Magnetic transmission speed-reduction apparatus and mid-drive electric motor for power-assisted bicycle

Abstract

The present invention belongs to the power-assisted techniques of bicycles. Disclosed are a magnetic transmission speed-reduction apparatus and a mid-drive electric motor for a power-assisted bicycle. The existing mid-drive electric motors have a large size, low rotation efficiency and high operating noise. In the present invention, a modulation ring is placed between a first rotor and a first stator, and power is transmitted by means of a magnetic-field coupling effect; a first air gap is formed between the modulation ring and the first stator, and a second air gap is formed between the modulation ring and the first rotor; during operation, an electric motor drives the first rotor to rotate, and magnetic fields generated by the first rotor and the first stator are each modulated by the modulation ring to generate a series of spatial harmonic magnetic fields at the first air gap and the second air gap; and by means of magnetic-field coupling, stable output torques are generated on the modulation ring, thereby achieving the effects of speed reduction and torque amplification. Due to the friction-free characteristic of magnetic transmission and the ultra-high torque density brought about by the magnetic flux concentration structure and high-magnetic-permeability material of the present invention, the system efficiency is improved, and the operating noise is reduced.

Description

Magnetic transmission deceleration device and mid-mounted motor of power-assisted bicycle TECHNICAL FIELD

[0001] The present application belongs to the power-assisted bicycle mid-mounted motor power-assisted technology, and particularly relates to a magnetic transmission deceleration device and a mid-mounted motor of a power-assisted bicycle. BACKGROUND

[0002] The mid-mounted motor of a power-assisted bicycle or a bicycle is usually output by a motor through a deceleration device, wherein the deceleration device is a gear deceleration device, a cycloid needle deceleration device or a harmonic deceleration device, so that the mid-mounted motor is large in size, low in rotation efficiency, loud in noise during operation and short in service life.

[0003] SUMMARY

[0004] The present application aims to overcome at least one of the defects of the prior art, such as large size, low rotation efficiency, loud noise during operation and short service life, and to provide a magnetic transmission deceleration device and a mid-mounted motor of a power-assisted bicycle.

[0005] To achieve the above-mentioned purpose, the magnetic transmission deceleration device of the present application comprises a first stator, a first rotor and a modulation ring, wherein:

[0006] The first stator comprises a first stator magnetic pole assembly for providing a constant first stator magnetic field;

[0007] The first rotor comprises a first rotor permanent magnet, and the first rotor magnetic pole assembly is used for providing a first rotor magnetic field rotating with the first rotor, and the first rotor is located inside the first stator and coaxial with the first stator;

[0008] The modulation ring is located between the first rotor and the first stator, and is coaxial with the first rotor and the first stator, and a first air gap is maintained between the modulation ring and the first stator, and a second air gap is maintained between the modulation ring and the first rotor;

[0009] The first stator and the first rotor are configured to have different pole pairs, so that the magnetic field of the first air gap and the magnetic field of the second air gap are coupled, and the rotation from the first rotor is decelerated and output by the modulation ring.

[0010] The present application realizes deceleration through magnetic transmission, improves the maximum output torque under the premise of limited installation space of the mid-mounted motor, and further improves the motor operation efficiency and reduces the overall noise of the motor.

[0011] Preferably, the magnetic field of the first stator is inwardly magnetized, and the magnetic field of the first rotor is outwardly magnetized. In particular, the magnetic field of the first stator magnetic pole assembly and the magnetic field of the first rotor magnetic pole assembly are both in a Halbach Array structure. The field strength of the space where the modulation ring part is located is greatly improved.

[0012] Preferably, the first rotor magnetic pole assembly is assembled by magnetizing the first rotor permanent magnet blocks, and each single pole is divided into four blocks, and the whole is outwardly magnetized; the first stator magnetic pole assembly is assembled by magnetizing the first stator permanent magnet blocks, and each single pole is divided into two blocks, which are radial magnetization and tangential magnetization, respectively, and the whole is inwardly magnetized. Accordingly, a stronger magnetic field is provided to achieve larger torque transmission

[0013] Preferably, the first rotor has p1 pole pairs, and the first rotor includes 8×p1 first rotor permanent magnet blocks, and the magnetization direction of adjacent two first rotor permanent magnet blocks is different by (45-360 / (8×p1)) degrees. The utilization rate of magnetic force is maximized, and the process is easy to implement.

[0014] Preferably, the axial projection profile of the first rotor permanent magnet is a sector, the size of each first rotor permanent magnet is the same, the radial thickness of each first rotor permanent magnet is H1, the circumferential average width of each first rotor permanent magnet is W1, and H1 / W1=0.8-1.5. The utilization rate of magnetic force is maximized while ensuring the feasibility of the process.

[0015] Preferably, the first stator permanent magnet is arranged in any of the following ways:

[0016] (1) The axial projection profile of each first stator permanent magnet is a sector and the size is the same, the first stator permanent magnet is divided into radial permanent magnets and tangential permanent magnets, the radial permanent magnets are radially magnetized, the tangential permanent magnets are tangentially magnetized, the radial permanent magnets and the tangential permanent magnets are spliced into the first stator magnetic pole assembly, the magnetization directions of adjacent two radial permanent magnets are opposite, and the magnetization directions of adjacent two tangential permanent magnets are opposite; the radial thickness of the first stator permanent magnet is H3, the circumferential average width of the first stator permanent magnet is W3, and W3 / H3=0.52-0.6; the magnetic circuit is optimized and the output torque is maximized.

[0017] (2) The axial projection profile of each first stator permanent magnet is a sector, the first stator permanent magnet is divided into large-size permanent magnets and small-size permanent magnets, the large-size permanent magnets are radially magnetized, the small-size permanent magnets are tangentially magnetized, the large-size permanent magnets and the small-size permanent magnets are spliced into the first stator magnetic pole assembly in an interval, the magnetization directions of the adjacent two large-size permanent magnets are opposite, the magnetization directions of the adjacent two small-size permanent magnets are opposite, the included angle of the two radial edges of the small-size permanent magnet is D2, the radial thickness of the small-size permanent magnet is H5, the included angle of the two radial edges of the large-size permanent magnet is D3, the radial thickness of the large-size permanent magnet is H6, and 1.5 < D3 / D2 < 2.2 and 0.4 < H6 / H5 < 0.6. The output torque is maximized while the amount of magnetic steel is reduced.

[0018] (3) The axial projection profile of each first stator permanent magnet is a triangle, the first stator permanent magnet is divided into corner-centric permanent magnets and edge-centric permanent magnets, the edge-centric permanent magnets are radially magnetized, the corner-centric permanent magnets are tangentially magnetized, the corner-centric permanent magnets and the edge-centric permanent magnets are spliced into the first stator magnetic pole assembly in an interval, the magnetization directions of the adjacent two corner-centric permanent magnets are opposite, the magnetization directions of the adjacent two edge-centric permanent magnets are opposite, the edges of the corner-centric permanent magnets form the outer edges of the first stator magnetic pole assembly, the edges of the edge-centric permanent magnets form the inner edges of the first stator magnetic pole assembly, the adjacent edges of the corner-centric permanent magnets and the edge-centric permanent magnets are equal in length and completely aligned, the outer diameter of the first stator is d5, the inner diameter of the first stator is d4, the number of pole pairs of the first stator is p3, and 0.8 x d4 x sin(360deg / 4p3) < d5-d4 < 0.9 x d4 x sin(360deg / 4p3). At this time, the magnetic circuit is optimal, the cohesion magnetic effect is best, and the torque density is highest.

[0019] Preferably, the modulation ring comprises modulation teeth, the modulation teeth are made of high-saturation magnetic induction material. Thus, the maximum output torque (i.e. torque density) of the speed reducer is greatly improved under the condition that the installation space size is fixed, torque is transmitted through the magnetic field, and there is no friction. There is no mechanical loss, and the motor operating efficiency is improved, and the overall noise of the motor is reduced.

[0020] Preferably, the modulation ring comprises a squirrel cage, the squirrel cage comprises two end plates and a plurality of connecting rods connected between the two end plates, the connecting rods extend axially and are distributed along the circumference, and the modulation teeth are fixed in the gap between the adjacent connecting rods. In this way, the overall strength of the modulation ring is ensured.

[0021] Preferably, each modulation tooth is uniform in size, the total number of modulation teeth is p2, the axial projection profile of the modulation tooth is a sector, the included angle of the two radial edges of the modulation tooth is D1, and D1 / (360deg / p2) = 0.5-0.6; the radial thickness of the modulation tooth is H2, the circumferential average width of the modulation tooth is W2, and H2 / W2 = 0.55-1.3. The modulation effect is best.

[0022] Preferably, the connecting rod is cylindrical, and the circular arc groove is arranged at the middle position of the circumferential two sides of the modulating tooth, and the circular arc groove is attached to the surface of the connecting rod to support the connecting rod and the cylindrical shape with each other. The modulating effect is not affected, and the overall structural strength after the installation of the modulating ring is increased.

[0023] Preferably, the first rotor pole pair number is p1, the total number of modulating teeth is p2, the first stator pole pair number is p3, and p1=|p2-p3|.

[0024] Preferably, the first stator is fixed to the shell, and the inner wall of the shell is embedded with a shielding ring to reduce the magnetic leakage to the outside of the shell. The first rotor has too strong magnetic gathering ability, which can generate a large eddy current loss in the shell. When the shielding ring is embedded in the inner wall of the shell, the thickness of the shell can be reduced, which ensures the overall strength of the shell and makes the shielding ring shield the magnetic field, thereby effectively reducing the eddy current of the shell.

[0025] Preferably, the thickness H4 of the shielding ring, the outer diameter d1 of the first rotor, the inner diameter d5 of the shielding ring, and the first rotor pole pair number p1 satisfy the following formula relationship:

[0026] d5-d1<d1×sin(360deg / 4p1), H4≥0.185×d1×(1+sin(360deg / 4p1))-0.5×d5. According to the above, the shielding ring can effectively shield the magnetic field to reduce the eddy current loss.

[0027] If d5-d1>d1×sin(360deg / 4p1), the shielding ring can not be needed.

[0028] Preferably, the shielding ring is axially divided into N segments, the axial length of each shielding ring is L1, the axial length of the first stator magnetic pole assembly is L, all the shielding rings are uniformly distributed along the axis, the shielding ring located at the end is aligned with the first stator magnetic pole assembly, the distance between the end faces of the two shielding rings close to each other is (L-N*L1) / (N-1), and L1>0.65*(L / N), N<10. According to the above, the weight of the shielding ring can be further reduced, and the torque loss caused by the magnetic shielding effect can be reduced to a certain extent.

[0029] In order to achieve the above purpose, the bicycle middle reduction motor of the application is characterized by comprising:

[0030] a shell;

[0031] a torque component which penetrates the shell and extends out of the shell at both ends to receive external torque (such as the torque generated by the pedals when riding);

[0032] The motor part comprises a second stator and a second rotor, the second stator comprises a core and a winding wound on the core, the winding generates a rotating magnetic field when electrified, and the second rotor comprises a second rotor, the second rotor is used for providing a permanent magnetic field matched with the electromagnetic field generated by the winding of the stator, the second rotor is located inside the second stator and coaxial with the second stator, and a third air gap is kept between the second rotor and the second stator;

[0033] The first rotor is synchronously rotated by the second rotor in the magnetic force transmission reduction device;

[0034] The bidirectional clutch is arranged between the torque assembly and the modulation ring and is used for selectively transmitting torque from the torque assembly or the magnetic force transmission reduction device to the modulation ring, the bidirectional clutch has a cylindrical output shaft extending out of the casing and used for outputting torque, and the cylindrical output shaft is sleeved on the radially outer side of one end of the torque assembly.

[0035] The power of the motor part is transmitted to the reduction device by the second rotor synchronously rotating the first rotor, and is output by the modulation ring. The motor part and the magnetic force transmission reduction device are both driven by magnetic force, the field strength of the space where the modulation ring is located is greatly improved, the maximum output torque (i.e. torque density) of the reduction device in the case of fixed installation space is greatly improved, and the operation efficiency of the motor is improved, and the overall noise of the motor is reduced.

[0036] Preferably, the middle reduction motor comprises a sensor and a controller, the controller instructs the motor part to work according to the torque signal provided by the sensor. Accordingly, when the middle reduction motor is installed on the bicycle, the motor part is instructed to work to drive the power assistance by the pedaling action, and the bicycle advances.

[0037] Preferably, a fixed inner casing is arranged on the outside of the torque assembly, and the sensor is arranged in the inner casing to detect the torque signal and receive the pedaling driving torque. Specifically, the pedaling driving torque can be a pressure signal or the rotating speed of the torque assembly.

[0038] Preferably, the bidirectional clutch comprises an inner sleeve, an outer sleeve, a plurality of first clutch members and a plurality of second clutch members, the inner sleeve is arranged on the torque assembly and rotates with the torque assembly, the outer sleeve is arranged on the modulation ring and rotates with the modulation ring, the tubular output shaft is sleeved on the radial outer side of the inner sleeve, the outer sleeve is sleeved on the radial outer side of the tubular output shaft, the plurality of first clutch members are distributed between the tubular output shaft and the inner sleeve, and the plurality of second clutch members are distributed between the tubular output shaft and the outer sleeve; the first clutch members and the second clutch members are reversely arranged. Accordingly, the first outer circumferential surface and the first inner circumferential surface can only work selectively through the torque transmission of the first clutch members and the torque transmission of the second clutch members, and one of the first clutch members and the second clutch members transmits torque while the other does not transmit torque. The center-mounted reduction motor is suitable for various moving forms of the bicycle: first, when the bicycle is normally started from a stationary state, the pedal action is allowed to drive the bicycle to move without being hindered by the center-mounted reduction motor, at this time, the center-mounted reduction motor is not powered and does not work; second, by powering the center-mounted reduction motor, the center-mounted reduction motor is allowed to drive the bicycle to move without being hindered by the torque assembly, at this time, the pedal action can be stopped. Third, when the sensor detects the pedal action, an electrical signal is provided to the controller, the controller can realize different sizes of rotating torque by controlling the size of the winding current to drive the second rotor, the motor and the pedal force provide power at the same time, at this time, the torque size provided by the motor is determined by the pedal force and the pedal frequency,

[0039] In order to facilitate assembly with other parts, the torque assembly comprises a motor shaft and a torque sleeve sleeved on the motor shaft and rotating with the motor shaft. In this way, the machining of the torque assembly can be simplified, and different materials can be selected for the motor shaft and the torque sleeve according to structural requirements. Accordingly, it is easy to think that, in the case that the machining process can be realized, the torque assembly can be embodied as one component.

[0040] Preferably, the second rotor comprises a second rotor core, a main magnetic steel and an auxiliary magnetic steel arranged at intervals on the circumference of the second rotor core, the main magnetic steel is tangentially magnetized, the auxiliary magnetic steel is radially magnetized, and the second rotor core has an interval magnetic bridge between the main magnetic steel and the auxiliary magnetic steel for isolating the main magnetic steel and the auxiliary magnetic steel. The interval magnetic bridge can achieve the effect of concentrating magnetic field to the air gap, effectively improve the output torque, and at the same time, can save the amount of magnetic steel more than the conventional halbach array, and facilitate the rotor manufacturing.

[0041] Preferably, the second rotor core has a rotor inner magnetic bridge located on the inner circumferences of the main magnetic steel and the auxiliary magnetic steel.

[0042] Preferably, the main magnetic steel and the auxiliary magnetic steel are embedded in the second rotor core. Accordingly, the assembly is convenient, and the structural strength of the second rotor is guaranteed.

[0043] Preferably, the second rotor core extends two shoe parts at two top corner positions of the main magnetic steel close to the third air gap side to form a half-open main magnetic steel installation slot. On the one hand, it is convenient for the installation of the main magnetic steel. On the other hand, it reduces the magnetic circuit closed loop of the main magnetic steel close to the third air gap and reduces the magnetic leakage. Furthermore, the magnetic lines of force extend from the auxiliary magnetic steel to the third air gap and are more evenly diffused in the third air gap from the rotor shoe part, which cooperates with the stator slot, effectively reducing the torque fluctuation.

[0044] In an embodiment, the axial projection profile of the main magnetic steel is rectangular, the axial projection profile of the auxiliary magnetic steel is fan-shaped, the auxiliary magnetic steel is located at a radially inner position, the width of the main magnetic steel is w1, the radial length of the main magnetic steel is h1, the width of the radially inner side of the auxiliary magnetic steel is w5, the radial length of the auxiliary magnetic steel is h2, and the magnetic bridge width between the main magnetic steel and the auxiliary magnetic steel is w2, which satisfy the conditions 1.2 < w1 / w5 < 2.2, 1.5 < h1 / h2 < 2.4, and 0.08 < w2 / w1 < 0.15. The main permanent magnetic field at the third air gap is provided by the main magnetic steel, and the auxiliary magnetic steel plays a role in enhancing the field strength at the air gap. At the same time, by reasonable position placement and magnetization direction setting, the magnetic lines of force of the main magnetic steel far from the air gap end are twisted to reduce the magnetic leakage of the main magnetic steel. Accordingly, the magnetic field density at the third air gap is effectively improved, the magnetic leakage is reduced, and the output torque of the motor is improved, while the torque fluctuation is effectively suppressed.

[0045] In an embodiment, the axial projection profile of the main magnetic steel is rectangular, the axial projection profile of the auxiliary magnetic steel is fan-shaped, and the auxiliary magnetic steel is located at a radially inner position. Accordingly, the magnetic lines of force of the radially inner part of the main magnetic steel that are self-closed can be pulled back to the main magnetic circuit, the magnetic leakage is reduced, the magnetic force at the third air gap is stronger, and the output torque is larger.

[0046] In an embodiment, the axial projection profile of the main magnetic steel is rectangular, the axial projection profile of the auxiliary magnetic steel is fan-shaped, and the radial length of the auxiliary magnetic steel is equal to the radial length of the main magnetic steel. The radially outer side of the auxiliary magnetic steel core extends two shoe parts at two top corner positions of the main magnetic steel close to the air gap side to form a half-open main magnetic steel installation slot.

[0047] Preferably, the material grade of the main magnetic steel is higher than that of the auxiliary magnetic steel. The utilization rate of the rotor permanent magnetic force is maximized, and the cost waste is reduced. Due to the upper limit of the magnetic saturation of the magnetic conductive material used by the motor, the main permanent magnetic field at the air gap is provided by the main magnetic steel, and the auxiliary magnetic steel plays a role in enhancing the field strength at the air gap. At the same time, by reasonable position placement and magnetization direction setting, the magnetic lines of force of the main magnetic steel far from the air gap end are twisted to reduce the magnetic leakage of the main magnetic steel, and the main magnetic flux is provided by the main magnetic steel.

[0048] Preferably, the second stator core is formed with stator teeth of uniform distribution and equal width, winding wire slots are formed between adjacent stator teeth, and the winding wire slots have stator slots opening towards the third air gap; the winding generates a magnetic field with a pole pair number of P1, the number of stator teeth is P2, the second rotor has a pole pair number of P3, and P1+P3=P2. Further, the stator teeth are provided with stator shoe portions extending towards the stator slots opening near the third air gap. The stator teeth of equal width serve as both a stator magnetic circuit and for modulating the magnetic field of the second rotor, which helps with winding and can cooperate with the opening of the main magnetic steel to adjust the torque wave.

[0049] Preferably, the first rotor and the second rotor are arranged together in a cylindrical rotor shaft, and the cylindrical rotor shaft is sleeved on the radial outer side of the torque assembly. In this way, the structure of the first rotor and the second rotor can be simplified, and the concentricity of the first rotor and the second rotor can be increased.

[0050] In one embodiment, the motor portion and the magnetic transmission reduction device are coaxially and axially connected in series. In this way, the radial size of the entire center-mounted reduction motor can be reduced.

[0051] In one embodiment, the motor portion and the magnetic transmission reduction device partially overlap in the axial direction, and the motor portion is arranged inside the reduction device. In this way, the axial size of the entire center-mounted reduction motor can be reduced.

[0052] In one embodiment, the motor portion and the magnetic transmission reduction device overlap in the axial direction, and the entire motor is arranged inside the reduction device. In this way, the axial size of the entire center-mounted reduction motor can be minimized.

[0053] The present application achieves reduction by magnetic transmission. When the center-mounted reduction motor is in operation, the second rotor rotates by the magnetic flux generated by the second stator, and the first rotor rotates synchronously with the second rotor, thereby transmitting the power of the motor portion to the reduction device, which then outputs after reduction. Both the motor portion and the reduction device use magnetic transmission, which greatly increases the field strength in the space where the modulation ring portion is located, greatly increases the maximum output torque of the reduction device in the case where the installation space size is fixed, and further improves the operating efficiency of the motor and reduces the overall noise of the motor.

[0054] The center-mounted reduction motor of the present application achieves reduction by magnetic transmission, which reduces the size of the center-mounted motor and improves the rotation efficiency. Under the premise of ensuring the reduction ratio, the noise during operation is reduced, and the service life is extended. BRIEF DESCRIPTION OF DRAWINGS

[0055] FIG. 1 is a front projection schematic view of a center-mounted motor of a power-assisted bicycle according to an embodiment of the present application from one perspective;

[0056] FIG. 2 is a cross-sectional view of FIG. 1 along the A-A direction;

[0057] FIG. 3 is a cross-sectional view of FIG. 1 along the B-B direction;

[0058] Fig. 4 is a C-C sectional view of Fig. 1;

[0059] Fig. 5 is a structural exploded view of the middle motor shown in Fig. 1;

[0060] Fig. 6 is a cross-sectional view of a speed reduction device of the middle motor shown in Figs. 1-4;

[0061] Fig. 7 is a view of a first rotor magnetic pole assembly shown in Fig. 6;

[0062] Fig. 8 is a view of a modulating ring shown in Fig. 6;

[0063] Fig. 9 is a view of a first stator magnetic pole assembly shown in Fig. 6;

[0064] Fig. 10 is a view of a shielding ring shown in Fig. 6;

[0065] Fig. 11 is a structural exploded view of a first housing and a first stator shown in Fig. 5;

[0066] Fig. 12 is a cross-sectional view of a first stator magnetic pole assembly according to a first structure;

[0067] Fig. 13 is a view of a first stator permanent magnet constituting the first stator magnetic pole assembly shown in Fig. 12;

[0068] Fig. 14 is a cross-sectional view of a first stator magnetic pole assembly according to a second structure;

[0069] Fig. 15 is a view of a first stator permanent magnet constituting the first stator magnetic pole assembly shown in Fig. 14;

[0070] Fig. 16 is a cross-sectional view of a first stator magnetic pole assembly according to a third structure;

[0071] Fig. 17 is a view of a first stator permanent magnet constituting the first stator magnetic pole assembly shown in Fig. 16;

[0072] Fig. 18 is a structural exploded view of a first rotor and a second rotor shown in Fig. 5, which are disposed together in a single cylindrical rotor shaft;

[0073] Fig. 19 is a front projection view of the first rotor and the second rotor shown in Fig. 5, which are disposed together in a single cylindrical rotor shaft, from one perspective;

[0074] Fig. 20 is a D-D sectional view of Fig. 19;

[0075] Fig. 21 is an enlarged view of an E-E sectional view of Fig. 20;

[0076] Fig. 22 is a partial view of another structure of the second rotor and illustrates the magnetization directions of a main magnetic steel and an auxiliary magnetic steel;

[0077] Fig. 23 is a partial schematic view showing a third structure of the second rotor;

[0078] Fig. 24 is an exploded schematic view of the structure of the second rotor in Fig. 18;

[0079] Fig. 25 is a sectional view along F-F of Fig. 20;

[0080] Fig. 26 is a schematic view showing the magnetization direction of the permanent magnet of the first rotor;

[0081] Fig. 27 is a partial schematic view of the second stator core in Fig. 2;

[0082] Fig. 28 is a schematic view showing another structure of the second stator core of the present application;

[0083] Fig. 29 is a schematic view showing an axial front projection of the modulation ring shown in Fig. 5;

[0084] Fig. 30 is a sectional view along G-G of Fig. 29;

[0085] Fig. 31 is a sectional view along H-H of Fig. 30;

[0086] Fig. 32 is a partial schematic view showing another sectional structure of the modulation ring;

[0087] Fig. 33 is an exploded schematic view of the structure of the modulation ring shown in Fig. 5;

[0088] Fig. 34 is a schematic view of a bidirectional clutch of the present application;

[0089] Fig. 35 is a schematic view showing an axial front projection of the structure shown in Fig. 34;

[0090] Fig. 36 is a partial enlarged view of a sectional view along J-J of Fig. 35;

[0091] Fig. 37 is a sectional view along K-K of Fig. 36;

[0092] Fig. 38 is a schematic view showing the sectional structure of the mid-drive motor of the power-assisted bicycle according to Embodiment 2 of the present application;

[0093] Fig. 39 is a schematic view showing the sectional structure of the mid-drive motor of the power-assisted bicycle according to Embodiment 3 of the present application;

[0094] Fig. 40 is a schematic view showing the position of the mid-drive motor of the power-assisted bicycle of the present application on the bicycle;

[0095] Fig. 41 is an exploded schematic view showing the assembly structure of the mid-drive motor of the power-assisted bicycle of the present application and the frame of the bicycle;

[0096] Explanation of reference numerals in the drawings:

[0097] 100 housing, 101 first shell, 102 second shell, 103 first end cover, 104 second end cover, 105 shielding ring, 106 inner shell, 107 first bearing, 108 second bearing, 109 third bearing, 110 fourth bearing, 111 fifth bearing; shielding ring thickness H4, shielding ring inner diameter d5;

[0098] 200 torque assembly, 201 motor shaft, 202 torque sleeve;

[0099] 300 motor part,

[0100] 310 second stator, 311 second stator core, 312 winding, 313 stator tooth, 314 winding slot, 315 stator slot opening, 316 stator shoe,

[0101] 320 second rotor, 321 second rotor magnetic pole assembly, 322 main magnetic steel, 323 auxiliary magnetic steel, 324 interval magnetic bridge, 325 rotor inner magnetic bridge, 326 second rotor core, 327 opening, 328 rotor shoe,

[0102] Main magnetic steel width w1, main magnetic steel radial length h1, auxiliary magnetic steel inner edge width w5, auxiliary magnetic steel radial length h2, magnetic bridge width w2 between main magnetic steel and auxiliary magnetic steel;

[0103] 330 third air gap;

[0104] 400 magnetic transmission speed reduction device;

[0105] 410 first stator, 411 first stator magnetic pole assembly, 412 radial permanent magnet, 413 tangential permanent magnet, 414 large specification permanent magnet, 415 small specification permanent magnet, 416 angular center permanent magnet, 417 edge center permanent magnet,

[0106] Radial thickness of first stator permanent magnet H3, circumferential average width of first stator permanent magnet W3, included angle of two radial edges of small specification permanent magnet D2, radial thickness of small specification permanent magnet H5; included angle of two radial edges of large specification permanent magnet D3, radial thickness of large specification permanent magnet H6; outer diameter of first stator d5, inner diameter of first stator d4,

[0107] 420 first rotor, 421 first rotor magnetic pole assembly, 422 first rotor permanent magnet,

[0108] Radial thickness of first rotor permanent magnet H1, circumferential average width of first rotor permanent magnet W1, outer diameter of first rotor d1,

[0109] 430 modulation ring, 431 squirrel cage, 432 end plate, 433 connecting rod, 434 circular arc slot, 435 modulation tooth,

[0110] The included angle of the two radial edges of the modulation tooth is D1, the radial thickness of the modulation tooth is H2, and the circumferential average width of the modulation tooth is W2,

[0111] 440 first air gap,

[0112] 450 second air gap;

[0113] 500 bidirectional clutch, 501 cylindrical output shaft, 502 inner sleeve, 503 outer sleeve, 504 first clutch member, 505 second clutch member;

[0114] 601 sensor, 602 controller;

[0115] 700 cylindrical rotor shaft;

[0116] 800 power-assisted bicycle, 801 frame, 802 crank, 803 pedal, 804 driving sprocket, 805 driving sprocket locking nut, 806 chain, 807 driving wheel, 808 driven sprocket;

[0117] 900 power-assisted bicycle middle motor. DETAILED DESCRIPTION

[0118] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0119] The terms "include" and "have" and any variations thereof in the specification and claims of the present application are intended to cover the non-exclusive inclusion, for example, a method or product including a series of technical features is not limited to only those clearly listed, but can also include other technical features not clearly listed that can be included in the method or product.

[0120] In the description of the present application, it should be understood that the technical features defined by the terms "first", "second", "third" and the like have the concept of order, only for the purpose of clearly describing the defined technical features, so that the defined technical features can be clearly distinguished from other technical features, and it does not represent the actual implementation of such naming, therefore it cannot be understood as a limitation of the present application.

[0121] The present application will be described in detail below with reference to specific embodiments and drawings.

[0122] Power-assisted bicycles are well known, which are driven forward by transmitting the torque generated by the pedals to the wheels. The power-assisted bicycles are provided with a middle motor, which provides external power without affecting the pedals, so that the rider can be more labor-saving. Compared with the hub motor, the hub motor is coaxial with the wheel, which directly transmits power to the wheel. When the vehicle slides forward, the hub motor will generate resistance to the vehicle. The middle motor is installed in the middle of the frame and transmits power to the wheel through the transmission mechanism, so that the bicycle is basically not affected by the middle motor when sliding forward, and the bicycle can slide a longer distance.

[0123] The various embodiments of the present application provide such a power-assisted bicycle middle motor.

[0124] Embodiment 1

[0125] As shown in FIGS. 1-5, the power-assisted bicycle middle motor of the present embodiment includes a housing 100, a torque assembly 200, a motor portion 300, a magnetic transmission deceleration device 400, a bidirectional clutch 500, a sensor 601 and a controller 602.

[0126] The housing 100 serves as the assembly base of the torque assembly, the motor portion, the magnetic transmission deceleration device and the bidirectional clutch, and is also used to assemble the middle deceleration motor on the bicycle. In the present embodiment, in order to facilitate assembly, as shown in FIG. 5, the housing 100 includes a first housing 101, a second housing 102 and a first end cover 103 assembled together by fasteners.

[0127] The torque assembly 200 penetrates the housing 100 and extends out of the housing at both ends to receive external torque, such as the torque generated by the pedals when riding. In the present embodiment, 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 spline, so that the torque sleeve rotates with the motor shaft. A fixed inner shell 106 is arranged outside the torque assembly, one end of the inner shell 106 is fixed with the second end cover 104, so that the torque assembly can rotate relative to the inner shell.

[0128] The motor portion 300 is circled by double-dot dash line in FIG. 4, the motor portion 300 includes a second stator 310 and a second rotor 320. The second rotor 302 is located inside the second stator 310 and coaxial with the second stator. The third air gap 330 is maintained between the second rotor 320 and the second stator 310. In particular, the axial height of the second rotor permanent magnet is consistent with the axial thickness of the second stator core, which can ensure the compact axial size of the product.

[0129] The second stator 310 includes a second stator core 311 and a winding 312 wound on the second stator core 311, which are arranged in the second housing 102 of the casing. As shown in Figs. 27 and 28, the second stator core 311 is formed with stator teeth 313 of equal width and arranged at equal intervals, and winding wire slots 314 are formed between adjacent stator teeth 313, the winding wire slots 314 having stator slots 315 facing the third air gap. The winding generates a magnetic field with a number of pole pairs P1, the number of stator teeth P2, and the number of pole pairs of the second rotor P3, and P1+P3=P2. The stator teeth 313 are provided with stator shoe portions 316 extending toward the stator slots 315 near the third air gap.

[0130] An alternating signal is applied to the winding 312 to generate a varying magnetic field for driving the second rotor to rotate.

[0131] As shown in Figs. 18-24, the second rotor 320 includes a ring-shaped second rotor magnetic pole assembly 321 for providing a second rotor magnetic field rotating with the second rotor. The second rotor magnetic pole assembly 321 includes main magnetic steel 322 and auxiliary magnetic steel 323 arranged at intervals on the circumference of a second rotor core 326. The main magnetic steel is magnetized tangentially, and the auxiliary magnetic steel is magnetized radially, as indicated by arrows in Figs. 22 and 23. The second rotor core 326 has an interval magnetic bridge 324 between the main magnetic steel 322 and the auxiliary magnetic steel 323 for isolating the main magnetic steel from the auxiliary magnetic steel. The second rotor core 326 has a rotor inner magnetic bridge 325 on the inner circumference of the main magnetic steel and the auxiliary magnetic steel. Furthermore, the interval magnetic bridge 324 and the rotor inner magnetic bridge 325 are formed on the second rotor core 326, and the main magnetic steel 322 and the auxiliary magnetic steel 323 are embedded in the second rotor core 326. The second rotor core 326 is provided with an opening 327 at a position corresponding to the main magnetic steel 322 near the third air gap 330, and two opposite rotor shoe portions 328 are formed on two edges of the opening. Moreover, the material grade of the main magnetic steel is higher than that of the auxiliary magnetic steel.

[0132] As shown in FIG. 21, the axial projection profile of the main magnetic steel 322 is rectangular, and the axial projection profile of the auxiliary magnetic steel 323 is fan-shaped. The auxiliary magnetic steel 323 is located at a radially inner position and adjoins the inner magnetic bridge 325 of the rotor together with the main magnetic steel 322, and the inner magnetic bridge 325 of the rotor is embodied as a circular ring with uniform thickness. The main magnetic steel width is w1, the main magnetic steel radial length is h1, the auxiliary magnetic steel inner edge width is w5, the auxiliary magnetic steel radial length is h2, and the magnetic bridge width between the main magnetic steel and the auxiliary magnetic steel is w2, which satisfy the conditions 1.2 < w1 / w5 < 2.2, 1.5 < h1 / h2 < 2.4, and 0.08 < w2 / w1 < 0.15. Alternatively, as shown in FIG. 22, the axial projection profile of the main magnetic steel 322 is rectangular, and the axial projection profile of the auxiliary magnetic steel 323 is rectangular. The auxiliary magnetic steel is located at a radially inner position and adjoins the inner magnetic bridge of the rotor together with the main magnetic steel, and the inner magnetic bridge of the rotor is embodied as a circular ring with uniform thickness. Alternatively, as shown in FIG. 23, the axial projection profile of the main magnetic steel 322 is rectangular, and the axial projection profile of the auxiliary magnetic steel 323 is fan-shaped. The auxiliary magnetic steel radial length is equal to the main magnetic steel radial length.

[0133] As shown in FIG. 6, the magnetic transmission speed reduction device 400 includes a first stator 410, a first rotor 420, and a modulation ring 430.

[0134] As shown in FIG. 11, the first stator 410 is fixed in the first shell 101 of the shell, and the inner wall of the first shell 101 is embedded with a steel ring for use as a shielding ring 105 to shield the magnetic field of the first rotor. The first stator 410 includes a ring-shaped first stator magnetic pole assembly 411 for providing a fixed first stator magnetic field. As shown in FIGS. 12-17, the magnetic field of the first stator magnetic pole assembly 411 is distributed according to a Halbach array. The first stator magnetic pole assembly 411 is assembled by first stator permanent magnets after being magnetized in blocks. A single pole is divided into two blocks, which are radially magnetized and tangentially magnetized, respectively, and the whole is inwardly magnetized. Moreover, the shielding ring is axially divided into N segments, the axial length of each segment of the shielding ring is L1, the axial length of the first stator magnetic pole assembly is L, all the shielding rings are uniformly distributed along the axial direction, the shielding ring at the end is aligned with the first stator magnetic pole assembly, the distance between the end faces of the two adjacent shielding rings is (L-N*L1) / (N-1), and L1>0.65*(L / N), N<10.

[0135] The first stator permanent magnet is configured in any of the following ways:

[0136] (1) As shown in FIGS. 12-13, the axial projection profile of each first stator permanent magnet is a sector with the same size, the first stator permanent magnet is divided into radial permanent magnets 412 and tangential permanent magnets 413, the radial permanent magnets are radially magnetized, and the tangential permanent magnets are tangentially magnetized. The arrows in the figure represent the magnetization direction. The radial permanent magnets and the tangential permanent magnets are spliced into the first stator magnetic pole assembly with an interval, the magnetization directions of the two adjacent radial permanent magnets are opposite, and the magnetization directions of the two adjacent tangential permanent magnets are opposite; the radial thickness of the first stator permanent magnet is H3, the circumferential average width of the first stator permanent magnet is W3, and W3 / H3 = 0.52-0.6; the circumferential average width of the first stator permanent magnet is the chord length width confirmed by the geometric center of the axial projection profile of the first stator permanent magnet.

[0137] (2) As shown in FIGS. 14-15, the axial projection profile of each first stator permanent magnet is a sector, the first stator permanent magnet is divided into large-size permanent magnets 414 and small-size permanent magnets 415, the large-size permanent magnets are radially magnetized, and the small-size permanent magnets are tangentially magnetized. The arrows in the figure represent the magnetization direction. The large-size permanent magnets and the small-size permanent magnets are spliced into the first stator magnetic pole assembly with an interval, the magnetization directions of the two adjacent large-size permanent magnets are opposite, and the magnetization directions of the two adjacent small-size permanent magnets are opposite; the included angle of the two radial edges of the small-size permanent magnet is D2, and the radial thickness of the small-size permanent magnet is H5; the included angle of the two radial edges of the large-size permanent magnet is D3, and the radial thickness of the large-size permanent magnet is H6; and 1.5

[0138] (3) As shown in FIGS. 16-17, the axial projection profile of each first stator permanent magnet is a triangle, the first stator permanent magnet is divided into angular permanent magnets 416 and edge permanent magnets 417, the edge permanent magnets are radially magnetized, and the angular permanent magnets are tangentially magnetized. The arrows in the figure represent the magnetization direction. The angular permanent magnets and the edge permanent magnets are spliced into the first stator magnetic pole assembly with an interval, the magnetization directions of the two adjacent angular permanent magnets are opposite, and the magnetization directions of the two adjacent edge permanent magnets are opposite, the edges of the angular permanent magnets constitute the outer edges of the first stator magnetic pole assembly, the edges of the edge permanent magnets constitute the inner edges of the first stator magnetic pole assembly, and the adjacent edges of the angular permanent magnets and the edge permanent magnets are equal in length and completely aligned; the outer diameter of the first stator is d5, the inner diameter of the first stator is d4, the number of pole pairs of the first stator is p3, and 0.8×d4×sin(360deg / 4p3) < d5-d4 < 0.9×d4×sin(360deg / 4p3).

[0139] As shown in FIG. 5, FIG. 18-20, FIG. 25-26, the first rotor 420 comprises a first rotor magnetic pole assembly 421 for providing a first rotor magnetic field rotating with the first rotor 420, the first rotor 420 is located inside and coaxial with the first stator 410. The magnetic field of the first rotor magnetic pole assembly 421 is distributed according to a Halbach Array. The first rotor magnetic pole assembly is assembled by first rotor permanent magnets 422, each single pole is divided into four pieces, and the whole piece is magnetized outward. The first rotor has p1 pole pairs, and contains 8xp1 first rotor permanent magnets. The magnetization direction of adjacent two first rotor permanent magnets is different by (45-360 / (8xp1)) degrees. The arrow in FIG. 26 represents the magnetization direction of adjacent first rotor permanent magnets, which changes by one degree in a certain direction (such as clockwise or counterclockwise) in the axial projection plane, so that the magnetic pole directions of adjacent single poles are opposite. As shown in FIG. 26, when the four pieces of first rotor permanent magnets constitute a single pole, the magnetic pole directions of the two adjacent single poles are opposite. As shown in FIG. 7, the axial projection profile of the first rotor permanent magnet is a sector, and each first rotor permanent magnet has the same size, with a radial thickness H1 and a circumferential average width W1, H1 / W1=0.8-1.5. Among them, the circumferential average width of the first rotor permanent magnet is the chord length width identified by the geometric center of the axial projection profile of the first rotor permanent magnet.

[0140] In the illustrated structure, the first rotor 420 and the second rotor 320 are jointly arranged in the same cylindrical rotor shaft 700, and the first rotor is synchronously rotated by the second rotor.

[0141] Furthermore, there is a formula relationship between the thickness H4 of the shielding ring 105 (see FIG. 10), the outer diameter d1 of the first rotor (see FIG. 25), the inner diameter d5 of the shielding ring (see FIG. 10), and the pole pair number p1 of the first rotor: d5-d1

[0142] The modulation ring 430 is located between the first rotor 420 and the first stator 410, and is coaxial with the first rotor 420 and the first stator 410. The modulation ring 430 maintains a first air gap 440 with the first stator 410 and a second air gap 450 with the first rotor 420.

[0143] As shown in FIG. 5, FIG. 29-33, the modulation ring 430 comprises modulation teeth 435 and a squirrel cage 431. The modulation teeth 431 are made of high-saturation magnetic induction material such as 1J22 iron-cobalt-vanadium soft magnetic alloy or DT4 electromagnetic pure iron.

[0144] The squirrel cage 431 comprises two end plates 432 and a plurality of connecting rods 433 connected between the two end plates, the connecting rods extending axially and being distributed along the circumference, and the modulation teeth 435 are fixed in the gaps between the adjacent connecting rods 433. The gaps between the adjacent connecting rods 433, in which the modulation teeth 435 are fixed, can be inlaid between the adjacent connecting rods 433, or the modulation ring can be completed by injection molding, the squirrel cage is a composite material, the squirrel cage end plate and the modulation teeth are put into a mold for one-piece injection molding, thereby ensuring the size and strength requirements of the modulation teeth, the squirrel cage and the squirrel cage end plate.

[0145] Moreover, each modulation tooth has a consistent size, the total number of the modulation teeth is p2, the axial projection profile of the modulation teeth is a sector, the included angle of the two radial edges of the modulation teeth is D1, and D1 / (360deg / p2)=0.5-0.6; the radial thickness of the modulation teeth is H2, the circumferential average width of the modulation teeth is W2, and H2 / W2=0.55-1.3. The circumferential average width of the modulation teeth is the chord length width identified by the circle ring in which the geometric center of the axial projection profile of the modulation teeth is located. In another embodiment, alternatively, the connecting rods 433 are cylindrical, and the circular arc grooves 434 are opened at the middle positions of the two circumferential sides of the modulation teeth 435, the circular arc grooves 434 are fitted to the connecting rod surface to support the connecting rods and the cylindrical shape with each other.

[0146] Further, the first rotor pole pair number is p1, the total number of the modulation teeth is p2, the first stator pole pair number is p3, and p1=|p2-p3|.

[0147] The first stator and the first rotor are configured with different pole pair numbers, the modulation ring performs magnetic field modulation on the magnetic motive force of the first rotor, the magnetic field of the first air gap is coupled with the magnetic field of the second air gap, the rotation from the first rotor is decelerated through the modulation ring and output coaxially with the first rotor to increase the torque.

[0148] As shown in Figs. 4-5, 34-37, the bi-directional clutch 500 is arranged between the torque assembly 200 and the modulation ring 430. The bi-directional clutch has a cylindrical output shaft 501 extending out of the housing for outputting torque, which is alternatively transmitted by the torque assembly or by the modulation ring. The bi-directional clutch 500 comprises an inner sleeve 502 arranged in the torque assembly 200 by means of a spline fit and rotates with the torque assembly, an outer sleeve 503 fixedly arranged in the modulation ring by means of a die-cast with one end face of the modulation ring and rotates with the modulation ring, the cylindrical output shaft 501 is sleeved on the radially outer side of the inner sleeve 502, the outer sleeve 503 is sleeved on the radially outer side of the cylindrical output shaft 501, a plurality of first clutch elements 504 are distributed between the cylindrical output shaft 501 and the inner sleeve 502, and a plurality of second clutch elements 505 are distributed between the cylindrical output shaft 501 and the outer sleeve 503. The first clutch elements 504 and the second clutch elements 505 are arranged in opposite directions. In order to make the first clutch elements and the second clutch elements evenly distributed in the circumferential direction to facilitate the operation of the bi-directional clutch, adjacent first clutch elements are separated in the circumferential direction by rollers and filled with the circumferential gap between the cylindrical output shaft and the inner sleeve together with the rollers, and adjacent second clutch elements are separated in the circumferential direction by rollers and filled with the circumferential gap between the cylindrical output shaft and the outer sleeve together with the rollers. In the structure shown in the figure, the first clutch elements and the second clutch elements have the same cross-sectional structure, and the first clutch elements and the second clutch elements are arranged in opposite directions, which is manifested as their installation directions being opposite.

[0149] In Fig. 4, the first clutch elements 504 and the second clutch elements 505 are located at different axial positions, and the first clutch elements and the second clutch elements are axially offset. In Figs. 35-37, the first clutch elements 504 and the second clutch elements 505 are located at the same axial position and correspond in the radial direction. Either structure can be selected according to requirements.

[0150] As described in the foregoing structure, the first bearing 107 is arranged between the pivot shaft 201 and the second end cover 104 of the second housing, the second bearing 108 is arranged between the pivot shaft 201 and the cylindrical output shaft 501 of the bi-directional clutch, the third bearing 109 is arranged between the cylindrical rotor shaft 700 and the second end cover 104 of the second housing, the fourth bearing 110 is arranged between the cylindrical rotor shaft 700 and the cylindrical output shaft 501 of the bi-directional clutch, and the fifth bearing 111 is arranged between the cylindrical rotor shaft 700 and the first end cover 103, so that the torque assembly 200, the first rotor 420 and the second rotor 320 can all rotate relative to the housing 100, and the cylindrical output shaft 501 of the bi-directional clutch can rotate relative to the torque assembly and the modulation ring.

[0151] Referring to Fig. 36, when the inner sleeve 502 is rotated clockwise by the pedal, the first clutch 504 is subjected to friction and has a tendency to rotate counterclockwise, the long diameter direction of the first clutch is pressed between the cylindrical output shaft 501 and the inner sleeve 502, the clockwise rotation of the inner sleeve 502 is transmitted to the cylindrical output shaft 501 by the first clutch, and the cylindrical output shaft 501 is rotated clockwise. Further, when the cylindrical output shaft 501 is rotated clockwise, the second clutch 505 is subjected to friction and has a tendency to rotate counterclockwise, the short diameter direction of the second clutch corresponds to the cylindrical output shaft 501 and the outer sleeve 503, the second clutch 505 does not transmit the clockwise rotation of the cylindrical output shaft to the outer sleeve 503, and the torque of the torque assembly is not transmitted to the outer sleeve and the modulation ring. This situation is suitable for driving the bicycle forward by the pedal.

[0152] Referring to Fig. 36, when the inner sleeve 502 is rotated clockwise by the pedal, the first clutch 504 is subjected to friction and has a tendency to rotate counterclockwise, the long diameter direction of the first clutch is pressed between the cylindrical output shaft 501 and the inner sleeve 502, the clockwise rotation of the inner sleeve 502 is transmitted to the cylindrical output shaft 501 by the first clutch, and the cylindrical output shaft 501 is rotated clockwise. Further, when the cylindrical output shaft 501 is rotated clockwise, the second clutch 505 is subjected to friction and has a tendency to rotate counterclockwise, the short diameter direction of the second clutch corresponds to the cylindrical output shaft 501 and the outer sleeve 503, the second clutch 505 does not transmit the clockwise rotation of the cylindrical output shaft to the outer sleeve 503, and the torque of the torque assembly is not transmitted to the outer sleeve and the modulation ring. This situation is suitable for driving the bicycle forward by the pedal.

[0153] During the riding of the bicycle, when the bicycle slides forward, the power transmission between the driving sprocket and the driven sprocket of the middle motor is cut off according to the one-way clutch mechanism of the transmission mechanism between the middle motor and the driving wheel, such as the ratchet and pawl mechanism arranged in the driving wheel and the driven sprocket, and the pedal power or the motor power does not need to be provided to the bicycle.

[0154] When the bicycle is moved backwards during the cycling process, such as when the cyclist turns around, the bicycle drive wheel is connected to the cylindrical output shaft through the transmission mechanism. When the bicycle moves forward, the cylindrical output shaft rotates clockwise. When the bicycle moves backwards, the drive wheel of the bicycle rotates the cylindrical output shaft counterclockwise. The counterclockwise rotation of the cylindrical output shaft drives the inner sleeve 502 and the torque assembly 200 to rotate counterclockwise through the first clutch 504, and drives the outer sleeve and the modulation ring to rotate counterclockwise through the second clutch 505. At this time, the middle motor is not powered and is in a non-working state.

[0155] During the cycling process, the driving of the bicycle by the pedals and the driving of the bicycle by the middle motor can be alternated. Therefore, the middle motor includes a sensor 601 and a controller 602. The controller drives the motor according to the signal of the torque assembly receiving the pedal driving torque provided by the sensor. Therefore, when the middle motor is installed on the bicycle, the cyclist can drive the motor to drive the bicycle forward by pedaling. As shown in FIG. 5, the sensor 601 is arranged on the inner shell 106 to detect the torque assembly receiving the pedal driving torque. The pedal driving torque can be a pressure signal or the rotation of the torque assembly. The controller 602 can be arranged on the middle motor or the vehicle. When the cyclist wants to drive the bicycle forward, the cyclist pedals the pedals, and the pedal driving torque generated by the pedal action is transmitted to the torque assembly through the crank. The sensor detects the rotation trend of the torque assembly or the pressure signal or the rotation signal generated by the rotation and provides the signal to the controller.

[0156] In the embodiment, the permanent magnets of the magnetic pole assemblies of the first stator, the first rotor and the second rotor are distributed along the circumference on the axial projection surface.

[0157] In the embodiment, the motor part 300 and the magnetic transmission reduction device 400 are coaxially connected in series in the axial direction, as shown in FIG. 4.

[0158] Embodiment 2

[0159] As shown in FIG. 38, the difference between the embodiment and the embodiment 1 is that the motor part 300 and the reduction device 400 are partially overlapped in the axial direction, and the motor part is arranged inside the reduction device. The rest of the structure is the same as that of the embodiment 1, and is not described herein.

[0160] Embodiment 3

[0161] As shown in FIG. 39, the difference between the embodiment and the embodiment 1 is that the motor part 300 and the reduction device 400 are overlapped in the axial direction, and the motor part is arranged inside the reduction device. The rest of the structure is the same as that of the embodiment 1, and is not described herein.

[0162] The middle motor of the foregoing embodiments is fastened to the frame by fasteners, as shown in Fig. 41, and a crank is fitted at each end of the pivot, and a pedal 803 is fitted on each crank, and a driving sprocket 804 is fastened to the cylindrical output shaft 501 of the bidirectional clutch by a compression sleeve 805. As shown in Fig. 40, a chain 806 is fitted around the driving sprocket 804 and a driven sprocket 808 of a driving wheel 807, and the bicycle can be ridden as described above.

[0163] The application utilizes typical magnetic rotation, a modulation ring is placed between the first rotor and the first stator, the three are contactless, and power is transmitted by magnetic field coupling, the first rotor has fewer magnetic poles, the first stator has more magnetic poles, the first stator and the first rotor are arranged in the form of Halbach Array, the modulation ring is composed of modulation teeth of high permeability material and a squirrel cage of non-permeable material, the first stator is inwardly magnetized, the first rotor is outwardly magnetized, the first air gap is between the modulation ring and the first stator, the second air gap is between the modulation ring and the first rotor, the first rotor and the second rotor of the motor are axially integrated, the motor second rotor drives the first rotor to rotate during operation, the magnetic fields generated by the first rotor and the first stator are modulated by the modulation ring and generate a series of spatial harmonic magnetic fields in the first air gap and the second air gap, and the asynchronous spatial magnetic fields with the largest amplitude in the first air gap and the second air gap can match the pole pairs of the first stator and the first rotor, respectively, and a stable output torque is generated on the modulation ring through magnetic field coupling, the function of speed reduction and torque amplification is achieved. Due to the frictionless characteristics of magnetic transmission, combined with the super high torque density brought by the magnetic concentration structure and high permeability material designed by the application, the system efficiency is improved and the operating noise is reduced.

Claims

1. A magnetic drive speed reduction device, characterized in that... It includes a first stator (410), a first rotor (420), and a modulation ring (430), wherein A first stator (410) includes a first stator magnetic pole assembly (411) for providing a first stator magnetic field; A first rotor (420) includes a first rotor magnetic pole assembly (421) for providing a first rotor magnetic field that rotates with the first rotor. The first rotor (420) is located inside the modulation ring (430) and is coaxial with the modulation ring. A modulation ring (430) is located between the first rotor and the first stator. The modulation ring is coaxial with the first rotor and the first stator. A first air gap (440) is maintained between the modulation ring and the first stator, and a second air gap (450) is maintained between the modulation ring and the first rotor. The first stator (410) and the first rotor (420) are configured with different numbers of pole pairs, so that the magnetic field of the first air gap is coupled with the magnetic field of the second air gap, and the rotation from the first rotor is decelerated and output by the modulation ring.

2. The magnetic drive speed reduction device according to claim 1, characterized in that: The magnetic field of the first stator (410) is focused inward, while the magnetic field of the first rotor (420) is focused outward.

3. The magnetic drive reduction device according to claim 1 or 2, characterized in that: The first rotor magnetic pole assembly is formed by splicing together the first rotor permanent magnet (422) after being magnetized in sections. The single pole is divided into four sections, and the whole magnetizes outward. The first stator magnetic pole assembly is formed by splicing together the first stator permanent magnet after it is magnetized in sections. Each pole is divided into two parts, which are radially magnetized and tangentially magnetized, and the whole is magnetized inward.

4. The magnetic drive speed reduction device according to claim 3, characterized in that: The first rotor has p1 pole pairs and contains 8×p1 first rotor permanent magnets. The magnetization directions of two adjacent first rotor permanent magnets differ by (45-360 / (8×p1)) degrees.

5. The magnetic drive speed reduction device according to claim 3, characterized in that: The axial projection profile of the first rotor permanent magnet (422) is fan-shaped. Each first rotor permanent magnet has the same size, with a radial thickness of H1 and a circumferential average width of W1, where H1 / W1 = 0.8-1.

5.

6. The magnetic drive speed reduction device according to claim 3, characterized in that: The first stator permanent magnet is configured in any of the following ways: (1) The axial projection profile of each first stator permanent magnet is a fan shape and the same size. The first stator permanent magnet is divided into radial permanent magnet (412) and tangential permanent magnet (413). The radial permanent magnet is radially magnetized and the tangential permanent magnet is tangentially magnetized. The radial permanent magnet and the tangential permanent magnet are spliced ​​together at intervals to form the first stator magnetic pole assembly. The magnetization directions of two adjacent radial permanent magnets are opposite and the magnetization directions of two adjacent tangential permanent magnets are opposite. The radial thickness of the first stator permanent magnet is H3 and the circumferential average width of the first stator permanent magnet is W3, and W3 / H3=0.52-0.6; (2) The axial projection contour of each first stator permanent magnet is a fan shape. The first stator permanent magnet is divided into a large-size permanent magnet (414) and a small-size permanent magnet (415). The large-size permanent magnet is radially magnetized and the small-size permanent magnet is tangentially magnetized. The large-size permanent magnet and the small-size permanent magnet are spliced ​​together at intervals to form the first stator magnetic pole assembly. The magnetization directions of adjacent large-size permanent magnets are opposite, and the magnetization directions of adjacent small-size permanent magnets are opposite. The included angle between the two radial sides of the small-size permanent magnet is D2, and the radial thickness of the small-size permanent magnet is H5. The included angle between the two radial sides of the large-size permanent magnet is D3, and the radial thickness of the large-size permanent magnet is H6. And 1.5 < D3 / D2 < 2.2, 0.4 < H6 / H5 < 0.

6. (3) The axial projection contour of each first stator permanent magnet is a triangle. The first stator permanent magnet is divided into angular radial permanent magnets (416) and side radial permanent magnets (417). The side radial permanent magnets are radially magnetized, and the angular radial permanent magnets are tangentially magnetized. The angular radial permanent magnets and the side radial permanent magnets are spliced ​​together at intervals to form the first stator magnetic pole assembly. The magnetization directions of two adjacent angular radial permanent magnets are opposite, and the magnetization directions of two adjacent side radial permanent magnets are opposite. The sides of the first stator magnetic pole assembly form the outer side, and the sides of the pericentric permanent magnet form the inner side. The adjacent sides of the angular pericentric permanent magnet and the pericentric permanent magnet are of equal length and perfectly aligned. The outer diameter of the first stator is d5, the inner diameter of the first stator is d4, the number of pole pairs of the first stator is p3, and 0.8×d4×sin(360deg / 4p3)<d5-d4<0.9×d4×sin(360deg / 4p3).

7. The magnetic drive reduction device according to claim 1 or 2, characterized in that: The modulation ring (430) includes modulation teeth (435) made of a material with high saturation magnetic induction intensity.

8. The magnetic drive speed reduction device according to claim 7, characterized in that: The modulation ring (430) includes a cage (431), which includes two end plates (432) and a number of connecting rods (433) connected between the two end plates. The connecting rods extend axially and are distributed circumferentially. Modulation teeth (435) are fixed in the gap between adjacent connecting rods (433).

9. The magnetic drive speed reduction device according to claim 7, characterized in that: Each modulation tooth (435) has the same size, the total number of modulation teeth is p2, the axial projection profile of the modulation tooth is fan-shaped, the included angle between the two radial sides of the modulation tooth is D1, and D1 / (360deg / p2)=0.5-0.6; the radial thickness of the modulation tooth is H2, the circumferential average width of the modulation tooth is W2, and H2 / W2=0.55-1.

3.

10. The magnetic drive speed reduction device according to claim 7, characterized in that: The connecting rod (433) is cylindrical, and the middle of the two sides of the modulation tooth (435) has an arc groove. The arc groove fits into the surface of the connecting rod so that the connecting rod and the cylindrical shape support each other.

11. The magnetic drive speed reduction device according to claim 7, characterized in that: The first rotor has p1 pole pairs, the total number of modulation teeth is p2, the first stator has p3 pole pairs, and p1 = |p2 - p3|.

12. The magnetic drive speed reduction device according to claim 1, characterized in that: The first stator (410) is fixed to the housing (100), and a shielding ring (105) is embedded in the inner wall of the housing to reduce magnetic leakage to the outside of the housing.

13. The magnetic drive speed reduction device according to claim 12, characterized in that: The shielding ring thickness H4, the outer diameter of the first rotor d1, the inner diameter of the shielding ring d5, and the number of pole pairs of the first rotor p1 are related by the following formula: d5-d1<d1×sin(360deg / 4p1), H4≥0.185×d1×(1+sin(360deg / 4p1))-0.5×d5.

14. The magnetic drive speed reduction device according to claim 12, characterized in that: The shielding ring (105) is divided into N segments along the axial direction. The axial length of each shielding ring segment is L1. The axial length of the first stator magnetic pole assembly is L. All shielding rings are evenly distributed along the axial direction. The shielding rings located at the ends are aligned with the first stator magnetic pole assembly. The distance between the end faces of every two shielding ring segments is (LN*L1) / (N-1), and L1>0.65*(L / N), N<10.

15. A mid-mounted motor in a power-assisted bicycle, characterized by: include: Casing (100); A torque assembly (200) extends through the housing and extends out of the housing at both ends to receive external torque; The motor section (300) includes a second stator (310) and a second rotor (320). The second stator includes an iron core (311) attached to the housing and a winding (312) wound around the iron core. When the winding is energized, it generates a rotating magnetic field. The second rotor (320) is used to provide a permanent magnet magnetic field that matches the electromagnetic field generated by the stator winding. The second rotor (320) is located inside the second stator (310) and is coaxial with the second stator. A third air gap (330) is maintained between the second rotor and the second stator. The magnetic drive reduction device (400) according to any one of claims 1-14, wherein the first rotor (420) is driven to rotate synchronously by the second rotor (320); A two-way clutch (500) is disposed between a torque assembly (200) and a modulation ring (430) for selectively transmitting torque to it by the torque assembly or by the modulation ring. The two-way clutch has a cylindrical output shaft (501) extending out of the housing for outputting torque, the cylindrical output shaft being sleeved on the radially outer side of one end (200) of the torque assembly.

16. The mid-mounted motor for a power-assisted bicycle according to claim 15, characterized in that: The mid-mounted geared motor includes a sensor (601) and a controller (602). The controller commands the motor to work based on the torque signal provided by the sensor.

17. The mid-mounted motor for a power-assisted bicycle according to claim 16, characterized in that: A fixed inner shell (106) is configured on the outside of the torque assembly (200), and a sensor (601) is located in the inner shell to detect torque signals and receive pedal drive torque.

18. The mid-mounted motor for a power-assisted bicycle according to claim 15, characterized in that: The two-way clutch (500) includes an inner sleeve (502), an outer sleeve (503), a plurality of first clutch elements (504), and a plurality of second clutch elements (505). The inner sleeve (502) is disposed on the torque assembly (200) and rotates together with the torque assembly. The outer sleeve (503) is disposed 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), and the outer sleeve (503) is sleeved on the radial outer side of the cylindrical output shaft (501). The plurality of first clutch elements (504) are distributed between the cylindrical output shaft (501) and the inner sleeve (502), and the plurality of second clutch elements (505) are distributed between the cylindrical output shaft (501) and the outer sleeve (503). The first clutch elements (504) and the second clutch elements (505) are arranged in opposite directions.

19. The bicycle mid-mounted geared motor according to claim 15, characterized in that: The torque assembly (200) includes a motor shaft (201) and a torque sleeve (202) that is sleeved on the motor shaft and rotates with the motor shaft.

20. The mid-mounted geared motor for a power-assisted bicycle according to claim 15, characterized in that: The second rotor (320) includes a second rotor core (326) and main magnets (322) and auxiliary magnets (323) spaced apart on the circumference of the second rotor core (326). The main magnets are tangentially magnetized and the auxiliary magnets are radially magnetized. The second rotor core (326) has a spacer magnetic bridge (324) located between the main magnets and the auxiliary magnets to isolate the main magnets and the auxiliary magnets.

21. The mid-mounted motor for a power-assisted bicycle according to claim 15, characterized in that: The second rotor core (326) has an inner rotor magnetic bridge (325) located on the inner circumference of the main magnet and the auxiliary magnet.

22. The mid-mounted motor for a power-assisted bicycle according to claim 15, characterized in that: The main magnet (322) and auxiliary magnet (323) are embedded in the second rotor core (326).

23. The mid-mounted motor for a power-assisted bicycle according to claim 20, characterized in that: The second rotor core (326) extends two shoe-shaped parts at the two apex positions of the main magnet near the third air gap side, forming a semi-open main magnet mounting groove.

24. The mid-drive motor for a power-assisted bicycle according to any one of claims 20-23, characterized in that: the main... The axial projection profile of the magnet (322) is rectangular, and the axial projection profile of the auxiliary magnet (323) is fan-shaped. The auxiliary magnet is located radially inward. The width of the main magnet is w1, the radial length of the main magnet is h1, the width of the inner side of the auxiliary magnet is w5, the radial length of the auxiliary magnet is h2, and the width of the magnetic bridge between the main magnet and the auxiliary magnet is w2, which satisfy the conditions 1.2 < w1 / w5 < 2.2, 1.5 < h1 / h2 < 2.4, and 0.08 < w2 / w1 < 0.

15.

25. The mid-mounted motor for a power-assisted bicycle according to any one of claims 20-23, characterized in that: The axial projection profile of the main magnet is rectangular, the axial projection profile of the auxiliary magnet is rectangular, and the auxiliary magnet is located radially inward.

26. The mid-drive motor for a power-assisted bicycle according to any one of claims 20-23, characterized in that: the main... The axial projection profile of the main magnet is rectangular, the axial projection profile of the auxiliary magnet is fan-shaped, and the radial length of the auxiliary magnet is equal to the radial length of the main magnet.

27. The mid-mounted motor for a power-assisted bicycle according to any one of claims 20-23, characterized in that: The material grade of the main magnet is higher than that of the auxiliary magnet.

28. The mid-mounted motor for a power-assisted bicycle according to any one of claims 20-23, characterized in that: The second stator core (311) has evenly distributed and equally wide stator teeth (313), and winding slots (314) are formed between adjacent stator teeth. The winding slots have stator slot openings (315) facing the third air gap (330). The number of magnetic field pole pairs generated by the winding is P1, the number of stator teeth is P2, the number of second rotor pole pairs is P3, and P1+P3=P2.

29. The mid-mounted motor for a power-assisted bicycle according to claim 28, characterized in that: The stator tooth (313) has a stator shoe (316) extending toward the stator slot (315) near the third air gap (330).

30. The mid-mounted motor for a power-assisted bicycle according to any one of claims 15-23, characterized in that: The first rotor (420) and the second rotor (320) are both configured on the same cylindrical rotor shaft (700), which is sleeved on the radial outside of the torque assembly (200).

31. The mid-mounted motor for a power-assisted bicycle according to any one of claims 15-23, characterized in that: The motor part (300) and the magnetic drive reduction device (400) are axially connected in series on the same axis.

32. The mid-mounted motor for a power-assisted bicycle according to any one of claims 15-23, characterized in that: The motor part (300) overlaps with the magnetic drive reduction device (400) in the axial part, and the motor part is placed inside the reduction device.

33. The mid-mounted motor for a power-assisted bicycle according to any one of claims 15-23, characterized in that: The motor part (300) and the magnetic drive reduction device (400) overlap axially, and the entire motor is placed inside the reduction device.

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