CN113074232A - Harmonic transmission system of electric bicycle - Google Patents

Abstract

The invention provides an electric bicycle harmonic transmission system arranged in a five-way pipe, which comprises a shell, a motor stator, a motor rotor, a bearing, a first one-way clutch, an output shaft, a flexible bearing, a flexible wheel, a crossed roller bearing, a connecting piece, a second one-way clutch and a torsion sensor. The invention can reduce the weight, the volume and the noise of the harmonic transmission system of the electric moped, simultaneously improve the reduction ratio of the harmonic transmission system of the electric moped, improve the transmission precision, further improve the battery endurance, improve the riding comfort and improve the aesthetic design of appearance.

Description

Harmonic transmission system of electric bicycle

Technical Field

The invention relates to a harmonic transmission system of an electric moped, in particular to a transmission system of an electric moped with a harmonic reducer.

Background

Please refer to fig. 7, which is a schematic cross-sectional view of an embodiment of a planetary gear transmission device of a prior art electric bicycle. The planetary gear transmission 9 includes an electric motor 92, a hollow connecting shaft 93, a brake device 98, a hollow gear 94, a center gear 96, three planetary gears 95, and a planetary gear carrier 99. Please refer to fig. 8, which is a partial enlarged cross-sectional view of the prior art embodiment of fig. 7. The ring gear 94 has an inner gear and an outer gear. The center wheel 96 has an outer gear. The three planetary gears 95 each have an external gear. The three planetary gears 95 mesh with an internal gear of the ring gear 94 and an external gear of the sun gear 96, respectively. The carrier 99 is connected to three planetary gears 95, respectively. The outer gear of the ring gear 94 engages with a link of a chain 97 of an electric bicycle. A middle shaft 91 of the electric moped passes through the center of the hollow connecting shaft 93 and is fixedly connected with the planet carrier 99. The hollow connecting shaft 93 is fixedly connected to the electric motor 92 and also fixedly connected to the center wheel 96. In the prior art, the planetary gear transmission device 9 is mainly used and has the defects of low speed reduction ratio, heavy weight, large volume, high noise, low transmission precision and the like. Because of the problems of low speed reduction ratio, heavy weight and the like, the required power of the electric motor is high, and the endurance of the battery is influenced. In addition, the noise and the transmission accuracy are low, which affects the riding comfort of the user. Moreover, the larger volume will affect the aesthetic appearance of the moped.

Disclosure of Invention

In view of the above, the present inventors have developed a simple assembly design, which can avoid the above disadvantages, is convenient to install, and has the advantage of low cost, so as to take account of both flexibility and economy.

In order to solve the above-mentioned problems and achieve the desired effect, the present invention provides a harmonic transmission system of an electric bicycle, which is disposed in a five-way pipe of a frame of the electric bicycle, and includes a housing, a motor stator, a motor rotor, at least one second bearing, a first one-way clutch, a motor output shaft, at least one first bearing, a flexible wheel, a crossed roller bearing, a connecting member, a second one-way clutch, and a torque sensor. The motor stator is fixed on the shell. The motor stator has an inner race. The motor rotor is accommodated in the inner ring of the motor stator. The motor rotor has an inner race. Each of the at least one second bearings has an inner race. The second one-way clutch and the at least one second bearing are accommodated in the inner race of the motor rotor. The second one-way clutch has an inner race. The motor output shaft is provided with an inner ring. A first end of the motor output shaft is accommodated in the inner ring of the second one-way clutch and the inner ring of each at least one second bearing. A second end of the motor output shaft is provided with an elliptical cam. The motor rotor, the motor stator and the motor output shaft form an electric motor. At least one first bearing is received within the inner race of the first end of the motor output shaft. Each of the at least one first bearing has an inner race. The compliant bearing has an inner race. The flexible bearing is used for accommodating the elliptical cam at the second end of the motor output shaft, so that the flexible bearing is deformed into an elliptical shape. Wherein the elliptical cam at the second end of the motor output shaft and the flexible bearing form a wave generator. The flexible gear comprises a flexible gear body and a flexible gear extension part. The flexible gear body is provided with an inner ring. A first end of the flexible gear body is provided with an external gear. The wave generator is accommodated in the inner ring of the first end of the flexible gear body, so that the first end of the flexible gear body is deformed into an elliptical shape. The flexible gear extension part is connected with a second end of the flexible gear body. The flexible gear extension part extends outwards from the second end of the flexible gear body, so that the flexible gear forms a hat shape. The crossed roller bearing comprises a crossed roller bearing inner ring, a crossed roller bearing outer ring and a plurality of crossed rollers. Wherein a first end of the inner ring of the crossed roller bearing is fixed on the shell. The first end of the crossed roller bearing inner ring is provided with an inner gear which is meshed with the outer gear at the first end of the flexible gear body. A second end of the crossed roller bearing inner ring has an inner race and an outer groove. The inner ring of the second end of the inner ring of the crossed roller bearing is used for accommodating the second end of the flexible gear body. The crossed roller bearing outer ring has an inner race and an inner groove. The inner race of the outer race of the crossed roller bearing is adapted to receive the second end of the inner race of the crossed roller bearing. The inner groove of the outer ring of the crossed roller bearing is positioned corresponding to the outer groove of the inner ring of the crossed roller bearing, so that a crossed roller accommodating space is formed between the inner groove of the outer ring of the crossed roller bearing and the outer groove of the inner ring of the crossed roller bearing. The plurality of crossed rollers are accommodated in the crossed roller accommodating space. The connecting piece is provided with a first end and a second end. The flexible gear extension part of the flexible gear is respectively connected with the outer ring of the crossed roller bearing and the first end of the connecting piece. The second end of the connecting piece is provided with an inner ring. The first one-way clutch is accommodated in the inner ring of the second end of the connecting piece. The first one-way clutch has an inner race. The torque sensor has an inner ring. A first end of the torque sensor is accommodated in the inner ring of the first one-way clutch. The first end of the torsion sensor is connected with a chain plate of the electric moped. The inner ring of each at least one first bearing and the inner ring of the torque sensor are used for accommodating a middle shaft of the electric moped. The second end of the torque sensor is connected with the middle shaft of the electric moped.

In an embodiment, the harmonic drive system of the electric bicycle comprises at least one second bearing selected from the group consisting of: a ball bearing and a needle bearing.

In an embodiment, the second end of the torque sensor is accommodated in the inner ring of the second end of the output shaft of the motor.

In an embodiment, the harmonic transmission system of the electric bicycle further includes a third bearing, wherein the second end of the motor output shaft further includes an extension portion, the second end of the connecting member further includes an extension portion, the extension portion of the second end of the connecting member has an inner ring for accommodating the third bearing, and the third bearing has an inner ring for accommodating the extension portion of the second end of the motor output shaft.

In an embodiment, the harmonic drive system of the electric bicycle comprises a third bearing selected from at least one of the following groups: a ball bearing and a needle bearing.

In an embodiment, the harmonic transmission system of the electric bicycle further includes a fourth bearing, wherein the fourth bearing has an inner ring, the first end of the motor output shaft is accommodated in the inner ring of the fourth bearing and the inner ring of the motor rotor, and the fourth bearing is located between the motor rotor and the second end of the motor output shaft.

In an embodiment, the harmonic drive system of the electric bicycle comprises a fourth bearing selected from at least one of the following groups: a ball bearing and a needle bearing.

In an embodiment of the harmonic transmission system of the electric bicycle, the harmonic transmission system further includes a fifth bearing, the first end of the motor output shaft further includes an extension portion, wherein the fifth bearing has an inner ring, and the extension portion of the first end of the motor output shaft is accommodated in the inner ring of the fifth bearing.

In an embodiment, the harmonic transmission system of the electric bicycle further includes a retaining ring for the first shaft, wherein the fifth bearing has a fifth bearing inner ring, the first end of the motor output shaft further includes a fixing portion, and the retaining ring for the first shaft and the fixing portion of the first end of the motor output shaft are used to fix the fifth bearing inner ring of the fifth bearing on the motor output shaft.

In an embodiment, the harmonic drive system of the electric bicycle comprises a fifth bearing selected from at least one of the following groups: a ball bearing and a needle bearing.

In an embodiment, the harmonic transmission system of the electric bicycle comprises at least one first bearing selected from the group consisting of: a ball bearing and a needle bearing.

In an embodiment of the harmonic transmission system of the electric bicycle, the ball bearing is a deep groove ball bearing.

In an embodiment, the harmonic transmission system of the electric bicycle further includes a retaining ring for the second shaft, and the at least one first bearing has an inner ring, and the retaining ring for the second shaft is used to fix the inner ring of the at least one first bearing to the center shaft of the electric bicycle.

In an embodiment, the electric motor of the harmonic drive system of the electric bicycle comprises one of the following components: a brushless DC motor and a brushed DC motor.

In an embodiment, the harmonic transmission system of the electric bicycle further includes a battery, wherein the battery is electrically connected to the electric motor.

In an embodiment of the harmonic transmission system of the electric bicycle, the battery is a rechargeable battery.

In an embodiment of the harmonic transmission system of the electric bicycle, the battery is disposed in a center tube or an inclined tube of the frame.

In an embodiment of the harmonic transmission system of the electric bicycle, the first end of the inner ring of the crossed roller bearing, the flexible gear and the wave generator form a harmonic reducer, and a rotation shaft of the harmonic reducer coincides with a rotation shaft of the motor output shaft.

In an embodiment, in the harmonic transmission system of the electric bicycle, the rotating shaft of the harmonic reducer is overlapped with an input rotating shaft of the torque sensor.

In an embodiment of the harmonic transmission system of the electric bicycle, the first end of the inner ring of the crossed roller bearing, the flexible gear and the wave generator form a harmonic reducer, and a rotation shaft of the harmonic reducer coincides with an input rotation shaft of the torque sensor.

The invention has the advantages that the weight, the volume and the noise of the harmonic transmission system of the electric moped can be reduced, the reduction ratio of the harmonic transmission system of the electric moped is improved, the transmission precision is improved, the battery endurance is further improved, the riding comfort is improved, and the aesthetic design of appearance is improved.

For further understanding of the present invention, the following detailed description of the preferred embodiments will be provided in conjunction with the drawings and figures to illustrate the specific components of the present invention and the functions performed thereby.

Drawings

FIG. 1 is a schematic cross-sectional view of an embodiment of a harmonic drive system of an electrically assisted vehicle according to the present invention.

Fig. 2 is an exploded perspective view of the motor output shaft, compliant bearings, flexspline, cross roller bearing, and connector of the embodiment of fig. 1.

FIG. 3 is a schematic top view of the combination of the crossed roller bearing, flexspline, and wave generator of the embodiment of FIG. 1.

FIG. 4 is a schematic cross-sectional view of a harmonic drive system of an electric bicycle according to an embodiment of the present invention installed on a frame of the electric bicycle.

FIG. 5 is a schematic cross-sectional view of another embodiment of a harmonic drive system of an electric bicycle according to the present invention installed on a frame of the electric bicycle.

FIG. 6 is a schematic flow chart showing four situation modes of the harmonic transmission system of the electric bicycle according to the present invention.

FIG. 7 is a schematic cross-sectional view of an embodiment of a planetary gear transmission of a prior art electric bicycle.

Fig. 8 is an enlarged partial cross-sectional schematic view of the prior art embodiment of fig. 7.

Description of reference numerals: 1, an electric bicycle harmonic drive system; 10 a frame; 11, a five-way pipe; 12, a middle tube; 13, an inclined pipe; 14 a housing; 15 chain plate; 16 middle shaft; 17, a one-way ratchet wheel; 2 an electric motor; 20 a motor stator; 21 a motor rotor; 22 motor output shaft; 23 inner ring of motor output shaft; 24 a first end of a motor output shaft; 240 an extension of a first end of the motor output shaft; 25 a second end of the motor output shaft; 26 an elliptical cam; 27 an extension of the second end of the motor output shaft; 28 a fixed part of the first end of the motor output shaft; 29 motor output rotating shaft; 3, a wave generator; 30 a flexible bearing; 31 an inner race of the compliant bearing; a 32 harmonic reducer; 33 harmonic reducer rotating shaft; 4, a flexible gear; 40 a flexspline body; 41 inner ring of flexible gear body; 42 a first end of the flexspline body; 43 an outer gear; 44 a second end of the flexspline body; 45 a flexspline extension; 5 a cross roller bearing; 51 a crossed roller bearing inner ring; 52 a first end of the inner race of the cross roller bearing; 53 internal gear; 54 a second end of the inner race of the crossed roller bearing; 540 an inner race of a second end of the inner race of the crossed roller bearing; 55 an outer groove; 56 crossed roller bearing outer race; 560 inner race of crossed roller bearing outer race; 57 an inner groove; 58 cross roller accommodating space; 59 a cross roller; 6, connecting pieces; 61 a first end of a connector; 62 a second end of the connector; 63 an inner race of a second end of the connector; 64 an extension of the second end of the connector; 65 inner race of extension of the second end of the connector; 7 a first one-way clutch; 70 a torsion sensor; 71 a first end of a torsion sensor; 72 a second end of the torsion sensor; 73 inputting a rotating shaft; 8 a first bearing; 80 a second bearing; 81 a third bearing; 82 a fourth bearing; 83 a fifth bearing; 84 a fifth bearing inner ring; 85 a second one-way clutch; 86 a first shaft retaining ring; 87 second shaft retaining ring; 88 batteries; 89 copper sleeve; 9 a planetary gear transmission; 91 middle shaft; 92 an electric motor; 93 a hollow connecting shaft; 94 a hollow wheel; 95 a planetary gear; 96 center wheels; 97 a chain; 98 a braking device; 99 planet carrier.

Detailed Description

Please refer to fig. 1, which is a schematic cross-sectional view illustrating a harmonic transmission system of an electric bicycle according to an embodiment of the present invention. The invention discloses an electric bicycle harmonic drive system 1, which comprises a shell 14, a motor stator 20, a motor rotor 21, a motor output shaft 22, a flexible bearing 30, a flexible gear 4, a crossed roller bearing 5, a connecting piece 6, two first bearings 8, two second bearings 80, a third bearing 81, a fourth bearing 82, two fifth bearings 83, a retaining ring 86 for a first shaft, a retaining ring 87 for a second shaft, a first one-way clutch 7, a second one-way clutch 85 and a torque sensor 70. The electric bicycle harmonic drive system 1 is disposed in a bottom bracket 11 of a frame 10 of an electric bicycle (see fig. 4 and 5). The motor stator 20 is fixed to the housing 14. The motor stator 20 has an inner race. The motor rotor 21 is accommodated in the inner ring of the motor stator 20. The motor rotor 21 has an inner race. The two second bearings 80 and the second one-way clutch 85 are accommodated in the inner race of the motor rotor 21, wherein the second one-way clutch 85 is disposed between the two second bearings 80. In some embodiments, the two second bearings 80 comprise at least one selected from the group of: a ball bearing and a needle bearing, wherein the ball bearing can be a deep groove ball bearing. Fig. 2 is an exploded perspective view of the motor output shaft, the flexible bearing, the flexspline, the cross roller bearing and the connecting member of the embodiment of fig. 1. The motor output shaft 22 has a first end 24 and a second end 25. The first end 24 of the motor output shaft 22 includes a fixed portion 28 and an extended portion 240. The second end 25 of the motor output shaft 22 has an elliptical cam 26. The second end 25 of the motor output shaft 22 also includes an extension 27. The third bearing 81 has an inner race for receiving the extension 27 of the second end 25 of the motor output shaft 22. In some embodiments, the third bearing 81 includes at least one selected from the group consisting of: a ball bearing and a needle bearing, wherein the ball bearing can be a deep groove ball bearing. The fourth bearing 82 has an inner race. The two second bearings 80 each have an inner race. The second one-way clutch 85 has an inner race. The fifth bearing 83 has an inner race. The inner race of the fourth bearing 82, the inner races of the two second bearings 80 and the inner race of the second one-way clutch 85 are adapted to receive the first end 24 of the motor output shaft 22; the inner race of fifth bearing 83 receives an extension 240 of first end 24 of motor output shaft 22; wherein the fourth bearing 82 is disposed between one of the two second bearings 80 and the elliptical cam 26 of the second end 25 of the motor output shaft 22, the second one-way clutch 85 is disposed between one of the two second bearings 80 and the other one of the two second bearings 80, and the other one of the two second bearings 80 is disposed between the second one-way clutch 85 and the fifth bearing 83. In some embodiments, the fourth bearing 82 includes at least one selected from the group consisting of: a ball bearing and a needle bearing, wherein the ball bearing can be a deep groove ball bearing. The fifth bearing 83 further has a fifth bearing inner ring 84, a first shaft retaining ring 86 and the fixing portion 28 of the first end 24 of the motor output shaft 22 for fixing the fifth bearing inner ring 84 of the fifth bearing 83 on the motor output shaft 22 to prevent axial displacement. In some embodiments, the two fifth bearings 83 comprise at least one selected from the group of: a ball bearing and a needle bearing, wherein the ball bearing can be a deep groove ball bearing. The motor rotor 21, the motor stator 20, the two second bearings 80, the second one-way clutch 85 and the motor output shaft 22 form an electric motor 2, wherein the motor output shaft 22 has a motor output rotating shaft 29. The electric motor 2 comprises one selected from the group of: a brushless DC motor and a brushed DC motor. The compliant bearing 30 has an inner race 31 for receiving the elliptical shaped cam 26 of the second end 25 of the motor output shaft 22 to deform the compliant bearing 30 into an elliptical shape. Wherein the elliptical cam 26 of the second end 25 of the motor output shaft 22 and the flexible bearing 30 form a wave generator 3. The flexible gear 4 includes a flexible gear body 40 and a flexible gear outer extension 45. The flexspline body 40 has an inner race 41. A first end 42 of the flexspline body 40 has an outer gear 43. The wave generator 3 (the elliptical cam 26 and the compliant bearing 30 at the second end 25 of the motor output shaft 22) is accommodated in the inner race 41 of the flexspline body 40 at an external gear 43 corresponding to the first end 42 of the flexspline body 40, and deforms the first end 42 of the flexspline body 40 into an elliptical shape. The flexspline outer extension 45 is connected to a second end 44 of the flexspline body 40. The flexible wheel extension 45 extends outward from the second end 44 of the flexible wheel body 40, so that the flexible wheel 4 forms a hollow hat shape, wherein the flexible wheel extension 45 is a hat rim portion. The cross roller bearing 5 includes a cross roller bearing inner ring 51, a cross roller bearing outer ring 56, and a plurality of cross rollers 59. A first end 52 of the crossed roller bearing inner race 51 is fixed to the housing 14. The first end 52 of the crossed roller bearing inner race 51 has an inner gear 53 for meshing with the outer gear 43 at the first end 42 of the flexspline body 40. Please refer to fig. 3, which is a top view of the combination of the crossed roller bearing, the flexspline and the wave generator of the embodiment of fig. 1. Wherein the first end 52 of the cross roller bearing inner ring 51 of the cross roller bearing 5 (inner gear 53), the flexspline 4 and the wave generator 3 (elliptical cam 26 and compliant bearing 30 of the second end 25 of the motor output shaft 22) form a harmonic reducer 32. The harmonic reducer 32 has a harmonic reducer rotational shaft 33, wherein the harmonic reducer rotational shaft 33 of the harmonic reducer 32 coincides with the motor output rotational shaft 29 of the motor output shaft 22. A second end 54 of the crossed roller bearing inner ring 51 has an inner race 540 and an outer groove 55. The inner race 540 of the second end 54 of the crossed roller bearing inner race 51 is configured to receive the second end 44 of the flexspline body 40. The crossed roller bearing outer race 56 has an inner race 560 and an inner groove 57. The inner race 560 of the cross roller bearing outer race 56 receives the second end 54 of the cross roller bearing inner race 51. The inner groove 57 of the crossed roller bearing outer ring 56 is located corresponding to the outer groove 55 of the crossed roller bearing inner ring 51, so that a crossed roller accommodating space 58 is formed between the inner groove 57 of the crossed roller bearing outer ring 56 and the outer groove 55 of the crossed roller bearing inner ring 51. A plurality of cross rollers 59 are accommodated in the cross roller accommodating space 58. The connecting member 6 has a first end 61 and a second end 62. The flexspline outer extension 45 of the flexspline 4 is connected to the cross roller bearing outer race 56 and the first end 61 of the connector 6, respectively. The second end 62 of the connector 6 also includes an extension 64. The second end 62 of the connecting member 6 and the extension 64 of the second end 62 of the connecting member 6 are received within the inner race 41 of the flex spline body 40 proximate the second end 44 of the flex spline body 40. The extension 64 of the second end 62 of the connecting element 6 has an inner collar 65. The third bearing 81 is received within the inner race 65 of the extension 64 of the second end 62 of the connecting member 6. The second end 62 of the connecting element 6 has an inner collar 63. The first one-way clutch 7 is received in the inner race 63 of the second end 62 of the connecting member 6. The torsion sensor 70 has a first end 71 and a second end 72. The first one-way clutch 7 has an inner race. The first end 71 of the torque sensor 70 is received in the inner race of the first one-way clutch 7. The motor output shaft 22 has an inner race 23. The second end 72 of the torque sensor 70 is received in the inner race 23 of the motor output shaft 22 near the second end 25 of the motor output shaft 22 and the extension 27 of the second end 25 of the motor output shaft 22. Two first bearings 8 are accommodated in the inner ring 23 of the motor output shaft 22 near a first end 24 of the motor output shaft 22. The first end 71 of the torque sensor 70 is connected to a chain wheel 15 of the moped. The torque sensor 70 has an inner race. The two first bearings 8 each have an inner race. A middle shaft 16 of the electric bicycle is accommodated in the inner ring of each of the two first bearings 8 and the inner ring of the torque sensor 70, and the second end 72 of the torque sensor 70 is connected to the middle shaft 16 of the electric bicycle. At least one of the first bearings 8 has an inner ring, and the second shaft snap ring 87 is used to fix the inner ring of the first bearing 8 to the middle shaft 16 of the moped to prevent axial displacement. In some embodiments, the two first bearings 8 comprise at least one selected from the group of: a ball bearing and a needle bearing, wherein the ball bearing can be a deep groove ball bearing. The torque sensor 70 has an input rotation shaft 73, the input rotation shaft 73 of the torque sensor 70 is overlapped with the rotation shaft 33 of the harmonic reducer 32, and the input rotation shaft 73 of the torque sensor 70 is overlapped with the motor output rotation shaft 29 of the motor output shaft 22. A copper sleeve 89 may be added, and the copper sleeve 89 is accommodated in the inner ring of the torque sensor 70. The copper sleeve 89 has an inner ring. The central shaft 16 of the electric bicycle is simultaneously accommodated in the inner ring of the two first bearings 8, the inner ring of the torque sensor 70 and the inner ring of the copper sleeve 89, so that the rotation of the central shaft 16 of the electric bicycle is more stable and the axial displacement is avoided.

Please refer to fig. 4, which is a schematic cross-sectional view illustrating an embodiment of a harmonic transmission system of an electric bicycle according to the present invention disposed on a frame of the electric bicycle. In this embodiment, the electric bicycle harmonic drive system 1 further includes a battery 88, wherein the battery 88 is electrically connected to the electric motor 2 of the electric bicycle harmonic drive system 1. The battery 88 may be a rechargeable battery. The electric bicycle harmonic drive system 1 is arranged in a five-way pipe 11 of a frame 10 of the electric bicycle; the battery 88 is disposed within a down tube 13 of the frame 10.

Please refer to fig. 5, which is a schematic cross-sectional view illustrating another embodiment of a harmonic transmission system of an electric bicycle according to the present invention disposed on a frame of the electric bicycle. In this embodiment, the electric bicycle harmonic drive system 1 further includes a battery 88, wherein the battery 88 is electrically connected to the electric motor 2 of the electric bicycle harmonic drive system 1. The battery 88 may be a rechargeable battery. The electric bicycle harmonic drive system 1 is arranged in a five-way pipe 11 of a frame 10 of the electric bicycle; battery 88 is disposed within a center tube 12 of frame 10.

The electric bicycle harmonic drive system 1 adopts a speed reduction structure of the harmonic speed reducer 32, can greatly reduce the volume and the weight of the electric bicycle harmonic drive system 1, and can arrange the electric bicycle harmonic drive system 1 in the five-way pipe 11 of the frame 10 of the electric bicycle. The design can improve the flexibility of the design and the arrangement of other parts such as the central shaft 16, the torque sensor 70 and the first one-way clutch 7 of the electric bicycle. Compared with the prior art that the harmonic drive system of the electric moped is externally hung outside the frame, the harmonic drive system of the electric moped can be hidden in the frame 10 of the electric moped by adopting the structure, so that the aesthetic design of the appearance can be improved. In addition, the harmonic reducer 32 has the advantages of high reduction ratio, high meshing rate, small volume, light weight, low noise, high transmission precision and the like, can effectively improve the battery endurance, and the harmonic transmission system 1 of the electric moped with high transmission precision runs smoothly and can improve the comfort level during riding.

When a user rides or uses the electric bicycle having the harmonic drive system 1 of the electric bicycle of the present invention, there are generally the following four situation modes. Please refer to fig. 6, which is a schematic flow chart of four situation modes of a harmonic transmission system of an electric bicycle according to the present invention. The first line, the second line, the third line and the fourth line in fig. 6 represent a situation mode one, a situation mode two, a situation mode three and a situation mode four, respectively, wherein the arrow direction of the lines represents the driving direction. For example, a line between the bottom bracket 16 and the torque sensor 70 represents the bottom bracket 16 carrying the torque sensor 70. Situation mode one: is a normal riding condition. When the user steps on the pedal to rotate the pedal in the forward direction, the central shaft 16 of the electric bicycle starts to rotate in the forward direction, and the torque sensor 70 senses a rotation torque value, the electric motor 2 starts to rotate according to the rotation torque value (the output torque of the electric motor 2 is related to the rotation torque value), and the torque output by the first end 71 of the torque sensor 70 on the chain plate 15 of the electric bicycle is increased through the harmonic reducer 32, so as to reduce the burden of the user; that is, the user steps on the pedal to rotate forward, so as to drive the middle shaft 16, the torque sensor 70 and the chain plate 15; the motor rotor 21 of the electric motor 2 rotates to drive the second one-way clutch 85, the wave generator 3, the flexible gear 4, the connecting piece 6, the first one-way clutch 7 and the chain plate 15; the chain wheel 15 rotates to drive a one-way ratchet 17 on a rear wheel axle (not shown) via a chain (not shown), and then drive a rear wheel (not shown) to rotate. Situation mode two: when the user wants to make the pedal rotate reversely (make the middle shaft 16 rotate reversely), the second one-way clutch 85 acts to disengage the motor output shaft 22 of the electric motor 2 from the motor rotor 21 of the electric motor 2, and the torque value sensed by the torque sensor 70 is zero (because of no load), so the motor rotor 21 of the electric motor 2 stops rotating; that is, the user steps on the pedal to rotate reversely, so as to drive the middle shaft 16, the torque sensor 70, the chain plate 15 and the one-way ratchet 17, and at the moment, the one-way ratchet 17 acts, so that the rear wheel cannot rotate reversely; the torque sensor 70 also drives the connecting member 6 to drive the flexible gear 4 and the wave generator 3 to drive the second one-way clutch 85, and at this time, the second one-way clutch 85 acts to separate the motor output shaft 22 of the electric motor 2 from the motor rotor 21 of the electric motor 2. Situation mode three: the electric motor 2 does not rotate when the battery 88 is dead, or the electric motor 2 does not rotate when the user does not want to use the electric motor 2 for assistance by cutting off the switch. If the first one-way clutch 7 is not provided, when the user steps on the pedal, the forward rotation of the middle shaft 16 not only drives the rotation of the torque sensor 70 to rotate the chain plate 15 forward, but also the torque sensor 70 drives the first one-way clutch 7 and the harmonic reducer 32 to rotate together. However, since the harmonic reducer 32 has a large reduction ratio, the user feels hard when stepping on the foot pedal. Therefore, in the situation mode three, the first one-way clutch 7 of the electric bicycle harmonic transmission system 1 of the present invention can function to disengage the first one-way clutch 7 from the harmonic reducer 32, so as to greatly reduce the load caused by the linkage of the harmonic reducer 32 when the user steps on the pedal; that is, the user steps on the pedal to rotate in the forward direction, so as to drive the middle shaft 16, the torque sensor 70, the chain plate 15, the one-way ratchet 17 and the rear wheel; the torque sensor 70 also drives the first one-way clutch 7, and the first one-way clutch 7 is activated to disengage the first one-way clutch 7 from the connecting member 6 (harmonic reducer 32). Situation mode four: sometimes, a user needs to back up in a car pulling mode, the rear wheel rotates reversely, the one-way ratchet 17 is driven, the chain disc 15 is driven, the torsion force sensor 70 is driven, and the middle shaft 16 is driven to rotate reversely; at this time, the torque value sensed by the torque sensor 70 is zero (because of no load), so the motor rotor 21 of the electric motor 2 does not rotate; meanwhile, the torque sensor 70 drives the first one-way clutch 7 to drive the connecting member 6, the flexible gear 4, the wave generator 3 and the second one-way clutch 85, and the second one-way clutch 85 acts to separate the motor output shaft 22 of the electric motor 2 from the motor rotor 21 of the electric motor 2, so that the vehicle can be backed up without being locked.

In some preferred embodiments, the harmonic reducer 32 has a reduction ratio that is greater than or equal to 20 and less than or equal to 50.

In some preferred embodiments, the outer gear 43 has an outer gear modulus. The inner race 31 of the compliant bearing 30 has a compliant bearing inner race diameter. The elliptical cam 26 at the second end 25 of the motor output shaft 22 has a major axis and a minor axis, the major axis being greater than the minor axis. Wherein the long axis is more than or equal to the diameter of the flexible bearing inner ring plus 1.8 times of the modulus of the external gear, and is less than or equal to the diameter of the flexible bearing inner ring plus 2.4 times of the modulus of the external gear; the minor axis is larger than or equal to the modulus of the external gear obtained by subtracting 2.4 times from the diameter of the flexible bearing inner ring, and is smaller than or equal to the modulus of the external gear obtained by subtracting 1.8 times from the diameter of the flexible bearing inner ring.

The flexspline outer gear 34 has a flexspline outer tooth count. In some preferred embodiments, the number of meshing teeth of the external flexspline gear 34 meshing with the internal circular spline gear 40 is greater than or equal to 15% of the number of external flexspline gears, and less than or equal to 30% of the number of external flexspline gears.

In summary, the present invention can achieve the intended purpose of the invention and provide a harmonic transmission system for an electric bicycle, which has great industrial value.

Claims (20)

1. The utility model provides an electric bicycle harmonic drive system, sets up in a five-way pipe of a frame of an electric bicycle, its characterized in that, this electric bicycle harmonic drive system includes:

a housing;

a motor stator fixed on the shell, the motor stator having an inner ring;

a motor rotor accommodated in the inner ring of the motor stator, the motor rotor having an inner ring;

at least one second bearing, each of which has an inner ring;

a second one-way clutch, the second one-way clutch and the at least one second bearing being received within the inner race of the motor rotor, the second one-way clutch having an inner race;

a motor output shaft having an inner race, a first end of the motor output shaft being received in the inner race of the second one-way clutch and the inner race of each of the at least one second bearing, a second end of the motor output shaft having an elliptical cam, wherein the motor rotor, the motor stator and the motor output shaft form an electric motor;

at least one first bearing accommodated in the inner ring of the first end of the motor output shaft, each of the at least one first bearing having an inner ring;

a flexible bearing having an inner race for receiving the elliptical cam at the second end of the motor output shaft to deform the flexible bearing into an elliptical shape, wherein the elliptical cam at the second end of the motor output shaft and the flexible bearing form a wave generator;

a flexspline comprising:

the flexible gear comprises a flexible gear body and a flexible gear body, wherein the flexible gear body is provided with an inner ring, a first end of the flexible gear body is provided with an outer gear, and the wave generator is accommodated in the inner ring of the first end of the flexible gear body so as to enable the first end of the flexible gear body to be deformed into an elliptical shape; and

the flexible gear extension part is connected with a second end of the flexible gear body and extends outwards from the second end of the flexible gear body, so that the flexible gear forms a hat shape;

a crossed roller bearing comprising:

a crossed roller bearing inner ring, wherein a first end of the crossed roller bearing inner ring is fixed on the shell, the first end of the crossed roller bearing inner ring is provided with an inner gear for being meshed with the outer gear at the first end of the flexible gear body, a second end of the crossed roller bearing inner ring is provided with an inner ring and an outer groove, and the inner ring at the second end of the crossed roller bearing inner ring is used for accommodating the second end of the flexible gear body;

a crossed roller bearing outer ring having an inner ring and an inner groove, the inner ring of the crossed roller bearing outer ring for receiving the second end of the crossed roller bearing inner ring, the inner groove of the crossed roller bearing outer ring being located corresponding to the outer groove of the crossed roller bearing inner ring

A groove, so that a crossed roller accommodating space is formed between the inner groove of the crossed roller bearing outer ring and the outer groove of the crossed roller bearing inner ring; and

a plurality of cross rollers accommodated in the cross roller accommodating space;

a connecting piece, having a first end and a second end, wherein the flexible gear outer extension part of the flexible gear is respectively connected with the crossed roller bearing outer ring and the first end of the connecting piece, and the second end of the connecting piece is provided with an inner ring;

a first one-way clutch accommodated in the inner ring of the second end of the connecting piece, the first one-way clutch having an inner ring; and

the torque sensor is provided with an inner ring, a first end of the torque sensor is contained in the inner ring of the first one-way clutch, the first end of the torque sensor is connected with a chain disc of the electric moped, the inner ring of each first bearing and the inner ring of the torque sensor are used for containing a center shaft of the electric moped, and a second end of the torque sensor is connected with the center shaft of the electric moped.

2. An electric bicycle harmonic drive system as in claim 1 wherein: the at least one second bearing comprises at least one selected from the group consisting of: a ball bearing and a needle bearing.

3. An electric bicycle harmonic drive system as in claim 1 wherein: the second end of the torque sensor is accommodated in the inner ring of the second end of the motor output shaft.

4. An electric bicycle harmonic drive system as in claim 1 wherein: the second end of the motor output shaft further comprises an extension part, the second end of the connecting piece further comprises an extension part, the extension part of the second end of the connecting piece is provided with an inner ring for accommodating the third bearing, and the third bearing is provided with an inner ring for accommodating the extension part of the second end of the motor output shaft.

5. An electric bicycle harmonic drive system as in claim 4 wherein: the third bearing comprises at least one selected from the group consisting of: a ball bearing and a needle bearing.

6. An electric bicycle harmonic drive system as in claim 1 wherein: the motor also comprises a fourth bearing, wherein the fourth bearing is provided with an inner ring, the first end of the motor output shaft is contained in the inner ring of the fourth bearing and the inner ring of the motor rotor, and the fourth bearing is positioned between the motor rotor and the second end of the motor output shaft.

7. An electric bicycle harmonic drive system as in claim 6 wherein: the fourth bearing comprises at least one selected from the group consisting of: a ball bearing and a needle bearing.

8. An electric bicycle harmonic drive system as in claim 1 wherein: the first end of the motor output shaft also comprises an extension part, wherein the fifth bearing is provided with an inner ring, and the extension part of the first end of the motor output shaft is accommodated in the inner ring of the fifth bearing.

9. An electric bicycle harmonic drive system as in claim 8 wherein: the first end of the motor output shaft further comprises a fixing part, and the first shaft retaining ring and the fixing part at the first end of the motor output shaft are used for fixing the fifth bearing inner ring of the fifth bearing on the motor output shaft.

10. An electric bicycle harmonic drive system as in claim 8 wherein: the fifth bearing comprises at least one selected from the group consisting of: a ball bearing and a needle bearing.

11. An electric bicycle harmonic drive system as in claim 1 wherein: the at least one first bearing comprises at least one selected from the group consisting of: a ball bearing and a needle bearing.

12. An electric scooter harmonic drive system as claimed in claim 2, 5, 7, 10 or 11 wherein: the ball bearing is a deep groove ball bearing.

13. An electric bicycle harmonic drive system as in claim 1 wherein: the electric bicycle further comprises a second shaft snap ring, wherein the at least one first bearing is provided with an inner ring, and the second shaft snap ring is used for fixing the inner ring of the at least one first bearing on the middle shaft of the electric bicycle.

14. An electric bicycle harmonic drive system as in claim 1 wherein: the electric motor comprises one selected from the following group: a brushless DC motor and a brushed DC motor.

15. An electric bicycle harmonic drive system as in claim 1 wherein: the electric motor also comprises a battery, wherein the battery is electrically connected with the electric motor.

16. The electric-assisted vehicle harmonic drive system of claim 15, wherein: the battery is a rechargeable battery.

17. The electric-assisted vehicle harmonic drive system of claim 15, wherein: the battery is arranged in a middle tube or an inclined tube of the frame.

18. An electric bicycle harmonic drive system as in claim 1 wherein: the first end of the crossed roller bearing inner ring of the crossed roller bearing, the flexible gear and the wave generator form a harmonic reducer, and a harmonic reducer rotating shaft of the harmonic reducer is superposed with a motor output rotating shaft of the motor output shaft.

19. The electric-assisted vehicle harmonic drive system of claim 18, wherein: the rotating shaft of the harmonic reducer is superposed with an input rotating shaft of the torque sensor.

20. An electric bicycle harmonic drive system as in claim 1 wherein: the first end of the crossed roller bearing inner ring of the crossed roller bearing, the flexible gear and the wave generator form a harmonic reducer, and a harmonic reducer rotating shaft of the harmonic reducer is superposed with an input rotating shaft of the torsion sensor.

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