WO2020220398A1 - Electric bicycle power centrally-arranged transmission assembly - Google Patents

Abstract

An electric bicycle power centrally-arranged transmission assembly, comprising a motor (2) that a rotor shaft is arranged horizontally, a crankset (4) transmitting power to bicycle wheels, a central shaft (1) providing pedal power to the crankset (4), a sun gear (31) coaxially fitted over the central shaft in a floating mode, a planet carrier (33) in linkage with the central shaft, and a planet gear (32) arranged in the planet carrier (33) in a penetrating mode and engaged with the sun gear (31); wherein a rotor shaft (211) passes through a through hole of the centering of the rotor shaft and is coaxially fitted over the central shaft (1) in a floating mode, and the rotor shaft (211) is in linkage with the sun gear (31); and the crankset (4) is coaxially fitted over the central shaft (1) in a floating mode, and the crankset (4) is engaged with the planet gear (32) in a transmission mode by means of an inner gear (41); and the rotor shaft (211) drives the planet gear (32) to rotate and output, and the central shaft (1) changes rotation output of the planet gear (32) by rotating the planet carrier (33). The transmission assembly can greatly optimize a structural size and improve the transmission conversion rate. Meanwhile, by means of matching of different speed ratios, multi-form modes are achieved, and good feeling of user experience is improved.

Description

Electric bicycle power transmission assembly Technical field

The invention relates to the field of electric bicycle power transmission structure, in particular to a power transmission assembly of an electric bicycle.

Background technique

The mid-mounted motor is a type of power mechanism that is widely used on electric bicycles. Its composition usually includes the motor body as the power source and the planetary reduction mechanism as the drive train, clutch, transmission gear set, and bottom shaft and chainring. Most of the output shaft of the central motor body is connected to the clutch through a planetary reduction mechanism, and then the clutch is connected to the shaft gear on the central shaft through an inner gear ring. But in fact, due to the size limitation of the central shaft itself, coupled with the occupation of the motor body and the necessary transmission parts, the size of the central transmission structure has been difficult to optimize. The situation is even more embarrassing, because the clutch structure cannot be disengaged in the transmission, the setting of the clutch will make the size of the power transmission structure increase unabated.

For example, the Chinese invention patent "Electric Vehicle Coaxial Mid-mounted Motor Drive Device", the application number is 200610005571.X. It discloses a motor and a pedal shaft with a coaxial transmission mode, and the pedal shaft must realize the transmission of kinetic energy with the flywheel through a clutch structure. Therefore, the overall size cannot be reduced, and the problem of clutch failure is also increased. The clutch structure is self-locking through friction, which will bring more unstable technical problems, but it is difficult to implement the solution. Applied.

In order to solve the above situation, some mid-mounted motors usually have a parallel deployment structure, in which the motor body and the central shaft are arranged in parallel. Compared with the original coaxial structure, the size settings of the motor body, planetary reduction mechanism, clutch and gear drive train in this type of central motor can no longer be restricted. However, in actual use, this type of mid-mounted motor still exposes the following shortcomings: First, the parallel spacing between the transmission shafts makes the transmission energy consumption higher, the kinetic energy conversion rate is reduced, and the motor can only be smaller; Therefore, most of these motors are 300 to 500 watts. Second, there are many parts, and the assembly is cumbersome. The overall structure size is greatly increased in the radial direction. Third, the burden and stress of the rotating shaft are large, resulting in a decrease in the reliability and stability of the mechanism. Therefore, this improved method does not perfectly solve the previous problem, but brings more defects. Fourth, since the size of the motor is easily limited, especially the thickness and diameter of the motor cannot be too large, the power of the motor will be restricted.

For example, the Chinese invention patent "E-bike compact mid-mounted motor", the application number is 201610264143.2, which uses the parallel arrangement of the motor rotor and the central shaft for structural arrangement. Although it can reduce the torque burden, it does not optimize the structure, and the axial volume and radial dimensions of the entire mechanism have not been reduced, making the structure of the entire mid-mounted motor more complicated and the assembly more complicated.

Therefore, it is urgent to design a power transmission structure for electric vehicles, which can not only solve the problem of size optimization, but also need to solve other technical problems caused by the current mid-mounted motors and transmissions, which can save energy and protect the environment. , It is also necessary to improve user experience and increase user trust.

Summary of the invention

The technical scheme of the present invention is a power transmission assembly of an electric bicycle, which includes a motor, a chain ring, a middle shaft, and a planetary gear train.

The motor includes a rotor and a stator, the center of the rotating shaft is the rotor shaft, and the rotor shaft is arranged horizontally. The stator is sleeved on the outside of the rotor, and the rotor rotates with the rotor shaft after power on.

The bottom axis is the pedal axis, and the bottom axis is used to provide pedal power.

The chain ring is used to transmit power to the wheels, and the power of the chain ring can be obtained from the motor or the bottom bracket. The power acquisition component of the chainring is an internal gear, and the tooth surface profile of the internal gear and the external tooth surface profile of the chainring are also in a coaxial relationship, so the internal gear is used to cooperate with the planetary gear system.

The planetary gear system includes a sun gear, a planet carrier, and a planet gear. The sun gear is located in the center of the planet gear, and the planet gear is installed on the planet carrier through the planet shaft.

The transmission relationship based on the above components is:

The rotor shaft is a hollow shaft, which is sleeved on the central shaft; the chain ring is coaxially sleeved on the central shaft; the planetary gear system is coaxially sleeved on the central shaft through the shaft hole of the sun gear center. In addition, the above-mentioned coaxial sleeve relationship are all clearance fits, that is, relative rotation can occur.

The specific transmission coordination is: the rotor shaft and the sun gear are synchronously linked, the planet carrier and the central shaft are synchronously linked, and the planetary gear is driven by the inner gear core.

Preferably, since the motor can achieve the effect of controlling the rotor speed by controlling the strength of the magnetic field, the rotation state of the rotor shaft can also be controlled; the rotation state of the rotor shaft includes: rotation direction, rotation speed, and whether to rotate. Due to the different rotation states of the rotor shaft, the chainring can have multiple output modes at different speeds of the central shaft.

For example, when the rotor shaft is in a non-rotating state (the magnetic force of the motor is maximized) and the center shaft rotates, the rotation of the center shaft is completely converted to the rotation of the chainring.

Preferably, a sensor for sensing shaft rotation parameters is provided on the central shaft, or on the rotor shaft, or on the central shaft and the rotor shaft. The sensor is used to obtain rotation parameters including: rotation speed, rotation direction, or rotation angle.

Preferably, the first sensor and the second sensor are resolvers, and the resolver can further calculate the basic signal required in the system by changing the magnitude of the output voltage with the angular displacement of the rotor.

Preferably, the rotation speed ratio of the crankset to the rotor is 1: (10-18), and a reasonable rotation speed ratio can maximize the transmission output effect and avoid unnecessary energy consumption.

Preferably, the revolving outer surface of the sun gear includes: a transmission tooth surface area and a transmission connection area.

Preferably, the transmission connection area includes spline grooves opened along the axial direction, and the inner surface of the through hole of the rotor shaft is also provided with splines.

Preferably, the central shaft is provided with a shoulder for fixing the planet carrier.

Preferably, a plane bearing is provided between the shaft shoulder and the end surface of the sun gear to reduce friction.

Preferably, a plane bearing is also provided between the crankset and the planet carrier to reduce the friction between the planes.

Preferably, the crankset and the rotor shaft are rotatably supported with the central shaft through corresponding bearing parts.

An electric bicycle includes a vehicle body and wheels. The vehicle body is provided with a power transmission assembly of the electric bicycle. The power transmission assembly of the electric bicycle includes: motor, chainring, bottom bracket, planetary gear train.

The rotor shaft of the motor is a hollow shaft, which is sleeved on the central shaft; the chainring is coaxially sleeved on the central shaft; the planetary gear train is coaxially sleeved on the central shaft through the shaft hole of the sun gear center. In addition, the above-mentioned coaxial sleeve relationship are all clearance fits, that is, relative rotation can occur.

The specific transmission coordination is: the rotor shaft and the sun gear are synchronously linked, the planet carrier and the central shaft are synchronously linked, and the planetary gear is driven by the inner gear core. On the basis of this transmission coordination, the output mode of the chainring is different so that the electric bicycle can achieve:

1. The electric mode that is powered by the motor only, 2. The riding mode that is powered by the pedal only, the hybrid mode where the pedal and the motor work at the same time, etc.

Based on the above-mentioned electric bicycle structure, sensors are arranged on the central shaft and the rotor shaft to sense rotation parameters, and the rotation parameters can be used for system control of the electric bicycle. A more specific exercise mode can be achieved according to the coordination of different speeds or different steering.

Based on the aforementioned bicycle with rotational parameter sensing function, the motor can be a three-phase permanent magnet synchronous motor, and the sensor can be a resolver. The effect is that the rotation of the three-phase permanent magnet synchronous motor has a magnetic angle, so the resolver can obtain the rotation angle of the rotor, and according to the "resolver condition", it can be solved into more accurate system feedback and system output.

Based on the above-mentioned electric bicycle, the transmission structure and matching conditions can be more perfect, for example: the connection between the rotor shaft and the sun gear can be matched by splines and spline grooves; the shaft shoulder on the center can not only position the planetary gear system, but also The planet carrier can be fixed; the sun gear and planet carrier as the main rotating parts can reduce the plane friction between the fits through the plane bearing.

The advantages of the present invention are:

First of all, its transmission principle determines its layout. The central layout can greatly optimize the structure size, reduce the weight of the car body, and save energy.

Secondly, the coaxial arrangement can directly transmit kinetic energy to the wheels, the additional loss in the power transmission process is greatly reduced, and the transmission response is more direct.

Third, in the coordination of the transmission, the power "disengagement", "mixing" and "combination" are mainly realized by the specific connection relationship and the matching method of the planetary gear train. No additional clutch structure is needed, so the structure can be further optimized, the size can be reduced, and the number of accessories can be reduced.

Fourth, the coaxial design makes the size of the motor unrestricted, and the power density of the motor is higher. Therefore, the power of the motor can reach 3000-5000 watts.

Description of the drawings

The present invention will be further described below in conjunction with the drawings and embodiments:

Figure 1 is the structure transfer diagram of the power transmission assembly of the electric bicycle;

Figure 2 is an exploded view of the structure of the power transmission assembly of the electric bicycle;

Figure 3 is a front view of the coaxial structure on the central axis;

Figure 4 is a cross-sectional view of the A-A section in Figure 3;

Figure 5 is a schematic diagram of the structure of the motor rotor;

Figure 6 is a schematic diagram of the coordination between the sun gear and the rotor shaft;

Among them: 1. Bottom shaft; 2. Motor; 3. Planetary gear system; 4. Chainring; 5. Resolver on the bottom shaft; 6. Resolver on the rotor shaft; 11. Crank; 12. Pedal 13. Bearing parts; 14. Shaft shoulder; 21. Rotor; 22. Stator; 211. Rotor shaft; 212. Magnet; 213. Through hole; 31. Sun gear; 32. Planetary gear; 33. Planet carrier; 311. Spline groove; 312, spline; 41, internal gear; 42, plane shaft.

Detailed ways

Example 1

A power transmission assembly for an electric bicycle includes a motor 2, a central shaft 1, a chain ring 4, and a planetary gear train 3. The bottom bracket 1 is the pedal shaft. The crank 11 is mounted on both ends of the bottom bracket 1, and the pedal 12 is mounted on the end of the crank 11. The motor 2, the chain ring 4, and the planetary gear train 3 all maintain a coaxial matching relationship with the central shaft. Therefore, in the arrangement structure of the electric bicycle, the motor 2 is in the middle position.

Specifically, the motor 2 includes a rotor 21 and a stator 22. There are many types of motors to choose from, such as brushless DC motors, reluctance motors, three-phase permanent magnet synchronous motors, and so on.

In this embodiment, as shown in FIG. 1, the rotor 21 includes a rotor shaft 211 and a magnet 212 sleeved on the rotor shaft, and the stator 22 includes a winding coil surrounding the rotor. The rotor shaft 211 has a hollow shaft structure, and the shaft center of the rotor shaft 211 has a through hole 213 penetrating the shaft center. The rotor shaft 211 is sleeved on the central shaft 1 through the through hole 213, and a clearance fit and non-interference relationship are maintained between the two. At the same time, the bottom bracket 1 also maintains the rotation support between it and the rotor shaft 211 through the bearing member A.

The matching structure of the crankset 4 and the central shaft 1 is similar to the above-mentioned method. The shaft center of the crankset 4 is also provided with a shaft hole penetrating the shaft center. The crankset 4 is sleeved on the central shaft 1 through the shaft hole. The clearance fit does not interfere with each other, and the crankset 4 and the central shaft 1 are also supported by the bearing member B to rotate.

Based on the above-mentioned mechanism, a basic "center-mounted coaxial" arrangement can be formed. The rotor shaft 211 and the crankset 4 are respectively maintained coaxially relative to the center shaft 1 through the bearing member 13. The reason why this method is better than the "off-axis" arrangement is that the "off-axis" arrangement will cause the motor power to be affected by the diameter and height of the motor. If the diameter of the motor increases, the differential torque of the chainring will be limited. If the number of motor laminations is increased, the pedal link will be blocked by the mechanism, and at the same time, a suitable clutch structure needs to be configured, and the structure will become larger.

The transmission arrangement between the rotor shaft 211 and the crankset 4 is realized by the planetary gear train 3. The planetary gear train 3 includes a sun gear 31, three planetary gears 32 and a planet carrier 33. The sun gear 31 is located in the center of the planet carrier 33, and three planet gears 32 surround the sun gear 31 and mesh with it for transmission. At the same time, three planetary gears 32 are installed on the planet carrier 33 through planet shafts.

The sun gear 31 is sleeved on the central shaft 1 between the chain ring 4 and the rotor shaft 211 through its shaft hole, and the sun gear 31 and the central shaft 1 are in clearance fit. Therefore, the planetary gear train 3 and the central shaft 1 also maintain a coaxial positional relationship. While the sun gear 31 maintains a meshing transmission relationship with the planetary gear 32, the sun gear 31 also maintains a synchronous linkage relationship with the rotor shaft 211. The synchronized linkage relationship can be a variety of docking relationships, such as welding, screw fastening, locking, etc. In this embodiment, the matching relationship between the spline 312 and the spline groove 311 is used to achieve it. Specifically, the outer surface of the sun gear 31 is divided into two independent areas: one is the transmission tooth surface area, and the other is the transmission connection area. The transmission tooth surface area meshes with the planetary gear 32, and the transmission connection area is the spline grooves 311 evenly arranged along the axial direction. At the same time, a corresponding spline 312 is provided on the inner turning surface of the mating port of the rotor shaft 211. Through this coordination method, the rotational force of the rotor can be directly transmitted to the planetary gear train.

The planetary gear train 3 is coaxially fitted in an internal gear 41 which is a part of the chain ring 4. As shown in Figures 1 and 4, an internal gear 41 is provided on the end face of the chain ring 4 facing the planetary gear train 3. The internal gear 41 is coaxial with the chain ring 4, and the planetary gear 32 meshes with the internal gear 41 for transmission. The rotation of the gear 32 will drive the chain ring 4 to rotate, and the rotational force at this time comes from the rotor of the motor.

The crankset 4 can not only obtain power from the motor, but also obtain rotational force from the central shaft. The transmission relationship between the bottom bracket 1 and the crankset 4 is also completed by the planetary gear train 3. The planet carrier 33 in the planetary gear train 3 is sleeved on the bottom bracket 1 and maintains a coaxial relationship with the bottom bracket 1, so The bottom bracket 1 and the planet carrier 33 are linked. The linkage relationship can be multiple, such as screw fastening, riveting, locking, etc. In this embodiment, welding is used to complete the fixed connection. Therefore, when the center shaft 1 obtains the rotational force provided by the pedals, the center shaft 1 synchronously drives the planet carrier 33 to rotate, and the planet carrier 33 provides the rotation of the crankset 4 through the revolution of the planetary gear 32 when it rotates.

In the matching relationship between the crankset 4 and the planetary gear train 3, a plane bearing 42 is also provided to reduce the friction between the contact planes. In this embodiment, two plane bearings are provided. For example, as shown in FIG. 2, because a shoulder 14 protruding in the radial direction of the shaft is provided on the central shaft 1, the shoulder 14 is used for positioning and fixing the planetary gear train 3. Therefore, the planet carrier 33 can be welded to the shoulder 14. A plane bearing A is arranged between the shoulder 14 and the sun gear 31 to reduce friction, and a plane bearing B is also arranged on the other side of the shoulder 14 to reduce the left side of the planet carrier 33 and the chainring. 4 corresponds to the friction between the surfaces.

The above-mentioned transmission and coordination structure can realize multiple power supply modes, and finally combine the system control mode to achieve different operating states of the electric bicycle.

Example 2

According to the aforementioned transmission principle, the rotation of the crankset 4 and the rotor 21 will be combined into a variety of output results. In each output result, the rotor speed, rotor rotation, bottom shaft rotation speed, and bottom shaft rotation have different corresponding states with the crankset.

The following is based on the output direction of the chain ring 4, if the output is the forward direction, the chain ring 4 will rotate in the forward direction. Explain the output results based on this condition:

1. Pure electric driving state:

The motor 2 rotates in the reverse direction, the rotor 21 and the rotor shaft 211 rotate in the reverse direction, the sun gear 31 rotates in the reverse direction, the planetary gear 32 rotates in the forward direction, the internal gear 41 rotates in the forward direction, and the chain ring 4 rotates in the forward direction. Motor 2 is in the output state at this time. (On the contrary, there is a reverse mode)

2. Fitness status of human riding:

The middle shaft 1 rotates in the positive direction, the planet carrier 33 rotates in the positive direction, the motor 2 does not rotate, the rotor shaft 211 does not rotate, the sun gear 31 does not rotate, the planetary gear 32 and the internal gear 41 rotate in the positive direction, and the chain ring 4 rotates in the positive direction. . Motor 2 has no output at this time.

3. Charging status of human riding:

The middle shaft 1 rotates in the forward direction, the planet carrier 33 rotates in the forward direction, the chain ring 4 rotates at a low speed, the internal gear 41 rotates at a low speed, the planetary gear 32 rotates in the reverse direction, the sun gear 31 rotates in the forward direction, and the rotor shaft 211 rotates in the forward direction. At this time, the motor 2 is in charging mode.

4. Indoor fitness charging status:

The center shaft 1 rotates in the forward direction, the planet carrier 33 rotates in the forward direction, the chain ring 4 does not rotate, the internal gear 41 does not rotate, the planet gear 32 rotates in the reverse direction, the sun gear 31 rotates in the forward direction, and the rotor shaft 211 rotates in the forward direction. At this time, the motor 2 is also in charging mode.

5. Acceleration state of combined power:

The motor 2 rotates in the reverse direction, the rotor 21 and the rotor shaft 211 rotate in the reverse direction, the sun gear 31 rotates in the reverse direction, and the planet gear 32 rotates in the forward direction. At this time, the middle shaft 1 rotates in the forward direction, and the planet carrier 33 rotates in the forward direction to accelerate the internal gear 41 Rotate, thereby accelerating the rotation of the chain ring 4. At this time, the motor 2 consumes low power.

6. The walking state of combined power:

The motor 2 rotates in the forward direction, the rotor 21 and the rotor shaft 211 rotate in the forward direction, the sun gear 31 rotates in the forward direction, and the planet gear 32 rotates in the reverse direction. At this time, the middle shaft 1 rotates in the forward direction, and the planet carrier 33 rotates in the forward direction to slow down the internal gear. 41 rotates, thereby reducing the rotation of the chain ring 4. At this time, the motor 2 consumes low power.

7. The inertia recovery is converted to the electric energy state:

The car moves forward with inertia, so the chainring rotates forward with it. At this time, the middle shaft does not rotate, the internal gear rotates forward with the chainring, the planetary gear rotates forward, the sun gear rotates in the reverse direction, and the rotor shaft rotates in the reverse direction. , The motor enters the power generation mode, that is, the inertia recovery state.

Example 3

According to the above-mentioned transmission principle and structural arrangement relationship, the central transmission assembly of the electric bicycle power also includes a sensor for sensing the rotation force parameter. The sensors are mainly distributed on the central shaft and the rotor shaft to sense the speed and steering of the central shaft and the speed and steering of the rotor shaft respectively.

The following table shows each output state corresponding to the rotation parameters of the central shaft and the rotation of the rotor shaft:

Based on the sensor's sensing, corresponding to different sensing results, it can provide parameter feedback for the operating system, so that the user can switch to an appropriate exercise state.

Example 4

In this implementation, the motor 2 uses a three-phase permanent magnet synchronous motor. Based on its characteristics, sine wave parameters can be obtained when the rotation parameters are sensed. The corresponding control system achieves more precise control results through "resolver conditions". Therefore, the sensors in this embodiment all use resolvers. Compared with ordinary sensors, the effect of the resolver is that the “sine wave parameters” can be converted by the control system into output results that are easy for users to understand. For example, the resolver 5 on the central axis can obtain the parameters of human pedaling. Thereby converted into calories consumed. Through the resolver 6 on the rotor shaft, the output stability of the motor 2 can be obtained, which can be converted into accurate energy consumption prompts and so on.

For example, the following table is an example of output using resolver:

Resolver position	Get parameters	Solved value	Output situation
Bottom axis	50 rpm	+	Riding 1 hour consumes 1000 kcal
Rotor shaft	750 rpm	-	Riding for 1 hour consumes 8% of electricity

Example 5

This embodiment records an electric vehicle adopting an electric bicycle power transmission assembly, which is based on the structure in Embodiment 1 and cooperates with the sensing structure in Embodiment 3.

The electric vehicle includes a vehicle body, wheels, and an electric bicycle power central transmission assembly. The electric bicycle power central transmission assembly is installed in the middle of the vehicle body.

The power transmission assembly of the electric bicycle includes: a three-phase permanent magnet synchronous motor, a central shaft 1, a chainring 4, a planetary gear train 3, and a resolver. The two ends of the bottom bracket 1 are fitted with pedals through tooth patterns. The rotor of the three-phase permanent magnet synchronous motor is transmitted to the chain ring 4 through the planetary gear train 3, and the bottom bracket 1 is also transmitted to the chain ring 4 through the planetary gear train 3.

When the three-phase permanent magnet synchronous motor is driven, the sun gear 31 is mainly used for transmission. The sun gear 31 transmits the rotational force to the planetary gear 32. If the movement state of the planet carrier 33 is not considered at this time, the planetary gear 32 is driven by the chain ring 4 The upper internal gear 41 drives the chain ring 4 to rotate, and the chain ring 4 transmits the rotating force to the rear flywheel through the chain.

During pedal transmission, the transmission is mainly carried out by the rotation of the planet carrier 33. The planet carrier 33 rotates. At this time, there are two situations: if the sun gear 31 does not rotate, the motor does not rotate. Because of the gear 41, the chain ring 4 sends rotation, and the chain ring 4 transmits power to the rear flywheel. If the internal gear 41 does not rotate, that is, the chain ring 4 does not rotate, the planet carrier 33 rotates to cause the planet gear 32 to drive the sun gear 31 to rotate, and the sun gear 31 transmits power to the rotor shaft 211 for generating electricity.

Then, based on the second embodiment, the electric bicycle combined with the control system to control the speed of the motor can divide the use state of the electric bicycle into multiple modes. Take the "pure electric mode" as an example to illustrate the output speed between the motor and the crank ratio.

In this embodiment, the speed ratio between the motor and the crankset is 15:1, that is, 15 revolutions per minute of the motor = 1 revolution per minute of the crankset. The speed ratio of the crankset to the rear flywheel is 1:2, that is, 1 revolution/minute of the crankset = 2 revolutions/minute of the rear flywheel.

The motor takes a three-phase permanent magnet synchronous motor as an example. The output of the motor at a frequency of 50Hz is 750 revolutions per minute. Therefore, based on the above speed ratio conversion, the speed of the chainring is 50 revolutions per minute and the speed of the rear flywheel is 100 Revolutions per minute. If the rear wheel is 24 inches in size, the circumference of the rear wheel is about 1.9 meters, so it can travel 190 meters per minute at a speed of 11.4 kilometers per hour.

Based on the above speed ratio and conversion method, different driving speeds can be reached by adjusting the output power of the motor, as shown in the following table:

Serial number	Motor frequency	Motor speed	Exercise speed
1	5Hz	75 rpm	1.1km/h
2	20Hz	300 rpm	4.5km/h
3	50Hz	750 rpm	11.4km/h
4	80Hz	1200 rpm	18.2km/h
5	200Hz	3000 rpm	45.6km/h
6	400Hz	6000 rpm	91.2km/h

To sum up, the electric bicycle power transmission assembly and electric vehicle described in this solution have a lot of advantages. First of all, its transmission principle determines its layout. The central layout can greatly optimize the structural size, reduce the weight of the car body, and save energy. Secondly, the coaxial arrangement can directly transmit kinetic energy to the wheels, the additional loss in the power transmission process is greatly reduced, and the transmission response is more direct. Third, in the coordination of the transmission, the power "disengagement", "mixing" and "combination" are mainly realized by the specific connection relationship and the matching method of the planetary gear train. No additional clutch structure is needed, so the structure can be further optimized, the size can be reduced, and the number of accessories can be reduced.

The above-mentioned embodiments only exemplarily illustrate the principles and effects of the present invention, and are not used to limit the present invention. Anyone familiar with this technology can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea of the present invention should still be covered by the claims of the present invention.

Claims (13)

1. The power transmission assembly of an electric bicycle includes: a motor (2) with a horizontally arranged rotor shaft (211), a chain ring (4) that transmits power to the wheels, and a central shaft ( 1); The motor (2) includes a stator and a rotor; characterized in that:

   It also includes a sun gear (31) with a coaxial floating sleeve on the central shaft (1), a planet carrier (33) linked with the central shaft, passing through the planet carrier (33) and meshing with the sun gear (31) Planetary gear (32);

   The rotor shaft (211) is coaxially floated on the central shaft (1) through the through hole of the shaft center; and the rotor shaft (211) is linked with the sun gear (31);

   The crankset (4) is coaxially floated on the central shaft (1), and the crankset (4) meshes with the planetary gear (32) through an internal gear (41);

   The rotor shaft (211) drives the planetary gear (32) to rotate and output, and the middle shaft (1) changes the rotation output of the planetary gear (32) by rotating the planet carrier (33).
2. The electric bicycle power transmission assembly according to claim 1, characterized in that: the relative rotation state of the rotor shaft (211) and the central shaft (1) makes the chainring (4) Generate multiple output modes.
3. The power transmission assembly for an electric bicycle according to claim 2, wherein the rotation state of the rotor shaft (211) is controlled by the magnetic field parameters of the motor (2).
4. The central power transmission assembly of an electric bicycle according to claim 1 or 3, characterized in that: on the central shaft (1), or on the rotor shaft (211), or on the central shaft (1) and the rotor shaft On (211), a sensor for sensing shaft rotation parameters is provided.
5. The power transmission assembly for an electric bicycle according to claim 2, wherein the first sensor and the second sensor are resolvers.
6. The central power transmission assembly of an electric bicycle according to claim 3, characterized in that: the crankset (4) and the rotor are provided with a rotation speed ratio.
7. The central power transmission assembly of an electric bicycle according to claim 1 or 6, characterized in that the outer surface of the sun gear (31) includes: a transmission tooth surface area and a transmission connection area.
8. The electric bicycle power transmission assembly according to claim 7, characterized in that: the transmission connection area includes a spline groove (311) opened in the axial direction; the inner surface of the through hole of the rotor shaft (211) is also A spline (312) matching the spline groove is provided.
9. The central power transmission assembly of an electric bicycle according to claim 8, characterized in that: the central shaft (1) is provided with a shaft shoulder (14) for fixing the planet carrier (33).
10. The central power transmission assembly of an electric bicycle according to claim 9, characterized in that a plane bearing is arranged between the shaft shoulder (14) and the end surface of the sun gear (31) to reduce friction.
11. The electric bicycle power transmission assembly according to claim 10, characterized in that: a plane bearing is also provided between the chain ring (4) and the planet carrier (33) to reduce the friction between the planes .
12. The power transmission assembly for an electric bicycle according to claim 11, characterized in that: the crankset (4) and the rotor shaft (211) are respectively connected to the center shaft (1) through corresponding bearing parts. Keep rotating support.
13. An electric bicycle comprising a vehicle body and wheels, wherein the vehicle body is provided with the electric bicycle power central transmission assembly according to any one of the above claims 1-12.

Images