阅读说明：本技术 一种电动助力自行车用中轴力矩传感器 (Centre shaft torque sensor for electric power-assisted bicycle ) 是由 陈春富 黄佰凡 刘畅 刘欣 于 2019-08-21 设计创作，主要内容包括：本申请公开了一种电动助力自行车用中轴力矩传感器,包括信号放大电路板及器件和依次套设于中轴上的输出体、测力体、转动隔圈、施压体、压力传感器、承力体；测力体通过花键滑动连接于中轴上；轴向分力f直接作用于与外套固定于一体的非转动状态下的压力传感器上,在压力传感器上检测到与脚踏力值大小成比例关系的电信号并直接输出,并压力传感器部件仅受脚踏驱动链主回路的旁路分力,且只承受脚踏驱动力的1/10左右压力变化,使中轴传感器本身的结构得以简化、信号采集更加实时准确,可以很大程度上解决目前中轴力矩传感器本身复杂的技术应用和居高的成本以及装配调试的难度,延长了传感单元的使用寿命且更易于产业化推广。(The application discloses a middle shaft torque sensor for an electric power-assisted bicycle, which comprises a signal amplification circuit board, a device, an output body, a force measuring body, a rotating space ring, a pressure applying body, a pressure sensor and a force bearing body, wherein the output body, the force measuring body, the rotating space ring, the pressure applying body, the pressure sensor and the force bearing body are sequentially sleeved on a middle shaft; the force measuring body is connected to the middle shaft in a sliding manner through a spline; the axial component force f directly acts on the pressure sensor which is fixed with the outer sleeve in a non-rotating state, an electric signal which is in a proportional relation with the pedal force value is detected on the pressure sensor and is directly output, and the pressure sensor part is only subjected to the bypass component force of the main loop of the pedal driving chain and only bears about 1/10 pressure change of the pedal driving force, so that the structure of the middle shaft sensor is simplified, the signal acquisition is more real-time and accurate, the complex technical application, high cost and difficulty in assembly and debugging of the existing middle shaft torque sensor can be solved to a great extent, the service life of the sensing unit is prolonged, and the industrial popularization is easier.)

1. A middle shaft torque sensor for an electric power-assisted bicycle is characterized by comprising a signal amplification circuit board, a device, an output body, a force measuring body, a rotating space ring, a pressure applying body, a pressure sensor and a force bearing body, wherein the output body, the force measuring body, the rotating space ring, the pressure applying body, the pressure sensor and the force bearing body are sequentially sleeved on a middle shaft; the force measuring body is connected to the middle shaft in a sliding manner through a spline; the pedal driving torque formed by the pedal force F on the middle shaft is transmitted to the output body through the force measuring body; the output body is equipped with the equidistance of equant and decides the angle inclined plane, pedal force produces axial component force f on the dynamometry body to it has the left slip trend to order about the dynamometry body, axial component force is through rotating the spacer ring, exert the pressure body and act on pressure sensor, and pressure sensor and signal amplification circuit board and device are fixed in on the bearing body, axial component force produces on pressure sensor and is handled to signal amplification circuit board and device with pedal force is the power/electric conversion signal output of linear relation.

2. The bottom bracket axle torque sensor for an electric bicycle according to claim 1, further comprising a reset elastic body disposed between the pressure applying body and the force bearing body for ensuring the pressure sensor to be in a mechanical reset origin state and maintain zero output when the pedal force is removed.

3. The bottom bracket axle torque sensor for an electric bicycle according to claim 2, wherein the reset elastic body is a rubber body.

4. The bottom bracket axle torque sensor for an electric power assisted bicycle according to claim 1, wherein the linear relationship is:

wherein F R ═ F'. R,the length of the crank R, the distance between the center line of the R inclined plane and the center line of the middle shaft, the included angle between the alpha inclined plane and the center line of the middle shaft, the driving force of the main loop, the component force of the F 'perpendicular to the inclined plane, the component force of the F' parallel to the center line of the middle shaft, R, R and alpha are fixed values.

5. The middle axle torque sensor for the electric power-assisted bicycle according to claim 1, wherein the middle axle torque sensor is fixed in a five-way tube of the electric power-assisted bicycle through a left lock nut and a right lock nut, a spline is arranged at the right end of the output body, a special bicycle chain wheel is connected with the spline, and the special bicycle chain wheel is locked by the chain wheel lock nut.

6. The torque sensor as claimed in claim 1, wherein the bottom bracket axle is slidably connected to the force-measuring body by a spline.

7. The bottom bracket torque sensor for an electric power assisted bicycle according to claim 1, further comprising a magnetic pole ring and a bracket coupled to the bottom bracket for rotation, wherein the signal amplification circuit board and the device are provided with a switch hall sensor for detecting the forward and reverse rotation of the magnetic pole ring.

8. the bottom bracket axle torque sensor for an electric bicycle according to claim 7, wherein the motor output of the electric bicycle is performed as follows: when the pedal is forward, the same frequency pulse signal is output, and when the pedal is backward or stopped, the high level is output.

9. The torque sensor as defined in claim 8, wherein the motor outputs driving power according to the magnitude of the pedaling torque in a same ratio when pedaling in a forward direction, and is immediately turned off when pedaling is stopped or in a reverse direction.

10. The bottom bracket axle torque sensor for an electric power assisted bicycle according to claim 1, wherein the pressure sensor is a piezoelectric ceramic, a piezoelectric diaphragm or a resistance strain gauge, or detects the axial displacement by a linear hall sensor.

Technical Field

the application relates to the technical field of electric power-assisted bicycles, in particular to a middle shaft torque sensor for an electric power-assisted bicycle.

Background

in China, after a hub motor and a battery are additionally arranged on a bicycle, the power output of the motor is adjusted by controlling an electronic rotating handle by hands, so that the electric bicycle belongs to a motor vehicle. The electric power-assisted bicycle is characterized in that a motor is started only by stepping on a foot, the power is cut off when the foot is stopped, and the power-assisted power of the motor is changed along with the change of the stepping force, so that corresponding power support can be provided according to the stepping force of a rider, the riding burden of the rider is reduced, the riding comfort and the riding mileage are greatly increased, and the electric power-assisted bicycle is proportional power assistance, belongs to a non-motor vehicle and is safer to ride, and the key point is to accurately measure the stepping torque in real time. Therefore, the real-time and accurate detection technology for the pedal force of the electric power-assisted bicycle is very urgent and important in the field of electric bicycles.

At present, the following pedal force measurement solutions for electric power-assisted bicycles are probably available: 1. a dental disc type sensor; 2. a rear claw sensor; 3. a chain tension sensor; 4. a central axis sensor, etc. The central shaft type sensor, see fig. 9, generally detects the magnitude of the pedal moment by directly attaching a strain gauge to the central shaft or by attaching a strain gauge to an intermediate deformation body and attaching a strain gauge to the intermediate deformation body.

Because the electric power-assisted bicycle middle shaft torque sensor is a rotating working part, the strain gauge pasted on the middle shaft or pasted on the middle deformation body can be in a rotating state, and the problems of power supply for the strain gauge and strain signal output exist. Generally, a complex Bluetooth wireless communication technology or a mutual inductor is adopted to realize the output of a collected tiny electric signal in a motion state through a complex alternating current induction technology and then the subsequent amplification processing is carried out, so that the tiny change signal collected by a strain gauge is easily subjected to signal loss and interference in the process of wireless transmission or induction transmission, and the measurement precision of the sensor and the resilience of data are difficult to effectively ensure.

Furthermore, the problem that the moment signal is collected by using the middle shaft direct patch and the middle deformable body patch is inevitable is that the middle shaft and the middle deformable body exist in a main stress loop of a driving chain, the rotating torque transmitted by a strain foil patch area is 10 to 20 times of the pedal force, and the strain foil and the middle deformable body bear the large force of the main driving loop, so that the fatigue life of the strain foil and the middle deformable body is greatly tested.

Furthermore, the slight difference of the material structure of the middle shaft or the intermediate forming body and the consistency of the processing treatment, especially the heat treatment process, on the batch processed workpieces are difficult to be consistent, so that the middle shaft and the intermediate forming body of the sensor are easy to generate self deformation and reset errors when being driven by the main loop, and the industrial batch production is difficult to realize.

Disclosure of Invention

The invention provides a middle shaft torque sensor for an electric power-assisted bicycle, aiming at solving the technical problems that in the prior art, when pedal torque signals are collected, an electromechanical conversion structure is complex, the stability, reliability, consistency, anti-interference performance and origin reset performance of the collected signals are difficult to guarantee, a signal transmission processing circuit structure is complicated, a sensing unit of a non-contact middle shaft torque sensor exists in a main stress loop and is easy to damage, so that the long-time riding is not facilitated, and the like.

in order to achieve the purpose, the invention adopts the following technical scheme:

A middle shaft torque sensor for an electric power-assisted bicycle comprises a signal amplification circuit board, a device, an output body, a force measuring body, a rotating space ring, a pressure applying body, a pressure sensor and a force bearing body, wherein the output body, the force measuring body, the rotating space ring, the pressure applying body, the pressure sensor and the force bearing body are sequentially sleeved on a middle shaft; the force measuring body is connected to the middle shaft in a sliding manner through a spline; the pedal driving torque formed by the pedal force F on the middle shaft is transmitted to the output body through the force measuring body; the output body is equipped with the equidistance of equant and decides the angle inclined plane, pedal force produces axial component force f on the dynamometry body to it has the left slip trend to order about the dynamometry body, axial component force is through rotating the spacer ring, exert the pressure body and act on pressure sensor, and pressure sensor and signal amplification circuit board and device are fixed in on the bearing body, axial component force produces on pressure sensor and is handled to signal amplification circuit board and device with pedal force is the power/electric conversion signal output of linear relation.

Preferably, the middle shaft torque sensor further comprises a reset elastic body, the reset elastic body is arranged between the pressure applying body and the bearing body, and when the pedal force is removed, the pressure sensor is ensured to be in a mechanical reset original point state and keeps zero output.

preferably, the reset elastic body is a rubber body.

Preferably, the linear relationship is:

f＝f”*sinα＝F”*cosα*sinα＝F*(R/r)*cosα*sinα

in the formula, F R is F 'R, F is F'/cos alpha, the length of the crank R, the distance between the center line of the R inclined plane and the center line of the middle shaft, the included angle between the alpha inclined plane and the center line of the middle shaft, F 'drives the driving force of the main loop, F' is perpendicular to the component force of the inclined plane, F is parallel to the component force of the center line of the middle shaft, and R, R and alpha are constant values.

Preferably, the middle shaft torque sensor is fixed in a five-way pipe of the electric power-assisted bicycle through a left lock nut and a right lock nut, a spline is arranged at the right end of the output body, the special bicycle chain wheel is connected with the spline, and the special bicycle chain wheel is locked by the chain wheel lock nut.

preferably, the middle shaft and the force measuring body are in sliding connection through a spline.

Preferably, the middle shaft torque sensor further comprises a magnetic pole ring and a support which are connected with the middle shaft in a shaft rotating mode, the signal amplification circuit board and the device are provided with a switch hall sensor, and the switch hall sensor is used for detecting the forward and reverse rotating relation of the magnetic pole ring.

preferably, the motor output of the electric power-assisted bicycle is performed as follows: when the pedal is forward, the same frequency pulse signal is output, and when the pedal is backward or stopped, the high level is output.

Preferably, when the pedal is pedaled in the forward direction, the motor outputs driving power according to the same ratio of the driving torque of the pedal, and when the pedal is pedaled in the reverse direction or stopped, the driving power of the motor is immediately cut off.

Preferably, the pressure sensor uses piezoelectric ceramics, a piezoelectric diaphragm or a resistance strain gauge, or detects the axial displacement by a linear hall.

Has the advantages that: the invention provides a middle shaft torque sensor for an electric power-assisted bicycle, which directly converts pedal force F into axial component force F through slope connection, the axial component force F directly acts on a pressure sensor which is fixed with an outer sleeve into a whole and is in a non-rotating state, an electric signal which is in proportional relation with the pedal force value is detected on the pressure sensor and is directly output, a pressure sensor part is only subjected to the bypass component force of a main loop of a pedal driving chain and only bears about 1/10 pressure change of the pedal driving force, signal acquisition, conversion, transmission and amplification in a pressure acquisition unit are very concise and easy to process, the structure of the middle shaft torque sensor is simplified, the signal acquisition is more real-time and accurate, the problems of complex technical application, high cost and difficulty in assembly and debugging of the current middle shaft torque sensor can be solved to a great extent, the service life of the sensing unit is prolonged, and the industrial popularization is easier.

Drawings

the accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a schematic structural view of a bottom bracket axle torque sensor for an electric bicycle;

FIG. 2 is a schematic view of a spline sliding connection relationship between the middle shaft and the force measuring body;

FIG. 3 is a schematic diagram of the connection of equally-divided equidistant angled ramps between a force-measuring body and an output body;

FIG. 4 is a schematic view of the conversion of pedaling force into axial force components through a ramped connection;

FIG. 5 is a schematic view of a reset elastomer structure;

FIG. 6 is a schematic view of the linear relationship between pedaling force and axial force component;

FIG. 7 is a schematic block diagram of the circuitry within the signal amplification circuit board and device;

FIG. 8 is a schematic view of a pole ring configuration;

FIG. 9 is a prior art mid-axis sensor configuration.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, a bottom bracket moment sensor for an electric power-assisted bicycle according to an embodiment of the present invention includes a signal amplification circuit board, a device 8, and an output body 2, a force measuring body 3, a rotating spacer 4, a pressure applying body 5, a pressure sensor 6, and a force bearing body 7, which are sequentially sleeved on a bottom bracket. The axial torque sensor is fixed in a five-way tube of the electric power-assisted bicycle and locked through the left lock nut 9 and the right lock nut 17, a special bicycle chain wheel connected with the right end of the output body 2 through a spline is locked through the chain wheel lock nut, a left crank, a right crank, a pedal and a chain wheel are installed, and a rear wheel flywheel is provided with an equal-pitch chain, so that the most basic application scene of the torque sensor is realized.

Referring to fig. 2, when a riding power-assisted electric bicycle, a left or right pedal force F is applied to a pedal and transmitted to a central shaft 1 through a crank with a length L to form a manual pedal driving torque of the electric power-assisted bicycle on the central shaft, the central shaft 1 is in sliding connection with a force measuring body 3 through a spline, an equally-divided and equally-spaced angle-fixed inclined plane structure shown in fig. 3 is arranged between the force measuring body 3 and an output body 2, so that a main driving chain is formed, and the pedal driving torque formed on the central shaft 1 is transmitted to the output body 2 through the force measuring body 3 and transmitted to a rear wheel through a chain wheel to drive the bicycle to move forward.

Referring to fig. 4, due to the connection of the equally-divided and equally-spaced inclined planes between the force measuring body 3 and the output body 2, when a pedal force F is applied to the pedals of the manual pedal-driven bicycle, an axial component force F is generated on the force measuring body 3 and drives the force measuring body 3 to slide leftwards, the axial component force F detected on the force measuring body 3 acts on the pressure sensor 6 through the rotating spacer 4 and the pressing body 5, the pressure sensor 6 is fixed on the force bearing body 7, and the axial positioning of the force bearing body 7 is ensured to be stable and reliable, so that a force/electric conversion signal which is linearly related to the pedal driving force is generated on the pressure sensor 6 by the axial component force F and is output to the signal amplification processing circuit board and the device 8 for processing.

Referring to fig. 5, a reset elastic body 14 is arranged between the pressure applying body 5 and the bearing body 7, specifically, a rubber body can be adopted, when the pedal external force is withdrawn, the pressure applying body 5, the rotating space ring 4 and the force measuring body 3 are enabled to have a right reset trend through the reaction force of the prepressing force of the reset elastic body 14 so as to remove the axial component force f acting on the pressure sensor 6, the pressure sensor 6 is ensured to be in a mechanical reset original point state and keep zero output, and the realization of the technology ensures real-time and accurate detection and output of the pedal moment signal.

referring to fig. 6, the linear relationship between the pedaling force F and the detected axial force component F has the following formula: f ═ sin α ═ F ═ cos α ═ F ═ R (R/R) × (cos α) · sin α ═ F ═ R

In the formula, F is R, F is F/cos α, the length of the crank R, the distance between the center line of the R inclined plane and the center line of the middle shaft, the included angle between the α inclined plane and the center line of the middle shaft, F drives the driving force of the main loop, F is the component force perpendicular to the inclined plane, F is the component force parallel to the center line of the middle shaft, and since R, R and α are fixed values, (R/R) cos α sin α is K constant, and F is K F and F are F linear.

Referring to fig. 7, the pressure acquisition uses a pressure sensor to detect the magnitude of the dynamic force, but since the generated voltage signal is very small, a corresponding amplification circuit is required. Meanwhile, the pressure sensor is greatly influenced by the temperature, so that the temperature sensor is used for collecting the ambient temperature and then is corrected by software.

In one embodiment, the pressure sensor is made of piezoelectric ceramics, a piezoelectric diaphragm or a resistance strain gauge, and can also detect the axial displacement through a linear Hall.

Referring to fig. 8, for riding safety, the circuit board further includes two hall sensors for detecting the steering of the center shaft, that is, a magnetic pole ring is attached to the center shaft, the hall sensors generate pulse signals when the center shaft rotates, and forward rotation or reverse rotation is determined according to the two hall signals.

The middle shaft torque sensor structure of the embodiment of the invention designs and perfects the logic signal synchronous with the manual pedal, detects the pulse signal by utilizing the positive and negative rotation relation between the signal amplification circuit board and the device 8 (Hall sensor 2) and the magnetic pole ring 13 and the bracket which are connected with the middle shaft 1 in a shaft linkage way, and processes the pulse signal into the following components by a chip program: the output of the motor of the power-assisted electric bicycle is controlled by the logical relation of outputting a common-frequency pulse signal when the pedal is positively pedaled/outputting a high level when the pedal is reversely pedaled or stopped, namely, the motor outputs driving power according to the same ratio of the pedal torque when the pedal is positively pedaled (pulsed), and the driving power of the motor is immediately cut off when the pedal is reversely pedaled or stopped (high level).

Initializing a clock, an ADC and a bus after electrification, firstly collecting a voltage signal output by a pressure sensor after initialization is finished, carrying out software filtering after 10 times of collection, and converting a voltage value into a pressure value after normalization and other processing. And then reading the digital signal of the temperature sensor through single bus communication, acquiring the current temperature value, adjusting the pressure value according to the influence factor of the environmental temperature on the pressure sensor, and correcting the temperature drift. And finally, judging the steering of the center shaft through two paths of Hall sensors, outputting a pressure value if the center shaft rotates forwards, and not outputting and re-collecting if the center shaft rotates backwards or does not rotate.

The invention relates to a middle shaft torque sensor which is used as a key part of a middle shaft of an auxiliary power-assisted electric bicycle, wherein manual pedal force is used for driving an output body to output pedal driving force to drive the bicycle to move forwards through a middle shaft linkage force measuring body; the connecting part of the force measuring body and the output body adopts a key technology design inclined plane connection, so that a component force F parallel to the axis to the left side can be sensed on the force measuring body when a human pedal force F rides; the component force F acts on the rotating space ring and the pressing body, finally the component force F is applied to the pressure sensor, and voltage signal output of the component force F in direct proportion to the pedal force F is detected; the pressure sensor is fixed on the bearing body which is axially positioned, so that the pressure sensor does not displace towards the left side when the component force f is applied to the pressure sensor, and the accuracy, repeatability, consistency and origin resetting of measured data are ensured; the structure of the center shaft sensor is simplified, the signal acquisition is more real-time and accurate, the problems of complex technical application, high cost and difficulty in assembly and debugging of the existing center shaft torque sensor can be solved to a great extent, the service life of the sensing unit is prolonged, and the industrial popularization is easier.

In addition, the above-mentioned serial numbers of the embodiments of the present application are merely for description, and do not represent the merits of the embodiments. In the above embodiments of the present application, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.