Magnetic transmission deceleration mid-motor for power-assisted bicycle

Abstract

The utility model discloses a magnetic transmission deceleration mid-motor for a power-assisted bicycle, and belongs to the power-assisted technology of bicycles. When an existing centrally-mounted motor is assembled, a cylindrical rotor shaft is eccentric due to the action of a constant magnetic field, the assembly difficulty is increased, and the assembly precision of a product is reduced. According to the utility model, the first rotor and the second rotor are separately configured and are coaxially assembled together through the torsion transmission structure, so that the second rotor drives the first rotor to synchronously rotate; the machine shell is formed by axially butting a first shell body and a second shell body on the radial outer side of the torsion transmission structure. During assembly, the first rotor and the second rotor can be assembled in place, the eccentric influence of the first rotor and the second rotor is reduced, then the first rotor and the second rotor are in coaxial butt joint through the torsion transmission structure, eccentricity of the first rotor and the second rotor caused by the action of a magnetic field is reduced, and assembly is easy. The assembling difficulty is reduced, and the assembling precision of products and the assembling consistency of batch products are guaranteed.

Description

Technical Field

[0001] The utility model belongs to the assisting technology of the mid-drive motor of a power-assisted bicycle, and particularly relates to a magnetic drive reduction mid-drive motor for a power-assisted bicycle. Background Art

[0002] The invention patent application with the publication number of CN118554721A applied by the applicant discloses a magnetic drive reduction device and a mid-drive motor of a power-assisted bicycle. In this mid-drive motor, a first rotor and a second rotor are jointly arranged on the same cylindrical rotor shaft, and the cylindrical rotor shaft is sleeved on the radial outer side of the torque assembly, so as to simplify the structures of the first rotor and the second rotor and increase the concentricity of the first rotor and the second rotor. However, since the first stator, the first rotor and the second rotor have a constant magnetic field during assembly, the cylindrical rotor shaft will be eccentric due to the action of the constant magnetic field during assembly. For example, after one end of the cylindrical rotor shaft located in the motor part is assembled, the other end of the cylindrical rotor shaft is eccentric due to the action of the magnetic field, increasing the assembly difficulty. The eccentric first rotor will also contact the modulation ring and apply a radial thrust to the modulation ring, resulting in the eccentricity of the modulation ring. Forcing the correction by external force and implementing the assembly in the foregoing eccentric state will cause the mutual collision and damage of the first rotor and the modulation ring, and the modulation ring and the first stator, ultimately affecting the assembly accuracy of the product. Content of the Utility Model

[0003] The technical problem to be solved and the technical task proposed by the utility model is to overcome the defect that the first rotor and the second rotor of the existing mid-drive motor are jointly arranged on the same cylindrical rotor shaft, which will cause the cylindrical rotor shaft to be eccentric due to the action of the constant magnetic field during assembly, increase the assembly difficulty and reduce the assembly accuracy of the product, and provide a magnetic drive reduction mid-drive motor for a power-assisted bicycle, aiming to reduce the assembly difficulty, ensure the assembly accuracy of the product and the consistency of the assembly of batch products.

[0004] To achieve the above object, the magnetic drive reduction mid-drive motor for a power-assisted bicycle of the utility model comprises:

[0005] A housing;

[0006] A torque assembly, which penetrates through the housing and its two ends extend out of the housing to receive an external torque;

[0007] A magnetic drive reduction device, which comprises a first stator, a first rotor and a modulation ring;

[0008] A motor part, which comprises a second stator and a second rotor;

[0009] A bi-directional clutch is disposed between a torque component and a modulation ring and is used to alternatively transfer torque from the torque component to it or from the modulation ring to it. The bi-directional clutch has a cylindrical output shaft extending out of the housing for outputting torque, and the cylindrical output shaft is sleeved on the radial outer side of one end of the torque component.

[0010] It is characterized in that: the first rotor and the second rotor are separately disposed and coaxially assembled together through a torque transmission structure so that the second rotor drives the first rotor to rotate synchronously.

[0011] For this in-wheel motor, since the first rotor and the second rotor are separately disposed and coaxially assembled through a torque transmission structure, during assembly, the first rotor and the second rotor can be assembled in place respectively, reducing the eccentric influence of the first rotor and the second rotor. Then, they are coaxially docked through the torque transmission structure, reducing the eccentricity caused by the magnetic field acting on the first rotor and the second rotor, and being easy to assemble. After the eccentric influence of the first rotor is reduced, the probability of the first rotor contacting the modulation ring and applying a radial thrust to the modulation ring is reduced, reducing the influence of the magnetic field on the modulation ring. When the first rotor and the second rotor are coaxially docked through the torque transmission structure, external force intervention for forced alignment can be reduced, reducing the probability of damage caused by the mutual collision between the first rotor and the modulation ring, and between the modulation ring and the first stator, reducing the assembly difficulty, and ensuring the assembly accuracy of the product and the consistency of the assembly of mass-produced products.

[0012] Preferably, the torque transmission structure is a spline transmission structure. The concentricity of spline transmission is good. Splines are easy to manufacture and install, do not require additional parts, and are convenient for assembly. The contact surface of spline transmission is very large, having the advantages of strong load-bearing capacity, high transmission efficiency, low noise, and long service life. Moreover, spline transmission avoids loosening and has very high reliability. The connection of spline transmission uses linear frictional force transmission, so the load-bearing capacity is very strong. Especially under torque and impact loads, the transmission capacity of spline transmission is more prominent. The working process of spline transmission does not generate vibration and impact, so it works smoothly and can ensure the stability of transmission.

[0013] Preferably, the first rotor includes a first cylindrical rotor shaft and a first rotor magnetic pole assembly attached to the first cylindrical rotor shaft; the second rotor includes a second cylindrical rotor shaft and a second rotor magnetic pole assembly attached to the second cylindrical rotor shaft; the first cylindrical rotor shaft and the second cylindrical rotor shaft are coaxially assembled through a torque transmission structure. Accordingly, the attachment of the first rotor magnetic pole assembly to the first cylindrical rotor shaft and the attachment of the second rotor magnetic pole assembly to the second cylindrical rotor shaft do not affect each other, enabling the first rotor and the second rotor assembled together to maintain better transmission.

[0014] Preferably, the first cylindrical rotor shaft sleeve is disposed radially outside the two-way clutch, and a bearing is assembled between the two to maintain their rotational fit. This not only achieves the radial support of the first cylindrical rotor shaft but also ensures the action relationship between the first cylindrical rotor shaft and the two-way clutch.

[0015] Preferably, the two-way clutch includes an inner sleeve, an outer sleeve, a plurality of first clutch members, and a plurality of second clutch members. The inner sleeve is disposed in the torque assembly and rotates with the torque assembly. The outer sleeve is disposed in the modulation ring and rotates with the modulation ring. The cylindrical output shaft sleeve is radially outside the inner sleeve, and the outer sleeve is sleeved radially outside the cylindrical output shaft. A plurality of first clutch members are distributed between the cylindrical output shaft and the inner sleeve, and a plurality of second clutch members are distributed between the cylindrical output shaft and the outer sleeve; the first clutch members and the second clutch members are arranged in the opposite direction;

[0016] The bearings include a first bearing and a second bearing. The first bearing is assembled between the inner sleeve and the first cylindrical rotor shaft and is adjacent to the torque transmission structure. The second bearing is assembled between the cylindrical output shaft and the first cylindrical rotor shaft and is away from the torque transmission structure. Accordingly, the first cylindrical rotor shaft is supported by bearings at two axial positions, ensuring its assembly accuracy.

[0017] Preferably, the specification of the first bearing is larger than that of the second bearing. Accordingly, at the position adjacent to the torque transmission structure, the first cylindrical rotor shaft is radially supported by the first bearing with a larger specification, ensuring the reliable transmission and accuracy of the torque transmission structure.

[0018] Preferably, a third bearing is assembled between the radially inner side of the cylindrical output shaft and the torque assembly, and a fourth bearing is assembled between the radially outer side of the cylindrical output shaft and the housing. The third bearing and the fourth bearing are radially corresponding. Accordingly, the cylindrical output shaft is supported and positioned by the third bearing and the fourth bearing on the inner and outer sides at the same time, ensuring its flexible operation and avoiding shaking.

[0019] Preferably, a fifth bearing is assembled between the radially inner side of one end of the modulation ring and the first cylindrical rotor shaft, and a sixth bearing is assembled between the radially inner side of the other end of the modulation ring and the housing. Accordingly, the cooperation relationship between the modulation ring and the first rotor is ensured. It is ensured that the first rotor will not be eccentric in concentricity due to the magnetic saturation difference of the first rotor magnet ring.

[0020] Preferably, the fifth bearing is a ceramic bearing. It is used to avoid being affected by the magnetic field of the first rotor.

[0021] Preferably, a seventh bearing is assembled between the radially inner side of one end of the second cylindrical rotor shaft and the torque assembly, and an eighth bearing is assembled between the radially outer side of the other end of the second cylindrical rotor shaft and the housing. Accordingly, the second cylindrical rotor shaft is supported by bearings at two axial positions, ensuring its assembly accuracy. Especially, it is ensured that the second rotor will not be eccentric in concentricity due to the magnetic saturation difference of the rotor magnet ring.

[0022] Preferably, the eighth bearing is a ceramic bearing to avoid being affected by the magnetic field of the second rotor.

[0023] Preferably, a ninth bearing is assembled between the radial outer side of the end of the torque assembly away from the two-way clutch and the housing to provide positioning and support for the torque assembly.

[0024] Preferably, the housing includes a first housing and a second housing, and the first housing and the second housing are axially butted on the radial outer side of the torque transmission structure. This is conducive to reducing the probability of eccentricity when assembling the first rotor and the modulation ring on the first housing and the second rotor on the second housing, and is conducive to docking the assembled first rotor, modulation ring and first housing with the assembled second rotor and second housing to complete the assembly of the whole machine and ensure the assembly accuracy. Description of the Drawings

[0025] Figure 1 is a schematic cross-sectional structure diagram of the magnetic drive reduction mid-mounted motor for a power-assisted bicycle of the present invention;

[0026] Figure 2 is an exploded schematic diagram of the structures of the first rotor and the second rotor of the present invention;

[0027] Figure 3 is a schematic diagram of the first rotor and the second rotor of the present invention assembled together;

[0028] Figure 4 is Figure 3 a sectional view taken along the line K-K of

[0029] Explanation of the reference numerals in the drawings:

[0030] 100 Housing: 101 First housing, 102 Second housing, 103 Inner housing, 104 Shielding ring;

[0031] 200 Torque assembly: 201 Motor shaft, 202 Torque sleeve,

[0032] 300 Motor part: 310 Second stator; 320 Second rotor, 321 Second cylindrical rotor shaft, 3211 External spline, 322 Second rotor magnetic pole assembly;

[0033] 400 Magnetic drive reduction device: 410 First stator; 420 First rotor, 421 First cylindrical rotor shaft, 4211 Internal spline, 422 First rotor magnetic pole assembly; 430 Modulation ring;

[0034] 500 Two-way clutch: 501 Cylindrical output shaft, 502 Inner sleeve, 503 Outer sleeve, 504 First clutch member, 505 Second clutch member;

[0035] 601 Sensor, 602 Controller;

[0036] 701 First bearing, 702 Second bearing, 703 Third bearing, 704 Fourth bearing, 705 Fifth bearing, 706 Sixth bearing, 707 Seventh bearing, 708 Eighth bearing, 709 Ninth bearing. Detailed implementation mode

[0037] To make the objectives, technical solutions and advantages of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments in the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0038] The terms "including" and "having" and any variations thereof in the description and claims of the present utility model are intended to cover non-exclusive inclusion. For example, a method or product including a series of technical features does not necessarily limit to those clearly listed technical features, but may also include other technical features that can be included in the method or product and are not clearly listed.

[0039] In the description of the present utility model, it should be understood that the technical features defined by the terms "first", "second", "third", etc. with sequential concepts are only for clearly describing the defined technical features, so that the defined technical features can be clearly distinguished from other technical features, rather than being named in actual implementation. Therefore, it should not be construed as a limitation to the present utility model.

[0040] The present utility model will be introduced in detail below in conjunction with specific embodiments and the accompanying drawings.

[0041] The assisted bicycle is well-known. It drives the bicycle forward by the rider pedaling the pedals to transmit torque to the wheels. Configuring a mid-drive motor for the bicycle provides external power without affecting pedal cycling, making it easier for the rider. Compared with the hub motor, since the hub motor co-axially configures the motor and the wheel to directly transmit power to the wheel, the hub motor will generate resistance to the vehicle when the vehicle slides forward. While the mid-drive motor is installed in the middle of the frame and transmits power to the wheel through a transmission mechanism, so that the bicycle is basically not affected by the resistance of the mid-drive motor when sliding forward, enabling the bicycle to slide a longer distance.

[0042] The present utility model provides such a magnetic drive reduction mid-drive motor for an assisted bicycle.

[0043] Such as Figure 1Shown is the magnetic drive reduction mid-motor for a power-assisted bicycle according to this embodiment, which includes: a housing 100, a torque assembly 200, a motor part 300, a magnetic drive reduction device 400, a two-way clutch 500, a sensor 601, a controller 602, and several bearings.

[0044] The housing 100 serves as the assembly base for the torque assembly, the motor part, the magnetic drive reduction device, and the two-way clutch, and is also used to assemble the mid-motor on the bicycle. In Figure 1 In the shown structure, the housing 100 includes a first housing 101 and a second housing 102. The first housing 101 and the second housing 102 are axially butted on the radial outside of the torque transmission structure and assembled together by fasteners. Since the housing is divided into two sections by the first housing and the second housing instead of more sections, the number of assembly connection positions is reduced, and the assembly accuracy of the rotatable structure inside can be guaranteed. And, since the first housing and the second housing are axially butted on the radial outside of the torque transmission structure, it is convenient for the overall machine assembly.

[0045] The torque assembly 200 penetrates through the housing 100 and its two ends extend out of the housing to receive an external torque, such as the torque generated by pedaling during riding. In Figure 1 In the shown structure, the torque assembly 200 includes a motor shaft 201 and a torque sleeve 202. The torque sleeve 202 is sleeved on the motor shaft and assembled with the motor shaft by splines so that the torque sleeve rotates with the motor shaft. A fixed inner housing 103 is arranged outside the torque assembly. One end of the inner housing 103 is fixed to the second housing 102 of the housing 100, so that the torque assembly 200 can rotate relative to the housing 100.

[0046] The motor part 300 is Figure 1 enclosed by a double-dot dash line in the figure. The motor part 300 includes a second stator 310 and a second rotor 320.

[0047] The second stator 310 includes a second stator core attached to the second housing 102 of the housing and a second winding wound around the second stator core. By applying an alternating signal to the second winding, a changing magnetic field can be generated to drive the second rotor to rotate. The second rotor 320 is located inside the second stator 310 and is arranged coaxially with the second stator.

[0048] As Figures 2 - 4 shown, the second rotor 320 includes a second cylindrical rotor shaft 321 and a second rotor magnetic pole assembly 322 attached to the second cylindrical rotor shaft. The second rotor magnetic pole assembly 322 is used to provide a second rotor magnetic field that rotates with the second rotor.

[0049] The magnetic drive reduction device 400 includes a first stator 410, a first rotor 420, and a modulation ring 430.

[0050] The first stator 410 is fixed within the first housing 101 of the machine housing. A steel ring is embedded in the inner wall of the first housing 101 and serves as a shielding ring 104 to shield the magnetic field of the first stator. The first stator 410 includes an annular first stator pole assembly, and the first stator pole assembly is used to provide a fixed first stator magnetic field.

[0051] The first rotor 420 includes a first cylindrical rotor shaft 421 and a first rotor pole assembly 422 attached to the first cylindrical rotor shaft; the first rotor pole assembly 422 is used to provide a first rotor magnetic field that rotates with the first rotor. The first rotor 420 is located inside the first stator 410 and is arranged coaxially with the first stator.

[0052] In the illustrated structure, the first rotor 420 and the second rotor 320 are separately configured and coaxially assembled together through a torque transmission structure so that the first rotor is driven by the second rotor to rotate synchronously. In particular, the torque transmission structure is a spline transmission structure. The spline transmission structure includes an internal spline 4211 provided on the first cylindrical rotor shaft 421 and an external spline 3211 provided on the second cylindrical rotor shaft 321. The external spline 3211 extends into the internal spline 4211 to achieve a transmission fit.

[0053] The modulation ring 430 is located radially between the first rotor 420 and the first stator 410. The modulation ring 430 is arranged coaxially with the first rotor 420 and the first stator 410. A first air gap is maintained between the modulation ring 430 and the first stator 410, and a second air gap is maintained between the modulation ring 430 and the first rotor 420.

[0054] The two-way clutch 500 is disposed between the torque assembly 200 and the modulation ring 430 and is used to selectively transmit torque to or from the modulation ring by the torque assembly. The two-way clutch 500 has a cylindrical output shaft 501 that extends out of the machine housing for outputting torque, and the cylindrical output shaft 501 is sleeved on the radial outer side of one end of the torque assembly 200.

[0055] The bi-directional clutch 500 further includes an inner sleeve 502, an outer sleeve 503, a plurality of first clutch members 504 and a plurality of second clutch members 505. The inner sleeve 502 is configured on the torque assembly 200 through spline fit and rotates together with the torque assembly. The outer sleeve 503 is fixedly configured on the modulation ring by being die-cast together with one end face of the modulation ring and rotates together with the modulation ring. The cylindrical output shaft 501 is sleeved on the radial outer side of the inner sleeve 502. The outer sleeve 503 is sleeved on the radial outer side of the cylindrical output shaft 501. A plurality of first clutch members 504 are distributed between the cylindrical output shaft 501 and the inner sleeve 502. A plurality of second clutch members 505 are distributed between the cylindrical output shaft 501 and the outer sleeve 503. The first clutch members 504 and the second clutch members 505 are arranged in opposite directions. For example, if the first clutch members and the second clutch members have the same cross-sectional structure, the opposite arrangement of the first clutch members and the second clutch members is reflected in their opposite installation directions, so that the first clutch members and the second clutch members can only transmit torque in one direction and the directions of torque transmission of the two are opposite.

[0056] In Figure 1 this case, the first clutch members 504 and the second clutch members 505 are located at different axial positions, and the first clutch members and the second clutch members are axially misaligned. In other embodiments, the first clutch members 504 and the second clutch members 505 may be located at the same axial position and correspond to each other radially.

[0057] As Figure 1 shown, the first cylindrical rotor shaft 421 is sleeved on the radial outer side of the bi-directional clutch 500, and a first bearing 701 and a second bearing 702 are assembled between the two to maintain their rotational fit. The first bearing 701 is assembled between the inner sleeve 502 and the first cylindrical rotor shaft 421 and is adjacent to the torque transmission structure, and the second bearing 702 is assembled between the cylindrical output shaft 501 and the first cylindrical rotor shaft 421 and is far from the torque transmission structure. Accordingly, the first cylindrical rotor shaft 421 is supported by bearings at two axial positions, ensuring its assembly accuracy.

[0058] The specification of the first bearing 701 is larger than that of the second bearing 702. Accordingly, at the position adjacent to the torque transmission structure, the first cylindrical rotor shaft is radially supported by the larger-specification first bearing, ensuring the reliable transmission and accuracy of the torque transmission structure.

[0059] A third bearing 703 is assembled between the radial inner side of the cylindrical output shaft 501 and the torque assembly 200, and a fourth bearing 704 is assembled between the radial outer side of the cylindrical output shaft 501 and the first housing 101 of the machine housing. The third bearing 703 and the fourth bearing 704 correspond to each other radially. Accordingly, the cylindrical output shaft 501 is supported and positioned by the third bearing and the fourth bearing on the inner and outer sides at the same time, ensuring that it can rotate flexibly and avoiding shaking.

[0060] A fifth bearing 705 is assembled between the radial inner side of one end of the modulation ring 430 and the first cylindrical rotor shaft 421, and a sixth bearing 706 is assembled between the radial inner side of the other end of the modulation ring 430 and the first housing 101 of the machine housing. Accordingly, the mating relationship between the modulation ring 430 and the first rotor 420 is ensured. It is ensured that the first rotor will not be eccentric in concentricity due to the magnetic saturation difference of the first rotor magnetic ring. The fifth bearing 705 is a ceramic bearing to avoid being affected by the magnetic field of the first rotor.

[0061] A seventh bearing 707 is assembled between the radial inner side of one end of the second cylindrical rotor shaft 321 and the torque assembly 200, and an eighth bearing 708 is assembled between the radial outer side of the other end of the second cylindrical rotor shaft 321 and the second housing 102 of the machine housing. Accordingly, the second cylindrical rotor shaft 321 is supported by bearings at two positions in the axial direction, ensuring its assembly accuracy. In particular, it is ensured that the second rotor 320 will not be eccentric in concentricity due to the magnetic saturation difference of the rotor magnetic ring. The eighth bearing 708 is a ceramic bearing to avoid being affected by the magnetic field of the second rotor.

[0062] A ninth bearing 709 is assembled between the radial outer side of the end of the torque assembly 200 far from the two-way clutch 500 and the first housing 101 of the machine housing 100. It is used to provide positioning and support for the torque assembly.

[0063] In view of the positioning and support of the foregoing bearings, the torque assembly 200, the first rotor 420, the second rotor 320, and the modulation ring 430 can all rotate relative to the machine housing 100, and the cylindrical output shaft 501 of the two-way clutch 500 can rotate relative to the torque assembly 200 and the modulation ring 430.

[0064] In view of the split structure of the foregoing first rotor and second rotor and the arrangement positions of the bearings, when assembling the inboard motor, the motor part 300 and the magnetic drive reduction device 400 can be respectively assembled with the torque assembly 200 first, and then the motor part 300 and the magnetic drive reduction device 400 can be docked along the torque assembly 200, reducing the influence of the magnetic field on the first rotor, the second rotor, and the modulation ring. The assembly difficulty is reduced, and the assembly accuracy of the product and the consistency of the mass product assembly are ensured.

[0065] When the pedaling motion during cycling causes the torque assembly to rotate in the direction of driving the vehicle forward, the torque assembly 200 causes the inner sleeve 502 to rotate synchronously in the same direction. The first clutch member 504 has a tendency to rotate in the first direction (such as counterclockwise) due to friction. The first clutch member is pressed between the cylindrical output shaft 501 and the inner sleeve 502. The rotation of the inner sleeve 502 is transmitted in the same direction to the cylindrical output shaft 501 by the first clutch member, causing the cylindrical output shaft 501 to rotate in the same direction as the torque assembly 200 and the inner sleeve 502. Through the transmission mechanism connected between the cylindrical output shaft 501 and the drive wheel, the drive wheel is driven to rotate, promoting the bicycle to move forward. When the cylindrical output shaft 501 rotates in the same direction as the torque assembly 200 and the inner sleeve 502, the second clutch member 505 also has a tendency to rotate in the first direction due to friction. However, since the second clutch member 505 is arranged in the opposite direction to the first clutch member 504, the second clutch member 505 does not transmit the rotation of the cylindrical output shaft to the outer sleeve 503. At this time, the torque applied to the torque assembly by pedaling is not transmitted to the outer sleeve and the modulation ring. This situation is suitable for driving the bicycle forward by pedaling.

[0066] By supplying power to the mid-drive motor to start the mid-drive motor, the second rotor 320 rotates by the magnetic flux generated by the second stator 310. The first rotor 420 is driven to rotate synchronously by the second rotor 320, and the power of the motor part 300 is transmitted to the modulation ring 430 of the magnetic drive reduction device 400. The modulation ring 430 drives the outer sleeve 503 to rotate in the direction of driving the vehicle forward. When the outer sleeve 503 rotates in the direction of driving the vehicle forward, the second clutch member 505 has a tendency to rotate in the first direction (such as clockwise) due to friction. The second clutch member 505 is pressed between the cylindrical output shaft 501 and the outer sleeve 503. The rotation of the outer sleeve 503 is transmitted in the same direction to the cylindrical output shaft 501 by the second clutch member 505, causing the cylindrical output shaft 501 to rotate synchronously in the same direction as the outer sleeve 503. Through the transmission mechanism connected between the cylindrical output shaft 501 and the drive wheel, the drive wheel is driven to rotate, promoting the bicycle to move forward. When the cylindrical output shaft 501 rotates synchronously in the same direction as the outer sleeve 503, the first clutch member 504 has a tendency to rotate in the first direction (such as clockwise) due to friction. The first clutch member 504 does not transmit the rotation of the cylindrical output shaft in the same direction to the inner sleeve 502. At this time, the torque of the modulation ring is not transmitted to the torque assembly. This situation is suitable for driving the bicycle forward by the mid-drive motor.

[0067] During the process of cycling, when the bicycle slides forward, through the one-way clutch mechanism of the transmission mechanism between the mid-drive motor and the drive wheel, such as the ratchet and pawl mechanism arranged in the drive wheel and the driven sprocket, the power transmission between the driving sprocket and the driven sprocket of the mid-drive motor is cut off, and no pedaling power or motor power needs to be provided to the bicycle.

[0068] During the process of riding a bicycle, when performing actions such as turning around that cause the wheels of the bicycle to rotate backward, a transmission is established between the bicycle drive wheel and the cylindrical output shaft 501 through a transmission mechanism. According to the rotation of the cylindrical output shaft when the bicycle is moving forward as described above, the backward rotation of the bicycle drive wheel causes the rotation of the cylindrical output shaft 501 to be in the opposite direction to that when driving the bicycle forward. The rotation of the cylindrical output shaft 501 causes the inner sleeve 502 and the torque assembly 200 to rotate synchronously and in the same direction through the first clutch member 504, and causes the outer sleeve and the modulation ring to rotate synchronously and in the same direction through the second clutch member 505. At this time, power is not supplied to the mid-mounted motor, and the mid-mounted motor is in a non-operating state.

[0069] During the riding process, driving the bicycle forward through pedaling and driving the bicycle forward through the mid-mounted motor may be alternated. For this reason, the mid-mounted reduction motor includes a sensor 601 and a controller 602. The controller controls the motor part to work according to the signal of the torque assembly receiving the pedaling driving torque provided by the sensor. Accordingly, when the mid-mounted reduction motor is installed on the bicycle, the motor part is instructed to work through pedaling to drive the assisted bicycle forward. Among them, the sensor 601 is arranged on the inner shell 103 to detect the torque assembly receiving the pedaling driving torque. The pedaling driving torque can be a pressure signal or the rotation of the torque assembly. And the controller 602 is arranged in the control box of the mid-mounted motor or arranged on the vehicle in other embodiments. When the rider wants to ride the bicycle forward, the rider pedals the pedal, and transmits the pedaling driving torque generated by the pedaling action to the torque assembly 200 through the crank. The sensor 601 detects the rotation trend of the torque assembly 200 or the pressure signal or rotation signal generated by the rotation and provides the signal to the controller, and the controller controls the mid-mounted motor to work.

Claims

1. A magnetic transmission reduction mid-mounted motor for a power-assisted bicycle, comprising: Housing (100); A torque assembly (200) which penetrates the housing (100) and has two ends extending out of the housing to receive external torque; A magnetic transmission speed reducer (400) comprising a first stator (410), a first rotor (420) and a modulation ring (430); A motor part (300) including a second stator (310) and a second rotor (320); A two-way clutch (500) is arranged between the torque assembly (200) and the modulation ring (430) for selectively transmitting torque to it by the torque assembly or by the modulation ring, the two-way clutch having a cylindrical output shaft (501) extending out of the housing for outputting torque, the cylindrical output shaft (501) being sleeved on the radially outer side of one end of the torque assembly (200); The invention is characterized in that the first rotor (420) and the second rotor (320) are configured separately and are coaxially assembled together through a torque transmission structure so that the second rotor drives the first rotor to rotate synchronously.

2. The mid-mounted motor according to claim 1 is characterized in that: The torque transmission structure is a spline transmission structure.

3. The mid-mounted motor according to claim 1 or 2, characterized in that: The first rotor (420) comprises a first cylindrical rotor shaft (421) and a first rotor pole assembly (422) attached to the first cylindrical rotor shaft; the second rotor (320) comprises a second cylindrical rotor shaft (321) and a second rotor pole assembly (322) attached to the second cylindrical rotor shaft; the first cylindrical rotor shaft (421) and the second cylindrical rotor shaft (321) are coaxially assembled via a torque transmission structure.

4. The mid-mounted motor according to claim 3 is characterized in that: The first cylindrical rotor shaft (421) is sleeved on the radially outer side of the two-way clutch (500), and a bearing is installed between the two to maintain the rotational fit between the two.

5. The mid-mounted motor according to claim 4 is characterized in that: The bidirectional clutch (500) comprises an inner sleeve (502), an outer sleeve (503), a plurality of first clutch members (504) and a plurality of second clutch members (505); the inner sleeve (502) is arranged on the torque assembly (200) and rotates together with the torque assembly; the outer sleeve (503) is arranged on the modulation ring (430) and rotates together with the modulation ring; the cylindrical output shaft (501) is sleeved on the radial outer side of the inner sleeve (502); the outer sleeve (503) is sleeved on the radial outer side of the cylindrical output shaft (501); the plurality of first clutch members (504) are distributed between the cylindrical output shaft (501) and the inner sleeve (502); and the plurality of second clutch members (505) are distributed between the cylindrical output shaft (501) and the outer sleeve (503); the first clutch member (504) and the second clutch member (505) are arranged in opposite directions; The bearing comprises a first bearing (701) and a second bearing (702), wherein the first bearing (701) is assembled between the inner sleeve (502) and the first cylindrical rotor shaft (421) and is adjacent to the torque transmission structure, and the second bearing (702) is assembled between the cylindrical output shaft (501) and the first cylindrical rotor shaft (421) and is away from the torque transmission structure.

6. The mid-mounted motor according to claim 5 is characterized in that: The specification of the first bearing (701) is greater than that of the second bearing (702).

7. The mid-mounted motor according to claim 5 is characterized in that: A third bearing (703) is mounted between the radial inner side of the cylindrical output shaft (501) and the torque assembly (200), and a fourth bearing (704) is mounted between the radial outer side of the cylindrical output shaft (501) and the housing (100). The third bearing (703) and the fourth bearing (704) correspond to each other in radial direction.

8. The mid-mounted motor according to claim 3 is characterized in that: A fifth bearing (705) is mounted between the radial inner side of one end of the modulation ring (430) and the first cylindrical rotor shaft (421), and a sixth bearing (706) is mounted between the radial inner side of the other end of the modulation ring (430) and the housing (100).

9. The mid-mounted motor according to claim 8, characterized in that: The fifth bearing (705) is a ceramic bearing.

10. The mid-mounted motor according to claim 3 is characterized in that: A seventh bearing (707) is mounted between the radial inner side of one end of the second cylindrical rotor shaft (321) and the torque assembly (200), and an eighth bearing (708) is mounted between the radial outer side of the other end of the second cylindrical rotor shaft (321) and the housing (100).

11. The mid-mounted motor according to claim 10, characterized in that: The eighth bearing (708) is a ceramic bearing.

12. The mid-mounted motor according to claim 10, characterized in that: A ninth bearing (709) is installed between the radial outer side of one end of the torque assembly (200) away from the two-way clutch (500) and the housing (100).

13. The mid-mounted motor according to claim 1 or 2, characterized in that: The casing (100) comprises a first shell (101) and a second shell (102), wherein the first shell (101) and the second shell (102) are axially butted against each other at the radial outer side of the torque transmission structure.

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