TWI822582B - Downsizing electric bicycle booster mechanism - Google Patents

Abstract

A reduced electric bicycle power-assisting mechanism, including an inverted harmonic reduction mechanism output by a rigid ring gear, a linear actuator, a left fixed shaft, a right fixed shaft and a hub shell, and is assembled by supporting and connecting accessories, in which the linear actuator is The actuator is installed in the hollow space inside the harmonic reduction mechanism, and is locked to the left fixed axis and the right fixed axis. The linear actuator has a plurality of radial actuating rods with two radial ends sequentially along the circumferential direction. The actuator rod drives the inverted harmonic reduction mechanism. Compared with the electric bicycle power-assist device technology on the market or other announced patents, which uses an inner-rotor or outer-rotor hub motor to drive a gear reduction mechanism, it clearly has the effect of reducing the axial size.

Description

Shrinking the power-assisted mechanism of electric bicycles

The present invention relates to a reduced power-assisting mechanism for an electric bicycle, and in particular, to a technology for an electric bicycle power-assisting mechanism that can achieve smaller size, lighter weight, and improve the power-assisting effect.

Due to environmental protection and the impact of previous epidemics, major cities around the world encourage citizens to use bicycles as transportation. When commuting or leisure destinations are far away or there are uphill sections on the road, electric bicycles with motor assist devices More in line with needs.

Currently, the commonly used power-assisting devices for electric bicycles on the market use hub motors (hub motors), which can be divided into outer-rotor hub motors and inner-rotor hub motors. They can also be divided into gearless hub motors and inner-rotor hub motors according to whether there is a gear reduction mechanism in the motor. There are gear hub motors. The gear reduction mechanism in commonly used toothed external rotor hub motors on the market actually uses a simple centering gear system, including a sun gear (input wheel), three intermediate idler gears and ring teeth (output wheel), so its The reduction ratio is not high. For example, the reduction ratio of a sun gear with 21 teeth and a ring gear with 93 teeth is only -4.4. New Patent No. M484555 "Bicycle power-assist motor with one-way function" uses a compound gear train inner rotor hub motor. The large-diameter gear part and the small-diameter gear part are pinned to the same shaft and are connected to the sun gear (input wheel) and gear respectively. circle (lose The reduction ratio of this compound gear system is through the matching teeth (for example, the 20 teeth of the sun gear drive the 60 teeth of the large-diameter gear, and the 20 teeth of the small-diameter gear that rotates together with the large-diameter gear drive the 93 teeth of the ring gear) A higher reduction ratio (approximately -14) can be obtained than a simple center gear train, but it also requires a large gear fit. It can be seen that the gear reduction mechanism of the hub motor on the market has poor deceleration and torque improvement effects, making it difficult to climb long and steep slopes.

The planetary gear reduction mechanism without sun gear and small tooth difference has a higher reduction ratio than the center gear train with sun gear (including simple and compound gear trains), so it can greatly improve the output torque effect of the hub motor. Moreover, the number of teeth can be smaller, which means smaller volume and weight. The first-order planetary gear reduction mechanism with small tooth difference without sun gear includes cycloidal pinwheel reducer, harmonic reducer, and first-order involute small tooth difference planetary gear reduction mechanism. Therefore, the invention patent No. I694951 "Cycloidal gear transmission in electric bicycle power assist system" adopts an inner rotor motor and a cycloidal pinwheel reducer; the invention patent No. I694952 "Harmonic gear transmission mechanism for electric power assistance of electric bicycles" adopts Inner-rotor motor and harmonic reducer; Invention Patent No. I773222 "Electric bicycle power-assisting device with inner-rotor hub motor with first-order involute small-tooth-difference planetary gear reduction transmission mechanism" uses an inner-rotor motor and a first-order involute Open-line small-tooth-difference planetary gear reduction mechanism; Invention Patent No. I786567 "Electric bicycle power-assisting device with first-order involute small-tooth-difference planetary gear reduction transmission mechanism and external rotor hub motor" uses an external rotor motor and a first-order Involute small tooth difference planetary gear reduction mechanism.

Although the manufacturing cost of the harmonic reducer is relatively high, as far as the first-order small tooth difference planetary gear reduction mechanism is concerned, the advantage of the harmonic reducer is that it drives the input shaft of the output integrated planetary gear (including the flexible gear and the rigid ring cup) Use camshaft for centering The shaft, that is, the output shaft and the input shaft are both on the same axis. Unlike the first-order cycloidal pinwheel reducer and the first-order involute small-tooth-difference planetary gear reduction mechanism, the planetary gear is driven by the eccentric shaft (pin), so harmonic deceleration The machine does not need an additional hole-pin jointed constant-speed centering mechanism like the first-order cycloidal pinwheel reducer and the first-order involute small-tooth-difference planetary gear reduction mechanism to convert the rotation of the eccentric shaft into the rotation of the central shaft. Output motion, which is why harmonic reducers are currently widely used in the industry.

The casing 10 in the invention patent No. I694952 "Harmonic gear transmission mechanism for electric power assist of electric bicycles" is not used to drive the rim of the electric bicycle to rotate, but to lock the motor end side cover and the rigid wheel 30, and For fixing internal parts, the hollow shaft 70 is driven by the inner rotor 21 of the motor, and drives the output disk 50 through the cam ring 80 and the flexible bearing 42 set on the hollow shaft. However, the only components for rotating output are the output disk 50 on the right and The invention content does not explain how the combination of the output disk 50 and the end cover 51 on one side drives the center wheel to rotate through the spokes connecting the wheel frame. In addition, the motor drives the hollow shaft 70 as a Rotate the central axis, but the content of the invention does not include the center axis of the hub connected to the front fork and rear fork of the frame, or specifically explains how its housing 10 (fixing member) is installed and fixedly connected to the front fork and rear fork of the frame. where is the fork or frame. In addition, this invention patent and the other three invention patents mentioned above all use an inner rotor or outer rotor hub motor to drive the gear reducer. The electric bicycle power-assist device still has the disadvantage of being too large (please refer to the cross-sectional view of the motor or the gear reducer in each invention patent). The hub motor configuration will be known).

The present invention is mainly aimed at the above-mentioned shortcomings of the invention patent No. I694952 "Harmonic gear transmission mechanism for electric power assist of electric bicycles" and the existing problems of the electric bicycle power assist device using an inner rotor hub motor to drive the harmonic gear reduction mechanism. A brand new invention caused by the disadvantage of excessive size.

The main purpose of the present invention is to provide a reduced power-assisted mechanism for electric bicycles. One of the main technical features is the use of an inverted harmonic gear reduction mechanism, which uses a rigid ring gear as the output wheel, an integrated planetary wheel with a flexible gear and a rigid ring cup (this The invention is called an integrated external gear with a flexible gear on the left and a rigid ring cup on the right) as a fixed member; another main technical feature is that a linear actuator is used to replace the rotor hub motor to drive the electric bicycle power-assist mechanism of the inverted harmonic gear reduction mechanism. , since the axial configuration of the power assist device does not require a rotor-type hub motor, the axial size can be reduced, miniaturization and weight reduction can be achieved, while still maintaining the boosting effect.

The traditional harmonic gear reduction mechanism uses a rigid ring gear as the fixed component (frame), and an integrated planetary wheel with a flexible gear and a rigid ring cup as the output wheel. It is well known that the reduction ratio is - (number of teeth of the flexible gear) divided by (rigid The number of teeth of the ring gear - the number of teeth of the flexible gear), for example, the number of teeth of the rigid ring gear is 22 and the number of teeth of the flexible gear is 20, and the reduction ratio is -10; the number of teeth of the rigid ring gear is 52 and the number of teeth of the flexible gear is 50, and the reduction ratio is -25; the number of teeth of the rigid ring gear is -25 102. The number of teeth of the flexible gear is 100, and the reduction ratio is -50. The present invention uses an inverted harmonic gear reduction mechanism with the rigid ring gear as the output wheel and the integrated external gear as the fixed component. The reduction ratio can be obtained from the planetary gear motion analysis list method or the planetary gear motion analysis formula method in the mechanics textbook: (Number of teeth of rigid ring gear) divided by (Number of teeth of rigid ring gear - Number of teeth of flexible gear). Therefore, the number of teeth of the rigid ring gear is 22 and the number of teeth of the flexible gear is 20, and the reduction ratio is 11 (representing a 10% increase in torque compared to the traditional harmonic gear reduction mechanism mentioned above); the number of teeth of the rigid ring gear is 52 and the number of teeth of the flexible gear is 50, and the reduction ratio is 26 (Represents a 4% increase in torque compared to the above); the number of teeth of the rigid ring gear is 102, the number of teeth of the flexible gear is 100, and the reduction ratio is 51 (generation The table torque increases by 2% compared to the above). In addition to the increase in torque compared to the traditional harmonic gear reduction mechanism using an inverted harmonic gear reduction mechanism of the same size, an integrated external gear is used as a fixed component. Compared with the traditional use of an integrated planetary gear with a flexible gear when the output rotating wheel is in The fatigue life will be better.

The technical means to achieve the object of the present invention include an inverted harmonic gear reduction mechanism, a linear actuator, a left fixed shaft, a right fixed shaft and a hub shell, and are assembled by supporting and connecting accessories to form a reduced electric motor with the effect of the present invention. Bicycle power assist device. The hub shell includes a shell main body, a right side cover of the shell and a left side cover of the shell. The inverted harmonic gear reduction mechanism includes a rigid ring gear that is interference-fitted in the main body of the housing, an integrated external gear train with a left flexible gear and a right-side rigid ring cup, and a flexible bearing (or flexible bushing) that is interference-fitted to the integrated external gear. The inner diameter of the left flexible gear. The linear actuator has a plurality of radial actuator rods, which are arranged in the internal hollow space of the inverted harmonic gear reduction mechanism, and are locked to the left fixed axis and the right fixed axis, replacing the wheel hub motor and the wheel hub rotating shaft. Additional axial and radial space is required to install a traditional hub motor and hub shaft. Please refer to Figure 1 for the above action, which is a schematic diagram of a linear actuator driving a rigid ring gear with two radial end actuating rods sequentially along the circumferential direction. The plurality of radial actuating rods of the linear actuator 21 include two actuated rods. When the two adjacent radial ends of the two unactuated execution rods 23 start to contact the flexible bearing 15 inside the left flexible gear 13, the first two actuated execution rods 22 will Return to the non-driven position, and repeat this process by driving the meshing of the left flexible gear 13 and the rigid ring gear 11 and the difference in the number of teeth between the two to drive the rigid ring gear 11 to rotate and generate a deceleration motion.

11: Rigid ring gear

12:Integrated external gear

13:Left flexible gear

14: Right rigid ring cup

15:Flexible bearings

21: Linear actuator

22: The execution rod has been actuated

23: The execution rod is not actuated

31: Shell body

32: Cover on the right side of the shell

33: Cover on the left side of the shell

34:Screw

35: Right ball bearing

36: Left side ball bearing

37:Right seal

38:Left seal

41: Right fixed axis

411: Right fixed axis ladder

42: Left fixed axis

421: Left fixed axis ladder

43: Flat key

44:C type buckle

45:Screw

Figure 1 is a schematic diagram of a linear actuator driving a rigid ring gear with two actuating rods at the radial end sequentially along the circumferential direction.

Figure 2 is a cross-sectional view of a reduced power-assisted mechanism of an electric bicycle according to an embodiment of the present invention.

In order to help the review committee further understand the technical features and means of the present invention, specific embodiments are described in detail with illustrations as follows: Please refer to Figures 1 to 2 at the same time. Figure 2 is a reduced electric bicycle power assist according to an embodiment of the present invention. Sectional view of the mechanism. In the embodiment of the present invention, the hub shell of the reduced power-assisted electric bicycle includes a shell main body 31, a right shell cover 32 and a left shell cover 33. The right shell cover 32 and the left shell cover 33 are locked to the shell main body 31 by screws 34. Actually, When used, the hub shell can be connected to the wheel frame (not shown) through spokes (not shown), and the hub shell drives the wheel rim to rotate. The left fixed axis 42 and the right fixed axis 41 have a left fixed axis step 421 at the right end, and a right fixed axis step 411 at the left end of the right fixed axis 41. The left fixed axis 42 and the right fixed axis 41 are connected by the left fixed axis 42 and the right fixed axis 41. The ball bearing 36, the left seal 38 and the right ball bearing 35 and the right seal 37 are arranged on the central axis of the hub shell. The parts of the left fixed shaft 42 and the right fixed shaft 41 exposed outside the wheel hub shell can be connected by nuts (not shown). out) is locked on the front or rear fork of the frame (not shown). The inverted harmonic gear reduction mechanism includes a rigid ring gear 11, an integrated external gear 12, a left flexible gear 13 and a right rigid ring cup 14. The rigid ring gear 11 is interference assembled in the main body 31 of the shell, and the right rigid ring cup 14 is assembled using The flat key 43 and a C-shaped buckle 44 are fixed on the right fixed shaft 41, and the flexible bearing 15 is interference-fitted on the inner diameter of the left flexible gear 13. The linear actuator 21 has a plurality of radial execution rods, and the plurality of radial execution rods include an actuated execution rod 22 and other unactuated execution rods 23.

The linear actuator 21 is placed inside the hollow of the inverted harmonic gear reduction mechanism. The left and right sides of the space are locked to the left fixed axis step 421 and the right fixed axis step 411 by screws 45. The linear actuator 21 with a plurality of radial actuator rods moves radially clockwise or counterclockwise along the circumferential direction. The two actuated execution rods 22 at the end drive the meshing of the left flexible gear 13 and the rigid ring gear 11. When the next two adjacent radial end actuators contact the internal flexible bearing 15 of the left flexible gear 13, the previous one has Actuating the two actuating rods 22 will return to the undriven position, and so on again and again. Through the actuating rods (22 and 23) of the linear actuator 21 and the difference in the number of teeth between the left flexible gear 13 and the rigid ring gear 11, the rigid ring gear 11 is relatively stable. The deformed meshing but fixed left flexible gear 13 performs coaxial rotation. At the same time, the rigid ring gear 11 interference-fitted in the shell body 31 drives the hub shell to perform output rotation on the left ball bearing 36 and the right ball bearing 35.

In summary, the reduced electric bicycle power-assisting mechanism of the present invention is obviously capable of achieving a high reduction ratio and improving the power-assisting effect in a smaller size. The structural features specifically defined in the claims of the present invention are not found in similar articles, and it is industrially applicable and novel. It is innovative and progressive and has met the requirements for an invention patent. It is very convenient for me to file an application in accordance with the law and pray for review and grant of a patent.

11: Rigid ring gear

12:Integrated external gear

13:Left flexible gear

14: Right rigid ring cup

15:Flexible bearings

21: Linear actuator

22: The execution rod has been actuated

31: Shell body

32: Cover on the right side of the shell

33: Cover on the left side of the shell

34:Screw

35: Right ball bearing

36: Left side ball bearing

37:Right seal

38:Left seal

41: Right fixed axis

411: Right fixed axis ladder

42: Left fixed axis

421: Left fixed axis ladder

43: Flat key

44:C type buckle

45:Screw

Claims (1)

A reduced power-assisted mechanism for electric bicycles, including: The hub shell includes a shell main body, a right side cover and a left side cover. The right side cover and the left side cover are locked to the main body with screws. The hub shell can be connected to and drive the wheel rim to rotate; The left fixed shaft and the right fixed shaft have a left fixed shaft step on the right end, and a right fixed shaft step on the left end of the right fixed shaft. The left fixed shaft and the right fixed shaft are connected by ball bearings and seals on the left and right sides. It is arranged on the central axis of the wheel hub shell. The parts of the left fixed shaft and the right fixed shaft exposed outside the wheel hub shell can be connected to the front fork or rear fork of the frame; The inverted harmonic gear reduction mechanism includes a rigid ring gear, an integrated external gear train with a left flexible gear and a right rigid ring cup, in which a flexible bearing is interference-fitted to the inner diameter of the left flexible gear; The linear actuator has a plurality of radial actuator rods, which can drive the inverted harmonic gear reduction mechanism at high speed, and then the inverted harmonic gear reduction mechanism transmits it to the hub shell with a high reduction ratio; Its characteristics are: The rigid ring gear is interference assembled in the main body of the housing. The right rigid ring cup of the integrated planet wheel is fixed to the right fixed shaft through a flat key and a C-shaped retaining ring. The linear actuator is placed in the hollow interior of the inverted harmonic gear reduction mechanism. space, the left and right sides of the linear actuator are locked to the left fixed axis step and the right fixed axis step with screws. The linear actuator with multiple radial actuator rods moves radially clockwise or counterclockwise along the circumferential direction. The two actuated execution rods at the radial end drive the meshing of the left flexible gear and the rigid ring gear of the integrated external gear. When the next two adjacent radial end actuating rods actuate and contact the flexible bearing inside the left flexible gear, the previous one has actuated. The two actuating rods return to the undriven position, and the actuating rod of the linear actuator drives the left flexible tooth over and over again. The meshing of the wheel and the rigid ring gear, and through the difference in the number of teeth between the left flexible gear and the rigid ring gear, makes the rigid ring gear perform coaxial rotation relative to the deformable meshing but fixed left flexible gear, and at the same time drives the hub shell in the The two bearings of the left fixed shaft and the right fixed shaft perform output rotation.

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