A bicycle central motor stepless speed change power assembly

Abstract

The technology belongs to the field of middle motor stepless speed change of electrically assisted bicycle, and the features of the technology are that the power of the motor has stepless speed change assisting function and stepless speed change accelerating function, the bicycle has electronic control stepless speed change function in the speed range of the whole running process of the bicycle without mechanical speed change, and the implementation mode is that a differential mechanism composed of two-stage planetary gears is arranged at the output end, the inner ring of the two-stage planetary gear assembly is an integral structure, the inner ring is connected with the right end cover through a non-reverse one-way bearing, the central gear of the two-stage planetary gear assembly is anti-rotation connected, the input side planetary carrier is fixedly connected with the crankshaft, the output side planetary carrier is anti-rotation connected with the output sleeve, the rotor of the motor is connected with the crankshaft through a one-way bearing after being decelerated and is connected with the inner ring of the differential mechanism through a one-way bearing, and the motor can rotate in positive and reverse directions.

Description

Technical Field

[0001] A continuously variable transmission (CVT) powertrain for a mid-mounted motor in a bicycle belongs to the field of mid-mounted motors in electric-assist bicycles, and further to the field of continuously variable transmissions for mid-mounted motors in electric-assist bicycles. Background Technology

[0002] The mid-mounted motor assist system of electric-assist bicycles is a relatively mature technology, but the gear shifting system still requires mechanical gear shifting. Hybrid technology in automobiles uses an electronic control system to coordinate the work of two motors and the engine, which can achieve continuously variable transmission (CVT). There are currently no mature examples of electric-assist bicycles that use a single mid-mounted motor and achieve CVT without mechanical gear shifting. Summary of the Invention

[0003] A continuously variable transmission (CVT) powertrain for a bicycle with a mid-mounted motor is characterized by having both continuously variable power assist and continuously variable acceleration functions. Furthermore, it provides electronically controlled continuously variable transmission throughout the entire speed range of the bicycle's journey, without requiring mechanical gear shifting.

[0004] The described bicycle mid-mounted motor continuously variable transmission powertrain has a differential mechanism consisting of a two-stage planetary gear assembly at the output end. The internal gear rings of the two-stage planetary gear assemblies are an integral structure, and the right end of the internal gear ring is connected to the right end cover through a one-way anti-reverse bearing, preventing the internal gear ring from rotating in the forward direction but allowing it to rotate in the reverse direction. The central gear of the two-stage planetary gear assembly is anti-rotationally connected. The planetary carrier on the input side is fixedly connected to the crankshaft and is the power input end. The planetary carrier on the output side is anti-rotationally connected to the output sleeve and is the power output end. The driving torque of the bicycle is input from the planetary carrier on the input side of the differential mechanism and output from the planetary carrier on the output side of the differential mechanism, transmitting the driving torque for forward rotation.

[0005] The aforementioned bicycle mid-mounted motor continuously variable transmission powertrain has a continuously variable transmission function. The torque of the motor's forward rotation is reduced by a two-stage reduction planetary gear assembly, and then output by the planetary carrier of the output stage, which is connected to the crankshaft through an inner one-way bearing to output a forward rotation assist torque.

[0006] The aforementioned bicycle mid-mounted motor continuously variable transmission (CVT) powertrain allows the motor to rotate in reverse. The torque generated by the motor's reverse rotation is reduced by a two-stage planetary gear assembly and then transmitted from the output stage planetary carrier through an external one-way bearing, connecting spokes, and finally to the internal gear ring of the differential mechanism assembly. This causes the internal gear ring of the differential mechanism assembly to rotate in reverse, thereby accelerating the forward rotation of the output-side planetary carrier of the differential mechanism assembly, thus achieving the acceleration function of the continuously variable transmission.

[0007] The described bicycle mid-drive motor continuously variable transmission (CVT) powertrain has a cylindrical structure centered on the crankshaft, with the input end on the left and the output end on the right. The CVT powertrain integrates a controller, encoder, motor assembly, reduction gear assembly, differential gear assembly, and torque sensor assembly. Externally, it includes a power battery assembly, display screen assembly, and power steering throttle assembly. The display screen assembly and power steering throttle assembly are wirelessly connected to the controller via Bluetooth. The crankshaft is a hollow structure, and the torque sensor assembly is installed inside the crankshaft's inner bore.

[0008] The aforementioned bicycle mid-mounted motor continuously variable transmission powertrain includes a housing assembly, a motor assembly, a reduction mechanism assembly, a differential mechanism assembly, a crankshaft assembly, a torque sensor assembly, and a controller assembly.

[0009] The aforementioned bicycle mid-mounted motor continuously variable transmission (CVT) powertrain is characterized by: a housing assembly including a left end cover, a left end cap, a housing, a right end cap, an output sleeve assembly, housing bolts, and cover bolts; a barrel-shaped structure extending from the left end of the left end cap and connected to the left end cover via cover bolts; an assembly with an internal cavity for mounting a controller assembly; wiring holes and heat dissipation fins on the outer periphery of the extended portion of the left end cap; the wiring holes for wiring the controller to the power battery assembly; an encoder mounted on the right end face of the left end cap; and a... There are two sets of wiring holes, one for wiring the controller to the motor and the other for wiring the encoder to the controller. The left end cover has a hole in the center and a sealing ring installed for the crankshaft to pass through. The left end cover also has a hole in the center and a bearing and a sealing ring installed for the crankshaft installation. The outer shell is a cylindrical structure and is connected to the left and right end covers by outer shell bolts to form an integral whole with an internal cylindrical cavity. The outer shell is fixedly connected to the bicycle frame. The right end cover has a hole in the center and a sleeve-shaped protrusion on its left end. A one-way anti-reverse bearing is installed on the outer circumference of the protrusion, and a bearing and a sealing ring are installed on the inner circumference of the protrusion for the installation of the output sleeve assembly. The output sleeve assembly has a hole in the center and is equipped with a bearing and a sealing ring for the installation of the crankshaft. The left end of the output sleeve is anti-rotationally connected to the output side planetary carrier of the differential mechanism assembly, and the right end of the output sleeve is fixedly connected to the chainring pulley.

[0010] The aforementioned bicycle mid-mounted motor continuously variable transmission powertrain is characterized by the following: the motor assembly includes a motor stator, a motor rotor, an output flange, and a rotor bearing; the outer circumference of the motor stator and the inner gear ring of the planetary gear reduction assembly are press-fitted as a whole and jointly press-fitted and fixed to the right side of the left end cover; the motor wires are connected to the controller through the end holes of the left end cover; the inner circumference of the motor rotor and the output flange are press-fitted as a whole and supported on the crankshaft by the rotor bearing on the inner circumference of the output flange; an encoder disk is installed on the left side of the output flange; the motor rotor can achieve forward and reverse rotation under the control of the controller; and the motor assembly is installed in the internal cylindrical cavity of the outer shell assembly.

[0011] The aforementioned continuously variable transmission (CVT) powertrain for a mid-mounted motor in a bicycle is characterized by: a reduction mechanism assembly including a two-stage planetary gear reduction system, wherein the internal gear rings of the two-stage planetary gear reduction system are an integral structure. Both stages of the planetary gear reducer assembly have a center gear input and a planetary carrier output. The two stages are fitted around the crankshaft and installed within the internal cylindrical cavity of the housing assembly. The center gear of the input stage planetary gear reducer assembly is fixedly connected to the output flange of the motor rotor. The planetary carrier of the output stage planetary gear reducer assembly is the output end of the motor power after reduction. A sleeve-like structure extends from the right end of the planetary carrier. An inner one-way bearing is installed on the inner circumference of this sleeve, and an outer one-way bearing is installed on the outer circumference. The inner one-way bearing is fitted onto the crankshaft, allowing the forward torque of the motor rotor to drive the crankshaft to rotate forward. This also ensures that when the motor has no power output, the pedaling force has no motor resistance, and the motor rotor can rotate in the opposite direction relative to the crankshaft. The outer one-way bearing is connected to the internal gear ring of the differential mechanism via spokes, so that when the motor rotates in the opposite direction, the internal gear ring also rotates in the opposite direction. The torque of this reverse rotation and the pedaling torque enter the differential mechanism assembly together, coupling torque and speed.

[0012] The described bicycle mid-mounted motor continuously variable transmission (CVT) powertrain is characterized by: a differential mechanism assembly comprising an input-side planetary gear assembly and an output-side planetary gear assembly; the internal gear rings of the two-stage planetary gear assemblies are an integral structure; the central gears of the two-stage planetary gear assemblies are anti-rotationally connected; the right end of the internal gear ring is connected to the right end cover via a backstop connecting plate and a backstop one-way bearing, preventing the internal gear ring from rotating forward but allowing it to rotate in reverse; the left end of the internal gear ring is connected to the planet carrier of the output-stage planetary gear reduction assembly via a connecting spoke and an outer one-way bearing; the input-side planet carrier is fixedly connected to the crankshaft and serves as the power input end; the output-side planet carrier is anti-rotationally connected to the output sleeve and serves as the power output end; when there is no motor power, the torque exerted by the pedaling motion drives the input-side planet carrier to rotate forward via the crankshaft, and drives the output-side planet carrier to output a forward rotation torque via the central gear; when the motor rotates forward, the electric... The torque of the motor and the torque of the pedaling person are superimposed on the crankshaft and enter the input planetary carrier of the differential mechanism. Through the central gear, it drives the output planetary carrier, outputting a superimposed torque for forward rotation. Through the controller, the forward speed of the motor is continuously changed, realizing the stepless speed-assist function. When the motor rotates in the reverse direction, the internal gear ring of the differential mechanism rotates in the reverse direction. Its reverse rotation torque and the pedaling torque enter the differential mechanism together, coupling torque and speed. The reverse torque of the motor and the forward torque of the pedaling person form a pair of action and reaction forces on the input planetary carrier. The reverse speed of the motor and the forward speed of the pedaling person are positively superimposed on the central gear and in the output planetary carrier, resulting in a positive and negative superposition. As a result, the output planetary carrier rotates forward with acceleration. Through the controller, the reverse speed of the motor is continuously changed, realizing the stepless acceleration function of the output planetary carrier.

[0013] The aforementioned bicycle mid-drive motor continuously variable transmission (CVT) powertrain is characterized by: a hollow crankshaft with a torque sensor assembly installed in its inner bore; the crankshaft is positioned at the center of the bicycle mid-drive motor CVT powertrain; its left end is supported by a bearing inside the left end cover to the outer housing assembly; and its right end is supported by a bearing on the inner circumference of the output sleeve and a bearing inside the right end cover to the outer housing assembly. The torque sensor assembly includes a sensor cylinder, a sensor stress plate, a fixing gear sleeve, a button battery, a battery holder, a circuit board, and a sealing cover. The sensor stress plate is pasted around the perimeter, and the wiring is introduced into the inner hole. The outer periphery and end face of the fixing toothed sleeve are toothed. The sensor cylinder is press-fitted into the middle section of the crankshaft inner hole through the fixing toothed sleeves at the left and right ends. The left end of the crankshaft inner hole is equipped with a circuit board and a sealing cover, and the right end of the crankshaft inner hole is equipped with a button battery and a sealing cover. The power wire of the button battery passes through the inner hole of the sensor cylinder and connects to the circuit board. The circuit board has signal processing, signal amplification and Bluetooth signal transmission functions, and transmits the torque sensor signal to the controller in real time.

[0014] The aforementioned bicycle mid-drive motor continuously variable transmission (CVT) powertrain is characterized by: a controller assembly including a power battery wiring port, a motor wiring port, an encoder wiring port, a power module, a Bluetooth communication module, a motor drive module, a safety control module, and a computing module. The control strategy of the bicycle mid-drive motor CVT powertrain is as follows: Three values ​​are set as reference intermediate values ​​for the bicycle's pedaling frequency, pedaling torque, and bicycle speed during flat-road cruising. When the pedaling frequency decreases, the pedaling torque increases, and the bicycle speed decreases to a set threshold value for each of the three values, the controller determines that the bicycle has entered an uphill section and controls the motor to enter assist mode. When the pedaling frequency increases, the pedaling torque decreases, and the bicycle speed increases to a set threshold value for each of the three values, the controller determines that the bicycle has entered a flat-road acceleration or downhill section and controls the motor to enter acceleration mode. In the motor assist mode, the pedaling torque and the motor's forward torque are... The crankshaft generates superimposed torque to provide assistance. In the motor acceleration mode, the torque of the pedaling motion and the reverse rotation torque of the motor are coupled in the differential mechanism assembly, causing the planetary carrier on the output side to accelerate forward, achieving stepless acceleration. At the same time, the pedaling torque and the reverse rotation torque of the motor generate opposing torques in the differential mechanism, forming a pair of action and reaction forces. The key technology of the controller lies in the fact that when the motor rotates in reverse and enters the acceleration mode, the computing module calculates the value of the pedaling torque, the pedaling frequency, and the bicycle speed based on the signal from the torque sensor. It also calculates the mechanical characteristic curve value of the pedaling output based on the changes in the value of the pedaling torque, the pedaling frequency, and the bicycle speed, and controls the motor to output power according to the corresponding characteristic curve. This ensures that the pedaling torque and the motor torque maintain a dynamic balance, achieving a smooth, seamless, and stepless continuously variable transmission. Attached Figure Description

[0015] Figure 1 This is an isometric drawing of the overall assembly of a bicycle's mid-mounted motor continuously variable transmission (CVT) powertrain.

[0016] Figure 2 This is a cross-sectional view of the overall assembly of a bicycle's mid-mounted motor continuously variable transmission (CVT) powertrain.

[0017] Figure 3 This is a cross-sectional view of the housing assembly of a bicycle's mid-mounted motor continuously variable transmission (CVT) powertrain.

[0018] Figure 4 This is an isometric drawing of the motor assembly of a mid-mounted continuously variable transmission (CVT) powertrain for bicycles.

[0019] Figure 5 This is a cross-sectional view of the reduction assembly of a bicycle's mid-mounted motor continuously variable transmission (CVT) powertrain.

[0020] Figure 6This is a cross-sectional view of the differential assembly of a bicycle's mid-mounted motor continuously variable transmission (CVT) powertrain.

[0021] Figure 7 This is a cross-sectional view of the crankshaft assembly of a mid-mounted motor continuously variable transmission (CVT) powertrain for bicycles.

[0022] Figure 2 In the diagram, number 1 is the outer casing assembly, number 2 is the motor assembly, number 3 is the reduction mechanism assembly, number 4 is the differential mechanism assembly, number 5 is the controller assembly, number 6 is the crankshaft assembly, number 7 is the output sleeve assembly, number 8 is the torque sensor assembly, and number 9 is the encoder.

[0023] Figure 3 In the diagram, number 1 is the outer casing, number 2 is the left end cover, number 3 is the right end cover, number 4 is the output sleeve, number 5 is the bearing, number 6 is the sealing ring, number 7 is the left protective cover, number 8 is the sealing ring, number 9 is the bearing, number 10 is the bearing, number 11 is the sealing ring, and number 12 is the bearing.

[0024] Figure 4 In the diagram, number 1 is the motor stator, number 2 is the motor rotor, number 3 is the rotor output flange, number 4 is the rotor bearing, and number 5 is the encoder disk.

[0025] Figure 5 In the diagram, number 1 is the internal gear ring of the reduction mechanism, number 2 is the input stage planetary carrier of the reduction mechanism, number 3 is the input stage planetary gear of the reduction mechanism, number 4 is the output stage planetary gear of the reduction mechanism, number 5 is the input stage center gear of the reduction mechanism, number 6 is the output stage center gear of the reduction mechanism, number 7 is the output stage planetary carrier of the reduction mechanism, and number 8 is the internal one-way bearing.

[0026] Figure 6 In the diagram, number 1 is the internal gear ring of the differential mechanism, number 2 is the input planetary gear of the differential mechanism, number 3 is the output planetary gear of the differential mechanism, number 4 is the output planetary carrier of the differential mechanism, number 5 is the input planetary carrier of the differential mechanism, number 6 is the check plate, number 7 is the check bearing, number 8 is the output center gear of the differential mechanism, number 9 is the connecting spoke, number 10 is the external bearing, and number 11 is the input center gear of the differential mechanism.

[0027] Figure 7 In the diagram, number 1 is the crankshaft, number 2 is the torque sensor cylinder, number 3 is the fixing gear sleeve, number 4 is the button battery, number 5 is the crankshaft sealing cover, number 6 is the battery connection wire, number 7 is the fixing gear sleeve, number 8 is the circuit board, and number 9 is the crankshaft sealing cover. Detailed Implementation

[0028] This technical solution has three implementation methods.

[0029] The first implementation method is the bicycle mid-mounted motor continuously variable transmission powertrain described above. Its advantage is that it only requires one mid-mounted motor to achieve both motor assist and continuously variable acceleration functions, and the motor power is required to be 250 watts. Its disadvantage is that the motor power requirement during the bicycle acceleration phase is actually 100 watts, so there is power waste for a 250-watt motor. In addition, during the motor assist phase, with the rider's pedaling frequency remaining unchanged, the bicycle speed does not decrease, the rider's pedaling torque does not increase, but the motor's energy consumption increases.

[0030] The second implementation is a dual-motor mode. The mechanical structure remains unchanged, consisting of a mid-drive bicycle motor and a hub motor. The mid-drive motor has a power of 100 watts, and the hub motor has a power of 150 watts. The operating mode of the mid-drive motor is the same as that of the first implementation, except that during the motor assist phase, the 100-watt mid-drive motor first engages the assist mode. When the 100-watt power is insufficient, the 150-watt hub motor then engages the assist mode. The hub motor can recover braking energy and assist braking when the bicycle is braking or going downhill. The advantage of the second implementation is that the power utilization of the motors is more rational and energy-efficient. The disadvantage is that the dual motors increase the cost and the overall weight of the bicycle, and do not solve the problem of slowing down when the bicycle is going uphill or when the motor assists.

[0031] The third implementation is a dual-motor mode. In the above mechanical structure, the inner one-way bearing, outer one-way bearing, and anti-reverse one-way bearing are eliminated. An electronically controlled locking mechanism is installed at the position of the anti-reverse one-way bearing. The planetary carrier at the output end of the reduction mechanism is connected to the internal gear ring of the differential mechanism to resist rotation. A 100-watt mid-mounted motor and a 250-watt hub motor are added. The mid-mounted motor is only responsible for speed regulation and does not provide power assist. Reverse rotation of the mid-mounted motor is the acceleration state, and forward rotation is the deceleration state. In the deceleration state, the mid-mounted motor operates in generator mode, which can recover some of the energy from pedaling. The hub motor is a power assist motor and switches to generator mode when the bicycle brakes or goes downhill, recovering the energy from braking and downhill driving. The advantage of the third implementation is that it solves all the disadvantages of the above two implementations and perfectly realizes the continuously variable transmission function of the electric-assist bicycle. The disadvantages are that the cost of the motor and controller increases significantly, and the weight of the bicycle increases.

Claims

1. A continuously variable transmission (CVT) powertrain for a bicycle with a mid-mounted motor, characterized in that: The bicycle's mid-mounted motor continuously variable transmission powertrain has continuously variable power assist and continuously variable acceleration functions. When mechanical gear shifting is not required, the bicycle has electronically controlled continuously variable transmission function throughout the entire speed range of its journey. The aforementioned bicycle mid-mounted motor continuously variable transmission powertrain has a differential mechanism consisting of a two-stage planetary gear assembly at the output end. The internal gear rings of the two-stage planetary gear assemblies are an integral structure, and the right end of the internal gear ring is connected to the right end cover through a one-way anti-reverse bearing, which restricts the forward rotation of the internal gear ring and makes it only rotate in the reverse direction. The central gear of the two-stage planetary gear assembly is anti-rotationally connected. The planetary carrier on the input side is fixedly connected to the crankshaft and is the power input end. The planetary carrier on the output side is anti-rotationally connected to the output sleeve and is the power output end. The driving torque of the bicycle is input from the planetary carrier on the input side of the differential mechanism and output from the planetary carrier on the output side of the differential mechanism, transmitting the driving torque of forward rotation. The aforementioned bicycle mid-mounted motor continuously variable transmission powertrain has a continuously variable transmission function. The torque of the motor's forward rotation is reduced by a two-stage reduction planetary gear assembly, and then output by the planetary carrier of the output stage, which is connected to the crankshaft through an inner one-way bearing to output a forward rotation assist torque. The aforementioned bicycle mid-mounted motor continuously variable transmission powertrain has a motor with a reverse rotation function. The reverse rotation torque of the motor is reduced by a two-stage planetary gear assembly and then transmitted from its output stage planetary carrier through an external one-way bearing, connecting spokes, and to the internal gear ring of the differential mechanism assembly. This causes the internal gear ring of the differential mechanism assembly to rotate in the reverse direction, thereby accelerating the forward rotation of the output side planetary carrier of the differential mechanism assembly, thus achieving the acceleration function of continuously variable transmission. The described bicycle mid-drive motor continuously variable transmission powertrain has a cylindrical structure centered on the crankshaft, with the input end on the left and the output end on the right. The bicycle mid-drive motor continuously variable transmission powertrain integrates a controller, encoder, motor assembly, reduction mechanism assembly, differential mechanism assembly, and torque sensor assembly. It also has an external power battery assembly, display assembly, and power assist throttle assembly. The display assembly and power assist throttle assembly are wirelessly connected to the controller via Bluetooth. The crankshaft is a hollow structure, and the torque sensor assembly is installed in the inner hole of the crankshaft. The aforementioned bicycle mid-mounted motor continuously variable transmission powertrain includes a housing assembly, a motor assembly, a reduction mechanism assembly, a differential mechanism assembly, a crankshaft assembly, a torque sensor assembly, and a controller assembly.

2. The continuously variable transmission (CVT) powertrain for a bicycle with a mid-mounted motor as described in claim 1, characterized in that: the outer casing assembly includes a left end cover, a left end cap, an outer casing, a right end cap, an output sleeve assembly, an outer casing bolt, and a cover bolt; a barrel-shaped structure extends from the left end of the left end cap and is connected to the left end cover via the cover bolt; the assembly has an internal cavity for installing a controller assembly; the outer periphery of the extended portion of the left end cap is provided with a wiring hole and heat dissipation fins; the wiring hole is used for wiring between the controller and the power battery assembly; an encoder is installed on the right end face of the left end cap; the left end cap... The end face has two sets of wiring holes, one for wiring the controller to the motor and the other for wiring the encoder to the controller. The left end cover has a hole in the center and a sealing ring installed for the crankshaft to pass through. The left end cover also has a hole in the center and a bearing and a sealing ring installed for the crankshaft installation. The outer shell is a cylindrical structure and is connected to the left and right end covers by outer shell bolts to form an integral whole with an internal cylindrical cavity. The outer shell is fixedly connected to the bicycle frame. The right end cover has a hole in the center and a sleeve-shaped protrusion on its left end. A one-way anti-reverse bearing is installed on the outer circumference of the protrusion, and a bearing and a sealing ring are installed on the inner circumference of the protrusion for the installation of the output sleeve assembly. The output sleeve assembly has a hole in the center and is equipped with a bearing and a sealing ring for the installation of the crankshaft. The left end of the output sleeve is connected to the output side planetary carrier of the differential mechanism assembly for anti-rotation. The right end of the output sleeve is fixedly connected to the chainring pulley.

3. The continuously variable transmission (CVT) powertrain for a bicycle with a mid-mounted motor as described in claim 1, characterized in that: The motor assembly includes a motor stator, a motor rotor, an output flange, and a rotor bearing. The outer circumference of the motor stator and the inner gear ring of the planetary gear reduction assembly are press-fitted into a single unit and fixed together on the right side of the left end cover. The motor wires are connected to the controller through the end holes of the left end cover. The inner circumference of the motor rotor and the output flange are press-fitted into a single unit and supported on the crankshaft by the rotor bearing on the inner circumference of the output flange. An encoder disk is installed on the left side of the output flange. The motor rotor has the function of forward and reverse rotation. The motor assembly is installed in the internal cylindrical cavity of the outer casing assembly.

4. The continuously variable transmission (CVT) powertrain for a bicycle with a mid-mounted motor as described in claim 1, characterized in that: The reduction gear assembly includes a two-stage planetary gear reduction system. The internal gear rings of both stages are integral. Both stages have a central gear input and a planetary carrier output. The two stages are fitted around the crankshaft and installed within the internal cylindrical cavity of the housing assembly. The central gear of the input stage planetary gear reduction system is fixedly connected to the output flange of the motor rotor. The planetary carrier of the output stage planetary gear reduction system is the output end of the motor power after reduction. A sleeve-like structure extends from the right end of the planetary carrier. An inner one-way bearing is installed on the inner circumference of this sleeve, and an outer one-way bearing is installed on the outer circumference. The inner one-way bearing is fitted onto the crankshaft, allowing the positive torque of the motor rotor to drive the crankshaft to rotate in the positive direction. This ensures that when the motor is not outputting power, the pedaling force has no motor resistance. Its outer one-way bearing is connected to the internal gear ring of the differential mechanism through the spokes, so that when the motor rotates in the opposite direction, its internal gear ring also rotates in the opposite direction. The torque of its reverse rotation and the torque of the person stepping on it enter the differential mechanism assembly together and couple the torque and speed.

5. The continuously variable transmission (CVT) powertrain for a bicycle with a mid-mounted motor as described in claim 1, characterized in that: The differential mechanism assembly includes an input-side planetary gear assembly and an output-side planetary gear assembly. The internal gear rings of the two-stage planetary gear assemblies are an integral structure. The central gears of the two-stage planetary gear assemblies are anti-rotationally connected. The right end of the internal gear ring is connected to the right end cover through a non-reverse connecting plate and a non-reverse one-way bearing, so that the internal gear ring cannot rotate in the forward direction, but can only rotate in the reverse direction. The left end of the internal gear ring is connected to the planet carrier of the output-stage planetary gear reduction assembly through a connecting spoke plate and an outer one-way bearing. The planet carrier on the input side is fixedly connected to the crankshaft and is the power input end. The planet carrier on the output side is anti-rotationally connected to the output sleeve and is the power output end. When there is no motor power, the torque of the pedaling force is transmitted through the crankshaft, which drives the planetary carrier on the input side to rotate in the forward direction, and through the central gear, drives the planetary carrier on the output side to output the torque of rotation in the forward direction. When the motor rotates in the forward direction, the torque of the motor and the torque of the pedal are superimposed on the crankshaft and enter the planetary carrier on the input side of the differential mechanism. Through the central gear, the planetary carrier on the output side is driven to output the superimposed torque for forward rotation. Through the controller, the forward speed of the motor is changed steplessly, realizing the stepless speed assistance function. When the motor rotates in the reverse direction, it causes the internal gear ring of the differential mechanism to rotate in the reverse direction. Its reverse rotational torque and the pedaling torque enter the differential mechanism together, coupling torque and speed. The reverse torque of the motor and the forward torque of the pedaling force form a pair of action and reaction forces on the input-side planetary carrier. The reverse speed of the motor and the forward speed of the pedaling force are positively superimposed on the central gear, and positive and negative superposition is formed on the output-side planetary carrier. As a result, the output-side planetary carrier rotates forward with acceleration. Through the controller, the reverse speed of the motor can be changed steplessly, realizing the stepless acceleration function of the output-side planetary carrier.

6. The continuously variable transmission (CVT) powertrain for a bicycle with a mid-mounted motor as described in claim 1, characterized in that: The crankshaft is a hollow structure with a torque sensor assembly installed inside its inner bore. The crankshaft is mounted at the center of the continuously variable transmission (CVT) powertrain of the bicycle's mid-drive motor. Its left end is supported by a bearing inside the left end cap, and its right end is supported by a bearing on the inner circumference of the output sleeve and a bearing inside the right end cap. The torque sensor assembly includes a sensor cylinder, a sensor stress plate, a fixing sleeve, a button battery, a battery holder, a circuit board, and a sealing cap. The sensor stress plate is attached to the outer circumference of the sensor cylinder, and wiring is introduced into the inner bore. The fixing sleeve has teeth on its outer circumference and end face. The sensor cylinder is press-fitted into the middle section of the crankshaft's inner bore via the fixing sleeves on the left and right ends. The circuit board and sealing cap are installed at the left end of the crankshaft's inner bore, and the button battery and sealing cap are installed at the right end. The button battery's power cable passes through the inner bore of the sensor cylinder and connects to the circuit board. The circuit board has signal processing, signal amplification, and Bluetooth signal transmission functions, and transmits the torque sensor signal to the controller in real time.

7. The continuously variable transmission (CVT) powertrain for a bicycle with a mid-mounted motor as described in claim 1, characterized in that: The controller components include a power battery wiring connector, a motor wiring connector, an encoder wiring connector, a power module, a Bluetooth communication module, a motor drive module, a safety control module, and a computing module. The control strategy of a mid-mounted motor continuously variable transmission (CVT) powertrain for bicycles involves setting three reference midpoints for pedaling frequency, pedaling torque, and bicycle speed during flat-road cruising. When the pedaling frequency decreases, the pedaling torque increases, and the bicycle speed decreases to a set threshold for these three values, the controller determines that the bicycle has entered an uphill section and controls the motor to enter assist mode. Conversely, when the pedaling frequency increases, the pedaling torque decreases, and the bicycle speed increases to a set threshold for these three values, the controller determines that the bicycle has entered a flat-road acceleration or downhill section and controls the motor to enter acceleration mode. In assist mode, the pedaling torque and the motor's forward rotation torque create a superposition of torques on the crankshaft, providing assistance. In acceleration mode, the pedaling torque and the motor's reverse rotation torque create a differential torque. In the actuator assembly, torque and speed are coupled, causing the planetary carrier on the output side to accelerate forward rotation, achieving stepless acceleration. At the same time, the pedaling torque and the reverse rotation torque of the motor generate torque resistance in the differential mechanism, forming a pair of action and reaction forces. The key function of the controller is that when the motor rotates in reverse and enters the acceleration mode, the computing module calculates the pedaling torque, pedaling frequency, and bicycle speed based on the signal from the torque sensor. It also calculates the mechanical characteristic curve of the pedaling output based on the changes in the pedaling torque, pedaling frequency, and bicycle speed, and controls the motor to output power according to the corresponding characteristic curve. This ensures that the pedaling torque and the motor torque are kept in dynamic balance, achieving a smooth, seamless, and stepless speed change function.

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