Power module of electric assisted bicycle

Abstract

A power module (1, 1a, 1b) of an electric assisted bicycle, comprising a pedal shaft (10), a housing (20), a motor (30), a speed reducer (40), a toothed disc output shaft (50), a pedal shaft first bidirectional bearing (81), and an encoder assembly (70). A spacing portion (24) of the housing (20) divides an internal space into a motor accommodating portion (201) and a speed reductor accommodating portion (202) in an axial direction. The pedal shaft (10) is accommodated in the housing (20) and passes through an end cover of the housing (20) in the axial direction. An extension portion (414) of a speed reductor input shaft (41) extends towards the end cover in the axial direction, and is connected to a supporting portion (210) of the end cover by means of an input shaft rear bearing (33), so as to stabilize a rotation axis. The supporting portion (210), the input shaft rear bearing (33), and the extension portion (414) are sequentially sleeved from inside to outside in a radial direction, thereby facilitating axial configuration of the encoder assembly (70), and increasing the use space.

Description

Power module for electric power-assisted bicycles Technical Field

[0001] This case involves a power module, particularly a power module for a mid-mounted electric power-assisted bicycle. Background Art

[0002] An electric assisted bicycle (E-Bike), also known as an e-Bike, is a bicycle with an integrated motor and reducer to provide motor-assisted propulsion. There are many types of electric bicycles on the market, but they are generally divided into two categories: electric assisted bicycles that detect and assist the rider's pedaling force, and general electric bicycles that only use motors to drive the wheel hub. Since electric assisted bicycles must integrate both human and motor-assisted forces, reducing the size and space has always been an important issue in the design of the power module. In addition, the power module must also meet the needs of dual power (human and motor-assisted force) at the same time to optimize the power module's performance in different usage scenarios. Therefore, the design of the power module of an electric assisted bicycle is quite difficult.

[0003] The power module of an electric-assisted bicycle primarily consists of a motor and a reducer, housed within the module's housing. Existing power modules radially connect the motor and reducer from the central pedal axis. The reducer's fixed teeth connect to the housing, making installation difficult and increasing the module's radial thickness.

[0004] Furthermore, due to space constraints, existing power modules also include a torque sensor connected between the module housing's inner diameter and the pedal shaft's bidirectional bearings, transmitting pedal force through the pedal shaft bearings. Because the torque sensor isn't connected in series with the force transmission path, torque sensing requires calculating pedal torque from pedal force, rather than sensing actual pedal torque. This results in significant sensing errors, and due to its placement, it can only measure unilateral pedal force.

[0005] In view of this, it is necessary to provide a power module for a mid-mounted electric power-assisted bicycle with an axially arranged motor and reducer, which can optimize the radial space, meet the requirements of miniaturization and realize optimized measurement of pedaling torque, so as to solve the shortcomings of the existing technology.

[0006] Summary of the Invention

[0007] The purpose of this application is to provide a power module for a mid-mounted electric-assisted bicycle with an axially arranged motor and reducer. This module optimizes radial space while meeting the requirements for miniaturization and enabling optimized pedal torque measurement. Furthermore, the encoder assembly can be configured axially to save radial space.

[0008] Another object of this invention is to provide a power module for an electric power-assisted bicycle. A spacer extending radially inward from the housing middle frame divides the interior space of the housing into an axially arranged motor housing and a reducer housing. When the motor and reducer are axially sleeved onto the pedal shaft, the motor stator and the reducer's fixed teeth can be fixedly connected to opposite sides of the spacer, respectively, achieving aligned installation, improving assembly efficiency, enhancing stator heat dissipation, and strengthening the structure. Furthermore, when the axially arranged motor and reducer are connected via a reducer input shaft, the motor power can be transmitted to the reducer. One end of the reducer input shaft forms an input shaft rotor portion connected to the motor rotor (output shaft) or the motor output shaft, and the other end forms an input shaft eccentric portion connected to the movable teeth of the reducer. The input shaft body between the input shaft rotor portion and the input shaft eccentric portion can be radially connected to a third side of the spacer via a bearing, so that the reducer input bearing abuts the spacer. Furthermore, the reducer input shaft extends axially and bears against the support portion of the end cap. Thus, when the motor drives the reducer, the rotation axis of the reducer input shaft can operate stably. In other words, the stator of the motor is axially attached to one side of the spacer, which can increase the contact area between the stator and the housing and improve the heat dissipation efficiency. The fixed teeth of the reducer are axially attached to the other side of the spacer, which not only facilitates positioning and installation and strengthens the structure, but also can further reduce the radial space of the power module. In addition, the support part of the end cover, the rear bearing of the input shaft, and the reducer shaft-in-shaft extension are arranged in sequence from the inside to the outside in the radial direction. The outer diameter of the support part is smaller than the inner diameter of the extension part, which helps to increase the usable space between the left end cover and the motor, facilitates the installation of the driver and the axial configuration of the encoder assembly, and is more conducive to the optimization of the radial space, so that the power module of the electric power-assisted bicycle further meets the needs of miniaturization.

[0009] Another object of this invention is to provide a power module for an electric power-assisted bicycle. The motor and reducer are axially arranged on opposite sides of a housing partition. Compared to a radially stacked design, this design only slightly increases the axial volume. This additional size increase can be absorbed by modifying the bicycle frame design, further reducing the overall volume of the power module and making it suitable for mounting on a bicycle frame. The configuration of the reducer's fixed gears, motor stator, and reducer input shaft body connected to three sides of the housing partition optimizes the space utilization of the entire power module. This allows for the torque sensor to be connected to the pedal shaft for accurate dual pedal force sensing, while also meeting the aforementioned requirements of structural strength, stable reducer input shaft rotation axis, and effective stator heat dissipation. Furthermore, the input shaft rear bearing (motor rotating bearing) is connected between the support portion of the left end cap and the extension of the reducer input shaft (motor rotating shaft). Wave springs are used to eliminate gaps, increasing the usable space for the driver panel and further enabling the encoder assembly to save radial space through axial configuration.

[0010] To achieve the aforementioned objectives, this invention provides a power module for an electric power-assisted bicycle, comprising a housing, a pedal shaft, a motor, a reducer, a first bidirectional bearing for the pedal shaft, and an encoder assembly. The housing defines radial and axial directions and comprises end caps, a middle frame, and a spacer. The end caps are connected to the middle frame to define an interior space. The spacer extends radially from the middle frame into the interior space and axially divides the interior space into a motor accommodating portion and a reducer accommodating portion. The motor accommodating portion is located between the end cap and the spacer. The pedal shaft is housed in the housing and extends axially through the end cap. The motor is housed in the motor accommodating portion and is axially fixed to the spacer. The reducer is housed in the reducer housing and axially fixed to the spacer. The reducer input shaft comprises an input shaft body, an input shaft rotor, and an extension. The input shaft rotor is located between the input shaft body and the extension and radially connected to the motor output shaft of the motor. The input shaft body is radially connected to the spacer. The extension extends axially toward the end cap and is connected to the support portion of the end cap via an input shaft rear bearing. The support portion, input shaft rear bearing, and extension are sequentially sleeved radially from the interior toward the center frame. A first bidirectional bearing for the pedal shaft is radially sleeved between the pedal shaft and the support portion. An encoder assembly is axially disposed between the extension portion and the end cap. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG1 is a cross-sectional view of a power module of an electric power-assisted bicycle according to a first preferred embodiment of the present invention;

[0012] FIG2 is a schematic diagram illustrating a torque flow path of the power module of the first preferred embodiment of the present invention when a right pedaling torque is input;

[0013] FIG3 is a schematic diagram illustrating a torque flow path of the power module of the first preferred embodiment of the present invention when a left pedaling torque is input;

[0014] FIG4 is a cross-sectional view of a power module of an electric power-assisted bicycle according to a second preferred embodiment of the present invention;

[0015] FIG5 is a cross-sectional view showing a power module of an electric power-assisted bicycle according to a third preferred embodiment of the present invention.

[0016] DESCRIPTION OF REFERENCE NUMERALS 1, 1a, 1b: Power module 10: Pedal shaft 20: Housing 201: Motor accommodating portion 202: Reducer accommodating portion 21: Left end cover 210: Support portion 22: Middle frame 23: Right end cover 24: Spacer 30: Motor 300: Motor output shaft 31: Stator 32: Magnet 33: Input shaft rear bearing 40: Reducer 41: Reducer input shaft 411: Input shaft body 412: Input shaft rotor 413: Input shaft eccentric portion 414: Extension portion 42: Movable tooth 43: Fixed tooth 44: Reducer output shaft 50: Sprocket output shaft 51: Chain sprocket 60: Sensor assembly 70: Encoder assembly 71: Rotating portion 72: Sensing portion 73: Driver 81: First bidirectional bearing of the pedal shaft 82: First bidirectional bearing of the input shaft body 83: Second bidirectional bearing of the input shaft body 84: First bidirectional bearing of the eccentric portion of the input shaft 85: First bidirectional bearing of the gear output shaft 86: Second bidirectional bearing of the gear output shaft 87: First one-way bearing of the gear output shaft 88: Second one-way bearing of the gear output shaft 89: First bidirectional bearing of the reducer output shaft 90: Wave spring A: Reducer force point B: Bearing force point C: Axial direction L: Force span M: Force fulcrum S1: First side S2: Second side S3: Third side DETAILED DESCRIPTION

[0017] Some exemplary embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention is capable of various variations in different embodiments without departing from the scope of the present invention, and that the description and drawings herein are intended to be illustrative, not limiting, of the present invention. For example, different embodiments of the present invention may use repeated reference symbols and / or indicia. This repetition is for the purposes of simplicity and clarity and is not intended to limit the relationship between the various embodiments and / or the described appearance structures. Furthermore, to facilitate descriptions of the relationship between one component or feature in the drawings and another component or features, spatially relative terms such as "right," "left," "inside," "outside," and similar terms may be used. In addition to the orientations shown in the drawings, spatially relative terms are used to encompass different orientations of the device during use or operation. Furthermore, it should be understood that while terms such as "first," "second," and "third" may be used in the claims to describe different components, these components are not limited by these terms. In the embodiments, these components are represented by different component symbols. These terms are used to distinguish between different components. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component without departing from the scope of the embodiment. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0018] Figures 1 to 3 illustrate a power module for an electric power-assisted bicycle according to a first preferred embodiment of the present invention. In this embodiment, the power module for an electric power-assisted bicycle (hereinafter referred to as the power module) 1 is, for example, applied to a mid-mounted structure, and includes a pedal shaft 10, a housing 20, a motor 30, a reducer 40, a geared shaft 50, a first bidirectional bearing 81 for the pedal shaft, a sensor assembly 60, and an encoder assembly 70. The aforementioned mid-mounted structure refers to a power module 1 being disposed between the front and rear wheels of the electric power-assisted bicycle, for example, at the bottom bracket, and is generally used to distinguish it from a hub motor design that is directly disposed on the wheel. In this embodiment, the housing 20 defines a radial direction and an axial direction C, and has a left end cap 21, a middle frame 22, a right end cap 23, and a spacer 24. The left end cap 21, the middle frame 22, and the right end cap 23 are interconnected to form the housing 20 and define the interior space of the housing 20. The spacer 24 extends radially from the inner wall of the middle frame 22 to the interior space of the housing 20. In this way, the partition portion 24 extending radially toward the internal space of the housing 20 further axially divides the internal space of the housing 20 into a motor accommodating portion 201 (as shown in the left space in the accompanying drawings) and a reducer accommodating portion 202 (as shown in the right space). The pedal shaft 10 is accommodated in the housing 20 and passes through the left end cover 21, the middle frame 22 and the right end cover 23 along the axial direction C. The motor 30 is, for example, an outer stator inner rotor type structure and is accommodated in the motor accommodating portion 201. In this embodiment, the stator 31 of the motor 30 is fixed to the first side S1 of the partition portion 24 along the axial direction C (as shown in the left side in the accompanying drawings). In addition, the reducer 40 is accommodated in the reducer accommodating portion 202 and includes a reducer input shaft 41, movable teeth 42, fixed teeth 43 and a reducer output shaft 44. The reducer input shaft 41 has an input shaft body portion 411, an input shaft rotor portion 412, an input shaft eccentric portion 413 and an extension portion 414. The extension portion 414 and the input shaft eccentric portion 413 are respectively disposed at opposite ends of the reducer input shaft 41 along the axial direction C. The input shaft rotor portion 412 is located between the input shaft body portion 411 and the extension portion 414 and is radially connected to the motor output shaft 300 of the motor 30. In some embodiments, the input shaft rotor portion 412 and the motor output shaft 300 may be a shared component, that is, they may be the same component to further reduce the device size, strengthen the structure, and reduce costs. For example, the rotor magnet 32 ​​is annularly disposed on the outer ring wall of the input shaft rotor portion 412 to form the motor output shaft 300. Of course, the present invention is not limited to this. In this embodiment, the input shaft body portion 411 is located between the input shaft rotor portion 412 and the input shaft eccentric portion 413. The input shaft body portion 411 is radially connected to the spacer portion 24. The outer diameter of the input shaft rotor portion 412 is larger than the outer diameter of the input shaft body portion 411, and the outer diameter of the input shaft body portion 411 is larger than the outer diameter of the input shaft eccentric portion 413. Of course, this case is not limited to this.Furthermore, in this embodiment, the extension portion 414 extends along the axial direction C toward the left end cover 21 and is connected to a support portion 210 of the left end cover 21 via the input shaft rear bearing 33. The support portion 210, the input shaft rear bearing 33, and the extension portion 414 are sequentially sleeved from the interior space radially toward the center frame 22, from the inside out. The structure and configuration of the support portion 210 effectively reduces the radial space required for the device.

[0019] In this embodiment, the movable teeth 42 are radially sleeved on the eccentric portion 413 of the input shaft. The fixed teeth 43 are radially sleeved on the movable teeth 42 and are fixed to the second side S2 (right side) of the partition 24. The reducer output shaft 44 is connected to the movable teeth 42 along the axial direction C. The input shaft body 411 is radially connected to the third side S3 (inner side) of the partition 24. The first side S1 and the second side S2 are opposite sides of the partition 24, and the third side S3 is connected between the first side S1 and the second side S2. The geared disc output shaft 50 is accommodated in the housing 20. The reducer output shaft 44 is radially sleeved on the geared disc output shaft 50 via a first one-way bearing 87 of the geared disc output shaft, and the geared disc output shaft 50 is radially sleeved on the first end (right end) of the pedal shaft 10 via a second one-way bearing 88 of the geared disc output shaft. The pedal shaft first two-way bearing 81 is accommodated in the housing 20 and radially sleeved on the second end (left end) of the pedal shaft 10. For example, the sensor assembly 60 of the torque sensor is attached to a portion of the surface of the pedal shaft 10 and is disposed along the axial direction C on one side (right side) of the first bidirectional bearing 81 of the pedal shaft.

[0020] In this embodiment, the motor 30 and reducer 40 are axially arranged and housed within the housing 20. The stator of the motor 30 and the fixed teeth 43 of the reducer 40 are respectively fixed to the axially opposite first and second sides S1, S2, of the partition 24. In this embodiment, the housing 20 of the power module 1 is radially divided into two compartments along the axial direction C by the partition 24, extending radially from the outside to the inside. One compartment is the motor compartment 201, located between the left side of the partition 24 and the left end cap 21, and the other is the reducer compartment 202, located between the right side of the partition 24 and the right end cap 23. The first side S1 (left side) of the partition 24 connects to the stator 31 of the motor 30, the second side S2 (right side) of the partition 24 connects to the fixed teeth 43 (or inner ring teeth) of the reducer 40, and the third side S3 (inner side) of the partition 24 connects to the input shaft body 411 between the motor 30 and the reducer 40. Because the spacer 24 extends from a portion of the housing 20's middle frame 22, a mechanism is provided for the motor components and the reducer components to rest against the housing 20. Furthermore, one end (the left end) of the reducer input shaft 41 comprises the input shaft rotor portion 412 and the extension portion 414, while the other end (the right end) comprises the input shaft eccentric portion 413. In this embodiment, the end face of the input shaft rotor portion 412 is connected to the rotor output shaft of the motor 30, and a first bidirectional bearing 82 and a second bidirectional bearing 83 of the input shaft body are disposed between the input shaft body 411 and the third side S3 of the spacer 24. Specifically, the first bidirectional bearing 82 and the second bidirectional bearing 83 of the input shaft body are connected to the input shaft body 411 on one side and to the third side S3 (inner side) of the spacer 24 of the power module 1 housing 20 on the other side to secure the input shaft body 411, thereby ensuring a stable axis of rotation for the reducer 40 during operation. Furthermore, the second side S2 of the spacer 24 is connected to the fixed teeth 43 of the reducer 40 along the axial direction C, which can further reduce the radial space of the power module 1 compared to the embodiment of the prior art in which the fixed teeth are connected to the shell along the radial direction. The stator 31 of the motor 30 is abutted against the inner wall of the middle frame 22 and the first side S1 of the spacer 24. In addition to a stable connection, more shell contact area can be obtained to improve heat dissipation efficiency. The configuration method of connecting the stator 31 of the motor 30, the fixed teeth 43 of the reducer 40 and the input shaft body 411 of the reducer 40 through the three sides S1, S2 and S3 of the shell spacer 24 can optimize the space utilization of the entire power module 1. Therefore, for example, the sensor component 60 of the torque sensor has space to be connected to the surface of the pedal shaft 10, so that the power module 1 can simultaneously meet the requirements of structural strength, stable rotation axis of the reducer input shaft and stator heat dissipation.

[0021] It is noteworthy that in this embodiment, the extension portion 414 of the reducer input shaft 41 further extends along the axial direction C to the left end cap 21, and is connected to the support portion 210 of the left end cap 21 of the housing 20 via the input shaft rear bearing 33. This increases the load span L formed between the bearing force point B (the left bold arrow in FIG1 ) of the input shaft rear bearing 33 and the load fulcrum M (the connection point between the two bearings 82 and 83 in the accompanying drawings) and is greater than the distance between the reducer force point A (the right bold arrow in the accompanying drawings) and the load fulcrum M. This increases the support strength of the reducer input shaft 41, improves the operational stability of the reducer input shaft 41 when the reducer 40 is subjected to force, and reduces the vibration and noise of the overall power module 1. Of course, the present invention is not limited to this.

[0022] Furthermore, in this embodiment, taking advantage of the radial assembly space freed by the support portion 210, the encoder assembly 70 is further positioned along the axial direction C between the extension portion 414 and the left end cap 21 to measure the rotational speed of the reducer input shaft 41 (i.e., the motor output shaft 300). In this embodiment, the encoder assembly 70 comprises a rotating portion 71 (i.e., the encoder DISC) and a sensing portion 72 (i.e., the read head). The rotating portion 71 is connected to one end (the left end) of the extension portion 414 along the axial direction C. The sensing portion 72 is spatially opposed to the rotating portion 71 and measures the speed and angle of rotation of the reducer input shaft 41 (i.e., the motor output shaft 300). The rotating portion 71 and sensing portion 72 can be assembled on a circuit board, for example. The circuit board corresponding to the sensing portion 72 can be located in the internal space between the left end cap 21 and the motor 30. By positioning the encoder assembly 70 along the axial direction C, radial space within the power module 1 is further reduced, helping to optimize radial space and further meet miniaturization requirements.

[0023] In this embodiment, the power module 1 further includes a driver 73 disposed within the housing 20 along the axial direction C, between the motor 30 and the left end cap 21, and electrically connected to the encoder assembly 70 and the sensor assembly 60. It should be noted that because the support portion 210, the input shaft rear bearing 33, and the extension portion 414 are sequentially arranged radially from the inside to the outside of the internal space, the outer diameter of the support portion 210 is smaller than the inner diameter of the extension portion 414. This helps increase the internal space between the left end cap 21 and the motor 30, thereby increasing the usable space of the device and facilitating the installation of the driver 73 and the axial direction C configuration of the encoder assembly 70. Of course, the present invention is not limited to this embodiment and will not be further described.

[0024] In this embodiment, the power module 1 further includes a chain sprocket 51 radially and concentrically mounted on the outer surface of the sprocket shaft 50. The chain sprocket 51 is configured to transmit auxiliary torque output from the sprocket shaft 50 or provide pedaling torque output when rotated forward by human power, for example, via the chain of the electric power-assisted bicycle to the rear wheel (not shown), thereby propelling the electric power-assisted bicycle forward. The torque output from the sprocket shaft 50 or chain sprocket 51 can be provided, for example, by human power, or by the motor 30 driving the reducer 40 to rotate the sprocket shaft 50, or by both. Of course, the sprocket shaft 50 and chain sprocket 51 in this embodiment can be positioned near the rider's right or left foot, driving the chain and rear wheel to rotate and propel the electric power-assisted bicycle forward. This embodiment is not limited to this embodiment and will not be further described.

[0025] In this embodiment, the power module 1 includes a first bidirectional bearing 82 of the input shaft body and a second bidirectional bearing 83 of the input shaft body, which are arranged in the axial direction C and are respectively radially sleeved between the input shaft body 411 and the third side S3 of the spacer 24, and the second bidirectional bearing 83 of the input shaft body is connected to one end (the right end) of the input shaft rotor 412 along the axial direction C. In addition, in this embodiment, the power module 1 also includes a first bidirectional bearing 84 of the input shaft eccentric portion, which is radially sleeved between the input shaft eccentric portion 413 and the movable tooth 42. The power module 1 also includes a first bidirectional bearing 85 of the gear output shaft and a second bidirectional bearing 86 of the gear output shaft, wherein the first bidirectional bearing 85 of the gear output shaft is radially sleeved between the gear output shaft 50 and the right end cover 23 of the housing 20, and is adjacent to the first one-way bearing 87 of the gear output shaft along the axial direction C. The second sprocket shaft bidirectional bearing 86 is radially sleeved between the sprocket shaft 50 and the pedal shaft 10 and is positioned adjacent to the second sprocket shaft one-way bearing 88 along the axial direction C. In this embodiment, the first sprocket shaft bidirectional bearing 85 and the second sprocket shaft bidirectional bearing 86 restrict movement of the sprocket shaft 50 along the axial direction C. In this embodiment, the power module 1 also includes a first reducer output shaft bidirectional bearing 89, which is radially sleeved between the reducer output shaft 44 and the inner wall of the housing 20, which in this embodiment is located on the right end cover 23.

[0026] In this embodiment, the three sides S1, S2, and S3 of the partition portion 24 of the housing 20 are respectively connected to the stator 31 of the motor 30, the fixed teeth 43 of the reducer 40, and the input shaft body 411 of the reducer 40. This configuration optimizes the space utilization of the entire power module 1, thereby allowing space for the sensor assembly 60 to be placed within the housing 20 and connected to the surface of the pedal shaft 10. In this embodiment, the power source of the reducer 40 is transmitted from the input shaft rotor portion 412, which is connected to the motor rotor or the motor output shaft, to the movable teeth 42 of the reducer 40 via the input shaft eccentric portion 413. When the movable teeth 42 generate rotational power, the gear meshing between the movable teeth 42 and the fixed teeth 43 and the drive of the input shaft eccentric portion 413 cause the movable teeth 42 to produce both orbital and rotational motion. When the movable tooth 42 generates revolution and rotation, the indexing hole 421 of the movable tooth 42 drives the reducer output shaft fixing column 46 through the movable tooth bidirectional bearing 45, so that the reducer output shaft 44 obtains the final rotational power and outputs it.

[0027] It should be noted that while conventional radial motor and reducer configurations and arrangements can reduce axial width, they also require a relatively large outer diameter. The present invention's configuration of motor 30 and reducer 40 along axial direction C only slightly increases volume in axial direction C compared to a radial stacking design. This additional size increase can be absorbed by design changes to the bicycle frame, further reducing the overall volume of power module 1 and making it suitable for mounting on a bicycle frame without creating an obtrusive appearance. Of course, this invention is not limited to this approach.

[0028] On the other hand, in order to meet the needs of miniaturization of the overall volume and optimization of bilateral (pedaling) sensing of the left and right feet, the sensor assembly 60 of the torque sensor is centrally configured. For example, it is arranged on the right side of the pedal shaft two-way bearing 81 but does not contact the pedal shaft two-way bearing 81, and is connected to the pedal shaft 10. Therefore, based on this design, the reducer 40 moves along the axial direction C (to the right as shown in the accompanying drawings) to make way for the sensor assembly 60, thereby forming an axial configuration of the reducer 40 and the motor 30. Compared with the existing motor and reducer, which are radially designed, the reducer 40 can reduce part of the radial space after making way along the axial direction C, and can cooperate with the central design of the sensor assembly 60 (for example, a torque sensor). Since the sensor assembly 60 is connected to the surface of the pedal shaft 10 and is centrally configured, it is connected in series in the torque force flow (transmission) path, so the needs of bilateral (pedaling) sensing optimization can be achieved.

[0029] In this embodiment, when the rider's right foot pedals, inputting a right pedaling torque into the pedal shaft 10, as shown in FIG2 , the force flow is transmitted from the right side of the pedal shaft 10 to the left side, then back to the right side of the pedal shaft 10 through the sensor assembly 60 on the surface of the pedal shaft 10, and finally continues to the right side and is output by the sprocket output shaft 50 and the chain sprocket 51. Because the sensor assembly 60 is connected in series with the torque force flow path, located between the torque input and torque output points, it directly receives the transmitted torque, resulting in high measurement accuracy.

[0030] In this embodiment, when the rider's left foot pedals, inputting a left pedaling torque into the pedal shaft 10, as shown in FIG3 , the force flow is transmitted from the left side of the pedal shaft 10 to the right side of the pedal shaft 10, passing through the sensor assembly 60 on the surface of the pedal shaft 10, and then continuously transmitted to the right, where it is output from the sprocket output shaft 50 and the chain sprocket 51. Because the sensor assembly 60 in this embodiment is also connected in series with the torque force flow path, located between the torque input and torque output points, it directly receives the transmitted torque, resulting in high measurement accuracy. Of course, the present invention is not limited to this embodiment.

[0031] FIG4 discloses the power module of the electric power-assisted bicycle according to the second embodiment of the present invention. In this embodiment, the power module 1a is similar to the power module 1 shown in FIG1 to FIG3 , and the same component numbers represent the same components, structures and functions, which will not be described in detail here. In this embodiment, the power module 1a also includes a wave spring 90, which is arranged along the axial direction C between the input shaft rear bearing 33 and the extension 414 of the reducer input shaft 41. When the input shaft rear bearing 33 (as the motor rotating bearing) is assembled between the support portion 210 of the left end cover 21 and the extension 414 of the reducer input shaft 41 (as the motor rotating shaft), the wave spring 90 can be used to eliminate the assembly gap, which helps to increase the usable space of the driver 73 and further helps the encoder assembly 70 save radial space through the axial C configuration. Of course, the present invention is not limited to this.

[0032] FIG5 discloses the power module of the electric power-assisted bicycle according to the third embodiment of the present invention. In this embodiment, the power module 1b is similar to the power modules 1 and 1a shown in FIG1 to FIG4 , and the same component numbers represent the same components, structures and functions, which will not be described in detail here. In this embodiment, the power module 1b also includes a wave spring 90, which is arranged along the axial direction C between the input shaft rear bearing 33 and the support portion 210 of the left end cover 21. When the input shaft rear bearing 33 (serving as the motor rotating bearing) is assembled between the support portion 210 of the left end cover 21 and the extension portion 414 of the reducer input shaft 41 (serving as the motor rotating shaft), the wave spring 90 can be used to eliminate the assembly gap, which helps to increase the usable space of the driver 73 and further helps the encoder assembly 70 save radial space through the axial C configuration. Of course, the present invention is not limited to this and will not be described in detail.

[0033] In summary, this case provides a power module for a mid-mounted electric power-assisted bicycle in which the motor and the reducer are axially arranged, which can optimize the radial space, meet the requirements of miniaturization and realize optimized measurement of pedal torque. On the other hand, the encoder assembly can save radial space by being axially arranged. The internal space of the shell is divided into an axially arranged motor accommodating portion and a reducer accommodating portion through a partition extending radially from the middle frame of the shell. When the motor and the reducer are axially arranged and sleeved on the pedal shaft, the stator of the motor and the fixed teeth of the reducer can be fixedly connected to the two opposite sides of the partition respectively to achieve alignment installation, improve assembly efficiency, enhance stator heat dissipation, and make the structure stronger. Furthermore, when the axially arranged motor and reducer can transmit the power of the motor to the reducer through a reducer input shaft, one end of the reducer input shaft forms an input shaft rotor portion connected to the rotor (output shaft) of the motor or the motor output shaft, and the other end forms an input shaft eccentric portion connected to the movable teeth of the reducer. The input shaft body portion between the input shaft rotor portion and the input shaft eccentric portion can be further radially connected to the third side of the spacer portion through a bearing, so that the reducer input bearing is close to the spacer portion. Furthermore, the reducer input shaft extends axially and is supported by the support portion of the end cover. Therefore, when the motor drives the reducer to operate, the rotation axis of the reducer input shaft can operate stably. In other words, the stator of the motor is axially abutted against one side of the spacer portion, which can increase the contact area between the stator and the housing and improve the heat dissipation efficiency. The fixed teeth of the reducer are axially abutted against the other side of the spacer portion, which not only facilitates positioning and installation and strengthens the structure, but also can further reduce the radial space of the power module. Furthermore, the end cap support, input shaft rear bearing, and reducer shaft inlet extension are radially arranged sequentially from the inside out. The outer diameter of the support is smaller than the inner diameter of the extension, increasing the usable space between the left end cap and the motor. This facilitates the placement of the driver, circuit board, and other components, as well as the axial arrangement of the encoder assembly. This further optimizes radial space and further meets the miniaturization requirements of the electric-assisted bicycle power module. The motor and reducer are axially arranged on opposite sides of the housing's partition. Compared to a radially stacked design, this increase in axial volume is only slightly increased. This additional size increase can be absorbed by design changes to the bicycle frame, further reducing the overall size of the power module and making it suitable for mounting on a bicycle frame. By connecting the reducer's fixed gear, motor stator, and reducer input shaft body to three sides of the housing's partition, the overall space utilization of the power module is optimized. This allows for the torque sensor to be connected to the pedal shaft for accurate dual-pedal force sensing, while also achieving the aforementioned structural strength, stable reducer input shaft rotation axis, and effective stator heat dissipation. On the other hand, the combination of the input shaft rear bearing (motor rotating bearing) connected to the support part of the left end cover and the extension part of the reducer input shaft (motor rotating shaft) can use a wave spring to eliminate the assembly gap, which helps to increase the usable space of the driver panel and help the encoder assembly save radial space through axial configuration.

[0034] The present invention may be modified in various ways by those skilled in the art, but all of these modifications are within the scope of the appended claims.

Claims

1. A power module for an electric power-assisted bicycle, comprising: A housing, which defines a radial direction and an axial direction, and has an end cover, a middle frame, and a spacer, wherein the end cover is connected to the middle frame to define an internal space, and the spacer extends from the middle frame to the internal space along the radial direction, and divides the internal space into a motor accommodating portion and a reducer accommodating portion along the axial direction, wherein the motor accommodating portion is located between the end cover and the spacer; A pedal shaft is accommodated in the housing and extends along the axial direction to penetrate the end cover; A motor, accommodated in the motor accommodation portion and fixed to the spacing portion along the axial direction; A reducer, accommodated in the reducer accommodating portion and fixed to the spacer portion along the axial direction, and comprising a reducer input shaft, wherein the reducer input shaft comprises an input shaft body portion, an input shaft rotor portion and an extension portion, the input shaft rotor portion is located between the input shaft body portion and the extension portion and is connected to the motor output shaft of the motor along the radial direction, the input shaft body portion is connected to the spacer portion along the radial direction, the extension portion extends toward the end cover along the axial direction, and is connected to the support portion of the end cover through an input shaft rear bearing, wherein the support portion, the input shaft rear bearing and the extension portion are sequentially sleeved from the inner space along the radial direction toward the middle frame from the inside to the outside; A second bidirectional bearing of the pedal shaft is sleeved between the pedal shaft and the support portion along the radial direction; and An encoder assembly is arranged between the extension portion and the end cover along the axial direction. 2 . The power module of the electric assist bicycle according to claim 1 , wherein the encoder assembly has a rotating portion and a sensing portion arranged along the axial direction, and the rotating portion is disposed on the extending portion. 3 . The power module for an electric assist bicycle according to claim 1 , wherein an outer diameter of the support portion is smaller than an inner diameter of the extension portion. 4 . The power module of the electric power-assisted bicycle according to claim 1 , further comprising a wave spring, which is arranged between the input shaft rear bearing and the reducer input shaft along the axial direction. 5 . The power module of the electric assist bicycle according to claim 1 , further comprising a wave spring disposed between the input shaft rear bearing and the support portion along the axial direction. 6 . The power module of the electric-assisted bicycle according to claim 1 , wherein the motor further comprises a stator fixed to the first side of the spacer.

7. The power module of the electric assisted bicycle according to claim 6, wherein the reducer further comprises movable teeth, fixed teeth and a reducer output shaft, the fixed teeth are sleeved with the movable teeth along the radial direction, the fixed teeth are fixed to the second side of the spacer, wherein the first side and the second side are opposite to each other, and wherein the reducer output shaft is connected to the movable teeth along the axial direction.

8. The power module of the electric assisted bicycle according to claim 7, wherein the reducer input shaft also includes an input shaft eccentric portion, the movable teeth are sleeved on the input shaft eccentric portion along the radial direction, the input shaft body is connected to the third side of the spacer portion, and the third side is connected between the first side and the second side.

9. The power module of the electric assisted bicycle according to claim 8, wherein the input shaft body is located between the input shaft rotor and the input shaft eccentric portion, the outer diameter of the input shaft rotor is larger than the outer diameter of the input shaft body, and the outer diameter of the input shaft body is larger than the outer diameter of the input shaft eccentric portion.

10. The power module of the electric assisted bicycle according to claim 8 further includes a first bidirectional bearing of the input shaft body and a second bidirectional bearing of the input shaft body, which are arranged along the axial direction and are respectively sleeved between the input shaft body and the third side of the spacer along the radial direction, and the second bidirectional bearing of the input shaft body is connected to the input shaft rotor part along the axial direction.

11. The power module of the electric power-assisted bicycle according to claim 8 further includes a first bidirectional bearing of the reducer output shaft and a first bidirectional bearing of the eccentric portion of the input shaft, wherein the first bidirectional bearing of the reducer output shaft is sleeved between the reducer output shaft and the housing along the radial direction, and the first bidirectional bearing of the eccentric portion of the input shaft is sleeved between the eccentric portion of the input shaft and the movable tooth along the radial direction.

12. The power module of the electric power-assisted bicycle according to claim 7 further includes a sprocket shaft accommodated in the housing, wherein the reducer output shaft is radially sleeved with the sprocket shaft through a first one-way bearing of the sprocket shaft, and the sprocket shaft is radially sleeved with the pedal shaft through a second one-way bearing of the sprocket shaft.

13. The power module of the electric power-assisted bicycle according to claim 12 further includes a first bidirectional bearing of the sprocket shaft and a second bidirectional bearing of the sprocket shaft for limiting the movement of the sprocket shaft along the axial direction, wherein the first bidirectional bearing of the sprocket shaft is sleeved between the sprocket shaft and the housing along the radial direction, and is adjacent to the first unidirectional bearing of the sprocket shaft along the axial direction, wherein the second bidirectional bearing of the sprocket shaft is sleeved between the sprocket shaft and the pedal shaft along the radial direction, and is adjacent to the second unidirectional bearing of the sprocket shaft along the axial direction. 14 . The power module of the electric power-assisted bicycle according to claim 1 , further comprising a sensor assembly attached to the pedal shaft and arranged on one side of the first bidirectional bearing of the pedal shaft along the axial direction. 15 . The power module of the electric power-assisted bicycle according to claim 1 , further comprising a driver, which is disposed in the housing and located between the motor and the end cover.

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