Middle motor

Abstract

The utility model discloses a middle motor, which comprises a shell, a motor assembly and a transmission assembly, the motor assembly comprises a driving shaft, and the output end of the driving shaft is provided with a primary driving wheel; the transmission assembly comprises a first-stage driven wheel, a transmission shaft, an isolator and at least one bearing, the outer side of the first-stage driven wheel is meshed with a gear of the first-stage driving wheel, the first-stage driven wheel is arranged on the outer ring of the isolator in a sleeving mode, the inner ring of the isolator is connected with the transmission shaft in a matched mode, the outer ring of the bearing is connected with the shell in a matched mode, and the outer ring of the bearing is connected with the first-stage driven wheel in a matched mode. At least one of at least one bearing in the transmission assembly is arranged on the outer ring of the isolator in a sleeving mode, and the first-stage driven wheels are arranged at intervals. The centrally-mounted motor provided by the utility model is light in weight, small in axial space and compact in structure, and meets the requirement of small size of the motor.

Description

Technical Field

[0001] The utility model relates to the field of mid-mounted motors, and particularly relates to a mid-mounted motor. Background Art

[0002] A mid-mounted motor refers to a drive motor installed in the middle position of an electric assist bicycle, that is, the motor at the pedal position; the motor is connected to the body and transmits power through a chain to the rear wheel. At the same time, pedals are installed on both sides of the motor. In the case of power failure of the motor, the user can ride manually through the pedals.

[0003] The mid-mounted motor includes a motor assembly, a transmission assembly, and a central shaft assembly. The central shaft assembly is connected to the rear wheel through a chain, and the transmission assembly can transmit the driving force of the motor assembly to the central shaft assembly. In the existing transmission assembly, the support points on both sides of the gear are usually arranged on both sides of the central shaft, and the two side bearings are directly matched with the shaft to play a role in rotating support on both sides of the gear. Although this arrangement has a simple structure and good processability, it will increase the axial distance of the transmission assembly and thus increase the overall machine mass, and it cannot meet the requirement of the compact motor for a small and compact design. Summary of the Utility Model

[0004] In view of the deficiencies of the prior art, the utility model provides a mid-mounted motor, which has a light mass, a small axial space for two-stage transmission, a compact structure, and meets the requirement of the motor for being small and compact.

[0005] The utility model is realized through the following technical solutions:

[0006] A mid-mounted motor, comprising:

[0007] A housing;

[0008] A motor assembly, including a drive shaft, and a primary drive wheel is provided at the output end of the drive shaft;

[0009] A transmission assembly, including a primary driven wheel, a transmission shaft, a one-way clutch, and at least one bearing. The outer side of the primary driven wheel is in gear engagement with the primary drive wheel. The primary driven wheel is sleeved on the outer ring of the one-way clutch. The inner ring of the one-way clutch is connected to the transmission shaft. The outer ring of the bearing is connected to the housing. At least one of the at least one bearing in the transmission assembly is sleeved on the outer ring of the one-way clutch and the primary driven wheel is spaced apart. The transmission shaft includes an output tooth portion;

[0010] A central shaft transmission mechanism, which is directly or indirectly connected to the output tooth portion in transmission. The central shaft transmission mechanism includes a central shaft and a torque sensor. The two ends of the central shaft are respectively connected to a crank and a pedal, and can receive power input through the cranks at both ends. The torque sensor is provided on the central shaft.

[0011] Further, the central shaft transmission mechanism further includes a secondary driven wheel set, and the secondary driven wheel set meshes with the output tooth portion gear.

[0012] Further, the transmission assembly further includes a bushing, the bushing is fixedly sleeved on the transmission shaft, and the inner side of the one-way clutch is sleeved on the bushing.

[0013] Further, a retaining edge is convexly provided on the outer peripheral surface of the bushing, and the retaining edge is located between the one-way clutch and the output tooth portion of the transmission shaft.

[0014] Further, a first strengthening structure is provided at the outer peripheral surface of the transmission shaft corresponding to the bushing, and the first strengthening structure protrudes or depresses from the outer peripheral surface of the transmission shaft.

[0015] Further, the first strengthening structure is a strengthening tooth, knurling or spline arranged around the outer periphery of the transmission shaft.

[0016] Further, the primary driven wheel includes a central insert and an outer ring tooth portion, the center of the central insert has a shaft hole, the outer ring tooth portion is connected to the outer circumference of the central insert and is coaxially arranged, the width of the outer ring tooth portion in the axial direction is greater than the width of the central insert in the axial direction, and both ends of the outer ring tooth portion in the axial direction exceed the central insert; the central insert is made of a metal material, and the outer ring tooth portion is made of a non-metal material.

[0017] Further, a second strengthening structure is provided on the outer peripheral surface of the central insert; the second strengthening structure protrudes or depresses from the outer peripheral surface of the central insert.

[0018] Further, the second strengthening structure is a strengthening tooth, knurling or spline arranged around the outer circumference of the central insert.

[0019] Further, the strengthening tooth is axially divided into at least three segments.

[0020] Further, the tooth top surface of the strengthening tooth is an arc surface or a surface with an obtuse angle.

[0021] Further, the number of the splines is not less than 4, and the spline module is not less than 0.25.

[0022] Further, the outer ring tooth portion is integrally formed by injection molding.

[0023] Further, the transmission shaft includes an input end, an output tooth portion, and a support shaft. The output tooth portion is located between the input end and the support shaft. The first strengthening structure is formed on the outer peripheral surface of the input end. The input end is connected to the shaft sleeve through the first strengthening structure arranged on the surface of the input end. The diameter of the support shaft is smaller than the diameters of the output tooth portion and the input end.

[0024] Further, the shaft sleeve fits against the end face of the output tooth portion.

[0025] Further, a needle roller bearing is sleeved on the outside of the support shaft, and the outer diameter of the needle roller bearing is smaller than the tip circle diameter of the output tooth portion.

[0026] Compared with the prior art, the advantages of the present utility model are as follows:

[0027] 1. By press-fitting the bearing on the one-way clutch, the axial part where the one-way clutch and the bearing overlap is saved, which can greatly reduce the volume and mass, shorten the axial space, achieve a small axial dimension of the motor, and thus meet the requirement of a compact motor.

[0028] 2. By providing a shaft sleeve and fixedly sleeving the shaft sleeve on the transmission shaft, the space waste of the part being hobbed and knurled is avoided through a split design, reducing the volume and weight. It not only meets the requirement of high hardness at the mating position of the one-way clutch but also meets the requirement of toughness at the core of the tooth shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of a mid-mounted motor according to an embodiment of the present utility model;

[0030] Figure 2 is a partial structural schematic diagram of the mid-mounted motor;

[0031] Figure 3 is a schematic structural diagram of the motor assembly;

[0032] Figure 4 is a schematic structural diagram of the rotor core;

[0033] Figure 5 is a schematic structural diagram of the core punching sheet;

[0034] Figure 6 is a schematic structural diagram of the transmission assembly;

[0035] Figure 7 is a cross-sectional view of the transmission assembly;

[0036] Figure 8 is an exploded view of the transmission assembly;

[0037] Figure 9 is an enlarged partial structural diagram of the transmission assembly;

[0038] Figure 10 Front view of the mid-mounted motor;

[0039] Figure 11 is Figure 10 Sectional view along A-A in

[0040] 100, housing; 200, motor assembly; 210, drive shaft; 211, primary drive gear; 220, rotor; 250, iron core punching; 252, shaft hole; 251, notch; 253, iron core yoke; 254, iron core teeth; 255, magnet mounting groove; 256, pole shoe; 257, magnetic isolation strip; 258, round hole; 259, support block; 230, stator; 240, shaft installation hole; 300, transmission assembly; 310, primary driven gear; 311, central insert; 313, reinforcing teeth; 312, outer ring teeth; 320, transmission shaft; 322, input end; 321, spline; 323, output teeth; 324, support shaft; 325, needle roller bearing; 330, one-way clutch; 340, bearing; 350, shaft sleeve; 351, flange; 400, central shaft transmission mechanism; 410, secondary driven gear set; 420, central shaft; 430, torque sensor; 440, ratchet ring; 450, pawl; 460, controller; 470, first bearing; 471, second bearing; 472, third bearing; 473, TC skeleton seal. Detailed implementation manners

[0041] The technical solutions of the utility model will be further described in detail and non-limitingly below in conjunction with the preferred embodiments and their accompanying drawings. In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present utility model, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present utility model and should not be construed as a limitation of the present utility model.

[0042] As Figure 1 and Figure 2As shown in the figure, a mid-mounted motor according to an embodiment of the present invention includes a housing 100, a motor assembly 200, a transmission assembly 300, and a central shaft transmission mechanism 400. The motor assembly 200, the transmission assembly 300, and the central shaft transmission mechanism 400 are integrated inside the housing 100. The central shaft transmission mechanism 400 has a central shaft 420. Both ends of the central shaft 420 pass through the housing 100 and are respectively connected to a crank and a foot pedal, and can receive power input through the crank structures at both ends.

[0043] As Figures 3 - 5 shown in the figure, the motor assembly 200 includes a drive shaft 210, a rotor 220, and a stator 230. The drive shaft 210 is in interference fit with the rotor 220, and a first-stage driving wheel 211 is provided at the output end of the drive shaft 210. The stator 230 is disposed outside the rotor 220.

[0044] The rotor 220 has a rotor core. The rotor core includes multiple groups of core punching sheets. Each group of core punching sheets includes at least one core punching sheet 250. The number of core poles of the core punching sheet 250 is N (N is an even number greater than 2). There are M notches 251 in the shaft hole 252 of the core punching sheet 250, and M is not an integer multiple of N. After multiple groups of core punching sheets 250 are stacked and formed into a rotor core, the projections of the notches 251 of at least one group of core punching sheets on the plane where any one of the core punching sheets 250 is located do not overlap (or are at least partially staggered) with the notches 251 of other groups of core punching sheets. In this embodiment, by providing the notches 251 in the shaft hole 252 of the core punching sheet 250, the notches 251 can be axially staggered along the axis of the rotating shaft and connected to the rotating shaft in an interference fit manner after being stacked and formed, so that the notch defects caused by process reasons can be evenly distributed in the circumferential direction of the rotating shaft, thereby avoiding the concentration of defective notches. The rotor core provided by the present invention reduces or eliminates the jumping problem of the rotating shaft after being pressed into the rotor core due to the notch by providing the notches 251 in the shaft hole 252 and staggering the notches 251 during the stacking and forming process.

[0045] The angular difference between two adjacent groups of iron core punching sheets 250 is K (i.e., after one group of adjacent iron core punching sheets 250 rotates by an angle K, they are stacked again), where K = 360*n / N, and n is a natural number less than N; the angular difference K ≠ 360*m / M (to avoid the coincidence of different notches 251 after rotating by the angle K), and m is a natural number less than M, so that the notches 25l of multiple groups of iron core punching sheets 250 are arranged in a spiral shape on the shaft mounting hole 240 of the rotor iron core. The spiral shape includes at least 1 circumference, so that the notches 251 can be evenly distributed on the circumference of the entire drive shaft 210, and the notches 251 are evenly stressed in all directions. Further, the spiral shape is an integer number of circumferences, that is, it can be 1, 2 or more circumferences, so that the notches 251 can be evenly distributed on the circumference of the entire rotating shaft, and the notches 25l are evenly stressed in all directions. In addition, the notch 251 is triangular, arc-shaped, semi-circular, rectangular or trapezoidal, and the notch 251 can also be any combination of the above shapes, or the notch 251 can also be other special-shaped shapes not exemplified. In order to reduce the stress concentration caused by the notch 25l, a circular arc transition structure can be designed for the notch 251.

[0046] Generally, the number M of notches 251 should be much smaller than the number of iron core poles N to reduce the number of openings of the notches 25l and ensure a sufficiently large contact area between the iron core punching sheet 250 and the drive shaft 210.

[0047] Optionally, the number M of notches 25l can be multiple, and the M notches 251 are evenly distributed on the edge of the shaft hole 252, so that when the iron core punching sheet 250 is in interference fit with the drive shaft 210, the contact area between each position of the shaft hole 252 of the iron core punching sheet 250 and the drive shaft 210 is equal, and the stresses in all directions are also equal.

[0048] The iron core punching sheet 250 includes an iron core yoke 253 and iron core teeth 254 arranged in a circumferential array around the iron core yoke 253. At both ends of the outer edge of each iron core tooth 254, pole shoes 256 extending to both sides are provided, and a magnet mounting groove 255 is formed between two adjacent iron core teeth 254; wherein, the iron core teeth 254 are fan-shaped structures with a radius r1 smaller than the radius R of the iron core punching sheet 250. The centers of the fan-shaped structures of all the iron core teeth 254 are on the same circle with the axis of the rotor iron core as the center, and its radius is r2, and R = rl + r2 is satisfied. Specifically, the arrangement direction of each fan-shaped structure points outward along the connection line between the center of the iron core punching sheet 250 and the center of the iron core tooth 254; and the midpoint of the arc of the fan-shaped structure is located on the outer circle of the iron core punching sheet 250 at the same time. Designing the iron core teeth 254 of the iron core punching sheet 250 as an eccentric circle structure relative to the center of the entire iron core punching sheet can ensure that the waveform is closer to a sine wave and reduce harmonics.

[0049] The iron core tooth part 254 is connected to the iron core yoke part 253 through a magnetic isolation strip 257. The width of the magnetic isolation strip 257 is smaller than the minimum width of the iron core tooth part 254, and the magnetic isolation strip 257 can effectively reduce magnetic leakage.

[0050] Round holes 258 are provided on the fan-shaped surface of the iron core tooth part 254. The distances from the round holes 258 to the three sides of the fan-shaped surface are equal. Through the structural design of the round holes 258, the magnetic density can be ensured to be uniform.

[0051] A support block 259 is also provided on the iron core yoke part 253 between two adjacent magnetic isolation strips 257 to position the short side of the permanent magnet and reduce magnetic leakage. The support block 259 can position and fix the permanent magnet. Specifically, after the permanent magnet is pressed into the permanent magnet installation groove 255, the support block 259 deforms to a certain extent and then abuts against the side surface of the permanent magnet, making the permanent magnet and the permanent magnet installation groove 255 form an interference fit in the radial direction. The permanent magnet tightly abuts against the convex edge or limiting structure on the outside of the permanent magnet installation groove 255, effectively reducing the change in unbalance caused by the displacement of the permanent magnet and the resulting vibration noise.

[0052] As Figures 6 - 9 shown, the transmission component 300 includes a first-stage driven wheel 310, a transmission shaft 320, a one-way clutch 330, and at least one bearing 340. The outside of the first-stage driven wheel 310 is in gear engagement with the first-stage driving wheel 211. The first-stage driven wheel 310 is sleeved on the outer ring of the one-way clutch 330. The inner ring of the one-way clutch 330 is connected to the transmission shaft 320. The outer ring of the bearing 340 is connected to the housing 100. At least one of the at least one bearing 340 in the transmission component 300 is sleeved on the outer ring of the one-way clutch 330 and the first-stage driven wheel 310 is spaced apart.

[0053] In this embodiment, the bearing 340 adopts a deep groove ball bearing and is press-fitted on the one-way clutch 330, saving the axial part where the one-way clutch 330 and the bearing 340 overlap. The volume and mass can be greatly reduced, the axial space can be shortened, the axial dimension of the motor can be made small, and thus the compact requirement of the motor can be achieved.

[0054] The transmission assembly 300 further includes a bushing 350. The bushing 350 is fixedly sleeved on the transmission shaft 320, and the inner side of the one-way clutch 330 is sleeved on the bushing 350. The outer ring of the bushing 350 has a higher surface finish and no damage, and rotates more smoothly when cooperating with the one-way clutch 330. Since there is a lot of waste of the available axial space during hobbing of the output tooth portion 323 on the transmission shaft 320, the one-way clutch 330 cannot be directly fitted at the position closest to the output tooth portion 323. In order to make full use of this space and shorten the axial dimension, a split structure is adopted. By providing a bushing 350 on the transmission shaft 320, the inner side of the one-way clutch 330 is sleeved on the bushing 350. A retaining edge 315 is convexly provided on the outer peripheral surface of the bushing 350, and the retaining edge 315 is located between the one-way clutch 330 and the output tooth portion 323 of the transmission shaft 320. It meets the requirement of high hardness at the fitting position of the one-way clutch 330 and also meets the requirement of toughness of the core of the transmission shaft 320. For the fitting method of the transmission shaft 320 and the bushing 350, only the hardness of the bushing 350 needs to be heat-treated, and the hardness of the transmission shaft 320 ensures its toughness.

[0055] Specifically, a first strengthening structure is provided at the outer peripheral surface of the transmission shaft 320 corresponding to the outer peripheral surface of the bushing 350. The first strengthening structure protrudes or recesses from the outer peripheral surface of the transmission shaft 320. By designing the first strengthening structure, the connection area between the transmission shaft 320 and the bushing 350 can be effectively increased, so that the combination between the transmission shaft 320 and the bushing 350 is more stable, and the overall shape can also be kept unchanged during the transmission process; especially when the length of the transmission shaft 320 is reduced, the problem of the reduced connection area can be compensated by designing the first strengthening structure.

[0056] Among them, the first strengthening structure is a strengthening tooth, knurling or spline 321 arranged around the outer periphery of the transmission shaft 320. In this embodiment, the spline 321 structure is adopted.

[0057] The first-level driven gear 310 includes a central insert 311 and an outer ring tooth part 312. The center of the central insert 311 has a shaft hole. The outer ring tooth part 312 is connected to the outer circumference of the central insert 311 and is coaxially arranged. The width of the outer ring tooth part 312 in the axial direction is greater than the width of the central insert 311 in the axial direction, and both ends of the outer ring tooth part 312 in the axial direction exceed the central insert 311. The central insert 311 is made of a metal material, and the outer ring tooth part 312 is made of a non-metal material. In the transmission system provided in this embodiment, since the drive shaft 210 directly drives the first-level driven gear 310 and the rotational speed of the drive shaft 210 is high, if the first-level driven gear 310 made of an integral metal material is used, the moment of inertia is relatively large, resulting in energy loss. However, using a first-level driven gear 310 made of a non-metal material faces the problems of relatively large contact surface stress and insufficient support strength to meet the transmission requirements. Therefore, in this embodiment, the central insert 311 made of a metal material and the outer ring tooth part 312 made of a non-metal material are adopted, and the width of the outer ring tooth part 312 is greater than that of the central insert 311. On the one hand, it ensures a larger contact area between the outer ring tooth part 312 and the drive shaft 210, reducing the contact stress on the outer ring tooth part 312. On the other hand, it also makes the overall moment of inertia of the central insert 311 and the outer ring tooth part 312 lower, reducing the energy loss during the transmission process. On the third hand, since the central insert 311 made of a metal material has a smaller size, it can meet the requirements of transmission torque.

[0058] A second strengthening structure is provided on the outer circumferential surface of the central insert 311, and the second strengthening structure protrudes or recesses from the surface of the outer circumference of the central insert 311. By designing the second strengthening structure, the connection area between the central insert 311 and the outer ring tooth part 312 can be effectively increased, so that the combination between the central insert 311 and the outer ring tooth part 312 is more stable, and the overall shape can also be kept unchanged during the transmission process. Especially when the width of the central insert 311 is reduced, the problem of reduced connection area can be compensated by designing the second strengthening structure.

[0059] In this embodiment, the second strengthening structure is a strengthening tooth 313, knurling or spline arranged around the outer circumference of the central insert 311.

[0060] In this embodiment, the strengthening tooth 313 is axially divided into at least three segments. Such a design can not only further increase the connection area between the outer ring tooth part 312 and the central insert 311, but also overcome the axial stress during the transmission process, maintaining the structural stability of the central insert 311 and the outer ring tooth part 312 during the transmission process.

[0061] The tooth top surface of the strengthening tooth 313 is an arc surface or a surface with an obtuse angle. In this embodiment, the protruding top cannot be made into a sharp angle, and the width of the top is not less than 0.2 mm to avoid stress concentration during injection molding, and when bearing a large torque, the sharp angle end breaks.

[0062] In this embodiment, when splines are used between the central insert 311 and the outer ring tooth part 312, the number of splines is not less than 4, and the spline module is not less than 0.25.

[0063] In this embodiment, the outer ring tooth part 312 is integrally formed by injection molding on the outer circumference of the central insert 311, which can make the connection between the central insert 311 and the outer ring tooth part 312 tighter, so that it is not easy to deform during the transmission process.

[0064] The transmission shaft 320 includes an input end 322, an output tooth part 323 and a support shaft 324. The output tooth part 323 is located between the input end 322 and the support shaft 324. The first strengthening structure is formed on the outer peripheral surface of the input end 322. The input end 322 and the shaft sleeve 350 are connected through the first strengthening structure arranged on the surface of the input end 322. The diameter of the support shaft 324 is smaller than the diameters of the output tooth part 323 and the input end 322. The shaft sleeve 350 fits against the end face of the output tooth part 323, and no gap needs to be left between the shaft sleeve 350 and the output tooth part 323, which can shorten the axial length of the transmission shaft 320. The middle shaft transmission mechanism 400 is directly or indirectly drivingly connected to the output tooth part (323)

[0065] A needle roller bearing 325 is sleeved on the outside of the support shaft 324, and the outer diameter of the needle roller bearing 325 is smaller than the pitch circle diameter of the output tooth part 323.

[0066] Such as Figure 10 And Figure 11As shown in the figure, the central shaft drive mechanism 400 further includes a secondary driven wheel set 410, a central shaft 420, a torque sensor 430, a ratchet ring 440, a pawl 450, and a controller 460. The secondary driven wheel set 410 is in gear engagement with the output tooth portion 323. Both ends of the central shaft 420 pass through the housing 100 and are successively connected with a crank and a pedal, and can receive power input through the cranks at both ends. The torque sensor 430 and the pawl 450 are arranged on the central shaft 420, and the ratchet ring 440 can engage with the pawl 450. A first bearing 470 and a second bearing 471 are arranged between the secondary driven wheel set 410 and the housing 100, and a third bearing 472 and a TC skeleton seal ring 473 are arranged between the secondary driven wheel set 410 and the central shaft 420. Working state of human riding and pedaling: The pedal crank is connected to the central shaft 420, and the bicycle chain sprocket is connected to the secondary driven wheel set 410. After a person steps on the pedal, the central shaft 420 is forced to rotate, and the torque sensor 430 on the central shaft 420 is forced through the engaged ratchet ring 440 and pawl 450, so that the torque sensor 430 generates an induction signal and transmits it to the controller 460, causing the controller 460 to drive the motor and then causing the first-stage driving wheel 211 to operate. The first-stage driving wheel 211 drives the first-stage driven wheel 310 to rotate. With the aid of the one-way clutch 330, the motor torque is transmitted to the output tooth portion 323 on the transmission shaft 320. The output tooth portion 323 then drives the secondary driven wheel set 410 to operate and further transmits the torque to the bicycle sprocket. The sprocket transmits the torque to the drive sprocket of the electric bicycle through the chain, driving the electric bicycle forward. Working state of the twist grip: After the twist grip rotates, it transmits a signal to the controller 460. The controller 460 drives the motor and then causes the first-stage driving wheel 211 to operate. The first-stage driving wheel 211 drives the first-stage driven wheel 310 to rotate. With the aid of the one-way clutch 330, the motor torque is transmitted to the output tooth portion 323 on the transmission shaft 320. The output tooth portion 323 then drives the secondary driven wheel set 410 to operate and further transmits the torque to the bicycle sprocket. The sprocket transmits the torque to the drive sprocket of the electric bicycle through the chain, driving the electric bicycle forward. The torque generated by the motor passes through the first-stage driving wheel 211, the first-stage driven wheel 310, the output tooth portion 323, and the secondary driven wheel set 410 on the drive shaft 210 in sequence, causing the secondary driven wheel set 410 to drive the ratchet ring 440 to operate, disengaging the pawl 450 from the ratchet ring 440 and thus disengaging from the central shaft 420. At this time, the central shaft 420, the crank, and the pedal do not rotate together.

[0067] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. A mid-mounted motor, characterized in that, Comprising: A housing (100); A motor assembly (200) including a drive shaft (210), with a primary driving pulley (211) provided at the output end of the drive shaft (210); A transmission assembly (300) including a primary driven pulley (310), a transmission shaft (320), a one-way clutch (330), and at least one bearing (340). The outer side of the primary driven pulley (310) is in gear engagement with the primary driving pulley (211). The primary driven pulley (310) is sleeved on the outer ring of the one-way clutch (330). The inner ring of the one-way clutch (330) is mated with the transmission shaft (320). The outer ring of the bearing (340) is mated with the housing (100). At least one of the at least one bearing (340) in the transmission assembly (300) is sleeved on the outer ring of the one-way clutch (330) and is spaced from the primary driven pulley (310). The transmission shaft (320) includes an output tooth portion (323); A central shaft transmission mechanism (400) is directly or indirectly drivingly connected to the output tooth portion (323). The central shaft transmission mechanism (400) includes a central shaft (420) and a torque sensor (430). The two ends of the central shaft (420) pass through the housing (100) and are sequentially connected with cranks and pedals, and can receive power input through the cranks at both ends. The torque sensor (430) is provided on the central shaft (420).

2. The mid-mounted motor according to claim 1, characterized in that, The central shaft transmission mechanism (400) further includes a secondary driven pulley group (410), and the secondary driven pulley group (410) is in gear engagement with the output tooth portion (323).

3. The mid-mounted motor according to claim 1, characterized in that The transmission assembly (300) further includes a bushing (350), and the bushing (350) is fixedly sleeved on the transmission shaft (320). The inner side of the one-way clutch (330) is sleeved on the bushing (350).

4. The mid-mounted motor according to claim 3, wherein A rib (315) is convexly provided on the outer peripheral surface of the bushing (350), and the rib (315) is located between the one-way clutch (330) and the output tooth portion (323) of the transmission shaft (320).

5. The mid-mounted motor according to claim 4, characterized in that, A first strengthening structure is provided at the outer peripheral surface of the transmission shaft (320) corresponding to the outer peripheral surface of the bushing (350), and the first strengthening structure protrudes or depresses from the outer peripheral surface of the transmission shaft (320).

6. The mid-mounted motor according to claim 5, characterized in that, The first strengthening structure is strengthening teeth, knurling, or splines (321) arranged around the outer periphery of the transmission shaft (320).

7. The mid-mounted motor according to claim 1, wherein, The primary driven pulley (310) includes a central insert (311) and an outer ring tooth portion (312). The center of the central insert (311) has a shaft hole. The outer ring tooth portion (312) is connected to the outer circumference of the central insert (311) and is coaxially arranged. The width of the outer ring tooth portion (312) in the axial direction is greater than the width of the central insert (311) in the axial direction, and both ends of the outer ring tooth portion (312) in the axial direction exceed the central insert (311); the central insert (311) is made of a metal material, and the outer ring tooth portion (312) is made of a non-metal material.

8. The mid-mounted motor according to claim 7, wherein The outer circumferential surface of the central insert (311) is provided with a second strengthening structure; the second strengthening structure protrudes or recesses from the surface of the outer circumference of the central insert (311).

9. The mid-mounted motor according to claim 8, wherein, The second strengthening structure is strengthening teeth (313), knurling or splines arranged around the outer circumference of the central insert (311).

10. The mid-mounted motor according to claim 9, characterized in that, The strengthening teeth (313) are axially segmented into at least three segments.

11. The mid-mounted motor according to claim 9, wherein, The tooth top surface of the strengthening teeth (313) is an arc surface or a surface with an obtuse angle.

12. The mid-mounted motor according to claim 9, characterized in that, The number of the splines is not less than 4, and the module of the splines is not less than 0.

25.

13. The mid-mounted motor according to claim 7, wherein, The outer ring tooth part (312) is integrally formed by injection molding.

14. The mid-mounted motor according to claim 5, characterized in that, The transmission shaft (320) includes an input end (322), an output tooth part (323) and a support shaft (324). The output tooth part (323) is located between the input end (322) and the support shaft (324). The first strengthening structure is formed on the outer circumferential surface of the input end (322). The input end (322) is connected to the shaft sleeve (350) through the first strengthening structure arranged on the surface of the input end (322). The diameter of the support shaft (324) is smaller than the diameters of the output tooth part (323) and the input end (322).

15. The mid-mounted motor according to claim 14, characterized in that, The shaft sleeve (350) is attached to the end face of the output tooth part (323).

16. The mid-mounted motor according to claim 14, characterized in that, A needle roller bearing (325) is sleeved outside the support shaft (324), and the outer diameter of the needle roller bearing (325) is smaller than the pitch circle diameter of the top of the teeth of the output tooth part (323).

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