 83 on the inner surface of the sun gear 42, which causes the sun gear 42 to rotate counterclockwise, i.e., in the direction permitted by the pawl system shown in FIG. 8. As previously described, the movement of the sun gear 42 increases the output torque _Tring . The electric motor can continuously change the angular velocity of the output shaft 66, thus continuously and infinitely varying the gear ratio and increasing the output torque _Tring of the transmission 17.

It will be appreciated that the present disclosure encompasses embodiments of transmission 17 in which the electric motor can rotate output shaft 66 in either direction to increase or decrease output torque _Tring . A decrease in output torque _Tring results in an increase in output angular velocity _ωring , which is more suitable for a bicycle or vehicle already in motion.

It will further be appreciated that the present disclosure encompasses embodiments of the transmission 17 in a first operating mode in which the stationary sun gear 42 exerts a high torque, low speed output on the ring gear 56. By reversing the pawl system and reversing the rotation of the electric motor output shaft, the movement of the sun gear 42 caused by the electric motor continuously and infinitely changes the gear ratio, reducing torque and increasing the angular velocity output of the ring gear 56.

Figure 8 shows a cross-sectional elevation view of the pawl system 75, which functions as a one-way clutch, taken along line D-D in Figure 6. The pawl system 75 restricts rotation of the sun gear 42 to only one direction relative to the drive shaft 8. As described herein, the ratchet wheel 44 is described as part of the pawl system 75 and is connected to the inner surface of the sun gear 42. The ratchet wheel 44 has inwardly extending teeth on the inner surface of the ratchet wheel 44 that are asymmetrical, with one tooth being longer than the other. As shown in Figure 8, the counterclockwise side 88 of the teeth is longer than the teeth on the clockwise side 90 of the teeth, such that the clockwise side 90 of the teeth forms a larger angle with respect to the inner surface of the ratchet wheel 44 than the counterclockwise side 88.

A portion of the pawl system 75 is disposed on the outer surface of the drive shaft 8 and engages the ratchet wheel 44. The pawl system 75 includes at least one pawl 74 biased by a biasing member 76, such as a spring. Specifically, the pawl 74 is biased outward against the teeth of the ratchet wheel 44, with the tip of the pawl interacting with the counterclockwise side 88 and the clockwise side 90 of the teeth of the ratchet wheel 44. In a first mode, the force attempts to rotate the sun gear 42 clockwise. However, due to the asymmetry of the teeth, the tip of the pawl 74 catches on the clockwise side 90 of the tooth, preventing the sun gear 42 from rotating in the clockwise direction. In a second mode, the force causes the sun gear 42 to rotate counterclockwise. In this case, the tip of the pawl 74 drags along the outer surface of the counterclockwise side 88 of an adjacent tooth, then along another adjacent tooth, and so on, allowing the sun gear 42 to rotate in the counterclockwise direction.

Figure 9 shows a schematic diagram of a controller 94 and related elements that control how and when the transmission changes gear ratios. The controller 94 communicates with at least one input device 92 to receive input signals, and the controller 94 also communicates with a battery 96 and the electric motor 26 to control how and when the battery 96 provides power to the electric motor 26. Communication is via a wired connection as shown in Figure 9, including a wire extending through an opening in the brake shaft (32 in Figure 2) to provide power from the battery 96 to the electric motor 26, although it will be understood that the present disclosure encompasses other forms of signal and power transmission, such as wireless communication protocols and electromagnetic induction.

The input devices 92 include sensors such as buttons, dials, and touchscreens for user input. For example, one input device 92 is a sensor that detects the angular velocity of a component, such as the carrier of the outer planetary gear set. The input device 92 sends an input signal to the controller 94. Speed data for various components can also be obtained from input devices 92 such as torque sensors, Hall sensors, and acceleration sensors. In some situations, the input device 92 sends an input signal to the controller 94 indicative of the angular velocity of the carrier and, therefore, the angular velocity of the drive sprocket. If the angular velocity is relatively slow and below a predetermined threshold, the controller 94 determines that the user requires assistance, and the controller 94 causes the battery 96 to transmit power to the electric motor 26 to change the gear ratio and increase the transmission output torque at the ring bearing and housing.

The input device 92 may include buttons, dials, a touchscreen, or the like for user input. The user may operate the input device 92 to, for example, set a pedal assist level between 1 and 10, where 1 represents low output torque and 10 represents high torque, assisting the initial propulsion of the bicycle. The input device 92 sends an input signal to the controller 94. The controller 94 may apply information about the pedal assist level in a number of ways. Based on the pedal assist level, the controller 94 may change the predetermined thresholds for the angular velocity of the carrier and drive sprocket, as described above. Thus, a pedal assist level of 10 indicates that the user desires more assistance and greater output torque, and the controller 94 may change the gear ratio of the derailleur to output higher torque at higher angular velocity thresholds of the carrier and drive sprocket compared to pedal assist level 1 (i.e., a slight decrease in angular velocity causes the derailleur to output higher torque). This means less assistance to the user, a different gear ratio, and lower output torque. In other situations, based on the pedal assist level, the controller 94 varies the amperage of power transferred from the battery 96 to the electric motor 26, rather than varying the threshold angular velocity of the carrier and drive sprocket. In some embodiments, the controller 94 varies the amperage and the threshold. Thus, based on these conditions, the controller 94 determines "when" to allow power to be transferred to the electric motor 26 and "how" to transfer it, e.g., at a constant or varying amperage.

The operation of the controller 94 and associated elements allows the controller 94 to operate in a number of different modes. In one mode, the user manually selects the speed ratio between the ring gear and the carrier. This speed ratio can be expressed as:

where ω _Ring is the angular velocity of the ring gear and ω _Carrier is the angular velocity of the carrier of the outer planetary gear set. In some embodiments, the user may select a speed ratio i between about 0.67 and 1.5. The angular velocity of the sun gear, ω _Sun , is expressed as:

Here, N _Sun is the number of teeth on the sun gear, and N _Ring is the number of teeth on the ring gear. Each tooth number is recognized by the controller 94, and the input device 92 detects the carrier angular velocity ω _Carrier . This provides the sun gear angular velocity ω _Sun and the overall speed ratio i. Therefore, the controller supplies power from the battery 96 to the electric motor 26 to generate the sun gear angular velocity ω _Sun that matches the speed ratio i set by the user.

In another mode, the user manually selects the desired pedal rotation speed, which determines the carrier angular velocity ω _Carrier . Accordingly, the controller 94 varies the sun gear speed ratio i and angular velocity ω _Sun so that the user naturally pedals at the desired rotation speed. If the input device 92 detects that the rotation speed is too slow, the controller 94 decreases the speed ratio i until the target rotation speed is achieved. Conversely, if the input device 92 detects that the rotation speed is too fast, the controller 94 increases the speed ratio i until the target rotation speed is achieved.

In yet another mode, the variables in Equation 11 are varied by the controller 94 to minimize the amount of power transferred from the battery 96 to the electric motor 26 while still providing the user with at least some gear ratio and/or speed ratio variability.

Furthermore, in some embodiments, one input device 92 is a sensor that detects the user sitting on the bicycle saddle. Based on the readings from the input device 92, the controller can cause the electric motor to change the gear ratio of the transmission or the gear ratio between the carrier and the ring.

While various aspects of the present invention have been described in detail, it will be apparent that modifications and variations of these embodiments will occur to those skilled in the art. However, it is to be understood that such modifications and variations are within the spirit and scope of the present invention, as set forth in the following claims. Furthermore, the invention described herein may be practiced in other embodiments and in various ways. It should be understood that the phraseology and terminology used herein are for the purpose of description only and should not be regarded as limiting.

Claims (20)

a carrier configured to receive an input torque;
a plurality of outer planetary gears rotatably engaged with the carrier;
a sun gear disposed within and engaging the plurality of outer planetary gears, the sun gear being selectively rotatable;
a ring gear disposed around and engaging the plurality of outer planetary gears;
In a first mode with the input torque, the sun gear is stationary, and the carrier and the plurality of outer planetary gears are configured to drive the ring gear with a first output torque;
In a second mode driven by the input torque, the sun gear rotates in the same direction as the carrier, and the carrier and the plurality of outer planetary gears are configured to drive the ring gear with a second output torque greater than the first output torque. The continuously variable transmission according to claim 1, further comprising an electric motor that engages with the sun gear to selectively rotate the sun gear. a plurality of internal planetary gears disposed within and engaging the sun gear;
3. The continuously variable transmission according to claim 2, wherein an output pinion of the electric motor is disposed within and engages the plurality of inner planetary gears to transmit motor torque from the electric motor to the sun gear and selectively rotate the sun gear. a ratchet wheel connected to the inner surface of the sun gear;
a drive shaft disposed within the ratchet wheel;
2. The continuously variable transmission of claim 1, further comprising a deflection pawl disposed on the drive shaft, the deflection pawl configured to selectively engage the ratchet wheel so that the sun gear rotates in only one direction relative to the drive shaft. The continuously variable transmission according to claim 1 , further comprising a drive sprocket that engages with the carrier via a one-way clutch, wherein the drive sprocket transmits the input torque to the carrier when rotating in only one direction relative to the carrier. 2. The continuously variable transmission according to claim 1, further comprising a housing in which the sun gear, the plurality of outer planetary gears, and the carrier are at least partially disposed, the ring gear being connected to an inner surface of the housing such that the housing receives the first output torque and the second output torque. 7. The continuously variable transmission of claim 6, wherein the housing is configured to receive at least one spoke of a wheel, such that rotation of the housing rotates the wheel. a ring gear configured to receive the output torque;
a plurality of outer planetary gears disposed within and engaging the ring gear, the plurality of outer planetary gears configured to receive a first input torque;
a sun gear disposed within and engaging the plurality of outer planetary gears;
an electric motor engaged with the sun gear and selectively rotating the sun gear with a second input torque, wherein the output torque is proportional to the first input torque and the second input torque, and the electric motor is configured to continuously change the second input torque to continuously change the gear ratio between the output torque and the first input torque. 9. The continuously variable transmission of claim 8, further comprising a carrier connected to the plurality of outer planetary gears, the carrier configured to receive the first input torque and to transmit the first input torque to the plurality of outer planetary gears. 10. The continuously variable transmission of claim 9, further comprising a shaft, wherein the sun gear engages the shaft via a one-way clutch such that the sun gear rotates in only one direction relative to the shaft. 10. The continuously variable transmission according to claim 9, further comprising a drive sprocket that engages with the carrier via a one-way clutch, the drive sprocket transmitting the first input torque to the carrier only when the drive sprocket rotates in one direction relative to the carrier. 9. The continuously variable transmission of claim 8, further comprising a controller in communication with the electric motor, the controller configured to receive an input signal, and the controller configured to cause the electric motor to rotate the sun gear based on the input signal. The continuously variable transmission of claim 12 , further comprising an input device in communication with the controller, the input device configured to transmit the input signal to the controller based on the input signal. The continuously variable transmission of claim 12 , further comprising a battery in communication with the controller, the controller configured to cause the battery to transfer power to the electric motor. a first shaft and a second shaft configured to be secured to a vehicle, the first shaft having an opening;
an electric motor fixed to the first shaft and configured to receive power through the opening in the first shaft;
a sun gear having a ring gear, a plurality of outer planetary gears disposed within and engaging the ring gear, and a sun gear disposed within and engaging the plurality of outer planetary gears, wherein the sun gear engages with the second shaft via a one-way clutch such that the sun gear rotates in only one direction relative to the second shaft, and the electric motor is configured to rotate the sun gear in one direction relative to the second shaft at a varying angular velocity and change the gear ratio between the ring gear and a carrier connected to the plurality of outer planetary gears. 16. The continuously variable transmission according to claim 15, further comprising a plurality of inner planetary gears rotatably connected to the second shaft, the plurality of inner planetary gears being disposed within the sun gear and engaging with the sun gear, and an output pinion of the electric motor being disposed within the plurality of inner planetary gears and engaging with the plurality of inner planetary gears to rotate the plurality of inner planetary gears and the sun gear. 17. The continuously variable transmission according to claim 16, wherein the output pinion is connected to an output shaft of the electric motor, and a bearing disposed within a partition wall of a housing supports the output shaft of the electric motor. 17. The continuously variable transmission of claim 16, wherein the plurality of outer planetary gears comprises four outer planetary gears and the plurality of inner planetary gears comprises three inner planetary gears. 16. The continuously variable transmission of claim 15, further comprising a housing at least partially enclosing the electric motor and the planetary gear set, wherein a first bearing is disposed between the housing and the first shaft such that the housing can rotate about the first shaft, and a second bearing is disposed between the housing and the carrier such that the housing can rotate about the carrier. 16. The continuously variable transmission of claim 15, further comprising a controller in communication with the electric motor, the controller configured to receive an input signal, the controller configured to cause the electric motor to rotate the sun gear based on the input signal.