Large-torque compact booster bicycle mid-motor

Abstract

The utility model discloses a large-torque compact booster bicycle mid-motor, and belongs to the field of booster bicycle mid-motors. The middle motor comprises a casing, a motor assembly, a transmission gear set, a middle shaft, a torque sensor, a large gear and a chain wheel, the middle shaft is a spline head middle shaft, and the torque sensor comprises a shaft sleeve, a moving piece fixed on the shaft sleeve, a static piece oppositely attached to the moving piece and a torque deformation piece arranged on the shaft sleeve. The middle shaft is sleeved with the shaft sleeve and can transmit torque, the end, close to the static part, of the shaft sleeve is located on the inner side of the connecting pipe, the one-way clutch is installed at the other end of the shaft sleeve, and the large gear is installed on the one-way clutch in a sleeved mode. And the high-power and high-torque output requirements of the modified middle motor are met. In addition, the centrally-mounted motor is compact in structure, small in overall occupied space and convenient to install and use on the power-assisted bicycle.

Description

Technical Field

[0001] The utility model relates to a mid-mounted motor, and more particularly to a large-torque compact mid-mounted motor for a power-assisted bicycle. Background Art

[0002] A power-assisted bicycle is a new type of vehicle that uses an electric motor to assist riding. When riding on flat ground, the output power of the motor is very small, which makes people feel easy to ride and saves electricity. However, when going uphill, it can output a large torque to make climbing very effortless. In recent years, it has been loved by many consumers.

[0003] The torque sensor is a key component of a power-assisted bicycle, which can adjust the output power of the motor according to the torque applied to the bicycle's bottom bracket. As people's requirements for the assisted riding power of power-assisted bicycles become higher and higher, especially in Europe and the United States, the ordinary square-head bottom bracket can no longer meet the high-power output requirements, and it is replaced by a spline-head bottom bracket with a larger diameter (i.e., the ISIS bottom bracket). However, since the size of the bicycle's bottom bracket is relatively fixed, as the diameter of the bottom bracket increases, the installation space of the bottom bracket torque sensor is further compressed, and most torque sensors with existing structural designs are difficult to meet the requirements for installation in the bottom bracket. Therefore, most mid-mounted motors that use a spline-head bottom bracket are integrally installed models, and are rarely used in mid-mounted motors suitable for modification, which cannot meet the modification needs of consumers.

[0004] In addition, the existing mid-mounted motors for power-assisted bicycles have the following disadvantages:

[0005] 1. Most existing mid-axle torque sensors directly use strain gauges to detect torque signals, which are then wirelessly transmitted to the motor control module via induction coils. However, due to the small deformation of the strain gauges themselves and the lack of signal amplification, the torque output signal is intermittent at low torque, resulting in very poor stability.

[0006] 2. The secondary transmission gear of the existing mid-mounted motor needs to be supported by an outer bearing. The bearing takes up space in the end cover, which is not conducive to the overall compactness of the mid-mounted motor.

[0007] 3. Most existing mid-mounted motors use Hall sensors to sense the motor shaft position. This type of sensor has poor position accuracy and poor motor operation stability.

[0008] Based on the above problems of the existing mid-mounted motor, it is necessary to design a high-torque compact mid-mounted motor for power-assisted bicycles to meet the installation requirements of the modified mid-mounted motor on the five-way structure of high-power power-assisted bicycles. Summary of the Invention

[0009] 1. Technical problems to be solved by the utility model

[0010] The purpose of the utility model is to overcome the deficiency of the existing mid-mounted motor in that it is difficult to meet the modification requirements of high-power power-assisted bicycles, and to provide a high-torque compact mid-mounted motor for power-assisted bicycles. By adopting the technical solution of the utility model and optimizing the structure of the torque sensor and the like, the purpose of installing a spline head mid-shaft with a larger diameter in the five-way connecting pipe is achieved, thereby meeting the high-power and high-torque output requirements of the modified mid-mounted motor; in addition, the mid-mounted motor has a compact structure and occupies a small space as a whole, which is convenient for installation and use on power-assisted bicycles.

[0011] 2. Technical solution

[0012] In order to achieve the above-mentioned purpose, the technical solution provided by the present utility model is:

[0013] The utility model discloses a mid-mounted motor for a high-torque, compact power-assisted bicycle, comprising a housing, a motor assembly, a transmission gear set, a central shaft, a torque sensor, a large gear, and a sprocket. The housing has a connecting tube, the central shaft is rotatably mounted in the connecting tube, the torque sensor is mounted on the central shaft, the sprocket is coaxially fixed to one side of the large gear, the motor assembly is fixed to the housing, and is meshed with the large gear through the transmission gear set for transmission, the torque sensor is electrically connected to a motor controller for controlling and driving the motor assembly, wherein:

[0014] The central shaft is a spline head central shaft, and the torque sensor includes a sleeve, a moving part fixed on the sleeve, a stationary part arranged to fit relative to the moving part, and a torque deformation plate arranged on the sleeve. The sleeve is sleeved on the central shaft and can transmit torque. The end of the sleeve close to the stationary part is located on the inner side of the connecting tube, and the other end of the sleeve is installed with a one-way clutch, and the large gear is sleeved on the one-way clutch.

[0015] Furthermore, the stationary part is sleeved on the outside of the shaft sleeve and coaxially rotated and installed on the moving part to form an integral structural part. The moving part is provided with a moving side coil for data transmission and power transmission, and a signal operation chip for receiving and calculating the torque signal detected by the torque deformation plate. The moving side coil is electrically connected to the signal operation chip, and the torque deformation plate is electrically connected to the signal operation chip; the stationary part is provided with a stationary side coil for data transmission and power transmission, and a signal amplification chip for amplifying the torque signal, and the stationary side coil is electrically connected to the signal amplification chip; data transmission and power transmission are performed between the moving side coil and the stationary side coil through the principle of wireless induction, and the stationary part is electrically connected to the motor controller through a lead wire.

[0016] Furthermore, the minimum outer diameter D of the central shaft is 20-22 mm; an inner spline is provided on the inner wall of one end of the sleeve located in the connecting tube, an outer spline is provided in the middle of the central shaft, and the sleeve is transmission-connected to the central shaft via the spline.

[0017] Furthermore, the large gear is a helical gear, the outer wall of the central shaft is provided with a circle of shaft shoulder, the inner wall of the connecting tube is provided with a circle of retaining ring, and a number of retaining steel balls for offsetting the axial component of the large gear are provided between the shaft shoulder and the retaining ring.

[0018] Furthermore, the transmission gear set includes an output shaft gear provided on the motor assembly and a secondary gear set in the motor transmission part provided on one side of the casing, the secondary gear set includes an input gear, an output gear, an intermediate shaft sleeve and a one-way bearing, the input gear is coaxially provided on the outside of the intermediate shaft sleeve, the one-way bearing is provided between the input gear and the intermediate shaft sleeve, a socket is provided in the center of the intermediate shaft sleeve, one end of the output gear has a plug rod that can be inserted in the above-mentioned socket and transmit torque, the end of the intermediate shaft sleeve away from the output gear is rotatably supported in the motor transmission part through a tail bearing, an intermediate bearing is provided on the plug rod between the output gear and the intermediate shaft sleeve, and the intermediate bearing is supported on a transmission box cover, and the transmission box cover is fixed on the side of the motor transmission part away from the motor assembly, the input gear is meshed with the output shaft gear, and the output gear is meshed with the large gear through the transmission box cover.

[0019] Furthermore, the motor controller is arranged in a cavity surrounded by the transmission box cover and the motor transmission part, the end of the output shaft gear is provided with a magnet, and the motor controller is provided with a magnetic encoder corresponding to the magnet.

[0020] Furthermore, a breathable membrane is provided on the housing at the motor transmission part.

[0021] Furthermore, a large gear mounting portion is provided at one end of the connecting pipe close to the large gear, and a large gear cover is fixedly mounted on the large gear mounting portion. One side of the large gear has a ring platform, and a first central shaft bearing and a bearing oil seal are provided between the inner side of the ring platform and the central shaft, and a large gear bearing and a large gear oil seal are provided between the outer side of the ring platform and the large gear cover.

[0022] Furthermore, the maximum width distance W formed from the outer side of the large gear mounting portion to the outer side of the large gear cover is no more than 30 mm.

[0023] Furthermore, a locking nut is provided at one end of the connecting pipe away from the large gear, and one end of the locking nut has an external threaded sleeve, which is screwed together with the internal thread at the end of the connecting pipe. One end of the central shaft passes through the locking nut, and a second central shaft bearing and a central shaft oil seal are provided between the locking nut and the central shaft.

[0024] 3. Beneficial effects

[0025] Compared with the existing known technologies, the technical solution provided by the present invention has the following beneficial effects:

[0026] (1) The utility model relates to a compact mid-mounted motor for a high-torque power-assisted bicycle, which includes a housing, a motor assembly, a transmission gear set, a middle shaft, a torque sensor, a large gear and a sprocket. The middle shaft is a splined head middle shaft. The torque sensor includes a shaft sleeve, a moving part fixed on the shaft sleeve, a stationary part arranged to fit relative to the moving part, and a torque deformation plate arranged on the shaft sleeve. The shaft sleeve is sleeved on the middle shaft and can transmit torque. One end of the shaft sleeve close to the stationary part is located on the inner side of the connecting tube. The other end of the shaft sleeve is equipped with a one-way clutch. The large gear is sleeved on the one-way clutch. By optimizing the structure of the torque sensor and other structures, the purpose of installing a splined head middle shaft with a larger diameter in the five-way connecting tube is achieved, thereby meeting the high power and high torque output requirements of the modified mid-mounted motor.

[0027] (2) The utility model is a large-torque compact power-assisted bicycle mid-mounted motor, in which the stationary part of the torque sensor is sleeved on the outside of the shaft sleeve and coaxially rotated and installed on the moving part to form an integral structural part. The entire torque sensor is self-contained, compact in structure, and easy to install; and the moving part is provided with a moving side coil for data transmission and power transmission, and a signal operation chip for receiving and operating the torque signal detected by the torque deformation plate, and the stationary part is provided with a stationary side coil for data transmission and power transmission, and a signal amplification chip for amplifying the torque signal. The modulation and demodulation of the chip are used to realize the amplification and transmission of the torque signal, which greatly improves the output stability of the torque signal and improves the accuracy and stability of the mid-mounted motor control;

[0028] (3) The utility model is a compact mid-mounted motor for power-assisted bicycles with high torque, wherein the minimum outer diameter D of the shaft is 20 to 22 mm, which can improve the output torque of the mid-mounted motor and meet the modification needs of high-power power-assisted bicycles; the inner wall of one end of the sleeve located in the connecting tube is provided with an internal spline, and the middle part of the middle shaft is provided with an external spline. The sleeve is connected to the middle shaft through the spline, and the transmission is stable and reliable, the transmission torque is large, and the assembly is simple and convenient;

[0029] (4) The utility model is a large torque compact power-assisted bicycle mid-mounted motor, wherein the large gear is a helical gear, the outer wall of the central shaft is provided with a circle of shaft shoulder, the inner wall of the connecting tube is provided with a circle of retaining ring, and a number of retaining steel balls for offsetting the axial component of the large gear are provided between the shaft shoulder and the retaining ring. The helical gear transmission has a compact structure, stable transmission, low transmission noise and vibration, and can meet the needs of large torque transmission;

[0030] (5) The utility model is a mid-mounted motor for a high-torque compact power-assisted bicycle, whose transmission gear set includes an output shaft gear arranged on the motor assembly and a secondary gear set in the motor transmission part arranged on one side of the housing. The secondary gear set includes an input gear, an output gear, an intermediate shaft sleeve and a one-way bearing. A socket is provided in the center of the intermediate shaft sleeve, and one end of the output gear has a plug rod that can be plugged into the above-mentioned socket and transmit torque. The split assembly structure of the intermediate shaft sleeve and the output gear is adopted, so that the support bearing of the output gear can be set in the middle position, which takes up little space and further improves the structural compactness of the mid-mounted motor.

[0031] (6) The utility model is a mid-mounted motor for a high-torque, compact power-assisted bicycle, wherein the motor controller is arranged in a cavity enclosed by a transmission case cover and a motor transmission part, a magnet is provided at the end of the output shaft gear, and a magnetic encoder is provided on the motor controller that corresponds to the magnet. The magnetic encoder is used to replace the original Hall sensor, which has higher position detection accuracy, improves the efficiency of the motor when it is just started, and improves the stability and control accuracy of the operation;

[0032] (7) The utility model is a compact mid-mounted motor for power-assisted bicycles with large torque. A breathable membrane is provided on the motor housing at the motor transmission part, which can effectively balance the internal and external pressures of the mid-mounted motor, prevent external moisture from entering the interior, thereby damaging the electronic control part and the motion bearing, and improve the working stability and service life of the mid-mounted motor.

[0033] (8) The utility model is a large torque compact power-assisted bicycle mid-mounted motor, wherein a large gear mounting portion is provided at one end of the connecting pipe close to the large gear, a large gear cover is fixedly mounted on the large gear mounting portion, a ring platform is provided on one side of the large gear, a first middle shaft bearing and a bearing oil seal are provided between the inner side of the ring platform and the middle shaft, and a large gear bearing and a large gear oil seal are provided between the outer side of the ring platform and the large gear cover, thereby ensuring the working stability of the mid-mounted motor; in addition, the maximum width distance W formed from the outer side of the large gear mounting portion to the outer side of the large gear cover is no more than 30 mm, thereby further ensuring the compactness of the mid-mounted motor structure and facilitating the installation and use of the front sprocket and the rear sprocket in various power-assisted bicycles;

[0034] (9) The utility model is a large-torque compact power-assisted bicycle mid-mounted motor, wherein a locking nut is provided at one end of the connecting pipe away from the large gear, and one end of the locking nut has an external threaded sleeve, which is screwed and connected to the internal thread of the end of the connecting pipe, and one end of the middle shaft passes through the locking nut, and a second middle shaft bearing and a middle shaft oil seal are provided between the locking nut and the middle shaft. By adopting the above-mentioned locking nut, the middle shaft bearing and the oil seal can be installed with the help of the locking nut, which solves the problem that it is difficult to install the bearing and the oil seal in the connecting pipe of the middle shaft with a large diameter spline head. It can be used for the installation of the mid-mounted motor on the five-way pipe and can also facilitate the assembly and production of the mid-mounted motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the three-dimensional structure of a compact mid-mounted motor for a high-torque power-assisted bicycle according to the present invention;

[0036] Figure 2 This is an exploded view of a high-torque, compact mid-mounted motor for power-assisted bicycles according to the present invention;

[0037] Figure 3 This is a side view of the structure of a compact mid-mounted motor for a high-torque power-assisted bicycle according to the present invention;

[0038] Figure 4 for Figure 3 Rotated cross-sectional view in the AA direction;

[0039] Figure 5 This is a plan view of the installation structure of the torque sensor and the large gear on the central shaft in the utility model;

[0040] Figure 6 This is a schematic diagram of the split structure of the torque sensor, large gear and central shaft in the utility model;

[0041] Figure 7 for Figure 5 Cross-sectional view in the middle BB direction;

[0042] Figure 8 This is a schematic structural diagram of the secondary gear set in the present utility model;

[0043] Figure 9 for Figure 8 Cross-sectional view in CC direction.

[0044] Explanation of the numbers in the schematic diagram:

[0045] 1. Casing; 1-1. Connecting pipe; 1-2. Motor transmission unit; 1-2a. Breathable membrane; 1-3. Large gear mounting unit; 2. Motor assembly; 2-1. Stator assembly; 2-2. Rotor assembly; 2-3. Output shaft gear; 3. Transmission case cover; 4. Sprocket; 5. Center shaft; 5-1. External spline; 6. Lock nut; 7. Secondary gear set; 7-1. Input gear; 7-2. Output gear; 7-3. Intermediate bearing; 7-4. Tail bearing; 7-5. Intermediate bushing; 7-6. One-way bearing; 8. Torque sensor; 8-1. Bushing; 8 -1a, internal spline; 8-1b, extension section; 8-2, moving part; 8-2a, moving side coil; 8-2b, signal operation chip; 8-3, stationary part; 8-3a, stationary side coil; 8-3b, signal amplification chip; 8-4, torque deformation plate; 9, one-way clutch; 10, large gear; 11, large gear cover; 12, large gear bearing; 13, first middle shaft bearing; 14, large gear oil seal; 15, magnet; 16, motor controller; 17, second middle shaft bearing; 18, middle shaft oil seal; 19, reinforcement plate; 20, retaining steel ball. DETAILED DESCRIPTION

[0046] In order to further understand the content of the present invention, the present invention is described in detail with reference to the accompanying drawings and embodiments.

[0047] [Example]

[0048] Combine Figures 1 to 6 As shown, a high-torque compact power-assisted bicycle mid-mounted motor of this embodiment includes a housing 1, a motor assembly 2, a transmission gear set, a central shaft 5, a torque sensor 8, a large gear 10 and a sprocket 4. The housing 1 has a connecting tube 1-1, which is used to be installed in the five-way pipe of the bicycle. The central shaft 5 is rotatably installed in the connecting tube 1-1. The torque sensor 8 is installed on the central shaft 5. The sprocket 4 is coaxially fixed on one side of the large gear 10. The motor assembly 2 is fixed on the housing 1 and is meshed with the large gear 10 through the transmission gear set. The torque sensor 8 is electrically connected to the motor controller 16 for controlling and driving the motor assembly 2. Among them, the central shaft 5 is a spline head central shaft, that is, both ends of the central shaft 5 have external splines for connecting to the pedal rocker arm, and its diameter is larger than the original square head central shaft. As shown Figure 6 As shown, the torque sensor 8 includes a sleeve 8-1, a moving part 8-2 fixed on the sleeve 8-1, a stationary part 8-3 arranged in relative contact with the moving part 8-2, and a torque deformation piece 8-4 arranged on the sleeve 8-1. The sleeve 8-1 is sleeved on the middle shaft 5 and can transmit torque. When riding, the torque generated by the middle shaft 5 is transmitted to the sleeve 8-1 and detected by the torque deformation piece 8-4. The torque signal detected by the torque deformation piece 8-4 is transmitted to the motor controller 16 through the moving part 8-2 and the stationary part 8-3, and the motor assembly 2 is controlled to provide riding assistance according to the torque size. Figures 4 to 7As shown, the end of the sleeve 8-1 close to the stationary part 8-3 is located on the inner side of the connecting tube 1-1, and the other end of the sleeve 8-1 is installed with a one-way clutch 9, and the large gear 10 is mounted on the one-way clutch 9. During normal riding, the middle shaft 5 can drive the large gear 10 to rotate together through the one-way clutch 9, thereby driving the sprocket 4 to rotate; when the middle shaft 5 reverses or the motor assembly 2 drives the large gear 10 to rotate, the middle shaft 5 and the large gear 10 can be disengaged from each other and no longer transmit speed and torque. The one-way clutch 9 is arranged on the sleeve 8-1, and the large gear 10 is mounted on the one-way clutch 9, so that the structure of this part is more compact and the overall thickness can be made thinner, which is conducive to reducing the weight of the mid-mounted motor and facilitating installation on the bicycle. The above-mentioned mid-mounted motor, by optimizing the structure of the torque sensor and other structures, achieves the purpose of installing a spline head middle shaft with a larger diameter in the five-way connecting tube, meeting the high power and high torque output requirements of the modified mid-mounted motor.

[0049] In the torque sensor 8, the moving part 8-2 can rotate with the sleeve 8-1, while the stationary part 8-3 is relatively stationary. The coil chip group in the moving part 8-2 and the stationary part 8-3 is used to realize the processing and transmission of the torque signal. Figure 7 As shown, in this embodiment, the stationary member 8-3 is sleeved on the outside of the sleeve 8-1 and coaxially rotated on the moving member 8-2 to form an integral structure. The entire torque sensor is self-contained, compact, and easy to install. Specifically, the moving member 8-2 and the stationary member 8-3 are interlocked and connected, allowing for relative rotation. This ensures the integrity and compactness of the moving member 8-2 and the stationary member 8-3, facilitates integrated installation and use, and reduces the probability of reduced signal transmission stability due to installation errors and other factors in existing split installation structures, further ensuring the transmission stability of the torque signal. The moving element 8-2 is equipped with a moving-side coil 8-2a for data transmission and power transfer, and a signal calculation chip 8-2b for receiving and calculating the torque signal detected by the torque deformation plate 8-4. The moving-side coil 8-2a is electrically connected to the signal calculation chip 8-2b, and the torque deformation plate 8-4 is electrically connected to the signal calculation chip 8-2b. The stationary element 8-3 is equipped with a stationary-side coil 8-3a for data transmission and power transfer, and a signal amplification chip 8-3b for amplifying the torque signal. The stationary coil 8-3a is electrically connected to the signal amplification chip 8-3b. Data transmission and power transfer are performed between the moving-side coil 8-2a and the stationary coil 8-3a via wireless induction principles. The stationary element 8-3 is electrically connected to the motor controller 16 via lead wires. By providing the signal calculation chip 8-2b and the signal amplification chip 8-3b, the torque signal is amplified and transmitted through modulation and demodulation of the chips, greatly improving the stability of the torque signal output and the accuracy and stability of the central motor control.

[0050] like Figure 6and Figure 7 As shown, in this embodiment, the minimum outer diameter D of the central shaft 5 is 20-22 mm, which can increase the output torque of the mid-mounted motor and meet the needs of high-power power-assisted bicycle modifications. The inner wall of the sleeve 8-1, located within the connecting tube 1-1, is provided with internal splines 8-1a. The central portion of the central shaft 5 is provided with external splines 5-1. The sleeve 8-1 is connected to the central shaft 5 via the splines, providing stable and reliable transmission, high transmission torque, and simple and convenient assembly. To facilitate the installation of the one-way clutch 9, an extension section 8-1b for mounting the one-way clutch 9 is provided on the end of the sleeve 8-1 away from the internal splines 8-1a. The one-way clutch 9 can be a one-way ratchet clutch. The extension section 8-1b is integrated with the shaft sleeve 8-1. During normal riding, the middle shaft 5 drives the shaft sleeve 8-1 to rotate together. At this time, the one-way clutch 9 combines the extension section 8-1b with the large gear 10, thereby driving the large gear 10 to rotate together. When the motor is assisted, the motor assembly 2 directly drives the large gear 10 to rotate. At this time, the reverse rotation of the shaft sleeve 8-1 and the large gear 10 is separated by the one-way clutch 9, achieving a riding assist effect. Figure 4 As shown, in this embodiment, the large gear 10 is a helical gear, which has the advantages of compact structure, smooth transmission, low transmission noise and vibration, and can meet the needs of high-torque transmission. To overcome the axial force component of the helical gear, a shaft shoulder is provided on the outer wall of the central shaft 5, and a retaining ring is provided on the inner wall of the connecting tube 1-1. A number of retaining steel balls 20 are also provided between the shaft shoulder and the retaining ring to offset the axial force component of the large gear 10. The retaining steel balls 20 can provide axial reverse thrust, which can ensure the smooth rotation of the central shaft 5 and reduce friction between the central shaft 5 and the connecting tube 1-1.

[0051] like Figure 2 and Figure 4 And refer to Figure 8 and Figure 9As shown, in this embodiment, the transmission gear set includes an output shaft gear 2-3 provided on the motor assembly 2 and a secondary gear set 7 provided in the motor transmission part 1-2 on one side of the housing 1. The secondary gear set 7 includes an input gear 7-1, an output gear 7-2, an intermediate shaft sleeve 7-5 and a one-way bearing 7-6. The input gear 7-1 is coaxially provided on the outside of the intermediate shaft sleeve 7-5. The one-way bearing 7-6 is provided between the input gear 7-1 and the intermediate shaft sleeve 7-5. A socket is provided at the center of the intermediate shaft sleeve 7-5. One end of the output gear 7-2 has a plug rod that can be plugged into the above-mentioned socket and transmit torque. The plug rod A spline structure is preferably used for connection with the jack, although a flat key or other non-circular cross-section plug-in transmission can also be used. The end of the intermediate sleeve 7-5 away from the output gear 7-2 is rotatably supported within the motor transmission part 1-2 via the tail bearing 7-4. An intermediate bearing 7-3 is provided on the insertion rod between the output gear 7-2 and the intermediate sleeve 7-5. The intermediate bearing 7-3 is supported on the transmission box cover 3, which is fixed to the side of the motor transmission part 1-2 away from the motor assembly 2. The input gear 7-1 meshes with the output shaft gear 2-3, and the output gear 7-2 passes through the transmission box cover 3 and meshes with the large gear 10. The split assembly structure of the intermediate sleeve 7-5 and the output gear 7-2 allows the support bearing of the output gear 7-2 to be located in the middle position, taking up less space and further improving the structural compactness of the mid-mounted motor. During normal riding, the middle shaft 5 drives the large gear 10 to rotate, and the large gear 10 drives the output gear 7-2 meshing with it to rotate. Due to the setting of the one-way bearing 7-6, the intermediate shaft sleeve 7-5 and the input gear 7-1 are separated at this time, so it will not drive the input gear 7-1 to rotate, and thus will not drive the motor assembly 2 to passively rotate. During assisted riding, the motor assembly 2 drives the output shaft gear 2-3 to rotate, and the output shaft gear 2-3 drives the input gear 7-1 to rotate. At this time, the input gear 7-1 and the intermediate shaft sleeve 7-5 are combined together through the one-way bearing 7-6, so they can drive the intermediate shaft sleeve 7-5 and the output gear 7-2 to rotate together, and the output gear 7-2 drives the large gear 10 meshing with it to rotate, thereby providing riding assistance. Figure 1 As shown, in this embodiment, a breathable membrane 1-2a is further provided on the housing 1 at the motor transmission portion 1-2. This effectively balances the internal and external pressures of the center motor, preventing external moisture from entering and damaging the electronic control unit and moving bearings, thereby improving the operating stability and service life of the center motor. The motor assembly 2 is primarily composed of a stator assembly 2-1 and a rotor assembly 2-2. The rotor assembly 2-2 is mounted inside the stator assembly 2-1. The outer housing of the stator assembly 2-1 is fixed to the motor transmission portion 1-2. The output shaft gear 2-3 is mounted on the rotating shaft of the rotor assembly 2-2.

[0052] like Figure 2 and Figure 4As shown, in this embodiment, the motor controller 16 is housed within the cavity enclosed by the transmission case cover 3 and the motor transmission unit 1-2. To facilitate installation in confined spaces, the motor controller 16 is divided into a motor control module and a motor drive module. These modules are mounted one above the other within the cavity, enhancing the compactness of the structure. A magnet 15 is positioned at the end of the output shaft gear 2-3, and the motor controller 16 is equipped with a magnetic encoder that mates with the magnet 15. This replacement of the conventional Hall effect sensor provides higher position detection accuracy, improving motor efficiency during initial startup, operational stability, and control accuracy.

[0053] catch Figure 2 and Figure 4 As shown, the end of the connecting pipe 1-1 close to the large gear 10 is provided with a large gear mounting portion 1-3, the stationary member 8-3 can be fixed on the inner wall of the large gear mounting portion 1-3, and a large gear cover 11 is fixedly installed on the large gear mounting portion 1-3. The large gear cover 11 also covers the output gear 7-2. One side of the large gear 10 has a ring platform (such as Figure 7 As shown in FIG, a first middle shaft bearing 13 and a bearing oil seal are provided between the inner side of the ring platform and the middle shaft 5, and a large gear bearing 12 and a large gear oil seal 14 are provided between the outer side of the ring platform and the large gear cover 11, thereby ensuring the working stability of the middle motor. The large gear 10 with the above structure makes the structure of the middle motor more compact, as shown in FIG. Figure 4 As shown, the maximum width distance W formed from the outer side of the large gear mounting portion 1-3 to the outer side of the large gear cover 11 is no more than 30 mm, which further ensures the compactness of the structure of the mid-mounted motor and facilitates the installation and use of the front and rear sprockets in various power-assisted bicycles.

[0054] Further references Figure 2 and Figure 4 As shown, a locking nut 6 is further provided at the end of the connecting tube 1-1 away from the large gear 10. One end of the locking nut 6 has an external threaded sleeve, which is screwed together with the internal thread of the end of the connecting tube 1-1. One end of the central shaft 5 passes through the locking nut 6. A second central shaft bearing 17 and a central shaft oil seal 18 are further provided between the locking nut 6 and the central shaft 5. By adopting the above-mentioned locking nut 6, the central shaft bearing and oil seal can be installed with the help of the locking nut 6, which solves the problem of great difficulty in installing bearings and oil seals on the central shaft with a large diameter spline head in the connecting tube 1-1. It can be used for the installation of the mid-mounted motor on the five-way pipe and can also facilitate the assembly and production of the mid-mounted motor. In order to improve the installation reliability of the mid-mounted motor, a reinforcing plate 19 is further provided at the end of the connecting tube 1-1 near the locking nut 6. The reinforcing plate 19 is connected to the motor assembly 2.

[0055] The utility model discloses a high-torque compact mid-mounted motor for power-assisted bicycles. By optimizing the structure of the torque sensor and other parts, the purpose of installing a spline head mid-shaft with a larger diameter in the five-way connecting pipe is achieved, thereby meeting the high-power and high-torque output requirements of the modified mid-mounted motor. In addition, the mid-mounted motor has a compact structure and occupies a small space as a whole, which is convenient for installation and use on power-assisted bicycles.

[0056] The above schematically describes the present invention and its embodiments, which is not intended to be limiting. The accompanying drawings illustrate only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by this and, without departing from the spirit of the present invention, uninventively designs structures and embodiments similar to this technical solution, they shall fall within the scope of protection of the present invention.

Claims

1. A high-torque compact mid-mounted motor for a power-assisted bicycle, comprising a housing (1), a motor assembly (2), a transmission gear set, a middle shaft (5), a torque sensor (8), a large gear (10) and a sprocket (4), wherein the housing (1) has a connecting tube (1-1), the middle shaft (5) is rotatably mounted in the connecting tube (1-1), the torque sensor (8) is mounted on the middle shaft (5), the sprocket (4) is coaxially fixed to one side of the large gear (10), the motor assembly (2) is fixed to the housing (1) and meshes with the large gear (10) through the transmission gear set, the torque sensor (8) is electrically connected to a motor controller (16) for controlling and driving the motor assembly (2), and is characterized in that: The central shaft (5) is a spline head central shaft. The torque sensor (8) comprises a sleeve (8-1), a moving part (8-2) fixed on the sleeve (8-1), a stationary part (8-3) arranged in contact with the moving part (8-2), and a torque deformation plate (8-4) arranged on the sleeve (8-1). The sleeve (8-1) is sleeved on the central shaft (5) and is capable of transmitting torque. One end of the sleeve (8-1) close to the stationary part (8-3) is located inside the connecting pipe (1-1). A one-way clutch (9) is installed on the other end of the sleeve (8-1). The large gear (10) is sleeved on the one-way clutch (9).

2. The high-torque compact mid-mounted motor for power-assisted bicycle according to claim 1, characterized in that: The stationary part (8-3) is sleeved on the outside of the shaft sleeve (8-1) and coaxially rotated on the moving part (8-2) to form an integral structural part. The moving part (8-2) is provided with a moving side coil (8-2a) for data transmission and power transmission, and a signal operation chip (8-2b) for receiving and operating the torque signal detected by the torque deformation sheet (8-4). The moving side coil (8-2a) is electrically connected to the signal operation chip (8-2b), and the torque deformation sheet (8-4) is electrically connected to the signal operation chip (8-2b). -2b); the stationary part (8-3) is provided with a stationary side coil (8-3a) for data transmission and power transmission, and a signal amplification chip (8-3b) for amplifying the torque signal, and the stationary side coil (8-3a) is electrically connected to the signal amplification chip (8-3b); the moving side coil (8-2a) and the stationary side coil (8-3a) perform data transmission and power transmission via the wireless induction principle, and the stationary part (8-3) is electrically connected to the motor controller (16) via a lead wire.

3. The high-torque compact mid-mounted motor for power-assisted bicycle according to claim 2, characterized in that: The minimum outer diameter D of the central shaft (5) is 20 to 22 mm; an inner spline (8-1a) is provided on the inner wall of one end of the sleeve (8-1) located in the connecting tube (1-1); an outer spline (5-1) is provided in the middle of the central shaft (5); and the sleeve (8-1) is transmission-connected to the central shaft (5) via the spline.

4. The high-torque compact mid-mounted motor for power-assisted bicycle according to claim 3, characterized in that: The large gear (10) is a helical gear, the outer wall of the central shaft (5) is provided with a circle of shaft shoulder, the inner wall of the connecting tube (1-1) is provided with a circle of retaining ring, and a plurality of retaining steel balls (20) for offsetting the axial component force of the large gear (10) are provided between the shaft shoulder and the retaining ring.

5. The high-torque compact mid-mounted motor for power-assisted bicycle according to any one of claims 1 to 4, characterized in that: The transmission gear set comprises an output shaft gear (2-3) provided on the motor assembly (2) and a secondary gear set (7) provided in the motor transmission part (1-2) on one side of the housing (1). The secondary gear set (7) comprises an input gear (7-1), an output gear (7-2), an intermediate shaft sleeve (7-5) and a one-way bearing (7-6). The input gear (7-1) is coaxially provided on the outside of the intermediate shaft sleeve (7-5). The one-way bearing (7-6) is provided between the input gear (7-1) and the intermediate shaft sleeve (7-5). The center of the intermediate shaft sleeve (7-5) is provided with a socket. One end of the output gear (7-2) has a socket capable of being plugged into the above-mentioned The invention relates to a plug rod which is inserted into the jack and transmits torque. The end of the intermediate sleeve (7-5) away from the output gear (7-2) is rotatably supported in the motor transmission part (1-2) through the tail bearing (7-4). An intermediate bearing (7-3) is provided on the plug rod between the output gear (7-2) and the intermediate sleeve (7-5). The intermediate bearing (7-3) is supported on the transmission box cover (3). The transmission box cover (3) is fixed to the side of the motor transmission part (1-2) away from the motor assembly (2). The input gear (7-1) is meshed with the output shaft gear (2-3). The output gear (7-2) passes through the transmission box cover (3) and is meshed with the large gear (10).

6. The high-torque compact mid-mounted motor for power-assisted bicycle according to claim 5, characterized in that: The motor controller (16) is arranged in a cavity surrounded by the transmission box cover (3) and the motor transmission part (1-2); a magnet (15) is provided at the end of the output shaft gear (2-3); and a magnetic encoder corresponding to the magnet (15) is provided on the motor controller (16).

7. The high-torque compact mid-mounted motor for power-assisted bicycle according to claim 5, characterized in that: A breathable membrane (1-2a) is also provided on the housing (1) at the motor transmission part (1-2).

8. The high-torque compact mid-mounted motor for power-assisted bicycle according to any one of claims 1 to 4, characterized in that: A large gear mounting portion (1-3) is provided at one end of the connecting pipe (1-1) close to the large gear (10), a large gear cover (11) is fixedly mounted on the large gear mounting portion (1-3), a ring platform is provided on one side of the large gear (10), a first central shaft bearing (13) and a bearing oil seal are provided between the inner side of the ring platform and the central shaft (5), and a large gear bearing (12) and a large gear oil seal (14) are provided between the outer side of the ring platform and the large gear cover (11).

9. The high-torque compact mid-mounted motor for power-assisted bicycle according to claim 8, characterized in that: The maximum width distance W formed from the outer side of the large gear mounting portion (1-3) to the outer side of the large gear cover (11) is no greater than 30 mm.

10. The high-torque compact mid-mounted motor for power-assisted bicycle according to any one of claims 1 to 4, characterized in that: The end of the connecting pipe (1-1) away from the large gear (10) is also provided with a locking nut (6), one end of the locking nut (6) has an external threaded sleeve, and the external threaded sleeve is screwed and connected to the internal thread of the end of the connecting pipe (1-1). One end of the central shaft (5) passes through the locking nut (6), and a second central shaft bearing (17) and a central shaft oil seal (18) are also provided between the locking nut (6) and the central shaft (5).

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