CN119428943A

CN119428943A - Mid-mounted motor system with built-in speed change, working method and vehicle

Info

Publication number: CN119428943A
Application number: CN202411800068.8A
Authority: CN
Inventors: 黄洪岳; 舒伟方; 杨�一
Original assignee: Aneida Drive Technology Shanghai Co ltd
Current assignee: Aneida Drive Technology Shanghai Co ltd
Priority date: 2024-12-09
Filing date: 2024-12-09
Publication date: 2025-02-14

Abstract

The invention provides a built-in speed-changing middle motor system, a working method and a vehicle, which comprise that a BB shaft is in transmission connection with a main output shaft through a first transmission device, a detection device detects rotation of the BB shaft and generates an electric signal to be transmitted to a controller, the controller controls the motor to be started or shut down, the motor is in transmission connection with the main output shaft through a first speed reduction device and in transmission connection with a second speed reduction device respectively, the speed reduction ratio of the first speed reduction device is different from that of the second speed reduction device, the motor is started under the action of the controller, the motor is in transmission connection with the main output shaft through the first speed reduction device, and the motor is switched to be in transmission connection with the main output shaft through the second speed reduction device according to any one parameter or a plurality of parameters of the rotation speed of the motor, the rotation speed of the BB shaft and the vehicle speed. The pedal frequency can be stabilized in a certain interval, frequent manual gear shifting is not needed, the driving safety is improved, and the riding comfort level is improved.

Description

Built-in variable speed middle motor system, working method and vehicle

Technical Field

The invention relates to the technical field of vehicle assistance, in particular to a built-in variable speed central motor system, a working method and a vehicle.

Background

The utility model provides a booster bicycle, is a novel two-wheeled vehicle, belongs to one kind of bicycle to the battery is as auxiliary power source, disposes the motor to possess power auxiliary system, can realize the novel vehicle of manpower riding and motor helping hand integration.

In the field of booster bicycles, the motor mounting position is mainly divided into two types, one is a centrally-mounted motor, namely a motor mounted in the middle position of a vehicle body, namely a five-way position, and is called a centrally-mounted motor. The middle motor is connected with the frame and is connected with the rear wheel through a chain to transmit power, pedals are arranged on two sides of the motor, and under the condition that the motor does not have a power supply, a rider can ride by the pedals, so that the resistance is not different from that of a normal bicycle.

The other is mounted in the hub of a bicycle, called the hub motor. Compared with the hub motor, the middle motor has larger advantages in the aspects of technology, performance and the like.

At present, most of bicycle speed changes are step-variable speed changes, gear positions are required to be frequently switched in the speed change process, the speed difference between each gear position is large, and the excessive speed difference can bring poor riding feeling in the speed change process, so that the problem of improvement exists.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a built-in variable speed central motor system and a vehicle.

The built-in speed-changing middle motor system and vehicle provided by the invention comprise a BB shaft, a main output shaft, a first transmission device, a detection device, a controller, a motor, a first speed reduction device and a second speed reduction device, wherein the BB shaft is in transmission connection with the main output shaft through the first transmission device, the detection device detects rotation of the BB shaft and generates an electric signal to be transmitted to the controller, the controller controls the motor to be started or shut down, the motor is in transmission connection with the main output shaft through the first speed reduction device, the second speed reduction device is in transmission connection with the main output shaft, the speed reduction ratio of the first speed reduction device is different from the speed reduction ratio of the second speed reduction device, the motor is started under the action of the controller, and the motor is switched to be in transmission connection with the main output shaft according to any one or more parameters of the rotation speed of the motor, the rotation speed of the BB shaft and the vehicle speed.

Preferably, the first transmission device comprises a ratchet pawl, a planetary carrier and a first clutch, wherein the BB shaft is in transmission connection with the planetary carrier through the ratchet pawl, and the planetary carrier is in transmission connection with the main output shaft through the first clutch.

Preferably, the first speed reducing device comprises a triple gear and a single-connection planetary gear, an output shaft of the motor is connected with a first gear transmission of the triple gear through a gear structure, the single-connection planetary gear is connected with a second gear transmission of the triple gear, the single-connection planetary gear is connected with a main output shaft in a transmission mode, and the single-connection planetary gear is connected with the shell through a second clutch.

Preferably, the second reduction gear comprises a triple gear and a double planetary gear, the output shaft of the motor is connected with the first gear of the triple gear through a gear structure, the first gear of the double planetary gear is connected with the third gear of the triple gear, the second gear of the double planetary gear is connected with the main output shaft in a transmission manner, and the double planetary gear is connected with the planet carrier.

Preferably, a triple gear, a single planetary gear, a double planetary gear and a second clutch are arranged between the output shaft and the main output shaft of the motor;

The output shaft of the motor is in transmission connection with the first gear of the triple gear through a gear structure, the single-linkage planetary gear is in transmission connection with the second gear of the triple gear and the main output shaft, and the single-linkage planetary gear is connected with the shell through a second clutch;

The first gear of the double planetary gear is in transmission connection with the third gear of the triple gear, the second gear of the double planetary gear is in transmission connection with the main output shaft, and the double planetary gear is connected with the planetary support;

the reduction ratio of the single-linkage planet gear to the second gear of the triple gear is a fixed reduction ratio, and the reduction ratio of the double-linkage planet gear to the third gear of the triple gear is a variable reduction ratio.

Preferably, the detection means are arranged on the BB axis or on the crank or on the housing.

According to the working method of the built-in variable speed central motor system provided by the invention, the working method comprises the following steps:

BB shaft rotates and drives the main output shaft to rotate through the first transmission device;

The detection device detects BB axis rotation to generate an electric signal and transmits the electric signal to the controller, the controller controls the motor to start, and the motor drives the main output shaft to rotate through the first speed reduction device;

The BB axis stops rotating, the detection device does not generate an electric signal, the controller controls the motor to be closed, and the system is restored to an initial state.

When any one or more parameters of the rotating speed of the motor, the rotating speed of the BB shaft and the vehicle speed reach a first threshold value, the motor drives the main output shaft to rotate through the second speed reduction device;

when any one or more parameters of the rotating speed of the motor, the rotating speed of the BB shaft and the vehicle speed reach a threshold value, the motor drives the main output shaft to rotate through the second speed reduction device;

When any one or more parameters of the rotating speed of the motor, the rotating speed of the BB shaft and the vehicle speed reach a second threshold value, the first transmission device is disconnected with the main output shaft;

The BB shaft stops rotating, the detection device does not generate an electric signal, the controller controls the motor to be closed, the first transmission device is communicated with the main output shaft, the first reduction device is used for communicating the motor with the main output shaft, and the system is restored to an initial state.

The vehicle provided by the invention further comprises a frame, a front wheel and a rear wheel, wherein the central motor system is arranged on the frame, foot pedals are arranged at two ends of the BB shaft, a toothed disc is coaxially and fixedly arranged on the main output shaft, a flywheel is coaxially and fixedly arranged on the rear wheel, and the toothed disc is in transmission connection with the flywheel through a chain or a belt.

Compared with the prior art, the invention has the following beneficial effects:

1. The invention realizes different speed output by changing the meshing state of the planetary gears, can stabilize the pedal frequency in a certain interval without frequent manual gear shifting, improves the driving safety, can keep certain pedal frequency no matter in a high-speed state of flat road riding or in a low-speed state during climbing, and is beneficial to improving the riding comfort level.

Drawings

Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram of the overall structure of a central motor system embodying the present invention;

FIG. 2 is a schematic diagram of the present invention primarily embodying the integration of a torque sensor on the BB axis;

FIG. 3 is a schematic view of a strain gauge embodying the present invention attached to the BB axis;

FIG. 4 is a schematic illustration of the attachment of strain gages to a crank in accordance with the present invention;

fig. 5 is a schematic view of the installation of a center motor system on a vehicle embodying the present invention.

The figure shows:

First clutch 11 of transmission 1

Main output shaft 12 of triple gear 2

BB axis 3 foot pedal 13

Housing 4 crank 14

Single-linkage planet wheel 5 tooth disc 15

Second clutch 6 chain 16

Flywheel 17 of duplex planet wheel 7

Detection device 8 controller 18

Ratchet pawl 9 motor 19

Planet carrier 10

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.

As shown in fig. 1, the built-in variable speed central motor system provided by the invention comprises a shell 4, a BB shaft 3, a main output shaft 12, a first transmission device, a detection device 8, a controller 18, a motor 19, a first clutch 11, a second clutch 6, a first speed reducer and a second speed reducer.

The BB shaft 3, the main output shaft 12, the first transmission, the first reduction gear, the second reduction gear, the first clutch 11, and the second clutch 6 are disposed in the housing 4, the motor 19 is disposed inside or outside the housing 4, the controller 18 is disposed inside or outside the housing 4, and the detection device 8 is disposed inside or outside the housing 4.

The BB shaft 3 is in driving connection with the main output shaft 12 via a first transmission. The detecting device 8 detects the rotation of the BB axis 3 and generates an electric signal to be sent to the controller 18, and the controller 18 controls the motor 19 to be started or shut down. The motor 19 is in transmission connection with the main output shaft 12 through a first speed reduction device, and the second speed reduction device is in transmission connection with the main output shaft 12, and the speed reduction ratio of the first speed reduction device is different from that of the second speed reduction device. Under the action of the controller 18, the motor 19 is started, the motor 19 is in transmission connection with the main output shaft 12 through the first speed reduction device, and the motor 19 is switched to the second speed reduction device to be in transmission connection with the main output shaft 12 according to any one or more parameters of the rotation speed of the motor 19, the rotation speed of the BB shaft 3 and the vehicle speed.

It should be noted that the switching between the first speed reducer and the second speed reducer may be determined by the rotation speed of the motor 19, for example, when the rotation speed of the motor 19 reaches the first threshold, the transmission structure between the motor 19 and the main output shaft 12 is switched from the first speed reducer to the second speed reducer. The rotation speed of the BB axis 3 may be determined, or the vehicle speed may be determined. Of course, in yet another possible embodiment, it may be determined by any two parameters or three parameters together. The core of the technical scheme of the application is that the two sets of deceleration routes are provided, and the switching of the two sets of deceleration routes can be regulated and controlled by the controller 18.

Specifically, the first transmission device includes a ratchet pawl 9, a planetary carrier 10, and a first clutch 11, the bb shaft 3 is in transmission connection with the planetary carrier 10 through the ratchet pawl 9, and the planetary carrier 10 is in transmission connection with a main output shaft 12 through the first clutch 11.

The first speed reducer comprises a triple gear 2 and a single-linkage planetary gear 5, an output shaft of a motor 19 is connected with a first gear transmission of the triple gear 2 through a gear structure 1, the single-linkage planetary gear 5 is connected with a second gear transmission of the triple gear 2, the single-linkage planetary gear 5 is connected with a main output shaft 12 in a transmission manner, and the single-linkage planetary gear 5 is connected with a shell 4 through a second clutch 6.

The second reduction gear comprises a triple gear 2 and a duplex planetary gear 7, an output shaft of a motor 19 is connected with a first gear of the triple gear 2 through a gear structure 1, a first gear of the duplex planetary gear 7 is connected with a third gear of the triple gear 2 in a transmission manner, a second gear of the duplex planetary gear 7 is connected with a main output shaft 12 in a transmission manner, and the duplex planetary gear 7 is fixedly connected with a planetary support 10 through a bearing or a sleeve.

It should be noted that the first speed reducer and the second speed reducer of the present application may be of an integral design or a split design, and the integral design is that the first speed reducer and the second speed reducer are two sets of completely independent devices. The application preferably adopts the first speed reducer and the second speed reducer which are integrally designed, and on a transmission line, the first speed reducer and the second speed reducer share the motor 19, the gear structure 1 and the triple gear 2, so that the number of parts of the whole motor system is reduced, the volume of the motor system is reduced, and the integration level of the motor system is improved.

In a preferred embodiment, the first reduction gear and the second reduction gear are of unitary design:

A triple gear 2, a single planetary gear 5, a double planetary gear 7 and a second clutch 6 are arranged between the output shaft of the motor 19 and the main output shaft 12. The output shaft of the motor 19 is in transmission connection with the first gear of the triple gear 2 through the gear structure 1, the single-linkage planetary gear 5 is in transmission connection with the second gear of the triple gear 2 and the main output shaft 12, and the single-linkage planetary gear 5 is connected with the shell 4 through the second clutch 6. The first gear of the double planetary gear 7 is in transmission connection with the third gear of the triple gear 2, the second gear of the double planetary gear 7 is in transmission connection with the main output shaft 12, and the double planetary gear 7 is fixedly connected with the planetary carrier 10 through a bearing or a sleeve. The reduction ratio of the single-link planet wheel 5 and the second gear of the triple gear 2 is a fixed reduction ratio, and the reduction ratio of the double-link planet wheel 7 and the third gear of the triple gear 2 is a variable reduction ratio.

As shown in fig. 2,3 and 4, the detection device 8 according to the present application may be disposed inside the housing 4 or may be disposed outside the housing 4. Specifically, the detection device 8 is disposed on the BB shaft 3 or on the crank 14 or on the housing 4.

In a possible embodiment, the detection device 8 may be a torque sensor, which is integrated on the BB axis 3, and the torque and the tread frequency signal may be detected integrally, or may be detected separately, or may be detected only by the tread frequency signal. It should be noted that, the technical scheme of the application can also adopt the pedal frequency sensor to detect the pedal frequency signal. The pedal frequency sensor can also adopt an external split type sensor.

In another possible embodiment, the detection means 8 may be a strain gauge, which may be attached to the BB-axis 3 or to the crank 14. It should be emphasized that the detection device 8 according to the present application may be any detection device 8 capable of acquiring any one or more of a pedal frequency signal, a rotation speed signal of the motor 19, and a vehicle speed signal in the prior art.

The first clutch 11 and the second clutch 6 of the present application are overrunning clutches. When the first reduction gear connects the motor 19 and the main output shaft 12 in a transmission manner, a fixed reduction ratio is provided between the motor 19 and the main output shaft 12. When the second reduction gear connects the motor 19 and the main output shaft 12 in a driving way, a variable reduction ratio is formed between the motor 19 and the main output shaft 12.

The invention provides a working method of a built-in variable speed central motor system, which comprises the following steps:

The BB shaft 3 rotates and drives the main output shaft 12 to rotate through a first transmission device;

The detection device 8 detects that the BB shaft 3 rotates to generate an electric signal and transmits the electric signal to the controller 18, the controller 18 controls the motor 19 to start, and the motor 19 drives the main output shaft 12 to rotate through the first speed reduction device;

the BB axis 3 stops rotating, the detection device 8 does not generate an electric signal, the controller 18 controls the motor 19 to be turned off, and the system is restored to an initial state.

when any one or more parameters of the rotation speed of the motor 19, the rotation speed of the BB shaft 3 and the vehicle speed reach a first threshold value, the motor 19 drives the main output shaft 12 to rotate through a second speed reduction device;

when any one or more parameters of the rotation speed of the motor 19, the rotation speed of the BB shaft 3 and the vehicle speed reach a threshold value, the motor 19 drives the main output shaft 12 to rotate through a second speed reduction device;

when any one or more parameters of the rotation speed of the motor 19, the rotation speed of the BB shaft 3 and the vehicle speed reach a second threshold value, the first transmission device is disconnected from the main output shaft 12;

the BB shaft 3 stops rotating, the detection device 8 does not generate an electric signal, the controller 18 controls the motor 19 to be closed, the first transmission device is communicated with the main output shaft 12, the first reduction device is used for communicating the motor 19 with the main output shaft 12, and the system is restored to an initial state.

As shown in fig. 5, the vehicle according to the present invention further comprises a frame, a front wheel and a rear wheel, wherein the central motor system is mounted on the frame, the two ends of the BB shaft 3 are respectively provided with a pedal 13 through a crank 14, the main output shaft 12 is coaxially and fixedly provided with a toothed disc 15, the rear wheel is coaxially and fixedly provided with a flywheel 17, and the toothed disc 15 and the flywheel 17 are in transmission connection through a chain 16 or a belt. The flywheel 17 and the toothed disc 15 are of a fixed reduction ratio.

Principle of operation

Specifically, when the motor 19 is not in operation, the pedaling torque is transmitted through the BB shaft 3, the torque sensor, the ratchet pawl 9, the planetary carrier 10, the first clutch 11K2, and the output shaft. The chain wheel 15 is fixed on the output shaft, so that the chain wheel 15 is driven to rotate together, and the chain wheel 15 drives the flywheel 17 through the chain 16 or the belt, so that the bicycle starts riding. This state is a purely manual state, and the reduction ratio is a fixed reduction ratio between the dental tray 15 and the flywheel 17.

When the motor 19 works, the pedal torque drives the torque sleeve through the BB shaft 3 to enable the detection device 8, namely the torque sensor generates an electric signal, the controller 18 receives the signal to start the motor 19, the motor 19 starts to work, the power of the motor 19 is transmitted to the triple gear 2 through the transmission mechanism, because the single-linkage planetary gear 5 is fixed on the shell 4 through the second clutch 6, at the moment, a large fixed reduction ratio exists among the triple gear 2, the single-linkage planetary gear 5 and the main output shaft 12, and the torque sleeve has large torque output and is suitable for working conditions when the vehicle starts or climbs. When the pedal torque signal is continuously generated, the motor 19 starts to accelerate, when the speed reaches a certain value, the second clutch 6 is disconnected, at the moment, no power is transmitted among the triple gear 2, the single-linkage planetary gear 5 and the main output shaft 12, and the power is mainly transmitted through the triple gear 2, the double-linkage planetary gear 7 and the main output shaft 12, so that the path reduction ratio is small, and further, a larger output speed is realized, and the vehicle enters a high-speed mode and becomes a variable reduction ratio at the moment. When the speed further reaches a certain value, the main output shaft 12 rotates together with the planetary carrier 10 through the first clutch 11, and when the pedal frequency does not keep up with the rotating speed of the planetary carrier 10, the torque sensor can not receive the pedal torque, no signal is generated, the motor 19 stops working, the high-speed state can not be sustained, at the moment, the first clutch 11 is required to be disconnected, the planetary carrier 10 stops rotating, the pedal torque continuously acts on the torque sleeve to generate a torque signal, and the high-speed output of the motor 19 is maintained. When the riding is completed, the pedal torque is stopped, the torque sensor does not generate any electric signal, the controller 18 does not start the motor 19 any more, the motor 19 stops working, the vehicle speed starts to drop, the first clutch 11 is switched on, the second clutch 6 is switched on after the speed is further reduced, the speed change mechanism resumes the low speed mode until the vehicle speed is reduced to zero, and the whole riding is finished. The mechanism has the advantages that no matter in a high-speed state of flat road riding or in a low-speed state of climbing, certain pedal frequency can be kept, and comfortable and stable riding experience is provided for a rider. The application realizes different speed output by changing the meshing state of the planetary gears, can stabilize the pedal frequency in a certain interval, does not need frequent manual gear shifting, and improves the driving safety.

In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.

The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.

Claims

1. The built-in speed-changing middle motor system is characterized by comprising a BB shaft (3), a main output shaft (12), a first transmission device, a detection device (8), a controller (18), a motor (19), a first speed reduction device and a second speed reduction device;

the BB shaft (3) is in transmission connection with the main output shaft (12) through a first transmission device;

The detection device (8) detects the rotation of the BB shaft (3) and generates an electric signal to be transmitted to the controller (18), and the controller (18) controls the motor (19) to be started or closed;

The motor (19) is respectively connected with the main output shaft (12) in a transmission way through a first speed reduction device, the second speed reduction device is connected with the main output shaft (12) in a transmission way, and the speed reduction ratio of the first speed reduction device is different from that of the second speed reduction device;

Under the action of the controller (18), the motor (19) is started, the motor (19) is in transmission connection with the main output shaft (12) through the first speed reduction device, and the motor (19) is switched to the second speed reduction device to be in transmission connection with the main output shaft (12) according to any one or more parameters of the rotating speed of the motor (19), the rotating speed of the BB shaft (3) and the vehicle speed.

2. The built-in variable speed mid-motor system according to claim 1, wherein the first transmission means comprises a ratchet pawl (9), a planetary carrier (10) and a first clutch (11), the BB shaft (3) is in driving connection with the planetary carrier (10) through the ratchet pawl (9), and the planetary carrier (10) is in driving connection with the main output shaft (12) through the first clutch (11).

3. The built-in variable-speed mid-motor system according to claim 1, wherein the first reduction gear comprises a triple gear (2) and a single-connection planetary gear (5), the output shaft of the motor (19) is in transmission connection with a first gear of the triple gear (2) through a gear structure (1), the single-connection planetary gear (5) is in transmission connection with a second gear of the triple gear (2), the single-connection planetary gear (5) is in transmission connection with a main output shaft (12), and the single-connection planetary gear (5) is in transmission connection with the housing (4) through a second clutch (6).

4. The built-in variable-speed mid-motor system according to claim 2, wherein the second reduction device comprises a triple gear (2) and a double planetary gear (7), the output shaft of the motor (19) is in transmission connection with a first gear of the triple gear (2) through a gear structure (1), the first gear of the double planetary gear (7) is in transmission connection with a third gear of the triple gear (2), a second gear of the double planetary gear (7) is in transmission connection with a main output shaft (12), and the double planetary gear (7) is connected with a planetary carrier (10).

5. The built-in variable speed mid-motor system according to claim 2, characterized in that a triple gear (2), a single planetary gear (5), a double planetary gear (7) and a second clutch (6) are arranged between the output shaft of the motor (19) and the main output shaft (12);

An output shaft of the motor (19) is in transmission connection with a first gear of the triple gear (2) through a gear structure (1), the single-linkage planetary gear (5) is in transmission connection with a second gear of the triple gear (2) and a main output shaft (12), and the single-linkage planetary gear (5) is connected with the shell (4) through a second clutch (6);

The first gear of the double planetary gear (7) is in transmission connection with the third gear of the triple gear (2), the second gear of the double planetary gear (7) is in transmission connection with the main output shaft (12), and the double planetary gear (7) is connected with the planetary support (10);

the reduction ratio of the single-linkage planet wheel (5) to the second gear of the triple gear (2) is a fixed reduction ratio, and the reduction ratio of the double-linkage planet wheel (7) to the third gear of the triple gear (2) is a variable reduction ratio.

6. Built-in variable speed mid-motor system according to claim 1, characterized in that the detection means (8) are arranged on the BB-axis (3) or on the crank (14) or on the housing (4).

7. A method of operating a built-in variable speed center motor system, characterized in that a built-in variable speed center motor system according to any one of claims 1-6 is used, comprising the steps of:

The BB shaft (3) rotates and drives the main output shaft (12) to rotate through the first transmission device;

The detection device (8) detects that the BB shaft (3) rotates to generate an electric signal and transmits the electric signal to the controller (18), the controller (18) controls the motor (19) to start, and the motor (19) drives the main output shaft (12) to rotate through the first speed reduction device;

The BB shaft (3) stops rotating, the detection device (8) does not generate an electric signal, the controller (18) controls the motor (19) to be closed, and the system is restored to an initial state.

8. A method of operating a built-in variable speed center motor system, characterized in that a built-in variable speed center motor system according to any one of claims 1-6 is used, comprising the steps of:

when any one or more parameters of the rotation speed of the motor (19), the rotation speed of the BB shaft (3) and the vehicle speed reach a first threshold value, the motor (19) drives the main output shaft (12) to rotate through a second speed reduction device;

9. A method of operating a built-in variable speed center motor system, characterized in that a built-in variable speed center motor system according to any one of claims 1-6 is used, comprising the steps of:

When any one or more parameters of the rotating speed of the motor (19), the rotating speed of the BB shaft (3) and the vehicle speed reach a threshold value, the motor (19) drives the main output shaft (12) to rotate through the second speed reduction device;

When any one or more parameters of the rotation speed of the motor (19), the rotation speed of the BB shaft (3) and the vehicle speed reach a second threshold value, the first transmission device is disconnected from the main output shaft (12);

The BB shaft (3) stops rotating, the detection device (8) does not generate an electric signal, the controller (18) controls the motor (19) to be closed, the first transmission device is communicated with the main output shaft (12), the first reduction device is used for communicating the motor (19) with the main output shaft (12), and the system is restored to an initial state.

10. A vehicle, characterized in that the built-in variable speed central motor system according to any one of claims 1-6 is adopted, the vehicle further comprises a frame, a front wheel and a rear wheel, the central motor (19) is installed on the frame, foot pedals (13) are arranged at two ends of the BB shaft (3), a toothed disc (15) is coaxially and fixedly installed on the main output shaft (12), a flywheel (17) is coaxially and fixedly installed on the rear wheel, and the toothed disc (15) is in transmission connection with the flywheel (17) through a chain (16) or a belt.